key: cord- -xwfptmmv authors: liao, qiuyan; cowling, benjamin; lam, wing tak; ng, man wai; fielding, richard title: situational awareness and health protective responses to pandemic influenza a (h n ) in hong kong: a cross-sectional study date: - - journal: plos one doi: . /journal.pone. sha: doc_id: cord_uid: xwfptmmv background: whether information sources influence health protective behaviours during influenza pandemics or other emerging infectious disease epidemics is uncertain. methodology: data from cross-sectional telephone interviews of , hong kong adults in june, were tested against theory and data-derived hypothesized associations between trust in (formal/informal) information, understanding, self-efficacy, perceived susceptibility and worry, and hand hygiene and social distancing using structural equation modelling with multigroup comparisons. principal findings: trust in formal (government/media) information about influenza was associated with greater reported understanding of a/h n cause (β = . ) and a/h n prevention self-efficacy (β = . ), which in turn were associated with more hand hygiene (β = . and β = . , respectively). trust in informal (interpersonal) information was negatively associated with perceived personal a/h n susceptibility (β = − . ), which was negatively associated with perceived self-efficacy (β = − . ) but positively associated with influenza worry (β = . ). trust in informal information was positively associated with influenza worry (β = . ) which was in turn associated with greater social distancing (β = . ). multigroup comparisons showed gender differences regarding paths from trust in formal information to understanding of a/h n cause, trust in informal information to understanding of a/h n cause, and understanding of a/h n cause to perceived self-efficacy. conclusions/significance: trust in government/media information was more strongly associated with greater self-efficacy and handwashing, whereas trust in informal information was strongly associated with perceived health threat and avoidance behaviour. risk communication should consider the effect of gender differences. pandemic influenza a/h n has a clinical profile similar to seasonal influenza, despite initially appearing more severe [ ] . respiratory infectious diseases (rids) such as influenza are a major public health issue best dealt with by prevention, ideally vaccination. however, in the first six-months or so of a newlyemergent rid epidemic/pandemic vaccines are generally unavailable and non-pharmacological interventions can play a major role in minimizing rid spread [ ] [ ] [ ] . government health education messages are a major source of information for promoting self-protective practices against rids. these preventive messages generally emphasize improved hygiene, face-mask use by infected persons, and social distancing measures, including avoiding crowds during epidemics [ ] [ ] [ ] . predictors of population uptake of health protective behaviours in rid epidemics have begun to be studied [ ] [ ] [ ] [ ] [ ] [ ] , yet related theory remains nascent and this is problematic: to effectively predict behaviour during future epidemics robust theory is critical. effective models that enable comprehensive prediction of health protective behaviours remain limited mainly to two overlapping theoretical paradigms: the theories of reasoned action/planned behaviour (tpb) [ ] [ ] [ ] and bandura's concept of self-efficacy [ ] [ ] [ ] (the belief that one can successfully execute some behaviour), particularly regarding the core tpb concept of perceived behavioural control, which controversially is claimed by some to be largely synonymous with self-efficacy [ ] [ ] [ ] and by others to be indistinguishable from intent [ ] (the intention to execute a particular behaviour), the key predictive element of tpb [ ] . when used to account for health-related behaviours tpbbased models typically account for , % of variance in outcomes [ ] , while self-efficacy accounts for , % of variance in outcomes [ , ] . however, neither tpb nor self-efficacy allow for the social and affective influences that might be expected logically to be important in rid [ , ] . we report on a theoretical model that incorporated elements of influenza causal knowledge, perceived self-efficacy and also social and affective influences ( figure ) because these latter variables have been less frequently studied in combination, but have theoretical and logical support for their potential importance in the context of rids. we tested this model against data collected in the early phase of the influenza a/h n pandemic (table s ) to examine how levels of trust in formal and informal sources of risk/prevention information associated with hand washing and social distancing. ethics approval was obtained from the institutional review board of the university of hong kong/hospital authority hong kong west cluster. for this telephone interview, written informed consent was waived by the irb but verbal consent was required from all the respondents and agreement to participate in the interview was taken as further consent. before the interview began, a brief introduction about the study aims and interview contents was given and then respondents were asked whether the interview could start. if approval was received this was recorded and the interview performed. if not, respondents were thanked and the call was terminated. more than % of hong kong households have landline telephones and all local calls are free. random-digit dialled telephone numbers and within-household random-sampling grids (kish grids) are a cost-effective way to survey highly representative random population samples. kish grids are matrices containing random numbers for different sized households that facilitate random selection of individuals within households and help minimize sampling bias. the number of eligible household residents, ''n'', is determined by asking the person of first contact in the household. the kish grid provides a randomly generated number ''k'' between and ''n'' which is used by the interviewer. ordering by age and starting from the oldest eligible member in the household, the k'th member is then invited to participate in the survey. different grid values are used for each household. as part of a series of surveys to monitor a/h n epidemic activity, a commercial polling organization administered the questionnaire using this telephone-survey methodology, targeting , - , participants on each occasion, a sample size calculated to give an estimate of a/h n health protective behaviours with a precision of %. the survey with the largest sample was selected for this analysis. sampling was performed during the evening to minimize exclusion of young working adults. data on attitudes, knowledge, situational awareness, risk perception and preventive behaviours (table s ) were collected by household telephone interviews, based on random digit dialling. one cantonese-speaking adult (age$ ) who lives . nights per week in each household was selected using a kish grid. all interviews were conducted between : pm- : pm from rd - th june, , two weeks after the first community transmission had been identified in hong kong. existing theoretical frameworks of behaviour change have been adapted to predict health-related behaviour-change for chronic, non-communicable diseases [ , ] , but we lack a comprehensive evidence-based model of protective behaviour against rid threat [ ] . a recent review of papers on rid prevention behaviours concluded that lacked a theoretical basis [ ] . existing applications of health behaviour change models in communicable disease are almost exclusively limited to hiv/aids research [ , ] and to a lesser extent hepatitis b and c, which share the same transmission pathways as hiv. there are good reasons why sexually-transmitted diseases embody a different set of influences than do rids. for example people are highly motivated to seek sexual contact (or injection drug use) and have a high degree of potential control (e.g. condom use) over the nature of these encounters, even though they may be situationally constrained from executing that control, and are infected only by direct exchange of bodily fluids. in contrast, one can acquire an rid transmitted by air droplets, hand contact or fomites for up to hours after the person who is the source departs [ ] , or immediately by being sneezed on. infection is much more casual. clearly, the controllability of rids requires different behavioural imperatives to those in stds and hence different psychological influences should be considered. attempts by the tpb to accommodate social influences had relied on incorporating social norms [ ] , the behavioural expectations within a group. however, norms, and hence theoretical models reliant on norms to account for social processes, cannot accommodate the fact that communicable respiratory diseases make other humans ambiguous sources of threat: one can usually control sexual encounters but not who shares public transport. in this respect social factors in communicable respiratory disease differ significantly from those in non-communicable diseases and warrant greater consideration than existing hbc models allow. outbreaks of new infectious diseases constitute situations that are uncertain, dynamic, and embody highly personal threat, requiring rapid decisions on appropriate action [ ] . under such circumstances timely and relevant information on the best preventive actions become critical to such decision-making. hence, health protective behaviour during the early stages of a novel epidemic would be more likely to resemble situational reactions using established or known default actions such as avoiding crowds (social distancing), rather than intention-based planning before any behavioural change, such as deciding to consult a doctor to administer a vaccination. later in the epidemic as threat familiarity increases, different factors such as planned behaviour may become important. reporting delays, uncertainty and other biases affect publicly available information on the characteristics of newly-emergent communicable diseases, such as a/h n lay knowledge of infection-related risks can be limited. the resulting uncertainty about disease severity and transmissibility at the epidemic onset extends to the utility and timing of adopting preventive measures. information cues to individuals about initiating protective action must therefore be synthesized from various sources. perceived information reliability or trustworthiness influences decisions to utilize any given information source [ ] to inform awareness of the situation. more trustworthy sources are therefore likely to be more influential. epidemic situational awareness is likely derived from formally-announced public information like news items, government press releases and health education messages, and also from informal, social sources [ , ] ; observation of other peoples' behaviour and communications from family, peers and neighbours. noting how others behave informs action decisions in the observer [ ] . if those around you are wearing masks, this indicates others might have knowledge you do not possess, and that the threat level might be locally high and imminent, suggesting prudent precautionary or rid preventive behaviour. observers are also subject to social conformity influences that can help adoption of group patterns of behaviour. maintaining situational awareness, involving elements of perception, comprehension and prediction [ ] , during epidemics probably relies on these two types of information. however, when uncertainty is high and widespread, or when there is low confidence in social and other information sources then individuals' hpbs might be expected to be more independent of formal and informal information sources. perceived risk is influenced by several stimulus characteristics, including unfamiliarity, invisibility, dreadfulness and inequity [ ] , and by recipient characteristics, including demographics and trust in information source and content [ ] . perceived risk is an important determinant of protective behavioural responses [ , , , ] , but is subject to optimistic bias, where for example people distort their risk of contracting influenza downwards relative to others [ , ] . nonetheless, susceptibility to risk remains an important measure in understanding variation in behavioural responses to threat and reflects the key element of perceived risk in an epidemic/pandemic situation. worry is a cognitive process linked to anxiety [ , ] and reflects negative affectivity, interacting with perception of susceptibility to risk [ , ] and may also influence rid protective responses such as social distancing [ ] . because data were collected using telephone interviews we had to adapt measures to suit a brief format in order to avoid people hanging up mid-way or providing invalid answers to hurry the interview, a problem encountered with this data collection method. we therefore used parsimonious measure to minimize assessment fatigue and low response rates which threaten representativeness. trust in government/media (formal) information: we asked about respondents' agreement with three statements (table s ). responses were made on categorical five-point scales ranging from ''strongly disagree'' to ''strongly agree''. scalability of these three items was assessed using cronbach's alpha, which at . indicated that the internal consistency between items was low, but acceptable. however, to minimize potential measurement error arising from the low internal consistency, this construct was treated as a latent variable in the subsequent analysis [ ] . a latent variable is a concept opposed to an observed variable. a latent variable can not be measured directly but is inferred from one or more variables that are directly measured (observed variable) while an observed variable can be directly measured with a specific question or item or observed by the researchers. for example, an ''attitude'' is a concept that is difficult to measure directly with single items but can be inferred from various questions asking about different aspects of that attitude. then within the analysis ''attitude'' is treated as the latent variable while the questions used to infer it are the observed variables. trust in interpersonal (informal) information: respondents' agreement with two statements (table s ). responses were made on categorical five-point scales ranging from ''strongly disagree'' to ''strongly agree''. scalability of these two items was assessed using cronbach's alpha, which at . indicated that scalabilty was unsuitably low for two items. this suggests that these two items measure different aspects of social information. again to minimize potential measurement error this construct was treated as a latent variable in the subsequent analysis. understanding cause of a/h n (''i understand how swine flu is caused'') and self-efficacy (confidence in one's ability to act in a way that achieves desired future outcomes) for a/h n prevention (''i am confident that i can protect myself against swine flu''): each was assessed using responses on -point scales of agreement with these two single item statements (table s ) . perceived personal susceptibility: two items, one assessing absolute susceptibility (perceived absolute probability of developing a/h n ) and another assessing relative susceptibility (perceived probability of developing a/h n relative to peers) formed a latent variable for perceived personal susceptibility (table s ). the cronbach alpha of these two items was . . worry about contracting h n . respondents were asked to indicate their level of worry over the past one week about contracting influenza a/h n . responses were -point scales of worry ranged from ''never thought about it'' to ''extremely worried'' (table s ). hand hygiene. respondents were asked to indicate frequencies of use of four hand hygiene practices over the three days prior to interview: hand washing after sneezing, coughing and touching nose; hand washing after returning home, use of liquid soap for hand washing, and hand washing after touching common objects. responses were on a -point scale of frequency: ''never'', ''sometimes'', ''usually'' and ''always''. cronbach's a was . (table s ). social distancing behaviours: a. social avoidance. respondents were asked to indicate if they had adopted any of four avoidance behaviours due to influenza a/h n in the past days: avoiding eating out, avoiding using public transport, avoiding going to crowded places, and rescheduling travel plans responses were coded as ''yes'' and ''no''. cronbach's a was . (table s ). we first compared the demographic structure of the sample against that of the general population derived from the hong kong government general household survey to identify any sample differences. our model proposes that trust in formal (government and media sources) and informal (from other people) information affects rid epidemic health protective behaviours, the former by informing about generic risk and response characteristics for dealing with a potential threat (causes and protective responses), the latter about threat imminence, severity and response effectiveness (seeing how others behave). we refer to the product of these combined processes as situational awareness, and propose that rather than driving behaviour directly information acts through altering the cognitive/affective domain of situational awareness. thus the model is predicated on several premises: that understanding of the disease and perceived personal susceptibility influence self-efficacy [ , , ] ; that the effect of perceived susceptibility to influenza on hpbs acts through increasing worry about the disease [ , , , , ] ; and that more worry from perceived susceptibility prompts hpbs [ , , ] . these cognitive/affective processes are represented in the hypothesized model ( figure ). structural equation modeling (sem) is a method for simulating and testing multiple and interrelated causal relationships simultaneously in statistical data, making it suitable for theory development and testing [ ] . sem was applied to test the hypothesized model. sem is usually performed when a model contains latent variables assessed with specified measurement models. despite including estimations of a series of multiple regression equations, sem differs from regression analysis in several ways, which make it advantageous for this kind of analysis. first, sem is usually theoretically based because it is performed after researchers specify the hypothesized model. second, it can be used to refine the hypothesized model by estimating the measurement model and structural model simultaneously. finally sem analysis can accommodate measurement errors of the constructs in the model [ ] . in our hypothesized model, trust in formal information, trust in informal information, perceived personal susceptibility, hand washing and social distancing behaviours were entered as latent (inferred) variables while other constructs were entered as observable (directly measured) variables because they were assessed with only one item. two different health protective behaviors, hand washing and social distancing, were entered as the hpb outcomes because we hypothesized that different influences may act on each of these. we assumed that the ''disturbances'' of the two health behavior outcomes were correlated. disturbance represents the unexplained variances of the latent variables predicted by the specified independent variables [ ] . in making this assumption, we assumed that unexplained variance in the outcome variables could be correlated and the variables in question jointly influenced by other unknown factors, and so allowed for such constraints within the model by using more conservative criteria. previous studies have shown that hand hygiene and social distancing behaviours during a pandemic could be influenced by some common causes which were not fully explored in our study such as current health, past experience of disease and cues to action [ ] . in particular, in our study, the two kinds of health protective behaviours occurred in the same situation of the influenza pandemic, and so it is sensible and reasonable to assume that they could be influenced by some common causes which were not fully explored in our studies. adequacy of the measurement models was tested before testing the full structural model. to test the full structural model, all constructs ( figure ) were entered into the model and all factor loading, specified paths, covariance, measurement errors and disturbances were estimated simultaneously. since the model contained categorical variables, weighted least square with mean-and variance-adjusted estimation (wlsmv) was used to estimate the standardized parameter (b) for each path [ ] . with this kind of estimation, chi-square difference testing is inappropriate. we therefore used the comparative fit index (cfi), tucker-lewis index (tli) and root mean squared error of association (rmsea) to evaluate the model fit to the data. a cfi. . , tli. . and rmsea, . indicate a good fit of data to the model [ ] . the analysis was conducted in mplus . for windows [ ] . the proportion of missing values ranged from . % for ''in the past one week, have you ever worried about catching influenza a/h n '' to . % ''did you wash hands after sneezing, coughing or touching nose in the past days''. missing data were handled with multiple imputation to generate datasets which were summarized into one for subsequent analysis. multiple imputation was performed in ameliaview [ ] . responses are likely to differ by sociodemographic factors [ ] . we therefore stratified the sample by gender and by age (, years old vs. . years old). education is also likely to have a significant effect but there are difficulties in education stratification in hong kong. the age cut-off of years was adopted to account for the introduction in hong kong of -year compulsory education in and -year compulsory education in [ ] . this means that people aged or above are much less likely to have a tertiary (college/university) level education and less secondary (high school) education than people aged , years old [ ] . moreover, in traditional families in china, a son (who lived with his parents after marriage) was usually more educationally-favoured over daughters (who moved to their in-laws' home on marriage) to ensure support for the parents in their old age, so males usually obtained more education than females [ ] . these distinctions were somewhat evidenced by our data which showed that % of the respondents aged , compared to % of the respondents aged or above (x = . , p, . ), and % of male compared to % of female respondents, obtained at least secondary education (x = . , p, . ). since the numbers of tertiary educated respondents and primary (elementary) educated respondents were too small to produce stable models, we limited stratification to gender and age only and acknowledge that this also incorporates indefinable education and income effects. consequently, we used a multi-group sem to assess the invariance of the model (figure ) across gender and age group (respondents aged - and aged or above). we tried to test the model by stratifying the sample into four subgroups (female aged - , female aged or above, male aged - and male aged or above). however, the sample size for males aged - was relative small (table s ) . moreover, all the model variables were treated as categorical variables and we used the wlsmv method to estimate the model. this method requires that each subsample covers all the categories of each variable. in the case of one category, younger males, not all variable values were present. to meet the assumptions for analysis we would need to recode all variables, intrinsically altering the model. in order to avoid this, we relinquished a combined four-group comparison and instead compared the model across gender and the two age groups separately. to perform multigroup comparison we first ran a model with all parameters unconstrained. we then identified factor loadings that were not significantly different (p$ . ) and set these as equal, while loadings that were significantly different were allowed to vary, and finally paths that did not differ significantly were constrained to be equal while those that differed significantly were allowed to vary and estimated separately by groups. the ''difftest'' option in mplus . was used to obtain a correct chi-square difference test for the wlsmv estimators and was used to estimate the differences between the least constrained model (with all the paths freely estimated) and the most constrained model (with all the paths constrained to be equal) as well as the partially constrained model (with some of the paths freely estimated and others constrained to be equal) [ ] . a p-value. . for the ''difftest'' indicate a nonsignificant difference between the models. finally, to help interpret these multigroup sem comparisons, we performed a post-hoc examination of the model variable means for different gender and age groups and tested differences using the mann-whitney test, which tests differences between two groups on ordinal scales of measurements. a total of , / , ( . % response rate) hong kong adults successfully completed the interview. the characteristics of the sample were compared against the hong kong by-census population data [ ] , showing respondents to be better educated and more likely to have been born in hong kong compared to the general population (table ) but otherwise representative. both formal and informal information trust were correlated with all situational awareness variables except worry about contracting a/h n (''worry''), while formal information trust was also independent of perceived personal susceptibility (''susceptibility''). in turn, understanding of h n cause (''understanding'') and perceived self-efficacy (''self-efficacy'') were significantly associated with hand washing while worry and susceptibility were significantly associated with social distancing (table s ). the sem model fitted well to the data with cfi = . , tli = . and rmsea = . . standardized coefficients indicated two primary features in the model; the first one linking formal information and hand hygiene and a second linking informal information and social distancing ( figure ). paths were seen via formal information trust and self-efficacy (b = . ) and self-efficacy and hand hygiene (b = . ), and via formal information trust and understanding (b = . ), and understanding and hand hygiene (b = . ) while understanding and selfefficacy were independent. these associations formed the first feature. marginal associations between worry and hand hygiene and between self-efficacy and social distancing were seen, but the small standardized coefficients of b = . suggest that these paths are minor. susceptibility and worry were associated, but otherwise were functionally independent, both upstream from formal information trust, and downstream from hand hygiene. the second feature of the model is reflected in a different set of paths associating informal information trust with social distancing. trust in informal information sources was inversely associated with susceptibility (b = . ), which was associated positively with worry (b = . ), and inversely with self-efficacy (b = . ). however, more confidence in informal information sources was associated with more worry (b = . ) and finally, only worry was associated with social distancing (b = . ). trust in informal information was independent of understanding and self-efficacy. the only remaining notable feature of the model was a strong inverse association (b = . ) between susceptibility and selfefficacy. this suggests some interaction between these two variables that could strongly influence both sets of paths mentioned so far. overall, the model explained . % of the variance in hand hygiene and . % of the variance in social distancing behaviors. across gender, both the least constrained model and the most constrained models fit the data well with cfi. . , tli$ . , rmsea = . . the most constrained model did not differ significantly from the least constrained model (x for ''difft-est'' = . , d f = , p = . ). however, three sets of associations differed significantly between females and males: those between formal information trust and understanding, from informal information trust to understanding, and from understanding to self-efficacy. these paths were set free and estimated separately in female and male. the model with these paths freely estimated fit well to the data with cfi = . , tli = . and rmsea = . , and did not differ significantly from the least constrained model (x for ''difftest'' = . , d f = , p = . ). figure presents the results of multigroup comparison of the model applied to males and females with the three path parameters unconstrained. for a given path, if the path coefficients did not differ significantly between males and females, only the path coefficient for males is presented; if the path coefficients differed significantly between males and females, the path coefficients for both genders are presented with the coefficients for males presented on the left of the slashes and for females presented on the right of the slashes. by comparison, the model shows that for both genders while the association between formal information trust and understanding was positive this association was stronger amongst females (b = . ) than males (b = . ); the association between informal information trust and understanding was weakly positive in males (b = . ) but weakly negative in females (b = . ), and; the association between understanding and self-efficacy was positive (b = . ) in males but non-significant in females (b = . ). across the two age groups, both the least constrained model and the most constrained model fit well to the data with cfi. . , tli$ . , rmsea# . . the most constrained model did not differ significantly from the least constrained model (x for ''difftest'' = . , d f = , p = . ). no path was found to be significantly different between the two age groups. means and standard deviations for all model variables by gender and age group showed differences (table s ). all the constructs did not differ by gender except for hand hygiene and social distancing with female being more likely to wash their hands and adopt social distancing behaviours. trust in formal and informal information sources, self-efficacy, and hand hygiene significantly differed by age groups, with respondents of older age group being more likely to trust the information from both sources, perceive higher self-efficacy and wash their hands. we tested a hypothesized model of associations between trust in (formal/informal) information, situational awareness variables (causal understanding, self-efficacy, susceptibility and worry) and different types of health protective behaviours (hand hygiene and social distancing) for influenza protection. the model suggested that two different sets of influences relate trust in information to hand hygiene, and to social distancing respectively. the strongest associations observed were between susceptibility and self-efficacy neither age nor gender contributed significant variation to the association between trust in formal information and self-efficacy, and self-efficacy and hand hygiene. these findings are consistent with other studies showing self-efficacy is enhanced by procedural information [ , , , ] and that attitudinally and actionoriented interventions are more successful in changing behaviour for communicable disease protection, such as in the case of hiv [ ] . similarly, exposure to relevant media stories during the a/h n influenza pandemic was associated with higher efficacy beliefs regarding hygiene, which in turn was associated with greater frequency of reported tissue access and sanitising gel purchase among british people [ ] . however, there is evidence that coping style interacts with the ability of procedural information to enhance self-efficacy and under circumstances of high threat, such as during sars-type epidemics where mortality is high, procedural information might be counter productive for some segments of the community who use an information avoidance (''blunting'') coping style [ ] . self-efficacy was only weakly associated with social distancing. people are limited in their ability to avoid crowds in hong kong, one of the most densely populated cities on earth, despite the hong kong government recommending this in order to limit the pandemic [ ] . however, the relatively mild impact of a/h n meant that people saw no reason to jeopardize their economic well-being and curtail other social activities, given such a low perceived threat [ , ] . hand washing was probably seen as sufficient protection. the association between trust in formal information and understanding of influenza cause differed by gender but not age, with females showing a stronger association. men tend to have poorer health knowledge than women [ ] . we found that females were more likely to wash their hands than were males. older respondents reported significantly greater trust in formal information, marginally-significantly better understanding of influenza cause and were more likely to wash their hands. this is consistent with other studies reflecting that preventive practice is enabled by knowledge of causes [ , ] . however, increasing knowledge is not itself sufficient to always ensure preventive behaviour [ ] . in this context, understanding has an independent contribution to hand washing practice only. trust in informal information seems to be associated with less perceived susceptibility to health threat. this may reflect rational processes or cognitive bias. trusting social cues involves comparison and conformity influences, and can enhance optimistic bias (the tendency to view oneself less likely to experience negative events but more likely to experience positive events) in personal risk estimates [ ] , thereby reducing perceived susceptibility. conversely, others' behavioural cues about health threat proximity can arouse motivating worry and anxiety producing protective action [ , ] . we found trust in informal information was independent of both understanding of influenza cause and self-efficacy. however, when stratified by gender, the trust in informal information-understanding association was positive among males but negative among females. education is probably an important influence in understanding and may have a bearing on these patterns which await clarification. susceptibility was strongly associated with both self-efficacy (negatively) and worry (positively). neither worry nor susceptibility varied significantly by gender or age group. this is plausible and theoretically consistent [ , , , ] . worry was strongly associated with social distancing, again consistent with british data [ ] . although worry was also significantly associated with hand hygiene, the association was weak. elsewhere, using a generic measure of personal hygiene practices we have found a stronger association between disease worry and hygiene, suggesting a moderate effect of level of disease worry [ ] . the model tested explained only a modest proportion of the variance in adoption of hbps, suggesting that there are significant theoretical gaps that remain to be filled. these await further research. social distancing is unassociated with formal hpb messages, suggesting potential susceptibility to a ''herd-like'' response in this chinese community, particularly if confidence in formal (government or doctors) information is low. voerten and colleagues describe such a pattern of response in the early stages of sars [ ] . these models support the hypothesis that social distancing is more likely to occur when perceived health threat is high [ ] . logically, when others seem to be behaving in a way that is informed and probably consistent then their actions provide clear information. if mixed social messages occur signalling uncertainty then the utility of social information will fall. this is likely to be associated with increase perceived susceptibility, and possibly greater worry and distancing behaviour. this pattern of responses would be most likely early in a novel rid epidemic where disease characteristics and behaviour are often uncertain. high threat uncertainty then drives social avoidance of potentially high-risk others. high levels of worry are associated with greater social distancing. around % of / , (response rate %) british respondents agreed that social avoidance would minimize risk of a/h n infection, and respondents reporting more anxiety were more likely to engage in preventive actions; severity and likelihood of infection were the most important determinants of preventive action [ ] . further research on social influences on hpb during epidemic and pandemic rids is warranted. providing more knowledge about disease causes can improve hand hygiene but is unlikely to influence social avoidance, which appears less amenable to formal health messages. however, as formal messages achieve acceptance across the population, and uptake of hpbs increases, then under circumstances where a critical mass of the population are practicing precautions trust in informal information should increase, reducing susceptibility and worry and leading to declines in social avoidance. because others are likely adopting hpbs this makes them less of a contagion risk. conversely maintaining a high level of hand washing practices may require sustained public education activities. finally, different segments of the population probably communicate different types of information with their peers. self-efficacy in preventing a/h n influences hand hygiene but has little influence on social distancing. formal health education messages that focus on enhancing the public's sense of their ability to protect themselves by adopting hygiene practices would seem to be the most effective to improve hand hygiene, but where the practice is already established, high levels of trust in these messages are not likely to significantly increase hand hygiene. this study is limited in being cross-sectional and relying on hypothesized modeling to infer causality. this is potentially errorprone and can only be confirmed by specific longitudinal tests of the hypotheses proposed above. there are potential limitations related to measurement imposed by the need to be parsimonious in questioning due to use of telephone interviews. where this is not done refusal rates would have been unacceptably high [ ] raising serious questions about representativeness. as a consequence, construct validity for some latent variables was weaker than expected, for example, only two items were scaled to measured trust in informal information giving a low internal consistency. we re-ran the sem treating the two trust items as separate which gave almost identical associations with different situation awareness variables, so we entered their combined score as a latent variable in the final model. only one item measured self-efficacy. this is generally not considered adequate but does have precedent indicating it is valid for predicting behavioral change [ ] . finally, this random sample, closely representative of the population of hong kong and collected early in the epidemic phase, nonetheless was slightly older and less-well educated than the general population. this was likely due to unavoidable sampling bias from surveying in the early evening to pm. many young adults do not return home from work until after this time and were thereby not sampled. the results may in part reflect this bias. otherwise the response rate was high at % and excellent compared to similar studies [ ] . some of these above limitations may also have contributed to the low explained variance of the model. many factors influence rid protective behaviour. this study has examined a very limited number of these. confidence in formal information such as health education messages is associated with greater compliance to recommended preventive measures for influenza a/h n [ ] . however, the mechanisms for this were unclear. we have shown that this probably involves different mechanisms for hand washing and social distancing, and suggest how these might function. formal messages may not reduce social distancing behaviours until such time that preventive behaviours are widely adopted in the community. social distancing seems more likely to occur when there is high influenza-related worry and uncertainty, such as in the initial stages when epidemic circumstances are unknown, or if an epidemic is severe and appears poorly controlled, as during early sars. this would seem to be largely worry/affect-driven. if so, then social distancing is likely to occur irrespective of government messages as population anxiety about an epidemic increases. susceptibility may also increase and this may inhibit self-efficacy regarding hand washing. finally, high levels of community uncertainty or rumour are likely to increase distancing by exacerbating perceived susceptibility and worry. a simple version of our findings can be found it the supporting file (text s ). table s found at: doi: . /journal.pone. .s ( . mb doc) text s this is a simple version of our study findings for nonspecialists. found at: doi: . /journal.pone. .s ( . mb doc) pneumonia and respiratory failure from swineorigin influenza a (h n ) in mexico efficacy of soap and water and alcohol-based hand-rub preparations against live h n influenza virus on the hands of human volunteers facemasks and hand hygiene to prevent influenza transmission in households: a cluster randomized trial school closure and mitigation of pandemic (h n ) , hong kong cdc says ''take '' actions to fight the flu pandemic influenza prevention and mitigation in low resource communities prevention of avian influenza the impact of community psychological responses on outbreak control for severe acute respiratory syndrome in hong kong an outbreak of the severe acute respiratory syndrome: predictors of health behaviors and effect of community prevention measures in hong kong, china psychosocial factors influencing the practice of preventive behaviors against the severe acute respiratory syndrome among older chinese in hong kong risk perceptions related to sars and avian influenza: theoretical foundations of current empirical research public perceptions, anxiety, and behaviour change in relation to the swine flu outbreak: cross sectional telephone survey demographic and attitudinal determinants of protective behaviours during a pandemic: a review attitudes towards objects as predictors of single and multiple behavioral criteria the theory of reasoned action: a meta-analysis of past research with recommendations for modifications and future research the theory of planned behavior: a review of its applications to health-related behaviors social foundataions of thought and action: a social cognitive theory self-efficacy: the exercise of control health promotion from the perspective of social cognitive theory perceived difficulty in the theory of planned behaviour: perceived behavioural control or affective attitude? perceived control moderated the self-efficacy-enhancing effects of a chronic illness self-management intervention self-efficacy, controllability and intention in the theory of planned behavior: measurement redundancy or causal independence? self-efficacy, problem solving, and social-environmental support are associated with diabetes self-management behaviors prevention of sexually transmitted hiv infection: a meta-analytic review of the behavioral outcome literature sources of information and health beliefs related to sars and avian influenza among chinese communities in the united kingdom and the netherlands, compared to the general population in these countries cognitive appraisal, negative affectivity and psychological well-being a review of health behaviour theories: how useful are these for developing interventions to promote long-term medication adherence for tb and hiv/aids? survival of influenza viruses on environmental surfaces a framework for capturing the interactions between laypersons' understanding of disease, information gathering behaviors, and actions taken during an epidemic communication of risk: choice, consent, and trust toward a theory of situation awareness in dynamic systems perception of risk trust, emotion, sex, politics, and science: surveying the riskassessment battlefield factors in vaccination intention against the pandemic influenza a/h n avian influenza risk perception and live poultry purchase in risk perception and their relation to risk behavior what causes h n avian influenza? lay perceptions of h n etiology in south east and east asia distinct and overlapping features of rumination and worry: the relationship of cognitive production to negative affective states risk perception and affect principles and practice of structural equation modeling emotions and preventive health behavior: worry, regret, and influenza vaccination risk perceptions: assessment and relationship to influenza vaccination mplus user's analyzing incomplete political science data: an alternative algorithm for multiple imputation education encyclopedia -stateuniversity.com ( ) hong kong -history & background, constitutional & legal foundation, educational systemoverview, preprimary & primary education, secondary education main tables of the population census. hong kong: government of the hong kong sar effects of preparatory videotapes on self-efficacy beliefs and recovery from coronary bypass surgery an interactive course to enhance self-efficacy of family practitioners to treat obesity the impact of communications about swine flu (influenza a h n v) on public responses to the outbreak: results from national telephone surveys in the uk coping with gastrointestinal endoscopy: self-efficacy enhancement and coping style human swine influenza on sars type economic effects during infectious disease outbreaks determinants of health knowledge: an investigation of age, gender, abilities, personality, and interests knowledge, attitudes, and preventive practices about colorectal cancer among adults in an area of southern italy knowledge, attitude and practice about sexually transmitted diseases among university students in kampala do moderators of the optimistic bias affect personal or target risk estimates? a review of the literature social-cognitive factors and personal hygiene practices to protect against influenzas: a structural equation model comparing avian influenza a/h n and pandemic a/h n in hong kong we thank the hku public opinion programme for assistance in administering the telephone survey. we thank dennis ip, angela shen and joseph wu for helpful discussions. we also thank lincoln lau and vicky fang for technical assistance. analyzed the data: ql. wrote the paper: ql. planned the study: rf, bc. key: cord- -zyaj nh authors: wong, samuel ys; wong, eliza ly; chor, josette; kung, kenny; chan, paul ks; wong, carmen; griffiths, sian m title: willingness to accept h n pandemic influenza vaccine: a cross-sectional study of hong kong community nurses date: - - journal: bmc infect dis doi: . / - - - sha: doc_id: cord_uid: zyaj nh background: the pandemic of influenza a (h n ) infection has alerted many governments to make preparedness plan to control the spread of influenza a (h n ) infection. vaccination for influenza is one of the most important primary preventative measures to reduce the disease burden. our study aims to assess the willingness of nurses who work for the community nursing service (cns) in hong kong on their acceptance of influenza a (h n ) influenza vaccination. methods: questionnaires were posted from june , to june , to community nurses with % response rate. results of the respondents on their willingness to accept influenza a (h n ) vaccine were analyzed. results: twenty-seven percent of respondents were willing to accept influenza vaccination if vaccines were available. having been vaccinated for seasonable influenza in the previous months were significantly independently associated with their willingness to accept influenza a (h n ) vaccination (or = . ; % ci: . - . ). conclusions: similar to previous findings conducted in hospital healthcare workers and nurses, we confirmed that the willingness of community nurses to accept influenza a (h n ) vaccination is low. future studies that evaluate interventions to address nurses' specific concerns or interventions that aim to raise the awareness among nurses on the importance of influenza a (h n ) vaccination to protect vulnerable patient populations is needed. the pandemic of influenza a (h n ) infection has alerted many governments to make preparedness plan to control the spread of influenza a (h n ) infection. with evidence on the effectiveness of vaccination in the control and prevention of seasonal influenza [ , ] , vaccination for pandemic influenza is one of the most important primary preventative measures to reduce the disease burden associated with influenza a (h n ) infection [ ] . several high risk groups have been identified as "the priority group" to receive the influenza a (h n ) vaccination and among these, healthcare workers have been identified "as a first priority" to be vaccinated against influenza a (h n ) by the world health organization [ , ] . although it is considered essential for all healthcare workers to be immunized against influenza a (h n ) to prevent the spread of influenza a (h n ) to patients as the pandemic evolves, previous studies that have examined the acceptability of seasonal influenza vaccination among healthcare workers have generally demonstrated a low acceptance rate of vaccination in this group [ , ] . among all healthcare workers, nurses constitute the largest group with the highest frequency of contacts with patients and staff [ ] . previous findings of the acceptability of seasonal influenza vaccination in nurses showed that their acceptance of vaccination was lowest among all healthcare workers [ , , , ] . acceptability of influenza a (h n ) vaccination in healthcare workers has been shown to be low [ ] [ ] [ ] . a survey conducted in greece found that only % of hospital healthcare were willing to receive influenza a (h n ) vaccination [ ] . of all healthcare workers, nurses were found to have the lowest rate of acceptability of influenza a (h n ) vaccination [ , ] . a study of italian healthcare workers showed % of nurses willing to accept vaccination compared to % of physicians [ ] . in a study conducted of hong kong healthcare workers in hospitals, it was found that only % of nurses were willing to accept influenza a (h n ) vaccination, compared with % of doctors and % of allied professionals [ ] . general practitioners working in the community in france also report a high rate of acceptability of influenza a (h n ) vaccination at % [ ] . it is therefore not surprising that a recent online poll conducted in the uk suggested that nurses may be unwilling to receive pandemic influenza vaccination [ ] . in a cross-sectional survey that was conducted on experienced nurses who were members of the nursing professional organizations in hong kong, the vaccination rate for seasonal influenza vaccination was about % [ ] . in a more recent survey that explored influenza a (h n ) acceptance rate in the same group of nurses [ ] , it was found that only % were willing to accept vaccination for influenza a (h n ) compared to % who plan to receive the seasonal influenza vaccination. however, in the study, there was a low response rate of % of nurses with different clinical settings. there is a lack of studies in hong kong looking at influenza a (h n ) vaccination acceptability particularly in the community setting. nurses who work in the community may be the first group to be in contact with patients who are affected with the influenza a(h n ) infection. a recent study [ ] showed differences in the concerns in using new vaccines during a pandemic than using established vaccine in a non-crisis situation. therefore, we undertook the current study to examine the willingness of frontline registered nurses who work in the community in hong kong to receive vaccination against influenza a (h n ) at the time of a pandemic. all participants in this study were specially trained nurses, who provided nursing care and treatment for patients in their own homes (also known as community nursing service) in hong kong. the responsibility of these community nurses is to provide nursing care and health education to patients through home visits. cns nurses are employed by hospital authority in hong kong and provide continuity of care for patients who have been discharged from hospitals such that patients can recover in their own homes. community nurses were chosen because of their frequent contacts with patients in their homes which is likely to increase their risk for exposure to influenza. we have only included cns nurses who provide medical services in the study. the rest of the cns nurses (around nurses) provide psychiatric services in the community. currently, there are a total of nurses who provide medical related services for the community nursing service (cns) centres that are distributed among the geographical clusters in hong kong (in hong kong, public hospital and primary care services are organized in clusters that covers all of hong kong). in this study, twelve major cns centres were contacted first and all cns nurses were invited to participate in the current study through these major centres. all centres responded to this study and questionnaires were returned with completed questionnaires [ ] . the response rate for this study was % and all questionnaires were received within a week period at a time when there was widespread h n in the community. the survey was sent out from june th to june th , when the who influenza pandemic alert level assigned to h n was phase . phase signifies a widespread human infection, indicating that the virus has caused sustained community level outbreaks in at least one other country in another who region (who pandemic phase description). the pandemic in hong kong started on st may, when a mexican traveller was confirmed with influenza a (h n ). till the end of our data collection, there were confirmed cases and no death were reported. all general managers of the involved community nursing centres were contacted through telephone to obtain approval to send questionnaires to their nursing staff. in total, self administered, anonymous questionnaires were posted to general managers of centres who then passed these questionnaires to the community nurses in their centres. the general managers of centres were then reminded via telephone during the period from nd july and th july one week after the questionnaires were sent out and advised to return the completed questionnaires within the week. once completed, questionnaires were collected and returned by their supervisors, except for one of the (sau mau ping) sub-offices, where nurses mailed back their questionnaires individually. all centres sent their questionnaires back after one telephone reminder. the last pile of completed questionnaires was received on th july, . the questionnaire consisted of six parts with questions and the full questionnaire can be accessed by contacting the authors. the first four parts were based on a conceptual framework developed by patel et al [ ] to guide systematic planning for community primary care service response to pandemic influenza with modifications to make it more relevant for nurses. we added a fifth part on psychological responses to pandemic influenza and a sixth part on demographics of respondents which were based on two studies previously published (one on general practitioners' response to sars and one on general public response to swine flu) [ , ] . in summary, these sections were ) clinical services change as a response to pandemic influenza; ) internal environment changes as a response to pandemic influenza e.g. wearing of mask; ) macro-environmental changes as a response to pandemic influenza e.g. use of guideline etc; ) professional and public health responsibilities with respect to pandemic influenza; ) attitude and psychological responses to pandemic influenza; and ) demographics and year of education of respondents. the willingness to accept influenza a(h n ) vaccination was asked in the professional and public health responsibility sections and the question "will you receive the new influenza a (h n ) vaccine when it is available" was asked with a dichotomous "yes" or "no" response. for those who answered no, they were further asked to give their reasons for refusing to receive the vaccine. only results on willingness of accept influenza a (h n ) vaccination and information related to the analysis on willingness to accept vaccine are reported in this paper. other results from this survey will be presented in a separate report. descriptive results were cross-tabulated. χ test was used to examine characteristics between nurses who were willing to accept influenza a (h n ) vaccination against those who were not willing to accept vaccine. univariate analysis was performed with demographic information (age, post year education and working district), personal protective behaviour (hand washing practice), experience of taking care of sars patients, and influenza vaccination in the previous months as independent variables. dependent variables were the willingness to receive pandemic influenza vaccination. multiple logistic regression analysis was conducted to examine the relationship between pre-defined factors that we think might be associated with the acceptance of the influenza a (h n ) vaccine when constructing the questionnaire and the dependent variable. the level of statistical significance was set at a p-value of ≤ . . among the respondents ( table ) , most of them were females who had worked an average of . years as a community nurse (ranging from months to years) and having been a registered nurse for . years (ranging from year to years). the mean age of respondents was . years and about a third ( %) had had the experience of dealing with sars. one third of them had received vaccination for seasonal influenza in the past months. nurses from each geographical cluster in hong kong participated, with % of respondents working in hong kong island, % working in kowloon and % working in the new territories (hong kong is geographically divided into hong kong island, kowloon peninsula and the new territories). overall, ( %) participants do not want to receive new influenza a (h n ) vaccine when it is available. the reasons for their not intending to receive vaccination when it is available are summarised in table . the characteristics of respondents who were willing to accept influenza a (h n ) vaccination and with those who were not willing to accept influenza a (h n ) influenza vaccination were compared by χ test and were presented table . nurses who were willing to receive influenza a (h n ) vaccine were different from nurses who were not willing to receive influenza a (h n ) vaccine with respect to "being vaccinated against seasonal influenza vaccination in the previous months". there were no statistical significant differences in other characteristics as analyzed by chi-square test. the relationship between demographic and other characteristics of the nursing respondents and their willingness to accept vaccination were analyzed further using forced entry logistic regressions (table ) . having seasonal vaccination in the past months was significantly independently associated with the willingness to accept influenza a (h n ) vaccination (or = . ; % ic: . - . ). washing hands before and between patient contact, however, was negatively independently associated with willingness to accept influenza a (h n ) vaccination (or = . ; % ic: . - . ). to confirm the results, we have also conducted backward logistic regression and the results also indicated that having seasonal vaccination in the past months was significantly associated with the willingness to accept influenza a (h n ) vaccination (or = . , % ci: . - . , p < . ). consistent with findings from previous surveys conducted in hospital healthcare workers and nurses [ , ] , we have shown that the majority of nurses from community nursing services in hong kong were not willing to be vaccinated against h n influenza when the vaccine becomes available. similar to findings from previous studies in healthcare workers [ , , , ] , we showed that the major concerns for vaccination against pandemic influenza was fear of side effects and concern of efficacy of the new vaccine (table ) . moreover, influenza vaccination in the previous months was significantly associated with their willingness to accept the pandemic influenza vaccination. we also showed that in addition to previous vaccination with seasonal influenza, preventive behaviours such as frequent hand washing practice were independently associated with nurses' willingness to accept influenza a (h n ) vaccination. we showed that "have been washing hands between and before patient contact" was negatively associated with willingness to accept vaccination independently although the reason for this is unclear and be a result of our relatively small sample. we can only postulate that the barrier to pandemic influenza vaccination is probably not related to the willingness of nurses to protect themselves against infections or their personal hygiene in general. researchers [ ] have suggested one of the barriers to pandemic influenza vaccination in nurses was misconceptions about the purpose of vaccinations in which nurse might think that the aim of vaccination was for self protection rather than to protect at risk populations in contact with them [ , , ] . specific vaccination policy for health care workers may improve vaccination in this group as nurses have different concerns and priorities when compared to the general public's concerns [ , ] . although some may suggest that more educational programs for healthcare workers may be a solution to the low vaccination uptake [ ] , studies have reported low influenza vaccination rates among healthcare workers even when educational programs were implemented [ ] . other studies including randomized controlled trials also failed to show that better knowledge or educational programmes ( ) other concerns (i.e. pregnancy, poor health status, and the severity of the epidemic of h n ) (< . ) note: the total percentage exceeds % because multiple responses were allowed. were effective in increasing acceptability of vaccination in healthcare workers [ ] . indeed, some suggested that educational campaigns based on the health belief model were unlikely to be enough to change healthcare workers' acceptability of vaccination as evidence showed that perceived seriousness of infection, acknowledgement of increased risk of infection and knowledge of vaccine being safe were unrelated to vaccine uptake in healthcare workers [ ] . others suggested that educational programmes may be counter-productive as many of these healthcare workers do not perceive themselves to be at risk for contracting the infection. recently, ofstead et al [ ] suggested that an ecological model, which included engaging organizations, communities and policy makers to create environments that were more conducive to risk reduction, might be more effective in increasing vaccination rates in healthcare workers. to our knowledge, this is the first study to explore the willingness of nurses who work in the community to be vaccinated for pandemic influenza and our results confirmed that their acceptability of influenza a (h n ) vaccination is low. a strength of our study is our response rate of % which is higher than similar report conducted in hong kong with a response rate of % [ ] . a limitation of our study is that we have only documented nurses' intentions of when a vaccine is available and not the actual uptake of vaccination. furthermore, all data from this study were from self-reports and recall bias, such recalling influenza vaccination in the previous year, might have occurred. a possible contributory factor e.g. recent episode of influenza-like illness which may influence the willingness of vaccination was not enquired. our analysis of results was limited by the relatively small sample size in nurses who are part of the community nursing service in hong kong with no information available on non respondents. however, our results are similar to recent studies conducted in hospital healthcare workers [ ] and members of professional nursing organizations [ ] in hong kong. consistent with previous findings which were conducted in healthcare workers and nurses [ , ] , we confirm that the acceptance rate of pandemic influenza vaccination is low amongst community nurses. since community nurses are at high risk of contracting influenza infection, and play a significant role in caring for community cases, special attention should be paid to this group as successful vaccination strategy has been shown to be beneficial in disease transmission [ ] . future work, including interventional studies evaluating potential interventions based on the ecological model or interventions that aim to increase awareness among nurses on the importance of vaccination in healthcare workers to protect vulnerable populations [ ] is needed. the need to address low influenza vaccination rates in this high-risk group is urgent in the context of pandemic response. vaccines for seasonal and pandemic influenza efficacy and effectiveness of influenza vaccination stockpiling prepandemic influenza vaccines: a new cornerstone of pandemic preparedness plans healthcare workers should get top priority for vaccination against a/h n flu, who says who global influenza preparedness plan: pandemic influenza preparedness and response: a who guidance document. world health organization correlation between healthcare workers' knowledge of influenza vaccine and vaccine receipt factors influencing update of influenza vaccination among hospital-based healthcare workers nurses' contacts and potential for infectious disease transmission influenza immunization: improving compliance of healthcare workers uptake of influenza vaccine by healthcare workers in an acute hospital in ireland low acceptance of vaccination against the pandemic influenza a(h n ) among healthcare workers in greece behviours regarding preventive measures against pandemic h n influenza among italian healthcare workers willingness of hong kong healthcare workers to accept pre-pandemic influenza vaccination at different who alert levels: two questionnaire surveys positive attitudes of french general practitioners towards a/ h n influenza-pandemic vaccination: a missed opportunity to increase vaccination uptake in the general public? vaccine siva n: incidence of swine flu in england continues to fall, but winter surge is predicted impact of severe acute respiratory sundrome and the perceived avian influenza epidemic on the increased rate of influenza vaccination among nurses in hong kong exploring determinants of acceptance of the pandemic influenza a (h n ) vaccination in nurse the public's acceptance of novel vaccines during a pandemic: a focus group study and its application to influence h n . emerg health threats j will the community nurse continue to function during h n influenza pandemic: a cross-sectional study of hong kong community nurses? general practice and pandemic influenza: a framework for planning and comparison of plans in five countries primary care physicians in hong kong and canada-how did their practices differ during the sars epidemic? widespread public misconception in the early phase of the h n influenza epidemic influenza vaccination among primary healthcare workers which determinants should be targeted to increase influenza vaccination uptake among healthcare workers in nursing homes? vaccine influenza vaccination among registered nurses: information receipt, knowledge, and decision-making at an institution with a multifaceted educational program promoting uptake of influenza vaccination among health care workers: a randomized controlled trial health care worker, vaccinate thyself: toward better compliance with influenza vaccination this study was supported by the research fund for the control of infectious diseases (rfcid), food and health bureau, hong kong sar government. we thank ting gao in data entry and her assistance in analysis of data. we also thank louisa lau for coordination with centres* of the community nursing service. we especially thank all nurses and nursing managers of the community nursing service of the hospital authority who participated in this study. all authors were involved in the design of the project. the survey tool was designed by sysw and elyw. the data collection, analysis and the results interpretation were carried by sysw and elyw in consultation with the team. the first draft of this article was composed by sysw and was revised critically by all authors. all authors have approved the final version of the manuscript. the authors declare that they have no competing interests. key: cord- - m spnxj authors: kim, jean h.; lo, fung kuk; cheuk, ka kin; kwong, ming sum; goggins, william b.; cai, yan shan; lee, shui shan; griffiths, sian title: knowledge of avian influenza (h n ) among poultry workers, hong kong, china date: - - journal: emerg infect dis doi: . /eid . sha: doc_id: cord_uid: m spnxj in , a cross-sectional survey of poultry workers in hong kong, china, showed that workers had inadequate levels of avian influenza (h n ) risk knowledge, preventive behavior, and outbreak preparedness. the main barriers to preventive practices were low perceived benefits and interference with work. poultry workers require occupation-specific health promotion. in , a cross-sectional survey of poultry workers in hong kong, china, showed that workers had inadequate levels of avian infl uenza (h n ) risk knowledge, preventive behavior, and outbreak preparedness. the main barriers to preventive practices were low perceived benefi ts and interference with work. poultry workers require occupationspecifi c health promotion. i n , a zoonosis in humans caused by a highly lethal strain of avian infl uenza virus (h n ) was reported in hong kong. live-poultry markets were the source of this outbreak ( ) . as one of the world's most densely populated regions ( , persons/mile [> , persons/km ]) ( ), hong kong is a city at high risk for a large-scale outbreak of avian infl uenza caused by live poultry in large-volume wholesale markets and within neighborhood wet markets (open food stall markets). because members of the average household in hong kong shop in wet markets on a habitual basis, these markets are located in the most densely populated areas ( figure) and are commonly multistory complexes or in basement levels of shopping centers. because poultry workers are a potential bridge population ( , ) , the government has instigated voluntary avian infl uenza training since that reviews regulations for workplace disinfection, waste disposal, poultry storage, and personal hygiene measures ( , ). despite occupational risk for exposure to avian infl uenza ( , ) , there have been few studies of poultry workers ( ) ( ) ( ) ( ) ( ) . most studies were conducted in rural settings in developing countries ( ) ( ) ( ) ( ) , but fi ndings cannot be readily extrapolated to cities such as hong kong because of differences in food-handling practices and occupational settings. knowledge, perceptions, and work practices of live-poultry workers in hong kong have not been examined. therefore, a survey of these workers is timely and warranted, given confi rmed persistence of avian infl uenza in asia. ( ) the study an anonymous, cross-sectional survey was conducted during june-november . interviewers approached licensed live-poultry retail businesses in wet markets and wholesale establishments. the fi nal sample was poultry workers ( retailers and wholesalers; response rate . %). respondents were asked about their demographics, past month's work and preventive behavior, and avian infl uenza-related knowledge on the basis of a world health organization factsheet ( ) . we asked perception questions based on the health belief model and the likelihood of adopting certain behavior patterns in the event of a local bird-to-bird or bird-to-human outbreak of avian infl uenza. summative scores were computed for avian infl uenzarelated knowledge, current preventive behavior patterns, outbreak preparedness, and various perception domains. higher scores refl ected more benefi cial levels of each domain. unconditional multilevel regression indicated no evidence of clustering effect by poultry market. standard multivariable linear regression was conducted by using sas version . . (sas institute, cary, nc, usa) with knowledge, practice, and preparedness scores as outcomes and potential predictors showing p< . in unadjusted analyses as input variables. distribution of standardized residuals and their association with predicted values were examined to assess model assumptions. most ( , . %) respondents were men - years of age, of whom ( . %) had worked a mean of . years in the poultry industry. respondents showed low mean summative scores for knowledge of avian infl uenza (online appendix incorrectly believed that a human vaccine for avian infl uenza was available. most ( , . %) respondents were familiar with infl uenza-like symptoms of avian infl uenza virus (h n ) infection such as fever, but fewer workers were aware of respiratory and gastrointestinal symptoms of virus infection. the internet and other sources (e.g., health talks) of information about avian infl uenza were strong independent predictors of greater knowledge. however, training did not result in higher knowledge levels. poultry workers reported low-to-moderate levels of compliance with hand hygiene and other preventive measures (ranging from . % [ ] using eye protection to . % [ ] using handwashing with soap after slaughtering poultry). working in the poultry industry ≥ years, lower perceived barriers to preventive behavior, and retail poultry work were independent predictors of higher preventive behavior scores. with regard to avian infl uenza-related perceptions, lack of training ( , . %) and the view that compliance with all infection regulations is diffi cult during peak hours ( , . %) were the most frequently cited barriers to adoption of preventive behavior. a total of ( . %) workers believed that face masks reduced business, and ( . %) believed that vaccination was expensive. low anxiety about illness was reported by ( . %) respondents. in the event of a local outbreak, workers expressed various levels of acceptance for precautionary actions, ranging from . % ( ) for reducing work hours to . % ( ) for seeking medical care for infl uenza-like symptoms. ninety-six ( . %) respondents anticipated taking oseltamivir. greater perceived benefi t of preventive behavior was the strongest independent predictor of higher preparedness scores (online appendix table , wwwnc.cdc. gov/eid/article/ / / - -ta .htm). similar to other regions ( ) ( ) ( ) ( ) , poultry workers in hong kong showed low risk perceptions for avian infl uenza, inadequate knowledge, and a wide range of compliance with preventive measures. because training ( ) was not associated with overall preventive behavior or preparedness, there may be an unmet need for occupationspecifi c health information. higher levels of knowledge demonstrated by workers who accessed health information sources (e.g., internet) that provide detailed information suggest that comprehensive, occupation-relevant information should be more widely accessible. however, occupational practices of animal workers might not be amenable to change solely on the basis of improvements in knowledge. only ( . %) respondents reported that poultry workers could realistically adhere to all government guidelines ( ) . interference with work, high cost, and reduction of business were repeatedly cited as impediments to the adoption of preventive behavior. even in the event of local outbreaks of avian infl uenza, most workers were not amenable to actions having adverse economic effects such as reducing work hours. animal workers are thereby unlikely to widely adopt preventive behavior if these measures confl ict with their economic interests. despite the ongoing government regulations regarding avian infl uenza in hong kong ( ), a complete ban on live poultry is unrealistic because of the culturally entrenched demand for fresh poultry. increasing knowledge and risk perceptions while simultaneously reducing occupational barriers to preventive behavior thereby continues to be the cornerstone of effective zoonotic infection control among animal workers. implications of these fi ndings extend to other poultryborne pathogens, such as campylobacter spp. and emerging infectious diseases • www.cdc.gov/eid • vol. , no. , december salmonella spp., which share common preventive measures. close adherence to workplace measures will likely reduce outbreak risk for other poultry-borne diseases. therefore, a framework for greater integration of risk management strategies and worker education of these poultry-borne infections tailored to the local context is worthwhile and cost-effective. in the spirit of the one health commission, which calls for an integrated, interdisciplinary approach to human-veterinary-environmental health challenges ( ), the fi ght against global pandemics, such as those of avian infl uenza virus (h n ), necessitates greater dialogue and collaborative leadership between governments and livestock industries. development of realistic occupational safety measures is an ongoing challenge for national governments. confi rmed human cases of avian infl uenza a (h n ) census and statistics department, the government of the hong kong special administrative region. key statistics of the population census. hong kong: the government wet markets: a continuing source of severe acute respiratory syndrome and infl uenza? risk of infl uenza a (h n ) infection among poultry workers, hong kong, - training for prevention of avian infl uenza risk for infection with highly pathogenic infl uenza a virus (h n ) in chickens case-control study of risk factors for avian infl uenza a (h n ) disease, hong kong knowledge, attitudes, and practices of avian infl uenza, poultry workers poultry-handling practices during avian infl uenza outbreak attitudes, and practices regarding avian infl uenza (h n ) avian infl uenza risk perception among poultry workers environmental sampling for avian infl uenza virus a (h n ) in livebird markets avian infl uenza ("bird fl u"): fact sheet one health commission we thank the poultry workers for participating in the study and terry wong for assisting with preliminary data collection. key: cord- -ugc ce authors: ching, frank title: bird flu, sars and beyond date: - - journal: years of medicine in hong kong doi: . / - - - - _ sha: doc_id: cord_uid: ugc ce in the politically sensitive year of , hong kong experienced an outbreak of avian flu when the deadly h n virus unprecedentedly jumped the species barrier from chickens and infected human beings. hong kong decided to slaughter over a million chickens, and the virus was stopped in its tracks. in , hong kong was the epicenter of the sars pandemic, which originated in guangdong province. the faculty of medicine played key roles in both instances, with its microbiology department successfully identifying a novel coronavirus as being responsible for sars. hong kong learned from its experience and took action to combat the emergence of new infectious diseases. such vigilance paid off in , when swine flu swept the world, and in , when a novel avian flu h n emerged in china. all the preparations to entrench medical autonomy in hong kong after the british departure did little to help the freshly minted hong kong special administrative region deal with the first medical emergency in the post-colonial period: an outbreak of what was widely called the bird flu, which for the first time saw the virus jump the species barrier to infect human beings, sickening people, of whom six died, an inordinately high mortality rate of %. hong kong gained the distinction of being the only place where this event, which scientists had thought could not happen, actually happened. it was previously thought that avian influenza viruses could not directly attack humans, requiring a mammalian intermediary such as a pig, wherein host adaptation or genetic reassortment could take place, before a virus capable of infecting humans would emerge. that was thought to have been the pattern of previous pandemics, such as the asian flu of and the hong kong flu of , which together claimed more than . million human lives. as for the great flu of , which infected an estimated million people worldwide-about a third of the world's population at the time-and killed - million people-there is still no agreement on its origins, although the u.s. surgeon general alluded to an asian origin saying, "some writers who have studied the question believe that the epidemic came from the orient." in march, , the first signs of trouble in hong kong appeared when chickens on a yuen long farm started to die. then those on a second farm started dying, and a third, with about , birds succumbing to influenza. although farmers were concerned, health authorities were not too worried because the virus from which the chickens suffered was never known to cross the species barrier and infect humans. that is, not until two months later. to coordinate, and to articulate to the public what is going on," fukuda said. "meet public expectations and marshal all scientific expertise you need. make sure agriculture was involved. dr. margaret chan was clearly overseeing everything." shortridge himself felt subsequent events justified the cull. "the last human case of h n disease was recognized the day before the commencement of the slaughter on december, vindicating the controversial slaughter policy," he wrote. "it is reasonable to believe that this intervention prevented an incipient pandemic progressing to an actual pandemic and thus a pandemic was averted. the h n / virus was possibly one or two mutational events from achieving pandemicity. however, as with all measures that successfully prevent an adverse outcome there is no definite way of proving their efficacy." the unusual clinical severity and high mortality of infected patients in the outbreak of avian influenza h n in hong kong was first reported in the lancet in february by yuen kwok-yung (k.y. yuen) of hong kong university's department of microbiology. he was the lead writer, whose co-authors included k.f. shortridge and malik peiris. yuen had attended to h n patients and devised a rapid diagnostic test known as rt-pcr used in testing the respiratory secretions from these patients. this was the first time that the test was used for rapid diagnosis of such patients in a clinical setting. he also analyzed the case notes of patients, ranging in age from to . "whether avian viruses can infect human beings directly or need to reassort in an intermediate host (e.g., pigs) is a matter of debate," he wrote, adding: "until recently, a purely avian virus had not been isolated from people with respiratory disease, although conjunctivitis caused by an avian h virus has been reported." while decisions regarding the slaughter of chickens were made by the government, the university played a major role. this was known to the outside world as well. thus, the following year, when thailand announced the winner of the prince mahidol award for outstanding achievements in medicine and public health, the award was shared jointly by margaret chan, the director of health, and professor shortridge. in the aftermath of the events, tight surveillance of the live poultry retail markets revealed that the highly pathogenic h n / virus was no longer detected. however, the precursor viruses remained, including the h n -like virus in the guangdong goose identified in and other viruses in quails. live chickens continued to be sold in hong kong but the government after instituted a policy of central slaughter of geese and ducks. for three years, hong kong's retail markets remained free of the h n virus. but in , the h n virus was back. on april , the government announced that it had isolated goose/ -like h n virus from a chicken cage in the poultry stall of a market, but suggested that this mild type of virus would not pose a major threat to public health. however, the surveillance program of the university detected a new strain of h n virus and the sample was confirmed by the world health organization as having the potential to be highly pathogenic. the viruses were initially detected in apparently healthy chickens but, not long afterward, the chickens began dying in one market after another, although there were no human victims. professor k.y. yuen, who had been chair of infectious diseases since and was a member of the consultation committee of the health and welfare bureau, held detailed discussions with lily yam, secretary for environment and food, on measures to deal with the outbreak (fig. . ) . he fully supported her decision to make a pre-emptive move and slaughter more than a million chickens, ducks and geese to prevent further reassortments, possibly into pathogens that can threaten people. the influenza research team, established after the h n outbreak in , was led by professor shortridge and included dr. malik peiris and dr. guan yi, as well as ten local research assistants, all of whom worked closely with the government to identify new influenza viruses and stop them before they could infect humans. the team also cooperated with the world health organization, the u.s. national institute of health and other international health bodies. yam explained that the slaughter was ordered "to avoid the possibility, no matter how remote, of this particular strain combining to form a new strain that may affect human beings." k.y. yuen proposed a monthly rest day for retail markets, when all unsold poultry would be killed and the markets cleaned, left empty for the day, then restocked the following day. the measure was adopted by the government. shortridge and his colleagues found that virus isolation rates were significantly lower following the rest day. the pre-emptive depopulation decision halted the continuing reassortment of viruses within the poultry population and prevented the emergence of any that could attack humans. in , another incident occurred that confirmed the rapid adaptation of the h n virus. in early january, a new subset of h n -like viruses was detected in the retail markets. they were isolated from dead chickens. subsequently, a series of reports were received of chicken farms found to be infected as well as in chicken stalls in retail markets. the farms were quarantined and depopulated. a total of , chickens were slaughtered. with the cooperation of vigilant operators of chicken farms, disease recognition can take place earlier, before the chickens went to market. as shortridge observed, it was now possible to have a higher level of baseline preparedness for the next influenza pandemic. at the end of , unknown to anyone in hong kong, another deadly virus was circulating in neighboring guangdong province, propagating a disease that had no name but which was preliminarily dubbed atypical pneumonia in china and later renamed severe acute respiratory syndrome, or sars, by the world health organization. the first cases emerged in foshan city in mid-november. it spread within the province to heyuan and zhongshan. it was difficult to know what was going on in the mainland, especially where a sensitive issue like the emergence of a new disease was concerned. no announcements were made either by beijing or by local authorities in guangdong province. however, the controlled media did, at times, publish articles from which some information could be gleaned. thus, guangdong newspapers in early january published a handful of articles denying the existence of any epidemic but, by doing so, enhanced speculation of a deadly new disease. on january an article appeared in heyuan daily headlined "epidemic is only a rumor." in guangzhou, news express ran an article "no reason to worry" on january and "heyuan back to normal" on january . such articles were meant to reassure the public that the situation was under control and that there was nothing to worry about. but the articles themselves were not that reassuring. thus, the heyuan daily article described panic buying of drugs, with long lines at pharmacies. it said that the "terrifying rumor of a serious infectious disease" had resulted in a rush to purchase certain antiviral tonics. "this irrational purchasing has driven prices of these drugs to ridiculous levels: a tonic that usually costs yuan now costs yuan. antibiotics have also become more expensive, the price rising to yuan. yet no matter the price, as of p.m., these medicines were sold out at most pharmacies. until yesterday morning there were long lines waiting to buy these drugs with customers purchasing up to boxes each." the article also revealed that parents were keeping their children at home rather than sending them to kindergarten. "in the central kindergarten, two classes contained a total of kids, less than half the usual attendance," the article said. "kindergarten officials said they had also heard the rumors of a disease but didn't believe it. but just in case, they added, they had prepared a cold elixir tea to ward off any sickness." so even teachers who "didn't believe" the rumors were taking precautions. as for the disease itself, the article had this to say: "people's hospital of heyuan received two patients from zijin hospital on the fifteenth of last month. the patients were transferred to shenzhen and guangzhou. specialists from hospitals in guangzhou were sent to heyuan to help in the treatment. the hospital director said that after the meeting of provincial experts it was proven that the disease is a very common disease: atypical pneumonia. this disease is not infectious and is caused by changing weather. the symptoms are high fever, coughing and spots in the lungs. this disease is not similar to any communicable disease identified by the government so there has been no reason to report it to provincial authorities." so it seemed that heyuan was not able to look after its own patients and had to send them to other cities, and had to seek help from specialists in guangzhou. also, while saying that "the disease is very common," the article seemingly contradicted itself by saying, "this disease is not similar to any communicable disease identified by the government." there was a mysterious illness about, not just a rumor. a team of health experts had been sent to heyuan in mid-december and, on january , , these health personnel diagnosed the disease as an infection caused by a certain virus. "guangzhou is fighting an unknown virus," the mainland media reported. on january , the guangdong health department received a "top secret" document from a government health committee. however, because no one with sufficient security clearance was there, the document, which contained information about a new pneumonia-like illness spreading in the region, lay unread for three days. eventually, a bulletin was sent to hospitals across the province, but by then many health workers were on vacation because of holidays to celebrate the chinese new year, which fell on saturday, february . the chinese public, and the rest of the world, was kept in ignorance. under chinese law, any occurrence of infectious diseases should be classified as a state secret before they are "announced by the ministry of health or organs authorized by the ministry." that is to say, until the government made the information public, any doctor or journalist who disclosed information on the disease was liable to prosecution for leaking state secrets. on february , reports about a "deadly flu" began to be sent via text messages on mobile phones in guangzhou. in the evening, words like bird flu and anthrax started to appear on some local internet sites. day, two major guangzhou newspapers, the nanfang daily and the yangcheng wanbao, carried short news reports about a "mysterious illness" that had hit the hospitals in guangzhou. the next day, february , a delegation of experts from the ministry of health and the chinese center for disease control and prevention (china cdc), led by the vice minister of health and the deputy director-general of health, went to guangdong. on february , a circular appeared in the local media that acknowledged the presence of the disease and listed some preventive measures, including improving ventilation, using vinegar fumes to disinfect the air, and washing hands frequently. responding to the advice, residents in guangzhou and other cities cleared pharmacy shelves of antibiotics and flu medication. in some cities, even white vinegar was sold out. the panic spread quickly in guangdong, and was also felt in other provinces. the information blackout imposed by the mainland meant that the health authorities in hong kong were kept in ignorance of what was going on in neighboring guangdong. it wasn't until february , , when six newspapers in hong kong carried reports on the atypical pneumonia outbreak that hong kong's director of health, dr. margaret chan, and secretary for health, welfare and food, dr. yeoh eng-kiong, became aware of the epidemic next door. it was also on february that the who country office in beijing received an email message describing a "strange contagious disease" that had "already left more than people dead in guangdong province in the space of one week." the global public health intelligence network of the who also picked up media reports of an unusual epidemic of fatal pneumonia-like illness in guangdong. february was the first working day for many people after the weeklong chinese new year holiday. on that day, the who representative in china, dr. henk bekedam, received reports about an alarming outbreak in guangdong province. the son of a former who staff member sent an email to alan schnur, the communicable disease team leader of who china: "am wondering if you would have information on the strange contagious disease (similar to pneumonia with invalidating effect on lung) which has already left more than people dead in … guangdong province, in the space of one week. the outbreak is not allowed to be made known to the public via the media, but people are already aware of it (through hospital workers) and there is a 'panic' attitude, currently, where people are emptying pharmaceutical stocks of any medicine they think may protect them." mr. schnur forwarded the email at once to the ministry of health, and sought information. he added that the american embassy had passed on a similar rumor about a strange disease that was causing bleeding and many deaths in guangzhou. once the hong kong government learned from the newspapers about this health crisis, it attempted to obtain additional information, aware that previous waves of diseases, such as the global pandemics of and , had entered hong kong from guangdong province before spreading into the rest of the world. the department of health tried to telephone health officials in guangdong to find out what exactly the position was, but it failed to reach anyone in authority. when dr. e.k. yeoh asked dr. chan about the outbreak in guangdong, she told him about the department's failure to obtain any response to its enquiries. he then asked her to contact the ministry of health in beijing, since this was the established channel of communication between hong kong and the chinese government where infectious diseases were concerned ( fig. . ). it turned out that under the policy of "one country, two systems," only the central government was supposed to communicate with hong kong and not the provincial government in guangdong. dr. chan then successfully contacted the director general of the department of international cooperation of the ministry of health by telephone and expressed concern about the reported epidemic in guangdong. the director general promised to look into the matter. the following morning, the guangzhou city government held a press conference at which the director of the bureau of health, huang jiongjie, explained the situation in the provincial capital. director huang said that towards the end of , atypical pneumonia cases were reported in certain parts of guangdong province. to date, he said, more than a hundred cases had been reported in guangzhou, with many of the patients being healthcare workers. there had been two deaths. despite its quick onset, he said, the risk of fatality is low. there was, he said, no need to panic. in the afternoon, the guangdong provincial government held its own press conference. health officials reported a total of atypical pneumonia cases in the province, with five deaths. but they, too, spoke reassuringly about how the situation was under control although they acknowledged that there were no effective drugs to treat the disease and that the outbreak was only tentatively contained. a third of the cases were health workers who contracted the disease while caring for patients. that same information, that there had been about cases and five deaths in guangdong province as a result of an outbreak of acute respiratory syndrome, was also passed on to the who by the chinese ministry of health. professor yuen kwok-yung, head of the microbiology department, had kept his ear to the ground to find out what was going on in hong kong's neighborhood. unlike the government, which did not bother to monitor what appeared in guangdong newspapers, professor yuen, also known as k.y., was very concerned about the increasing reports in the media about unusual outbreaks of mysterious diseases. university of hong kong researchers were ahead of the government, which was oblivious to what hints had appeared in the mainland press. they, too, sought additional information but they, unlike government officials, had the necessary contacts. as professor yuen subsequently explained to the legislative council select committee set up to look into the government's handling of the disease, the microbiology department convened a meeting attended by four persons: k.y. yuen, the head of department, professor malik peiris, dr. guan yi and dr. b.j. zheng. at the meeting, guan yi expressed his concern that the atypical pneumonia outbreak in guangdong might be linked with h n influenza, as had happened in hong kong in (fig. . ) . he proposed a more in-depth field investigation to ascertain the infectious agents responsible for the outbreak by conducting a foray into guangzhou to find out what was actually going on and, if possible, to bring back specimens from patients suffering from this mysterious ailment for analysis in hong kong. the consensus at that meeting was that dr. guan and dr. zheng should try to contact authorities in guangzhou to facilitate the investigation (fig. . ). as peiris said, "we knew the disease was going to come over to hong kong," so it was vital to learn as much as possible before it arrived. guan and zheng were both from the mainland and knew its culture and its people. so, when a mysterious disease was reported in guangdong, it was natural that they were the ones to plunge deep into the heart of the infected areas and to shine a light into the dark corners. they left the following day, february . peiris's role was to supervise the virological investigations into the patient specimens. he would also liaise with researchers in other countries. yuen himself focused on hong kong. ever since the avian flu outbreak in hong kong, the department of microbiology had conducted frequent exchanges with mainland doctors and scholars. when this mysterious new disease emerged, researchers both in hong kong and the mainland suspected that it was again some form of bird flu. during their visit, dr. guan and dr. zheng met professor n.s. zhong (鐘南山), or zhong nanshan, a prominent educator and researcher who was head of the respiratory research center at the first affiliated hospital, guangzhou medical college. dr. zheng knew him personally, so it wasn't difficult to arrange to discuss the atypical pneumonia situation with him. dr. zhong, who had received his early training in beijing medical university and had done advanced work at st. bartholomew's hospital in london and the university of edinburgh medical school, was in charge of the management of atypical pneumonia cases at his hospital ( fig. . ). during their visit, dr. zhong told the two hong kong researchers that the atypical pneumonia outbreak might be caused by flu-like viral infection because all routine laboratory examinations for infectious agents were negative. he suggested collaboration between his institution and the university of hong kong and agreed to provide specimens from patients with atypical pneumonia for viral isolation and identification. while strictly speaking this could be interpreted as a violation of china's state secrets laws, it also could be labeled an "academic exchange" between health specialists in the mainland and hong kong. obtaining the specimens was in itself risky, since it meant direct physical contact with patients suffering from the mysterious disease. in the hospital of the guangzhou institute of respiratory diseases, the two hong kong doctors, wearing full protective gear, walked amid the patients, all in critical condition, accompanied by a nurse. some sense of what happened is provided by this account: "she [the nurse] elevated the back of the man's bed, removed his oxygen mask, and ordered him to open his mouth. tentatively reaching a wooden stick with a q-tip-like bulb at the end into the oral cavity, the nurse dabbed at the patient's tongue twice, removed the swab, and handed it to guan yi. he broke the top of the stick and dropped the swab into a vial of medium. he didn't say anything, but he could already see that this wasn't going to work. in order for it to be an effective screening, he would need mucus and phlegm from further down the patient's throat, as well as some nasal aspiration. the nurse was too frightened to gather anything but the faintest of saliva samples." guan yi decided to take over and so, at the next station, he asked the nurse to step aside as he held a female patient up, ordering her to open her mouth, and then began slapping her back gently to encourage her to expectorate mucus. "this time the swab was pressed so far down the patient's throat that when guan removed it, it was coated with a satisfactory blob of mucus that glistened under the white lights. he managed to take twelve swabs, each of which he sealed in a vial of suspension medium so that they appeared almost like miniature moth cocoons preserved in formaldehyde." so the specimens were obtained and brought back to the microbiology department to be analyzed by malik peiris and his associate, chan kwok-hung (陳 國雄), or k.h. chan. in fact, dr. zhong subsequently said that samples were not given out to other researchers simply because they didn't ask. professor yuen kept the hong kong government informed of his department's activities through telephone calls to director of health margaret chan. the microbiologist told her about the investigation into the possible infecting agent responsible for the atypical pneumonia outbreaks in guangdong and of the visit to guangzhou by two members of his department and their return with specimens. he also conveyed to her his concern that large numbers of healthcare workers were being infected. so the university and the government were in close contact from the earliest days. munity acquired pneumonia. all hospitals were required to report such cases. nineteen cases were identified in february. hong kong university researchers tried to isolate the virus causing the outbreak in guangdong. they were the only ones in hong kong with specimens, but then they hit a stone wall. the specimens brought back were inoculated into chicken embryo and other cell lines. after several days, various viruses were isolated, including the h n influenza virus, a virus that causes the common cold and one that causes respiratory infections called metapneumovirus, but there was nothing that was identifiable as the pathogen responsible for the guangdong outbreak. because bird flu, especially of the h n variety, was the chief suspect, attempts to cultivate the specimens used cell lines set up for this purpose. but they failed. a predisposition to suspect avian flu was totally natural. after all, on february , hong kong reported to the world health organization another outbreak of h n when the avian flu virus was detected in a nine-year-old boy, whose family had been visiting fujian province when he fell ill. his father had died two days previously from an infection with the same virus, and his sister had died in fujian earlier in the month, but was not tested for the virus. the who, too, saw a possible link between avian influenza and the outbreak in guangdong. however, by mid-february, malik peiris was thinking of testing for other virus groups, but was hobbled by the limited resources of his modest virology lab. he made enquiries with overseas colleagues regarding techniques for picking up other virus groups, such as coronaviruses, hantaviruses and adenoviruses. meanwhile, guan yi and b.j. zheng continued to travel to guangzhou to collect additional samples from patients. but it wasn't long before it became unnecessary to travel to guangdong to look for the virus. the virus had come to hong kong. the date it happened can be pinpointed. on february , dr. liu jianlun, a -yearold professor of nephrology from a teaching hospital in guangzhou, arrived in hong kong and checked into the metropole hotel. dr. liu had contact with patients suffering from atypical pneumonia and then developed a fever and cold, which was treated by antibiotics. though he still felt unwell, he decided to go ahead with his hong kong trip on february to take part in the wedding of his nephew. after arriving in hong kong, dr. liu and his wife had lunch with his sister and brother-in-law in a restaurant near the mong kok railway station. it was their son who was getting married. then he went shopping in central with his brother-in-law and had dinner in his home before going to the metropole hotel in kowloon to spend the night. the next morning, february , a saturday, he walked into the accident and emergency department of kwong wah hospital, which was close to his hotel. he told hospital staff that he had been in contact with patients suspected to have atypical pneumonia during february - and had developed flu-like symptoms with sharp chest pain on february . chest x-rays had showed left lower zone haziness. he said he treated himself with antibiotics (levofloxacin) and penicillin and improved. he said he had fully recovered before leaving for hong kong. but in hong kong, his fever came back and he had shortness of breath. the accident and emergency department realized this was a serious case and requested an immediate transfer to an intensive care unit. dr. watt chi-leung (屈志亮), icu director, was aware of reports of an epidemic in the mainland and put dr. liu in isolation. he also instructed icu staff to put on n surgical masks, gloves and gowns when caring for this patient. dr. watt also asked icu staff to take tamiflu as a precautionary measure. on february , there was an unexpected telephone call from guangzhou. fig. . ) . at the hospital, they went over in considerable detail with hospital doctors the clinical history, examination findings, case notes, computer records, chest x-rays, laboratory results and infection control measures relating to the patient. so the faculty of medicine was involved in the treatment of the very first sars patient from mainland china, who became known as patient zero, an extremely infectious patient who brought sars to hong kong and, from hong kong, the disease rapidly spread around the world. it is believed that dr. liu infected other guests in the hotel and, through them, something like , people in various countries became infected in less than four months as a result of travel by these hotel guests. this showed how rapidly a disease can spread in the twenty-first century. as long as the disease was bottled up in china, its impact was limited to "report on a sars patient from guangzhou who was admitted to kwong wah hospital," sc paper no. a . one country. but as soon as it spilled over into hong kong, a hub of international air travel, it quickly spread around the world. professor yuen himself participated in the treatment of the liu case. he initiated a course of ribavirin, a broad-spectrum viral agent, which is effective against respiratory, hepatitis and hemorrhagic fever viruses. despite all efforts, dr. liu died on march , ten days after he sought treatment at kwong wah hospital. by then, his brother-in-law, y.p. chan, had been admitted to kwong wah for exactly the same condition. as professor yuen said, the illness of the brother-in-law was a turning point, since another family member had been infected by the same mysterious illness. "we had," he said, "a real crisis on our hands." time was pressing. on march , the world health organization issued a global alert about cases of atypical pneumonia. it recommended that "patients with atypical pneumonia who may be related to these outbreaks be isolated with barrier nursing techniques." at the same time, who also recommended that "any suspect cases be reported to national health authorities." three days later, it issued a rare emergency travel advisory calling the disease "a worldwide health threat." it also gave the mystery ailment a name, severe acute respiratory syndrome (sars). for the special administrative region, it was an unfortunate choice of names, tarnishing the image of hong kong at best and, at worst, suggesting that the disease and hong kong were somehow synonymous. hong kong suggested a name change to the who but eventually gave up such efforts. on march , who released a list of "affected areas" with local transmission of sars. hong kong was on that list. however, as far as the who was concerned, sars was not named after hong kong. indeed, the world health body, in describing the new disease, said it was "first recognized in late february, , in hanoi vietnam." with the sars epidemic's arrival in hong kong, the university's department of community medicine became closely involved. professor anthony j. hedley, the chair professor of community medicine since , had focused on issues such as smoking, air pollution and other noninfectious health problems. sars, of course, was quite different, with its rate of infection and case fatality rate yet unknown. hedley turned to imperial college, london, for help. in an email to roy m. anderson, the head of the department of infectious disease epidemiology, he acknowledged that his department didn't have much experience in this area. i know your work, hedley said, could i persuade you to get interested in sars? could you come over and visit us? ( fig. . ). anderson needed little persuasion. he had already been asked by david heymann, deputy director of the world health organization, to be a member of its sars emergency committee. his department had a lot of experience dealing with past epidemics, ranging from aids to foot-and-mouth to influenza. as it was, heymann had asked anderson to join him on a trip to beijing to talk to the chinese authorities about sharing data on how the epidemic started, what progress there was and control measures. soon, anderson was on a plane bound for hong kong. beijing came next. in hong kong, hedley arranged for anderson to meet his colleagues, including gabriel leung, who established and directed the university's infectious disease epidemiology group, and dr. margaret chan, the director of health. together, they worked out a protocol for capturing data, analyzing the data and some public health interventions. so the department was collaborating with both imperial college and with the hong kong government. the department, anderson said, "played an important role in helping the hong kong government construct additional databases of cases, their contacts and basic demographic and epidemiological data from the midpoint of the epidemic onwards." more trips followed for anderson and members of his team. soon, imperial college and hku scholars were writing papers together. one early paper, whose principal researchers were anderson and christl a. donnelly, also of imperial college, was somewhat controversial, asserting that the case fatality rate was significantly higher than health authorities had thought, possibly up to % in people and above, and . % in younger people. as the new york times reported, this was the first major epidemiological study of the disease. the paper's authors included seven imperial college experts, seven specialists from the department of community medicine of the university of hong kong, two from the hong kong department of health, two from the hong kong hospital authority and one from the chinese university of hong kong. they explained that estimating fatality rates by simply "dividing the current cumulative number of deaths by the current cumulative number of hospital admissions" was not satisfactory because "among patients still recorded as being in hospital, it is impossible to ascertain who will eventually die or be discharged." because of the public health importance of the article, the lancet posted it online on may , , more than two weeks before it appeared in the journal itself. the imperial college-hong kong university collaboration continued after the re-emergence of sars in mainland china in . in a paper where anderson was the principal author, the group reviewed the understanding of the epidemiology, transmission dynamics and control of the aetiological agent of sars. it concluded that the low transmissibility of the virus, combined with the onset of peak infectiousness following the onset of clinical symptoms of disease, "transpired to make ibid. simple public health measures, such as isolating patients and quarantining their contacts, very effective in the control of the sars epidemic." if the time from infection to symptoms is about two days and the time from infection to peak infectiousness is also two days, then "by the time a patient reports to a physician it's too late to quarantine him" because transmission has already occurred, anderson explained. but, with sars, "the incubation period from infection to first fever is five days, the time from infection to peak infectiousness is about days, so you had a long interval and if you isolated or quarantined that patient you could stop transmission dead." that, he said, was essentially what was done since roman times with ships arriving at ports, and "sailors were put in quarantine until they were certain that they were not transmitting anything obnoxious from their travels." anderson observed that the department of community medicine, which was subsequently absorbed into the school of public health, had been transformed by the sars experience. "what sars did," he said, "was to shift its attention a little bit more to infectious diseases. and infectious diseases epidemiology is slightly different-it involves transmission dynamics, it involves contact tracing, we have a primary case, you had to understand who that person has had contact with, so it has influenced the way the people thought about infectious diseases and how best to study them." speaking of his own institution, anderson said, "we are a very quantitative group with a high computational, mathematical and statistical capability, so we probably switched them on a little bit towards more quantitative side of understanding transmission and control." the paper on the epidemic case fatality rate, he said, may well have been one of the department's first infectious disease epidemiology papers, which was followed by many more. "when you deal with noninfectious diseases, you can take your time," he observed. "epidemics happen quickly and when they start to take off they grow exponentially. the sars epidemic had a doubling time of about five to seven days, so things were moving very, very quickly. a very large number of staff in the department was switching from their normal research interest to thinking how to combat and study sars." this transformation, he said, was successful. "some very high quality work has been coming out of there in the last years," he said, which has had "a very substantial influence internationally." as soon as the emergency travel advisory was issued in mid-march, the who set up a network of scientists from laboratories around the world to try to identify the causal agent and develop a diagnostic test, similar to a network for influenza set up by klaus stohr. the laboratories were in canada, france, germany, japan, the netherlands, singapore, the united kingdom, the united states and, of course, hong kong. all were approached by telephone during the weekend of march - and all agreed to participate and to observe the who's ground rules. the purpose of the network was to unite laboratories with different methods and capacities to rapidly fulfill all postulates for establishing a virus as the cause of the disease. scientists agreed to share results in real time via a secure website and discuss findings in daily conferences. as klaus stohr wrote, "laboratories in the influenza network ruled out all influenza virus strains and other known causes of pneumonia from samples taken in hanoi, singapore and hong kong. sars looked increasingly like a new disease." of the laboratories, three were in hong kong. these belonged to the hong kong government, the university of hong kong and the chinese university of hong kong. at hong kong university, the team included medical technologist chan kwok-hung, pathologist john nicholls and leo poon lit-man. the hong kong university virology lab was the smallest, with only about six people, easily dwarfed by the government's virology lab, not to say the u.s. cdc's lab, where hundreds of people worked. in other words, the odds were stacked against malik's team in the race to identify the sars virus. dr. chan set up cell lines for the testing of specimens, dr. poon helped develop molecular diagnostic tools for fishing out unknown pathogens, and dr. nicholls (fig. . ) used electron microscopy to help identify viruses. k.y. yuen did pcr tests on the positive cell culture with cytopathic effect to exclude the presence or contamination by any bacteria that may cause atypical pneumonia, including chlamydia and mycoplasma. the situation in hong kong was worsening. by march , hospital workers and relatives of what authorities believed to be the index patient were diagnosed with atypical pneumonia, now renamed sars. most were in the prince of wales hospital, the teaching hospital of the chinese university of hong kong, and four were in intensive care. of the cases, were doctors, nurses, and other hospital personnel at the prince of wales hospital, where hong kong's major outbreak began on march . concern heightened in late march when a major outbreak of sars erupted in amoy gardens, a high-rise housing estate. actually, even before the prince of wales hospital breakout on march , malik was actively looking at the possibility of the villain of the piece being a coronavirus among other possibilities. in an email on that day to a colleague in the united kingdom, he asked for information on "coronavirus control material to be used in molecular detection assays." disappointingly, the colleague knew no one in the u.k. who was actively working on coronaviruses. very from a sars patient. the chinese university of hong kong also found paramyxovirus-like particles in respiratory samples. china was not part of the network but on march , who received a letter from china's ministry of health announcing that chlamydia was found by electron microscopy in five sars patients. actually, as early as february , the ministry of health had said to the who: "it is almost ascertained that the causal agent for the atypical pneumonia outbreak in guangdong is chlamydia." this was based on the work of hong tao, a senior microbiologist at china's center for disease control and prevention. he had announced that the causative agent was chlamydia and, because of his standing, the ministry of health accepted his finding and maintained that the causal agent for sars had already been identified. the microbiology department at hong kong university had had a head start, with specimens brought back to hong kong at the risk of their lives by guan yi and b.j. zheng. but after attempting to culture about specimens, it was still unable to identify the virus involved. of course, there was no guarantee that any of the specimens brought back from guangzhou contained the pathogen in question. where the index patient dr. liu was concerned, no bacteria, virus, fungus or parasite could be found in his respiratory secretions, blood or other body fluids. as k.y. yuen acknowledged, "basically we failed to save him and also failed to make a microbiological diagnosis." but the infection of dr. liu's brother-in-law presented another opportunity. here was a patient who was suffering from exactly the same disease. the researchers wanted lung tissue from the new patient, which, they acknowledged, was an extremely invasive surgical procedure to perform on a sick patient. but after consideration by dr. andrew wong, chief of service in medicine at kwong wah, the operation was performed and the lung tissue sent to queen mary hospital for microbiological analysis. this time, at least, the microbiological team knew for sure that the specimen had come from a patient with the mystery disease. with the failure of previous attempts, almost all the team members realized that there was now a need to try other cell lines. as k.y. yuen wrote in a joint article with malik peiris: "our colleague, dr. chan kwok-hung was encouraged to try as many new cells lines (animal cells as medium for viral culture) as possible, beyond the standard four or five that were normally used. what we needed next were luck and lots of patience." sars: how a global epidemic was stopped," . abraham, twenty-first century plague, - . yuen and peiris, "facing the unknowns of sars in hong kong." . ibid. ibid, . dr. chan decided to use a cell line of fetal kidney cells from rhesus monkeys. it was rarely used except to grow hepatitis a virus but it had also proved useful in growing a range of respiratory viruses. this was done on march . two days later, there was a visible reaction as the cells appeared to be dying, that is to say, there was a virus taking over. this was confirmed through multiple tests that eliminated the possibility of contamination. "the use of this cell line (frhk- ) was probably the most important decision in the discovery of the pathogen behind sars," yuen and peiris wrote. "the lung tissue of mr. chan yp (the brother--in-law of the index patient) was inoculated into this cell line for viral culture together with other specimens from patients with pneumonia associated with recent travel to guangdong. miraculously, significant changes were observed in this cell line." but was the virus that was killing the cells the sars virus, that is, was it the cause of the disease, or did it just happen to be present? to determine this, the hong kong university team tested their virus against blood serum samples from patients at different stages of the disease, from early onset to the late stages. the test results confirmed their suspicions. as peiris said, "we had the virus growing well, it was reacting in the expected way to early and late serum samples. we were quite sure this was the virus causing sars." by march , peiris was ready to share his findings with researchers around the world. that day, he had missed the daily conference call linking sars researchers globally. but, in an email late that night, peiris indicated that hong kong university had isolated an agent from two patients with sars. the agent was isolated in continuous rhesus monkey kidney cells. it had a cytopathogenic effect, that is to say, it caused structural changes in host cells, which indicated the growth of a virus. "in conclusion," malik wrote, "we are confident that the agent in the cell cultures are associated with the sars syndrome. the identification of this agent is under way." klaus stöhr of the who subsequently published a paper on the "multicenter collaboration to investigate the cause of severe acute respiratory syndrome" in which he recalled malik peiris' report on the agent that had been cultured in rhesus monkey kidney cells. "in addition, in an immunofluorescence assay of virus-infected cells, done in a blinded trial, sera from sars patients had rising antibody titres to the new virus isolate," he wrote. "by contrast, sera from blood donors taken long before the disease emerged in hong kong had no antibody to this virus. furthermore, virus-like particles in the cytoplasm and at the cell membrance were seen in thin electron microscopic sections from infected cells." stohr concluded: "these findings proved to be the turning point in the search for the sars causative agent. the day after he informed the who network of researchers, malik peiris held a press conference in hong kong and reported that the university had identified a virus associated with sars but that his team did not yet know what kind of virus they were dealing with. "what we have here is a new, i think it is quite a tricky disease and a tricky virus," peiris said. "it is quite important for us to study this in detail before we can come to a conclusion." the south china morning post headline proclaimed: "genetists link 'tricky virus' to pneumonia outbreak." four days later, peiris held another press conference and identified the virus as a coronavirus, so called because of the crown-like spikes on its surface. the hong kong university virologist said that his team had completed the genetic sequencing of the virus, isolated from hong kong patients. "it is not one of the two known human coronaviruses and not even any animal coronavirus," professor peiris said. "we are dealing with a type of virus which we have never come across before" ( fig. . ) . the hong kong university discovery was the culmination of a worldwide race to uncover the agent that causes sars. scientists all over the world had been working around the clock and those at the university of hong kong had succeeded at being the first to identity the elusive culprit. this was a real triumph, subsequently confirmed by the who. the centers for diseases control and prevention in the u.s. also announced the discovery of a coronavirus without mentioning hong kong's breakthrough, apparently unaware that it had occurred. it issued a press release announcing that "a previously unrecognized virus from the coronavirus family is the leading hypothesis for the cause of severe acute respiratory syndrome." however, the who took it upon itself to set the record straight. dr. david heymann, who's executive director for communicable diseases, said at a press briefing: "just so you're clear. the virus was first found in hong kong, first identified in hong kong. and then it was identified at cdc. and now it's been identified by all the other laboratories." also, just as hong kong university publicized its breakthrough before the cdc's announcement, so the university was able to get its scientific discovery into print first, with the publication of a paper in the online lancet on april , , "coronavirus as a possible cause of severe acute respiratory syndrome." the success was very much the result of a group effort, as the list of authors shows, with malik peiris as the lead writer, k.y. yuen as the last writer and others, including guan yi, leo poon, john nicholls and k.h. chan, in between. in the same issue, lancet published a commentary that said: "in today's lancet, joseph peiris and colleagues provide strong evidence that sars is associated with a novel coronavirus that has not been previously identified in human beings or animals, and begin the process of eliminating the many unknowns from this new syndrome. … one of the strengths of their report, and an important means of establishing causality, is their analysis of specimens from control patients. none of the respiratory secretions from patients with other respiratory diseases contained the coronavirus rna, and none of serum samples from blood donors had serum antibody to this new coronavirus. these findings significantly strengthen the tentative aetiological association reported by other investigators from the centers for disease control and prevention in atlanta and from toronto, who have also isolated a novel coronavirus from patients with sars." two days later, the cdc article appeared in the online edition of the new england journal of medicine, "a novel coronavirus associated with severe acute respiratory syndrome." the university's lead over the cdc, with incomparably greater resources, was clear. paradoxically, it emerged later that chinese scientists on the mainland may well have been the first to identify the sars coronavirus. this apparently happened in mid-march, , even before the world health organization had issued a global alert. scientists with the chinese academy of military medical sciences had discovered a new virus in samples from patients in guangdong province. "the virus, they had noticed, had a distinctive halo of spikes that put it in a family not known to kill humans: the coronaviruses," the magazine science reported in july , by which time the world health organization had declared all countries sars-free. "by the first week of march, the group had tentative evidence that the new virus might indeed be linked to the epidemic." the problem, as is frequently the case in china, was politics. since the highly respected senior microbiologist hong tao had made the pronouncement in february that chlamydia was responsible for the mystery ailment, the ministry of health had accepted this view and the official chinese establishment would accept no other view. so the academy's microbiologists kept their mouths firmly shut. "these scientists were the first ever to see the sars virus," klaus stohr of the who said after visiting the academy, "and we had no idea." just like the outbreak in guangdong, when chinese patients and medical workers lacked information because of the communist party's penchant for secrecy, china was a victim of its own policies, this time of obstinately sticking to a position just because someone in a position of authority had made a pronouncement. the discovery of the sars coronavirus was a huge step forward in the war against the deadly disease, but by no means did it mark the end of the war. in fact, things were to get much worse before they got better. the hong kong director of health made sars a statutorily notifiable disease by revising the quarantine and prevention of disease ordinance so as to provide the legal basis for mandating close contacts of sars patients to report daily to one of four medical centers. all secondary and primary schools and preschools were temporarily suspended. the rolling stones canceled their concert, scheduled for march and . on april , the world health organization issued the most stringent travel advisory in its -year history. it recommended that "persons travelling to hong kong and guangdong province consider postponing all but essential travel until further notice." once the sars virus was grown in the laboratory and identified, it became possible to decode its genome and identify its genetic makeup. it also was possible to identify it in the body. tests could be carried out to see what effect potential treatments had. for example, in response to demand for an antiviral cure for sars, various drugs were tested. in one test, the clinical response of patients with sars to a combination of lopinavir/ritonavir and ribavirin was examined and compared with patients treated with ribavirin only who served as historical controls. the treatment was found to be significantly more effective than that provided in the historical control group. just about this time, hong kong received a rare visit from a chinese leader. premier wen jiabao visited the city in mid- , the first national leader to do so since the devastation of sars. the premier went to the university of hong kong and praised its role in the battle against the killer disease. the premier met the key figures involved, the head of microbiology professor k.y. yuen, the chief of virology professor malik peiris, and virologist at the department of microbiology, dr. guan yi. the premier was briefed by professor yuen on how, despite limited resources, the university was able to track down the agent of sars while dr. guan explained how animal viruses were discovered. within weeks of the discovery of the sars coronavirus, the viral genome had been completely sequenced, with hong kong university coming third in that race, following researchers in canada and the united states. the sequencing showed a virus that had begun life in an animal before it mutated and began to infect people. animal-or animals-carried the virus that mutated and was able to infect people? in order to prevent a recurrence of sars, it was important that an answer be found to this question. in the case of avian flu, chickens and ducks were the culprits. were domestic animals also responsible for sars? professor zhong nanshan had reported that one of the earliest sars cases in heyuan was a chef who had come into regular contact with several types of live caged animals used as exotic game food. because of this, guan yi and b.j. zheng, who led the effort to identify the animal host of the sars virus, focused their attention on wild animals recently captured and marketed for culinary purposes. while malik peiris and his people were toiling in their labs, guan yi was busy testing animals being sold in wet markets in guangdong to see what viruses they harbored. on may , , the results of a joint study by research teams in hong kong and shenzhen of wild animals taken from a market in southern china were released. the study detected coronaviruses closely related genetically to the sars coronavirus in two of the animal species tested-the masked palm civet and the raccoon dog. the study also found that a chinese ferret badger elicited antibodies against the sars-cov. the study provided for the first time an indication that the sars virus exists outside a human host. "sequencing of viruses isolated from these animals demonstrated that, with the exception of a small additional sequence, the viruses are identical with the human sars virus," it said. "information on the potential role of animals in the transmission of sars is important to overall understanding of sars. at present, no evidence exists to suggest that these wild animal species play a significant role in the epidemiology of sars outbreaks. however, it cannot be ruled out that these animals might have been a source of human infection." the wild animals sold at markets are traditionally considered delicacies and are available throughout southern china, the study reported. largely because of the findings of this joint study, conducted with the shenzhen centers for disease control, the guangdong government temporarily banned the sale of civet cats and closed down wildlife markets. but the ban was lifted a few months later after another mainland team challenged the findings and after the war on sars was believed to have been won. nevertheless, guan yi and b.j. zheng persevered, conducting further researches in guangdong's live-animal retail markets. "animals were held, one per cage, in small wire cages," they reported about one shenzhen market. "the animals sampled included seven wild, and one domestic, animal species. they originated from different regions of southern china and had been kept in separate storehouses before arrival to the market. the animals remained in the markets for a variable period of time, and each stall holder had only a few animals of a given species. animals from different stalls within the market were sampled. nasal and fecal samples were collected with swabs and stored in medium with bovine serum albumin and antibiotics. where possible, blood samples were collected for serology." sampling was carried out in shenzhen from the end of october and in guangzhou from early december . altogether, wild animals were sampled between october and january by guan and his team. of these, were positive for sars-cov-like virus, with palm civets found to be the most often infected. they discovered that "the recent sars-cov sequences from wild animal specimens collected from southern china from october to january are much more like the human sars-cov sequences from may . this indicates that the sars covs present in wild animals in southern china are heterogeneous, are continuing to evolve, and have also acquired mutations making them potentially infectious for humans." as it turned out, because of guan yi's efforts, not only was an animal link to the sars virus uncovered but another sars outbreak in guangdong was narrowly averted. on december , , a suspected human case of sars was reported in guangzhou and the patient was quarantined. the center of disease control and prevention of guangdong confirmed the case as sars. the viral genomic sequence from this new sars case was almost identical to that from palm civets, suggesting that the human patient might have acquired the infection from palm civets or other wild animals in the wet markets in guangdong. so great was the danger of another sars outbreak in guangdong among the human population that guan yi decided to appeal directly to the powers that be. as the year began, he sat down and wrote a letter to china's hong kong and macau affairs office, copies of which were also sent to the ministry of health and china's centers for disease control. "with winter coming, the wildlife markets have reopened, providing the perfect conditions for another outbreak of sars," he wrote. he listed his findings on the civet cat as a major carrier of the sars coronavirus, as well as the fact that other wild animals, too, carry the virus. he enclosed four pages of genetic sequences taken from civets. the letter was hand delivered on january . the very next day, he was invited to guangzhou to make his case in front of the most eminent scientists in the province, including professor zhong nanshan, and clinicians who had treated patients during the sars outbreak the previous year. while they were speaking, the amino-acid sequences of the human patient recover- ing from sars in a guangzhou hospital were sent to hong kong for sequencing. in an hour, the results were in: the sars patient's virus sequences were almost identical to that of the virus sequences of the palm civets. that is to say, the virus in the wild animal markets had somehow infected a human. the group decided then and there to contact the provincial governor and recommend a cull of all civet cats. professor zhong telephoned governor huang huahua recommending the slaughtering of all civet cats in the markets. the order to carry out the slaughter was given on january , , involving an estimated total of , civet cats. at a news conference in hong kong the day the order was issued, dr. zhong joined hong kong university microbiologists to announce that they had jointly completed a detailed study of sars-like viruses in civet cats together with a genetic analysis of viral samples taken from a -year-old man in guangzhou who was suspected to have sars. k.y. yuen said that while research the previous spring had shown that the sars virus that infected more than , people around the world was genetically very similar to a virus in civet cats, new research shows that the virus in civet cats "has mutated to form a new 'sublineage' of the virus." he said that a genetic sequencing of samples from the infected man in guangzhou had found that the main "spike" of protein was exactly identical, down to the last amino acid, to the new sublineage of the virus found in civet cats. professor zhong warned that civet cat feces could dry up and become windblown dust that would raise a risk of airborne infection. he said the feces carry extremely high concentrations of the virus, which can still be detected even when the feces are diluted as much as one billion times. professor yuen's conviction of the role of civet cats in the transmission of the sars virus to humans was reflected in testimony he gave in early january to the legislative council select committee set up to inquire into the handling of the severe acute respiratory syndrome outbreak by the government and the hospital authority. at one point, legislator chan kwok-keung (陳國強) asked about the origin of the virus and this exchange took place: legislator: "professor yuen, i want to ask, just now you said virus came from… some came from hospitals, some came from the community. in reality, did the virus originate from the community or from hospitals?" professor yuen: "this virus? if your question is how did the thing get here, you would never get an answer. by way of example, we currently believe that the most important source is civet cats, but in reality we cannot be % certain unless in the same second, we can give all animals in the world a one-off examination. then, we can be very certain. based on the evidence we have at the moment it mainly started from wild animals." the guangdong culling operation of civet cats began on january and the last case of sars appeared on january . after that, no new cases of sars emerged, despite the chinese new year which, as usual, saw large numbers of people traveling as they returned home for the holidays. thus, the january cull in guangdong, like that of december in hong kong, must be deemed a success in averting a pandemic. however, farmers of civet cats suffered economic disaster. researchers found that civets on farms were largely free from the virus, though those in overcrowded retail markets, where civets are put in close proximity with other species, are often infected. this raised the question whether the civet cat was the main conduit for sars or whether it was infected by another animal, which was the real reservoir of the virus. professor yuen decided to turn his attention to other animal species in the wilderness that may be carriers of similar viruses. not everyone was as enthusiastic as yuen in his efforts to gather evidence that might in effect exonerate the civet cat, after so much publicity had gone into slaughtering civet cats in guangdong. but yuen persevered, doing his research in hong kong, screening for coronaviruses in wild animals within the territory. in this he was successful. he found that the chinese horseshoe bat was the natural reservoir of sars coronavirus-like viruses. so the bats might well have infected civet cats, possibly via yet a third animal. the public health implication was that animals, such as bats, should not be mixed together with other species in wildlife markets, as was the case before . the microbiology department did not stop there. it went on to sample animals for novel viruses and, by , had identified novel animal viruses. most of them were named after hong kong or after hong kong university, such as the bat coronavirus hku found in lesser bamboo bat and the bat coronavirus hku found in the japanese pipistrellus bat. not much notice was taken of these novel viruses but, after the emergence of middle east respiratory syndrome, both were mentioned in a paper about a man who died in saudi arabia. "a previously unknown coronavirus was isolated from the sputum of a -year-old man who presented with acute pneumonia and subsequent renal failure with fatal outcome in saudi arabia," began an article in the new england journal of medicine in . "the virus (called hcov-emc, later mers-cov) replicated readily in cell culture, producing cytopathic effects of rounding, detachment, and syncytium formation. the virus represents a novel betacoronavirus species. the closest known relatives are bat coronaviruses hku and hku ." thus, hong kong university identified novel animal coronaviruses prior to the emergence of this highly fatal infection in the middle east and subsequently korea. hong kong paid a high price for sars, with more than , people laid low by the disease, with deaths. in , the government awarded professor yuen a silver bauhinia star for his discovery of the coronavirus that causes sars. professor yuen modestly said the award was recognition for all members of his team. "the award has helped boost the morale of my team," he said. "my colleagues, including malik peiris and guan yi, put a great deal of effort into tracing the source of the sars virus to civet cats. there are many more people who have made a lot of contribution." the university gave all three men-professor yuen, professor peiris and dr. guan-the special research achievement award in recognition of the team's groundbreaking discovery of the coronavirus responsible for the ourbreak of sars. one interesting achievement of his team, professor yuen said, was that at one stage it collected the highest number of flu strains in the world; but, he added with his customary modesty, by now "the beijing and the harbin group should have superseded us already." quite aptly, members of the entire team of scientists were called "heroes of the sars wars" by bloomberg. "asia also has the global scientific community to thank for quickly mobilizing to understand the mysterious new virus," bloomberg his identification of the chinese horseshoe bat as the natural host for the virus (fig. . ) . malik peiris, too, received a wealth of awards. reflecting his international outreach, the honors bestowed on him came from overseas, including the united kingdom, where in he was elected a fellow of the royal society of london, the highest scientific honor in the commonwealth. the following year, he was awarded the chevalier de la legion d'honneur by france as well as the mahathir science award by malaysia for the role he played in the discovery of the aetiological agent of sars. recognition from the hong kong government came in when he received the silver bauhinia star for "outstanding achievements in the field of virology and pathology, in particular his contribution to the prevention and control of infectious diseases." today, all three men are listed among the world's most frequently cited researchers in the field of microbiology. that is to say, they are among the top % of researchers in their field internationally. in , thomson reuters listed professors yuen, peiris, guan and poon among the "world's most influential scientific minds" (fig. . ) . so the microbiologists achieved recognition both within the university and from society at large, in hong kong and internationally. "in , we only had or people," k.y. yuen recalled. "now, microbiology has over a hundred people." at the same time, the school of public health has well over staff. "so," yuen said, "you can see the power of money. as a result, we can do much more research, and we have much better output." without the title of state key laboratory, yuen said, they would never have received this money. the people working on microbiology today include both those in the department itself and in the public health school. while both the department and the school do virology and pathogenesis, the department works more on clinical diagnosis and treatment while the school focuses more on epidemiology. they share the teaching load for medical students. k.y. yuen was promoted to chair professor in , malik peiris moved up from senior lecturer to become professor and, after sars, to chair professor. guan yi has risen from a research assistant professor when he first joined the university to professor to co-director of the state key laboratory of emerging infectious diseases and professor of virology. in january , he was promoted to chair professor. such growth in personnel, plus internal promotions, would not have been possible without greatly increased funding. the designation of state key laboratory in mainland china would ordinarily come with substantial funding but, because the university is in hong kong, it cannot directly receive such funds from beijing. from , when the title was granted, until , it could only apply for limited funding within the mainland, which had to be spent on collaborative projects with mainland researchers. however, beginning in , the hong kong government started to provide funding to the state key laboratory through what is now its innovation and technology bureau, to the tune of $ million a year. this was a highly appreciated windfall and, with this additional funding, the department has grown much faster in recent years. the physical laboratory at the university has also been upgraded. laboratories are graded by biosafety levels, measuring the biocontainment precautions required to isolate dangerous biological agents in an enclosed facility, ranging from to . at the time of sars, the laboratory was at a biosafety level of p + and, in , it was upgraded to a p . yuen thinks it may never become a p -the kind of lab where all the researchers wear astronaut suits because they are working on something very dangerous, like ebola. in the aftermath of such traumatic events as the h n outbreak of , followed by sars six years later, hong kong learned that vigilance was vital. the government was determined that whenever the next health challenge arose, it wouldn't be unprepared. in june , hong kong set up the center for health protection (chp), using the centers for disease control and prevention in the united states as a model. creation of the center was recommended by the sars expert committee appointed by chief executive tung chee-hwa. the government also earmarked a one-off grant of $ million to support research into emerging infectious diseases. while $ million was to support infectious disease research in the mainland, the bulk, that is, $ million, was directed to support local investigator-initiated research and commissioned projects through the creation of the research fund for the control of infectious diseases. the aim of the fund was to encourage, facilitate and support research on the prevention, treatment and control of infectious diseases. this was superseded in with the creation of the health and medical research fund, with the injection of an additional $ billion. on a down-to-earth level, the government took steps to ward off or at least mitigate the return of avian flu. retail markets for live poultry came under close supervision. rest days were introduced during which retail markets for live poultry were closed and thoroughly cleaned. tests showed that viruses were dramatically reduced after a rest day. live chickens were no longer imported from mainland china. those taken to market came from local farms, and any chickens not sold at the end of the day were not returned to the farms but slaughtered, so that viruses could not be introduced-or reintroduced-onto farms from retail markets. the university of hong kong, too, responded to the new situation. in , it approved a proposal to establish a school of public health, which was formally inaugurated in . the university was invited to submit proposals for research related to basic laboratory, epidemiological and public health research in emerging infectious diseases. the university was asked to participate because of its pioneering work in discovering the sars-coronavirus, its outstanding work on avian influenza a (h n ) research and surveillance, and its track record of peer-reviewed publications, especially in journals with high impact factors. the university submitted a proposal, "research preparedness for emerging and potentially reemerging infectious diseases in hong kong." as a result, $ million was approved for it to undertake a five-year portfolio of basic laboratory, epidemiology and public health research, as well as upgrade its bio-safety level laboratory with enhancement for animal experimentation. it was just as well that hong kong was consolidating its infectious disease and virology expertise and facilities after sars because another storm was brewing. in march , there was an outbreak of "flu" in a town called la gloria in veracruz, mexico. it affected % of the town's population and killed three children. it was believed to be the "common flu." between th and th april, specimens collected from two children with flu in california, u.s.a., were shown to have a strain of "swine flu" called h n . on april , the world health organization issued a disease outbreak notice confirming the infection of a number of people in mexico and the united states by swine influenza a (h n ) viruses not previously detected in pigs or humans. the th was a friday and malik heard the news friday night. he gathered the "flu team" for a meeting the next day when they discussed what steps to take. a priority was to set up diagnostic tests for detecting the virus when it arrived in hong kong, as it inevitably would. they had the sequence of the virus provided by the u.s. cdc but for such molecular detection tests a positive control virus is needed to establish that the test is working properly. the new pandemic h n virus was not available in hong kong. but a decade-long surveillance of swine influenza viruses provided a source within which to search and, indeed, a virus close enough to serve as the positive control was found. the next question was to understand the origins of the virus. it was decided to start genetic sequencing of the many hundreds of swine influenza viruses available from this surveillance effort. by april , jose angel cordova, the minister of health for mexico, was reporting that , cases had been detected, people had died and an additional were in hospital. these were alarming statistics. on april , the u.s. declared a public health emergency and, the following day, the world health organization raised its pandemic alert to level , with being the highest. on may , hong kong confirmed its first case of swine flu: a mexican national who had arrived via shanghai and stayed at the metropark hotel. it was the first reported case in asia, and the hong kong government responded with the seriousness that it warranted. the alertness level was raised to "emergency." with the example of dr. liu jianlun-the guangdong doctor who stayed overnight in the metropole hotel and infected more than a dozen other guests and visitors-seared into its collective memory, hong kong was not going to take any chances. while the -year-old mexican patient was treated in isolation in hospital, the metropark hotel was quarantined and its roughly guests kept in confinement for a week despite their protestations. other interventionst measures learned during sars included the closure of schools-primary schools, kindergartens and special schools, initially for two weeks and then extended to the summer holidays. historically speaking, hong kong had been identified with influenza research for decades. the pandemic, after all, was named hong kong flu after having first been identified in the city. then the bird flu saga of and sars in put hong kong on the front lines of emerging disease outbreaks. "as a result, hong kong has invested heavily in infrastructure in preparation for future epidemics and pandemics," explained one paper commenting on the territory's public health research response to the outbreak. "there has also been substantial investment in research infrastructure, essential to guide evidence-based policy locally as well as internationally." thus prepared, even before the first case was reported in hong kong, it operated under containment efforts, including entry screening at airports, ports and border crossings, hospital isolation of cases, tracing and quarantine of contacts, and routine antiviral prophylaxis. on april, hong kong raised its alertness level from "alert" to "serious," just one step away from "emergency." the next day, the world health organization, too, raised its alertness level. dr. keiji fukuda, who's assistant director-general, explained that the increase in pandemic alert level was in response to the outbreak of swine flu that had originated in mexico, but that it did not mean that a pandemic was "inevitable." hong kong also made swine flu a notifiable disease, a step it learned from its sars experience. "actually, we had a number of research grants for pandemic preparedness," recalls professor benjamin j. cowling, head of epidemiology biostatics in the school of public health. "this allowed us to scale up for research into the pandemic, so when the pandemic actually came here, we did a number of studies which were the envy of most other places in the world" (fig. . ) . a crucial question was how effective were these various measures at warding off the arrival of swine flu, verifying its severity and preventing or deterring its spread? entry screening, cowling and his colleagues determined, could delay local transmission for one to two weeks. "a delay of one to two weeks could be useful if the additional time permits more comprehensive planning and preparation for a local pandemic, or shortens the time required for other pandemic mitigation measures such as schools closures to be sustained," they wrote. "however, the benefits of local screening should be balanced against the considerable resources required to implement screening." still, when the virus reached hong kong, it spread rapidly. within five months, % of children in hong kong were infected. fortunately, it was not as severe as initially feared but the speed with which it spread was astounding. if it had been really virulent, there could have been a global catastrophe. while the disease emerged first in north america, by may , it had spread to countries, causing the world health organization to raise its pandemic alert to level of . hong kong knew that it would not be spared. only the previous year, the government had created the post of under secretary for food and health, with professor gabriel leung as the first occupant of the post. when h n emerged, he mobilized his former colleagues at the university to respond (fig. . ) . in the u.s., the situation was worsening. a health alert was issued to doctors, who were warned of a new strain of swine flu that was a combination of swine, avian and human influenza that had not been seen before. the national broadcasting corporation (nbc), seeking expert views on the situation, was able to contact professor guan yi, who was at that time in india, helping to set up a poultry influenza surveillance network. he was at the bombay airport when nbc managed to reach him to ask for urgent comment on the spread of swine flu to humans. guan yi's immediate response was that it was not easy to detect this kind of virus. after all, the h n virus was already in humans, as a human virus. guan yi went to work immediately after returning to hong kong. he told his team, "we need to find out how this virus was generated and where the virus came from." they had an advantage in that hong kong was probably the only place in the world where there had been close surveillance and sampling of swine for over a decade as part of its anti-influenza program. guan yi, who had written his doctoral thesis on swine flu, had accumulated data on the subject while a student in the s under ken shortridge, who himself had data going back to the s. so while the rest of the world was short on information regarding swine, hong kong was data rich. guan yi and his associates set to work on the unique data available to them. according to guan, the bulk of the analysis was done in one intensive week of work, from april to may . with help from andrew rambaut, an evolution scientist with the institute of evolutionary biology at the university of edinburgh, they were able to "understand the evolutionary pathway of this virus." "here we use evolutionary analysis to estimate the timescale of the origins and the early development of the s-oiv epidemic," the paper explains. "we show that it was derived from several viruses circulating in swine, and that the initial transmission to humans occurred several months before recognition of the outbreak." while surveillance and sampling had been taking place in asia, this was not true of north america, and as a result there was "a long period of unsampled ancestry before the s-oiv outbreak, suggesting that the reassortment of swine lineages may have occurred years before emergence in humans." furthermore, it said, "the unsampled history of the epidemic means that the nature and location of the genetically closest swine viruses reveal little about the immediate origin of the epidemic…. our results highlight the need for systematic surveillance of influenza in swine, and provide evidence that the mixing of new genetic elements in swine can result in the emergence of viruses with pandemic potential in humans." the paper was submitted to the journal nature for publication on may ; it was accepted june and was published online june . the timing was fortuitous. june was the day when dr. margaret chan, director-general of the world health organization, announced the raising of the level of influenza pandemic alert from phase to phase , the highest level. "the world is now at the start of the influenza pandemic," she declared somberly. this means that on may , when the paper was submitted, "even before the world knew what was happening"-in the words of guan yi-"i provided critical information to the world with the university of hong kong catching the attention of the world." the university's virologists were keen to study this novel virus, which was spread not by birds but by pigs. a study of the lineage of the h n / viruses showed that three major lineages of swine h influenza viruses had been prevalent in pigs in surveys conducted in hong kong over the past years. the h n flu virus was a triple reassortant, combining the classical swine h n , the european "avian-like" h n and triple-reassortant h n (trig) viruses. and while the virus had jumped from pigs into humans, actually this had happened more than once. "after circulating in humans for some time they jumped back to pigs and tried to reassort with other pig virus," reported professor leo poon, a diagnostic expert in identifying viruses. "that was quite interesting because it highlights the pig as a major reservoir, or intermediate host." a paper published in the prestigious science journal, co-authored by leo poon, guan yi, malik peiris and others concluded: "the pandemic, although mild and apparently contained at present, could undergo further reassortment in swine and gain virulence. it is therefore important that surveillance in swine is greatly heightened and that all eight gene segments are genetically characterized so that such reassortment events are rapidly identified." observations made over years of pigs in a hong kong abattoir were able to show that all major lineages of swine viruses of north american or european origin were present in chinese pigs from different provinces shipped to hong kong for slaughter. although pigs, unlike birds, don't fly, they are exported from one country to another, often for breeding purposes. so, although the epidemic did not emerge in china but in mexico, analysis of pigs in china was able to show how the mixing of viruses was occurring. peiris and his colleagues argued that similar events probably had also occurred, undetected, in mexico. indeed, they were right, but it took another years to find these viruses in mexico. so great was hong kong's input that, in - , it contributed half of all the known swine influenza genetic data in the world. the diversity of genetic variants found in the studies by the hong kong group also allowed them to understand the genetic determinants that allowed a human transmissible virus to emerge from these precursor swine viruses. according to cowling, when there is a new influenza virus, the three immediate priorities of public health officials are to determine, first, how quickly it spreads between people, how severe the infections are, and what the options are for controlling it, that is, what can be done and the potential for success of such efforts. "the research that we did here covered all three of those important areas," he said, whereas other research groups or government ministries are usually unable to do that. another project that cowling and his team did was a comparison of the h n virus and seasonal influenza viruses in community settings. fortuitously, cowling was in the midst of doing household transmission studies when h n struck. he identified patients with flu in the clinics of general practitioners, then requested permission to test members of the household. when the epidemic arrived, he continued this work. the information that he was able to gather turned into a very important paper. for one thing, there is very little research data on the comparative epidemiology and virology of the pandemic influenza a (h n ) virus and co-circulating seasonal influenza a viruses in community settings. cowling and his team recruited index patients with acute respiratory illness from outpatient clinics in hong kong in july and august . they then followed household members of patients who tested positive for influenza a virus on rapid diagnostic testing and collected nasal and throat swabs from all household members at three home visits within days for testing. they were able to conclude that pandemic h n virus has characteristics that are broadly similar to those of seasonal influenza a viruses in terms of rates of viral shedding, clinical illness and transmissibility in the household setting. "the household transmission studies allowed detailed inferences on the transmissibility of ph n as well as the (mild) clinical profile of cases in the community," a review of hong kong's public health research response to the pandemic concluded. "household studies have the unique advantage of a natural setting that allows comparisons of transmission characteristics and the effects of host, viral, and environmental factors on transmission." one study by cowling and his team was to establish the transmissibility and virulence of the pandemic strain, information that was a priority for national and international health authorities in . patient data on all laboratory-confirmed pandemic h n cases reported between may and november , were collected by the hospital authority and the center for health protection. during that period, h n infection was a reportable disease, so the data collected was likely to be comprehensive. the information included demographic date on age and sex, clinical information including illness-onset date, laboratory-confirmation date and hospital-admission date. the researchers found that the estimated reproduction number of pandemic h n appeared to be lower in hong kong than in other countries. the hospital admission rate in hong kong was high due to broader admission criteria, "with young children and pregnant women routinely admitted for testing and investigation." while the overall number of severe hospital cases was not high, professor k.y. yuen found that for severe cases, the viral load in the respiratory tract didn't decrease rapidly despite oseltamivir treatment. this led him and his associates to try another method: they selected mildly infected patients with a high level of neu-tralizing antibody and used the convalescent plasma of these patients to treat those severely ill. yuen found that the treatment of severe a influenza (h n ) within days of symptom onset was associated with a lower viral load and reduced mortality. the mortality in severely ill patients treated by convalescent plasma was % whereas those treated by tamiflu alone was . %. dr. joseph t. wu of the school of public health led a study on the infection attack rate and the infection-hospitalization probability from data provided daily by the hospital authority and the department of health, from which he could construct an epidemic curve describing how fast the disease was spreading in hong kong. "the hospital authority gave us the number of confirmed infections and hospitalizations each day," dr. wu explained, "and so data can easily be obtained on the severity of the h n infections." wu also approached research on the infection attack rate and severity from a different angle. working together with the hong kong red cross, researchers tested , blood samples from blood donors during the period when the virus was active. they discovered that almost half of all schoolage children in hong kong were infected during the first wave. however, because the symptoms were mild, few of them went to hospital. paradoxically, a much smaller percentage of older adults aged - years were infected, but a much higher percentage went to hospital. if it wasn't for the serological tests, such a phenomenon may have gone undetected and the disease may have been thought to be one that primarily attacked older people. wu and his team also measured the impact of school closures on the mitigation of the h n pandemic. they concluded that the closure of secondary schools for the summer vacation "was associated with substantially lower transmission across age groups," and estimated that reporting of cases "declined to . % of its initial rate through the second half of june." by comparison, attack rates in previous epidemics have generally been highest in younger children, and this was true in mexico and chicago. this finding, they reported, "intuitively implies that closures were effective in preventing infections in this age group" ( fig. . ). the data generated by the university was shared with the government and the who, giving them real-time situation awareness of the pandemic, even before the relevant papers were published. so impressive was hong kong's performance that at the second global influenza seroepidemiology expert meeting sponsored by the european center for disease prevention and control in in stockholm, the chairman, angus nicoll, speaking on sustainability of serological surveillance, cited two options: "routine annual surveys," such as those conducted by israel, norway and poland, or "fast ad hoc quality research," a la hong kong. at one point, he said, "in the next pandemic, maybe all of us should subcontract our epidemiology work to hong kong." at the end of march , a new virus was detected in china. first, a father in shanghai became ill of severe pneumonia and died. then two sons also developed quite severe pneumonia. this was scarily reminiscent of the sars epidemic a decade previously. while they tested negative for sars, it turned out that they had influenza, but a hitherto unknown kind of flu, h n . the chinese authorities responded quickly by establishing a joint multi-sectoral coordination mechanism, initiating several investigations, notifying the world health organization, sharing viruses with who's influenza collaborating centers and other laboratories and mounting effective counter measures such as closure of live poultry markets in some locations. subsequently, who undertook a six-day joint mission to china. malik peiris was part of the mission. live bird markets were an immediate suspect. even though some people refused to believe that the virus came from chickens, shanghai closed all live bird markets and human infections disappeared. that made it quite clear that the retail poultry market was the cause. china cdc did a lot of work, but encountered opposition from those involved in the poultry trade and in agriculture. because the poultry didn't sicken, farmers weren't too concerned about whether they were infected or not. and while closing live markets was effective in combating the virus, it was also extremely costly. a joint assessment was made by experts from china and the who. "what we found is the virus is located in lots of different parts of china," recalls fukuda, who was assistant director-general for health security of the who at the time. "we also found that the risks of getting infected appeared to be similar to h n , some kind of contact with infected markets, with poultry markets. we also saw that when cities took control measures, close down markets, clean up markets, you could reduce the infection." it was, malik said, "like the h story all over again. difference is that h is even more dangerous than h because it was able to infect humans more easily and because it caused no illness in birds-that is, it was a virus able to spread silently in poultry. since , h n has continued to be present in china and, in fact, there was an upsurge in . however, according to fukuda, "we don't see major changes in the virus, or that it's more transmissible; based on what we know both in and now, it is a reflection of an increase in infection in birds and increased contact between humans and infected birds." fukuda is quick to compliment researchers in the school of public health, now his colleagues, such as "malik, guan yi and leo poon, and ben cowling." this group, he said, "has continued to operate at a very high level. the university here has such a strong research team, and they have collaborators in china." in , when swine flu was first reported, guan yi was traveling in india. on march , , when china reported to the world health organization the detection of three cases of human infection with a novel influenza a (h n ) virus, he was again traveling. but this time, he was on holiday with his family in guilin, china, the country where the outbreak was occurring. his immediate thought turned to the recent reports of thousands of dead pigs found floating in the huangpu river in shanghai, which had been dumped in the water by farmers. it crossed his mind that the dead pigs and sick humans might be connected. after returning to hong kong, guan tested samples of the virus on various animals, including pigs, and concluded that the h n virus did not kill the pigs. that was one less thing to worry about. but the main concern was the infectivity and transmissibility of this new virus. a group of scholars from the university of hong kong and from shantou university, plus international and mainland chinese experts, published an article in science magazine. these scholars conducted experiments on ferrets, which are considered the primary mammalian model for human influenza. while healthy ferrets inoculated with the virus displayed a brief fever one or two days after inoculation, with "robust sneezing and nasal discharge," and three ferrets placed in direct contact with the inoculated group displayed similar symptoms, only one of three airborne-exposed ferrets displayed such symptoms, suggesting that transmission by air was much less efficient. though the paper was formally published july , it was submitted april , accepted may and published online may . "we were," guan yi said, "the first team in the whole world to publish such a paper to define virus infectivity and transmissibility." another paper in the lancet showed that h n was much more efficient at infecting the human bronchus than h n so that the chance of getting infected and potentially transmitting it to others was higher. still, the question was, where did this new virus come from? the answer, like that for h n , was poultry. "china has the largest poultry population in the world," guan yi observes. "domestic duck is the natural host of influenza virus, and % of domestic ducks in the world are in china. likewise, % of domestic geese are in china." at the time, it wasn't clear which animal was the host to the virus, so guan and his key associate huachen zhu, also known as maria, sampled all major poultry from markets. "we pinpointed chicken as the source," guan said. surprisingly, the virus was in the respiratory tract, not the digestive tract. some people, zhu and guan said, offered the pigeon as a possible suspect, because the pigeon population is relatively small and the economic impact of its obliteration would be less damaging, but they showed beyond doubt that the chicken was the culprit. while the paper did not appear until the october issue of nature-and even the online edition wasn't published until august, it was submitted on may , less than two months after the discovery of h n and at a time when china's ministry of agriculture was arguing strongly that chickens were not the source. again, a group of experts, including guan yi, was able to show how the h n virus emerged from wild bird and chicken viruses. "preliminary analyses suggest that the virus is a reassortant of h , n and h n avian influenza viruses, and carries some amino acids associated with mammalian receptor binding, raising concerns of a new pandemic," they wrote in nature, in an article submitted on may , . "however, neither the source populations of the h n outbreak lineage nor the conditions for its genesis are fully known." they went on: "here we show that h viruses probably transferred from domestic duck to chicken populations in china on at least two independent occasions. we show that the h viruses subsequently reassorted with enzootic h n viruses to generate the h n outbreak lineage." field surveillance was conducted in wenzhou, in zhejiang province, rizhao, in shandong province, and in shenzhen, in guangdong province. according to the authors, previous analyses suggested that the n gene of the h n outbreak lineage was derived from wild bird viruses in europe and korea. however, their data showed that, for this gene, more closely related h n and h n viruses were found in migratory wild birds in hong kong in - . the authors concluded: "domestic ducks seem to act as key intermediate hosts by influenza viruses from migratory birds, by facilitating the generation of different combinations of h and n or n subtype viruses, and by transmitting these viruses to chickens. after transmission, reassortment with enzootic h n viruses formed the current h n or h n viruses seen in chickens. this probably led to outbreaks in chickens, resulting in the rapid spread of the novel reassortant h n lineage through live poultry markets (lpms), which then became the source of human infections. the cessation of human infections after the closure of lpms, after a precedent set during the hong kong h n 'bird flu' incident in , strongly supports this proposition." so the virus went from wild birds to domestic ducks to chickens, before infecting humans. the authors reported the discovery of an h n virus in chickens that has the ability to infect mammals experimentally. this, they said, suggests that h viruses may pose threats beyond the current outbreak. "the continuing prevalence of h viruses in poultry could lead to the generation of highly pathogenic variants and further sporadic human infections, with a continued risk of the virus acquiring human-to-human transmissibility," they warned. another paper, produced with high input by maria zhu, appeared in june in nature again. it was on the dissemination, divergence and establishment of h n viruses in china. the authors showed that since h n was first reported in march , the virus had spread from eastern to southern china and had become persistent in chickens. moreover, repeated introduction of viruses from zhejiang to other provinces and the presence of h n viruses at live poultry markets had fueled the recurrence of human infections. "the rapid expansion of the geographical distribution and genetic diversity of the h n viruses poses a direct challenge to current disease control systems," the authors reported. "our results also suggest that h n viruses have become enzootic in china and may spread beyond the region, following the pattern previously observed with h n and h n viruses." while the article appeared in print in june , it was submitted more than eight months before, on september . papers such as the nature article marked a major advance in human knowledge of the h n virus. his group, guan said, had contributed at least % of the data on the h n influenza virus in genbank, the database produced and maintained by the national center for biotechnology information as part of the international nucleotide sequence database collaboration. it is certainly a tribute to hong kong, both to the government and to researchers in academia, that while h n is now endemic in mainland china, there has to date not been a single local case in hong kong. how was hong kong able to keep h n at bay? the answer lies in the interventions to reduce zoonotic and pandemic risks. one important step is the closure of live poultry markets. such closures stopped h n outbreaks in the mainland, but they were costly to the poultry industry. the closure of wholesale and retail markets in shanghai, hangzhou, huzhou and nanjing in is believed to have cost the poultry industry about us$ billion. but there are also steps that can be taken short of shutting down the markets, steps that had proven effective in hong kong, such as rest days, when the markets are closed for a thorough cleaning, and banning of live poultry being kept overnight in live poultry markets. separation of live ducks and geese from chickens can also reduce the risk of intermingling of different forms of viruses. one problem in countering the h n virus is that the industry has little incentive to take any steps to detect its presence since the virus doesn't sicken birds, only its human hosts. another measure taken by hong kong is a ban on holding poultry overnight in live poultry markets. this way, incoming chickens are not in the market for long enough to be newly infected and, in turn, infect other birds. other steps include the removal of fecal matter, drinking water and poultry feed because viruses survive longer in water than on surfaces. cages, too, need to be cleaned regularly and should be made of materials easily cleaned, such as plastic, not wood or bamboo. such measures, proven to work in hong kong, can usefully be adopted elsewhere, such as in mainland china or vietnam. because the scene of action of the h n virus was initially not in hong kong, the hong kong research teams established collaborations in the "hot spots" in china. k.y. yuen and his collaborator, professor honglin chen, flew to see their mainland collaborators to get clinical data from infected patients, the virus strain for full length sequencing, tissues from dead patients and, most importantly, virus strains from the wet market poultry. the first paper on h n proving the link between human cases of h n virus and poultry h n virus in the markets was published in the lancet. yuen and his team, in another paper, showed that normal blood donors don't have anti-h n antibodies whereas more than % of poultry workers were antibody positive to h n . this further confirmed the link between h n in humans and h n in poultry. a review article was published in the lancet comparing h n bird flu in hong kong in and h n in shanghai years later. crossing the species barrier from bird to human was previously unknown to medical history. the paper was called "the emergence of influenza a h n in human beings years after influenza a h n : a tale of two cities." as the authors noted, hong kong and shanghai are located along the avian migratory route at the pearl river delta and yangtze river delta. they ended with the observation: "why h n seems to be more readily transmitted from poultry to people than h n is still unclear." malik peiris and hui-ling yen went to shanghai and worked with researchers there on studying patients with h n disease. in a collaborative paper in lancet, they reported the emergence of oseltamivir resistance in some patients that was associated with treatment failure and poor clinical outcome. the h n outbreak also saw the beginning of much closer collaboration between the university of hong kong and the chinese center for disease control and prevention (china cdc). actually, the two institutions had collaborated previously, for example, on a study of hand, foot and mouth disease in china during the - period. shortly after the chinese government announced the emergence of the new h n avian flu disease, hongjie yu, director of the china cdc's division for infectious diseases, contacted dean gabriel leung on his cell phone to discuss the situation. the dean immediately flew to beijing with a group of about ten hong kong university specialists, including ben cowling and joe wu, and stayed there for about a month to take part in making an initial risk assessment on how easily the virus spread, its severity, control measures, the characteristics of the virus, and so on. after a month, the two sides published a series of papers led by gabriel leung as senior author, in which scholars from both sides participated. from to , the h n outbreaks came in annual waves, and specialists from the china cdc and hku studied each one closely. one article, published by the lancet online on june , with hongjie yu as the lead writer, was an assessment of clinical severity of human infection with avian influenza a (h n ) virus. it concluded that human infections with avian influenza a (h n ) virus "seem to be less serious than has been previously reported." it also said that "many mild cases may already have occurred," thus lowering the mortality rate even more. another article, published by lancet online the same day, had ben cowling as the lead writer. it compared the epidemiology of human infec-tions with h n and h n in china. the fatality rate on admission to hospital was % for h n and % for h n , meaning that there was a lower death rate among the older h n sufferers than for the younger victims of h n . the authors acknowledged that the difference in susceptibility to serious illness with the two different viruses remained unexplained. they also collaborated anew on hand, foot and mouth disease, writing a joint paper that provided scientific evidence to support the chinese government's policy of vaccination. a later paper was on hepatitis a and hepatitis e in china. the collaboration between hku and china cdc went so well that a memorandum for cooperation by the two sides was signed on august , , providing for such cooperation to continue for the next years. the purpose was to "improve and enhance the capacity of understanding, surveillance and control of infectious diseases in china" as well as to develop training programs for people from both sides. the two parties agreed that their collaboration would include research projects on infectious diseases; reviewing and evaluation of the infectious disease surveillance in china and seasonal influenza and avian influenza h n and h n . hongjie yu, director of china cdc's division for infectious diseases, confirmed that hku experts, such as gabriel leung, ben cowling and joseph wu, were very helpful to china cdc in the study of emerging infectious diseases with potential pandemic threat and risk assessment. he said: "we have already set up a collaborative platform in this field and definitely will be working closely together to monitor the current outbreaks of emerging infections diseases (eids) like avian influenza h n , h n etc. and to respond to future eids as well." the surgeon general of the united states, william stewart, is frequently quoted as having said in : "the time has come to close the book on infectious diseases. we have basically wiped out infections in the united states." whether he said it or not is now immaterial. the fact is that infectious diseases have not been wiped out, and the world needs to be ever alert to new threats. as for what constitutes modern outbreaks, keiji fukuda has an intriguing observation (fig. . ) . "modern outbreaks are not disease," he said. "in textbooks you read about disease. modern outbreaks are combinations of disease and anxiety, disruption; when you have something like sars, there is a huge amount of anxiety. in beijing there was a day when there was virtually no car traffic at all, the entire city was at a standstill-that was not disease. that was fear of the disease." he continued: "i think if we look back in history, in the epidemic, we can see where fear and actual disease are commensurate; - million people died around the world, like black plague in the middle ages. but with sars and bird flu, we're not talking about millions of people dying and yet we're talking about that level of fear, almost paralysis. managing the disease aspect is relatively easier than managing the fear aspect." despite books and movies about existential threats to the human species, experts are guardedly optimistic when speaking of whether future influenza pandemics are inevitable. dr. peter palese, a flu expert at the mount sinai school of medicine, points out that human flus can infect people who inhale only one to ten virus particles, but it takes , to a million particles of an h bird flu to infect a human. "that's why people who live under chickens in markets in asia get it, and we don't get it on fifth avenue," dr. palese said. more than a decade ago ken shortridge pointed out that hong kong had stopped the h n virus in its tracks three times through surveillance, surveillance, surveillance. "i have no idea if h n will cause a pandemic," he said. "we can't be certain at all." he did warn that h n was in a "smoldering phase" of evolution, similar to that undergone by the virus before the influenza pandemic broke out. but he traced the root of the problem to people, not birds, saying: "the industrialization of poultry is the nub of this problem. we have unnaturally brought to our doorstep pandemic-capable viruses. we have given them the opportunity to infect and destroy huge numbers of birds and … jump into the human race." he went on: "something is not right. human population has exploded, we are impinging on the realms of the animals more and more, taking their habitats for ourselves, forcing animals into ever more artificial environments and existences." so hong kong has a need to remain vigilant, not only for itself but for the world. besides, infectious disease expertise has undergone a major transformation in the last two decades. when bird flu struck hong kong in , the territory was dependent on external expertise to cope with that disease. over the intervening years, researchers at hong kong university have become leading global experts in their own right. the lessons of bird flu and sars have been well and truly learned. hong kong has grown and matured through those difficult days. its research-based control efforts benefit the nation and the global community. as angus nicoll has observed, hong kong does fast as well as high quality research and does excellent epidemiological work, from which the rest of the world can benefit. interview with fukuda. cdc lab analysis suggests new coronavirus may cause sars reassortment of pandemic h n / influenza a virus in swine long-term evolution and transmission dynamics of swine influenza a virus hemagglutin-neuraminidase balance confers respiratory-droplet transmissibility of the pandemic h n influenza virus in ferrets comparative epidemiology of pandemic and seasonal influenza a in households the epidemiological and public health research response to pandemic influenza a(h n ): experiences from hong kong the effective reproduction number of pandemic influenza: prospective estimation hyperimmune iv immunoglobulin treatment: a multicenter double-blind randomized controlled trial for patients with severe influenza a(h n ) infection convalescent plasma treatment reduced mortality in patients with severe pandemic influenza a (h n ) virus infection the infection attack rate and severity of pandemic h n influenza in hong kong school closure and mitigation of pandemic (h n ) , hong kong dissemination, divergence and establishment of h n influenza viruses in china interventions to reduce zoonotic and pandemic risks from avian influenza in asia effect of closure of live poultry markets on poultry-to-person transmission of avian influenza a h n virus: an ecological study human infections with the emerging avian influenza a h n virus from wet market poultry: clinical analysis and characterisation of viral genome avian-origin influenza a(h n ) infection in influenza a(h n )-affected areas of china: a serological study the emergence of influenza a h n in human beings years after influenza a h n : a tale of two cities association between adverse clinical outcome in human disease caused by novel influenza a h n virus and sustained viral shedding and emergence of antiviral resistance hand, foot, and mouth disease in china, - : an epidemiological study human infection with avian influenza a h n virus: an assessment of clinical severity comparative epidemiology of human infections with avian influenza a h n and h n viruses in china: a population-based study of laboratory-confirmed cases routine pediatric enterovirus vaccination in china: a cost-effectiveness analysis changing epidemiology of hepatitis a and hepatitis e viruses in china cooperation agreement between division of epidemiology and biostatistics, school of public health, li ka shing faculty of medicine, the university of hong kong, and division of infectious diseases, the chinese center for disease control and prevention in key: cord- - vwgg e authors: anis, mohab; altaher, ghada; sarhan, wesam; elsemary, mona title: construction and building applications date: - - journal: nanovate doi: . / - - - - _ sha: doc_id: cord_uid: vwgg e the construction industry is a particularly attractive industry for nanotechnology applications. since it employs a diversity of building materials, nanomaterials can be employed to enhance the materials’ performances, durability, longevity and sustainability. the construction and building practice is detrimental to the environment in various aspects such as electricity consumption, landfill accumulation, unhealthy aesthetics and neighborhoods. this chapter shows how nanotechnology-based building materials are playing an important role in green architectural design and construction, which has become a growing trend in many countries. nanomaterials could be integrated with cement, concrete, or windows to conserve energy, minimize electricity bills and sanitize the surrounding atmosphere. nevertheless, the industry is still facing many hurdles towards the wide application of nanomaterials in a cost effective manner. construction and building are major contributors to the rising carbon emissions and the global climate change. in addition, the construction industry is a rapidly growing industry. the nature of the construction industry involves the application and use of a diversity of building materials. this leads to nanotechnology being rapidly adopted by the construction market in several aspects like coatings, insulation materials, and building materials (steel, cement, asphalt, glass, polymers, etc.). nanomaterials are currently employed in cements, steel, and even windows to render buildings greener, more cost effective and safer. green construction has become the dominant trend in the construction industry, which means that buildings should meet certain specifications in the materials used, the processes employed, and in the behavior of the residents. these specifications aim at reducing co emissions and reducing the negative impact of the construction industry on the environment. green architectural design and construction has shifted dramatically since the evolution of nanotechnology. many people are now seeking healthy lifestyles and environmentally friendly neighborhoods. green building is currently experiencing a growing demand by governments, architects, and people, especially after many cities have adopted strict regulations regarding green construction. globally buildings consume around one third of the worldwide electricity [ ] , with cement alone contributing to the global co emissions by around % [ ]. one way nanotechnology is used in construction is the concept of nanoreinforcements which involves reinforcing the body by adding dispersions that are in the nano-size scale. for example, nanoreinforcements in steel have rendered steel stronger and lighter. nanoreinforcements in cement have rendered it more durable and cost effective. another application of nanotechnology in the market involves making ultra violet (uv) absorbing, self-cleaning, and depolluting coatings for windows. moreover, nanotechnology has been rapidly adopted in air and water purification systems. the next generation of nanotechnology applications in construction has begun to involve building integrated photovoltaics (bipv), which are solar cells that can be integrated within buildings in smart designs without affecting the buildings' aesthetics, as well as being a clean source of energy and electricity. even electronics and sensors are being developed to be integrated with buildings. smart curtains or windows are expected to change the way people are experiencing the way they live (imagine walls that change colors with just a click!) [ ] . it is important to note that there are still a lot of barriers to the adoption of nanotechnology in building, however, there are certain drivers and enablers that if emphasized and executed will overcome such barriers. nano-enhanced materials are more expensive than conventional materials. they yield high performances using small amounts of the materials. thus, it is expected that with the continuous r&d (research and development) efforts to improve nanomaterials' performances at lower costs, the construction market will continue to increasingly adopt the nanomaterials. proper education of the construction industry about the potential benefits associated with nanotechnology is the starting point towards the rapid adoption of nanotechnology in building materials. although nano-based construction materials are not economically competitive compared to conventional materials, continuous efforts are undertaken to render them cost effective. in addition, strict regulations have proved to be an important surge to the adoption of nanotech in green construction. one significant example is the us leed (leadership in energy and environmental development) which has developed strict minimum standards to simultaneously force and encourage builders to conserve energy and reduce carbon emissions. hong kong fights germs in subways. a japanese antimicrobial nanocoating that had long lasting efficiency offered maximum protection and elevated hygiene levels in hong kong subway stations. • owing to their nanosize, antimicrobial nanoparticles offered the potential to maximize public protection against germs in the highly populated hong kong subway stations. • nano silver-titanium dioxide coating (nstdc): a coating containing tiny particles of silver and titanium that are very active in killing microbes. • the nano-formula has been successfully applied by mtr (mass transit railway) in hong kong subways, and has been continuously monitored to expand its application in other facilities inside and outside hong kong. sars outbreak. in the spring of , a large outbreak of severe acute respiratory syndrome (sars) occurred in hong kong and other asian countries. the contagion rapidly spread throughout the world. its rapid transmission and high mortality rate made sars a global threat for which no efficient therapy was available and proactive empirical strategies had to be developed to treat the patients and protect healthy individuals. high risk zones. around . million commuters use hong kong railway and subway stations daily, and they are highly susceptible to dangerous microbes adhering on floors, handrails and buttons. more cost and lower sustainability. regular disinfection of railway stations uses harsh cleansers, which are expensive and some of which are not environmentally friendly. public misconception. the us national institute for occupational safety and health (niosh) has classified tio as a "potential occupational carcinogen", which produces a public misconception regarding its safety-workers need to wear protective clothes while spraying nstdc, but once dried it is completely safe. silver resistance. there are recent investigations that are addressing issues related to microbes that can develop resistance against silver nanoparticles, which can compromise its long term effectiveness. no international standardized testing. lack of standardized tests to assess the long term potential environmental impact of nanoparticles (because there are different formulations of different compositions using different synthetic techniques). efficiency on a broad spectrum. nstdc is certified to be effective in killing a wide range of bacteria, viruses, and mold including the h n influenza virus. huge investment. mtr corporation attempted to invest . million dollars in nanotechnology products to enhance the hygiene levels of hong kong stations, especially that nanoparticles maximize effectiveness. regulated materials. nstdc's main component, titanium dioxide (tio ), has been approved for use in foods by the fda and under the public health and municipal services ordinance in hong kong. promising results. preliminary tests on hong kong subway cars coated by nstdc showed % reduced bacterial infections. durability. the nstdc nano formula is stable and does not require frequent replacement; therefore it is sprayed every years and is checked regularly every months. wider adoption. nstdc, promising antimicrobial efficiency, makes it suitable to be applied in mtr-managed shopping malls, staff offices and recreational facilities to ensure the highest cleanliness standards for passengers, customers and staff. what's next? mtr plans to monitor the coatings in hong kong in attempts to apply them in its two new uk rail franchises-london rail and west midlands. palais royale: india's first green super-tall residential building. hydrophobic concrete plays an important role in the rapidly growing building industry in india. • concrete is porous and by time, it absorbs water causing it to corrode and crack. hycrete admixtures (chemical mixtures added to concrete) are hydrophobic nanostructured mixtures that create a waterproofing seal on the concrete's internal capillaries preventing water penetration. similarly, they protect steel reinforcement bars by creating protective coatings around them. nanotechnology • nanostructured cement in liquid admixtures: when the concrete hardens, the admixture turns from liquid to a solid bonded to concrete. • "palais royale" is the first skyscraper to achieve the platinum leed certificate from the indian green building council. rapidly emerging market. the construction boom and the damp environment in india make it an ideal customer for hycrete. it is worth mentioning that in alone, around projects made use of hycrete. cost of corrosion. the us spends billion dollars annually on corrosion related problems and the federal republic of germany spends % of its gross national product on corrosion [ ] . leed motif. builders and architects all over the world seek to earn leed credentials. india has become an advanced entrant in the leed race. environmental impact. external protective coatings on concrete are usually petroleum based and thus compromise the ability to recycle concrete. in addition, they release vocs (volatile organic compounds) into the surrounding environment. still needs to be greener. hycrete technology does not play too impactful of a role in reducing carbon emissions associated with making concrete. very slow adoption rate. the construction market is somewhat conservative and diffuse, especially in india: high quality construction is not yet fully appreciated on a large scale. risky investment. the construction market in developed countries is well established. consequently, developing countries are the main target. however, the concepts of green nanotechnology innovations are not easily implemented or understood in most developing countries. uncertain feature. some studies on hycrete suggested that its compressive strength is reduced by - % yet is still suitable for most construction applications [ ]. india is getting rich. the construction boom in india was mainly triggered by the rapid growth in the middle-income class as well as the increasing wealth of the country. high level testing. hycrete went through over years of independent and sponsored tests, mostly funded by us federal highway administration. all of these tests showed promising results. according to the british standard absorption test bsi - , hycrete had less than % water absorption [ ] . gold certificate. hycrete is the first material certified by cradle-to-cradle gold certification because it is easy to recycle and it adds leed points to projects. cost and time saving. the admixture is built within the concrete that is batched at the plant not at the job site. thus it saves costs of extra containers and materials compared to the case of applying external coatings at the job site. business boom. the palais royale project greatly boosted the hycrete business. the project required , gal of hycrete and the company gained more than one million dollars. cost efficiency. the installation process of hycrete in the "palais royale" project was fast and cost effective because the amount of hycrete needed per square feet was % less than the amount needed for the external waterproofing membrane solutions. operational impact. implementation of nanostructured admixtures in hycrete decreases the amount dosed in concrete ( gal per cubic yard of concrete) reducing the time, cost, and waste of operations [ ] . internal impact. the application of hycrete is expected to enhance the longevity and durability of the skyscraper's infrastructure. what's next? the underdeveloped construction market in india along with hycrete's success in indian projects is driving private equity firms to joint venture with hycrete, inc. hycrete's achievement in india is setting it as a role model for the emerging construction markets in the middle east. bioni paints dubai discovery gardens. a , square meter residential community in dubai "discovery gardens" decided to use the antimicrobial bioni paints. bioni using nanotechnology, managed to stabilize and integrate silver nanoparticles in paints. it used the smallest possible microbicidal amount to prevent yellowish discoloration of paint. silver nanoparticles bound to paint: tiny particles of silver that are very active in killing microbes. the residential community is built with an antimicrobial durable nanocoating that is resistant to cleansing chemicals and is nonflammable [ ] . greener long lasting alternative. traditional antimicrobial coatings containing biocides have short life spans and slowly diffuse into the environment posing human and environmental risks. metropolitan growth. in dubai, there is a continuously growing construction activity with buildings of truly immense proportions, which makes it a valuable customer for bioni antimicrobial paints. desert kingdom. although dubai employs high quality construction work, the hot climate and high humidity create an ideal medium for the growth and propagation of mold and microbes inside buildings. sbs. the sbs (sick building syndrome) is strongly related to contaminants and pollutants released from indoor sources [ ] . aesthetics and efficiency. the difficulty of maintaining a high enough concentration of nanosilver to efficiently exert an antimicrobial effect yet low enough to prevent yellowish discoloration. high cost. although bioni antimicrobial paints in hospitals are % more cost effective because they decreased the frequent use of biocides, they are more expensive in residential buildings. superbugs. even though tests have shown that bioni antimicrobial paints killed more than % of staphylococcus aureus on the paint surface, still there were no appropriate field tests carried out to test activity against superbugs (microbes resistant to multiple antibiotics). applied materials research in bremen) and in bioni cs have spent more than years developing processes for manufacturing the antibacterial nanosilver particles and for incorporating them successfully into paint solutions. broad microbicidal effect. bioni antimicrobial paints are volatile organic compounds, free of antiallergic, antiviral and antibacterial effects. nanosafety. the nanotechnology innovation in the paint ensures nanosafety by trapping the nanoparticles in a polymeric matrix, thus there is no fear of release into the surroundings. furthermore, the coating is certified by tÜv rheinland signet ensuring that it is emission free and does not release any substances into the environment. dubai municipality testing. the national building authority of dubai-the dubai municipality-conducted its tests on bioni products yielding promising results. maintain building integrity. the innovative paints proved to be the best fit with building materials because they are resistant to abrasion (wet abrasion resistance class ) and disinfection chemicals. additionally, they are not flammable (building material class a ). extra cost efficiency. according to dubai municipality testing, bioni's nanosilver technology has low thermal conductivity and can reflect up to % of the incident light, thus lowering air conditioning bills. growing market in dubai. on july th , bioni was officially recorded in the emirate's commercial register marking an excellent opportunity for bioni to expand its activities in the gulf region. what's next? although bioni antimicrobial paints were designed to target medical facilities, bioni they can find applications in other sensitive buildings such as children's bedrooms, schools, kindergartens, bathrooms, showers and toilets, the food industry, and retirement homes for the elderly. société générale bank in switzerland utilized m nano-based uv absorbing window films to solve the problems of its overheated indoor working environment. hundreds of ultra-thin layers made of advanced nanoceramics that can reduce heat and ultraviolet light transfer were installed. at the same time, they preserve interior and exterior window views. nanotechnology nano-based advanced ceramics: they filter out − % of infrared (ir) and uv radiations, while maintaining the transfer of visible radiations [ ] . the new windows reduced cooling costs, contributed to the environment, and maintained their healthy indoor environments. nowadays' impractical alternatives. conventional reflective films are either metal based, which interfere with electronic signals and corrode in coastal regions changing the window color, or dye-based, which fade over time. sustainability. energy costs are increasing, and there is a great need for sustainable energy efficient solutions especially from the building sector which is one of the main detrimental influences on the environment. first patency. m is the first company to earn the world's first patency in window films over four decades ago. since then, the company has been producing reliable solutions to lower customers' energy costs and to provide an accelerated return on investment. year commercial warranty, encouraging its rapid commercialization and adoption. leed. m window films are components of leed sustainable design where buildings can earn - points [ ]. indoor environment. up to % of total uv energy and more than % of the heat producing ir energy were rejected. the bank had better and sustainable indoor temperature control. furthermore, fabrics and furnishings were protected against uv induced damage. cost effectiveness. société générale bank enjoyed a unique and green approach to reduce energy consumption with a valuable return on investment. mission accomplished. the bank managed to improve the indoor working environments without compromising the specific historic and aesthetic features of the old building. green impact. the building industry is a top contributor to worldwide carbon emissions. building insulations could save around % of energy consumption and consequently reduce carbon emissions [ ] . what's next? the growing regulations on the building sector to save energy drive the growth for solar control window films, which is forecast to be an million dollars market by . first technology providers like m are likely to be market leaders, and early adopters in the construction market will enjoy a unique position [ ] . cleaning using forces of nature. an innovative glass makes use of rain and sun to self-clean and resist dirt. • innovation pilkington developed nano-films made of a photocatalyst that can interact with ultraviolet (uv) rays to break down organic dirt. the innovative film also contains a hydrophilic (water loving) component that can attract water or rain on its surface forming sheets that dry without spotting. the technology used nano films ( − nm) made of microcrystalline titanium dioxide. titanium dioxide in the presence of uv produces radicals that degrade organic pollutants to nontoxic products. ever since pilkington introduced their self-cleaning glass windows, they have been experiencing accelerated adoptions of their windows and a growing customer base. environment friendliness. pilkington self-cleaning windows eliminate the need for noxious chemicals that are washed off into the environment after the cleaning process. consumer convenience. self-cleaning windows are forecasted to be more rapidly adopted in construction compared to other types of smart windows: consumers can rapidly see the cost efficiency associated with the decreased frequency of cleaning windows compared to that associated with energy savings in other types of smart windows. emerging market. the market for self-cleaning windows is not yet mature, with few players, thus, there is a great opportunity for growth and expansion for early entrants. regional limitation. the photocatalytic material used will not function properly in the presence of inorganic dirt, long spells, coastal areas and internal windows because it needs daylight. since self-cleaning technologies in windows are new features and no quality standards are there to assess their efficiency, a consumer's decision will be reliant only on the manufacturer's claims. high cost. pilkington self-cleaning windows are - % more expensive than conventional glass, which can negatively influence the buyer's purchasing decision. market upset. glass cleaning companies are an important component of the glass windows "value chain". thus, the introduction of self-cleaning windows will affect their businesses negatively. enablers r&d. pilkington's expertise through - years of extensive r&d on thin film technologies enabled it to successfully transform them from laboratory samples to the market. safe material. titanium dioxide is publicly and governmentally accepted because it has been widely used in food related materials, cosmetics, and toothpastes. attraction of unique customers. saint pancras station in the united kingdom is one of the customers that has applied the self-cleaning glass. it installed the glass on its roof and building structure to reduce maintenance costs. technology appreciation. pilkington was one of the four finalists for the royal academy of engineering's macrobert prize that rewards technological and engineering innovation. new added benefit. pilkington photocatalytic effect could naturally also depollute the surrounding air by decomposing some pollutants such as formaldehyde and ground level ozone. pilkington is working with other glass manufacturers, universities, and standards' institutes to develop standards that assess and measure the self-cleaning properties of nanocoatings in an attempt to increase the public trust (so as not to be only reliant on the manufacturer claims) and the commercial adoption of these products. moreover, self-cleaning glass can be integrated with solar panels to reduce their frequent cleaning costs, and to make use of the same solar radiations. lumotone invented new transparent shutter films that are stuck on window made opaque by the click of a button. lumotone inc. has designed a film that can be applied to a glass surface and can be converted to opaque color upon switching it off. it can also be tailored to be colored or be used to show a projection, switched on and off using a mobile device. the innovation is based on a film containing polymer dispersed liquid crystals (pdlc) i.e. small nanoparticles of liquid crystals dispersed in a polymer as shown in fig. . . how such liquid crystals work: in a typical pdlc, there are many crystals with different orientations and configurations that scatter light giving an opaque appearance. these crystals become aligned when an electric field is applied allowing the light to pass through and giving a transparent appearance. an efficient invisible window blind that can be turned on and off by the press of a button. the need for privacy. window blinds are important house amenities to prevent people from prying into other people's lives. new décor trends. the new futuristic décor trends constitute less furnishings, wide spaces and invisible blinds instead of curtains that can be controlled by the press of a button. the need to save energy. by controlling the amount of light entering the room, you can ensure the room stays cool in the summer and warm in the winter thereby reducing the energy needed to maintain a room's temperature. the need for automation. since the advent of remote controls, computers and mobile phones people have come to rely more and more on automation. this is further increased by the modern fast pace of life. numerous people nowadays install home automation systems to make their life more comfortable and easy. uv blockade. nanoshutters block % of uv light entering through the glass. this in turn is healthier as well as crucial to preventing the fading of colors of the interior décor and fabrics of furnishings inside the house. installation. the difficulty of installation of the nanoshutter will definitely affect its success. however, lumotone, inc. has made the nanoshutters easy to install-as easy as putting up a poster on the wall. they also provide certified professionals who can install them for their customers. automation. how to make these smart windows automated and be controlled by your mobile device remotely when you are away from home. durability. the durability of the nanoshutter film and whether it can withstand cleaning by household solvents is a limitation. this explains why such films are protected by an upper layer to prevent them from being scratched or destroyed. in addition, the company provides directions as how to clean such smart windows; which solvents are allowed or not allowed. research. the founders of the company were originally researchers and engineers in the field of nanotechnology in the university of waterloo, canada, giving them credible backgrounds to design such products. nanoshutters that can be integrated with home automation systems. lumotone developed their nanoshutters to be compatible with any home automation system. mobile applications for the nanoshutters. lumotone has also designed mobile applications and computer software that enable the users to control their shutters in or away from their homes. auto-scheduled nanoshutters. lumotone has made its shutters to be schedulable by computer or mobile application so a user can sleep in shaded windows and wake up in bright sunlight early in the morning to go to work. the efficiency of nanoshutters made them invade other market sectors including automotive and aircrafts. these smart windows help to control the inside cabin temperature as well as prevent screen glare when watching videos. what's next? lumotone is further developing its technology to produce pixels and transparent electronic displays. nanotechnology for green building. green technology forum environmentally intelligent integral waterproofing and corrosion protection for concrete. clean technology opportunities and challenges for solar control films key: cord- -z ekgtv authors: babu, tara m; perera, ranawaka a p m; wu, joseph t; fitzgerald, theresa; nolan, carolyn; cowling, benjamin j; krauss, scott; treanor, john j; peiris, malik title: population serologic immunity to human and avian h n viruses in the united states and hong kong for pandemic risk assessment date: - - journal: j infect dis doi: . /infdis/jiy sha: doc_id: cord_uid: z ekgtv background: influenza a pandemics cause significant mortality and morbidity. h n viruses have caused a prior pandemic, and are circulating in avian reservoirs. the age-related frequency of current population immunity to h viruses was evaluated. methods: hemagglutinin inhibition (hai) assays against historical human and recent avian influenza a(h n ) viruses were performed across age groups in rochester, new york, and hong kong, china. the impact of existing cross-reactive hai immunity on the effective reproduction number was modeled. results: one hundred fifty individual sera from rochester and from hong kong were included. eighty-five percent of patients born in rochester and hong kong before had hai titers ≥ : against a/singapore/ / , and > % had titers ≥ : against a/berkeley/ / . the frequency of titers ≥ : to avian h n a/mallard/england/ / and a/mallard/netherlands/ / in subjects born before was % and %, respectively. there were no h hai titers > : in individuals born after . these levels of seroprevalence reduce the initial reproduction number of a/singapore/ / or a/berkeley/ / by %– %. a basic reproduction number (r( )) of the emerging transmissible virus < . predicts a preventable pandemic. conclusions: population immunity to h viruses is insufficient to block epidemic spread of h virus. an h n pandemic would have lower impact in those born before . influenza pandemics may occur when influenza a viruses of animal origin with a novel hemagglutinin (ha, or h) with or without neuraminidase (na, or n) subtypes to which the human population has little or no immunity infect humans and transmit efficiently from person to person. there were influenza pandemics in the th century. in , an influenza a virus of the h n subtype emerged and caused widespread disease; subsequently, h n viruses caused seasonal epidemics until . in a new influenza a virus of the h n subtype, sometimes referred to as the "asian" influenza, emerged to cause a second pandemic, and subsequently h n viruses replaced h n viruses as the cause of seasonal influenza from to . in a third pandemic was caused by an h n virus, which replaced h n viruses and continues to circulate in humans to the present day. influenza a pandemics are associated with significant mortality, morbidity, and financial burden. for example, the pandemic of - resulted in at least million influenza-related deaths [ ] , while the pandemics of (h n ) and (h n ) combined had estimated economic losses around us $ billion (estimated in dollars) [ ] . although not designated a pandemic, the reemergence of h n in also shared some characteristics with the other pandemics. the h n pandemic was caused by a virus subtype that was then circulating in humans and was unexpected because it was generally assumed that that population immunity would prevent emergence of a pandemic virus of a subtype currently endemic in humans. there continues to be concern regarding the potential for new influenza a viruses to be transmitted to humans, with documented severe zoonotic disease caused by influenza a h and h infections. however, because h n virus has already caused a pandemic, and h subtype viruses are currently circulating in wild and domestic birds [ ] , reemergence of an h n virus is one of the most likely scenarios for a new pandemic. anti-ha antibody, anti-na antibody, and cell-mediated immunity have all been correlated with protective immunity in both experimental animals and in humans [ ] [ ] [ ] [ ] . anti-ha antibody in peripheral blood sera, as assessed by the hemagglutination inhibition (hai) assay, has a strong correlation with protection against influenza infection and disease. although complicated by significant interlaboratory variation, an hai titer of : is generally accepted as a marker of reduced susceptibility [ ] . therefore, analysis of the population level of hai antibody can be used to estimate the population susceptibility to infection [ ] . for example, the seroprevalence of hai antibody to ph n in individuals older than years correlated with a significantly decreased influenza-associated mortality for these individuals during [ ] . it has been suggested that exposure to antigenically related h n influenza virus - years earlier provided older adults with some degree of immunity against the h n pdm virus [ ] . similarly, individuals who were exposed to h n viruses during the period from to may have persistent antibody to these viruses and be relatively protected from an emerging h n virus. however, more than two-thirds of the world population in was born after [ ] , suggesting that there may be substantial susceptibility to these viruses. because pandemics spread across the world within weeks after emergence [ ] , much faster than the process of developing and rolling out a vaccine to the newly emerged pandemic virus, which takes > months [ ] , attention has recently focused on developing systematic risk assessment algorithms for animal viruses of possible pandemic threat so that preemptive preparations including the development of vaccine seed strains can be initiated in advance. examples of these include the influenza risk assessment tool and the tool for influenza pandemic risk assessment [ ] . an integral aspect of this risk assessment process is assessment of population immunity to the relevant virus. in this study, we evaluated population immunity using hai assays against human and avian h n influenza strains in different age groups in the united states and hong kong. we then estimated the impact of existing cross-reactive hai immunity on reducing the effective reproduction number (r) of a potentially pandemic h subtype virus and characterized the minimum basic reproduction number (r ) that such a virus must possess to cause a pandemic. samples in rochester were collected between january and march from nonimmunosuppressed individuals who were healthy or had stable medical conditions and were from months to years of age. in the united states, influenza activity typically peaks in january or february. according to the centers for disease control and prevention, in - influenza activity peaked in early february and in - it remained low through february and did not peak until mid-march. in - , - , and - , influenza activity peaked in late december with some variability [ ] . sera from children and adults in hong kong were collected as part of a previous serological study between august and december , prior to the winter influenza season, which typically commences around february-march in hong kong [ ] . the preceding influenza season peaked in february-march and the dominant virus subtype was pandemic h n . two hundred ninety-five serum samples from this study were selected for testing in age strata. selection of viruses for hai testing was based on phylogenetic lineages of the h influenza virus subtypes: human and avian eurasian lineages. viruses were selected from each lineage to represent temporal and geographic diversity. a/singapore/ / (h n ) and a/berkeley/ / (h n ) represented the human lineage, whereas a/mallard/ england/ / (h n ) and recent h n virus isolate a/ mallard/netherland/ / (h n ) were of the eurasian avian lineage [ ] . the a/mallard/england/ / virus was generated by plasmid-based reverse genetics with ha and na of a/ mallard/england/ / and other internal virus genes of a/ puerto rico/ / origin. antigenic relatedness of the selected test viruses was determined by reciprocal hai assays shown in supplementary table . viruses with pandemic potential were handled in a us department of agriculture-approved animal biosafety level (absl )-enhanced facility. β-propiolactone (bpl)-inactivated virus using standard procedures for use as antigen in the hai test was prepared. the bpl-treated virus preparation was inoculated into -day-old hen's eggs following standard virus culture procedures to confirm complete inactivation of the virus. the antigen was then removed from the absl -enhanced laboratory for hai analysis. in rochester and hong kong, hai studies were performed in biosafety level conditions. serology hai tests were performed using turkey red blood cells in rochester, and chicken red blood cells in hong kong, otherwise the laboratories used the same procedure for the test. sera were pretreated with receptor-destroying enzyme (denka seiken co ltd) and tested at a starting dilution of : . hai was performed using "v" bottom microtiter plates as previously described [ ] . the positive control sera used were ferret hyperimmune sera against a/kruitt/ , a/mallard/netherlands/ / , a/swine/ missouri/ / , a/mallard/netherlands/ / , and a/bakker/ viruses, and goat hyperimmune sera against a/ japan/ / and a/singapore/ / . negative controls consisted of antigen alone wells and the reagent control contained phosphate-buffered saline with red blood cells. statistical significance was analyzed using graphpad prism software (graphpad, san diego, california) using -way analysis of variance, followed by bonferroni post hoc analysis. p values <. were considered statistically significant. the reproduction number of each virus in each population was calculated as follows. we partitioned the population into n = age groups ( - , - , - , - , - , - , - , ≥ ) and m = hai titer levels (< : , : , : , ≥ : ). let p i be the proportion of population in age group and s ij be the proportion of age group i with the jth hai titer. the age distribution p i was based on the most recent census data from the united states ( ) and hong kong ( ). to estimate s s for each age group, we used bayesian inference with dirichlet y i was the number of individuals in age group i in our serologic study and x ij was the number of subjects in age group i with the jth hai titer level [ ] . we assumed noninformative priors, that is, all priors were dirichlet distributions with parameters a j = for j m = ¼ , , , and hence the joint posterior distributions of s s we assumed that an hai titer of < : , : , : , and ≥ : reduced susceptibility by %, %, %, and %. as such, the proportion of the population that were immune was ij j , where z j was the reduction in susceptibility conferred by the jth hai titer level (ie, , and z = . ). the basic reproduction number r was the largest eigenvalue of the matrix q ij { } , where q ij was the average number of secondary cases in age group i generated by an infector in age group j when everyone in the population was susceptible [ ] . we constructed the matrix q ij { } using the united kingdom social contact matrix [ ] because analogous data are not available from the united states and hong kong. because the immune proportion of age group i was table . the demographics of the study population matched the demographics of the source population (data not shown). the results of hai testing of the sera from rochester and hong kong gave very similar results, despite the populations and different laboratories. the geometric mean titers (gmts) of antibody in the populations against the test viruses by decade of birth are shown in table . as expected, there were substantial levels of anti h hai antibody in the sera of persons old enough to have been infected with h n viruses between and , and essentially no detectable antibody in persons born after . among persons born before , the gmt of antibody against the early human a/singapore/ / was significantly higher compared with titers against the later human a/berkeley/ / virus, whereas in persons born from to there was a trend toward relatively higher titers against the a/berkeley/ / virus. titers against the avian h n viruses were lower. there were no significant differences in the gmt against a/singapore/ / , a/berkeley/ / , or a/ mallard/england/ / in sera tested in hong kong and rochester, but sera tested in rochester had significantly higher titers against a/mallard/netherlands/ / than the sera tested in hong kong. the prevalence of titers ≥ : against the test viruses is shown for sera from rochester and hong kong in persons born before the h n pandemic, during the years that h n circulated ( - ), or after is shown in figure . ninetyeight percent of individuals from rochester and hong kong born before had titers ≥ : against the a/singapore/ / virus, whereas > % of subjects born between and had titers ≥ : . in contrast, none of those born after had titers > : to a/singapore/ / . generally, persons born prior to had a lower prevalence of titers ≥ : to a/ berkley/ / , while the prevalence of titers ≥ in persons born during circulation of these viruses was similar against a/ ( ) ( ) - ( ) ( ) - ( ) ( ) - ( ) ( ) - ( ) ( ) - ( ) ( ) or later ( ) ( ) data are presented as no. (%). singapore/ and a/berkley/ . the prevalence of titers ≥ : against the avian h n viruses tested were significantly lower in these groups. no person born after had titer > : against any of the h viruses. after combining the results from both populations, the cumulative distribution of antibody titers against the test viruses in these age groups is shown in figure . eightyfive percent of individuals born in both the united states and hong kong before had hai titers ≥ : against a/ singapore/ / ( figure ). more than % of subjects had hai titers ≥ : to a/berkeley/ / if born before . the frequency of titers to avian h n viruses was %, and % of subjects born before had titers of ≥ : to a/mallard/ england/ / and a/mallard/netherlands/ / , respectively, with such titers seen in % and % of individuals born from to . successful pandemic emergence and spread of a virus depends on the proportion of the population that is immune and the initial r of the potentially pandemic strain. the median r for the a/h n pandemic was . (interquartile range [iqr], . - . ) [ ] . to assess the impact of these age-dependent population immunity profiles on the pandemic potential of each of these viruses if they were to emerge in the human population, we computed the impact of population immunity in reducing r (figure ). the current population immunity in the united states and hong kong would reduce the initial r of a/singapore/ / by around % ( %- %) and that of a/ berkeley/ / by around % ( %- %). as such, a pandemic of a/singapore/ / and a/berkeley/ / would be prevented if initial r of the emerging virus was below . ( . - . ) and . ( . - . ), respectively. the threshold r below which a pandemic with the avian subtype h viruses a/mallard/england/ / and a/mallard/netherlands/ / would be prevented was slightly lower. the comparability of data from geographically separated areas of the world, rochester and hong kong, argues for the representativeness and generalizability of such studies that aim to assess population immunity to viruses of pandemic concern. our study suggests that those individuals born prior to or during the period of h n virus circulation were more likely to have higher hai titers against the human h n viruses than those born after when h infection in humans had been displaced by the h n virus. in our study, we also confirmed evidence of cross-reactive hai antibodies to unrelated avian h viruses, albeit at lower prevalence and titer. the prevalence of such cross-reactive antibodies was higher in those born prior and the gmt of these cross-reactive antibodies was higher in those born prior to than in the birth cohort of - . this is possibly because those who were infected in the early pandemic waves of the h n virus in - were reinfected some years later by antigenically drifted h n viruses, possibly broadening cross-reactive immunity. as reported by others, we also observed low hai titers < : spanning across the age groups and this could be due to nonspecific data are presented as geometric mean titer ( % confidence interval). a samples in hong kong and rochester were tested at a starting dilution of < : and negative tests are given an imputed value of . inhibition by the sera. however, we checked the sera for nonspecific agglutinins where about % of the samples contained nonspecific inhibitors. since the assays were run on sera which were confirmed not to contain nonspecific inhibitors, these low titers may be due to a certain type of antigen exposure that needs further investigation. sera from those born after had higher hai titers to a/berkeley/ / than to a/singapore/ / whereas the converse was true in those born before . the older group of individuals who were first infected by a/singapore/ / like viruses likely had a boost of these titers when they were subsequently infected by later drift variants (ie, a/ berkley/ / -like viruses), the phenomenon known as "original antigenic sin" [ ] . the broader cross-reactivity may also occur due to targeting different antigenic sites, as a recent study points out that antibody response against h is mainly to the receptor binding domain resulting in a greater degree of cross-reactivity whereas for h or h viruses it is the hypervariable regions of ha resulting in a lesser cross-reactivity [ ] . soon after the h n pandemic of , studies done on sera collected prior to this pandemic were carried out and it was reported that people born prior to had detectable hai antibody to h viruses. it was therefore suggested that the historical pandemic that was believed to have occurred in - was likely caused by an h subtype virus [ ] . this prior exposure has also shown to elicit cross-reactive antibody for h strains that are currently circulating in animals, potential candidate pandemic stains [ ] . sera tested in rochester yielded higher titers against a/mallard/ netherlands/ / than the sera tested in hong kong. the differences between laboratories are not unexpected given the known laboratory-to-laboratory variation in the hai test, and what remains remarkable is the closeness of results. one technical difference between the laboratories was the source of erythrocytes for the hai test; rochester used turkey erythrocytes whereas hong kong used chicken erythrocytes. it is not known if this may contribute to this difference in hai test results. an alternative reason for the discrepancy in titers between countries may be attributed to variation in vaccination rates. vaccine uptake in hong kong is lower than in the united states. potentially, repeated vaccination may increase cross-reactive antibody to this avian h strain. assuming that the h seroprevalence in rochester and hong kong reflects global population seroprevalence, we modeled the impact of such immunity on possible emergence of an h n pandemic. this model was based on the candidate pandemic h strain originating from escape of the human adapted h n virus or from the avian gene pool that acquires transmissibility in humans. we estimate that the current levels of population immunity would reduce r of a/singapore / / - a recent risk assessment for viruses currently known to be circulating in wild birds has been carried out and the risk of these viruses acquiring transmissibility in humans was assessed to be low; most isolates replicated in human bronchial epithelial cells and ferrets. several did transmit between ferrets by direct contact, but all has retained a preference for avian-like α , -linked sialic acid receptors [ ] . these viruses still remain primarily in wild birds and have not been established in mammalian species including swine. our study provides the systematic assessment of the impact of human population immunity that goes toward such an overall assessment of pandemic risk. a limitation of the study is that other potential contributors to population immunity, such as cross-reactive na-inhibiting antibody, stalk-specific antibody, cell-mediated immunity, and heterosubtype reactive hai or neutralizing antibody [ ] [ ] [ ] [ ] ] , were not assessed. furthermore, in many parts of the world (especially in developing countries), the proportion of individuals born in or later might be larger than that in rochester and hong kong. the level of immunity against a(h n ) in these populations would be lower than that estimated here and the pandemic potential of a(h n ) in these populations would thus be higher than estimated here. in summary, we find that levels of population immunity to h subtype viruses are not substantial enough to block epidemic spread of an h virus that had acquired efficient transmissibility between humans. furthermore, the existing levels of population immunity to h viruses will continue to decline with new birth cohorts being added to the human population. given that human-adapted h n viruses that arose subsequent to the pandemic are present in many laboratories worldwide, these findings support the need to have preparedness for h viruses as a credible pandemic threat. the approach used in the case study of h viruses is more broadly applicable in defining the impact of population immunity to viruses to which there is some level of cross-reactive hai antibodiesfor example, swine h and h viruses and avian h n viruses [ ] . reliable methods for assessing population immunity are a key to reliable risk assessment of viruses for pandemic threat. it was the lack of such risk assessment of population immunity to the h n triple reassortant swine viruses that led to these viruses not being recognized as potentially pandemic viruses prior to ; indeed, it was the triple reassortment swine ha that was the key protective antigen for the h n pandemic virus. supplementary materials are available at the journal of infectious diseases online. consisting of data provided by the authors to benefit the reader, the posted materials are not copyedited and are the sole responsibility of the authors, so questions or comments should be addressed to the corresponding author. figure . estimations of overall population-level immunity against h viruses and the potential impact of population immunity on reproduction number, using potential titer cutoffs for % immunity. bars updating the accounts: global mortality of the - "spanish" influenza pandemic origin of the pandemic h influenza a virus and the persistence of its possible progenitors in the avian reservoir correlates of protection to influenza virus: where do we go from here? antibody to influenza virus neuraminidase: an independent correlate of protection preexisting influenza-specific cd + t cells correlate with disease protection against influenza challenge in humans cellular immune correlates of protection against symptomatic pandemic influenza seroprevalence to influenza a(h n ) virus-where are we? complex patterns of human antisera reactivity to novel h n and historical h n influenza strains cross-reactive antibody responses to the pandemic h n influenza virus vaccinate for the next h n pandemic now the infection attack rate and severity of pandemic h n influenza in hong kong pandemic preparedness and the influenza risk assessment tool (irat) relative incidence and individual-level severity of seasonal influenza a h n compared with pandemic h n adaptation of pandemic h n influenza a viruses in humans world health organization. manual for the laboratory diagnosis and virological surveillance of influenza the bugs book: a practical introduction to bayesian analysis inferring influenza infection attack rate from seroprevalence data social contacts and mixing patterns relevant to the spread of infectious diseases estimates of the reproduction number for seasonal, pandemic, and zoonotic influenza: a systematic review of the literature original antigenic sin responses to influenza viruses host versus flu: antibodies win a round? pre-epidemic antibody against , strain of asiatic influenza in serum of older people living in the netherlands studies on the content of antibodies for equine influenza viruses in human sera risk assessment of h n influenza viruses from the avian reservoir safety and antigenicity of whole virus and subunit influenza a/hong kong/ / (h n ) vaccine in healthy adults: phase i randomised trial key: cord- -erbftqgh authors: lau, stephen s.y. title: physical environment of tall residential buildings: the case of hong kong date: - - journal: high-rise living in asian cities doi: . / - - - - _ sha: doc_id: cord_uid: erbftqgh increasing urban populations, scarcity of urban land, depletion in resources and severe impact of urban development on sustainability are critical contemporary issues. such issues have vast implications on the desirability of compact, high-rise high-dense built forms. yet, the environmental quality and social acceptance of these forms remain barely studied. this chapter reviews some of the critical environmental implications posed by the closely packed high-rise building and high urban densities. to the physical form, urban morphology would also study social forms, which are expressed in the physical layout of a city, and conversely, how physical form produces or reproduces various social forms. urban morphology is at times considered as the study of urban fabric, as a means of discerning the underlying structure of the built landscape. this approach challenges the common perception of unplanned environments as chaotic or vaguely organic through an understanding of the structures and processes embedded in urbanization. it is widely accepted that there is a close relationship between shape, size, density and uses of a city and the sustainability of that city. however, this chapter is limited to the characteristics of a high-rise, high-density compact urban environment: hong kong and its environmental implications. it is said that urban intensification creates frequent walking trips and better accessibility to facilities (masnavi, ) . in a compact city the reduction in car ownership, vehicular trips and increase of pedestrian and transit use alleviate the environmental consequences associated with the automobile. compact city has many advantages such as conservation of countryside, reduced need to travel by car and thereby reduction in fuel and pollution, support for public transport, walking and cycling, better access to services, more efficient utility and infrastructure provisions, and revitalization and regeneration of urban areas (burton, ) . in contrast to compact city, dispersed cities suffer from inefficient transport management and long commuting trips, which lead to a high dependency on automobile high energy consumption and pollution (newman & kenworthy, ) . although high density combined with mixed use allows for high accessibility to a majority of users, the mixing and co-location of incompatible uses such as housing, community, recreational and public spaces near commercial, industrial and transport can have consequences on the physical quality of the living environment. greater intensification has implications on urban green space. even though a valuable contributor to urban quality, urban greenery provision is often reduced under pressure from other land use development. research claims that compact city suffers from a perceived lack of greenery, open spaces and parks which provision is seen to be better in low-density environment (masnavi, ) . however, urban sprawl results in unsustainable levels of resource use and inequitable lifestyles (williams, burton, & jenks, ) . in comparison with urban sprawl, the compact city is a dominant model for sustainability (jenks, ) . yet, evidence on the impact of higher and lower densities on sustainability, the impact of centralized decentralized city form on sustainability are lacking. review of some city forms indicates both advantages as well as disadvantages in sustainability. for example, forms that reduce travel and are fuel-efficient may be harmful to the environment and have social inequities. they may be locally beneficial but not city-wise beneficial (williams et al., ) . the effects of urban density on the total energy demand of a city are complex and at times conflicting (givoni, ) . compactness of land use patterns will bring benefits to energy distribution and transport system design, but crowded conditions may create congestion and undesirable local microclimate (hui, ) . the compact city challenges are mainly associated with environmental quality and social acceptability (williams et al., ) . a multiple intensive land use development in hong kong is formed by an intensification of land use through mixing residential and other uses at higher densities at selected urban locations, together with an efficient transport and pedestrian network (lau & coorey, ; lau, ghiridharan, & ganesan, ) . hong kong is one of the asian cities that have evolved as a compact urban form. situated at the south-eastern tip of china, hong kong is ideally positioned at the centre of rapidly developing east asia. with a total area of , km , it covers hong kong island ( . km ), the kowloon peninsula just opposite ( . km ), and the more rural section of hong kong new territories and outlying islands ( . km ). the central part of both hong kong island and kowloon are hilly rising to a height of , m. only . % of hong kong land is built up, concentrating on the triangular tip of kowloon and the coastal strip of northern hong kong island. the total population in hong kong is , , with the median age rising from in to in (census and statistics department, ) . the median monthly household income is hk$ , . a population growth rate of approximately million is observed in every years in the last decade and the population forecast for , is million (fung, ) . although the total population density is , persons per km , urban areas hold a staggering population density of over , persons per km where certain districts rank among the most densely populated places in the world. the density of public housing reaches at least , residents per ha, which is twice the density of the most crowded residential areas in mainland china (xue, manuel, & chung, ) . high-density in a land limited country like hong kong is the norm. cities often respond to development pressure by setting targets for increased urban densities, and the establishment of high-rise cityscape and compact urban settings is unavoidable (hui, ) . a chronological classification of tall building types in hong kong can be observed. the typology includes the verandah type from the s, the cantilevered living quarters type from the - s, the rectangular mass type from the s, and the podium type from the s onwards. among the rectangular mass type and podium type buildings, several shapes of building forms are observed such as the rectangular, "y" shape, clusters and crucifix shapes. when observing the pattern of development at a district scale, two significant variations in development is observed, namely, the clusters of multiple intensive land use developments around the mass transit nodes and the linear multiple intensive land use development alongside main roads and streets in the older parts of hong kong. the cluster of a high-density multiple intensive land use (milu) development is mainly observed along (under) the three main rail lines of mass transit railway, namely, the airport railway, urban lines and tseung kwan o lines. they are three-dimensional distribution of density and land uses integrated by three parallel ( ), and wikipedia ( ) commuting levels, namely, the mass transit rail (mtr), kowloon-canton railway, subways below ground, buses, taxis, light rail transit and tramways on ground and walkways above ground which are then vertically connected via ramps, stairways, elevators and escalators. such developments are built above or connected in close proximity to mass transit railway and other public transport modes. as seen in fig. . , when several milu nodes are developed in close proximity, an interdependency is formed among these developments where land use functions and services are shared, thus creating primary, secondary and tertiary interdependent zones (lau et al., ) . plot ratios, also known as floor area ratios, of up to for commercial uses and up to for residential uses have led to buildings of up to storeys built above - level podiums. the podium levels incorporate the secondary supporting functions such as commercial, recreational, government, institutional and community (gic) land uses while the primary residential, office or hotels/serviced apartments are located above as seen in fig. . . four major types of milu developments can be discerned according to its mix of land use types: . the primary use being office and/or hotel/serviced apartments with supporting secondary commercial, gic and transport uses; . primary use being residential supported by secondary commercial, gic and transport uses; . primary use being both residential and office supported by secondary commercial, gic and transport uses; . primary uses being office, residential, hotel/serviced apartments and secondary commercial, gic and transport uses. lau and coorey ( ) these development clusters are defined as primary milu nodes (lau et al., ) . table . illustrates some examples of the four types of primary milu developments that are commonly seen in hong kong. in hong kong where the buildable land resources are scarce due to hilly terrain and scarcity of usable land, tall buildings serve as an optimal option to maximise development potentials and best returns. reduction in travel time due to intensification of mixed land uses contributes to efficiency and economic viability of the city (wu, ) . the concept of home-work-play gives the residents efficiency, convenience and savings in time. tall buildings also provide a heuristic device to meet the housing demands for the increasing population. additionally, the mixed use nature of developments creates places that are active and lively for longer duration of time, providing safe neighbourhoods and additional time for use of urban spaces for its residents. rich, vibrant urban spaces are created within neighbourhoods. urban intensification and compactness also provides savings in infrastructure and services, and high penetration of infrastructure and services for all residents. for example, it results in an overall reduction in energy use and traffic fumes (wu, ) . high-rise building rather than urban sprawl reduces the use of woodlands and forest areas for development, saving valuable land resources for future use and recreation purposes. in hong kong such country parks and woodlands can be easily accessed. yet, there are some consequences associated with tall residential built forms arising from the very high population and extreme density. both social and environmental implications are prevalent in such conditions. this chapter is specifically focused on the environmental implications and various measures and solutions that may mitigate the environmental consequences of tall residential buildings taking hong kong as a case study. high-density living in hong kong is strongly linked with significant air, water and noise pollution. drastic environmental implications such as living in busy urban centres with high air and noise pollution, poor lighting and ventilation in individual housing units, urban heat island and wind tunnel effects are observed in hong kong's high-rise building developments. one of the problems related to mixed land use developments at very high intensities is the incompatibility of uses. this problem is particularly apparent in the old built-up areas because of a lack of comprehensive planning in the past (fung, ) . examples include those residential developments that face environmental nuisance due to its location adjacent to industrial areas. another example is where highways pass through residential areas, posing the threat of noise and air pollution. probably due to poor ventilation and lighting conditions, as high as % of all electricity used in hong kong is for lighting and space conditioning (wu, ) . air conditioning accounts for one-third of the total power consumption of hong kong each year and costs hk$ billion (ching, ) . high space conditioning further aggravates the outdoor climate conditions creating a vicious cycle of environmental pollution such as urban heat island. table . outlines the positive and negative effects of high density on city's energy demand as identified by hui ( ) . current air pollution levels in hong kong are high due to the high intensity of emissions from industry and traffic as well as a lack of proper environmental planning in the past. the number of motor vehicles is increasing due to population growth and demands. many areas in hong kong are topographically confined by hills and the air pollution dispersion in these areas is inhibited (hong kong use of solar energy -roof and exposed areas for collection of solar energy are limited planning department, a). hong kong has been facing two air pollution issues: local street-level pollution caused by motor vehicles; and regional smog problem caused by motor vehicles, industry and power plants both in hong kong and in the pearl river delta. street level pollution is mainly caused by the large number of motor vehicles in highly dense urban areas. the emissions are trapped in between the very tall buildings along the streets. the tall stacks of building towers create urban walls that are barriers to wind circulation and vistas in the city. further, it causes wind tunnel effects and unsafe environments at street levels. walking at street levels in compact cities is no longer safe for the pedestrian. the high flow of vehicular traffic damages the quality of the street environment, with their high noise and air pollutants. therefore, whether within enclosed spaces or outside in the public areas and streets, the quality of the living environment is being damaged, affecting the overall quality of life. furthermore, since , there has been an increasing concern on the "wall effect" caused by uniform high-rise developments, which adversely impact air circulation. a survey carried out by the environmental group, green sense revealed that of housing estates surveyed have a "wall-like" design (yueng, ) . the survey found the estates of tai kok tsui and tseung kwan o as the best examples of this kind of design. in may , citing concern over developments in west kowloon, and near tai wai yuen long railway stations, some legislators called for a law to stop developers from constructing tall buildings which adversely affect air flow in densely populated areas, but the bid failed (wong, ) . more recently, in december , a protest against "wall-effect" for a dozen of current and planned constructions was held at central government offices (ng, ) . these protesters were also concerned about the development plans for nam cheong and yueng long stations. tall buildings also pose threats to public safety and health in terms of easy spread of disease and viruses, fire risks and domestic accidents. adequate ventilation and building maintenance are therefore an important issue for high-rise buildings in order to avoid the spread of disease and accidents associated with dilapidated structures (wu, ) . study on residents' satisfactions and aspirations of high-rise living in hong kong shows that better view, less noise, better air quality are the major reasons for people to opt for high-rise living (lau, ) . the higher selling prices for apartments on higher floors are also attributed to better views, less noise and better environmental quality. this trend may seem to suggest that residents who choose living on higher floors are seeking an escape from the environmental problems since living on higher floors allows one to be further way from the city surface. but, opting for taller buildings alone may not be a solution to the problem. there exists a strong pressure from people to improve air quality and environment. the government has acknowledged this requirement and taken measures to improve the environment. for example, it has implemented vehicle emission and fuel standards, cleaner alternatives to diesel, emission inspection and enforcements such as controlling smoky vehicles, etc. and promoting vehicle maintenance and ecodriving. in his - policy address, the chief executive of hong kong has emphasized the importance of addressing these issues in order to secure sustainable development for future generations. he has outlined some of the measures, to reduce air pollution, we have formulated the pearl river delta (prd) regional air quality management plan. this plan, prepared in partnership with the guangdong provincial government, aims to achieve specific emissions reduction targets by . we have now set up a -station air quality monitoring network in the prd. based on the data collected, the prd regional air quality index is released everyday on the internet to keep the public informed of the actual regional air quality. the data collected will also help us assess the effectiveness of our pollution reduction measures . . . in hong kong, we have imposed emission caps on power plants at castle peak, black point and lamma island. these emission caps will be progressively tightened to meet the emission reduction targets. (chief executive, . in , particulates and nitrogen oxides levels on the street have dropped by and % respectively since . the number of smoky vehicles on the road has also reduced by about % (environmental protection department, ) . increased use of mass transport and reduction in private car and taxi could help to reduce the air pollution levels caused by vehicular traffic. in addition to policy measures, urban design measures are suggested for improving air ventilation (chinese university of hong kong, ; hong kong planning department, b) . recent study identifies the following urban design issues as a means to a better quality and comfortable urban environment: lack of breezeways air paths; tall and bulky buildings closely packed causing undesirable wind breaks to urban fabric; uniform building heights resulting in wind skimming over the top of buildings and not being re-routed into the fabric; tight narrow streets not aligned with prevailing wind with tall buildings resulting in urban canyons; lack of urban permeability-with few open spaces, minimal gaps between buildings, excessive podium structures reducing air volumes at ground levels; large building blocks forming wind barriers; projections from buildings and obstructions on narrow streets and general lack of soft landscaping, shading and greenery as contributing to poor air ventilation and environmental quality in high-rise, compact built areas (chinese university of hong kong, ; hong kong planning department, b) . for better urban air ventilation breezeways in the forms of roads, open spaces, and low-rise building corridors are suggested to allow air penetration to inner parts of urbanized areas. breezeways, roads, main streets and avenues should be aligned either parallel or • to the prevailing wind directions. open spaces must be linked and aligned to form unobstructed wind corridors with low-rise structures alongside them. space between buildings must be maximized, especially in large sites with dense developments. the longer frontages of blocks may be aligned parallel to wind corridors, and non-built areas and setbacks may be introduced to further allow for good wind penetration. to maximise the penetration of sea breezes and land breeze water front sites may take special precautions to avoid blockages in wind paths (chinese university of hong kong, ) . street patterns, building heights, open spaces, density, and landscape will determine the air ventilation, solar radiation, day lighting and air temperature in compact high-rise built forms having implications on indoor and outdoor environmental quality. to illustrate, reference is made to the natural ventilation study conducted for a proposed luxury residential development in shenzhen, china. an assessment of air flow, solar energy and daylighting is done using computer based simulation tools such as airpak (usa), ecotect (uk) and radiance (usa) (lau & li, ) . table . shows the airflow study and wind velocities within the compact high dense residential site. all three graphs in table . show high age of air, indicating low ventilation and increased stagnated air. in the surrounding areas of the high-rise towers the age of air reduces when elevation height increases from to m, indicating better ventilation and cleaner air in the upper floors. the low age of air is also spread in larger proportions when the elevation height increases. as seen in the graphs, both low-and high-rise buildings form a wall that is oriented perpendicular to the prevailing wind patterns. this creates a barrier to the southeast winds and creates stagnant air in the leeward sides of the buildings. ideally, these built forms must be oriented parallel to the prevailing wind direction to ensure better ventilation and cleaner air. lower age of air and better ventilation is observed surrounding the smaller fragmented in the three diagrams above concentrated areas denote higher wind velocities. the short arrow strokes indicate low and long arrow strokes indicate high velocities. the red, yellow, green and blue strokes denote wind velocity in descending order building shapes and footprints. the areas surrounding larger blocks show high age of air and comparatively poor ventilation. in all three graphs, the row of high-rise building further away from the wind direction have a higher age of air spread in larger compositions compared to the row of buildings closer to the wind direction. observations confirm that the block size, orientations, building heights and distance from wind source affect the age of air, ventilation and air quality surrounding those buildings especially on the leeward side. the analysis can be further substantiated by the qualitative data gathered among occupants in high-rise living in hong kong (lau, ) . the general conceptions of occupants are that the apartments in higher floors are preferred due to better quality of environment -such quality can be specifically referred to as the air quality and reduced noise levels. the wind velocity graphs further confirm the observations made on the age of air distributions at varying heights. lower wind velocities are observed at low height levels. low wind velocities are also observed in the leeward sides of high-rise buildings, causing high age of air, poor ventilation and air quality in those areas. also, when the distance from wind source increases, the velocities decrease indicating the higher age of air surrounding built forms further away from the wind source. in order to enhance the wind environment in hong kong, an air ventilation issue has been included in the hong kong planning standards and guidelines. a set of qualitative guidelines and a framework for carrying out air ventilation assessment have been formulated on the basis of the air ventilation assessment study recommendations. the guidelines incorporated in the hong kong planning standards and guidelines are to strengthen the urban design guidelines for better air ventilation. the guidelines were developed according to the results of "feasibility study for establishment of air ventilation assessment system" (the ava study) was conducted and completed in . in addition to the guidelines, a technical guide for air ventilation assessment (ava) has been issued by the planning department of hong kong ( ) . ava can be used to compare the air ventilation impacts of different design options and to identify the potential problem areas for design improvements. this technical guide specifies three steps in conducting ava, i.e. expert evaluation, initial study and detailed study. the expert evaluation is a qualitative assessment based on the guidelines provided in hong kong planning standards and guidelines, while the initial study will refine the expert evaluation and the detailed study will conclude the ava. the ava technical guide recommends using wind tunnel as the tool for carrying out both initial and detailed study. however, the use of computational fluid dynamic (cfd) will be permitted in the initial study (hong kong planning department, ) . the examples of using cfd simulation in ava study are presented in table . . this study highlighted the air ventilation benefits of raising the podium level of residential buildings. the table shows the comparison of mountain and valley breezes for base case and proposed designs. according to the mountain/valley breeze simulations, we can find that the mountain can create local winds that vary from day to night if there is no background wind, which can also increase the air flow around the buildings in the mid-level. during the daytime, the air near the mountain surface can be heated up and higher than the free air far away at the same height due to the solar radiation. thus the warm air moves up along the slopes. while during the night-time, as the mountain surfaces cool down, the cold breezes can be formed and flow down the slopes. the proposed new podium can enhance the air flow through the building. it can be imagined that the building region can benefit from the mountain breezes by bringing the cooled air at night-time on hot days. the thermal environment can be improved and energy can be saved (li & yang, ) . the air ventilation and daylight penetration into individual housing units play an important role in high-rise residential building designs. many factors determine the daylight quality within housing units. study done by the students of the final year bachelor of arts in architectural studies, department of architecture university of hong kong ( kong ( / reveals several factors that determine the daylight quality within housing units. table . illustrates the types of building footprints found in high-rise residential buildings in hong kong and the evaluation of the lighting quality within a selected individual housing unit. a qualitative appraisal of the lighting quality in individual rooms of the housing unit is done by its occupant. this is combined with a quantitative -daylight simulation for the residential units showing the distribution of lighting within the spaces. the distribution of lighting quality significantly varied across the building types and spaces/rooms within the individual units. lack of sufficient lighting and ventilation in the kitchen and washrooms were a common observation. obstructions to light due to windows being covered for better privacy and furniture layout were also observed as barriers to daylighting within the spaces. some spaces have no windows at all and may be for the purpose of storage. but due to the lack of sufficient living space such spaces are also used for habitation. on most occasions, occupants use artificial lighting in such spaces even during day-time. small window sizes and fixed glazing were also commonly noted as causes for poor light and ventilation. further, it can be observed that most kitchen and toilet spaces in high-rise buildings are ventilated via "re-entrant light wells". these are equivalent to a light well with the main purpose of bringing in light and ventilation . residents most often use the window opening into re-entrants for drying clothes, etc. the inlet and outlet water pipes to kitchen and toilets are located along the re-entrant spaces. the mechanical ventilation outlets are also located along these re-entrants that act as a shaft for bringing in fresh air as well as outlets for foul air from toilets and kitchen. the building shapes play a major role in determining the re-entrant shapes (see table . for building shapes and re-entrant shapes). most often, the reentrants are too narrow and inadequate for bringing in light and ventilation. wider, more open re-entrant shapes are needed for sufficient light and ventilation. the size, number and positioning of windows, the floor area of space, windowfloor area ratio, the shape of the room and depth of space from window, internal reflectance of materials and finishes, the building footprint shape, external obstructions, building orientation, obstructions caused by neighbouring towers and distance between towers, external barriers to wind and daylight such as hills and internal furniture layouts all affect the quality of ventilation and daylighting within residential units in high-rise towers (final year bachelor of arts in architectural studies students, students, / . a common issue is windows placed within the visibility range from neighbouring blocks cause lack of privacy. as a result, most windows are kept closed and covered using opaque materials such as shades, curtains, etc. blocking light and ventilation into the housing units. tables . and . illustrate the case studies and respective daylight analyses. uneven day light distribution in several spaces within the block is caused due to window sizes and numbers, the floor area, window-floor area ratio, the location of windows, shape of building foot print, interior furniture layout and distance between blocks and block layout, contextual barriers such as hills, obstructions from other buildings also determine the lighting quality and ventilating inside housing units of high rise blocks. windows facing neighbouring blocks are being constantly kept closed due to lack of privacy, thereby does not serve the purpose of brining in light and ventilation table . day light study of high rise housing. sources: chan ( ), cheung ( , kei ( ), wong ( in addition, investigated the effect of relaxation of room height as a means for improving daylight conditions. the study investigated the relaxation of room heights from , to , mm and sustainable design features of proposed residential building located at mid-levels, hong kong. when window size remains the same and the room height is increased the day light within the room is improved but not a very significant improvement is seen. but when window size and room height is increased there is a significant increase in the daylight quality within the room. also graph shows that in room with higher room height and larger window size the day light factor shows significant increase the simulations were carried out based on the parameters: date dec (winter solstice), time : am, sky condition: overcast sky, design sky , lux. this analysis is regarded as the worst-case scenario for daylight calculation. three cases are presented in table . . the study revealed that an increase in room height has some effect on improving the daylight quality within a room. in addition, the increase of window height can make a significant contribution to the daylight quality within the room. outdoor living space of high-rise residential buildings is equally important. adequate provision of open space, greenery, vistas and visual corridors is a critical issue in the light of high land prices and the general lack of space between and around tall buildings. open spaces and landscaping on podiums are design measures taken to improve resident perceptions of open spaces, views and greenery. open spaces located close to highways, roadways, and transport nodes create poor environmental quality due to noise, dust and smoke emissions. in other words, it can be argued that even if open spaces are provided within residential blocks or outside in close proximity to homes, if its quality does not meet the demands and satisfaction of its users, such open spaces may not be efficiently utilised. podium open spaces and sky gardens create a barrier from traffic and pollution at road levels. yet, being surrounded by high-rise buildings these spaces have a tendency to trap pollutants due to a lack of cross ventilation and high building mass. the lack of green cover, trees and hard landscaping may contribute to poor micro climatic conditions in the outdoor spaces of high-rise developments (tan & fwa, ; wilmers, wilmers, / . but, people are forced to use these open spaces despite its poor environmental quality. study by davies ( ) has shown that the most popular form of recreation among hong kong residents is the use of passive local open spaces. it is observed that the majority of users of such open spaces are elderly, low income groups whose accessibility to district open spaces and country parks may be limited. study of open space satisfaction among occupants of high-rise public residential estates in hong kong by coorey ( ) shows that satisfaction of open space is primarily dependent on the physical qualities as opposed to its social qualities. the physical qualities such as climatic comfort, maintenance, facilities and provisions were identified as having important implications on their overall satisfaction. the study involved questionnaire interviews conducted in high-density public housing estates in hong kong. respondents evaluated the physical and social quality of open space and their levels of satisfaction in open spaces including those on podiums and ground level in the six high-rise developments. a comparison of open spaces located within public housing of varying density showed that occupants in higher density developments considered the physical qualities of open space such as climatic comfort, provision for open space and maintenance as having higher impact on their overall open space satisfaction. respondents living in the lower density cases tend to consider the social qualities such as safety, crowding, privacy and interaction to have a higher implication on their open space satisfaction (coorey, ) . the study highlighted the importance of environmental quality for optimum satisfaction of open spaces located within high-rise residential developments. it further highlighted that open space satisfaction among occupants living in higher density cases was significantly influenced by its environmental quality as opposed to its social qualities. such open spaces play a critical role in the lives of residents living in high-rise buildings as they are their only means of escape from the otherwise built up urban setting. additionally, its importance for the elderly and low-income groups, specifically draws on the need for optimizing the environmental quality of open spaces in high-rise developments. an increase in respondents' satisfaction with climatic comfort in open space is shown when the number of trees, the proportion of greenery is higher and the sky view factor is low due to taller buildings adjacent to smaller narrower open spaces (coorey, ) . noise pollution is a common environmental quality issue associated with mixed use and high connectivity with transport networks. taller buildings with residences in the higher floors are preferred due to less noise in the higher floors (lau, ) . also, elevated walkways and podiums serve as design principles for segregating pedestrian routes from noise and pollutant sources at street and ground levels. the podiums act as buffers from noise at ground level. the building clusters in hong kong are well integrated through elevated walkways subways and podiums that induce people to walk through buildings rather than being exposed to the fumes and noise of vehicular traffic at road levels. study of external noise measurements in the surrounding areas of an arts performing school showed that high traffic noise reflectance was caused by the façade effect and canyon effect due to high-rise built forms running parallel to the roadways (lau, ) . measurements were taken alongside two roadways on opposite sides of the arts school. one roadway has high-rise buildings located alongside it while low-rise buildings frame the roadway on the opposite side. higher noise levels are observed from the roadway with high-rise buildings. the facades of high-rise built form act as reflectors for noise sources from vehicular traffic. the taller building forms create a canyon effect causing higher noise levels. it can be suggested that the building facades, orientations with the noise sources and its noise reflectance and absorption values must be manipulated. this can be done by orientating the buildings so that it does not obstruct and reflect noise. instead, it disseminates the noise and avoids a canyon effect. the materials of the facades should be of less reflectance and higher absorption values. in addition, trees and shrubs can be introduced as noise screens alongside roadways. zoning at planning stage must be done with an awareness of the noise sources and noise reflectors in the surrounding context. habitable spaces can be buffered by elevating the units above the noise source levels. soft landscaping features such as water fountains can be used to mask and create distraction from traffic noise. although tall residential buildings have many social and environmental implications, hong kong's topography and continuous increase in population have propelled the planning and design of hong kong's built form clearly in the direction of tall buildings. but how tall and how to design such tall building is the question of concern. the general policy and regulations provoke taller buildings. but the regulations and attention of hong kong designers are turned towards more sensitive design measures that will balance the demand for taller buildings with more sensitive, sustainable and liveable design features. the critical implications for building tall are mainly associated with poor air quality, lack of wind ventilation in a macro context of a high-rise city as well as the micro context within the residential units or apartments. poor daylighting quality within tall buildings is a pressing issue for tall buildings. the lack of open space and the poor environmental quality in such open space is another issue that impacts the quantity and quality of open space among highrise occupants. the noise levels due to reflectance from high-rise towers caused by façade and canyon effects are also a challenge for zoning, orientations and design. such issues bring about specific criteria for zoning, planning and design in tall building contexts. this chapter highlighted some of the design issues and possibilities. the compact city: just or just compact? a preliminary analysis unpublished bachelor of arts in architectural studies final year projectwork unpublished bachelor of arts in architectural studies final year projectwork - policy address by chief executive. hong kong: hong kong sar government. last accessed feasibility study for establishment of air ventilation assessment system-executive summary. hong kong: department of architecture sustainable development of tall buildings in hong kong. paper presented at the tall buildings: from engineering to sustainability unpublished bachelor of arts in architectural studies final year projectwork design of open spaces in high density zones: case study of public housing estates in hong kong study of leisure habits and recreation preferences and review of chapter four of the hong kong planning standards and guidelines. final report, planning department final year bachelor of arts in architectural studies students -department of architecture university of hong kong planning for high density development in hong kong. hong kong: the planning department of hong kong climate consideration in building and urban design ifc, kornhill, telford, union square images in google earth milunet: multi functional intensive land use -principle, practices, projects, policies -towards sustainable area development. harbiforum foundation daylight analysis: residential buildings in hong kong outbreak of severe acute respiratory syndrome (sars) at amoy gardens, kowloon bay, hong kong -main findings of the investigations. department of health air quality in hong kong mtr properties. hong kong mass transit railway corporation, hong kong. last accessed technical guide for air ventilation assessment for developments in hong kong. hong kong planning department, hong kong. last accessed planning department annual report hong kong planning standards and guidelines. hong kong planning department low energy building design in high density urban cities sustainable urban form in developing countries daylight analysis: residential buildings in hong kong a survey on residents' responses to high rise living in hong kong. centre for architecture and urban design for china and hong kong traffic noise measurement for the school of performing arts sustainable building design: residential development reconsidering daylighting design parameters for tall buildings in densely built city hong kong: milu and how it is perceived policies for implementing multiple intensive land use in hong kong environmental performance analysis: proposed luxury residential development in shenzhen ventilation study of residential development at il & extension, magazine gap road, mid-levels the compact city in practice: the new millennium and the new urban paradigm is there a role for physical planners technical guide for air ventilation assessment (ava) for developments in hong kong. planning department of hong kong, hong kong. last accessed influence of pavement materials on the thermal environment of outdoor spaces achieving sustainable urban form effects of vegetation on urban climate and buildings daylight analysis: residential buildings in hong kong. unpublished bachelor of arts final year projectwork call for law against 'wall effect' fails, south china morning post policies and planning of tall buildings in hong kong. paper presented at the tall buildings: from engineering to sustainability public space in the old derelict city area -a case study of mong kok, hong kong asia's walled city' leaves -residents longing for air, the standard key: cord- - pe ou authors: yuan, chao title: empirical morphological model to evaluate urban wind permeability in high-density cities date: - - journal: urban wind environment doi: . / - - - - _ sha: doc_id: cord_uid: pe ou in this chapter, a high-resolution frontal area density (fad) map that evaluates urban permeability was produced using an empirical model, which takes into account the heterogeneous urban morphology and local wind availability. using the mm /calmet model, the wind data of hong kong was simulated, the fad map of three urban zones were calculated: podium ( – m), building ( – m), and urban canopy ( – m). wind tunnel test data was used to correlate the fad understanding of the three zones with pedestrian-level wind environment. linear regression analysis indicated that a lower urban podium zone yielded the best correlation with the experimental data, and × m was the reasonable resolution for the fad map. this study further established that the simpler two-dimensional ground coverage ratio (gcr) that is readily available in the planning circle can be used to predict the area’s average pedestrian-level urban ventilation performance of the city. working with their in-house gis team using available data, the gcr will provide the planners a way to understand the urban ventilation of the city for decisions related to air paths, urban permeability, and site porosity. . stagnant air in urban areas has caused, among other issues, outdoor urban thermal comfort problems during the hot and humid summer months in hong kong. stagnant air has also worsened urban air pollution by restricting dispersion in street canyon with high building-height-to-street-width ratios. the hong kong environmental protection department (hk epd) has reported the frequent occurrence of high concentrations of pollutants, such as no and respirable particles (rsp) in urban areas such as mong kok and causeway bay (yim et al. ). these areas also have some of the highest urban population densities in hong kong. the outbreak of the severe acute respiratory syndrome (sars) epidemic in hong kong had brought attention to how environmental factors (i.e., air ventilation and dispersion in buildings) played an important role in the transmission of sars and other viruses. since the outbreak, the planning community in hong kong started to pay more attention to the urban design process in order to optimize the benefits of the local wind environment for urban air ventilation. as a result, the hong kong government had commissioned a number of studies on this regard; the most important project among the government-commissioned studies is entitled "feasibility study for establishment of air ventilation assessment system" (ava), which began in (ng ). the primary purpose of this comprehensive chapter is to establish the protocol that assesses the effects of major planning and development projects on urban ventilation in hong kong (ng ) . the importance of wind environment on the heat, mass, and momentum exchange between urban canopy layer and boundary layer has been studied by urban climate researchers (arnfield ) . two modeling methods have been frequently applied to study wind environment of the city: wind tunnel tests and computational fluid dynamics (cfd) techniques. the united states environmental protection agency (us epa) conducted numerous urban-scale wind tunnel tests to understand the dispersion of particulate matters smaller than µm in aerodynamic diameter (pm ) (ranade et al. ). williams and wardlaw ( ) conducted a large-scale wind tunnel study to describe the pedestrian-level wind environment in the city of ottawa, canada, and identified areas of concern for planners. plate ( ) developed the boundary-layer wind tunnel studies to analyze urban atmospheric conditions, including wind forces on buildings, pedestrian comfort, and diffusion processes from point-sources of the city. kastner-klein et al. ( ) analyzed the interaction between wind turbulence and the effects induced by vehicles moving inside the urban canopy. wind velocity and turbulence scales throughout the street canyons of the city were analyzed using smoke visualization (perry et al. ) . in , the us epa's office of research and development (epa-ord) conducted a city-scale wind tunnel study to analyze the airflow and pollutant dispersion in the manhattan area (perry et al. ). kubota et al. ( ) conducted wind tunnel tests and revealed the relationship between plan area fraction (λ p ) and the mean wind velocity ratio at the pedestrian level in residential neighborhoods of major japan cities. in hong kong, the wind/wave tunnel facility has conducted numerous tests at the city, district, and urban scale to understand the wind availability and flow characteristics of hong kong (hkpd ) . apart from wind tunnels, cfd model simulation can be applied at the initial urban planning stage in providing a "qualitative impression" of the wind environment. mochida et al. ( ) conducted a cfd study to analyze the mesoscale climate in the greater tokyo area. murakami et al. ( ) used cfd simulations to analyze the wind environment at the urban scale. kondo et al. ( ) used cfd simulations to analyze the diffusion of no x at the most polluted roadside areas around the ikegami-shinmachi crossroads in japan. letzel et al. ( ) conducted studies of urban turbulence characteristics using the urban version of the parallelized large eddy simulation (les) model (palm), which is superior to the conventional reynolds-averaged models (rans). using the earth simulator, ashie et al. ( ) conducted the largest urban cfd simulation of tokyo to understand the effects of building blocks on the thermal environment of tokyo. ashie et al. noted that the air temperatures around ginza and jr shimbashi are much higher than in the surrounding areas of hama park and sumida river. ashie et al. argued that the high air temperature can be attributed to the bulky buildings at ginza and jr shimbashi that obstruct the incoming sea breezes (ashie et al. ). yim et al. ( ) used cfd simulation to investigate the air pollution dispersion in a typical hong kong urban morphology. in general, using cfd for urban-scale investigation has been gaining momentum in the scientific circle. two important documents that provide guidelines for cfd usage have been published: architectural institute of japan (aij) guidebook (aij ; tominaga et al. ) and cost action c (frank ). while the application of wind tunnels and cfd model simulations to analyze the interaction between the urban area and the atmosphere has made important contribution to the understanding of urban air ventilation of the city, such applications are costly, and may not be able to keep up with the fast design process in the initial stages of the design and planning decision-making process. instead, the outlined and district-based information based on urban morphological data parametrically understood may be more useful for planners. this chapter employs the understandings of urban surface roughness to establish the relationship between heterogeneous urban morphologies and urban air ventilation environment. a new method with cross-section areas, which takes into account the site-specific wind information measured at m height using the mm /calmet model simulation, was used to calculate the frontal area density (λ f ). using the site-specific wind information, the new calculation method of λ f focuses on the effects of the built environment to the wind field, which provides a spatially averaged understanding of wind permeability at the urban scale. in addition, the new calculation method of λ f considers the unique urban morphology of the podiums and towers in hong kong (i.e., many tall and slender buildings stand on large podiums), which shows that taking the urban morphology of podiums into consideration is important. therefore, the podium layer is defined within the urban canopy layer as shown in fig. . . the spatial characteristics of the large podiums provide much larger drag force on airflow nearer to the ground than the upper layers, and thus can greatly affect the wind environment at the pedestrian level. this study first correlates the pedestrian-level wind environment with λ f calculated at the podium layer, and then establishes an understanding of surface roughness and urban morphology based on ground coverage ratio (gcr), a term familiar to urban planners, with λ f to simplify the practical application of the understanding for professional use. the roughness properties of urban areas affect surface drag, scales and intensity of turbulence, wind speed, and the wind profile in urban areas (landsberg ) . the total drag on a roughness surface includes both a pressure drag (τ tp ) on the roughness elements and a skin drag (τ ts ) on the underlying surface (shao and yang ) . in this study, only the pressure drag is considered, since skin drag is relatively small and is not a factor that can be controlled at the urban scale. oke ( ) provided the logarithmic wind profile in a thermally neutral atmosphere, which is a semiempirical relationship that acts as a function of two aerodynamic characteristics: roughness length (z ) and the zero-plane displacement height (z d ). the reliable evaluation of such aerodynamic characteristics of urban areas is significant in depicting and predicting urban wind behaviors (grimmond and oke ) . currently, three methods can be used to estimate the surface roughness: davenport roughness classification (davenport et al. ) , morphologic, and micrometeorological methods (grimmond and oke ) . the davenport classification is a surface-type classification based on the assorted surface roughness values, using high-quality observations (davenport et al. ) , which covers a wide range of surface types. this method is not too helpful to describe urban permeability in highdensity cities, because most of the urban areas could only be described in class "skimming: city centre (z ≥ )". compared with the micrometeorological method, the morphometric method estimates the aerodynamic characteristics, such as z and z d , using empirical equations (lettau ; macdonald et al. ; raupach ; bottema ; kutzbach ) . grimmond and oke ( ) validated the empirical models by kutzbach, lettau, raupach, bottema, and macdonald. while reasonable relationships between z and frontal area index (λ f(θ) ) for low-and medium density forms have been found, there is a tendency of overestimation of z for higher density cases (bottema ) . grimmond and oke ( ) calculated λ f(θ) in the context of the urban morphology of north america cities. ratti et al. ( ) calculated λ f(θ) of wind directions in london, toulouse, berlin, and salt lake city. by incorporating a spatially continuous database on aerodynamic and morphometric characteristics, such as λ f(θ) , z , and z d , morphometric estimation methods can be helpful to urban planners and researchers in depicting the distribution of the roughness of the city. using bottema's model equation, gál and unger ( ) mapped z and z d to detect the ventilation paths in szeged. wong et al. ( ) mapped λ f(θ) to detect the air paths in the kowloon peninsula of hong kong. the frontal area index λ f(θ) is a function of wind direction of θ , which is an important parameter of the wind environment. the λ f(θ) in a particular wind direction of θ is defined (raupach ) as where a f represents the front areas of buildings that face the wind direction of θ , a t represents the total lot area, l y represents the mean breadth of the roughness elements that face the wind direction of θ , z h represents the mean building height, and ρ el represents the density (number) of buildings per unit area. λ f(θ) has been used widely by researchers in plant canopy and urban canopy communities to help quantify drag force. frontal area density, λ f(z,θ) , represents the density of λ f(θ) at a height increment of "z" : where a(θ ) proj( z) represents the area of building surfaces that approaches a wind direction of θ for a specified height increment " z" and a t represents the total lot area of the study area. compared with λ f(θ) , which is an average value that describes the urban morphology of the entire urban canopy, λ f(z,θ) represents a density that describes the urban morphology in the interested height band. burian et al. ( ) conducted frontal area density calculations in a height increment of m in phoenix city, and found that λ f(z,θ) is a function of land uses because the buildings in different land uses have different building morphologies. due to the morphological difference between the podium layer and building layer in hong kong, as shown in fig. . , the respective λ f(z,θ) of the layer is expected to be better than λ f(θ) in capturing and describing the complicated urban morphology in hong kong. using a high-resolution ( × m) three-dimensional building database with building height information and digital elevation model (dem), a self-developed program embedded as a vba script in the arcgis system was applied to calculate the frontal area density (λ f(z) ) at different height bands. λ f(z) accounts for the annual wind probability from main directions: where λ f(z,θ) represents the frontal area density at a particular wind direction (θ ), and can be calculated with eq. . . p θ represents annual wind probability at a particular direction (θ ). to identify the height of the podium and urban canopy layer in high-density urban areas of hong kong, a statistical study was conducted based on three-dimensional building database provided by the hong kong government. twenty-five urban areas have been sampled as shown in fig. . . mean and upper quartiles of the building and podium height at metropolitan and new town areas were calculated. according to the height distribution shown in fig. . , the urban canopy layer and podium layer at the metropolitan areas were identified as and m, respectively. in hong kong, the local topography and land-sea contrast impose significant influence on the wind direction in the immediate vicinity of the urban canopy layer, as shown in fig. . . therefore, to focus on the impact of building drag force on airflow, site-specific wind roses for annual non-typhoon winds at m height in directions were used to calculate the corresponding local values of λ f(z) . due to the complex topography of hong kong, the territory is divided into subareas, with various area-specific wind roses ( fig. . ). the data on site-specific wind roses were obtained from the fifth-generation ncar/psu mesoscale model (mm ) that incorporates the california meteorological (calmet) system (yim et al. ). mm is a limited-area, non-hydrostatic, and terrain-following mesoscale meteorological model. mm is designed to simulate mesoscale and regional-scale atmospheric circulation (dudhia ; yim et al. ). calmet is a diagnostic three-dimensional meteorological model that can interface with mm (scire et al. ) . the terrain in hong kong is complex; hence, the resolution used in mm simulations (typically down to km) cannot accurately capture the influence of topology characteristics on wind environment. therefore, calmet, a prognostic meteorological model capable of higher resolutions (down to m), was used. combining the data obtained from mm and the data obtained from an upper air sounding station, maintained by the hong kong observatory, in , the calmet model adjusts the estimated meteorological fields for the kinematic effects of terrain, slope flows, and terrain blocking effects to reflect the impact of a fine-scale terrain on resultant wind fields at m resolutions (yim et al. ) . in the calmet model simulation, the vertical coordinates were set with levels: , , , , , , , , , , , , , , , , , , , , , , , and , , , , , , , m (yim et al. ). in this chapter, λ f(z) was calculated in uniform grids. each grid represents a local roughness value. the calculating boundary (grid boundary) was so small that large commercial podiums and public transport stations can be larger than the grid cell and cross the grid boundaries, as shown in fig. . . values of λ f(z) for the cells at the middle of such large buildings may be underestimated. therefore, to estimate the local roughness of every grid when buildings cross grid cells, a new method of which the cross-section areas (red areas) were included in the frontal areas of the corresponding grid cell was proposed. compared with the map in polygon units (gál and unger ) , this new calculation with uniform grid allows an exploration of mapping with a better explanatory power. compared with the conventional calculation of λ f(z) , the nonexisting cross-section walls in the new calculation method could result in unrealistic surface roughness. however, such cross sections may be needed to avoid underestimation of the surface roughness at the high-density urban areas covered by large and closely packed buildings. thus, the correlations between the vr_ w,j and between the new method of λ f(z) with cross section and the traditional method of λ f(z) without cross section were compared. wind velocity ratios were obtained from wind tunnel tests for hong kong (hkpd ) . the values of vr_ w,j of study areas in wind tunnel tests were used as shown in fig. . . in the wind tunnel tests, test points were uniformly distributed in each study area. vr_ w,j for each test point has been described by (hkpd ) : where p i represents the annual probability of winds approaching the study area from the wind direction (i), and vr_ ,i,j represents the directional wind velocity ratio of the jth test point, the mean wind speed at m above the ground with respect to the reference at m (hkpd ). vr_ ,i,j is defined as (hkpd ): where v_ p,i,j represents the mean wind speed of the jth test point at the pedestrian level ( m above the ground) for wind direction (i), and v_ ,i represents the mean wind speed of the jth test point at m for wind direction (i). as emphasized in fig. . , if study areas in wind tunnel experiment were crossed by grids in the map, the average of λ f(z) for the study areas is calculated by where λ f i(z) represents the frontal area density in the ith grid, s i represents the area of the ith grid in the study area, and s t represents the area of the study. the λ f(z) in the podium layer (λ f( - m) ) that corresponds to the four grid sizes (resolutions), namely , , , and m, were calculated. the r values in table . illustrate that the new calculation method can be as accurately predict the wind velocity ratio as the traditional method without cross section. as expected, in accordance with values of the λ f( - m) including the unreal flow-confronting areas were larger than the ones calculated by the traditional method, and their correlations with vr_ w,j were similar (fig. . ) . on the other hand, the λ f( - m) values in the kowloon peninsula calculated by the two methods were compared. in high-density urban areas with large and closely packed buildings, the λ f( - m) values calculated by the traditional method without cross section were less than . ; some of them were even close to . this is a serious underestimation to the surface roughness. highlighted in fig. . , the new method with cross section in this chapter efficiently alleviates these underestimations by including the cross sections. based on the regression analysis result, following understandings can be stated: the new calculation method with cross sections can correctly predict the wind velocity ratio. furthermore, compared with the traditional method of calculating frontal area density, the new method can alleviate the underestimation of mapping urban surface roughness in high-density cities with large and closely packed buildings. as shown in table . , the values of r decrease along with the reduction of the grid sizes. choosing a larger grid size would have a positive effect on depicting the urban wind environment. however, r should not be the only criterion for selecting one grid size over another. for mapping roughness, the explanatory power of the map should not be totally traded off for the sake of the correctness of λ f(z) . after weighing the considerations, the resolution of × m was adopted in mapping urban permeability in hong kong. the skimming flow regime is normally found at the top of compact high-rise building areas (letzel et al. ) . similarly, due to the signature urban morphology of hong kong (i.e., high-density and tall buildings), the airflow above the top of the urban canopy layer may not easily enter the deep street canyons to benefit the wind environment at the pedestrian level. thus, the wind velocity ratio at the pedestrian level mostly depends on the wind permeability of the podium layer. a statistical study was conducted to validate the above assumption by comparing the sensitivities of vr_ w,j to changes of λ f(z) calculated at different layers. the cross-comparison results are plotted in fig. . a, b , which indicate that vr_ w,j has a higher correlation with λ f(z) at the podium layer ( - m). this illustrates that pedestrian-level wind speed depends on the urban morphology at the podium layer ( - m), rather than the building layer ( - m) or the whole canopy layer ( - m). this understanding is important to support the evidence-based urban planning and design in order to improve the pedestrian-level wind environment at high-density urban areas. compared with front area index, which was used to detect the air paths in hong kong (wong et al. ), λ f( - m) has been proven to be a better morphological factor in depicting the wind environment at the pedestrian level. as shown in fig. . a, the map of the frontal area density ( - m) depicts the local wind permeability at the podium layer in the kowloon peninsula and hong kong island. the continuous belts of high surface roughness on the northern coastline of the hong kong island and both sides of the kowloon peninsula, referred to as the wall effect of the kowloon peninsula, are evident (yim et al. ), whereas the wind permeability is very low. the maps of the frontal area density ( - m and - m) are also presented, as shown in fig. . b, c. these two maps are important for describing the wind permeability at the urban canyon layer. the turbulent mixing at the urban canyon layer is essential to improve urban air ventilation, alleviate air pollution, and dissipate the anthropogenic heat. compared with λ f(z) , ground coverage ratio (gcr) is a two-dimensional parameter commonly used by urban planners. gcr is defined as where a t represents the site area, a b represents the built area, w represents the average building width, and n represents the number of buildings. a statistical study was conducted to convert the frontal area density analysis to a practical design and planning tool; this was accomplished by investigating the relationship between λ f( - m) and gcr. local values of λ f( - m) and the gcr of the test areas ( × m) in the kowloon peninsula and the hong kong island were calculated. figure . shows a good linear relationship of both (r = . ). however, it should be noted the presence of outlier values of local surface roughness of large podiums and industrial buildings. equation . indicates the relationship between gcr and λ f(z) , which depends on k, the ratio between the averaged building width (w) and podium layer height, i.e. m. if the building width of urban areas is much larger than that of other areas with normal building morphology, the correlation between gcr and λ f( - m) in such areas can be significantly different from other areas. four examples of such sites, points a-d, are shown in figs. . and . . w ( . ) based on the above discussion, following understandings can be stated: ( ) there is a good linear relationship between λ f( - m) and gcr (r = . ) in most of the test points. for planners, using gcr to predict the wind environment at the pedestrian level is reasonable. compared with other traditional maps (gál and unger ; wong et al. ) , the proposed gcr map is more applicable to urban designers and planners due to its accessibility to the planners in the planning process. ( ) local values of some areas may deviate due to the extremely large building widths (large commercial podiums and industrial buildings). in this type of areas, the wind permeability cannot be predicted in gcr. however, the occurrence of this type of extreme examples is very small (approximately %). an urban-level wind environment of hong kong was mapped using gcr information in this section. kubota et al. ( ) and yoshie et al. ( ) conducted an earlier investigation on the relationship between gcr and the spatial average of wind veloc- coupled with the classification, the effect of different gcrs on the wind permeability can be identified. as shown in fig. . , three classification values are assigned: "class ", "class ", and "class ", which denote good, reasonable, and poor pedestrian wind performance, respectively. based on this classification, the map of wind performance at the podium layer in hong kong was generated as shown in fig. . . compared with the roughness map without classification, the map in this study is more intuitive; in addition, it allows urban planners to better modify building morphology in order to improve the urban air environment. such map can be the spatial reference for urban planners. after incorporating the respective site-specific wind roses, the areas with low wind permeability are depicted in fig. . . these areas block wind and worsen the wind environment at the pedestrian level of their leeward districts. potential air paths in the podium layer are also marked out in this map. the potential air paths would play an important role to improve the urban ventilation and environment quality by fig. . relationship between ground coverage ratio and spatial average of wind velocity ratios in mong kok and cities in japan (kubota et al. ; yoshie et al. , edited by authors). the number of the point pairs is fig. . map of wind permeability at the podium layer. the wind permeability at the podium level is depicted in the map: class : gcr = - %, class : gcr = - %, and class : gcr > %. based on the respective annual prevailing wind direction, the areas with low wind permeability are pointed out. these areas could block the natural ventilation and worsen the leeward districts' wind environment at the pedestrian level. potential air paths in the podium layer are also marked out in this map (for interpretation of the references to color in the text, the reader is referred to the electronic version of this book) podium designs as in the hkpsg bringing fresh airflow into the urban areas for the purpose of dissipating air pollutant and mitigating urban heat island intensity. the chapter has highlighted a number of important points that should be considered by city planners. first, one of the most significant factors is urban morphology, especially the podium layer, and its implication to the urban air ventilation environment. according to chap. , sects. - of the hong kong planning standards and guidelines (hkpsg) (hkpd ), a number of urban forms deemed to be conducive to the urban air ventilation environment have been proposed: … it is critical to increase the permeability of the urban fabric at the street levels. compact integrated developments and podium structures with full or large ground coverage on extensive sites typically found in hong kong are particularly impeding air movement and should be avoided where practicable. the following measures should be applied at the street level for large development/redevelopment sites particularly in the existing urban areas: • providing setback parallel to the prevailing wind; • designating non-building areas for sub-division of large land parcels; • creating voids in facades facing wind direction; and/or this chapter shows that the qualitative understanding of the podium structure, as mentioned in the hkpsg, is valid. in hong kong, some areas of high podium coverage can be identified. these areas require the most significant design, planning intervention and improvement. for building block disposition, the chapter has emphasized that city planners need to factor in the prevailing wind understanding to street layout and building disposition design as shown in fig. . . this understanding is in line with the concerns of the so-called "wall buildings", wherein a line of tall buildings screen the waterfront from the inland areas, thereby blocking the incoming urban air ventilation from the sea. based on the gcr information readily available to planners working on their gis system, the chapter has shown that planners can easily generate an urban wind permeability map, thereby enhancing the possibility to identify problem areas and, more importantly, to emphasize on potential air paths. the map also enables the interconnectivity of open spaces for urban air ventilation, and allows planners to take urban breezeways into account and design in accordance with the recommendations of the hkpsg (hkpd ) , as shown in fig. . : for better urban air ventilation in a dense, hot-humid city, breezeways along major prevailing wind directions and air paths intersecting the breezeways should be provided in order to allow effective air movements into the urban area to remove heat, gases and particulates and to improve the micro-climate of urban environment. breezeways should be created in forms of major open ways, such as principal roads, interlinked open spaces, amenity areas, non-building areas, building setbacks and low-rise building corridors, through the high-density/high-rise urban form. they should be aligned primarily along the prevailing wind direction routes, and as far as possible, to also preserve and funnel other natural airflows including sea and land breezes and valley winds, to the developed area. the disposition of amenity areas, building setbacks and non-building areas should be linked, and widening of the minor roads connecting to major roads should be planned in such a way to form ventilation corridors/air paths to further enhance wind penetration into inner parts of urbanized areas. for effective air dispersal, breezeways and air paths should be perpendicular or at an angle to each other and extend over a sufficiently long distance for continuity. breezeway and air path design as in the hkpsg using the urban wind permeability map of the territory, city planners can initially estimate the possible urban air ventilation environment of the urban areas with the average velocity ratios. adjusting the pedestrian-level wind speeds and predicting the bioclimatic conditions of the city have become possible. overall, the chapter has demonstrated a practical and reliable way for city planners to quickly obtain district-level urban air ventilation information for their board-based design works at the early stages. conceptually, avoiding wrong decisions that may be difficult to rectify later is, therefore, possible. aij guidebook for practical applications of cfd to pedestrian wind environment around buildings two decades of urban climate research: a review of turbulence, exchanges of energy and water, and the urban heat island effects of sea breeze on thermal environment as a measure against tokyo's urban heat island roughness parameters over regular rough surfaces: experimental requirements and model validation morphological analyses using d building databases estimating the roughness of cities and sheltered country a nonhydrostatic version of the penn state-ncar mesoscale model: validation tests and simulation of an atlantic cyclone and cold front recommendations of the cost action c on the use of cfd in predicting pedestrian wind environment detection of ventilation paths using high-resolution roughness parameter mapping in a large urban area aerodynamic properties of urban areas derived from analysis of surface form feasibility study for establishment of air ventilation assessment system. final report, the government of the hong kong special administrative region hong kong planning standards and guidelines. the government of the hong kong special administrative region hong kong planning department (hkpd) ( ) urban climatic map and standards for wind environment-feasibility study. working paper b: wind tunnel benchmarking studies, batch i. the government of the private office- - rental and price indices for grade a office in core districts. the government of the hong kong special administrative region institute for the environment (ienv) ( ) study of ventilation over hong kong a wind tunnel study of organised and turbulent air motions in urban street canyons numerical analysis of diffusion around a suspended expressway by a multi-scale cfd model wind tunnel tests on the relationship between building density and pedestrian-level wind velocity: development of guidelines for realizing acceptable wind environment in residential neighborhoods investigations of the modifications of wind profiles by artificially controlled surface roughness high resolution urban large-eddy simulation studies from street canyon to neighbourhood scale an improved method for the estimation of surface roughness of obstacle arrays cfd analysis of mesoscale climate in the greater tokyo area cfd analysis of wind climate from human scale to urban scale feasibility study for establishment of air ventilation assessment system (avas) policies and technical guidelines for urban planning of high-density cities-air ventilation assessment (ava) of hong kong wind tunnel simulation of flow and pollutant dispersal around the world trade centre site methods of investigating urban wind fields-physical models wind tunnel evaluation of pm samplers analysis of -d urban databases with respect to pollution dispersion for a number of european and american cities drag and drag partition on rough surfaces a user's guide for the calmet meteorological model (version ) a scheme for drag partition over rough surfaces aij guidelines for practical applications of cfd to pedestrian wind environment around buildings determination of the pedestrian wind environment in the city of ottawa using wind tunnel and field measurements a simple method for designation of urban ventilation corridors and its application to urban heat island analysis developing a high-resolution wind map for a complex terrain with a coupled mm /calmet system air ventilation impacts of the "wall effect" resulting from the alignment of high-rise buildings experimental study on air ventilation in a built-up area with closely-packed high-rise building key: cord- -l bd y y authors: so, winnie k.w.; chan, sophia s.c.; lee, angel c.k.; tiwari, agnes f.y. title: the knowledge level and precautionary measures taken by older adults during the sars outbreak in hong kong date: - - journal: international journal of nursing studies doi: . /j.ijnurstu. . . sha: doc_id: cord_uid: l bd y y abstract the study aims to examine the knowledge and the practice of the precautionary measures taken by older adults in hong kong against the outbreak of severe acute respiratory syndrome (sars). overall, more than half the participants responded correctly that droplet transmission is one of the main transmission routes of sars. those who received formal education demonstrated that they acquired greater knowledge of the sources and precautionary measures for sars. the types of precautionary measures used and the factors affecting their behaviours were discussed. the results of the study could help the health-care professionals develop appropriate health promotion and disease prevention programmes for older adults. severe acute respiratory syndrome (sars) has endangered populations worldwide (united states department of health and human service, centers for disease control and prevention, may ) . it has infected over people and caused more than deaths (hong kong sars expert committee (hksarsec), ) . in the early days of the outbreak, the source and mode of transmission were unknown (hksarsec, ) . older adults and the chronically ill were particularly susceptible to sars with a disproportionably large number of deaths occurring in these groups (hksars, ) . the emerging nature of sars has meant that there are few studies that have explored the perceptions of the hong kong community as they have passed through this crisis. the aim of the study is to describe the knowledge about sars and precautionary measures taken by older adults in hong kong. the world health organization (who) identified sars by name on march (hksarsec, . based on clinical and epidemiological data, and laboratory test, the who updated cases definition for surveillance of sars (who, may ) . clinical features of sars at the prodrome stage include: ( ) incubation period usually - days; ( ) fever (> c); ( ) chills and rigors; and ( ) other symptoms including headache, malaise, and myalgias may appear. at the later stage, respiratory symptoms including dry and non-productive cough, dyspnoea, and hypoxemia, may occur. chest radiographs may show pneumonic changes such as signs of infiltration and consolidation (who, n.d.) . it was determined that sars was mainly transmitted by respiratory droplets or by direct contact with an infected person's secretions (hong kong department of health (hkdh), ) . the sars epidemic in hong kong lasted almost months ( february- june ) . it gained to public awareness through the hong kong news media on february as an atypical pneumonia outbreak in a nearby province (guangdong) in southeastern mainland china. the outbreak began in hong kong on february , when an infected professor from mainland china (the index case) arrived with his wife; they stayed in a local hotel (hksarsec, ) . one day after his arrival, he was admitted to a hospital in hong kong with severe pneumonia and subsequently died. this hotel was later identified as the original hong kong site from which local and international (hanoi, singapore, and toronto) transmission occurred (hksar-sec, ) . the first hospital outbreak began on march when healthcare staff was reported on sick leave from a public hospital. outbreaks in other hospitals and a housing complex were also identified in april. (major events in the sars epidemic were summarized in table (hksarsec, ) . over the course of the outbreak, cases were reported including deaths. adults years of age or older were . % of the sars cases; however, . % of the deaths were within this age demographic and . % of the deaths in this population were persons with a history of chronic illnesses (the university of hong kong clinical trial centre (hkuctc), october ) . the aging population is growing in hong kong, as it is elsewhere. approximately . % (n= , ) of the total population is aged years old or above (hkcsd, october a) . this situation presents many challenges for health promotion and disease prevention activities, as many of the usual methods of disseminating health information are not appropriate for this population. in hong kong, older adults can receive primary health care in both public and private health sectors. in the public sector there are two choices, the elderly health services or the general outpatient clinics, both of which provide low-cost government subsidized services and both may be used concurrently. the department of health operates the elderly health services, which provides primary health care and health promotion for older adults once they enroll (hkdh, ) . the annual enrolment fee is hk$ (i.e. us$ . /ukd . ) and curative services cost hk$ (i.e., us$ . /ukd . ) per consultation. older adults may also go to the hospital authority's general outpatient clinic (gopc) for medical advice and treatment (hong kong hospital authority, n.d.) . at the gopc, the treatments including x-rays and laboratory cost hk$ (i.e. us$ . /ukd . ) and medications cost only hk$ (i.e. us$ . /ukd . ). if the patient cannot afford the payment for any of these services, the service charge is waived (hkdh, ; hong kong hospital authority, n.d.) . in the private sector, older adults can obtain primary and secondary health care from general practitioners (grant and yuen, ) . usually, fees are higher and charges vary, depending on the prestige of the physician and the location of the practice. medications and laboratory tests will be charged separately and clients are usually referred to other clinical facilities for these. older adults are able to buy prescribed medications, over-the-counter western medications and traditional chinese medicines/herbs at pharmacies. during mid-may, the hong kong government launched a campaign, which was led by the chief secretary, to keep the city healthy and clean. precautionary measures to prevent the transmission of sars related to personal hygiene and environmental sanitation were publicized daily in the media as a way to minimize the possibility of becoming infected with sars. the presence of functional impairments resulting from chronic illnesses or knowledge deficits due to low literacy levels may have influenced what older adults were able to do to comply with the recommended infection control measures. thus, great concern about older adults living alone was expressed by health care providers and in the media (kong, ) . older adults, who may not have reacted promptly and appropriately to the government's recommendations to prevent the transmission of sars, could have been at higher risk for contracting sars and potentially for presenting a higher risk of transmission to others. understanding older adults' knowledge level and adherence to the government's recommended precautionary measures to prevent transmission of sars is an essential step in being able to design similar promotion programmes for this population in the future. the research questions examined in this study were: ( ) what demographic variables influenced older adults' knowledge level, beliefs, and precautionary measures taken to prevent transmission of sars? ( ) what was the knowledge level of older adults about the transmission routes of sars? ( ) what were the beliefs of older adults about the possibility of becoming infected with sars? ( ) what precautionary measures were taken by older adults to prevent the transmission of sars? ( ) does the level of knowledge or beliefs about sars affect the types of precautionary measures used by older adults? a descriptive cross-sectional design was chosen. potential subjects were recruited from registered members of a government subsidized social service centre in the southern district of hong kong. this centre provides services such as home visits, social activities, and meals-on-wheels to the elder members of this working-class district. the eligibility criteria were: ( ) aged or above, ( ) able to speak in cantonese, ( ) no hearing impairment, and ( ) reachable by telephone. initially, registered members of the social service centre were contacted by telephone to determine their eligibility; older adults met the criteria. of these, people were willing to participate in the study (response rate= . %). an additional participants did not answer all the questions in the questionnaire and their data were not used in the analysis; therefore, the final sample size was . a survey instrument developed by leung et al. ( ) was used in this study. the original survey instrument composed of questions and is divided into five parts: ( ) self-perceived general health status; ( ) use of health services; ( ) possibility of contacting diagnosed sars cases; ( ) knowledge of transmission of sars and beliefs of contracting sars; ( ) precautionary measures taken to prevent transmission of sars; and ) sociodemographics. in this paper, the last three parts of the instrument were described as these parts were used for analysis and discussion. the other parts of the instrument have been described elsewhere (leung et al., ) . participants were asked to choose the main transmission routes of sars by answering ''yes/no'' or ''do not know'' for each of five possibilities. these five possible transmission routes reflected the current state of the knowledge about sars at the time of the survey (hkhwfb, april; june, ) . three questions aimed at determining the participants' beliefs about their likelihood of contracting sars were developed: ( ) how likely is it that you will become infected sars? ( ) how likely is it that you would survive if you were infected with sars? ( ) how confident are you in your doctor's ability to diagnose sars? each question required a choice from a -point likert scale (i.e., very likely= to very unlikely= ) and 'do not know' response. this section was composed of questions based on the widely publicized government recommended behaviours for preventing transmission of sars (hkhwfb, april, ) . the participants indicated how often they had implemented eight precautionary measures (e.g., wearing a face mask, covering your mouth when sneezing) during the past days. three of the questions asked were about hand washing behaviours (after sneezing/coughing, after touching possibly contaminated materials and the use of liquid soap instead of bar soap). the remaining three items asked about behaviours that are traditionally practised in hong kong, which required some alternation to avoid spread of sars. for example, sharing dishes at meals is common in the chinese culture. use serving spoon or chopsticks, rather than each individual each using their own chopsticks to take food from commonly shared dishes was recommended as a precautionary measure, but is not widely used (hkdh, november, ) . another common practice is to leave the toilet seat up while flushing; however, contact with urine or feaces is one of the transmission routes, so lowering the toilet cover before flushing may prevent contaminated water from splashing out (hkdh, november, ) . thirdly, a common serving towel is often used during meals and this practice may also transmit the disease. a -point likert scale ranging from (always) to (none) and a choice of ''do not know'' was added for the participants who did not know how to answer the questions. demographic data collected were used to examine whether the demographic variables were associated with the precautionary measures used in fighting against the infection of sars. the institutional review board of the university of hong kong/hospital authority hong kong west cluster approved this study. all the potential subjects were approached via telephone during the period between and may, to determine their eligibility. twenty-six nursing students from the university of hong kong were trained as interviewers. the training programme included: ( ) the purpose of the research including the research questions; ( ) how to conduct a telephone survey (e.g., communication techniques, how to obtain an informed consent, consistent use of the study procedure, and data recording) and ( ) assessment of their learning and ability to appropriately follow the study protocols were done by observation during role play. demographic variables were grouped by gender and chi squared test performed to determine if differences occurred due to gender. correct and incorrect responses on the knowledge questions about the transmission routes of sars were grouped by participants' education level and chi squared test performed. additional chi squared analysis was done on the remaining demographic characteristics. an alpha of . or less was considered significant. mean scores on the likert scales were calculated for each of the three beliefs about sars items and for each of the eight possible precautionary measures used to prevent transmission. the 'do not know' responses for these variables were not scored or included in the means. the mean scores and the total number of 'very often' responses to the precautionary measures and were then compared to the demographic variables to determine if demographics affected the level of precautionary behaviours undertaken by the participants. information about the demographic characteristics of the participants grouped by gender is presented in table . although . % (n= ) of the participants were parents, . % (n= ) did not live with the family and . % (n= ; male= ; female= ) lived alone. more than half of the participants ( . %) did not have any formal education. the majority of the participants ( . %) were born outside hong kong and most of them ( . %) were from mainland china. the percentage of participants' who gave the correct answers on the three main transmission routes of droplets, direct physical contact, and urine/feaces ranged from . % to . % (table ) . demographic characteristics were compared with the participants' answers of the main transmission routes of sars. significant differences were found between education level and droplet transmission (po . ), and between a history of visiting the mainland china within the past months and direct physical contact (po . ). participants' beliefs about the likelihood of contracting sars are presented in table . more than % of the participants reported that they were likely or very likely to contract sars; while, . % reported it was unlikely or very unlikely that they would survive if they contracted sars. overall, most participants had confidence in their doctor in terms of diagnosing sars. between % and % of participants gave the response 'do not know.' demographic characteristics were compared with the participants' beliefs about the likelihood of contracting sars and no significance was found. the frequency of taking precautionary measures varied among the participants (table ) . means for the hand-washing precautionary measures, covering the mouth while sneezing or coughing and wearing a mask were low, indicating that most participants often had practised these behaviours. in contrast, three precautionary measures (i.e., using serving spoons or chopsticks, lowering the toilet lid, and avoid using serving towels) that contradicted common cultural practices were not as frequently done. the participants who lived with their families were significantly more likely (t= . , po . ) to take preventive measures than those who did not live with their family. mean scores on eight precautionary measures were compared among demographic variables. significant differences were also found between: ( ) attaining education and the use of serving spoons or chopsticks at meals (po . ); ( ) place of birth and wear mask (po . ) and wash their hands after contact with possible contaminated materials (po . ); and ( ) living with the family and to cover their mouth while sneezing or coughing (po . ) and wash hands afterwards (po . ). participants who received formal education were more likely to use serving spoons or chopsticks at meals. for those born outside hong kong, were more likely to wear mask and note: missing values are: use serving chopsticks= ; wash hands once contacted contaminated materials= . a using serving spoon or chopsticks, rather than individuals each meal time. b lowering the toilet cover before flushing can prevent contaminated water from splashing out. c avoid using a common serving towel at meal time. wash hands after contact with possible contaminated materials. participants who lived with the family were more likely to cover their mouth while sneezing or coughing and wash hands afterwards. the perceptions of older adults in one district in hong kong about sars transmission routes, the likelihood of contracting and the precautionary measures taken to prevent transmission of sars were explored. the affect of demographic variables also was determined. significant differences occurred between the males and females in terms of educational attainment only, indicating that women were less educated than men. although no significance difference was found on other demographic variables, women were generally older, more likely to live without a partner, but to live with family members. more than half of the participants responded correctly by saying that transmission by droplets is one of the main transmission routes of sars. however, less than half of them provided correct answers for the rest of the questions. the timing and sequence of identifying the possible routes of sars transmission may have been a factor in whether or not the older adult acquired this information promptly. perhaps, participants had a better understanding of droplets transmission because it was the first route to be discovered and this occurred at an early stage of the outbreak (hksarsec, ) . it was later found that direct physical contact with sars patients and contact with urine or feaces was another route of transmission (hksarsec, ) . older adults usually take a longer time to acquire new knowledge and information (eliopoulos, ) . in addition, participants might not have received the information promptly due to a limited social network. another demographic variable that may have affected some participants' knowledge about transmission routes was the education level and travel to mainland china. when comparing the droplets transmission and education attainment, a significant difference occurred in the group of participants who answered incorrectly and who received less formal education. other significant differences were not found between knowledge and educational level. the participants' experience of traveling to and from the mainland china without contracting sars may be the reason why they did not recognize that direct physical contact was a major transmission route. knowledge about the transmission of sars may have affected participants' behaviours of taking precautionary measures. throughout the outbreak, the main route of transmission was a direct contact of the mucous membrane (eyes, nose, and mouth) with infectious respiratory droplets (weekly epidemiological record, october, ) . under certain circumstances, contact with urine or feaces was also reported as another route of transmission. the public awareness about the ''fecal droplet'' as a transmission route of sars was increased after the community outbreak in a private housing complex in hong kong (inadequate plumbing systems, september, ) . the who technical consultation concluded that inadequate plumbing systems also contributed to the spread of infectious diseases (inadequate plumbing systems, september, ) . therefore, it was essential to maintain good plumbing systems and take appropriate precautionary measures such as to lower the toilet lid before flushing. however, insufficient knowledge about transmission route of sars may have affected participants' awareness of adequate precautionary measures. this was evidenced by more than half of the participants reporting that they did not lower the toilet lid before flushing. although feacal droplet transmission has been less commonly identified as the main transmission route among the infected cases when compared with respiratory droplet transmission (the university of hong kong, n.d.) , insufficient knowledge among the older adults could have led to a higher risk of contracting sars. it is important for those who develop public health messages during crisis situations, such as the one sars presented in hong kong, to identify vulnerable populations that may not be literate and to target health promotion messages in appropriate methods, which have a high probability of reaching these populations. although the proportion of sars cases among the older adult population was low ( . %) compared with the young adult ( . %) and the middle-aged population ( . %), the fatality rate was the highest ( . %) in the older adult population (hkuctc, october, ) . the participants' responses may have reflected this reality, as many believed that it was unlikely that they would contract sars; however, they were less positive about their ability to survive if they did contract it. confidence in their physicians was expressed by over half of the participants. the rate of participants answering 'do not know' was high for all three questions in this section of the survey. this may reflect participants' uncertain knowledge level or their lack of understanding of the questions asked. these findings reinforce the importance of teaching older adults, who may be less easily reached by traditional methods due to the education level and social isolation, how to take precautionary measures and why they are important. the frequency of taking precautionary measures varied among the participants. interestingly, the means on hygiene measures related to hand washing and covering the face to prevent spread by droplets were low, indicating that these measures were practised by most participants; however, means on precautionary measures that required changing traditional cultural behaviours were much higher. most of the participants did not use serving chopsticks at mealtime and did not avoid using serving towels including their home and at restaurants. several possible explanations exist. older adults may find it harder to change ingrained cultural behaviours, they may not have known that these were important ways to prevent transmission or these behaviours may not relevant for them because they live alone; therefore, have meals alone. additional research is needed to clarify the lack of compliance to these measures. participants who were born outside hong kong may be more likely to go to mainland china or their place of birth. since they may have higher risk of infection when they travel around or their relatives and friends visit them, they may increase their alertness to take precautionary measures to prevent transmission of sars. family support has been shown to influence older people's health beliefs and self-care behaviours (hsu and gallinagh, ) . participants who lived with their families were more likely to use a higher number of the precautionary measures than those who did not live with their families. family support in terms of reinforcing and educating the participants to take preventive measures may influence the older adults' health behaviours. this finding supports previous findings in a similar hong kong population (hsu and gallinagh, ) . although no new case of sars has occurred since june (hkhwfb, june ) in hong kong, the possibility of another outbreak of sars still exists. health care professionals must understand how to deliver important health-related information to all segments of society, particularly when these types of public health crises arise. older adults, who are socially isolated or those who have low literacy rates, require health professionals to use alternative methods of dissemination of essential information; for example, inperson out-reach activities to district social services settings rather than relying on broadcast media. when acute disease outbreaks occur, a number of epidemiologic investigations are immediately undertaken; they provide essential information for managing and stopping the outbreak. however, smaller scale descriptive studies also need to be undertaken during these times to provide the needed insights concerning vulnerable populations (e.g., who is least likely to be knowledgeable) and culture-specific information (e.g., use of serving spoons/chopsticks). it is important that nurses become involved in this type of research because of the perspective they bring and that this type of research is conducted while people are still experiencing the crisis. these studies can provide nurses direction for planning and implementing appropriate health promotion and education programmes for older adults. several limitations were inherent in the methodology used in this study. the cross-sectional design provides information about one point in time. the convenience sample recruited from only one district in hong kong, limited the external validity of the findings among the older adult population. data were collected by phone interview, leaving the possibility that older adults who did not have phones may have different responses on study instruments. other variables such as social network that may have influenced older adults' beliefs or possibility of contracting sars were not included. a more representative and randomly chosen sample with the use of alternate data collection method (e.g. mailing, face-to-face interview) in future studies would improve the generalizability of findings. the telephone survey was used with content and face validity which was established by an expert panel; now that it has been used, some modifications could be made, which might clarify the participants' response so that fewer 'do not know' responses would occur. also, it is possible that the students collecting the data could have altered the study protocol causing some inaccuracy in the data unknown to the researchers. another factor that could have affected the responses given by participants was specific to hong kong culture. in chinese traditions, older adults do not feel comfortable discussing issues such as death and diseases. these traditions might hinder older adults in providing answers to some questions considered culturally sensitive (i.e., the possibility of contracting sars and the survival rate after contracting sars). the sars outbreak in hong kong presented unusual challenges for health care providers and citizens. before the outbreak had been contained, older adults' perceptions about sars and their preventative health behaviours were explored. this was the first systematic study to describe the knowledge, beliefs and sars precautions taken by the older adult population in hong kong. the participants' knowledge about the main transmission routes of sars was consistent with the precautionary measures they practised. nurses are in an ideal position to develop and implement studies of the learning needs of vulnerable sections of the population. gerontological nursing th edition the hong kong health care system population census: hong kong resident population aged and over by quinqennial age group and educational attainment (highest level attended) population census: population by age group elderly health services. retrieved health advice for people who have been in contact with sars patients severe acute respiratory syndrome (sars)-preventive measures welfare and food bureau (hkhwfb sars bulletin. retrieved welfare and food bureau (hkhwfb) sars bulletin. retrieved welfare and food bureau (hkhwfb) sars bulletin. retrieved fees and charges for public health services sars in hong kong: from experience to action. retrieved october hksars, ) fatality rate same as overseas the relationships between health beliefs and utilization of free health examinations in older people living in a community setting in taiwan inadequate plumbing systems likely contributed to sars transmission message from the president. the hong kong geriatrics society newsletter the impact of community psychological responses on outbreak control for severe acute respiratory syndrome in hong kong sars statistics for hong kong: specific updates for hong kong-age & gender specific fatality rate world health organization (who), may . case definitions for surveillance of severe acute respiratory syndrome (sars) the university of hong kong funded this study. the authors would like to thank the staff of the aberdeen kai fong welfare social center for their help during the process of subject recruitment; the nursing students of the university of hong kong for assistance during data collection; and dr. joan dodgson for assistance during preparation of the manuscript. key: cord- -r vf pqt authors: chun, jack title: a rawlsian model of land justice for hong kong: the controversy on the development of the north new territories date: - - journal: land and housing controversies in hong kong doi: . / - - - - _ sha: doc_id: cord_uid: r vf pqt i adopt a rawlsian model in analysing the challenge recently faced by the hong kong government regarding its governance of the land development. the challenge is illustrated with the stakeholders’ debates on three case studies: the brownfield sites, fanling golf course and the private agricultural land reserve. the rawlsian model adopted here aims to unfold the dialectics of the land controversy and identify the rawlsian solution. for this purpose, expounded are certain important rawlsian concepts, including the distinction between rationality and reasonableness. in conclusion, i argue that, while an immediate political reconciliation seems unlikely, the possibility of such a reconciliation is open in the long run if one grasps the crux of the stakeholders’ dialectics and recognizes the intricate interconnection of the overlapping consensus in the constitutional and institutional levels on the political conception of justice. in this chapter, a rawlsian model is adopted in analysing the dynamics between politics, governance and justice in the land controversy of hong kong. first, i outline the background of the land controversy. then, i introduce the concepts of reasonable pluralism, reconciliation and overlapping consensus, and explain how the rawlsian model is applicable to the general situation of hong kong. followed is an examination of three selected case studies of the land controversy in the north new territories, whereby the nature of the stakeholders' argumentative dialectics is illustrated. in addition, i further probe into the rawlsian distinctions between rationality and reasonableness and between the overlapping consensus in the constitutional and institutional levels on the conception of justice vis-a-vis his two principles of justice. the purpose is to unfold the crux of the land controversy and identify the rawlsian solution. to begin with, a public engagement on the land development in hong kong was officially embarked on april and ended on september . it was conducted by the task force on land supply (henceforth task force), formed in september by the commission of the hong kong government. in the engagement paper (land for hong kong, our home, our say!) , the task force discussed possible choices for the land development. their aim was to provide the public with the information and consultation on how to meet the urgent need for extra ha in land supply. in their final report (striving for multi-pronged land supply: report of the task force on land supply [henceforth report]), the task force claimed that the public engagement has "heighten[ed] society's awareness of issues of land resources; it also has stimulated heated discussions on the planning, allocation and rights over land. its impact on hong kong is therefore profound". the task force's observation was by no means an exaggeration. one of the reasons for the citizens' active engagement is the fact that hong kong, with a total area of km , has topped the world's housing market in price and become, for consecutive years up to , the least affordable city to buy a modest home (demographia ) . this was the background of the community's fervent participation in the public engagement and a source of the land controversy in hong kong. this public engagement, like others, faced a pressing question after the collection of the stakeholders' different opinions: that is, what follows? one has to appreciate the fact that the participants had diverse and often opposing motivations and expectations. gustafson and hertting ( ) rightly note that the success of a public engagement depends on the identification of the participants' different motives. in this connection, i will identify the source of the land controversy in hong kong in the dialectics of the stakeholders' disputes. now, among the options considered by the task force, each unavoidably touched on certain deep-seated interests represented by different sectors of the community. no matter what choices the government may finally make after the public engagement, it is clear that those negatively affected stakeholders would suspect that they have been treated unjustly and unfairly by the government. is there any way to settle the disputes among the stakeholders? can justice be ever served if a certain degree of arbitrariness in the space of reasons, as will be illustrated below, seems to play a role in the stakeholders' dialectics and the government's final decision? in short, is there land justice as such? and if there is, how should one make sense of it? confronting these questions, i will first introduce three conceptual tools found in rawls' theory of justice ( , , ) and then show how the rawlsian model is applicable to the general situation in hong kong. the first conceptual tool is rawls' idea of reasonable pluralism. this idea suggests that the divergence and discrepancy of people's moral, philosophical and religious beliefs are, as a matter of fact, bound to exist in a pluralistic society. it is a fact one should recognize and respect if a pluralistic society is to be sustained. at the convergence of chinese and the western values, hong kong has a history of pluralism in the cultural, social and religious dimensions. overall, different values and traditions are well respected by the citizens. this seems to fit in with the rawlsian notion of reasonable pluralism. in addition, for rawls, it is illegitimate for any government to use any coercive force in rigidly unifying people's diverse, comprehensive doctrines of beliefs into a single system. this sort of coercion would completely undermine the essence of reasonable pluralism. a corollary of this recognition is rawls' emphasis that the political conception of justice he advocates is not a comprehensive doctrine in competition with any other comprehensive doctrines. instead, it is a free-standing political conception that could belong to any reasonable comprehensive doctrine. what is the function of this free-standing political conception of justice? it concerns rawls' general view of political philosophy, which, in his later years, is assigned the mission of achieving a reconciliation among people who embrace opposing philosophical and moral doctrines in a pluralistic society. rawls ( , ) claims, [p] olitical philosophy may try to calm our frustration and rage against our society and its history by showing us the way in which its institutions, when properly understood from a philosophical point of view, are rational, and developed over time as they did to attain their present, rational form. this fits one of hegel's well-known sayings: "when we look at the world rationally, the world looks rationally back". reconciliation facilitates people to go along with each other, despite the discrepancy of their comprehensive doctrines of values. rawls' quotation of hegel's ( ) famous statement above is remarkable. the whole rawlsian project of reconciliation hinges on the way we see (or conceptualize) how justice be formed and served in society. to a large extent, it is a matter of what perspective (or, in hegel's terms, idea) one adopts in the dialectics on justice. now, there is a hope for reconciliation when and only when the conceptual confusion and misunderstanding regarding what counts as justice are cleared up, so that a rational order of the society can come to sight to all stakeholders. this sort of perspectival reconciliation is important for a pluralistic society, as is demonstrated in the case of hong kong below. to accomplish the reconciliation in a pluralistic society, according to rawls, stakeholders need to achieve an overlapping consensus on the political conception of justice. only after such an overlapping consensus on justice had been attempted and constructed could people ever attain their long-term reconciliation (in distinction from a temporary and fragile compromise or, in rawls' terms, modus vivendi) . this idea of overlapping consensus is an important conceptual tool in the context of reasonable pluralism. one might legitimately ask: how can a whole-hearted consensus on any political issue ever exist among all the stakeholders who basically have their interests in conflict (as represented by their incompatible comprehensive doctrines of philosophies and moral values)? long-term reconciliation and persistent reasonable pluralism sound almost like an oxymoron. for this reason, the search for the conceptual space where one can find the consensus of different stakeholders overlapping across different comprehensive doctrines becomes the most daunting task for any model that aims at a political reconciliation. i will explain how the rawlsian model helps construct this important conceptual space applicable to the land controversy at issue. at this point, replies to two possible objections are in order. first, one might question whether it is appropriate to apply the rawlsian model to a case like hong kong. the rawlsian model is seen to apply to a specific type of society rawls ( , - ) calls constitutional democracy. the objection questions the current status of hong kong as a constitutional democracy and casts doubt on the applicability of the rawlsian model. this objection is worth considering because an answer to it here paves the way towards the discussion of a possible solution to the land controversy by the end of the chapter. now, so far as the issue of constitutionality is concerned, one should note that, after the return of hong kong to china from the united kingdom in , the basic law has officially taken effect as the supreme law of hong kong, with which all the local, specific laws are required to square. according to the basic law, except for the military and foreign policies, hong kong government has the freedom to exercise its capitalist governance in line with the principle of "one country two systems" for years with no change to the lifestyles of people. and the basic law is mentioned in article of the constitution of the people's republic of china. in a derivative sense, hong kong is ruled under the basic law as its minuscule constitution within the rubrics of the grand chinese constitution. in this way, constitutionality is implemented in the legal system of hong kong in an indirect but real sense. concerning the idea of democracy, obviously, hong kong is not a politically democratic society so far as, for instance, the election of the chief executive is concerned. the right to the nomination and election of the chief executive is currently limited to the election committee, composed of members, who are either ex officio members or individuals in different professions elected by designated functional constituencies (or sub-sectors). currently, apart from the members of the election committee, the general public do not have the right to nominate or elect the chief executive. but it is fair to say that, according to article of the basic law, hong kong is entitled to evolve into a certain model of political democracy so far as the election of the chief executive is concerned. the article reads, the method for selecting the chief executive shall be specified in the light of the actual situation in the hong kong special administrative region and in accordance with the principle of gradual and orderly progress. the ultimate aim is the selection of the chief executive by universal suffrage upon nomination by a broadly representative nominating committee in accord with democratic procedures. it is difficult to foresee the exact trajectory or destination of the development of hong kong democracy. suffice it to note that the very possibility of developing hong kong into (something close to) a democracy and the fact that it is now in a process of morphing towards it as a political goal warrants the feasibility of the adoption of the rawlsian model. indeed, such a possibility and such a fact, when compounded, make the case of applicability even stronger, as the need for the guidance of a theoretical model in facilitating the process of democratization is normatively justifiable. the rawlsian model is one of such theoretical models. on the other hand, the adoption of rawls' theory might pose a different question. his thought experiment of the veil of ignorance in the original position, which lays down the foundation of his theory of justice, is controversial for its generality and abstractness. dworkin ( , - ) succinctly summarizes rawls' idea of original position in this way: it imagines a group of men and women who come together to form a social contract…. they are men and women with ordinary tastes, talents, ambitions, and convictions, but each is temporarily ignorant of these features of his own personality, and must agree upon a contract before his self-awareness returns…. rawls tries to show that if these men and women are rational, and act only in their own self-interest, they will choose his two principles of justice. in the original position, people are supposed to be rational and yet ignorant of their personal background and subjective inclinations. behind this so-called veil of ignorance, they collectively deliberate and attempt to reach a consensus on the principles of justice. one might challenge that rawls' theory as such could at most outline a hypothetical conception of justice. and, the objection goes, it could not address the actual problems of the real political world. exactly in this spirit, nagel ( ) raises an objection regarding the abstractness of the presuppositions of rawls' theory, in particular with regard to the original position. nagel argues, "there is a real question whether hypothetical choice under conditions of ignorance, as a representation of consent, can by itself provide a moral justification for outcomes that could not be unanimously agreed to if they were known in advance". that is, even if the rational agents in the original position chose the rawlsian principles of justice, it would not follow that, once they knew their personal backgrounds and abilities by stepping outside the veil of ignorance, as we do in reality, they might still stick to the same principles of justice that they agreed upon in the original position. on this score, the specific details of the land controversy in hong kong, entangled with the competing stakeholders' informed preferences and self-understanding, might be too mundane and contextualized to be suitable for the examination by such a general and abstract theory. what is the justification for the application of rawls' general theory of justice to the specific reality of hong kong? this is the question raised by the second objection. this objection might appear to be more legitimate to rawls' early than later works. after his switch to the practical consideration of reasonable pluralism, his theory is intended to address the actual conditions of the political reality. in his words ( , ), we view political philosophy as realistically utopian: that is, as probing the limits of practicable political possibility. our hope for the future of our society rests on the belief that the social world allows at least a decent political order, so that a reasonably just, though not perfect, democratic regime is possible. so we ask: what would a just democratic society be like under reasonably favourable but still possible historical conditions, conditions allowed by the laws and tendencies of the social world? what ideals and principles would such a society try to realize given the circumstances of justice in a democratic culture as we know them? the idea of political philosophy viewed as realistically utopian is important. it highlights the applicability intended by rawls to the concrete contexts of the political reality. the theory is no longer limited to the contemplation of merely idealistic, "perfect" cases of democracy. instead, a more down-to-earth approach to the "reasonably just, though not perfect, democratic regime" is adopted so that "reasonably favourable but still possible historical conditions" are addressed within the framework. rawls' appreciation of the "historical conditions" of society allows for the contextualization of his theory of justice by "probing the limits of practicable political possibility". the historical condition of hong kong, as delineated above, favours, where applicable, such a quest for the realistic application of a theoretical conception of justice. now, with the two possible objections briefly replied, i now move on to the deliberation of the further specifics of the land controversy, especially with regard to the development of the north new territories. i will further unravel the "space of reason" in the stakeholders' dialectics under the rawlsian analysis. the task force's engagement paper and report outlined the implementation schedules of the options in three categories: the short (within years), middle ( - years) and long term ( - years). now, given the urgent need for the land supply in hong kong, options that could help, to a certain extent, meet the demand within a short-term period have become highly important. three such options were identified by the task force from their final recommendations in their report. all of the three options belong to the north new territories. i will elaborate on the three options one by one. the task force's first and most recommended option is the development of the brownfield sites, where there are villages or business operations of commercial activities, such as open storage sites and container lorry parks. this option has received the widest support from the general community. the task force recommended the government to develop the brownfield sites that might feasibly provide new land supply up to ha (of which ha is for the short-term development, out of the total area of the scattered brownfield sites in ha). at the same time, the task force also realized the challenge for the government to step into this area because the force of resistance by the stakeholders there was strong. in as early as , the government had had confrontations with the villagers of the brownfield sites in wang chau by forcing them out from their village ( . ha in size). in addition, the government at that time failed to negotiate with the local kingpins for reclaiming their brownfield sites ( ha) with business operations. two problems with the large brownfield sites posed a serious challenge to the government: that is, first, how to move the business operations out from there to somewhere else in a cost-effective way, and, second, how to make a fair compensation to the property owners. the rawlsian model, discussed in the next section, is to examine the nature of this sort of question in terms of land justice: is it justice to force people and business operations out from there for the purpose of land development when there are other options available for meeting the target of seeking extra land supply? mutatis mutandis, this type of question is recurrent for all other options for the land development as well. in the report, the second top recommendation is to tap into the private agricultural land reserve owned by developers, again mostly found in the north new territories. in hong kong, a number of developers have kept the agricultural land in their reserve, the total area of which is estimated to be as much as ha. keeping such agricultural land in reserve, the private developers look for the opportunities to change the land use into private residential sites. in the past, developers on their own initiatives have applied for such an alternation of the land use. however, the success rate was low. in the past several years, only out of applications were successful. the real problem was that all those approved applications were only small and scattered pieces of land, totalling to ha only, which were not helpful enough to meet the demand for land supply. and such applications obviously lacked the proactive support from the government, as the developers only aimed at making profits for themselves. for this reason, the report recommended that the government take the lead and identify the suitable agricultural land currently owned by the developers. the task force called this second top option as the public-private partnership (ppp). however, objections to this option arise from two opposite directions. first, questions have been raised as to whether there are conflicts of interests in ppp, as the developers may receive favourable compensation from the government for returning their sizeable land and get further benefits when they are (naturally) chosen to be the developers of those areas into residential areas, including the private residential areas. the community's suspicion of the "collusion between the government and businesses" over the transfer of these sorts of benefits through ppp has already been noted by the task force in their report. on the other hand, since the target of the government is to build more public than private housing, another possible scenario is that the benefits gained by the developers may not be as high as they expect after their land is reclaimed. resistance from certain developers may happen and should not be neglected. the report suggested that the government could in this case apply the land resumption ordinance for "public purposes". according to the ordinance (land department ), "[t]he government may acquire private land by resumption for the implementation of public projects such as a road scheme, a public housing development, an urban renewal project, an open space, a drainage improvement project, a new market, a school or any item in the public works programme". if there is any dispute between the government and the stakeholders over the amount of compensation, it can be brought to the lands tribunal for the judicial review. obviously, this idea of ppp, if implemented, will engender a lot of controversies from the perspectives of different stakeholders. finally, the third option among the top priorities recommended by the report was the use of the sites under the private recreational leases. in hong kong, there are many private recreational leases by the government to the private clubs and organizations for a nominal annual rent. among the private recreational lease sites, the fanling golf course (fgc) has become the hottest topic. it is partly due to the large size of the site, which amounts to ha. another important factor concerns the timing. the expiry date of the government's lease of fgc is . it means that the government could promptly start the development of this area. this is possibly the fastest track one could ever find among all the options and recommendations by the task force. the report recommended that the government might first of all develop ha of fgc in order to ease up the pressing housing needs within a short period of time (i.e. less than years). the remaining ha could still be used for the international golf tournaments in the short term, allowing time for the consultant to examine how to develop the remaining area into the residential area. this proposed plan was divided into two phases because it would take time to deal with the conservation of heritage buildings and the preservation of endangered species of trees in the remaining ha of the site. debates by different stakeholders on this recommendation on fgc have been publicly staged. the antagonistic dialectics was fierce. for instance, the hong kong golf association sternly expressed their opposition to the development of fgc in an open statement published on the local newspapers. their rationale was that such development would be detrimental to the high ecological values of fgc. in response, the legislative council member andrew wan fired back, "our city is so small and our hunger for land supply is so severe -not only for housing, but also for public facilities such as hospitals and elderly care centres…. i find it rather clownish to hear that [the golf course should not be redeveloped because] it will affect the businesses of tycoons". however, the hong kong golf association continued their dialectics by arguing that "[r]eclaiming any part of fanling golf course would be a devastating and irreversible loss for hong kong". other arguments have been advanced by the stakeholders. the protection of the historical buildings and the conservation of precious trees there would inevitably reduce the size of the developable land of fgc. and the value of the development of the site would be significantly dwindled. furthermore, the large-scale construction of the transport and infrastructure would delay the completion of the project, in spite of its appearance to be the fastest possible option for the land development. on the other hand, for the public who have not visited fgc or had no interest in golf, the site was considered merely as a theme park solely for the rich that should be reclaimed for the public interests. yet, still, hundreds of the staff members of fgc opposed to the claw-back of the land because of a very simple and direct concern: they would lose their jobs. a further twist to the land controversy should be mentioned here. it was the government's announcement of their own preference, which was made even before the release of the task force's report. it was to build an artificial island close to the lantau island. this option was dubbed "lantau tomorrow vision" (hksar government ). immediately, the environmentalists and the general public attacked the government for a fake consultation. even afterwards the government claimed to accept all the recommendations by the task force, the public basically suspected that this was only the government's lip service, as it seemed to have its own agenda for the land development. in the face of the land controversy, the question of justice seems to be unavoidable. it is remarkable that, in their report ( , ), the task force considered the political topic of land justice as "outside their purview". they deliberately did not touch on this question. but, as i argued above, the concept of land justice is crucial for understanding the nature of the controversy and the possibility of a viable solution. the rawlsian model examined here is exactly to address the critical issue of land justice omitted by the task force in their report. to adopt the rawlsian model in examining the land justice, i will start with the two principles of justice as fairness. however, as will be clear below, my main concern is not the consideration of their theoretical justification but the examination of their practical implication for the "special psychologies" found in the stakeholders' dialectics. rawls' two principles of justice in the latest version ( , ) read: ( ) each person has the same indefeasible claim to a fully adequate scheme of equal basic liberties, which scheme is compatible with the same scheme of liberties for all; and ( ) social and economic inequalities are to satisfy two conditions: first, they are to be attached to offices and positions open to all under conditions of fair equality of opportunity; and second, they are to be to the greatest benefit of the least-advantaged members of society (the difference principle). i will discuss the second principle first and then return to the first principle. now, for the second principle, one may note that social and economic inequalities do take place in hong kong. for rawls, such inequalities are allowable in a just-and-fair society so long as the fair equality of opportunity is open to all in respect of the associated offices and positions. in the case of hong kong, one may find that offices and positions, when attached to certain forms of inequalities (such as the significant discrepancies in income between different types of jobs), are in general open to all citizens according to their abilities and qualifications. given this sort of openness in hong kong that, more or less, meets the first part of the second principle, i will narrow down the scope of my discussion to the second half of the principle, namely the difference principle, according to which social and economic inequalities are allowed only in the cases where they are to the greatest benefit of the least-advantaged members of society. for my purpose, it is important to differentiate theoretical from practical questions on the difference principle. sandel ( , ) , for instance, notes that the difference principle as adumbrated in the original position is counter-intuitive. he argues that, if one follows through rawls' position, the theoretical consequence is that people would strangely not be considered to deserve their dues (such as high salaries) on account of their personal talents and efforts expended. for rawls, personal talents and subjective propensities to make efforts in work are only natural endowments that randomly obtain in nature. they lie, in a sense, beyond one's control. rawls' position is that the justification for such dues should be linked up with nothing but the question whether they contribute to the greatest benefits of the least advantaged in society. this position, sandel contends, is problematic because it seems to disregard the fact that agents do deserve the moral recognition and dues for their talents cultivated and efforts made. on the other hand, sen ( , ) contends that the difference principle is problematic because it seems to infect rawls' position with an inconsistency. the alleged inconsistency is rawls' allowance for the particular idea of incentive (high salary, for instance, to a ceo) in the rational agents' deliberation in the original position. the idea of incentive would constitute a problem because it looked like a bribe to motivate people to work hard to the benefit of the least-advantaged people. rawls seemingly depends on this idea but he does not provide any justification why only this sort of bribe-based inequality be allowed while other inequalities are ruled out in the agents' abstract considerations in the original position. furthermore, cohen ( ) criticizes the difference principle because of its inability to safeguard against the theoretical possibility of substantial inequalities that might happen in society. that is, apparently, there would be no limit to the possible scale of inequality by dint of the difference principle. but all these general criticisms, important as they are, are worth mentioning only to clarify the very fact that, for my present purpose, they should be considered as side issues off the focal point i want to make regarding the difference principle. the point i want to make is not so much about the theoretical justifications as practical implications. sandel, sen and cohen are concerned with the justification for the difference principle in the original position. however, my current concern is about, vis-à-vis the application of the difference principle, how to interpret and channel away the stakeholders' misconception in their dialectics, specifically with regard to their perception of the government's possibly unequal treatment of them as a type of injustice in reality (i.e. outside the veil of ignorance). to analyse such a dialectical misconception, one may start by highlighting a typical mentality of the stakeholders from the aforementioned case studies. for instance, the employees of fgc opposed to the reclamation of the site because they would lose their jobs if such an option was implemented. underlying their opposition was their frustration as to why it would be they who should be unfairly chosen to make the sacrifice (of their jobs), while some other stakeholders apparently did not need to. the same mentality could be found in the villagers of wang chau who confronted the government and the kingpins who completely rejected the idea of clawing back their brownfield sites by the government in . when the stakeholders preferred to maintain their status quo, they would see the government to be unreasonable to select them as the target and force them to make the concession. in a similar vein, the public suspected the collusion between the government and the developers in the proposed ppp. from their perspective, the government should not unjustly allow a selected group of stakeholders (i.e. the developers) to unfairly take advantages of the situation when hong kong people collectively facing such a serious land problem. to come to grips with the stakeholders' mentality and the embedded confusion, it is necessary to further analyse the general tendency of their dialectics. people tend to identify inequality or unequal treatment by the government's policies with unfairness towards them. that is, when interpreted from within their perspectives, the stakeholders' resistance to (or, depending on the context, insistence on) certain choice of land to be selected and reclaimed by the government seems rational enough. in particular, when there is more than one possible choice to be selected for solving the problem with land supply, one tends, not without good rationales, to shift the onus to other parties so that one's own stakes need not be adversely affected. in other words, no matter how the government's land policy might be formulated in the aftermath of the public engagement, it would be (mistakenly) challenged as unfair in the eyes of many stakeholders because of the unavoidably unequal treatment of the different options, such as in the scenarios where some are chosen and some are not for the land development. indeed, unless a perfectly equal distribution of resources and responsibilities were possible in reality, there would always be perceivable arbitrariness to some degree in the government's policy in selecting the choices of land supply. to find an answer to this dialectical challenge, one has to go into the crucial distinction rawls ( , ) makes between rational and reasonable people. this is closely related to the question about the application of the difference principle to the land controversy at issue. now, people are rational if, crudely put, they act for their self-interests and, whenever possible, take advantage of their situations. on the other hand, people are considered as reasonable if they respect the fair terms of cooperation and the principles thus derived, even at the expense of their own interests. at some point, rational people, when taking advantages of their situations, could be acting unreasonably, that is, unfairly taking advantages of other stakeholders. another way of putting this distinction is to see the difference between private and public reason. in the individual level (private reason), one may adopt many legitimate rationales in chasing one's self-interests. yet, for the public reason, people reason not from their own private interests. instead, they reason from a collective viewpoint, which need not guarantee that the self-interests of any individuals, including their own, are protected against any interference when such an interference is deemed as necessary and legitimate, such as its being to the greatest benefits of the leastadvantaged members of society, as advocated by the difference principle. but how can one postulate reasonableness (public reason) from one's rational self-interests (private reason)? in reply to this question, rawls ( ) stresses the importance of the possession of a minimal moral sense by the rational agents in the original position in order for them to figure out the two principles of justice. in other words, the two principles of justice are already inclusive of both the rational and reasonable perspectives. being rational, the agent should be in some sense moral at the same time in the original position. this point is important because only by underscoring this minimal moral sense can rawls fully answer the challenge, such as the one raised by habermas ( ) , that merely from the self-interested rationality (private reason) one can never yield reasonableness (public reason) in one's judgement, which is required for the impartial agents in the original position to formulate the two principles of justice, especially the difference principle. however, rawls' answer only underpins his clarification of the situation in the original position. it does not explain how one may interpret the implication of the rationality/reasonableness distinction for the stakeholders in reality, which is my focal point here. now, applying the crucial distinction to their dialectics, the fundamental point is this: on pain of inconsistency, the stakeholders need to but typically fail to grasp the fact that, even if they have justifiable rationales in arguing why their vested interests need not (and from their perspectives, a fortiori, should not) be negatively affected, it does not follow that their position as such is a reasonable one. in other words, although stakeholders may have their rational justifications for disagreeing to the government's choices of the land supply, their position may well be only rational without being reasonable. as a result, the stakeholders might rationally resent the government (if they wanted to). but they could not reasonably disagree to it if the government's decision follows the public reason, aimed, for instance, at a fair distribution of resources in society to the greatest benefits of the least advantaged. in this light, the distinction at issue helps the stakeholders distinguish their rational resentment from reasonable judgement in their dialectics, which, i argue, are constantly confused by them. their rational resentment being fully justified (in the case where they have been adversely and unequally treated by the government), the stakeholders should also understand that it is fair for the government to ask them to follow the reasonable judgement (public reason) for the sake of others and at the expense of their self-interests. this recognition of the distinction between rationality and reasonableness is important on two counts. first, this is the demarcation between equality and fairness. for rawls, only fairness, not equality, counts as justice. that is why he allows inequalities in his principles of justice. however, many a stakeholder confuses the two (equality and fairness) as one concept, mixing up the justification for their rational resentment (at inequalities) with that for their reasonable judgement (in favour of fairness). in other words, when they found that they were inflicted with an unequal treatment, they typically inferred that this should be unfairness to them. the rawlsian model demonstrates that this inference is incorrect. second, the distinction is helpful for equipping the stakeholders to conceptually revamp their perspectives on what truly counts as justice. once the rationality/reasonableness distinction is incorporated into their perspectives (no matter what comprehensive doctrines they variously subscribe to), it can address their "special psychologies" regarding the extent to which they should put the collective interests prior to their self-interests when they pursue justice as fairness. an objection arises. why should the stakeholders' judgements be demanded to be reasonable in the first place if they are already rational? this is a legitimate question if the stakeholders' question is not to be begged. to answer the question, a regressive argument is in place here. in the first place, the stakeholders' rational resentment is legitimate enough and should be appreciated when their self-interests are unequally undermined by the government. but in order for them to criticize the government as being unfair or unjust to them, they need a consistent framework of justice, from which they can meaningfully mount their criticism. such a framework cannot be based merely on the stakeholders' private reasons or self-interests, as they are constantly in conflict with each other, clearly demonstrated by the land controversy. the framework, therefore, has to be established on the basis of collective interests, postulated by the public reason. and what the public reason yields is the reasonable judgement, which sees the public interests as logically prior to the private interests. in other words, reasonableness is indispensable because, as rawls holds, only when society collectively functions as a fair system of cooperation may one find justice (and derivatively injustice) therein. interpreted in this sense, reasonableness is indispensable for any stakeholders, including those who attempt to criticize the government as being unfair or unjust to them. this is the reason why reasonableness (public reason) would be regressively assumed in the dialectics of the stakeholders against the government, no matter what position they adopt in reality. to apply this regressive argument to the land controversy in hong kong, it means that the stakeholders, for instance, those of the north new territories, should agree to the espousal of the public reason along with the private reason side by side. and the public reason always takes precedence over the private reason in order to make possible the conceptual framework of justice. now, if the government exercises the public reason in their policies, the stakeholders should understand, normatively speaking, the need to square with the government's policy, despite the fact (which is the focal point i want to make in this chapter) that (a) this might go against their private reason or rational interests, and (b) a certain amount of inequality and arbitrariness of the choice of land supply inevitably remain in the government's final decision, as the perfect distribution of resources and responsibilities is impossible. my point, then, is boiled down to this, that, even when (a) and (b) occur, as they are bound to in reality, the final decision of the government can still be a just-and-fair re-distribution of the stakeholders' interests in the land controversy, provided the public reason is well exercised by the government. this is what the stakeholders cannot consistently reject. now, suppose the stakeholders recognized this distinction between rationality and reasonableness. wouldn't this already put them in the position where they could have an overlapping consensus on how the land justice be served? would the problem not, then, be solved? however, the rawlsian answer is much more sophisticated and, as one may say, realistic than this short-cut approach. for one thing, even recognizing such a distinction between rationality and reasonableness, the stakeholders need not be motivated to reach any overlapping consensus on the conception of justice. their rational resentment easily in reality supersedes their reasonable judgement, unless the stakeholders have a deep sense of justice cultivated and are willing to stick to it. such a cultivation, however, would depend on the existence of a well-ordered society, in which one finds oneself situated in the just-and-fair social and political institutions. in the actual world is a reciprocal relationship between the citizens' possession of the sense of justice and the existence of the just-and-fair social and political institutions. both would mutually depend on and reinforce each other through the reflective equilibrium. if one asks how this reciprocal relationship is initiated and sustained at all, the answer has to do with the motivation on the part of the stakeholders from a higher or more general level, which serves as a foundation that facilitates this reciprocal dependence and reinforcement in the particular institutional (policy) level, including that of the governmental policies on the land development. this higher level is found in the overlapping consensus, according to rawls, in the constitutional level. at this point, one has to return to the first principle of justice to complete the inquiry of this chapter. in hong kong, the basic law, the mandate of which comes from the chinese constitution, as noted above, serves as the minuscule constitution, given the special concept of one country two systems. now, in the discussion above, we have also noted an obvious omission in hong kong from the scheme of equal liberties that fall into the first principle of justice, that is the absence of hong kong people's liberty (and right) to vote for the election of the chief executive of hong kong. this particular lacuna of the scheme of liberties in the present poses serious problems with the formation of the overlapping consensus in the foundational or constitutional level. one typical question, engendered by this problem, is whether the government led by the chief executive and other politically appointed high-rank officials can be seen to have the mandate from hong kong people or serve as the embodiment of the people's collective interests in general so that it can genuinely represent people's public reason with the political accountability to them. the answer, at this stage, is clearly negative. without a clear mandate from the people or legitimate embodiment of the public reason as such, the overlapping consensus on the political conception of justice (here specifically referring to the first principle of justice) at the constitutional level (the basic law) cannot be completed. without the completion of this general foundation, people at most might maintain a modus vivendi in associating themselves with others who have in possession contrasting philosophical and moral preferences. a type of what rawls ( , ) calls "equilibrium point" would take place. that is, people may be, to a certain extent, willing to go along with others over the government's policies only for the sake of expedience, without their genuine support or commitment to them. this fragile compromise among the people could easily be disrupted should any critical events occur that are considered to undermine the integrity of their comprehensive doctrines. recent incidents, such as occupy central or the umbrella movement in , the large-scale confrontational incidents in society between the hong kong people and the government (and the police) over the proposed extradition bill in the second half of and the community's criticism of the government's policies in fighting against the epidemic spread of novel coronavirus in early , were but some of the never-ending manifestations of, among other things, the instability of the "equilibrium points" at work in hong kong. if one moves from the constitutional to the policy level, such as the level of the government's land policy, the same type of situation applies. in modelling the land controversy, one sees that a similar "equilibrium point" is at work. that is to say, even if the rawlsian distinction between rationality and reasonableness could be made known to all, people would, whenever possible, continue to pursue their rational stakes (vis-à-vis their private reason) at the expense of their reasonableness (and public reason). for, in their mind, the government, without the mandate or accountability to them, could not represent the public reason. if any stakeholders perceived their rational stakes jeopardized by any of the government's policies, it is likely that strong resistance would result. stakeholders would find it difficult to reach any reconciliation with any other stakeholders (including the government). crudely put, all this can be explained by the fact that the difference principle, as part of the second principle, can hardly be fully subscribed by the people because the first principle of justice (regarding people's equal liberties, such as their right to elect the chief executive of the government) is not yet fully established in the case of hong kong. people would continue to challenge the government (including their policies) on the ground that they could hardly represent their collective interests or be given their genuine mandate to implement justice as fairness. their challenge would be posed not only at the constitutional level but also, as a corollary, at the policy level. for this reason, rawls puts the rightful liberties of people, expressed in the first principle of justice, prior to the second principle as a theoretical construct more important and more fundamental. this delineation of the idea of overlapping consensus in the constitutional and institutional levels provides a crucial context in which one sees, first, how the clarification of the rationality/reasonableness distinction is necessary for the stakeholders to understand the possibility of their reconciliation with one another and, second, the fact that the stakeholders would likely achieve merely a compromise (modus vivendi) without the rationality/reasonableness distinction endorsed unless, and until, their overlapping consensus can be achieved at the constitutional level with their political liberties fully recognized. then, and only then, could their public reason be well formulated and represented in reality through the hong kong government. in conclusion, it is illuminating to cite a passage from rawls ( , ) , [p] olitical groups must enter the public forum of political discussion and appeal to other groups who do not share their comprehensive doctrine. this fact makes it rational for them to move out of the narrower circle of their own views and to develop political conceptions in terms of which they can explain and justify their preferred policies to a wider public so as to put together a majority. as they do this, they are led to formulate political conceptions of justice…. these conceptions provide the common currency of discussion and a deeper basis for explaining the meaning and implications of the principles and policies each group endorses [emphasis added]. the passage explains how the process of reflective equilibrium takes place when people are engaged in the institutional (policy) level with their collective deliberation on social and political issues. it is true that the cited passage is followed by a qualifying statement by rawls ( , ) that this sort of public forum may help only "once a constitutional consensus is in place". nevertheless, the mechanism of the reflective equilibrium in shaping a conception of justice, such as that of land justice in the institutional level, reveals a moral. namely, if the obstacle to the overlapping consensus in the institutional level (e.g. land justice) is to be removed, it has to have the corresponding one removed (first or simultaneously) at the constitutional level so that, for instance, hong kong people would have the genuine liberty to participate in the election of the chief executive, rendering the public reason to be legitimately represented by the government, which is then conceptualized to be accountable to the citizens. this emphasis on the connection of the overlapping consensus (and reconciliation) in the constitutional and the institutional levels, together with the cultivation of the requisite sense of justice among the stakeholders, is the political conception of justice that serves as the rawlsian long-term solution to the land controversy. to round out the discussion of this chapter, it is worth considering how the application of the rawlsian model to the land controversy addresses the main theme of the book, namely the interrelationship between politics, governance and justice. to begin with, rawls' notion of reasonable pluralism defines the dialectics of politics in a liberal society. in more than one way, politics concerns how stakeholders, including the government, dialectically navigate to a collective agreement through the pluralistic values of the society. at some points, the government's policies might result in the reallocation of social resources to different parties, engendering disputes among the latter. now, the government's attempt to seek the citizens' wide-ranging support for their governance, however, is bound to fail unless the citizens' sense of reasonableness has been cultivated so that, as stakeholders, they are equipped with a perspective where they can, conceptually speaking, exit from their parochialism and enter into the realm of public reason. nonetheless, the rawlsian model further asserts that this perspectival process of "in-and-out" in the citizens' deliberation would not happen if it were merely a political goal demanded by the government and imposed on the citizens for the sake of expedience. instead, this political goal has to be formulated with the citizens' support from bottom up as well. this requires, among other things, the mandate of the government and the legitimacy of their governance to be endorsed by the citizens. only in this way can the government function as the embodiment of the people's public reason even when its governance in some cases comes into a conflict of interests with these or those stakeholders. furthermore, this embodiment would not be completed unless the stakeholders had reached their overlapping consensus on a political conception of justice, whereby the governance of the government can be collectively understood as "just" and "fair" to them, again even in the cases where some parties' interests have been adversely affected. these triangular factorspolitics, governance and justice-are in this way dialectically interconnected with one another. really, to follow through the rawlsian model, justice is not something hammered out once and for all but dynamically constructed through a long, ongoing process of political negotiation, reconciliation and collective commitment to a political conception of justice in two levels. this moral ultimately allows one to see clearer the essence of the long-term (though not perfect) solution to the land controversy, while the original intents of the government and other stakeholders to look for a solution to the housing and land problem that has already exacerbated in hong kong, ironically, are something no one has ever doubted from first and last. if you're an egalitarian, how come you're so rich th annual demographia international housing affordability survey: media release reading rawls: critical studies on rawls understanding participatory governance: an analysis of participants' motives for participation phenomenology of spirit (a. v. miller, trans.) reconciliation through the public use of reason: remarks on john rawls's political liberalism election committee sub-sectors election chief executive's policy address land resumption and compensation in the urban area reconciliation arguments in john rawls' political philosophy. critical horizons reading rawls: critical studies on rawls' 'a theory of justice a theory of justice political liberalism justice as fairness: a restatement justice: what's the right thing to do empiricism and the philosophy of mind the idea of justice. london: penguin books. south china morning post, a acknowledgements i would like to thank yu kam por and betty yung for their incredible editorial patience and probing questions that have helped me turn the chapter into a less opaque one, though they will still disagree to many of the points i try to make. key: cord- -nsdhvc w authors: maki, dennis g. title: sars revisited: the challenge of controlling emerging infectious diseases at the local, regional, federal, and global levels date: - - journal: mayo clin proc doi: . / . . sha: doc_id: cord_uid: nsdhvc w nan i n , a blue-ribbon panel was commissioned by the institute of medicine of the national academy of sciences to advise the us government on emerging infectious diseases that posed a threat or potential threat to the health of people living in the united states and assist in the federal allocation of public health resources. , emerging infections were defined as infections caused by newly identified human pathogens-such as the legionella bacillus, the reemergence of previously controlled pathogens-such as measles, or the appearance of anti-infective resistancesuch as methicillin-resistant staphylococcus aureus, the incidence of which had increased significantly within the past decades or threatened to increase in the near future. since the outbreak of severe pneumonia in us veterans attending a convention at the bellevue-stratford hotel in , found months later to have been caused by a previously unknown and remarkably ubiquitous waterborne bacterium, legionella pneumophila, more than dozen human pathogens have been identified as agents of emerging infectious diseases in the united states (table ) . the most recent and perhaps most fearsome emerging infections are the appearance of west nile virus encephalitis in new york city in and its rapid spread westward ; inhalation anthrax, deriving from use of bacillus anthracis spores as a biologic weapon against the us civilian population in ; the global outbreak of severe acute respiratory syndrome (sars) in ; and the looming threat of pandemic influenza, especially global disease caused by the highly virulent avian subtype a (h n ). [ ] [ ] [ ] during the past months, mayo clinic proceedings has published reviews of diseases caused by of these emerging pathogens, west nile virus, the sars coronavirus (sars-cov), and avian influenza virus. efforts to better inform readers about the consequences of emerging infectious diseases continue in this issue of the proceedings, in which chiang et al report a study of cases of nosocomial sars acquired in taipei hospitals during . most of the patients, of whom were followed up for at least months, were health care workers, and because few had underlying diseases, all except survived; thus, this study provides some of the best data on the long-term effects of sars on the lung. the clinical features and natural history of sars encountered by chiang et al are similar to those reported in much larger cohorts. , all their patients had fever, and most had cough and dyspnea as well; however, % had diarrhea, and % had myalgias, indicative of the severe systemic immunoinflammatory response to this unique new human infection. , similarly, all their patients had lymphopenia, and most had elevated levels of lactate dehydrogenase, now well-defined surrogate laboratory markers for patients presenting with sars. , however, chiang et al also found that patients with a very high c-reactive protein or lactate dehydrogenase level at the outset were far more likely to have progression to a severe stage of disease requiring mechanical ventilatory support, information of value to clinicians who might be called on to manage patients with sars in the not-too-distant future. most interestingly, chiang et al show that whereas bilateral fibrotic changes were demonstrable by high-resolution computed tomographic imaging to months after the acute infection, most of the survivors showed near-normal spirometric lung volumes (forced vital capacity, forced expiratory volume in second), albeit one third with reduced diffusion capacity, but none required home oxygen. it is likely that most of these individuals will have recovery of normal lung function. these findings are very similar to the well-documented long-term pulmonary effects of garden-variety acute respiratory distress syndrome, stemming from overwhelming pneumonia, gastric aspiration, near drowning, trauma, pancreatitis, or systemic sepsis, in which most survivors have gratifying recovery of lung function in the early years after the acute episode. [ ] [ ] [ ] because sars is such a unique human viral infection and induces such an unusually severe systemic inflammatory response, , it will be important to closely follow survivors of severe sars for considerably longer to be certain that latently expressed progressive pulmonary fibrosis does not occur. between the first reports from the world health organization and the centers for disease control and prevention (cdc) that defined sars as a global threat in march , and control of the epidemic in southeast asia and north america months later, more than persons in the republic of china, hong kong, singapore, vietnam, taiwan, and canada became infected, and ( . %) died of the infection ; mortality exceeded % in patients older than years. , since the last communication on sars in the proceedings in april , there have been extraordinary advances in our understanding of the disease in terms of its pathogenesis, epidemiology, management, and control: editorial • like many of the emerging human pathogens such as borrelia burgdorferi (mice, deer), us hantavirus (mice), west nile virus (wild birds), variant creutzfeldt-jakob prions (cattle, potentially free-ranging cervids), monkeypox virus (exotic african rodents and primates, us prairie dogs), and avian influenza virus a (h n ) (edible birds), infection by sars-cov can legitimately be considered a zoonosis, and wild mammals formed the initial reservoir of the virus-sars-cov has been isolated from palm-top civets and raccoon dogs in the live animal markets in southern china, and purveyors of these animals commonly show asymptomatic sars-cov seropositivity. , the genomic evidence that sars-cov is an animal-human recombinant is compelling, [ ] [ ] [ ] [ ] and sars-cov appears to have had a biologic origin remarkably similar to the human influenza a viruses and human immunodeficiency virus. although the sars virus originated in animals and made the leap to humans, once established in the human population, the virus has spread rapidly person-toperson, and the major reservoir of human disease is humans in the early stage of infection, before they have been diagnosed as having the virus and placed in respiratory and barrier isolation. • elegant molecular epidemiology has traced the origins of sars-cov to foshan in guangdong province, southern china, from whence it spread to beijing, then to hong kong, and from hong kong to vietnam, singapore, and canada. , a -year-old chinese physician who traveled to hong kong on march , , where he spent only day, appears to have been the source of sars-cov that ultimately resulted in thousands of cases of sars in countries and continents. • sars-cov is a new human pathogen to most of the world. studies by the cdc have shown no serologic evidence of past infection in more than specimens from us residents collected long before the sars epidemic. • as a new human pathogen, there is, understandably, little if any natural immunity. virtually all persons who became infected by sars-cov became symptomatic, and studies of exposed health care workers show that less than % to % of those infected experience mild or subclinical infection. • sars spreads almost exclusively person-to-person by respiratory droplets, rarely by the airborne route ; the roles of contact or fecal-oral transmission are less clear but probably occur. , the puzzling large outbreak in amoy gardens in hong kong was recently traced to virus-laden aerosols generated from sewage, using sophisticated airflow-dynamic studies and computational fluid-zone modeling. however, whereas the outbreak in the amoy gardens complex represents distant airborne spread, distant spread is probably rare, as evidenced by the very low risk of infection in patients with no plausible face-to-face exposure to a patient with symptomatic sars, by the effectiveness of simple isolation measures in hospitals that did not have sophisticated negative-pressure air-controlled rooms with separate roofline exhaust, and by the relatively few secondary cases on commercial airliners. , [ ] [ ] [ ] in an investigation of flights in which an airliner transported or more symptomatic infected passengers, laboratory-confirmed cases of secondary sars were detected on flight, with the greatest risk to other passengers close to the index case (seated within rows, relative risk . ); on flight carrying symptomatic infected persons, possible transmission occurred to only other passenger, and no secondary illness was documented on another flight that carried person with early sars. • simple control measures, most importantly the use of a high-quality filtration mask, ideally an n- -type mask but even a surgical mask, combined with full-barrier precautions in a single room were highly effective in preventing spread to other patients and health care workers where it was most carefully studied, in hong kong, singapore, and canada. , , , • patients with early sars do not pose a risk to others until they become symptomatic and start to cough, but there is considerable variability in contagiousness, probably based on the quantity of virus in the respiratory secretions and the degree of coughing. very close proximity to an infected patient who is coughing heavily poses the greatest risk. it appears that most spread of the virus can be linked to "super spreaders," and most infected persons are probably not very contagious. , , [ ] [ ] [ ] [ ] understandably, the risk of acquisition of sars-cov is far higher in the hospital than in the community. , • the mean incubation period of sars is approximately days (range, - days) and is considerably longer than that for most other human respiratory viral infections, such as the common cold or influenza a, which permits case-contact investigations and quarantine of exposed contacts before those destined to become infected and contagious can spread the disease to others. • because so few persons develop clinical sars more than days after exposure, there is no need to extend quarantine of exposed persons beyond days. • fever is so ubiquitous in sars that monitoring the body temperature of quarantined contacts and health care workers caring for patients with sars is a sensitive and specific method for detection of early infection, especially for health care workers before they become symptomatic and contagious. all health care workers caring for patients with suspected or proven sars should be monitored to times daily; fever constitutes grounds for quarantine and diagnostic studies. , for personal use. mass reproduce only with permission from mayo clinic proceedings. • to control sars, early diagnosis is essential. clinical predictors for sars, based on study of large cohorts of patients in hong kong, suggest that fever, myalgia, malaise, an abnormal chest radiograph, lymphopenia, thrombocytopenia, and, most importantly, previous contact with a patient with sars are each associated with a greatly increased likelihood of sars. in contrast, in a newly symptomatic patient older than years or younger than years without a plausible face-to-face exposure who has a cough productive of sputum, abdominal pain, sore throat, rhinorrhea, or leukocytosis, sars is unlikely. • modern-day virology has shifted rapidly during the past decade, from tissue cultures and serologic techniques to detection of the viral genome in clinical specimens by nucleic acid amplification techniques, such as polymerase chain reaction (pcr) or, for rna viruses, reverse transcriptase-pcr (rt-pcr). highly sensitive and specific rt-pcr assays were developed in most of the countries afflicted by sars, most notably in hong kong, singapore, and canada, and were invaluable in early confirmation of sars-cov infection. the sensitivity of second-generation assays has been as high as % in the first days of illness. [ ] [ ] [ ] [ ] whereas a pcr assay developed at the cdc was given immediate investigational device exemption approval by the food and drug administration, no commercial pcr assay has yet been licensed for clinical use in the united states. if sars returns and spreads in the united states, it will be essential that reliable real-time pcr assays are available in us hospitals. public health laboratories are not clinical service laboratories and are unlikely to be able to meet the need if sars reappears on a major scale. private companies should be given access to clinical strains of sars-cov and, if available, clinical specimens from infected patients in order to test and validate commercial assays that hopefully will be as accurate as, perhaps more accurate than, the current cdc assay. • ribavirin was used empirically in many patients with sars in southeast asia with the impression that it was effective therapeutically; however, in vitro studies have shown that sars-cov is not susceptible to ribavirin at concentrations achievable clinically. hence, it is unlikely that the drug is active therapeutically. uncontrolled trials suggest that interferon alfa may be of benefit. , there are a number of compounds and antiviral drugs with in vitro activity against sars-cov, including interferon alfa, interferon beta, and glycyrrhizin (licorice-root extract). theoretical rna virus targets, such as protease inhibitors and fusion inhibitors, also need to be assessed for efficacy. if sars returns on a major scale, it will be essential that the efficacy of antiviral drugs, such as commercial interferons, is tested in randomized, double-blind trials. • whereas uncontrolled studies of treated cohorts in asia have suggested that using moderate doses of corticosteroids, to mg/kg of a prednisone-equivalent daily, at the first evidence of severe sars, specifically hypoxemia, may improve survival, , , corticosteroid therapy for sars has had serious adverse effects, and a single randomized trial of preemptive pulse corticosteroid therapy did not show benefit. if sars returns, it will also be essential that efforts are made to determine the efficacy of corticosteroids in a large prospective, randomized, doubleblind trial. • advancing age (> years) and coexisting illnessespecially diabetes or heart failure-greatly increase the likelihood of severe sars (requiring mechanical ventilatory support) and the risk of death. , , inexplicably, sars is usually very mild in children, who do not appear to be very contagious. also, maternal-fetal transmission does not appear to occur. • while coronaviruses are more resistant than most other respiratory viruses, sars-cov appears to be susceptible to the commercial microbicides used for surface decontamination in hospitals. • most importantly, outbreaks in hong kong, singapore, vietnam, canada, and elsewhere in the world were successfully controlled, but only by an intensive, coordinated effort in which the national public health authorities worked very closely with the regional public health agencies and, especially, hospital infection control officers and clinicians caring for patients with sars. [ ] [ ] [ ] [ ] the measures needed for control of sars are clear , , : ( ) earliest detection of cases, having at-risk individuals isolated and queried about their face-to-face contacts during the to days before the onset of illness; ( ) expeditious contact tracing, with uncompromising home quarantine for all contacts of suspect and proven cases; and ( ) stringent isolation of symptomatic suspect and proven cases, focusing most heavily on techniques to prevent droplet and airborne spread (eg, single negative-pressure rooms, ideally with separate roofline exhaust or filtration of outlet air; fit-tested high-filtration mask respirators and a face shield or goggles or a powered air-purifying system for all health care workers and others entering the room of the case, as well as the use of nonsterile gloves and gowns to prevent contact transmission). , the value of border screening and temperature monitoring of travelers is questionable. the resources needed to control an outbreak in a city or a country are huge. in north america, the toronto outbreak consisted of documented cases in hospitals. to control sars in toronto required home quarantine of more than , contacts and an informational hotline that handled more than , calls; the economic cost of the epidemic to the city and the city and provincial govern- ments was estimated at $ . billion (canadian). the longterm psychological impact of sars on patients, families, and health care workers was also very substantial. [ ] [ ] [ ] • efforts are now under way to test candidate sars vaccines. the national tragedy of september , , was followed by the most serious instance of bioterrorism involving the us civilian population in history, the spread of anthrax through the us mail. these events coincided with growing awareness that weaponized smallpox virus almost certainly yet exists in the world, with strong suspicion that the former soviet union, as well as countries that have sponsored international terrorism, such as iran and north korea, , retained smallpox virus as a potential weapon. the unthinkable has become plausible: weaponized smallpox virus in the hands of international terrorist groups. as a consequence, the federal government has undertaken major steps to greatly improve emergency preparedness at all levels, especially the capacity to respond to the use of biologic agents such as smallpox or anthrax as weapons against the civilian population as well as our military (table ) . , billions of dollars have been appropriated to improve the capacity of public health and clinical laboratories to reliably detect infectious agents that might represent biologic weapons; to improve the likelihood that emergency department physicians and all primary care providers could recognize anthrax, smallpox, and other infectious diseases that might denote bioterrorism; to establish and coordinate surveillance programs at the regional, state, and federal levels; and to train more than a million public protection personnel and greatly improve preparedness of the us hospitals. at my center, we have spent hundreds of person-hours identifying and retrofitting a bed patient-care unit for the potential accommodation of patients with smallpox or other highly contagious infections such as sars or pandemic influenza caused by a new strain. this local effort has focused on air control and negative-pressure isolation rooms, which have the capacity for supporting mechanical ventilation, and developing comprehensive guidelines for health care workers who would staff the unit. for the first time in our generation, there has been a major injection of federal dollars into the public health sector at the state, regional, and municipal levels. the challenge will be to provide sustained support, rather than a limited bolus of supplemental funding. hopefully all this effort will never be needed to control smallpox-or an even more terrifying engineered pathogen , -that might be used as a biologic weapon. if it is not, the effort will not have been wasted because it is likely that all the planning and resource allocation will prove invaluable for controlling the spread of natural emerging pathogens, such as sars-cov or a new strain of influenza virus, which are probably far more likely to pose a serious threat to human and animal health in the united states and worldwide. the greatest and most immediate threat is the longoverdue reappearance of pandemic influenza a. the leading and most dreaded candidate for the new pandemic subtype is avian influenza a (h n ), recently reviewed in this journal, which was first recognized in a large poultry outbreak in the live-animal markets of hong kong in , where the virus had acquired the capacity to spread from infected birds to humans and killed of infected persons. to control the outbreak, authorities killed nearly million chickens to eliminate the reservoir of infection. since that time there have been contained outbreaks of different subtypes of avian influenza-h n , h n , and h n -that have caused disease in poultry, with secondary infections reported among pigs and humans, but infrequent and mild human disease, such as conjunctivitis or mild influenza-like illness. there was only human death among cases in a large h n outbreak in the netherlands in . in january , a highly pathogenic strain of avian influenza a (h n ) was identified in south korea and spread rapidly over the succeeding months to other asian countries, cambodia, china and hong kong, indonesia, japan, laos, thailand, and vietnam. [ ] [ ] [ ] to date, there have been confirmed cases in humans, nearly all in children or young adults; ( %) have proved fatal. more than million edible birds have been slaughtered by governmental authorities. all species of domestic birds appear to be susceptible to the h n strain, which is probably transmissible to all species of wild birds, some of which migrate transcontinentally. the epidemic a (h n ) strain appears to be gaining virulence and was recently shown to have acquired the capacity of infecting mammalian species, domestic cats and wild felines within zoos and pigs. most alarmingly, there is growing evidence that person-to-person spread can occur, albeit yet rarely. the epidemic strain further shows high-level resistance to amantadine and rimantadine but is thus far susceptible to neuraminidase inhibitors, such as oseltamivir or zanamivir. if the strain acquires recombinant genes that facilitate human infection and person-to-person transmission, pandemic disease could prove more catastrophic than the great h n influenza epidemic of . even more concerning has been the challenge of developing an avian influenza vaccine. current influenza vaccines are unlikely to provide any protection against the new h n avian strain. the standard method for manufacturing influenza vaccines, growing the vaccine strain in chicken embryos, does not work because the avian a (h n ) strain is so virulent that it kills the embryo before there is sufficient virus to harvest. novel genetic techniques, under way in the united kingdom, will be needed to alter the strain's phenotypic features so that it can be grown in sufficient quantities in fertilized eggs and an effective vaccine can be constructed. vaccine manufacturers are understandably reluctant to make the investment to develop and manufacture a new vaccine, particularly in large quantities, when there is uncertainty whether the avian strain will indeed spread and necessitate administration of hundreds of millions of doses. similarly, the sole manufacturer of the only oral neuraminidase inhibitor likely to be effective against avian influenza (oseltamivir) has very limited production capacity, and less than million doses are currently available in us pharmaceutical stocks; the director of the cdc has stated that it would be desirable to have at least million doses available. in summary, cases of cutaneous or inhalation anthrax traced to domestic bioterrorism and the global sars outbreak represent ill winds that have blown considerable good. the greatly expanded us federal effort to improve national preparedness for bioterrorism has strengthened public health at every level, and whereas we are far from being able to consider the united states as fully prepared, we are better prepared than only years ago. the recent us epidemic of monkeypox, traced to importation of infected exotic african rodents and the burgeoning domestic trade in us prairie dogs, could be considered a live tabletop exercise-with a relatively innocuous pathogen-for the recognition and containment of smallpox. similarly, the global sars emergence has proved the enormous power of modern-day molecular biology to identify and characterize new pathogens, to detect clinical infections far more rapidly than in the past, and to quickly unravel the epidemiology of new infectious diseases-the scientific foundation for strategic control. the sars outbreak was contained only by unprecedented international cooperation under the leadership of the world health organization and successful coordination within the affected countries between national and regional public health agencies and health care providers. controlling the next influenza pandemic, especially if it is caused by a highly virulent subtype such as the current a (h n ) avian influenza virus, will require even greater international collaboration and vertical coordination in public health within the involved countries. it will also require an unprecedented commitment by the industrialized countries of the world to meet the needs of afflicted developing countries with limited public health resources. we are all in this together: it is in every country's self-interest to work collaboratively toward a common goal-the prevention of communicable disease and improvement of health of every citizen of the world. methicillin-resistant staphylococcus aureus: interstate spread of nosocomial infections with emergence of gentamicin-methicillin resistant strains update: investigation of bioterrorism-related anthrax and adverse events from antimicrobial prophylaxis world health organization. summary of probable sars cases with onset of illness from world health organization international avian influenza investigative team world health organization. cumulative number of confirmed human cases of avian influenza a (h n ) since west nile virus: epidemiology, clinical presentation, diagnosis, and prevention sars: epidemiology, clinical presentation, management, and infection control measures avian influenza: a new pandemic threat? eight-month prospective study of patients with hospital-acquired severe acute respiratory syndrome clinical features and short-term outcomes of patients with sars in the greater toronto area plasma inflammatory cytokines and chemokines in severe acute respiratory syndrome analysis of serum cytokines in patients with severe acute respiratory syndrome pulmonary function and health-related quality of life in a sample of long-term survivors of the acute respiratory distress syndrome canadian critical care trials group. one-year outcomes in survivors of the acute respiratory distress syndrome world health organization. severe acute respiratory syndrome (sars)-multi-country outbreak-update isolation and characterization of viruses related to the sars coronavirus from animals in southern china prevalence of igg antibody to sars-associated coronavirus in animal traders characterization of a novel coronavirus associated with severe acute respiratory syndrome the genome sequence of the sars-associated coronavirus mosaic evolution of the severe acute respiratory syndrome coronavirus phylogenomics and bioinformatics of sars-cov comparative full-length genome sequence analysis of sars coronavirus isolates and common mutations associated with putative origins of infection coronavirus genomic-sequence variations and the epidemiology of the severe acute respiratory syndrome severe acute respiratory syndrome (sars) in singapore: clinical features of index patient and initial contacts sars working group. a novel coronavirus associated with severe acute respiratory syndrome prevalence of asymptomatic infection by severe acute respiratory syndrome coronavirus in exposed healthcare workers [abstract cluster of severe acute respiratory syndrome cases among protected health care workers-toronto evidence of airborne transmission of the severe acute respiratory syndrome virus low risk of transmission of severe acute respiratory syndrome on airplanes: the singapore experience assessment of in-flight transmission of sars-results of contact tracing expert sars group of hospital authority. effectiveness of precautions against droplets and contact in prevention of nosocomial transmission of severe acute respiratory syndrome (sars) clinical progression and viral load in a community outbreak of coronavirusassociated sars pneumonia: a prospective study transmission dynamics of the etiological agent of sars in hong kong: impact of public health interventions transmission dynamics and control of severe acute respiratory syndrome modeling the sars epidemic epidemiological determinants of spread of causal agent of severe acute respiratory syndrome in hong kong nosocomial transmission of the severe acute respiratory syndrome (sars) [abstract abstract k- . . world health organization. severe acute respiratory syndrome (sars): who guidelines/recommendations/descriptions. available at: www.who.int/csr/sars/guidelines/en. accessibility verified hospital authority sars collaborative group. a clinical prediction rule for diagnosing severe acute respiratory syndrome in the emergency department molecular and diagnostic clinical virology in real time early diagnosis of sars coronavirus infection by real time rt-pcr detection of sars coronavirus in plasma by real-time rt-pcr detection of sars coronavirus in patients with suspected sars centers for disease control and prevention. severe acute respiratory syndrome (sars) and coronavirus testing--united states description and clinical treatment of an early outbreak of severe acute respiratory syndrome (sars) in guangzhou, pr china preliminary results on the potential therapeutic benefit of interferon alfacon- plus steroids in severe acute respiratory syndrome : . abstract k- e development of a standard treatment protocol for severe acute respiratory syndrome high-dose pulse versus nonpulse corticosteroid regimens in severe acute respiratory syndrome fatal aspergillosis in a patient with sars who was treated with corticosteroids the use of corticosteroids in sars clinical presentations and outcome of severe acute respiratory syndrome in children sattar sa. microbicides and the environmental control of nosocomial viral infections world health organization. a multicentre collaboration to investigate the cause of severe acute respiratory syndrome the international response to the outbreak of sars in public health measures to control the spread of the severe acute respiratory syndrome during the outbreak in toronto world health organization working group on prevention of international and community transmission of sars. public health interventions and sars spread the immediate psychological and occupational impact of the sars outbreak in a teaching hospital post-traumatic stress disorder and quality of life in patients diagnosed with sars [abstract severe acute respiratory syndrome-related psychiatric and posttraumatic morbidities and coping responses in medical staff within a primary health care setting in singapore canadian researchers testing sars vaccine in china the chilling true story of the largest covert biological weapons program in the world, told from the inside by the man who ran it the looming threat of bioterrorism available at: www.bt.cdc.gov/planning/tprstrategy/index.asp. accessibility verified october , . . public health security and bioterrorism preparedness and response act of expression of mouse interleukin- by a recombinant ectromelia virus suppresses cytolytic lymphocyte responses and overcomes genetic resistance to mousepox human influenza a h n virus related to a highly pathogenic avian influenza virus transmission of h n avian influenza a virus to human beings during a large outbreak in commercial poultry farms in the netherlands the evolution of h n influenza viruses in ducks in southern china avian h n influenza in cats. science [serial online thais suspect human spread of bird flu uk 'developing bird flu vaccine experts confront major obstacles in containing virulent bird flu hospital preparedness for severe acute respiratory syndrome in the united states: views from a national survey of infectious diseases consultants the detection of monkeypox in humans in the western hemisphere key: cord- -bs p ig authors: luk, andrea o. y.; ke, calvin; lau, eric s. h.; wu, hongjiang; goggins, william; ma, ronald c. w.; chow, elaine; kong, alice p. s.; so, wing-yee; chan, juliana c. n. title: secular trends in incidence of type and type diabetes in hong kong: a retrospective cohort study date: - - journal: plos med doi: . /journal.pmed. sha: doc_id: cord_uid: bs p ig background: there is very limited data on the time trend of diabetes incidence in asia. using population-level data, we report the secular trend of the incidence of type and type diabetes in hong kong between and . methods and findings: the hong kong diabetes surveillance database hosts clinical information on people with diabetes receiving care under the hong kong hospital authority, a statutory body that governs all public hospitals and clinics. sex-specific incidence rates were standardised to the age structure of the world health organization population. joinpoint regression analysis was used to describe incidence trends. a total of , cases of incident diabetes (type diabetes [n = , ]: mean age at diagnosis is . years, . % men; type diabetes [n = , ]: mean age at diagnosis is . years, . % men) were included. among people aged < years, incidence of both type and type diabetes increased. for type diabetes, the incidence increased from . ( % ci . – . ) to . ( % ci . – . ) per , person-years (average annual percentage change [aapc] . % [ % ci . – . ], p < . ) in boys and from . ( % ci . – . ) to . ( % ci . – . ) per , person-years (aapc . % [ % ci . – . ], p < . ] in girls; for type diabetes, the incidence increased from . ( % ci . – . ) to . ( % ci . – . ) per , person-years (aapc . % [ % ci . – . ], p < . ) in boys and from . ( % ci . – . ) to . ( % ci . – . ) per , person-years (aapc . % [ % ci . – . ], p < . ) in girls. in people aged to < years, incidence of type diabetes remained stable, but incidence of type diabetes increased over time from . ( % ci . – . ) to . ( % ci . – . ) per , person-years (aapc . % [ % ci . – . ], p < . ) in men and from . ( % ci . – . ) to . ( % ci . – . ) per , person-years (aapc . % [ % ci . – . ], p < . ) in women. in people aged to < years, incidence of type diabetes increased until / and then flattened. in people aged ≥ years, incidence was stable in men and declined in women after . no trend was identified in the incidence of type diabetes in people aged ≥ years. the present study is limited by its reliance on electronic medical records for identification of people with diabetes, which may result in incomplete capture of diabetes cases. the differentiation of type and type diabetes was based on an algorithm subject to potential misclassification. conclusions: there was an increase in incidence of type diabetes in people aged < years and stabilisation in people aged ≥ years. incidence of type diabetes continued to climb in people aged < years but remained constant in other age groups. the hong kong diabetes surveillance database hosts clinical information on people with diabetes receiving care under the hong kong hospital authority, a statutory body that governs all public hospitals and clinics. sex-specific incidence rates were standardised to the age structure of the world health organization population. joinpoint regression analysis was used to describe incidence trends. a total of , cases of incident diabetes (type diabetes [n = , ]: mean age at diagnosis is . years, . % men; type diabetes [n = , ]: mean age at diagnosis is . years, . % men) were included. among people aged < years, incidence of both type and type diabetes increased. for type diabetes, the incidence increased from . ( % ci . - . ) to . ( % ci . - . ) per , person-years (average annual percentage change [aapc] . % [ % ci . - . ], p < . ) in boys and from . ( % ci . - . ) to . ( % ci . - . ) per , person-years (aapc . % [ % ci . - . ], p < . ] in girls; for type diabetes, the incidence increased from . ( % ci . - . ) to . ( % ci . - . ) per , person-years (aapc . % [ % ci . - . ], p < . ) in boys and from . ( % ci . - . ) to , p < . ) in women. in people aged to < years, incidence of type diabetes increased until / and then flattened. in people aged � years, incidence was stable in men and declined in women after . no trend was identified in the incidence of type diabetes in people aged � years. the present study is limited by its reliance on electronic medical records for identification of people with diabetes, which may result in incomplete capture of diabetes cases. the differentiation of type and type diabetes was based on an algorithm subject to potential misclassification. there was an increase in incidence of type diabetes in people aged < years and stabilisation in people aged � years. incidence of type diabetes continued to climb in people aged < years but remained constant in other age groups. why was this study done? • diabetes affects over million people worldwide, and over half of the diabetes population comes from asian countries. • most studies on the burden of diabetes in asia reported the diabetes prevalence, i.e., the proportion of the population with disease, but few have considered diabetes incidence, i.e., the rate at which new cases have developed in the population. • knowledge of disease incidence informs how population exposure to risk factors has changed over time and is useful for projection of future prevalence. what did the researchers do and find? • we identified , people with new-onset type or type diabetes occurring between and in the electronic medical record system of the hong kong hospital authority. • we calculated the incidence rates of diabetes according to age categories and gender and analysed incidence trends over time. • we found that the incidence of both type and type diabetes increased in children and adolescents (aged < years). • incidence of type diabetes also increased in people aged to < years but was stable in people aged � years. type diabetes mellitus is a complex progressive disease of rapidly growing prevalence. the global prevalence of type diabetes is currently estimated at million and is projected to escalate to million over the next years [ ] . more than half of the world's population of those with type diabetes comes from asia, where rapid industrialisation and urbanisation have contributed to an obesogenic living environment and increasing rates of overweight and obesity [ ] . the majority of published population-based studies on the epidemiology of type and type diabetes in asia, including china, reported prevalence data, but few examined the incidence of diabetes [ , ] . although the prevalence informs the disease burden, the incidence reflects how population exposure to risk factors has changed over time, and these estimates are necessary for the accurate projection of future prevalence. importantly, disease incidence communicates to the health policy makers whether strategies to prevent diabetes have been effective. recently, quan and colleagues reported the incidence and prevalence of diabetes in hong kong and detected a decline in the incidence of diabetes over a -year period between and [ ] . however, diabetes types were not differentiated, and trends among the paediatric population were not explored. we accessed the territory-wide database hosted by the hong kong hospital authority (ha) and described the secular trends in incidence of type and type diabetes from to . hong kong is a special administrative region of people's republic of china and has a population of . million. the hong kong ha is a statutory body formed in that governs all public hospitals and government outpatient clinics in hong kong. because of the wide cost differential between public and private healthcare sectors, around % of the local residents receive care for chronic illnesses in the ha [ ] . a territory-wide electronic medical record system, adopted in , captures demographic information, diagnostic and procedure codes, laboratory results, and drug prescriptions of people attending public hospitals and clinics. the hong kong diabetes surveillance database (hkdsd) is a population-based cohort of people with diabetes in hong kong identified from the ha electronic medical record system between january and december . the analysis was not prespecified and was planned after obtaining and reviewing the content of the database. diabetes was ascertained based on one or more of the following qualifying criteria: ( ) glycated haemoglobin (hba c) � . % ( mmol/mol) in any one available hba c measurement [ ] ; ( ) fasting plasma glucose (fpg) � . mmol/l in any one available fpg measurement [ ] ; ( ) prescription of noninsulin antihyperglycaemic drugs and/or ( ) prescription of insulin for at least days continuously, with or without ( ) recording of the diagnostic code of diabetes based on the international classification of diseases, ninth revision (icd- ) code ; and/or ( ) recording of the diagnostic code of diabetes according to the revised edition of the international classification of primary care, world organization of national colleges, academics, and academic associations of general practitioners/family physicians code t or code t . to minimise misclassification of normal individuals as having diabetes, people who received diagnostic coding of diabetes but did not fulfil any of the laboratory or drug criteria throughout the observation are not considered. to avoid inclusion of women with gestational diabetes, we removed episodes occurring within months prior to or months after delivery (icd- codes - ) or occurring within months before or after any pregnancy-related encounter (icd- codes - ). however, women with subsequent episodes that met the criteria for diabetes occurring outside the context of any obstetric events would be included. the separation of diabetes types is not reliable based on coding alone in administrative databases. in the hkdsd, a small subset of people received icd- coding for both type and type diabetes. for the purpose of this analysis, we developed and validated an algorithm to delineate type from type diabetes using another database, the hong kong diabetes register (hkdr). in brief, the hkdr contains clinical information on people with physician-diagnosed diabetes who were referred to two public hospitals (prince of wales hospital and alice ho miu ling nethersole hospital) for assessment of diabetes complications. in the hkdr, diabetes subtype was determined by the referring physician and was independently confirmed with chart review by one of the investigators (ck) of the present study. type diabetes was defined as clinical presentation with diabetic ketoacidosis and/or continuous requirement of insulin within year of diagnosis. positivity for islet autoantibodies was not used to define autoimmune diabetes because antibodies were not routinely measured. of , patients in the hkdr, we excluded people with onset dates outside of january to december (n = , ) and those with missing data on diabetes subtype (n = ). of the remaining , people with newly diagnosed diabetes, type diabetes was confirmed in patients. the cohort was separated in a : ratio for derivation and validation of the algorithm, respectively. we considered icd- codes (type diabetes: icd- .x or .x , type diabetes: icd- .x or .x ) and types of insulin treatment in the algorithms, and we tested combinations for sensitivity, specificity, positive predictive value (ppv) and negative predictive value (npv) for identifying type diabetes. of these combinations, ratios of type to type diabetes codes � or prescription of a combination of short-and long-acting insulin and no noninsulin antihyperglycaemic treatment within the first year of diagnosis yielded the optimal sensitivity of . % ( % ci . - . ), specificity of . % ( % ci . - . ), ppv of . % ( % ci . - . ), and npv of . % ( % ci . - . ) in the hkdr for people aged < years in the validation cohort. the sensitivity and ppv of this algorithm for identifying type diabetes decreased to . %- . % and . %- . %, respectively, in people aged � years, which is expected because of the rarity of type diabetes at older ages. an incident case of diabetes was identified by the first occurrence of any episode fulfilling the definition of diabetes and at least years of diabetes-free observation prior. at least year of surveillance from the date of diagnosis was required to enable discrimination of type and type diabetes. thus, although the database includes cases of diabetes from january to december , incidence of diabetes was described from january to december . the date of diagnosis was the date to first fulfil the qualifying event. we estimated sexspecific annual incidence rates of type and type diabetes. the numerator was the number of incident cases of diabetes in the hkdsd in each calendar year, and the denominator was the estimated hong kong population of the previous year at midyear as reported by the local census and statistics department. calculated rates were expressed per , person-years. we reported age-standardised rates (using the age structure of the world health organization standard population) for the entire population and for subgroups by sex and age categories (< years, to < years, to < years, � years). we calculated the annual percentage change (apc) and the average apc (aapc) in incidence rates with % ci by sex and by age bands. joinpoint regression analysis was used to describe incidence trends over time. the optimal number of line segments that best fit the pattern was identified, and apcs were computed for the slope before and after each joinpoint using regression analysis. because of an observed irregularity in the number of new cases of type diabetes in , trend analysis including reporting of apc and aapc for both type and type diabetes (for consistency) was restricted to the period between january and december . in a sensitivity analysis, we conducted trend analysis for type diabetes using restricted cubic spline, which allowed for a more flexible fitting of the change in incidence rates, and results are presented in the supporting information. statistical significance was set at p-value of < . . analysis was performed using sas version . (cary, nc) and joinpoint regression program version . . . (national cancer institute, bethesda, md). of , people captured in the hkdsd, we excluded , people who had diabetes codes but did not fulfil other criteria of diabetes. we further excluded , cases of prevalent diabetes (episodes fulfilling diabetes between january and december ) and , cases of diabetes that occurred between january and december . the remaining , people with incident type or type diabetes occurring between and were included in the analysis (s fig, s table) . demographic and clinical characteristics of the cohort at diagnosis are detailed in s table. trends in incidence of type diabetes using the derived algorithm, , people with newly diagnosed diabetes were classified as having type diabetes, among whom ( . %) were aged < years and ( . %) and ( . %) were aged to < years and � years, respectively (s table) . age-standardised incidence of type diabetes increased from to in people aged < years in both sexes, from . ( % ci . - . ) to . ( % ci . - . ) per , person-years (aapc . % [ % ci . - . ], p < . ) in boys and from . ( % ci . - . ) to . ( % ci . - . ) per , person-years (aapc . % [ % ci . - . ], p < . ) in girls (table ) . broken down into narrower age bands, the incidence of type diabetes peaked in the age groups of - years in the female sex and - years in the male sex and declined with increasing age. among those aged to < years and � years, incidence of type diabetes remained stable over time (table ). sex differences in the risk of type diabetes were detected in the people aged < years but not in people aged � years. the rate ratio for type diabetes was . ( % ci . - . , p < . ) in girls compared with boys. among , incident cases of type diabetes, , ( . %) presented below years of age, , ( . %) presented in people aged to < years, and , presented ( . %) in people aged � years (s table) . the incidence rose with age and peaked in the age groups of - years in both men and women (fig ) . table, the majority ( . %) of the new episodes of type diabetes in was identified by first-time use of noninsulin antihyperglycaemic drugs alone, suggesting that these occurrences could be prevalent cases initially diagnosed and followed outside of ha and later presenting to ha for continuation of existing treatment. incident cases captured in or before were excluded from subsequent trend analysis. an increase in the incidence of type diabetes was observed in the < years and to < years age groups (table , fig a and b) . for people < years old, the age-standardised incidence of type diabetes increased from . ( % ci . - . ) to . ( % ci . - . ) per , person-years ( ) in men and women, respectively, for the entire period (p < . ). the sex disparity in incidence of type diabetes varied by age. for people < years old, the incidence was disproportionately higher in girls than in boys, with an overall rate ratio of . ( % ci . - . , p < . ). upon reaching young adulthood, the risk reversed, and men had higher incidence rates than women. in people aged to < years, we detected an initial increase in incidence followed by stabilisation in both sexes (table , fig c) . in men, the incidence of type diabetes increased from . ( % ci . using the territory-wide hkdsd, we conducted time trend analyses on the incidence of type and type diabetes in people in hong kong. between and , the incidence of type diabetes increased in people aged < years and to < years, increased and then stabilised in people aged to < years, and was unchanged in those aged � years. incidence of type diabetes continued to climb in people aged < years but remained constant in other age groups. although the incidence of type diabetes was the highest in those < years old, adult-onset type diabetes accounted for over two-thirds of newly diagnosed cases during the surveillance period. among those < years old, type diabetes contributed to more than half of the newly presented cases. the key strengths of this study were the use of population-level data through access to the electronic medical record system of the hong kong ha and its low susceptibility to selection bias. given the scarcity of population-level data on secular changes in diabetes incidence in asia, our results are timely in providing insights into the contemporary diabetes epidemic in this region. importantly, this study highlights the emerging problem of young-onset diabetes and calls for effective strategies to reduce modifiable risk factors for diabetes in this group. the multinational european diabetes (eurodiab) register, which included , incident cases of type diabetes in youth aged < years recorded between and , revealed regional differences in the trend of diabetes incidence [ ] . in areas with a high burden of type diabetes, such as the nordic countries, the united states, and australia, the incidence appeared to have stabilised over the past decade [ , , ] . conversely, the incidence of type diabetes has continued to rise in places of low disease prevalence, including east asia [ , ] . based on a registry of newly diagnosed cases of type diabetes in children aged < years in shanghai, zhao and colleagues observed an increase in incidence from . per , person-years in - to . per , person-years in - [ ] . from the - national health insurance service database containing physician-reported cases of type diabetes in children aged < years in south korea, kim and colleagues reported an incidence of . per , person-years, which was . -fold higher compared with the rate recorded in the earlier period of - [ ] . in the present study, we also detected an increase in the incidence of type diabetes in children and adolescents, and the increase occurred in both sexes. in hong kong, the incidence of type diabetes has not been determined since the last report decades ago. based on retrospective retrieval of paediatric cases of newly diagnosed diabetes between and , huen and colleagues recorded an incidence of . per , person-years for type diabetes in children aged < years in hong kong, which was considerably lower than our updated estimates of . - . per , person-years in a comparable age group [ ] . our observations, together with others' observations showing a similar rise in incidence, remain unexplained, although environmental factors, including obesity, nutrition, climate, and infection, have been implicated in the induction and acceleration of beta cell destruction [ ] . from surveys of hong kong school children, the prevalence of overweight or obesity rose from . % in the mid- s to . % in [ ] , and the prevalence was . % in primary school students and . % in secondary school students in the last estimation in [ ] . it is noteworthy that although the incidence was the highest in the paediatric population, adults aged > years accounted for two-thirds of the newly diagnosed cases in our database. in contrast to the rising trend of childhood-onset type diabetes, the incidence of adult-onset type diabetes has not increased. the growing number of young people acquiring type diabetes is a major health concern that is now seen globally. in the present study, % of incident cases of diabetes in people aged < years were type diabetes. the search for diabetes in youth registry, which systematically identified and followed youth with diabetes in the us, reported an annual increase of . % in the incidence of type diabetes in people aged < years between and , from . to . per , person-years in boys and from . to . per , person-years in girls [ ] . furthermore, the increase was larger in asians and pacific islanders (annual increase . %) than europeans (annual increase . %). similarly, wu and colleagues reported an increase in incidence from . to . per , person-years using a registry of newly diagnosed cases of young-onset diabetes presented between and in zhejiang, china [ ] . among those aged < years in hong kong, the average annual increase in incidence was . %- . %, and the last recorded crude incidence rates in were . and . per , person-years in boys and girl, respectively, which were lower than the us figures but higher than rates in china. similarly, we detected an increase in incidence of type diabetes in people aged to < years in both sexes. besides exposure to an increasingly obesogenic environment, intrauterine effects from gestational diabetes and/or maternal obesity and exposure to present-day endocrine disruptors may be responsible [ ] [ ] [ ] . it is also possible that the observed incidence trend of young-onset type diabetes was the result of people seeking medical attention earlier in their disease trajectory rather than an actual fall in the age of diabetes development. in this regard, people who would develop diabetes were diagnosed progressively earlier, thus removing people from the undiagnosed pool who would have otherwise presented at an older age. in people aged to < years, the incidence of type diabetes in both sexes initially increased and then flattened from / onward. in women aged � years, the incidence was stable until and declined thereafter, whereas in men aged � years, the incidence remained constant. the absence of a rise might reflect levelling off in exposure to risk factors. in hong kong, the prevalence of obesity has been stable in men and has declined in women since the mid- s [ , ] , which is attributable to a series of government-led health promotion initiatives targeting healthier lifestyles, such as the eatsmart programme and mandatory nutrition labelling during this period [ ] . women are generally more receptive to health information and ready to adopt a healthy lifestyle compared with men, which might in part account for the sex difference in trends of obesity and type diabetes [ ] . cigarette smoking is linked to the development of type diabetes [ ] . antismoking advertising campaigns and government policy to ban smoking in many public areas have resulted in a reduction in smoking rates over the past years, from . % in to . % in in hong kong [ ] . lastly, saturation effect could be an explanatory factor, wherein increased health awareness and improved screening efforts during earlier periods have captured most of the high-risk individuals, thus depleting the pool of undiagnosed type diabetes over time. in support of this, we observed a significant decline in hba c values at diagnosis of type diabetes from to , possibly reflecting proactive case finding and earlier detection. although screening programmes for diabetes have not been formally introduced in hong kong, governmental policies to enhance primary care, including the dissemination of a reference framework for diabetes care, could have an effect toward improving diabetes detection [ , ] . the increasing number of outpatient and inpatient attendances to public healthcare facilities over time also supports an increasing opportunity for diagnosing diabetes [ ] . limited studies indicated interethnic variation in the risks for type diabetes. alangh and colleagues reported -year secular trends in diabetes incidence in ontario, canada, and found that incidence increased moderately by % in the european population as compared with a -fold increase in the chinese population, in which the absolute incidence rate was twice that of europeans ( . versus . per , person-years) by [ ] . from contemporary studies, the ageand sex-adjusted diabetes incidence rates among adults were per , person-years in the united kingdom [ ] , per , person-years in sweden [ ] , and per , person-years in the us during the - period [ ] . over a comparable reporting period, the rates were , and per , person-years in men and women in our study, per , person-years in korea [ ] , and per , person-years in taiwan [ ] . differences in methods used to capture incident cases and diagnostic intensities would have influenced the estimates. allowing for these factors, available data, including those from the present study, suggest that the incidence of type diabetes may be higher in east asians than europeans. although chinese people are leaner than europeans, for the same bmi, the former have more visceral fat, greater insulin resistance, and more metabolic complications [ ] . moreover, low body weight is linked to poorer pancreatic beta cell reserve, and chinese people are more vulnerable to external factors, such as glucolipotoxicity, that trigger progressive decline in beta cell function [ ] . a sharp peak in the incidence of type diabetes was recorded in , and this could be connected to the severe acute respiratory syndrome epidemic in in hong kong [ ] . the excess of , new cases of type diabetes in compared with might be due to heightened health vigilance at the aftermath of the epidemic, which prompted increased doctor visits. the modest dip in the number of new cases in the ensuing years (from to ) compared with numbers between and could support earlier identification of cases during the transitory period, leaving fewer cases to be detected in subsequent years. the excess might also represent an injection of prevalent cases from the private sector to the public system in response to economic adversity. we acknowledge the following limitations in the study. an electronic medical record database was used to identify patients with diabetes, and we cannot exclude the possibility of incomplete capture. the data source included patients who attended only public healthcare facilities, and those receiving care in the private sector-who represent about % of the entire disease population-were not included. as such, the incidence rates as reported were likely underestimations of the actual figure by up to %. however, except for , there was no evidence that the ratio of medical care in private sector versus public sector has changed over time, and therefore, this is unlikely to affect assessment of incidence trends. two-hour plasma glucose by an oral glucose tolerance test (ogtt) was not included as one of the qualifying criteria for diabetes, which could also underestimate incidence rates, especially in the paediatric population in whom hba c alone has low sensitivity of diagnosing type diabetes [ ] . the categorisation of type and type diabetes was based on an algorithm rather than direct inspection of the clinical notes. although the algorithm was developed in an independent data set in which the diagnosis of type diabetes was verified by reviewing medical records, the absence of confirmatory tests such as anti-islet cell antibodies or c-peptide levels could lead to incorrect differentiation of type and type diabetes, affecting the accuracy of the algorithm. misclassifying type as type diabetes would significantly inflate the incidence of type diabetes, whereas the impact on incidence of type diabetes was probably minimal. the probability of incorrect grouping would be greater in older patients in whom the algorithm performed less well, and estimates of incidence of type diabetes in adults will require confirmation in other cohorts. because of limitations in details of the extracted information, we could not discern patients with other aetiologies of diabetes, such as maturity-onset diabetes of the young and secondary diabetes. owing to the asymptomatic nature of diabetes, diagnosis is often delayed. despite the good quality of the surveillance database, undiagnosed cases could not be captured, leading to underreporting of case burden. the recorded incidence rates were also sensitive to secular changes in people's health-seeking behaviour, screening practice, and prescription behaviour. in this report on the secular trend of the incidence of diabetes in hong kong, we revealed that the incidence of type diabetes increased in people aged < years and was stable in other age groups. the incidence of type diabetes also increased in people aged < years and accounted for over half of new cases of diabetes among people aged < years. in people aged � years, the incidence of type diabetes remained constant. these observations provide an impetus for scaling up measures to prevent development of diabetes in people at risk. (a) incidence trends of type diabetes in boys aged < years using restricted cubic spline. (b) incidence trends of type diabetes in men aged to < years using restricted cubic spline. (c) incidence trends of type diabetes in men aged to < years using restricted cubic spline. (d) incidence trends of type diabetes in men aged � years using restricted cubic spline. (e) incidence trends of type diabetes in girls aged < years using restricted cubic spline. (f) incidence trends of type diabetes in women aged to < years using restricted cubic spline. (g) incidence trends of type diabetes in women aged to < years using restricted cubic spline. (h) incidence trends of type diabetes in women aged � years using restricted cubic spline. international diabetes federation china noncommunicable disease surveillance group. prevalence and control of diabetes in chinese adults china national diabetes and metabolic disorders study group. prevalence of diabetes among men and women in china diabetes incidence and prevalence in hong kong, china during - thematic household survey report no. . hong kong sar: census and statistics department standards of medical care in diabetes- report of the expert committee on the diagnosis and classification of diabetes mellitus solté sz g; eurodiab study group. incidence trends for childhood type diabetes in europe during - and predicted new cases - : a multicentre prospective registration study norwegian childhood diabetes study group. incidence of type diabetes in norway among children aged - years between and : has the incidence stopped rising? results from the norwegian childhood diabetes registry regular peaks and troughs in the australian incidence of childhood type diabetes mellitus ( - ) a plateau in new onset type diabetes: incidence of pediatric diabetes in the united states military health system rapidly rising incidence of childhood type diabetes in chinese population: epidemiology in shanghai during - increasing incidence of type diabetes among korean children and adolescents: analysis of data from a nationwide registry in korea epidemiology of diabetes mellitus in children in hong kong: the hong kong childhood diabetes register the accelerator hypothesis: weight gain as the missing link between type i and type ii diabetes secular changes in height, weight and body mass index in hong kong children the government of the hong kong special administrative region search for diabetes in youth study. incidence trends of type and type diabetes among youths incidence and time trends of type diabetes mellitus in youth aged - years: a population-based registry in zhejiang, china diabetes and obesity in the offspring of pima indian women with diabetes during pregnancy glucose intolerance and cardiometabolic risk in adolescents exposed to maternal gestational diabetes: a -year follow-up study arsenic exposure and prevalence of type diabetes in us adults epidemiology of cardiovascular risk factors in hong kong worsening trend of central obesity despite stable or decline body mass index in hong kong chinese between and the government of the hong kong special administrative region. promoting health in hong kong: a strategic framework for prevention and control of non-communicable diseases a demographic perspective on gender, family and health in europe cigarette smoking is an independent risk factor for type diabetes: a four-year community-based prospective study tobacco and alcohol control office. department of health. the government of the hong kong special administrative region the government of the hong kong special administrative region. our partner for better health the government of the hong kong special administrative region. hong kong reference framework for diabetes care for adults in primary care settings. food and health bureau the government of the hong kong special administrative region rapid increase in diabetes incidence among chinese canadians between examining trends in type diabetes incidence, prevalence and mortality in the uk between incidence, prevalence and mortality of type diabetes requiring glucose-lowering treatment, and associated risks of cardiovascular complications: a nationwide study in sweden prevalence and incidence trends for diagnosed diabetes among adults aged to years trends in diabetes incidence in the last decade based on korean national health insurance claims data time trend analysis of the prevalence and incidence of diagnosed type diabetes among adults in taiwan from to : a populationbased study asians have lower body mass index but higher percent body fat than do whites: comparisons of anthropometric measurements diabetes in asia: epidemiology, risk factors, and pathophysiology a major outbreak of severe acute respiratory syndrome in hong kong utility of hemoglobin a( c) for diagnosing prediabetes and diabetes in obese children and adolescents we acknowledge the hong kong hospital authority for providing the data for research. key: cord- -vdiaexbw authors: kshetri, nir title: china date: journal: the statesman&#x ;s yearbook doi: . / - - - - _ sha: doc_id: cord_uid: vdiaexbw nan upon soviet assistance for economic development. a soviet-style five-year plan was put into action in , but the relationship with moscow was already showing signs of strain. by the end of the s the soviet union and china were rivals, spurring the chinese arms race. chinese research into atomic weapons culminated in the testing of the first chinese atomic bomb in . mao introduced rapid collectivization of farms in . the plan was not met with universal approval in the communist party but its implementation demonstrated mao's authority over the fortunes of the nation. in he launched the doctrine of letting a 'hundred flowers bloom', encouraging intellectual debate. however, the new freedoms took a turn mao did not expect and led to the questioning of the role of the party. strict controls were reimposed and free-thinkers were sent to work in the countryside to be 're-educated'. in may mao launched another ill-fated policy, the great leap forward. to promote rapid industrialization and socialism, the collectives were reorganized into larger units. neither the resources nor trained personnel were available for this huge task. backyard blast furnaces were set up to increase production of iron and steel. the great leap forward was a disaster. it is believed that m. died from famine. soviet advice against the project was ignored and a breakdown in relations with moscow came in , when soviet assistance was withdrawn. a rapprochement with the united states was achieved in the early s. having published his 'thoughts' in the 'little red book' (as it is known in the west) in , mao set the cultural revolution in motion. militant students were organized into groups of red guards to attack the party hierarchy. anyone perceived to lack enthusiasm for mao zedong thought was denounced. thousands died as the students lost control and the army was eventually called in to restore order. after mao's death in the gang of four, led by mao's widow jiang qing, attempted to seize power. these hard-liners were denounced and arrested. china effectively came under the control of deng xiaoping. deng pursued economic reform. the country was opened to western investment. special economic zones and 'open cities' were designated and private enterprise gradually returned. improved standards of living and a thriving economy increased expectations for civil liberties. the demand for political change climaxed in demonstrations by workers and students in april , following the funeral of communist party leader hu yaobang. in beijing where demonstrators peacefully occupied tiananmen square, they were evicted by the military who opened fire, killing more than , . hard-liners took control of the government, and martial law was imposed from may to jan. . since the leadership has concentrated on economic development. hong kong was returned to china from british rule in (for the background, see page ) and macao from portuguese rule in . the late s saw a cautious extension of civil liberties but chinese citizens are still denied most basic political rights. beijing was chosen for the olympic games. china's treatment of tibet came under the international spotlight in the build-up to the games, following violent protests in tibet's capital city, lhasa. the arrest by japan of a chinese trawler in disputed waters in marked the beginning of heightened tensions between the two nations in the east and south china seas. in china became the world's second largest national economy. in nov. the communist party congress selected xi jinping to succeed hu jintao as president from march . in sept. that year, former leadership hopeful bo xilai received a life sentence for corruption in one of china's highest-profile trials in decades. in oct. the government announced the end of the country's one-child policy. a month later, the presidents of china and taiwan met for talks-the first time that leaders from the respective territories had met since . on the economic front, gdp growth in was at its lowest level for a quarter of a century. china is bounded in the north by russia and mongolia; east by north korea, the yellow sea and the east china sea, with hong kong and macao as enclaves on the southeast coast; south by vietnam, laos, myanmar, india, bhutan and nepal; west by india, pakistan, afghanistan, tajikistan, kyrgyzstan and kazakhstan. the total area (including taiwan, hong kong and macao) is estimated at , , sq. km ( , , sq. miles). a law of feb. claimed the spratly, paracel and diaoyutasi islands. an agreement of sept. at prime ministerial level settled sino-indian border disputes which had first emerged in the war of . china's sixth national census was held on nov. . the total population of the provinces, autonomous regions and municipalities and of servicemen on the mainland was , , , ( , , females, representing Á %); density, per sq. km. china's population in represented % of the world's total population. the population rose by , , (or Á %) since the census in . there were , , urban residents, accounting for Á % of the population; compared to the census, the proportion of urban residents rose by Á % (reflecting the increasing migration from the countryside to towns and cities since the economy was opened up in the late s). population estimate, dec. : , , , . china has a fast-growing ageing population. whereas in only Á % of the population was aged or over and by this had increased to Á %, by it is expected to rise to Á %. long-term projections suggest that in as much as Á % of the population will be or older. the population is expected to peak at Á m. around and then begin to decline to such an extent that by around it will be back to the level. china is set to lose its status as the world's most populous country to india in about . the un gives a projected population for of , Á m. regulations restricting married couples to a single child, a policy enforced by compulsory abortions and economic sanctions, were widely ignored, and it was admitted in that the population target of , m. by would have to be revised to , m. from peasant couples were permitted a second child after four years if the first born was a girl, a measure to combat infanticide. in china started to implement a more widespread gradual relaxation of the one-child policy. in dec. the standing committee of the national people's congress (npc) approved a resolution allowing couples to have two children if either parent was an only child. the one-child policy was formally abandoned altogether from jan. . an estimated m. persons of chinese origin lived abroad in . a number of widely divergent varieties of chinese are spoken. the official 'modern standard chinese' is based on the dialect of north china. mandarin in one form or another is spoken by m. people in china, or around % of the population of mainland china. the wu language and its dialects has some m. native speakers and cantonese m. around m. people in china cannot speak mandarin. the ideographic writing system of 'characters' is uniform throughout the country, and has undergone systematic simplification. in a phonetic alphabet (pinyin) was devised to transcribe the characters, and in this was officially adopted for use in all texts in the roman alphabet. the previous transcription scheme (wade) is still used in taiwan and hong kong. mainland china is administratively divided into provinces, five autonomous regions (originally entirely or largely inhabited by ethnic minorities, though in some regions now outnumbered by han immigrants) and four government-controlled municipalities. these are in turn divided into prefectures, cities (of which are at prefecture level and at county level), , counties and urban districts. population of largest cities in : shanghai, Á m.; beijing (peking), Á m.; shenzhen, Á m.; guangzhou (canton), Á m.; tianjin, Á m.; dongguan, Á m.; wuhan, Á m.; foshan, Á m.; chengdu, Á m.; chongqing, Á m.; nanjing, Á m.; shenyang, Á m.; xian, Á m.; hangzhou, Á m.; haerbin, Á m.; suzhou, Á m.; dalian, Á m.; zhengzhou, Á m.; shantou, Á m.; jinan, Á m.; qingdao, Á m.; changchun, Á m.; kunming, Á m.; changsha, Á m.; taiyuan, Á m.; xiamen, Á m.; hefei, Á m.; urumqi (wulumuqi), Á m.; fuzhou, Á m.; shijiazhuang, Á m.; wuxi, Á m.; zhongshan, Á m.; wenzhou, Á m.; nanning, Á m.; ningbo, Á m.; guiyang, Á m.; lanzhou, Á m.; zibo, Á m.; changzhou, Á m.; nanchang, Á m.; xuzhou, Á m.; tangshan, Á m. china has ethnic groups. according to the census , , , people ( Á %) were of han nationality and , , ( Á %) were from national minorities (including zhuang, manchu, hui, miao, uighur, yi, tujia, mongolian and tibetan) . compared with the census, the han population increased by , , ( Á %), while the ethnic minorities increased by , , ( Á %). non-han populations predominate in the autonomous regions, most notably in tibet where tibetans account for around % of the population. chang tibet relations between tibet and china's central government have fluctuated over the question of tibetan independence. the borders were opened for trade with neighbouring countries in . in a buddhist seminary opened in lhasa, the regional capital, with students, and monasteries and shrines have since been renovated and reopened. there were some , monks and nuns in . in tibetan was reinstated as a 'major official language', competence in which is required of all administrative officials. in the then chinese president, jiang zemin, said he was prepared to meet the dalai lama provided he acknowledged chinese sovereignty over tibet and taiwan. in sept. direct contact between the exiled government and china was re-established after a nine-year gap. however, in march anti-chinese protests in lhasa ended in violence, with dozens reportedly killed by the chinese authorities, and in oct. that year the dalai lama stated he had lost hope of reaching agreement with china on tibet's status. in april he announced his retirement from active politics in favour of lobsang sangay, who had been elected to lead the tibetan government-in-exile. in july , shortly after us president obama had received the dalai lama in washington, china's soon-to-be president, xi jinping, pledged to 'smash' attempts to destabilize tibet. by feb. there had been over reported cases of self-immolation by tibetans protesting against chinese rule. the estimated population of tibet at the end of had risen to Á m. from Á m. at the census. the average population density was Á persons per sq. km in , although the majority of residents live in the southern and eastern parts of the region. birth rate (per , ), , Á ; death rate, Á . population of lhasa, the capital, in was , . about % of the population is engaged in the dominant industries of farming and animal husbandry. in the total sown area was , ha. output in : total grain crops, , tonnes; vegetables, , tonnes. in there were Á m. sheep and goats and Á m. cattle and yaks. tibet has over , mineral ore fields. mining, particularly of copper and gold, has expanded rapidly since when the railway came to tibet. cement production, : Á m. tonnes. electricity consumption totalled Á bn. kwh in . in there were , km of roads ( , km in most of china has a temperate climate but, with such a large country, extending far inland and embracing a wide range of latitude as well as containing large areas at high altitude, many parts experience extremes of climate, especially in winter. most rain falls during the summer, from may to sept., though amounts decrease inland. monthly average temperatures and annual rainfall ( ): beijing (peking), jan. Á f (- Á c), july Á f ( Á c). annual rainfall Á " ( mm). chongqing, jan. Á f ( Á c), july Á f ( Á c). annual rainfall Á " ( , mm). shanghai, jan. Á f ( Á c), july Á f ( Á c). annual rainfall Á " ( , mm). tianjin, jan. Á f (- Á c), july Á f ( Á c). annual rainfall Á " ( mm). on -in , and (currently in force) . the latter was partially amended in , , , and , endorsing the principles of a socialist market economy and of private ownership. the unicameral national people's congress is the highest organ of state power. usually meeting for one session a year, it can amend the constitution and nominally elects and has power to remove from office the highest officers of state. there are a maximum of , members of the congress, who are elected to serve five-year terms by municipal, regional and provincial people's congresses. - yang shangkun - jiang zemin - hu jintao -xi jinping prime ministers since . - zhou enlai - hua guofeng - zhao ziyang - li peng - zhu rongji wen jiabao -li keqiang elections of delegates to the th national people's congress were held between oct. and feb. by municipal, regional and provincial people's congresses. at its annual session in march the congress re-elected xi jinping as president and elected wang qishan as vice-president. president xi jinping succeeded hu jintao as president in march at the th national people's congress. tipped for the role since his appointment as secretary general of the chinese communist party (ccp) and chairman of the central military commission in nov. , xi pursued a strong style of authoritarian rule at home and a proactive and muscular foreign policy in his first term. in oct. the ccp gave him the title of 'core' leader, a significant honorific bracketing him with mao zedong and deng xiaoping among previous party figures although conferring no absolute powers. then, at its five-yearly congress in oct. , the party voted to enshrine his name and ideology in the chinese state constitution. he was subsequently re-elected in march and parliament also voted to abolish presidential term limits in a major shift from precedent. xi jinping was born on june in beijing, the son of one of the first generation of communist leaders. he joined the ccp in and, after graduating from tsinghua university in with a degree in chemical engineering, he became secretary to the vice-premier and secretary-general of the central military commission. xi became the zhengding county committee deputy secretary in hebei province in and the following year was promoted to secretary. in he was made deputy mayor of xiamen city, fujian province. having undertaken various party roles in the province, he became deputy governor of fujian in and governor a year later. in he moved to zhejiang province and made his first inroads into national politics when he was named a member of the th central committee. from - he was party secretary of fujian, overseeing economic growth averaging % a year and earning a reputation as an opponent of corruption. in march xi transferred to shanghai to take the role of party secretary following the dismissal of the incumbent on corruption charges. his appointment to such an important regional post was seen as a vote of confidence from the central government and he became a member of the politburo standing committee at the th party congress in oct. . he was also made a high-ranking member of the central secretariat. on march he was elected vice-president at the th national people's congress and took on a number of high profile portfolios including the presidency of the central party school. he was also beijing's senior representative for hong kong and ahead of his presidency, xi said little about his policy ambitions. there was hope abroad and at home that he would champion political and social reform and attempt to deal with corruption and a widening wealth gap between rich and poor and between urban and rural communities. he also faced the conundrum of how to provide adequate health care to a rapidly ageing population. in jan. the prospect of greater transparency and accountability under his leadership was undermined when the authorities began criminal proceedings against anti-corruption campaigners calling for public disclosure of officials' assets. this coincided with a report by a us investigative organization claiming that relatives of some of china's top political and military figures, including xi's brother-in-law, held secret offshore financial holdings. in other social and political affairs the ccp announced plans in nov. to ease china's one-child policy (which was subsequently abandoned following an announcement in oct. , with effect from ) and to abolish the system of 're-education through labour' camps, while a party plenum called-for the first time-for markets to play a 'decisive' role in the allocation of resources. meanwhile, in xi was confronted by domestic political opposition in the form of militant attacks by ethnic uighur separatists from xinjiang region and, from sept. that year, by widespread pro-democracy and autonomy protests in hong kong. on the economic front, china's previously frenetic annual rate of growth slowed markedly in , reflecting a slump in factory production and concerns over depressed oil prices, and again in to its lowest since . it also heralded severe stock market turbulence into despite emergency government measures, which had negative reverberations throughout the world economy. nevertheless, recognizing china's rise as a global economic power, the imf in nov. voted to add the yuan as the fifth member of its special drawing rights (sdr) currency basket alongside the us dollar, japanese yen, british pound and the euro. in foreign affairs, regional concerns over china's territorial and military intentions were raised in nov. by the government's declaration of a new 'air defence identification zone' over a swathe of the east china sea including disputed islands claimed by japan and south korea. there has also been friction, regionally and with the usa, over china's sovereignty claims and land reclamation operations on islands in the south china sea, although in july an international legal tribunal ruled in favour of a challenge by the philippines to china's sovereignty assertions-a verdict beijing vowed to ignore. further afield, xi has meanwhile undertaken numerous official visits abroad, as well as attending multilateral forums, for diplomatic, trading and investment purposes. and, while in singapore in nov. , xi and president ma ying-jeou of taiwan held the first direct talks between leaders of the two estranged governments since their split in . more recently, in xi aimed to extend china's economic and military co-operation with russia and also sought to defuse tensions with india over a simmering border dispute at an informal summit with prime minister narendra modi. meanwhile, friction with the usa escalated markedly over disputed trading and commercial practices, with both countries imposing punitive trade tariffs. li keqiang took office as premier of the state council, a role equivalent to prime minister, in march , succeeding wen jiabao. he was re-elected in march . li keqiang was born on july in dingyuan county, anhui province. following graduation from high school in , he joined the ccp and in he graduated in law from peking university, serving as head of the students' federation from - . he went on to earn a master's degree and doctorate in economics and headed the university's communist youth league of china (cylc) committee. over the following two decades he rose through the cylc ranks, joining the secretariat of its central committee in the s and serving as its first secretary in the s. at this time he built up his power base and forged close ties with hu jintao, a fellow cylc committee member and future chinese president. in li became deputy party secretary for henan province and a year later was appointed henan's governor. in dec. he was named party secretary for liaoning province where he spearheaded a major coastal infrastructure project, the ' points and one line' highway development. in this template was adopted at the national level to rejuvenate industrial northeast china. he also oversaw the rehousing of Á m. shanty-town residents into new apartment blocks over a three-year period. li advanced to national level politics when he was elected to the politburo standing committee in oct. . he was appointed vice-premier of the state council in march , leading a medical reform programme aimed at creating an accessible public health care service. he also chaired an affordable housing programme and introduced tax reform plans. in nov. li was re-elected as a member of the politburo standing committee and on march became premier of the state council at the th national people's congress. regarded as the steward of the chinese economy, li has aimed to focus on securing china's long-term expansion and on the further provision of basic national health care, affordable housing, employment growth, regional development and cleaner energy. however, global confidence in china's economy has been shaken since as the country's growth momentum has slowed amid apparent policy differences and blunders, prompting rumours that li was being increasingly sidelined in the governing hierarchy. he was nevertheless re-elected to the politburo standing committee in oct. and to the premiership in march . having sought assurances that a recently revised us-mexico-canada trade agreement would not stop canada from signing deals with other countries, li met with canadian prime minister justin trudeau in nov. at an international summit in singapore with the aim of pursuing negotiations on a bilateral free trade pact. the chinese president is chairman of the state and party's military commissions. china is divided into seven military regions. the military commander also commands the air, naval and civilian militia forces assigned to each region. china's armed forces (pla: 'people's liberation army'), totalling nearly Á m. in including the paramilitary people's armed police (pap) and Á m. excluding the pap, are the largest of any country. however, active armed personnel numbers have halved since . moreover, in president xi laid out plans to reform the army structure-replacing an organization based on seven regions with one based on five 'theatre commands'-and reduce the number of military personnel by a further , . conscription is compulsory, but for organizational reasons, is selective: only some % of potential recruits are called up. service is for two years. a military academy to train senior officers in modern warfare was established in . defence expenditure in was us$ , m. (equivalent to us$ per capita). china's military spending more than trebled between and . defence spending in represented Á % of gdp, although the share has actually declined since . only the usa spent more on defence in , but china's defence expenditure totalled around a fifth of that of the usa. in march it was announced that the defence budget would rise by Á % to us$ bn. following increases of Á %, Á % and Á % in the previous three years. china is the world's third largest exporter of arms after the usa and russia, with Á % of the global major weapons total over the period - . in the period - it had only been the eighth largest exporter. as at may china had , personnel serving in un peacekeeping operations (the largest contingent of any of the five permanent members of the un security council and more than the other four combined). having carried out its first test in , there have been tests in all at lop nur, in xinjiang (the last in ). the nuclear arsenal consisted of approximately operational warheads in jan. according to the stockholm international peace research institute. china has been helping pakistan with its nuclear efforts. the army (the pla groundforce) is divided into main and local forces. main forces, administered by the seven military regions in which they are stationed, but commanded by the ministry of defence, are available for operation anywhere and are better equipped. local forces concentrate on the defence of their own regions. ground forces are divided into infantry, armour, artillery, air defence, aviation, engineering, chemical defence and communications service arms. there are also specialized units for electronic counter-measures, reconnaissance and mapping. in there were group armies covering seven military regions. they included: armoured divisions and brigades; mechanized infantry divisions, brigades and regiments; motorized infantry divisions and brigades; nine special operations units; artillery divisions and brigades; amphibious brigades and divisions; two mountain brigades; aviation brigades and regiments; and two guard divisions. total strength in was Á m. including some , conscripts. reserve forces are undergoing major reorganization on a provincial basis but are estimated to number some , . there is a paramilitary people's armed police force estimated at , under pla command. in nov. the naval arm of the pla included submarines, of which three were strategic (two jin-class and one xia-class) and tactical. by mid- two more jin-class nuclear-powered ballistic missile submarines had entered service. surface combatant forces in nov. included destroyers and frigates. sea trials of china's first aircraft carrier, liaoning (a former soviet warship purchased from ukraine), began in aug. . it entered service in sept. and was initially only used for training before being declared 'combat ready' in nov. . work on china's first domestically-built aircraft carrier began in . it was launched in april and is expected to be operational by . there is a land-based naval air force of about combat-capable aircraft, primarily for defensive and anti-submarine service. the force includes h- strategic bombers and jh- fighters. the naval arm is split into a north sea fleet, an east sea fleet and a south sea fleet. in naval personnel were estimated at , , including , in the naval air force and , conscripts. the pla air force organizes its command through seven military region air forces. the air force has an estimated , combat-capable aircraft. equipment includes j- (mig- ) interceptors (known in the west as 'fishbed'), h- chinese-built copies of tu- strategic bombers, q- fighter-bombers (evolved from the mig- and known in the west as 'fantan'), su- fighters supplied by russia (known in the west as 'flanker'), j- chinese-designed and produced fighters (known in the west as 'firebird') and j- locally-developed fighters (known in the west as 'finback'). total strength ( ) was , . in agriculture accounted for Á % of gdp, industry Á % and services Á %. industry was the largest contributor until , while services only overtook agriculture as the second largest sector in . in the late s agriculture was the largest contributor towards gdp. china's economic performance has been marked by high rates of growth for over three decades. annual gdp increases in the early s consistently exceeded % until the global financial crisis. china also holds the world's largest foreign exchange reserves, at more than us$ Á trn. in april , although they have been falling since as the central bank strives to boost the currency in the face of large capital outflows. it is among the top recipients of foreign direct investment (fdi) and is the world's largest producer and consumer of coal. in china made the transition from net receiver of foreign aid to net donor and has established itself as a key player in africa's economic development, becoming the largest export partner of sub-saharan africa in . according to the world bank, china's cumulative fdi stock in africa totalled nearly us$ Á bn. in , up from us$ Á bn. in . in china overtook japan to become the world's second largest economy after the usa. new sectors like e-commerce and online financial services are gaining momentum in an economy long dominated by export-oriented sectors. rising trade tensions between the usa and china, however, pose a threat to longer-term prospects. the first steps from a centrally-planned towards a more market-oriented economy were taken by deng xiaoping in the late s. he opened the economy to foreign trade and investment, decentralized industrial management and allowed private sector development. in china became a member of the world trade organization, establishing trade relations with many countries. private entrepreneurs and foreign investors have played an important role in developing the manufacturing sector, china's principal growth engine. even before the economy was heavily skewed towards manufacturing, but following the market-oriented transition output increased significantly. during this period there was a structural shift away from large state-owned enterprises (soes), although these still remain an important part of the economy. between and the government oversaw reform of soes, with many poorly performing businesses privatized or liquidated. stronger firms were restructured and often listed on the stock market. many more recent enterprises are labour-intensive as distinct from the capitalintensive soes. growth has been fuelled by low added value and labourintensive exports. however, chinese firms are predicted to become increasingly competitive with higher added value producers, such as south korea. although the global financial crisis reduced the rate of growth and inbound fdi, china's recovery was among the earliest. gdp growth averaged Á % in the second quarter of , up from a two-decade low of Á % in the first quarter of that year. fdi also recovered rapidly, averaging Á % of gdp annually between and . growth was rooted in a stimulus package of trn. yuan (us$ bn. or % of gdp), including fiscal spending and interest rate cuts, as well as an expansionary monetary policy. central government committed Á trn. yuan, with the rest coming from local government, banks and soes. although exports declined by around % in , other countries fared worse and china's share of world exports increased to nearly Á % in (up from % in ), making it the world's largest merchandise provider. gdp growth in stood at more than % but moderated between and , reflecting the global economic slowdown and diminishing dividends from past reforms. in aug. a devaluation of the yuan sent the shanghai stock exchange plummeting by nearly %, which was swiftly followed by a surge in capital outflows. the stock market meltdown lasted until feb. , with trading halted altogether for two days in jan. that year. nonetheless, the shanghai exchange subsequently began a recovery and had stabilized (at around , points) by feb. . despite stock market turbulence, the property market, which constitutes a quarter of china's gdp and is vital to the banking sector (as it accounts for a substantial amount of its collateral), remained buoyant. gdp growth declined to Á % in (the slowest rate in years) and fell again to Á % in as china attempted to reduce its reliance on exports, increase domestic consumption and develop its service sector. however, china remains one of the fastest growing major economies in the world, recording expansions of Á % and Á % in and , respectively, driven by exports and robust domestic household consumption. in may , for the first time since , the credit rating agency moody's downgraded china's sovereign rating. inflation was Á % in , up from Á % in , while public debt was measured by the government at Á % of gdp (although there is wide-held suspicion that the real figure is significantly higher). corporate debt reached % of gdp in , with household debt-although still low-rising by % of gdp over the preceding five years. president xi jinping has targeted spending cuts and aims to curb loans to bloated soes. rapid economic advance has brought with it a number of challenges that threaten future growth. notably, china's cost advantage has been undermined in recent years by rising wages and transportation costs, as well as weak global demand. other concerns include rising property costs, high levels of local government debt, lack of enforcement of intellectual property rights, endemic corruption at government level and credit and investment dependence, while total social financing-a broad measure of total credit-increased by % of gdp between and early . the stimulus package implemented by the government to boost growth increased total debt levels to more than double the value of gdp in . according to the imf, an increase in consumer demand and a reduced dependence on exports and investment are keys to achieving stable long-term economic expansion. china's th five-year plan (covering - ) aims to promote domestic consumption and to support innovation and entrepreneurship within a framework of balanced and sustainable development. efforts to promote domestic consumption have seen exports' share of gdp falling from % in to Á % in and a lower investment contribution to gdp. trade frictions are predicted to disproportionately affect smaller firms that are less able to squeeze profit margins to accommodate tariff hikes, as well as those geographical regions most reliant on exports. the continued decline in commodity prices coupled with china's economic slowdown has had knock-on effects for commodity-exporting nations, such as brazil, indonesia and argentina, given that china consumes about half of the world's steel, aluminium and nickel. inefficient production and outmoded equipment have meanwhile led to significant environmental problems, especially in the north of the country. air pollution, soil erosion and a declining water table are of particular concern. china has become the world's largest consumer of coal and second largest consumer of oil after the usa. the government aims to diversify its energy sources, relying less on coal and more on nuclear and alternative energy sources. there has been heavy investment in hydro-power, including the three gorges dam. since , m. people have been lifted out of poverty, yet china still has the second largest number of poor in the world after india. the world bank estimates that Á m. people lived below the national poverty line at the end of (equivalent to income less than us$ per day), located mainly in remote and resource-poor regions and particularly in the west and the interior. nonetheless, some progress has been made, with Á % of the rural population living below the poverty line in compared to Á % in . a large gap remains between living standards of the urban and rural communities, between urban zones on the chinese coast and the interior and western parts of the country, and between the urban middle classes and those who have not been able to profit from the growth of recent decades. china also faces the growing burden of an ageing population. those aged and over accounted for Á % of the total population in , up from Á % in . the currency is called renminbi (i.e. people's currency). the unit of currency is the yuan (cny) which is divided into ten jiao, the jiao being divided into ten fen. the yuan was floated to reflect market forces on jan. while remaining state-controlled. for years the people's bank of china maintained the yuan at about Á to the us dollar, allowing it to fluctuate but only by a fraction of % in closely supervised trading. in july it was revalued and pegged against a 'market basket' of currencies the central parities of which were determined every night. in july , after three years of sharp appreciation, it was repegged at around Á yuan to the dollar, leading to claims from some international observers that it was being kept unfairly low to boost exports. in june the government announced that the yuan would be allowed to move freely against the dollar as long as a rise or fall does not exceed Á % within a single day. in aug. the yuan was devalued by a total of Á % on three consecutive days. in aug. total money supply was , Á bn. yuan, gold reserves were Á m. troy oz and foreign exchange reserves us$ , Á bn. (us$ Á bn. in ). china's reserves are the highest of any country, having overtaken those of japan in . inflation rates (based on imf statistics): Á % - Á % Á % Á % Á % Á % Á % Á % Á % Á % china's economy overheated in the early s, leading to inflation rates of Á % in , Á % in and Á % in of the total revenues in central government accounted for , Á bn. yuan and local governments , Á bn. yuan. tax revenues came to , Á bn. yuan in (including domestic vat , Á bn. yuan and corporate income tax , Á bn. yuan) and non-tax revenues , Á bn. yuan. of the total expenditure in central government accounted for , Á bn. yuan and local governments , Á bn. yuan. the leading items of expenditure in were education ( , Á bn. yuan) and social safety net and employment effort ( , Á bn. yuan). the standard rate of vat is %. performance gdp totalled us$ , Á bn. in , the second highest behind the usa. china's share of world gdp has risen from % in to % in . it replaced japan as the second largest economy in . it is forecast that around china will overtake the usa to become the world's largest economy. as recently as the us economy was around eight times larger than china's. real gdp growth rates (based on imf statistics): supervising the country's banks and other deposit-taking financial institutions from the central bank. legislation in permitted the establishment of commercial banks; credit co-operatives may be transformed into banks, mainly to provide credit to small businesses. there were , rural credit co-operatives at the end of . insurance is handled by the people's insurance company. the industrial and commercial bank of china is the world's largest bank by assets (us$ , bn. as at dec. ). savings deposits in various forms in all banking institutions totalled , Á bn. yuan in ; loans amounted to , Á bn. yuan. there are stock exchanges in the shenzhen special economic zone and in shanghai. a securities trading system linking six cities (securities automated quotations system) was inaugurated in for trading in government bonds. china received a record us$ Á bn. worth of foreign direct investment in , up from us$ Á bn. in . external debt totalled us$ , m. in (up from us$ , m. in ) and represented Á % of gni. china's carbon dioxide emissions from the consumption of energy in accounted for Á % of the world total (making it the biggest emissions producer, having overtaken the usa in ) and were equivalent to Á tonnes per capita (up from Á tonnes per capita in ). carbon dioxide emissions have more than doubled since . an environmental performance index compiled in ranked china th of countries, with Á %. the index examined various factors in nine areas-agriculture, air quality, biodiversity and habitat, climate and energy, fisheries, forests, health impacts, water and sanitation, and water resources. pollution is estimated to cost china about % of gdp annually. installed generating capacity in was an estimated , m. kw, compared with m. kw in . in electricity output was , , gwh, up from , , gwh in . consumption per capita was , kwh in . rapidly increasing demand has meant that more than half of china's provinces have had to ration power. sources of electricity in as percentage of total production: thermal, Á %; hydro-electric power, Á %; wind. Á % (china is one of the world's largest producers of wind power); and nuclear, Á %. in there were nuclear reactors in use and under construction. generating electricity is not centralized; local units range between and mw of output. in dec. china formally broke up its state power monopoly, creating instead five generating and two transmission firms. the three gorges dam project on the yangtze river was launched in and is intended to produce abundant hydro-electricity (as well as helping flood control). the first three , -kw generators in service at the project's hydro-power station began commercial operation in july . the original specification was completed in oct. , although six more generators have been added in the meantime (bringing the total to ). the final two generators become operational in july , giving the dam an overall capacity of Á gw. china surpassed germany in terms of solar generating capacity in , with Á gw at the end of the year. on-shore oil reserves are found mainly in the northeast (particularly the daqing and liaohe fields) and northwest. there are off-shore fields in the continental shelves of east china. oil production was a record Á m. tonnes in and was Á m. tonnes in . china is the second largest consumer of oil after the usa. ever-growing demand has meant that increasing amounts of oil are having to be imported. a -km pipeline from skovorodino in russia to daqing in the northeast of china was inaugurated in jan. , allowing china to increase significantly its imports of oil from the world's second largest producer. the , -km turkmenistan-china gas pipeline, bringing natural gas to xinjiang in china via kazakhstan and uzbekistan, was inaugurated in dec. . this connects with china's second west-east gas pipeline. only the usa imports more oil. domestic production now accounts for only % of consumption, compared to nearly % in . proven reserves in were Á bn. bbls. the largest natural gas reserves are located in the western and northcentral regions. production was a record Á bn. cu. metres in -up from Á bn. cu. metres in -with proven reserves of Á trn. cu. metres in . china is the second largest producer of wind power after the usa, with Á bn. kwh in . in total installed capacity amounted to , mw, the highest of any country and Á % of the world total. china is one of the world's leading mineral producing and consuming countries. recoverable deposits of coal in totalled Á bn. tonnes, mainly distributed in north china (particularly shanxi province and the inner mongolia autonomous region). coal production was , m. tonnes in . annual coal production has increased every year since . growing domestic demand nonetheless meant that china became a net importer of coal in . iron ore reserves were Á bn. tonnes in . deposits are abundant in the anthracite field of shanxi, in hebei and in shandong, and are found in conjunction with coal and worked in the northeast. production in was , m. tonnes, making china the world's largest iron ore producer. it is also the largest consumer, at around % of the global total in . tin ore is plentiful in yunnan, where the tin-mining industry has long existed. tin production was , tonnes in . china is a major producer of wolfram (tungsten ore). there is mining of wolfram in hunan, guangdong and yunnan. output of other minerals (in , tonnes) in : salt, , ; bauxite, , ; aluminium, , ; zinc, , ; lead, , ; copper, , . there are also reserves of diamond, nickel, barite, bismuth, graphite, gypsum, mercury, molybdenum, silver, salt, phosphate ore and sylvite. gold production, : tonnes. china surpassed south africa as the world's leading gold producer in , since when its output has increased every year. agriculture accounted for approximately % of gdp in , compared to over % in at the time of the birth of the people's republic of china and over % in . in sown areas for major crops were (in m. ha.): corn, Á ; rice, Á ; wheat, Á ; soybeans, Á ; tubers, Á ; rapeseed, Á . intensive agriculture and horticulture have been practised for millennia. present-day policy aims to avert the traditional threats from floods and droughts by soil conservancy, afforestation, irrigation and drainage projects, and to increase the 'high stable yields' areas by introducing fertilizers, pesticides and improved crops. in aug. more than m. ha., notably in the yangtze valley, were under water as china experienced its worst flooding since the s. the flood season claimed over , lives. 'township and village enterprises' in agriculture comprise enterprises previously run by the communes of the maoist era, co-operatives run by rural labourers and individual firms of a certain size. there were , state farms in with Á m. employees. net per capita annual income of rural households, : , yuan. in there were an estimated Á m. ha. of arable land and Á m. ha. of permanent cropland; Á m. ha. were equipped for irrigation. there were Á m. large/medium-sized tractors in and Á m. small tractors. china is the world's leading producer of a number of agricultural crops. production of major products (in m. tonnes), (unless otherwise indicated): corn, Á ; rice, Á ; wheat, Á ; sugarcane, Á ; potatoes ( estimate livestock, (unless otherwise indicated): pigs, , , ; sheep, , , ; goats, , , ; cattle and buffaloes, , , ; horses, , , ; chickens ( estimate), Á bn.; ducks ( estimate), m. china has more pigs, goats, sheep, horses and chickens than any other country. it is also home to nearly two-thirds of the world's ducks. meat production in was estimated at Á m. tonnes; milk, Á m. tonnes; eggs, Á m. tonnes; honey, , tonnes. china is the world's leading producer of meat, eggs and honey. gale, fred, (ed.) china's food and agriculture: issues for the st century. powell, s. g., agricultural reform in china: from communes to commodity economy, - . forestry in the area under forests was Á m. ha., or % of the total land area. the average annual increase in forest cover of , , ha. between and was the highest of any country in the world. total roundwood production in was Á m. cu. metres, making china the world's third largest timber producer ( Á % of the world total in ). it is the highest consumer of roundwood; timber consumption in totalled Á m. cu. metres. it is also the world's leading importer of roundwood, accounting for Á % of world timber imports in . total catch, : , , tonnes, of which , , tonnes were from marine waters. china's annual catch is the largest in the world, and currently accounts for approximately % of the world total. in the annual catch had been just Á m. tonnes. china's aquaculture production is also the largest in the world, at , , tonnes in . imports of fishery commodities in were valued at us$ , m. (the third highest behind japan and the usa); exports were the most of any country, at us$ , m. china's fishery commodities exports in represented approximately % of the global total. in , the first phase of the south-to-north water diversion project opened, with a second phase opening a year later. the scheme, which by provided beijing with a third of its total supply, was estimated to have cost almost us$ bn., with a third phase still to be completed. the leading companies by market capitalization in china in march were alibaba, an e-commerce and data company (us$ Á bn.); tencent holdings, an investment holding company (us$ Á bn.); and icbc, the world's largest commercial bank (us$ Á bn.). in nov. petrochina was briefly the world's largest company after its flotation on the shanghai stock market, with a market capitalization in excess of us$ trn., although its rank has since fallen considerably. industry accounted for Á % of gdp in . cottage industries persist into the st century. industrial output grew by Á % in . modern industrial development began with the manufacture of cotton textiles and the establishment of silk filatures, steel plants, flour mills and match factories. in there were , industrial enterprises with an annual revenue of more than m. yuan. of these enterprises, , were domestically funded, , were foreign funded and , were dependent on funds from hong kong, macao and taiwan. there were , state-owned industrial enterprises in total. output of major products, unless otherwise indicated (in tonnes): cement, , Á m.; rolled steel, , Á m.; crude steel, Á m.; pig iron, Á m.; gas oil and diesel oil ( ), Á m.; gasoline, Á m.; paper and paperboard, Á m.; sulphuric acid, Á m.; chemical fertilizers, Á m.; fuel oil ( ), Á m.; yarn, Á m.; refined sugar, Á m. also produced in : cloth, , m. metres; beer, , Á m. litres; , Á m. mobile phones; Á m. notebook pcs; Á m. colour tv sets; Á m. air conditioners; Á m. home refrigerators; Á m. washing machines; Á m. bicycles; Á m. cameras; Á m. motorcycles. china is the world's leading cement, steel and pig iron manufacturer; since output of cement has trebled, and production of crude steel has increased sixfold and of pig iron fivefold (although in pig iron production fell for the first time in more than years, as did crude steel production in ). china overtook japan as the world's largest producer of motor vehicles in , and in produced Á m. cars and Á m. commercial vehicles. the employed population at the census was Á m. ( Á m. female). by it had risen to Á m. ( Á m. more than in ), of whom Á m. worked in rural areas ( Á m. fewer than in ) and Á m. in urban areas ( Á m. more than in ). in china's registered urban jobless was Á %, with Á m. registered unemployed in the country's cities. with china's fast-growing ageing population, according to the united nations the working-age population began to decline in . in china had , private industrial enterprises. it was not until the late s that the private sector even came into existence in china. the average annual wage of people working in urban units in was , yuan. china's labour law stipulates a five-day working week with no more than eight hours a day and no more than hours a week. minimum working age was fixed at in . strikes over pay have become ever more frequent in china, particularly at foreign-owned facilities. china had Á m. people living in slavery according to the walk free foundation's global slavery index, the second highest total of any country. there are five special economic zones at shenzhen, xiamen, zhuhai, shantou and hainan in which concessions are made to foreign businessmen. the pudong new area in shanghai is also designated a special development area. since joint ventures with foreign firms have been permitted. a law of april reduced taxation on joint ventures to %. there is no maximum limit on the foreign share of the holdings; the minimum limit is %. in china is the second largest trading nation in the world, accounting for Á % of global merchandise imports by value in and Á % of global merchandise exports (up from Á % when it joined the wto in ). it was the second largest importer in behind the usa and the largest exporter. as recently as the usa's total trade in goods was more than twice that of china. it overtook germany as the largest exporter of goods in . its trade surplus in goods is the highest of any country. however, it has the world's highest trade deficit in services. in imports of services totalled us$ bn. but exports only us$ bn. main imports in (in us$ bn.): machinery and transport equipment, Á ; non-edible raw materials, Á ; mineral fuels, lubricants and related materials, Á ; chemicals, Á . major exports in (in us$ bn.): machinery and transport equipment, , Á ; miscellaneous manufactured goods, Á ; light textile industrial products, rubber products, minerals and metallurgical products, Á ; chemicals, Á . the main trading partners were as follows in (in us$ m.): the total road length in was , , km, including , km of expressways (of which there had not been any as recently as the mid- s); , m. tonnes of freight and , m. persons were transported by road that year. the number of civilian motor vehicles was Á m. in , including Á m. passenger vehicles and Á m. trucks (more than double the number in , when there were Á m. civilian vehicles overall including Á m. passenger vehicles and Á m. trucks). china is the world's fastest-growing car market. there were , traffic accidents in , with , fatalities. in in jan. there were , ships of gt or over registered, totalling Á m. gt. of the , vessels registered, were bulk carriers, general cargo ships, oil tankers, container ships, passenger ships and liquid gas tankers. mainland china's busiest port in was ningbo-zhoushan (handling Á m. tonnes of cargo), followed by shanghai ( Á m. tonnes), tianjin ( Á tonnes), guangzhou (canton) ( Á m. tonnes) and qingdao ( Á m. tonnes). shanghai overtook singapore to become the world's busiest container port in and handled Á m. teus (twenty-foot equivalent units) in . shenzhen, mainland china's second busiest port for container traffic and the world's fourth busiest in , handled Á m. teus. hong kong handled Á m. teus in . in jan. the first legal direct shipping links between the chinese mainland and taiwanese islands in more than years were inaugurated. inland waterways totalled , km in ; , Á m. tonnes of freight and Á m. passengers were carried. in june the three gorges reservoir on the chang jiang river, the largest water control project in the world, reached sufficient depth to support the resumption of passenger and cargo shipping. in out of countries analysed in the fragile states index-a list published jointly by the fund for peace and foreign policy magazine-china was ranked the th most vulnerable to conflict or collapse. the index is based on indicators of state vulnerability across social, political and economic categories. six new codes of law (including criminal and electoral) came into force in , to regularize the legal unorthodoxy of previous years. there is no provision for habeas corpus. as well as treason and murder the death penalty may be used for rape, embezzlement, smuggling, fraud, theft, drug-dealing, bribery and robbery with violence. amendments to the criminal law in and reduced the number of capital crimes-which include both violent and non-violent offences-from to and further to . china does not divulge figures on its use of the death penalty, but amnesty international reports that china executes thousands of people annually and is the world's top executioner. nevertheless, western analysts believe that the number of executions now is around a fifth of the yearly total in the s. 'people's courts' are divided into some higher, intermediate and , basiclevel courts, and headed by the supreme people's court. the latter, the highest state judicial organ, tries cases, hears appeals and supervises the people's courts. it is responsible to the national people's congress and its standing committee. people's courts are composed of a president, vicepresidents, judges and 'people's assessors' who are the equivalent of jurors. 'people's conciliation committees' are charged with settling minor disputes. there are also special military courts. procuratorial powers and functions are exercised by the supreme people's procuracy and local procuracies. in march the national people's congress passed legislation developing aspects of the general principles of civil law, with effect from oct. . among its provisions was the extension of legitimate rights and interests from chinese citizens only to anyone conducting civil activities in the country. in addition, the statute of limitation was increased from two to three years. the number of sentenced prisoners in mid- was , , ( per , of national population). china was ranked th of countries for criminal justice and th for civil justice in the world justice project rule of law index, which provides data on how the rule of law is experienced by the general public across eight categories. an educational reform of brought in compulsory nine-year education consisting of six years of primary schooling and three years of secondary schooling, to replace a previous five-year system. in mainland china the population census revealed the following levels of educational attainment: Á m. people had finished university education; Á m. had received senior secondary education; Á m. had received junior secondary education; and Á m. had had primary education. Á m. people over years of age or Á % of the population were illiterate, although this compared favourably with a Á % rate of illiteracy in the census and a Á % rate in . in adult literacy was estimated at Á %; youth literacy in was Á %. in there were , kindergartens with Á m. children and Á m. full-time teachers; , regular primary schools with Á m. pupils and Á m. full-time teachers; , secondary schools (including: , senior secondary; , junior secondary; , specialized; , vocational; and , technical) with Á m. pupils and Á m. full-time teachers. there were also , pupils at , special education schools. institutes of higher education, including universities, numbered , in , with Á m. undergraduates and Á m. postgraduate level students, and Á m. full-time teaching staff. china has more than private universities, almost all of which have been established since the mid- s. a national system of student loans was established in . the number of chinese students studying abroad went up from , in to , in ; it rose above , in and , in , and by exceeded , , making china the largest source of overseas students in the world. chinese students account for a fifth of all international students in tertiary education in the oecd, but fewer than half return to china after finishing their studies. the number of chinese undergraduate students in american universities in - was times as many as in - , rising from , to , in the space of seven years. there is an academy of sciences with provincial branches. an academy of social sciences was established in . in national government expenditure on education came to , , m. yuan and accounted for Á % of national government spending. medical treatment is free only for certain groups of employees, but where costs are incurred they are partly borne by the patient's employing organization. in there were , health institutions throughout china, including , hospitals, , local health centres, , centres for disease control and prevention, and , specialized prevention and treatment centres. china's first aids case was reported in . at the end of there were , reported cases of people living with hiv/aids. the number of deaths of people who had been living with hiv/aids in was , . in the first half of china was struck by an epidemic of a pneumoniatype virus identified as sars (severe acute respiratory syndrome). the virus was first detected in southern china and was subsequently reported in over other countries. according to the ministry of health, by the time the outbreak had been contained a total of , cases had been reported on the chinese mainland; , patients were cured and discharged from hospital, and died. in water: at what cost? the state of the world's water , wateraid reported that Á % of the population does not have access to safe water. china ranked as the country with the second largest number of people living without access to safe water ( Á m. in ). in an estimated Á % of adult males and Á % of adult females smoked in china. a study from the same year estimated that chinese males smoke one-third of all the world's cigarettes. in there were , social welfare enterprises with Á m. beds. numbers (in , ) of beneficiaries of relief funds in : urban residents receiving minimum living allowance, , ; rural residents receiving minimum living allowance, , ; persons receiving traditional relief, ; persons in rural households entitled to the 'five guarantees' (food, clothing, medical care, housing and burial expenses), , . the official retirement age for men is and for women (or in the case of civil servants and professionals). the government accords legality to five religions only: buddhism, islam, protestantism, roman catholicism and taoism. confucianism, buddhism and taoism have long been practised. confucianism has no ecclesiastical organization and appears rather as a philosophy of ethics and government. taoism-of chinese origin-copied buddhist ceremonial soon after the arrival of buddhism two millennia ago. buddhism in return adopted many taoist beliefs and practices. a more tolerant attitude towards religion had emerged by , and the government's bureau of religious affairs (since renamed the state administration for religious affairs) was reactivated. ceremonies of reverence to ancestors have been observed by the whole population regardless of philosophical or religious beliefs. a new quasi-religious movement, falun gong, was founded in , but has since been banned by the authorities. the movement has claimed some m. adherents, although the chinese government has disputed this. muslims are found in every province of china, being most numerous in the ningxia-hui autonomous region, yunnan, shaanxi, gansu, hebei, henan, shandong, sichuan, xinjiang and shanxi. roman catholicism has had a footing in china for more than three centuries. two christian organizations-the chinese patriotic catholic association, which declared its independence from rome in , and the protestant three-self patriotic movement-are sanctioned by the chinese government. according to estimates (by the state-approved xinhua news agency, the chinese academy of social sciences and the state administration for religious affairs) there were m. buddhists (more than in any other country), m. christians and more than m. muslims in the country in . other official figures indicate that there are Á m. catholics, although unofficial estimates are much higher. the number of christians in china is generally thought to be far higher than official numbers indicate, with so-called 'house churches' becoming ever more popular. some analysts estimate that there are as many as m. christians overall. legislation of prohibits foreign nationals from setting up religious organizations. johnson, ian, the souls of china: the return of religion after mao. china and provides habitat for a number of rare animal species, kulangsu, a historic international settlement ( ), a tiny island located on the estuary of the chiu-lung river, qinghai hoh xil ( ), the largest and highest plateau in the world, and fanjingshan ( ), an island of metamorphic rock in guizhou province. shared with kazakhstan and kyrgyzstan, silk roads: the routes network of chang'an-tianshan corridor ( ) is a , -km section of the extensive silk roads network stretching from chang'an/ luoyang to the zhetysu region in present-day kazakhstan. china has two news agencies: xinhua (new china) news agency (the nation's official agency) and china news service. in there were , newspapers and , magazines; , m. copies of newspapers and , m. copies of magazines were published. in there were fewer than newspapers. the communist party newspaper, renmin ribao (people's daily), had an average daily circulation of Á m. in . the most widely read newspaper is cankao xiaoxi, with an average daily circulation of Á m. in . china has the second highest circulation of daily newspapers after india, with an estimated average daily total of Á m. in . as of sept. it was also home to the world's two most visited online news sites: xinhua news agency ( Á m. unique desktop users per month) and people's daily online ( Á m.). in the world press freedom index compiled by reporters without borders, china ranked rd out of countries. in , , m. volumes of books were produced. in tourist numbers totalled Á m. china was the fourth most visited destination in after france, the usa and spain. income from tourists in was us$ Á bn., ranking it third behind the usa and spain. expenditure by chinese travellers outside of mainland china for was us$ Á bn., the most of any country and more than double the next largest expenditure (that of us tourists). in both german and us travellers abroad had spent more than those from china. the lunar new year, also known as the 'spring festival', is a time of great excitement for the chinese people. the climate is sub-tropical, tending towards temperate for nearly half the year, the winter being cool and dry and the summer hot and humid, may to sept. being the wettest months. normal temperatures are jan. f ( Á c), july f ( Á c). annual rainfall " ( , Á mm). hong kong used to be administered by the hong kong government. the governor was the head of government and presided over the executive council, which advised the governor on all important matters. the last british governor was chris patten. in oct. the executive council consisted of three ex officio members and ten appointed members, of whom one was an official member. the chief functions of the legislative council were to enact laws, control public expenditure and put questions to the administration on matters of public interest. the legislative council elected in sept. was, for the first time, constituted solely by election. it comprised members, of whom were elected from geographical constituencies, from functional constituencies encompassing all eligible persons in a workforce of Á m., and ten from an election committee formed by members of district boards. a president was elected from and by the members. at the elections on sept. turnout for the geographical seats was Á %, and for the functional seats ( of which were contested), Á %. the democratic party and its allies gained seats, the liberal party and the pro-beijing democratic alliance . the remaining seats went to independents. on dec. the selection committee selected a provisional legislature which began its activities in jan. while the legislative council was still functioning. in jan. the provisional legislature started its work by enacting legislation which would be applicable to the hong kong special administrative region and compatible with the basic law. constitutionally hong kong is a special administrative region of the people's republic of china. the basic law enables hong kong to retain a high degree of autonomy. it provides that the legislative, judicial and administrative systems which were previously in operation are to remain in place. the special administrative region government is also empowered to decide on hong kong's monetary and economic policies independent of china. in july the first-past-the-post system of returning members from geographical constituencies to the legislative council was replaced by proportional representation. there were directly elected seats out of for the first elections to the legislative council following hong kong's return to chinese sovereignty, increasing in accordance with the basic law to for the election with indirectly elected. in the sept. legislative council election (and that of sept. ) of the seats were directly elected. for the election in sept. the number of seats was increased to , with directly elected and indirectly elected by functional constituencies. there were also five new functional constituency seats nominated by elected district council members. the chief executive is chosen by a beijing-backed , -member election committee ( prior to the march election), although it has been stated that universal suffrage is the ultimate aim. in a timetable was announced for hong kong to directly elect its chief executive in and its legislative council in . however, beijing insisted that only approved candidates would be allowed to stand in , prompting mass pro-democracy rallies in the territory in and formal rejection of the plan by the legislative council in june . beijing nevertheless refused to countenance amendments. in july a new accountability or 'ministerial' system was introduced, under which the chief executive nominates for appointment policy secretaries, who report directly to the chief executive. the chief executive is aided by the executive council, consisting of the three senior secretaries of department (the chief secretary, the financial secretary and the secretary for justice) and eleven other secretaries plus five non-officials. hong kong used to be administered by the hong kong government. the governor was the head of government and presided over the executive council, which advised the governor on all important matters. the last british governor was chris patten. in oct. the executive council consisted of three ex officio members and ten appointed members, of whom one was an official member. the chief functions of the legislative council were to enact laws, control public expenditure and put questions to the administration on matters of public interest. the legislative council elected in sept. was, for the first time, constituted solely by election. it comprised members, of whom were elected from geographical constituencies, from functional constituencies encompassing all eligible persons in a workforce of Á m., and ten from an election committee formed by members of district boards. a president was elected from and by the members. at the elections on sept. turnout for the geographical seats was Á %, and for the functional seats ( of which were contested), Á %. the democratic party and its allies gained seats, the liberal party and the pro-beijing democratic alliance . the remaining seats went to independents. overview hong kong has one of the world's most open economies and is an internationally important financial centre. the territory's economic rise was founded on its role as an international trade emporium, acting as a conduit for china's burgeoning exports. mainland china, the usa and japan are hong kong's major export partners, accounting for Á %, Á % and Á % of exports respectively in . the island is dependent on imports of food and other resources. in it imported % of goods from mainland china, % from taiwan and % from japan. in and the economy grew strongly on the back of a rise in chinese tourism, healthy global demand for exports and improving domestic consumer confidence. however, the global financial crisis saw the economy shrink by Á % in before rebounding with a Á % increase the following year. between and annual growth averaged Á %, supported by strong external demand. student-led pro-democracy protests in the latter months of caused major disruption in several key business districts and threatened to weaken the local economy in the short term. foreign direct investment levels have been high, averaging % of gdp between and according to world bank data, and the world economic forum ranked hong kong as the ninth most competitive economy in the world in its report. the government aims to tackle a housing shortage by providing , new housing units by the mid- s. the unit of currency is the hong kong dollar (hkd) of cents. it has been pegged since at a rate of hk$ Á to the us dollar. banknotes are issued by the hongkong and shanghai banking corporation and the standard chartered bank, and, from may , the bank of china. total money supply was hk$ , m. in july . in aug. gold reserves were , troy oz and foreign exchange reserves were us$ , m. inflation rates (based on imf statistics): environment hong kong's carbon dioxide emissions from the consumption of energy in were the equivalent of Á tonnes per capita. installed capacity was Á m. kw in . production in was Á bn. kwh. hong kong is a net importer of electricity. consumption in was Á bn. kwh. the local agricultural industry is directed towards the production of high quality fresh food through intensive land use and modern farming techniques. out of the territory's total land area of , sq. km, only sq. km is currently farmed. in local production accounted for % of live poultry consumed, % of live pigs and % of fresh vegetables. the gross value of local agricultural production totalled hk$ , m. in , with pig production valued at hk$ m., poultry production (including eggs) at hk$ m., and vegetable and flower production at hk$ m. in the total catch was , tonnes, exclusively from marine waters. the leading companies by market capitalization in hong kong in march were: china mobile, a telecommunications company (us$ Á bn.); aia group, a life insurance company (us$ Á bn.); and cnooc, an integrated oil company (us$ Á bn.). industry is mainly service-oriented. in june there were , establishments employing , , persons in service industries and , establishments employing , persons in manufacturing industries. establishment statistics by service type (and persons engaged) were mainly: import/export trade and wholesale, , ( , ); retail, , ( , ); social and personal services, , ( , ) ; professional and business services, , ( , ); financing and insurance, , ( , ); accommodation and food services, , ( , ); real estate, , ( , ) . in the size of the labour force (synonymous with the economically active population) was , , ( , , females). the persons engaged in june included , , people in wholesale, retail and import/ export trades, accommodation and food services, , in finance, insurance, real estate, professional and business services, , in the civil service, , in manufacturing and , in construction sites (manual workers only). a minimum wage of hk$ per hour was introduced for the first time on may . unemployment stood at Á % in the period sept.-dec. . in the total value of imports was hk$ , , m. and total exports hk$ , , m. the main suppliers of imports in were mainland china ( Á %), japan ( Á %), taiwan ( Á %), singapore ( Á %) and usa ( Á %). in , Á % of total exports went to mainland china, Á % to the usa, Á % to japan, Á % to germany and Á % to the united kingdom. the chief import items in were: electrical machinery, apparatus and appliances, etc. ( Á %); telecommunications, sound recording and reproducing equipment ( Á %); office machines and automatic data processing machines ( Á %); articles of apparel and clothing accessories ( Á %). the main exports in were: electrical machinery, apparatus and appliances, etc. ( Á %); telecommunications, sound recording and reproducing equipment ( Á %); office machines and automatic data processing machines ( Á %); articles of apparel and clothing accessories ( Á %). in there were , km of roads, over % of which were in the new territories. there are road tunnels, including three under victoria harbour. in there were , private cars, , goods vehicles, , buses and coaches, and , motorcycles and mopeds. there were , road accidents in , of which were fatal. a total of Á m. tonnes of cargo were transported by road in . a km bridge (the world's longest sea bridge) linking hong kong, zhuhai in guangdong province in mainland china and macao opened in oct. following a number of delays. hong kong was ranked fourth for its road infrastructure in the world economic forum's global competitiveness report - . hong kong's railways are run by the mtr corporation limited (mtrcl), a public listed company of which the government is the majority shareholder. the mtr system comprises nine railway lines serving hong kong island, kowloon and the new territories. its km network has stations and carries an average of Á m. passengers each day. mtr lines carried , m. passengers in . in addition, a light rail network ( Á km and stops) serves the local communities of tuen mun, yuen long and tin shui wai in the new territories; , passengers travel daily on the system. a high speed rail service between hong kong and guangzhou on the mainland opened in sept. . the electric tramway on the northern state of hong kong island commenced operating in and has a total track length of km. the peak tram, a funicular railway connecting the peak district with the lower levels in victoria, has a track length of Á km and two tramcars (each with a capacity of passengers per trip). it carries an average of , passengers daily. the airport express line ( Á km) opened in and is also operated by the mtrcl. it carried Á m. passengers in . in june it was estimated that Á m. passenger journeys were made daily on public transport (including local railways, buses, etc.). in the world economic forum's global competitiveness report - hong kong ranked third for quality of rail infrastructure. the new hong kong international airport (generally known as chek lap kok), built on reclaimed land off lantau island to the west of hong kong, was opened on july to replace the old hong kong international airport at kai tak, which was situated on the north shore of kowloon bay. more than airlines now operate scheduled services to and from hong kong. in cathay pacific airways, the largest hong kong-based airline, operated approximately , passenger and cargo services to destinations in countries and territories around the world. cathay pacific carried , , passengers and Á m. tonnes of cargo in . dragonair, a cathay pacific subsidiary, provided scheduled services to cities in mainland china and asia in . in air hong kong, an all-cargo operator, provided scheduled services to bangkok, beijing, ho chi minh city, manila, nagoya, osaka, penang (via bangkok), seoul, shanghai, singapore, taipei and tokyo. hong kong international airport handled more international freight in than any other airport. in , , aircraft arrived and departed and m. passengers and Á m. tonnes of freight were carried on aircraft. hong kong was second, behind only singapore, in the rankings for air transport infrastructure in the world economic forum's global competitiveness report - . the port of hong kong handled Á m. teus (twenty-foot equivalent units) in , making it the world's third busiest container port after shanghai and singapore. the kwai chung container port has berths with , metres of quay backed by ha. of cargo handling area. at the end of there were , ships ( , ocean-going) of , , gt registered in hong kong. in , , ocean-going vessels, , river cargo vessels and , river passenger vessels arrived at the port of hong kong. a total of m. tonnes of freight were handled in . hong kong was ranked third in the world economic forum's global competitiveness report - for the quality of its port facilities. in there were , , main (fixed) telephone lines (equivalent to Á per , population). the local fixed telecommunications network services (ftns) market in hong kong was liberalized in . there were , , mobile phone subscriptions in (equivalent to , Á per , population), up from , , in ( , Á per , population). the number of subscriptions doubled between and . the internet market has also seen huge growth. in there were , , wireless broadband subscriptions ( Á per , population) and , , fixed broadband subscriptions ( Á per , population). the number of fixed broadband subscriptions has been declining since as more people have wireless subscriptions instead. in march there were Á m. facebook users. the external telecommunications services market has been fully liberalized since jan. , and the external telecommunications facilities market was also liberalized starting from jan. . in the adult literacy rate was Á % ( Á % in ). universal basic education is available to all children aged from six to years. in around three-quarters of the ordinary secondary day schools teaching has been in cantonese since - , with about a quarter of ordinary secondary day schools still using english. in there were , pupils in kindergartens, , in primary schools (including international schools) and , in secondary schools (including international schools). the estimated total government expenditure on education in - was hk$ Á bn. ( Á % of total government spending and Á % of gdp). in - : Á % of total government spending and Á % of gdp. according to the oecd's pisa (programme for international student assessment) study, -year-olds in hong kong rank second among oecd and other major countries and cities in mathematics and reading, and ninth in science. the three-yearly study compares educational achievement of pupils in over countries. the department of health (dh) is the government's health adviser and regulatory authority. the hospital authority (ha) is an independent body responsible for the management of all public hospitals. in there were , registered doctors, equivalent to Á doctors per , population. in there were , dentists, , nurses and , midwives. the total number of hospital beds in was , , including , beds in public hospitals under the ha and , beds in private hospitals. the bed-population ratio was Á beds per thousand population. the chinese medicine ordinance was passed by the legislative council in july to establish a statutory framework to accord a professional status for chinese medicine practitioners and ensure safety, quality and efficacy of chinese medicine. in there were , registered chinese medicine practitioners. total expenditure on health in - amounted to hk$ , m., an increase of Á % over that in - . the hong kong act of provided for hong kong ordinances to replace english laws in specified fields. the courts of justice comprise the court of final appeal (inaugurated july ), which hears appeals on civil and criminal matters from the high court; the high court (consisting of the court of appeal and the court of first instance); the lands tribunal, which determines on statutory claims for compensation over land and certain landlord and tenant matters; the district court (which includes the family court); the magistracies (including the juvenile court); the coroner's court; the labour tribunal, which provides a quick and inexpensive method of settling disputes between employers and employees; the small claims tribunal, which deals with monetary claims involving amounts not exceeding hk$ , ; and the obscene articles tribunal. while the high court has unlimited jurisdiction in both civil and criminal matters, the district court has limited jurisdiction. the maximum term of imprisonment it may impose is seven years. magistracies exercise criminal jurisdiction over a wide range of offences, and the powers of punishment are generally restricted to a maximum of two years' imprisonment or a fine of hk$ , . after being in abeyance for years, the death penalty was abolished in . , crimes were reported in , of which , were violent crimes. , people were arrested in , of whom , were for violent crimes. the population in penal institutions was , at dec. ( per , population). social welfare programmes include social security, family services, child care, services for the elderly, medical social services, youth and community work, probation, and corrections and rehabilitation. non-governmental organizations are subsidized by public funds. the government gives non-contributory cash assistance to needy families, unemployed able-bodied adults, the severely disabled and the elderly. caseload as at aug. totalled , . victims of natural disasters, crimes of violence and traffic accidents are financially assisted. estimated recurrent government expenditure on social welfare for - was hk$ Á bn. in there were daily newspapers, of which were paid-for and four free. the newspapers with the highest circulation figures are all chinese-language papers-oriental daily news, apple daily and the sun. the english-language paper with the highest circulation is the south china morning post. circulation of dailies (including free papers) in was Á m. ( Á m. paid-for and Á m. free). there were a record , , visitor arrivals in . expenditure associated to inbound tourism totalled hk$ , Á m. in . the macao special administrative region, which lies at the mouth of the pearl river, comprises a peninsula ( Á sq. km) connected by a narrow isthmus to the people's republic of china, on which is built the city of santa nome de deus de macao, the islands of taipa ( Á sq. km), linked to macao by three bridges, colôane ( Á sq. km) linked to taipa by a -km causeway, and cotai, a strip of reclaimed land between colôane and taipa ( Á km). the total area of macao in was Á sq. km. additional land continues to be reclaimed from the sea. the population at the census was , ( , females); density, , people per sq. km. according to un estimates, the entire population lived in urban areas in . the official languages are chinese and portuguese, with the majority speaking the cantonese dialect. only about , people speak portuguese as their first language. the un gives a projected population for of , . in , , foreigners were legally registered for residency in macao. there were , legal immigrants from mainland china. social statistics : births, , ( Á per , population); deaths, , ( Á ); marriages, , ( Á ); divorces, , ( Á ). infant mortality, , Á per , live births. life expectancy at birth , Á years. sub-tropical tending towards temperate, with an average temperature of Á c. the number of rainy days is around a third of the year. average annual rainfall varies from - " ( , - , mm) . it is very humid from may to sept. macao's constitution is the 'basic law', promulgated by china's national people's congress on march and in effect since dec. . it is a special administrative region (sar) of the people's republic of china, and is directly under the central people's government while enjoying a high degree of autonomy. the legislative assembly has seats of which are directly elected, indirectly elected by functional constituencies and seven appointed by the chief executive. at the elections held on sept. the macau-guangdong union won two of elected seats with Á % of votes cast and the union for development two with Á %. ten other parties won a single seat each. turnout was Á %. fernando chui sai-on was re-elected chief executive for a second term on aug. , receiving out of votes in the election committee. chief executive: fernando chui sai-on; b. (sworn in dec. and re-elected in aug. . government website: http://www.gov.mo the gaming sector is of major importance to the economy of macao. it accounted for Á % of total gdp in and provides billions of dollars in taxes. in , Á % of the workforce was employed in gaming. in gross gaming revenue totalled us$ , m. (nearly double the figure) . however, revenues were down slightly on the total. macao overtook nevada as the world's largest gaming market in . macao's traditional manufacturing industries virtually disappeared following the transfer of much of the textile industry to the chinese mainland and, in , the termination of the multifibre arrangement, which had governed international textile trade flows for three decades. the unit of currency is the pataca (mop) of avos, which is tied to the hong kong dollar at parity. inflation was Á % in and Á % in . foreign exchange reserves were us$ , m. in . total money supply was , m. patacas in . in revenues totalled , m. patacas; expenditures, , m. patacas. revenues from gaming tax accounted for Á % of total revenue in ; current expenditure accounted for Á % of expenditure. real gdp growth was just Á % in but then rose to Á % in and Á % in . more recently the economy contracted by Á % in before growing by Á % in . total gdp in was us$ Á bn. environment macao's carbon dioxide emissions from the consumption of energy in were the equivalent of Á tonnes per capita. installed capacity was Á m. kw in ; production, Á bn. kwh. macao imported , m. kwh of electricity in . oil and gas , , litres of fuel oil were imported in . the catch in was estimated at , tonnes. although the economy is based on gaming and tourism there is a light industrial base of textiles and garments. in the number of manufacturing establishments was (food products and beverages, ; textiles and wearing apparel, ; publishing, printing and reproduction of recorded media, ). in a total of , people were in employment, including , ( Á %) in gaming and junket activities (up from , in ); , ( Á %), hotels, restaurants and similar activities; , ( Á %), construction; , ( Á %), wholesale and retail trade, repair of motor vehicles, motorcycles and personal and household goods; , ( Á %), real estate and business activities; , ( Á %), public administration and social security. employment in was Á % of the labour force; unemployment rate stood at Á %. in imports (c.i.f.) were valued at us$ , Á m., of which the main products were telecommunications, sound recording and reproducing equipment; petroleum and petroleum products; and gold, silverware, jewellery and articles of precious materials. in the chief import sources (in us$ m.) were: mainland china ( , Á ); hong kong ( Á ); japan ( Á ). exports (f.o.b.) were valued at us$ Á m., of which the leading products were articles of apparel and clothing accessories; gold, silverware, jewellery and articles of precious materials; and petroleum oils and oils obtained from bituminous minerals. in the main export markets (in us$ m.) were: hong kong ( Á ); usa ( Á ); mainland china ( Á ). in there were km of roads. in there were , passenger cars in use ( cars per , inhabitants), , buses and coaches, , trucks and , motorcycles. there were fatalities in road accidents in . a km bridge (the world's longest sea bridge) linking macao, zhuhai in guangdong province in mainland china and hong kong opened in oct. following a number of delays. an international airport opened in dec. . in macau international airport handled , , passengers and , tonnes of freight (including transit cargo). in air macau flew to bangkok, beijing, changsha, chengdu, chongqing, da nang, hangzhou, hefei, kaohsiung, nanjing, nanning, ningbo, osaka, quanzhou, seoul, shanghai, shenyang, taipei, taiyuan, tokyo, wenzhou, xiamen and zhengzhou. regular services connect macao with hong kong, km to the northeast. in there were , landline telephone subscriptions (equivalent to Á per , inhabitants) and , , mobile phone subscriptions (or , Á per , inhabitants). in , Á % of households had internet access. in march there were , facebook users. there are a judicial district court, a criminal court and an administrative court with magistrates in all. in there were , crimes, of which , were against property. there were persons in prison in dec. . there are both public and private schools. in - there were schools and colleges. number of students in the - academic year (with number of teachers): pre-primary, , ( ); primary, , ( , ); secondary, , ( , ). in - there were four special education schools with pupils and teachers. there were ten higher education institutions with student enrolment of , . in there were institutions offering vocational training courses, in which participants totalled , . expenditure on education came to Á % of gdp in and Á % of total government spending in . in there were doctors, dentists and nurses working in primary health care, and doctors, dentists and , nurses working in hospitals. in there were , hospital beds; there were Á doctors per , population. in there were an estimated , folk religionists and , buddhists according to the pew research center's forum on religion & public life. a further , people were religiously unaffiliated. there are also small numbers of catholics. the historic centre of macao was inscribed on the unesco world heritage list in . in there were daily newspapers (nine in chinese, three in portuguese and two in english) and weekly newspapers (ten in chinese and one in portuguese). tourism is one of the mainstays of the economy. in there were Á m. tourists (of which Á m. were from mainland china, Á m. from hong kong and Á m. from taiwan), up from Á m. in and Á m. in . visitor spending in totalled , m. patacas. the government-run macao international music festival featuring a wide range of chinese and western music takes place in oct.-nov. in july president lee teng-hui repudiated taiwan's -year-old 'one china' policy-the pretence of a common goal of unification-arguing that taiwan and china should maintain equal 'state to state' relations. this was a rejection of beijing's view that taiwan is no more than a renegade chinese province which must be reunited with the mainland, by force if necessary. in the presidential election of march chen shui-bian, leader of the democratic progressive party, was elected, together with annette lu hsiu-lien as his vice president. both supported independence although chen shui-bian made friendly gestures towards china and distanced himself from colleagues who wanted an immediate declaration of independence. following his wife's indictment on embezzlement charges in nov. , president chen survived three parliamentary attempts to impeach him. he was succeeded as president in by ma ying-jeou of the nationalist party. in sept. chen shui-bian received a life sentence (later reduced to a -year term) after being found guilty of multiple counts of corruption. china and taiwan signed a free trade agreement in june , which was considered a significant thawing of relations. nonetheless, tensions remained, particularly in relation to disputed sovereignty over several islands in the east china sea. in jan. ma ying-jeou was re-elected to the presidency but the election in jan. was won by tsai ing-wen, whose democratic progressive party won the most seats in legislative polls at the same timethe first occasion that the nationalist party has not been the largest party in government since . the climate is subtropical in the north and tropical in the south. the typhoon season extends from july to sept. the average monthly temperatures of jan. and july in taipei are Á f ( Á c) and Á f ( Á c) respectively, and average annual rainfall is Á " ( , Á mm). kaohsiung's average monthly temperatures of jan. and july are Á f ( Á c) and Á f ( Á c) respectively, and average annual rainfall is Á " ( , Á mm). the roc constitution is based on the principles of nationalism, democracy and social wellbeing formulated by dr sun yat-sen, the founding father of the republic of china. the roc government is divided into three main levels: central, provincial/municipal and county/city, each of which has welldefined powers. the central government consists of the office of the president, the national assembly, which is specially elected only for constitutional amendment, and five governing branches called 'yuan', namely the executive yuan, the legislative yuan, the judicial yuan, the examination yuan and the control yuan. beginning with the elections to the seventh legislative yuan held on jan. the legislative yuan has members (formerly ). of the members are elected under the first-past-the-post system in singlemember constituencies, are filled by proportional representation in accordance with a nationwide party vote and six are reserved for aboriginal candidates. since the president has been directly elected. since a resolution on the impeachment of the president or vice president is no longer to be instituted by the control yuan but rather by the legislative yuan. the legislative yuan has the power to pass a no-confidence vote against the premier of the executive yuan, while the president of the republic has the power to dissolve the legislative yuan. the premier of the executive yuan is directly appointed by the president of the republic. in dec. a law came into effect allowing for referendums to be held. professional force-a process that was originally scheduled to start in and end in but has been delayed owing to low recruitment levels. defence expenditure in totalled us$ , m. (us$ per capita), representing Á % of gdp. the republic of china army conducts ground combat missions as well as air support and airborne special operations. it was estimated to number about , personnel in , with reserves numbering Á m. its principal role is to defend against a possible amphibious assault from the chinese mainland by the people's liberation army. in addition there are paramilitary forces totalling , personnel. navy personnel in totalled , , with , reservists. the forces consist of four submarines, four cruisers and frigates. there are also missile craft for patrol and coastal defence, mine-laying vehicles and amphibious landing craft. in the air force numbered , personnel with , reservists. there were combat-capable aircraft in the same year including f- es, f- s and mirage - s. taiwan has made a successful transition from an agricultural economy to one based on high-tech electronics. economic growth averaged % per year over three decades from the s, driven primarily by high value-added manufacturing and exports, especially in electronics and computers. government-owned enterprises, including banks, have been privatized. though largely escaping the impact of the asian financial crisis, the economy went into recession in with the first year of negative growth ever recorded and unemployment reaching record highs. strong export performance stimulated a recovery, with annual gdp growth above % from - . inflation has been consistently low and unemployment, which fell below % in , has averaged between and % since the turn of the century. owing to its heavy dependence on exports, taiwan suffered a severe downturn as a result of the global financial crisis in . major export industries such as semiconductors and memory chips declined, unemployment reached its highest levels since and, in , the economy again went into recession. a us$ Á bn. stimulus package boosted recovery and in the economy recorded its highest growth rate for nearly three decades, at Á %. however, growth subsequently cooled owing to lower demand from developed nations, averaging Á % per year between and . tourism has grown in importance, with over Á m. visitors in constituting taiwan's highest annual number to date. an ageing population and high savings rates threaten to constrain domestic demand in the future. the unit of currency is the new taiwan dollar (twd) of cents. gold reserves were Á m. oz in dec. . there was inflation of Á % in and Á % in . foreign exchange reserves were us$ Á bn. in dec. . in general government revenues totalled nt$ , , m. and expenditures nt$ , , m. tax revenue accounted for Á % of revenues in ; education, science and culture accounted for Á % of expenditures, economic development Á % and general administration Á %. vat is %. taiwan sustained rapid economic growth at an annual rate of Á % from up to . the rate slipped to Á % in the s and Á % in ; taiwan suffered from the asian financial crisis, though less than its neighbours. in global economic sluggishness and the events of sept. in the usa severely affected taiwan's economy, which contracted by Á %. subsequent economic recovery led to growth of Á % in and Á % in . there was negative growth of Á % in but again the economy bounced back, and grew by Á % in and Á % in . the central bank of the republic of china (taiwan), reactivated in , regulates the money supply, manages foreign exchange and issues currency. the governor is yang chin-long. the bank of taiwan is the largest commercial bank and the fiscal agent of the government. there are seven domestic banks, commercial banks and foreign banks. there are two stock exchanges in taipei. taiwan's carbon dioxide emissions from the consumption of energy in were the equivalent of Á tonnes per capita. output of electricity in was Á m. mwh; total installed capacity was , mw. there were six units in three nuclear power stations in . crude oil production in was , bbls; natural gas, m. cu. metres. taiwan imports most of the oil and natural gas that it consumes. in the cultivated area was , ha., of which , ha. were paddy fields. rice production totalled , , tonnes. livestock production was valued at nt$ , m., accounting for % of taiwan's total agricultural production value. forest area, : , , ha. forest reserves: trees, , , cu. metres; bamboo, , m. poles. timber production, , cu. metres. the catch in was , tonnes, almost exclusively from sea fishing. the largest companies in taiwan by market capitalization in march were: taiwan semiconductor manufacturing (us$ Á bn.); hon hai precision industry, an electronics manufacturer (us$ Á bn.); and chunghwa telecom (us$ Á bn.). output (in tonnes) in : crude steel; Á m.; cement, Á m.; cotton fabrics, Á m. sq. metres; integrated circuit packages, Á trn. units; global positioning system (gps) sets, Á bn. units. in the average total labour force was Á m., of whom Á m. were employed. of the employed population, Á % worked in manufacturing; Á % in wholesale and retail trade; Á % in construction; Á % in accommodation and food services; Á % in education; Á % in agriculture, forestry and fisheries. the unemployment rate was Á %. in there were , km of roads. in , Á m. passenger cars, , buses and coaches, Á m. lorries and vans, and Á m. motorcycles and mopeds were in use. , m. passengers and m. tonnes of freight were transported in . there were , fatalities in road accidents in . in freight traffic amounted to Á m. tonnes and passenger traffic to m. total route length was , km. there are metro systems in taipei (opened in ) , kaohsiung (opened in ) and taoyuan (opened in ). there are currently two international airports: taiwan taoyuan international airport at taoyuan near taipei, maritime transportation is vital to the trade-oriented economy of taiwan. in jan. there were ships of gt or over registered, totalling Á m. gt. of the vessels registered, were general cargo ships, bulk carriers, container ships, oil tankers and nine passenger ships. there are six international ports: kaohsiung, keelung, taichung, hualien, anping and suao. the first three are container centres, kaohsiung handling Á m. -ft equivalent units in , making it the world's th busiest container port in terms of number of containers handled. suao port is an auxiliary port to keelung. in jan. the first legal direct shipping links between taiwanese islands and the chinese mainland in more than years were inaugurated. in there were , , landline telephone subscribers ( Á per , inhabitants). taiwan's biggest telecommunications firm, the stateowned chunghwa telecom, lost its fixed-line monopoly in aug. . in there were , , mobile phone subscriptions, equivalent to , Á per , persons. in there were Á mobile broadband subscriptions per inhabitants and Á fixed broadband subscriptions per inhabitants. in march there were Á m. facebook users. the judicial yuan is the supreme judicial organ of state. comprising grand justices, since these have been nominated and, with the consent of the legislative yuan, appointed by the president of the republic. the grand justices hold meetings to interpret the constitution and unify the interpretation of laws and orders. there are three levels of judiciary: district courts and their branches deal with civil and criminal cases in the first instance; high courts and their branches deal with appeals against judgments of district courts; the supreme court reviews judgments by the lower courts. there is also the supreme administrative court, high administrative courts and a commission on the disciplinary sanctions of public functionaries. criminal cases relating to rebellion, treason and offences against friendly relations with foreign states are handled by high courts as the courts of first instance. the death penalty is still in force. there were no executions in but there was one in . the population in penal institutions in april was , ( per , of national population). since there has been compulsory education for six to -year-olds with free tuition. the illiteracy rate dropped from Á % in to Á % by . there were , primary schools, , secondary schools and vocational schools in ; and universities, colleges and junior colleges. in - there were , , pupils with , teaching staff at elementary schools; , pupils and , teaching staff at junior high schools; , pupils and , teaching staff at senior high schools; and , students and , teaching staff at senior vocational schools. there were , , students in universities and colleges in - with , academic staff. in there were , physicians (one for every persons), , doctors of chinese medicine, , nurses, , dentists and assistants, and , pharmacists and assistants. in there were , medical facilities serving , persons per facility; there were , beds and Á beds per , persons. in cancers, heart diseases, cerebrovascular diseases, diabetes and accidents were the first five leading causes of death. a universal health insurance scheme came into force in as an extension to social insurance plans that cover only % of taiwan's population. premium shares among the government, employer and insured are varied according to the insured statuses. by the end of , Á m. people or % of the population were covered by the national health insurance programme. according to estimates by the pew research center's forum on religion & public life, Á % of the population in were folk religionists, Á % were buddhists and Á % christians. the remainder of the population was either religiously unaffiliated or followed other religions, including taoism. there were daily newspapers in with a circulation of Á m. and non-dailies with a circulation of Á m. the biggest circulation dailies are the liberty times and apple daily. in there were , , international visitors. receipts totalled us$ , m. the pop festival, spring scream, is held in april in kenting. xinjiang tianshan ( ), a mountainous site comprising four components covering , ha. and an important habitat for endemic and relic flora species, the grand canal ( ), a vast waterway system running from beijing to zhejiang, tusi sites ( ), the remains of tribal domains whose leaders were appointed by the central government as 'tusi', hereditary rulers of their regions from the th to the early th century, located in southwest china prime minister and president of the executive yuan: su tseng-chang vice premier: chen chi-mai. there are ministries under the executive yuan: culture; economic affairs; education; finance; foreign affairs; health and welfare; interior; justice; labour; national defence; science and technology minister of culture: cheng li-chiun examples include the mongolian and tibetan affairs commission; the mainland affairs council; the fair trade commission; the public construction commission; and the financial supervisory commission. some of these are headed by ministers without portfolio (see above). other commissions, councils and agencies are headed by: council of agriculture: chen chi-chung mainland affairs council: chen ming-tong. national communications commission: chan ting-i. ocean affairs council: lee chung-wei. overseas community affairs council: wu hsin-hsing. directorate general of personnel administration: shih ning-jye. transitional justice commission (acting): yang tsui. veterans' affairs council: chiu kuo-cheng china in world history chinese politics in the age of deng xiaoping china and the global political economy china: the rise of xi jinping the cambridge encyclopaedia of china the cambridge history of china. vols the politics of hong kong's reversion to china the european union and china the chinese economy under transition china this century the tragedy of liberation: a history of the chinese revolution china: a modern history china's deep reform: domestic politics in transition chinese capitalism deng xiaoping and the making of modern china the great chinese revolution - the politics of eu-china economic relations china's second continent: how a million migrants are building a new empire in africa china in transition: communism, capitalism and democracy sowing the seeds of democracy in china: political reform in the deng xiaoping era historical dictionary of the chinese cultural revolution how the chinese economy works the rise of modern china china: a macro history tombstone: the untold story of mao's great famine china's economy: what everyone needs to know all under heaven: a complete history of china chinese politics in the hu jintao era: new leaders, new challenges the people's republic of amnesia: tiananmen revisited chinese foreign policy in a changing world chinese economy in the s the politics of china: sixty years of the people's republic of china the party: the secret world of china's communist rulers. .-asia's reckoning: china, japan and the fate of us power in the pacific century china's war with japan, - : the struggle for survival social and political development in post-reform china age of ambition: chasing fortune, truth and faith in the new china a revolutionary life at the crossroads of post-communist modernisation: russia and china in comparative perspective a history of china wealth and power: china's long march to the twenty-first century mao's road to power: revolutionary writings - . vols china goes global: the partial power the chinese century: the rising chinese economy and its impact on the global economy, the balance of power, and your job the china-pakistan axis: asia's new geopolitics the chan's great continent: china in western minds eldest son, zhou enlai and the making of modern china china in the xi jinping era india's and china's recent experience with reform and growth critical issues in contemporary china making china strong tide players: the movers and shakers of a rising china other more specialized titles are listed under territory and popula-tion; tibet; agriculture . commissioner: ning jizhe information: the census and statistics department is responsible for the preparation and collation of government statistics. these statistics are published mainly in the hong kong monthly digest of statistics. the department also publishes monthly trade statistics, economic indicators and an annual review of overseas trade hong kong's transitions the politics of hong kong's reversion to china the end of hong kong: the secret diplomacy of imperial retreat the hong kong story the final years of british hong kong: the discourse of colonial withdrawal last post: the end of empire in the far east the politics of democratization in hong kong historical dictionary of hong kong and macau china: a political history of the british crown colony's transfer to chinese rule managing china's sovereignty in hong kong and taiwan macau, the imaginary city: culture and society, to the present taiwan statistical yearbook of the republic of china. annual. the republic of china yearbook. annual. taiwan statistical data book. annual. annual review of government administration the other taiwan: to the present day historical dictionary of taiwan national identity and status in international society taiwan's political re-alignment and diplomatic challenges managing china's sovereignty in hong kong and taiwan the shadow of china: political developments in taiwan since . national library: national central library key: cord- - es o authors: liao, qiuyan; cowling, benjamin j.; lam, wendy wing tak; fielding, richard title: factors affecting intention to receive and self-reported receipt of pandemic (h n ) vaccine in hong kong: a longitudinal study date: - - journal: plos one doi: . /journal.pone. sha: doc_id: cord_uid: es o background: vaccination was a core component for mitigating the influenza pandemic (ph n ). however, a vaccination program's efficacy largely depends on population compliance. we examined general population decision-making for ph n vaccination using a modified theory of planned behaviour (tbp). methodology: we conducted a longitudinal study, collecting data before and after the introduction of ph n vaccine in hong kong. structural equation modeling (sem) tested if a modified tpb had explanatory utility for vaccine uptake among adults. principal findings: among subjects who completed both the baseline and the follow-up surveys, % ( / ) reported being “likely/very likely/certain” to be vaccinated (intent) but two months later only . % ( / ) reported having received ph n vaccination. perception of low risk from ph n ( %) and concerns regarding adverse effects of the vaccine ( %) were primary justifications for avoiding ph n vaccination. greater perceived vaccine benefits (β = . ), less concerns regarding vaccine side-effects (β = − . ), greater adherence to social norms of vaccination (β = . ), anticipated higher regret if not vaccinated (β = . ), perceived higher self-efficacy for vaccination (β = . ) and history of seasonal influenza vaccination (β = . ) were associated with higher intention to receive the ph n vaccine, which in turn predicted self-reported vaccination uptake (β = . ). social norm (β = . ), anticipated regret (β = . ) and vaccination intention (β = . ) were positively associated with, and accounted for % of variance in vaccination planning, which, in turn subsequently predicted self-reported vaccination uptake (β = . ) accounting for % of variance in reported vaccination behaviour. conclusions/significance: perceived low risk from ph n and perceived high risk from ph n vaccine inhibited ph n vaccine uptake. both the tpb and the additional components contributed to intended vaccination uptake but social norms and anticipated regret predominantly associated with vaccination intention and planning. vaccination planning is a more significant proximal determinant of uptake of ph n vaccine than is intention. intention alone is an unreliable predictor of future vaccine uptake. influenza contributes significantly to worldwide morbidity and mortality [ ] . periodically, influenza viruses mutate into antigenically-different strains leading to global pandemics [ ] . the influenza pandemic (ph n ) was caused by a triple reassortment of human, swine and avian influenza viruses [ ] . vaccination is the most effective intervention for preventing influenza [ ] and a core part of national pandemic plans for pandemic mitigation. lead times of at least months in producing a vaccine against a novel strain means that while vaccines may be unavailable in time to prevent the first wave of a pandemic [ , ] , effective public uptake of a vaccine may mitigate subsequent waves [ ] . significant health promotion activities regarding influenza prevention have been prominent in hong kong since well before the onset of ph n , arising largely from the severe acute respiratory infection (sars) epidemic and a/h n bird flu outbreaks. seasonal influenza vaccination is widely promoted each year. hong kong's ph n epidemic started on june , peaking in september, and by early november had petered out ( figure ). by the end of december , the hong kong government had recorded , human ph n cases [ ] in a population of , million. to minimize any potential second wave, significant televised and other publicity was given to the launch of a ph n vaccination programme on december , initially for five priority groups: healthcare workers, persons with chronic illness and pregnant women, children aged months to years, adults aged years or above, and pig farmers and slaughtering industry personnel [ ] . on january ph n vaccination was extended to the general public. the vaccination was free for priority group members [ ] , but cost hk$ - (us$ - , - . % of hong kong's median monthly income of hk$ , / us$ , /j ) per dose for the general population. a study in july of respondents projected that vaccine uptake would be influenced by end-user cost, with %, of hong kong's general population being ''highly likely'' to take up ph n vaccine if free, and % if costing hk$ - (us$ [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ , ] . from november onwards, television, radio, newspaper and official websites strongly encouraged priority groups to have ph n vaccination [ ] . however, the hong kong government did not make recommendations for the general population, who were asked to judge for themselves whether to be vaccinated or not. shortly after the vaccine launch for priority groups, local media prominently attributed several adverse events to ph n vaccination, including, a case of guillain-barre syndrome (gbs) diagnosed a week after ph n vaccination, reported on th january , and an intrauterine death (iud) weeks following the mother's vaccination, reported on th january ( figure ). in both cases local health agencies presented convincing evidence challenging the link between vaccination and the two adverse events but were largely ignored. retrospectively, a drop in ph n vaccination uptake among priority groups was observed [ ] . it seems probable that the adverse media reports had impeded vaccination uptake among general population. we collected baseline data between - january, , immediately before ph n vaccine was made available to the general population and then two months later ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) march ) we recorded their reported vaccination status ( figure ) with the intention of modelling how general population decision-making regarding ph n vaccination might predict subsequent vaccine uptake. empirical studies have found that history of seasonal influenza vaccination [ , [ ] [ ] [ ] [ ] , perceived risk of pandemic influenza [ , [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] , worry [ , , , ] , and attitudes towards vaccine, such as vaccine efficacy and side-effects [ , , , [ ] [ ] [ ] were significantly associated with intention to receive a vaccine against the influenza pandemic. this is consistent with the findings related to determinants of vaccination against seasonal influenza [ ] [ ] [ ] [ ] [ ] . however, there are some common and significant limitations to these empirical studies. first, all except one [ ] relied on vaccination intention to predict the actual vaccination uptake. in one study, since only a few respondents reported having received the ph n vaccine, the authors combined those intending to get vaccinated with those who had already received the vaccine into one ''intending'' group and examined factors associated with this 'vaccination intention' [ ] . this is problematic because factors associated with vaccination intention and actual vaccination receipt probably differ. moreover, the reliability of intention as a predictor of actual behavior remains controversial. harris et al. found that only about half of ''intending'' recipients of seasonal influenza vaccination actually take it and almost all those who do not intend to take it remained unvaccinated [ ] . moreover, most studies conducted before the pandemic occurred or before the vaccine was available [ , , [ ] [ ] [ ] [ ] , ] of dutch respondents reported intending to take ph n vaccination prior to or at the onset of the (potential) pandemic phase, respectively [ ] . similarly, in hong kong % of respondents in july reported being ''highly likely'' to receive ph n vaccine if offered for free [ , ] . however, by the time vaccination became available intention appeared much lower with only - % of study respondents in france and in turkey intending to take the ph n vaccine [ , ] . second, all the studies are cross-sectional rather than longitudinal; none assessed subsequent actual vaccination status. thus, although associations have been identified, there is no way to infer causality. third, most of the studies are atheoretical. although some of the studies developed their study questions based on theoretical framework such as hbm [ , , ] , none have conducted model analysis and evaluated the model fit. therefore, due to these three reasons, there remains a significant concern about how valid such results are and a significant knowledge gap about how the observed pattern of influences could be explained. a major limitation of previous empirical studies [ , [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] , ] is failure to accommodate the intention-behaviour gap. although several behavioral theories such as protection motivation theory (pmt) [ , ] , theory of reasoned action (tra) [ , ] and theory of planned behaviour (tpb) [ , ] propose that intention is the proximal determinant of behaviour, intention does not necessarily translate into actual behaviour. empirical studies of the intention-behavior relationship showed that intention had a medium effect (a correlation of , . - . ) on behavior [ ] [ ] [ ] , but a recent review including experimental studies found that a medium-to-large change in intention induced by manipulated interventions caused only a small-to-medium change in behavior [ ] , where an effect size of . is medium and one of . is small [ ] . sheeran found that about % of those intending to take action fail to act [ ] , consistent with harris et al's findings [ ] . factors that are prime contenders to moderate/ mediate the relationship between intention and behaviour include behavioural control/efficacy, action planning and anticipation of consequences [ ] [ ] [ ] . perceived behavioural control/self-efficacy. the tpb is an extension of the tra incorporating the concept of perceived behavioural control (pbc) as an intervening variable predicting both intention and also actual behavioural change directly [ , ] . the direct effect of pbc on actual behavioural change partly explains why not all intention translates into behaviour. previous reviews suggested that intention-behaviour relationships could be moderated by perceived behavioral control, with higher levels of perceived behavioural control improving prediction of intention on behaviour [ , ] . although some researchers suggested that pbc differs from self-efficacy because selfefficacy emphasized perceived internal control more while pbc also considers external control factors [ ] , a systemic review on the efficacy of tbp found that pbc and self-efficacy had comparable effects on intention and behaviour [ ] . despite being a dominant theory of behavioural change, because the tpb is limited in predicting behaviour we sought to enhance its predictive power by replacing pbc with self-efficacy and incorporating enhanced social effects to accommodate external control factors. implementation of intention/planning. implementation of intention, termed ''planning'', is a potentially important factor facilitating translation of intention into behaviour [ , , , ] . planning is specific to situations (e.g., when, where, and how) within which one will perform the behaviour [ ] . it activates the situational context for goal attainment and thereby makes the goal become more accessible [ , ] . a meta-analytic review showed that implementation of intention as planning consistently caused a medium-to-large effect on behavioural change [ ] . anticipated regret. anticipated regret is the expectation of feeling regret or upset if one does or does not conduct certain behaviours. anticipated regret has been found to be a strong predictor of vaccine uptake against seasonal influenza [ , ] , playing the lottery [ ] and exercise [ ] . anticipated regret might also moderate the intention-behavior relationship: the higher anticipated regret for inaction, the better the prediction of intention on behaviour [ , ] . a robust theoretical framework comprehensively explaining behavior change that elucidates population decision-making for health protective and promoting behaviour has long been sought. as the main contender, the tpb explains , % of variance in health behavioural change related to addictive behaviour, automobile-related behaviours, clinical and screening behaviour, eating behaviour, exercising behaivour, hiv/aids-related behaviour and oral hygiene behaivour [ ] . the standard version of tpb proposes that attitudes towards the behaviour, subjective norm and pbc predict behavioral intention while intention and pbc predict the actual behavioural change [ , ] . additional predictors that significantly improve the model's predictive power are needed [ ] . two previous studies have examined modified versions of tpb to predict vaccination uptake against seasonal influenza [ , ] . one study used tpb plus two additional factors: influenza vaccination history and anticipated regret, to predict intention to receive vaccine against seasonal influenza among elderly from social clubs [ ] : vaccination history and anticipated regret respectively accounted for an additional . % and . % of total variance in influenza vaccination intention [ ] . however, again the study was cross-sectional and actual vaccination uptake was not assessed. a second study of healthcare workers [ ] adopted an extended version of tpb that included additional elements of anticipated regret, moral norm, descriptive norm and professional norm. the study found that controlling for the original tpb variables, moral norm and anticipated regret were significant determinants of actual receipt of seasonal influenza vaccine [ ] . the study provides useful information for future application of the extended version of tpb. however, since the study was conducted among healthcare workers, some of the variables such as moral norm and professional norm which emphasize obligation and professional convictions may not be applicable among the general population. factors influencing ph n vaccine uptake at the later stage of a pandemic might be more cognitively driven unlike behavioral responses during the early stage of a pandemic which might be more affect driven [ ] . therefore, taking into account prior work on seasonal influenza vaccination uptake [ , ] , extending the tpb could provide theoretical utility for understanding public decision on taking ph n vaccination. starting with tpb and existing literature, we therefore built a conceptual model of public decision-making for ph n vaccination ( figure ). in addition to the original tpb components, seasonal influenza vaccination history, anticipated regret and vaccination planning were included in the model. the model proposed that attitudes towards vaccination (perceived benefits of ph n vaccination and concerns regarding possible adverse effects of ph n vaccination), perceived social pressures from significant others and other people around regarding ph n vaccination (social norms regarding ph n vaccination), perceived self-efficacy in taking vaccination (perceived self-efficacy), anticipated regret for not taking the ph n vaccination (anticipated regret) and seasonal influenza vaccination history would predict vaccination intention, which in turn predicts vaccination planning and future vaccination uptake; anticipated regret and perceived self-efficacy could also predict vaccination status directly; finally, vaccination planning was proposed to bridge the intention-behavior gap and predict vaccination status directly ( figure ). we conducted a longitudinal study of influences on ph n vaccination behaviour in hong kong to test this model ( figure ) , and subsequently followed up participants to record their selfreported receipt of ph n vaccine. in this study, we aimed to answer the following research questions: how well does intention predict future uptake of ph n vaccine? does vaccination planning mediate the relation between intention and future vaccination uptake? and do the original tpb components and the additional components (extended social norms, anticipated regret and seasonal influenza vaccination history) contribute to peoples' decisions on vaccination uptake? the study obtained ethics approval from the institutional review board of the university of hong kong/hospital authority hong kong west cluster. written informed consent was waived by the irb because all the data were analyzed anonymously, but verbal consent was obtained from all the subjects before the interview started. hong kong has % landline telephone penetration, local calls are free and telephone interviews are common and representative methods of survey data collection [ ] . we conducted main cross-sectional telephone surveys of psychological and behavioural responses to the first wave of the influenza a/h n pandemic in hong kong from april through november (the parent study) [ ] in order to monitor these variables. as an extension, the present study re-contacted subjects from some of these surveys and sought to understand public decision-making regarding ph n vaccine uptake for mitigating the potential second wave of the pandemic. between - january, a baseline assessment for the present study was performed, immediately prior the local ph n vaccination campaign extending to the general community (vaccination for high risk groups started from december , ), and we again contacted participants for follow-up two months later, between - march . sample size determination. we estimated that a sample of at least was required to achieve % power at an a = . to reject a model of the specified complexity ( figure ) if the model fit index root mean square error of approximation (rmsea) exceeded . [ , ] . to allow for a response rate , % in the follow-up and the baseline surveys, we need to target at least , subjects in the baseline survey. subject selection and inclusion criteria. a flow chart showing subject selection is provided in figure . a total of , subjects participated in the parent study [ ] . all these subjects were cantonese-speaking adults (aged$ ) selected within households using a kish grid methodology, who were capable of and willing to answer a telephone interview. additional details about inclusion criteria are available elsewhere [ ] . respondents in the th , - th surveys of the surveys comprising the parent study who, in the parent study agreed to be re-contacted and who had not received ph n vaccine were invited to complete the baseline assessment for the present study. these five surveys (the th , - th surveys) were selected because participants in these surveys had not had any follow-up contact either in the parent study or otherwise. this minimizes interview fatigue thereby improving response rates. these surveys were all of a comparable sample size, between , - , [ ] . the five selected surveys were conducted between july and october , , and generated a representative [ ] pool of , respondents of whom . % ( , / , ) gave consent for further contact. from a list of the , subjects who agreed to be re-contacted, , calls were randomly selected and successfully made by a university telephone polling organization. unanswered calls were tried at least four times at different hours and weekdays before being replaced by new numbers. finally, a total of , ( %, , / , ) respondents agreed to participate in the baseline survey. of these ( %, / , ) reported already having received ph n vaccination and were therefore excluded as ineligible, leaving , respondents who completed baseline interviews. the interview questionnaire for the baseline survey was derived from literature review, our previous cross-sectional surveys [ ] and the theoretical framework constructed for this study (figure ). specialists in health psychology, statistics, infectious disease and public health jointly determined the measures comprising the final questionnaire, guided by the need to maintain low assessment load and parsimony to ensure good response rates. the finalized questionnaire consisted of five sections: section addressed respondents' self-rated health and their experience of influenzalike illness in the past six months; section addressed risk perceptions regarding ph n ; section addressed perceived trust in information related to ph n and ph n vaccination from different information sources; section addressed attitudes, beliefs and social norms regarding ph n vaccine/vaccination, vaccination intention and planning; section addressed key respondent demographics. overall, the baseline assessment consisted of questions, which took less than minutes to complete. other demographic data were obtained from the parent study [ ] . prior to baseline assessment for the present study, subjects were reminded of their prior participation and that they had agreed to participate in a further study. the study was introduced as a survey of attitudes towards swine flu vaccination. we sought their willingness to participate. those agreeing were asked about their vaccination status. subjects who reported that they had already received ph n vaccination were excluded. the remaining interview was performed. a follow-up survey was conducted months later wherein respondents were reminded of the earlier survey and asked about their vaccination status and reasons for having had or not having vaccination. all the data were collected through telephone interview in both baseline and follow-up surveys. the measures comprising the study instruments were used to build the conceptual model ( figure ) and are described below and in table . perceived benefits of ph n vaccination, and, concerns regarding adverse effects of ph n vaccination. these two constructs assessed attitudes towards ph n vaccination. perceived benefits of ph n vaccination was assessed by measuring agreement on five-point ordinal scales (from ''strongly disagree'' to ''strongly agree'') with three statements (table ) . a cronbach's alpha (a) of . indicated an acceptable internal consistency for this scale and these two items were treated as the indicators of a latent scale (perceived benefits of ph n vaccination). concerns regarding adverse effects of ph n vaccination were assessed by measuring agreement, using fivepoint scales, with two statements. the cronbach's a for these two items was . , considered acceptable by some researchers [ ] , though clearly less than desirable. we therefore treated the items as reflecting a latent variable (concerns regarding adverse effects of ph n vaccination). social norms regarding ph n vaccination. while tbp considers the influence of solely coercive social pressure from significant others to perform a behaviour, previous studies suggest that it is also important to consider the generalized tendency to adopt behaviours demonstrated by others encountered in daily life for imitative reasons [ , ] . we use the term social norms rather than subjective norm to represent these broader coercive and imitative social influences. social norms were assessed by agreement on a -point scale with two statements. the internal consistency for these two items was weaker, with a = . , which suggests each item appropriately measures different social influences. we initially incorporated these items separately in the structural equation model but except for the path weights dividing almost equally between the two items, no difference was otherwise seen. we therefore retained them as indicators of a combined latent construct in the model for purposes of model parsimony [ ] . anticipated regret. anticipated regret was assessed with two statements asking about respondents' likelihood of feeling regret. responses of these two items were on a -point categorical scale (from ''definitely not'' to ''certain''). the internal consistency a for these two items was . . the two items were used to indicate the latent variable ''anticipated regret'' in the modeling analysis. perceived self-efficacy. one item was used to measure selfefficacy, asking about respondents' agreement on a -point scale with the statement ''i am confident that i can go independently to get human swine flu vaccination''. a standard scale of self-efficacy was not adopted to minimize assessment load. however, a single item for self-efficacy has been shown elsewhere to have validity in predicting behavioural change [ , ] . seasonal influenza vaccination history. respondents were asked whether they had received any seasonal influenza vaccination in the past three years (yes/no/don't know). vaccination intention. respondents were asked how likely it was that they would get vaccinated against ph n during the winter flu season, using a -point likert scale (from ''definitely not'' to ''certain''). vaccination planning. we measured vaccination planning by assessing respondents' agreement on a -point scale with three statement items, such as ''i have planned when and where to get my human swine flu vaccination this winter''. the internal consistency a for these three items was . , though less than the most common acceptable level of above . , remaining at the minimal acceptable level (a ranged between . - . ) of reliability for preliminary research [ ] . these items were also treated as indicators of a latent variable for modeling purposes. reported vaccination uptake. in the follow-up survey, respondents were asked to confirm if they had received ph n vaccine within the past three months. respondents were also asked to indicate their major reasons for having or not having taken the ph n vaccination using open-ended questions. multiple reasons could be given by each respondent. we first compared demographic differences between follow-up and lost-to-follow-up respondents with pearson chi-square test while demographic differences of the respondents who completed both the baseline and follow-up survey and the general population [ ] were assessed using cohen's effect sizes [ ] . proportions were calculated to describe patterns of vaccination intention, reported vaccination uptake, and major reasons for taking or not taking ph n vaccination. structural equation modeling was then applied to examine the determinants of ph n vaccination, vaccination intention and vaccination planning based on the extension of tbp. mplus . for windows (muthén & muthén, - was employed because the model comprised dichotomous (vaccination status) and ordinal (vaccination intention) outcome variables. before testing the full structural model, zeroorder correlations between the measures of related constructs were calculated. confirmatory factor analysis was performed to assess the adequacy of the measurement model including perceived benefits of ph n vaccination, concerns regarding adverse effects of ph n vaccination, social norms regarding ph n vaccination, anticipated regret and vaccination planning. to test the full structural model, all variables were entered into the model simultaneously. mean and variance adjusted weighted least squares estimation was applied to evaluate the standardized parameters (beta, b). since chi-square test is very sensitive to sample size and non-normally distributed data, several other model fit indices were evaluated including the comparative fit index (cfi), the tucker lewis index (tli), and rmsea. a cfi. . and tli. . indicates a good fit. rmsea less than . and one ranging between . - . respectively indicate a good and acceptable model fit [ ] . misfitting models were respecified guided by theoretical soundness and modification indices [ ] . missing proportions ranged from . % for seasonal flu vaccination history to . % for the item ''i have planned when and where to get my ph n vaccination this winter''. there was no missing data for reported vaccination uptake. missing data were handled with multiple imputation [ ] . of the respondents who completed the baseline assessment, / ( %) respondents agreed to participate and completed the march follow-up survey (figure ). demographic characteristics of respondents in the baseline and followup surveys are shown in table . compared to respondents completing both baseline and follow-up surveys, respondents lost to follow-up were younger (x = . , p = . ) and more likely to be single (x = . , p, . ). overall, the low cohen effect sizes (, . ) showed that the demographics of respondents who completed both the baseline and follow-up surveys were comparable to those of the general population of hong kong [ ] . of the , respondents who completed the baseline survey, % ( / , ) reported that they would ''definitely not'' take ph n vaccination during the winter flu season; % ( / , ) reported being ''very unlikely/unlikely'' to take it; % ( / , ) reported their ph n vaccination likelihood as ''evens'' ( : /equal likelihood); and only % ( / , ) reported vaccination likelihood as ''likely/very likely/certain''. within the subset of / , respondents who completed both baseline and follow-up surveys, % ( / ) had reported at baseline that they would be ''likely/very likely/certain'' to receive ph n vaccination. however, in the follow-up survey, only / ( . %) respondents reported having received ph n vaccination in the intervening period, of whom had reported being ''likely/very likely/certain'' to receive ph n vaccination at baseline. reporting higher intention to receive ph n vaccination in the baseline was associated with greater likelihood to vaccinate by follow-up (fisher's exact test, x = . , p, . ). the respondents who reported taking ph n vaccination gave the major reasons for deciding on vaccination as follows: three choose vaccination because of the 'high risk of swine influenza' characterized by statements like ''swine flu is serious'', ''i am worried that swine flu will become more serious'', and ''i feel vulnerable to swine flu''; two reported that their decision was due to 'doctors' advice' and two reported 'belief of the vaccine efficacy'. other reasons provided by one respondent only were 'belief in the vaccine's safety', 'government recommendation', 'convenient availability', and 'protection of patients'. reasons for not having vaccination given by the respondents who did not receive ph n vaccination ( figure ) were, most frequently 'low risk of or from swine influenza' ( / , %) and 'concerns regarding adverse effects of the vaccine' ( / , %). around % ( / ) of the respondents reported both 'low risk of/from swine influenza' and 'concerns regarding adverse effects of the vaccine'. table for the final full structural model (figure ), two additional paths were added and estimated based on the modification indices including a path from social norms to vaccination planning and path from anticipated regret to vaccination planning while the path from perceived self-efficacy to vaccination and the path from anticipated regret to vaccination were removed, coefficients for these two paths being nonsignificant and too small to be meaningful. the final model indicated a good fit with cfi = . , tli = . and rmsea = . ( figure ) . the model showed that respondents perceiving greater ph n vaccination benefits (b = . ), less concerns regarding vaccine adverse effects (b = . ), greater sensitivity to social norms b = . ), higher anticipated regret if not vaccinated (b = . ), higher perceived self-efficacy in taking ph n vaccination (b = . ) and receiving seasonal influenza vaccination in the past three years (b = . ) reported greater intention to take ph n vaccination, and accounted for % of variance in vaccination intention scores. greater adherence to social norms (b = . ), higher vaccination intention (b = . ) and higher anticipated regret (b = . ) were associated with more vaccination planning, together accounting for % of variance in vaccination planning. both vaccination intention (b = . ) and vaccination planning (b = . ) significantly predicted actual ph n vaccination, accounting for % of variance in ph n vaccination ( figure ). the world health organization recommended a stepwise use of ph n vaccines for protecting people against the ph n influenza pandemic in july [ ] . however, a vaccination program's efficacy largely depends on the public's compliance. our study found that only % of , subjects reported having received ph n vaccination and of , subjects remaining unvaccinated, only % reported intending (being likely/very likely/certain) to take the ph n vaccine. two months later in the follow-up survey, an even smaller proportion, . % of the respondents who completed both the baseline and follow-up survey reported having been vaccinated against ph n . perceived low risk of ph n and concerns regarding vaccine-related adverse effects were the two most frequently cited reasons for refusing the vaccination. the extended tpb model suggests that both the original tpb components and the additional components contribute to people's decisions on vaccination uptake but that social norms and anticipated regret for not taking vaccination were the strongest determinants of vaccination intention and vaccination planning. finally vaccination planning partially-mediated the relation between intention and reported vaccination uptake. compared to previous studies, vaccination intention was much lower in our study than that found in surveys conducted prior to the influenza pandemic [ ] or before the vaccine was available [ ] , but was comparable to the findings of surveys conducted in france [ ] and turkey [ ] after ph n vaccination programmes were launched there. an earlier hong kong study that relied on expressed intent to predict vaccination uptake [ ] failed to accurately predict the subsequent meager population uptake of ph n vaccination by, at best, an order of magnitude [ ] , suggesting that intention alone is insufficient for predicting future vaccination uptake, consistent with empirical findings in other areas [ , ] . despite predictions that intended ph n vaccination uptake would decline if there was insufficient data on novel vaccine safety and efficacy [ ] , safety issues were not the predominant barrier to vaccination in the present study. while % of our study respondents who remained unvaccinated cited vaccine safety concerns, despite good evidence that the vaccine is effective with a risk profile similar to that of seasonal influenza vaccine [ ] , almost twice as many, %, cited 'low risk of/from swine influenza' as their reason for not getting vaccinated, suggesting that these respondents felt no advantage would be gained by vaccination. around % of respondents, cited both 'low risk of/ from swine influenza' and 'concerns regarding adverse effects of vaccine' as the reasons for not getting vaccinated, seemingly adopting a risk-benefit approach to vaccination decision-making. however, in the setting of low influenza risk, with the reports of vaccine related adverse events in the media after the vaccine was available for the priority groups (figure ) , people may shift their perceived risks away from influenza and towards vaccination, suggestive of availability bias (risk distortion by easily recalled events) [ ] . we believe that perceived vaccine risk would become progressively less of a barrier to vaccination as perceived influenza risk increases, and vice versa. moreover, despite recent reports that hong kong residents would be sensitive to vaccination pricing when considering whether to vaccinate [ , ] , only . % of our respondents cited high vaccine cost as the reason for rejecting vaccination. major reasons for taking ph n vaccination corresponded to reasons for not taking it, with perception of ph n risk most frequently cited. however, the few respondents receiving ph n vaccination prohibited meaningful comparison. the extended version of tpb model fits well to the survey data. the model showed that an expanded social norms and anticipated regret accounted for most of the variance in vaccination intention, rather than the more core elements of tpb. in turn, social norms independently accounted for more than twice the variance in vaccination planning than did intention, and vaccination planning accounted for more variance in vaccination uptake than did intention. thus it seems that social norms comprise the major influences on vaccination uptake through modifying vaccination intention and planning. a meta-analytic review of tpb efficacy concluded that the tpb variable subjective norm (perceived coercive social pressure from significant others) weakly predicted intention compared to other tpb components, mainly due to poor measurement [ ] . ''descriptive norm'' (perception of what other people do, imitation or conformity behaviour) is reportedly a more important predictor for intention [ , ] . here we combined table . correlations, means, standard deviations, and standardized factor loadings for the measurement model. measures of subjective and descriptive norms, treated as a latent variable (social norms), because they were found to have much the same predictive direction and weight. multiple item measures of norms should have better predictive power than single item measures [ ] . this model importantly informs public health approaches to population behaviour during respiratory epidemics. first, information uncertainty or untrustworthiness, for example regarding vaccine safety, is likely to prompt people look to others for their cues to action: the social environment, namely what other people believe and do powerfully influences decisions to action [ , ] . people often tend to imitate others, so establishing a ''vaccination trend'' may help uptake. for example, it could be effective to encourage those who remain unvaccinated with feedback from vaccinated peers and by providing an updated total of numbers vaccinated. what the general public think and do may prove to be as influential as information from scientists or health professional [ , ] . second, encouraging uptake of a new vaccine will be problematic if the associated threat element is low, irrespective of vaccine pricing, particularly for novel and untested vaccines. vaccine safety and efficacy data should be provided wherever possible at all levels including through health-care providers, media and the general public. to effectively communicate the risk and benefit of a novel vaccine, it is important to establish an effective surveillance system to monitor vaccination progammes and rapidly respond to any reported adverse events [ ] . the media have an important influence and both reactionary and opinionated news items should be recognized as potentially detrimental to vaccination uptake. in particular, the need to develop stories that generate revenue increasingly overrides balanced reporting in contemporary media. hence risk amplification remains a problem. public health agencies need to improve their liaison with influential media outlets to minimize this, where possible. third, omission bias, a phenomenon where people view vaccination as more risky than remaining unvaccinated, could be a barrier for vaccination [ ] . omission bias arises when there is anticipation of greater regret about adverse effects of vaccination, if taken, than the regret about being infected with influenza if vaccination is rejected [ ] . therefore, social marketing emphasizing the far greater likelihood of regret for consequences due to refusing vaccination than the regret over an improbably low adverse event due to taking vaccination may help to reduce this bias. for example, previous studies found that simply asking two questions about feeling regret for inaction could increase respondents' intention to play a lottery or do exercise [ , ] . finally, vaccination planning is a key intervening variable between vaccination intention and actual vaccination. this is to be expected given that it is more proximal to actual behaviour than intention is. in those who may be undecided, interventions facilitating planning may prompt action. this could include suggesting where, when and how to get vaccination, improving and publicizing accessibility of vaccination centres and opening times. even so, intention and planning explained only % of the variance in the reported vaccination behaviour, suggesting that other factors, such as intention stability [ ] , influencing vaccination behaviour await identification. study limitations include baseline attitudes/beliefs, vaccination intention and planning being measured at the same time point, prohibiting exploration of causality in observed associations. some study measures were constrained due to length of telephone interviewing, and while sub-optimal were necessary methodological compromises. although most researchers recommended cronbach's a of . as the minimal acceptable for internal consistency of multi-item scales, others accept . or . - . for preliminary research as the cut-off point [ ] . other than dimensionality concerns, lower a can reflect too few items comprising the putative scale [ ] . this is more likely for complex variables, such as social norms which have a broad spectrum of elements. though less than perfect, measurement errors can be reduced by incorporating the items as a latent variable in sem [ ] , an approach we adopted. additionally, collinearity between exogenous indicators, such as social norms and perceived benefit can be potentially problematic, perhaps lowering the accuracy of sem estimation. however, since high associations between measures of the constructs were not observed (table ) then collinearity-related error is probably small [ ] . despite being randomly selected for the parent study, subjects of this study were not randomly selected from the general population, although demographics suggest the current sample is comparable to the hong kong general population [ ] (table ). moreover, subject recruitment was based on voluntariness and all data were selfreported. all could cause social desirability and selection bias, so caution is needed before extrapolation to the general population. also refusal at follow-up could have influenced patterns of responses. our study examined public decision-making regarding a novel influenza pandemic vaccine. our findings may not apply to vaccination against seasonal influenza due to numerous differences in beliefs towards the vaccination. for example, although perceived low risk remains the major reasons for refusing vaccination against seasonal influenza as in our study, vaccine safety is seldom cited as a barrier [ , ] whereas we found that about one third of respondents had vaccine safety concerns. cultural differences in influenza and vaccination-related beliefs are possible [ ] , but these differences may gradually diminish with the increasing identical news information available through the three dominant news agencies and common public health strategies being increasingly universal. related stories, such as use of preservatives and adjuvants in vaccine manufacture may enhance knowledge and reduce trust in product safety [ ] . the role of media remains much under-researched in this regard. finally, data was insufficient to reliably report the reasons for ph n vaccination uptake among the population. nonetheless, compared with other cross-sectional studies [ , [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] , the longitudinal design of this study strengthens understanding of influences on population decision-making for pandemic influenza vaccination uptake and represents a step forward in this area of research. this study is novel in linking theoretically derived, vaccination-related cognitions to subsequent influenza vaccination behaviour, and exemplifies that within the hong kong chinese culture, social norms and action planning are far more influential than intention in predicting vaccination behaviour. the global impact of influenza on morbidity and mortality evolution and ecology of influenza a viruses emergence of a novel swine-origin influenza a virus (s-oiv) h n virus in humans efficacy and effectiveness of influenza vaccination pandemic influenza vaccine manufacturing process and timeline public health. will vaccines be available for the next influenza pandemic preparing for the second wave: lessons from current outbreaks number of notifications for notifiable infectious diseases human swine influenza vaccination programme human swine influenza vaccination acceptability of a/h n vaccination during pandemic phase of influenza a/h n in hong kong: population based cross sectional survey factors in association with acceptability of a/h n vaccination during the influenza a/ h n pandemic phase in the hong kong general population publicity plan for human swine influenza vaccination programme statistics on human swine influenza vaccinations press releases determinants of intention to get vaccinated against novel (pandemic) influenza a h n among health-care workers in a nationwide survey does receipt of seasonal influenza vaccine predict intention to receive novel h n vaccine: evidence from a nationally representative survey of u.s. adults factors in vaccination intention against the pandemic influenza a/h n influenza vaccination and intention to receive the pandemic h n influenza vaccine among healthcare workers of british columbia, canada: a cross-sectional study intent to receive pandemic influenza a (h n ) vaccine, compliance with social distancing and sources of information in nc low acceptability of a/h n pandemic vaccination in french adult population: did public health policy fuel public dissonance? public perceptions in relation to intention to receive pandemic influenza vaccination in a random population sample: evidence from a cross-sectional telephone survey risk perceptions, worry, or distrust: what drives pregnant women's decisions to accept the h n vaccine? which factors are important in adults' uptake of a (pre)pandemic influenza vaccine? why were turks unwilling to accept the a/h n influenza-pandemic vaccination? people's beliefs and perceptions about the swine flu outbreak and vaccine in the later stage of the epidemic demographic and attitudinal determinants of protective behaviours during a pandemic: a review relationship between intention of novel influenza a (h n ) vaccination and vaccination coverage rate the impact of communications about swine flu (influenza a h n v) on public responses to the outbreak: results from national telephone surveys in the uk influenza vaccine coverage rates and perceptions on vaccination in south korea influenza vaccination coverage rates in five european countries-a population-based cross-sectional analysis of two consecutive influenza seasons what factors affect influenza vaccine uptake among community-dwelling older chinese people in hong kong general outpatient clinics? emotions and preventive health behavior: worry, regret, and influenza vaccination risk perceptions: assessment and relationship to influenza vaccination do people who intend to get a flu shot actually get one? a protection motivation theory of fear appeals and attitude change cognitive and physiological processes in fear appeals and attitude change: a revised theory of protection motivation belief, attitude, intention, and behavior understanding attitudes, and predicting social behavior attitudes, personality and behavior the theory of planned behaivor the theory of planned behavior: a review of its applications to health-related behaviors efficacy of the theory of planned behaviour: a meta-analytic review intention-behavior relations: a conceptual and empirical review does changing behavioral intentions engender behavior change? a meta-analysis of the experimental evidence statistical power analysis for the behavioral sciences social foundataions of thought and action: a social cognitive theory implementation intentions: strong effects of simple plans implementation intentions and goal achievement: a meta-analysis of effects and processes augmenting the theory of planned behavior: roles for anticipated regret and descriptive norms acting on intentions: the role of anticipated regret determinants of older adults' intentions to vaccinate against influenza: a theoretical application determinants of influenza vaccination among healthcare workers situational awareness and health protective responses to pandemic influenza a (h n ) in hong kong: a cross-sectional study community psychological and behavioral responses through the first wave of pandemic (h n ) in hong kong power analysis and determination of sample size for covariance structure modeling principles and practice of structural equation modeling a meta-analysis of cronbach's coeffient alpha efficacy of an extended theory of planned behaviour model for predicting caterers' hand hygiene practices combining behavioral theories to predict recycling involvement an outbreak of the severe acute respiratory syndrome: predictors of health behaviors and effect of community prevention measures in hong kong, china psychosocial factors influencing the practice of preventive behaviors against the severe acute respiratory syndrome among older chinese in hong kong main tables of the population census. hong kong: government of the hong kong sar analyzing incomplete political science data: an alternative algorithm for multiple imputation who recommendations on pandemic (h n ) statistics on human swine influenza vaccinations as at safety of pandemic (h n ) perception of risk journey through an epidemic: some observations of contrasting public health responses to sars an evaluation of a belief hiv/aids prevention intervention for college students using normative feedback and goal setting reducing the risk of hiv transmission among adolescents in zambia: psychosocial and behavioral correlates of viewing a risk-reduction media campaign vaccine safety: risk communication-a global perspective omission bias and vaccine rejection by parents of healthy children: implications for the influenza a/h n vaccination programme omission bias and pertussis vaccination what is coefficient alpha? an examination of theory and applications multicollinearity and measurement error in structural equation models: implications for theory testing the - influenza pandemic: effects on pandemic and seasonal vaccine uptake and lessons learned for seasonal vaccination campaigns addressing parents' concerns: do vaccines contain harmful preservatives, adjuvants, additives, or residuals? we thank the hku public opinion programme for assistance in administering the telephone survey. we thank diane ng for coordinating the data collection and data management. analyzed the data: ql. contributed reagents/materials/analysis tools: ql bjc wwtl rf. wrote the paper: ql bjc wwtl rf. key: cord- - b quuqx authors: zhou, y.; ng, d.m.w.; seto, w.-h.; ip, d.k.m.; kwok, h.k.h.; ma, e.s.k.; ng, s.; lau, l.l.h.; wu, j. t.; peiris, j.s.m.; cowling, b. j. title: seroprevalence of antibody to pandemic influenza a (h n ) among healthcare workers after the first wave in hong kong date: - - journal: journal of hospital infection doi: . /j.jhin. . . sha: doc_id: cord_uid: b quuqx summary during the first wave of an influenza pandemic prior to the availability of an effective vaccine, healthcare workers (hcws) may be at particular risk of infection with the novel influenza strain. we conducted a cross-sectional study of the prevalence of antibody to pandemic influenza a (h n ) (ph n ) among hcws in hong kong in february–march following the first pandemic wave. sera collected from hcws were tested for antibody to ph n influenza virus by viral neutralisation (vn). we assessed factors associated with higher antibody titres, and we compared antibody titres in hcws with those in a separate community study. in total we enrolled hcws. among hcws who did not report receipt of ph n vaccine, % had antibody titre ≥ : by vn. there were no significant differences in the age-specific proportions of unvaccinated hcws with antibody titre ≥ : compared with the general community following the first wave of ph n . under good adherence to infection control guidelines, potential occupational exposures in the hospital setting did not appear to be associated with any substantial excess risk of ph n infection in hcws. most hcws had low antibody titres following the first pandemic wave. prior to the availability of an effective vaccine, healthcare workers (hcws) may have faced particular risk of pandemic influenza a (h n ) (ph n ) infection. infection of hcws during a pandemic is of public health concern not only because of the impact of infection and illness on the hcws themselves but also because hcws have frequent contact with patients who could be predisposed to serious illness if infected with influenza, and substantial rates of absenteeism among hcws could have adverse effects on the healthcare system. in the institute of medicine and the centers for disease control and prevention recommended that all healthcare workers who would have contact with suspected or confirmed ph n patients should use n respirators. recommended practice in hong kong followed world health organization (who) guidelines under which surgical masks should be routinely worn by all healthcare workers, standard droplet precautions should be implemented during contact with influenza patients, and greater precautions including face shields and n respirators used when performing aerosol-generating procedures. the first imported ph n case arrived in hong kong on april and, after sporadic imported cases through may, local transmission was identified in mid-june. the first wave peaked in september and had subsided by november. , ph n was a notifiable condition throughout the first wave, and laboratory-confirmed cases were notified including hcws, from a local population of million including hcws. the hong kong government provided ph n vaccine (sanofi pasteur) for five target groups including hcws starting december , and about % of local hcws had received influenza vaccine by march . the infection attack rate among hcws is likely to be greater than that suggested by the notification rate ( / , . %) because many symptomatic cases did not receive laboratory testing, while a fraction of ph n infections are subclinical. since few individuals aged < years had detectable antibody to ph n prior to the pandemic, e serological studies provide a straightforward way to infer infection attack rates. , we conducted a crosssectional study of ph n antibody among hcws in hong kong following the first epidemic wave. we recruited hcws between february and march in six public hospitals comprising the hong kong west cluster of the local hospital authority, with a total workforce of around hcws in one acute care teaching hospital and five non-acute hospitals. we established fixed study locations in each hospital, and participants were invited to attend our study site and participate in our study by open advertisement to all cluster employees. hcws were eligible to participate if they were hong kong residents and had worked in the cluster for at least one month. we aimed to recruit at least hcws who had not received ph n vaccine so that we could estimate the prevalence of antibody titre ! : to within ae . % overall and to within ae % within -year age groups. the study protocol was approved by the institutional review board of the university of hong kong/hospital authority hong kong west cluster. serum specimens collected from participants were kept in a refrigerated container at e c immediately after collection and delivered to the laboratory at the end of each working day for storage at e c prior to testing. sera were tested for antibody responses to a/california/ / (h n ) by a viral microneutralisation (vn) assay using standard methods. , because the vn assay was found to have greater sensitivity for ph n infection than haemagglutination inhibition (hai) in our previous study we used the vn assay as the primary serological test in this study. a titre of ! : was taken as the threshold for seropositivity because in a previous study conducted in the same laboratory around % of patients with confirmed infection reached a titre of ! : by vn at convalescence whereas few individuals had a titre ! : by vn before the first pandemic wave. a randomly selected subset of specimens plus all specimens from participants who reported laboratory-confirmed ph n infection were also tested by hai using standard methods. we compared the differences in the proportion of hcws with ph n antibody titre ! : between groups with c -tests or fisher's exact test. we compared age-specific proportions of hcws with ph n antibody titre ! : with antibody seroprevalence among blood donors determined from a separate community study also conducted after the first wave. we used logistic regression to explore factors associated with antibody titre ! : . factors that were statistically significant in univariate analyses were included in multivariate models. multiple imputation was used to allow for a small amount of missing data on some characteristics. a total of hcws were recruited; hcws who reported receipt of ph n vaccine were excluded from the following analyses. among the hcws who reported that they had not received ph n vaccine, ( %) had ph n antibody titre ! : by vn. in a random sample of / tested by hai, ( %) had antibody titre ! : . there was a significant difference in the proportion of hcws with antibody titre ! : by age, with greater proportion among younger hcws, and by occupation, with greater proportion among doctors compared with nurses (table i) . in a multivariate analysis, age remained significantly associated with an antibody titre ! : and hcws working in the emergency room had a marginally significant higher probability of antibody titre ! : (p ¼ . ) (table ii) . among the hcws, ( . %) reported laboratory-confirmed ph n infection during the first wave, and % ( % ci: e ) of those had antibody titre ! : by vn, and % ( % ci: e ) had antibody titre ! : by hai. among the hcws who did not report laboratory-confirmed ph n infection, % ( % ci: . e ) table iii shows the comparison of ph n antibody seroprevalence in hcws versus blood donors at the hong kong red cross involved in a separate community study. there was no statistically significant difference in seroprevalence by age between hcws and the community population in march apart from a marginally significant difference in hcws aged e years (p ¼ . ). in a multivariate logistic regression model for the hcw and community data combined (assuming that none of the community blood donors were hcws), the probability of antibody titre ! : varied significantly by age, but not by hcw status (or: . ; % ci: . e . ; p ¼ . ). the first wave of ph n infection occurred between july and november in hong kong. , the community infection attack rate in the first wave was estimated at around %, with much higher attack rates among children. in our study / ( . %) unvaccinated hcws reported laboratory-confirmed pandemic h n infection compared with an overall rate of % in hcws in hong kong, while . % of unvaccinated hcws had antibody titre ! : . assuming that the baseline seroprevalence in hcws was similar to the community, the estimated infection attack rate in hcws would have been around e % in different age groups (table iii) , suggesting that the majority of ph n infections in hcws were not laboratory-confirmed. among unvaccinated hcws, % of hcws who had pandemic influenza antibody titre ! : reported febrile influenza-like illness during the pandemic. whereas some hcws may have had antibody titre ! : prior to the pandemic, and others may have had a febrile illness not associated with influenza infection, these data are consistent with most ph n infections being symptomatic. therefore the who recommendation that hcws should withdraw from work while suffering acute respiratory illness appears to be a reasonable precaution to reduce the risk of nosocomial transmission. we did not identify statistically significant age-specific differences in seroprevalence in march between unvaccinated hcws and blood donors from the general community (table iii) , noting that vaccine coverage in the latter population was very low in march in hong kong. thus our data are not consistent with an increased risk of ph n infection in hcws, which is in agreement with previous data indicating no excess risk of pandemic influenza in hcws in singapore or seasonal influenza infection in hcws in germany. we also found that there was no significant difference in seroprevalence between hcws in an acute care hospital versus non-acute hospitals, between hcws who did or did not have contact with suspected or confirmed ph n patients, or by presence of school-age children at home (table i) . one study reported higher prevalence of ph n antibody in hcws in taiwan compared with that the general community, although age was strongly associated with seroprevalence, and age distributions differed between the hcw and community samples, possibly explaining the differences in seroprevalence. infection control procedures in hong kong followed the who guidelines. it is likely that the guidelines for the appropriate use of personal protective equipment were stringently adhered to following previous experiences with severe acute respiratory syndrome in as well as intensive control efforts from dedicated infection control teams. although we did not collect detailed data on adherence to infection control measures, another study reported that failure to comply with standard precautions such as wearing a surgical mask during contact with suspected influenza patients was associated with an increased risk of ph n infection. factors associated with a higher risk of antibody titre ! : among unvaccinated hcws included younger age and working in the emergency room, whereas other factors such as occupation (after adjustment for age), number of occupational contact with influenza patients, and seasonal influenza vaccination history were not significantly associated with risk of antibody titre ! : (tables i and ii) . younger hcws were more likely to have antibody titre ! : , consistent with higher population attack rates in younger age groups, although potentially confounded by differences in age-specific ability to mount antibody response to infection. as the first point of contact with most influenza patients in a hospital setting is the emergency room, it is plausible that hcws in the emergency room could face the highest and most frequent risk of infection e even though many patients with influenza-like illness are not admitted. in addition, hcws in the emergency room would tend to see patients earliest in their course of disease, when they might be most infectious. influenza vaccination is the best primary prevention measure against infection, and hcws are often one of the target groups to receive vaccine not only for their direct protection both in the healthcare setting as well as in the community, but also to indirectly protect patients against nosocomial transmission. , in hong kong, hcws were one of the target groups for ph n vaccine, but coverage was low following intense media coverage of a series of adverse events potentially associated with ph n vaccine. around % of hcws in our study reported receipt of one dose of ph n vaccine, compared with overall vaccine coverage of around % of hcws in hong kong. although our results suggest that following who guidelines for infection control was sufficient to prevent substantial excess risk of ph n associated with occupational exposures in a hospital setting, vaccination is still important for protection of hcws against infection in other settings. it is important to note several limitations of our study. first, we conducted a cross-sectional seroprevalence study following the first ph n wave, and we did not have baseline (pre-pandemic) data to enable us to infer accurately attack rates among hcws. analysis of serological data may misclassify the infection status of some individuals. however, few adults in hong kong had antibody to ph n at titre of ! : prior to the first wave (table iii) , whereas most individuals infected with ph n did go on to develop antibody titres ! : . second, although we did not observe any substantial excess risk of ph n infection in hcws compared with the general community, it is possible that a smaller excess risk did exist but may have been masked by community exposures in our study. larger and more detailed studies of hcws are certainly warranted to help understand the risk of nosocomial infection and the effectiveness of preventive measures. third, participants in our study were a convenience sample covering hcws in both acute and non-acute hospitals; a random sample would have been ideal albeit more difficult to implement with a high response rate. finally, we recruited hcws who were working in six public hospitals on hong kong island and our results may not generalise to hcws working in other regions of hong kong or local private hospitals and outpatient clinics. our data suggest that generally hcws in hospitals in hong kong, operating under the who infection control guidelines, did not have a higher risk of infection associated with their occupation compared with the general community. furthermore, following the first pandemic wave, most hcws did not have antibody titres at levels that would typically be considered protective against infection, since vaccine uptake was very low. requiring influenza vaccination for health care workers: seven truths we must accept prevention of nosocomial transmission of swine-origin pandemic influenza virus a/h n by infection control bundle the effective reproduction number of pandemic influenza: prospective estimation the infection attack rate and severity of pandemic influenza (h n ) in hong kong incidence of pandemic influenza a h n infection in england: a cross-sectional serological study cross-reactive antibody responses to the pandemic h n influenza virus comparative epidemiology of pandemic and seasonal influenza a in households effect of clinical and virological parameters on the level of neutralizing antibody against pandemic influenza a virus h n multiple imputation for missing data in epidemiological and clinical research: potential and pitfalls influenza a(h n ) seroconversion rates and risk factors among distinct adult cohorts in singapore seasonal influenza risk in hospital healthcare workers is more strongly associated with household than occupational exposures: results from a prospective cohort seroprevalence of antibodies to pandemic (h n ) influenza virus among hospital staff in a medical center in taiwan viral shedding and clinical illness in naturally acquired influenza virus infections we thank p. ching, s.k. pang, a. wong and a. yuen for facilitating our study, and l. chan, q. liao, t. so and j. wong for assistance with the fieldwork. we thank v. fang for technical assistance. key: cord- -dqkjofw authors: small, michael; tse, c.k.; walker, david m. title: super-spreaders and the rate of transmission of the sars virus date: - - journal: physica d doi: . /j.physd. . . sha: doc_id: cord_uid: dqkjofw we describe a stochastic small-world network model of transmission of the sars virus. unlike the standard susceptible-infected-removed models of disease transmission, our model exhibits both geographically localised outbreaks and “super-spreaders”. moreover, the combination of localised and long range links allows for more accurate modelling of partial isolation and various public health policies. from this model, we derive an expression for the probability of a widespread outbreak and a condition to ensure that the epidemic is controlled. moreover, multiple simulations are used to make predictions of the likelihood of various eventual scenarios for fixed initial conditions. the main conclusions of this study are: (i) “super-spreaders” may occur even if the infectiousness of all infected individuals is constant; (ii) consistent with previous reports, extended exposure time beyond – days (i.e. significant nosocomial transmission) was the key factor in the severity of the sars outbreak in hong kong; and, (iii) the spread of sars can be effectively controlled by either limiting long range links (imposing a partial quarantine) or enforcing rapid hospitalisation and isolation of symptomatic individuals. the sars virus first appeared during october in the guangdong province of southern china. it then passed over the border to hong kong and from there spread to europe, africa, asia, australia and the americas [ ] . the outbreak in infected , killing [ ] . in this paper we focus on modelling the transmission of sars within hong kong. beside mainland china, hong kong suffered the greatest casualties [ ] . in addition, the epidemiological data currently available for hong kong is far superior to that of the chinese mainland. two characteristic features were observed during the sars outbreak in hong kong in (see fig. ) [ , ] : so-called super-spread events (sse), in which a single individual initiates a large number of cases; and persistent transmission within the community. two widely cited sses were observed early in the epidemic and have been the subject of much attention: at the amoy gardens housing estate and at the prince of wales hospital. epidemiological studies [ , ] have found that in hong kong: • the fatality rate was approximately % (compared to % globally); • the mean incubation period was . days (range - days) [ ] ; • the duration between onset of symptoms and hospitalisation was - days; and, • the mean number of individuals infected by each case during the initial phase of the epidemic (excluding sses) was . [ ] . standard deterministic sir (susceptible-infected-removed) models of the spread of infectious diseases [ ] make several important assumptions. an alternative approach [ ] , particularly popular for the study of sexually transmitted diseases [ ] [ ] [ ] , is to build an explicit network and model disease transmission along the links. under certain network structures, it is then possible to obtain a closed form study of the underlying transmission pattern [ , ] . in particular, [ ] studied the transmission of an epidemic among a population whose individuals are connected both locally and globally. from this, they were able to obtain an approximately poisson distribution for the contact distribution. in [ ] , hufnagel and co-workers also studied the local and non-local transmission of epidemics. the main features modelled by [ ] are local sir infection (with the usual stochastic differential equations) and long distance complex network links to model global aviation routes. they show that transmission dynamics with similar geographical dispersion to the sars outbreak can develop in the model. in contrast to [ ] , we focus on abstract network models within a particular community. a similar global model of sars transmission could be achieved by introducing an aviation network model on top of the models presented in this paper. recently, both small-world (sw) and scale-free (sf) networks have been observed in many areas of natural and physical science, including social relationships [ , ] . the important feature of both sw and sf networks is that they are highly connected: the average path length between random individuals is relatively short. moreover, for sf networks, the node degree distribution follows a scale-free distribution. hence, in many areas of natural and physical science, this new model structure has unveiled a rich range of behaviours. in this paper, we apply these methods to the modelling of the spread of sars in hong kong; transmission is only allowed to occur along a limited number of direct links between individuals. by doing this, we will avoid making one of the assumptions underlying standard susceptible-infected-removed (sir) models: a homogeneous fully connected population. the sir model assumes that all individuals are susceptible to the disease and all suffer an equal, small, positive probability of contracting the virus. this homogeneous model leads to a continuous and smooth inter-day distribution of infections. irregularities in this are usually attributed to random variation and non-stationarity in the model parameters. in proposing an alternative to the standard sir model, we do not claim that the sir model has failed. certainly, the power of any model lies in its simplicity, and its ability to capture the important features of a system. hence, like the sir model, the complex network model that we describe here is very simple and is described by a very small number of parameters. analysis of the spread of sars with sir models shows good correlation between decreasing infection rate r and the introduction of various governmental control measures: quarantine and public awareness campaigns [ ] . however, these results are based on a very simplistic model, and localised outbreaks (such as the incident at amoy gardens) are not modelled very well. while it is impossible to predict the occurrence of such outbreaks, sw-sf models provide a more realistic physical model of the relationships between individuals in a community and will therefore provide a better picture of the true disease dynamics. note that, since one cannot actually predict when a particular sse will occur, one cannot accurately model the timing of the peak in the time series of fig. . moreover, it is not possible to accurately model the initial sse at the prince of wales hospital, which "kick started" the sars outbreak in hong kong. to include the same initial spread of sars in hong kong, via a rather singular sse, that sse must be included explicitly in the model. in other areas where sw-sf models have been applied, a rich range of behaviours has been observed. unlike standard differential equation based models, sw and/or sf structures model the underlying network of connections between individuals directly. our model is designed to capture explicitly the small-world features of social interaction. our model is not scale-free. to generate a scale-free model for disease epidemics, one needs a power-law distribution of infection links; we consider the theoretical implementation of such a model in a separate paper [ ] . finally, we will also provide one possible answer to the question posed by galvani and may [ ] : "were sars superspreaders anomalies, or are super-spreaders characteristic of most infectious diseases?" [ ] . we show that, even with uniform rates of infection, super-spreaders will occur, to varying degrees, in a small-world or scale-free [ ] network. the implication is that super-spreaders are not (necessarily) a result of variable rate of infection. nonetheless, we argue that the sars outbreak in hong kong was initiated by a single, rather unfortunate, super-spreader event. in the next section, we describe our model and study its behaviour analytically. subsequent sections present some numerical simulations and a summary of our results. in the following subsections, we define our model structure (section . ) and derive some analytical results concerning the likelihood of a widespread outbreak (section . ). our aim is to capture accurately the qualitative features of the sars epidemic with the simplest model (the fewest parameters). we propose four distinct states. individuals can be susceptible (s), prone (p), infected (i), or removed (r). the transmission path is depicted in fig. . infected individuals can cause susceptible individuals, to whom they are linked, to become prone with some probability ( p or p ). by infection we mean the transition from the susceptible state to the prone state. infected individuals can cause their immediate neighbours to become infected with probability p ; long range links cause infection with probability p . prone individuals become infected with probability r and, finally, infected individuals become removed with probability r . just as in the sir model, we do not distinguish fatalities from recoveries: in either case, the individuals are assumed to have acquired immunity. the model states that we describe here bear a close correspondence to the four states of the seir model. the prone state is analogous to the exposed (e) state in the seir model. we choose to use the new term p because the epidemiological state is slightly different. by prone we mean both the infected but not infectious (incubation) period and the pre-symptomatic period. for sars, all infections in hong kong could be traced to contact with a symptomatic individual. hence, for the purposes of modelling transmission, we assume that, during the pre-symptomatic period, there is no chance of transmission. moreover, to calibrate our model with the observed data (which, by definition, are hospital admissions), we further prescribe that the time between the onset of symptoms and hospitalisation is constant (or, equivalently, follows a stationary unimodal distribution). in our model we explicitly model the geographical structure of the population. we include both "local" and "non-local" links. because of common transmission of sars within specific housing estates and districts in hong kong, and the (both real and perceived) risk of transmission in workplaces (primarily hospitals and schools) or other public areas, we model these two types of transmission separately. the geographical arrangement of nodes represents the residence of each individual. so, by "local" transmission, we mean only transmission within a family unit (i.e. residents of a single flat), or between adjacent flats. hence, "non-local" transmission the top panel depicts the transmission state diagram: s to p based on the sw structure and the infection probabilities p , ; p to i with probability r ; and i to r with probability r . the lower panel depicts the distinction between "local" (i.e. short range) and "non-local" (long range) network links. the lower panel shows the arrangement of nodes in a small-world network. the black (infected) node may infect its four immediate neighbours with probability p and three other nodes (hashed) with probability p . refers to transmission between non-family members due to the mixing of individuals in public spaces. in the context of the sars outbreak in hong kong, this would include transmission within hospitals, schools and public spaces. in our model, we expect sse to be represented through a single node with a large number of non-local connections. we fix the population n and assume that there are no other additions to, or deletions from, the population from any other cause for the duration of each simulation. the population of n nodes is arranged in a regular grid, of side length l (l = n ), and each node is connected directly to n immediate neighbours. an infected individual will infect each of its n neighbours (provided that they are still susceptible) with probability p . furthermore, each node has n non-local (i.e. long distance) links (see fig. ). these are links to nodes that are geographically remote from one another; infection occurs along these pathways with probability p . for each node i, the number n (i) is fixed, and so are the links to its n (i) remote neighbours once they are established. the number n (i) is chosen to be proportional to a decaying exponential f x (x) ∝ e − x µ with parameter µ proportional to the expected (average) number of as we will see in what follows, the number of local connections is constant for all nodes. the grid is assumed to be topologically equivalent to the surface of an annulus in three dimensions, that is, nodes ( , ) and (l , l) are neighbours. links to remote nodes, where n (i) it is the inclusion of non-local links with a random number of links that can give rise to the network's sw (and, in other cases not considered here, sf) structure. in this paper, we assign an exponentially decaying probability distribution to any number of links, and (for uni-directional links) this is sufficient to generate the necessary sw properties. an sf network requires a power-law distribution of the number of links (which can consequently lead to more nodes with many more links) and we do not examine that case here. the sf distribution of the induced network of actual infections has been considered elsewhere [ ] . it is worth considering that, for the model that we present here, the links between nodes are uni-directional. that is, infection only spreads in one direction. clearly, the true network of social interaction consists of bi-directional links. but, for the purposes of simulating disease transmission, unidirectional links appear to be a sufficient approximation. the consequence of this is that it becomes easier to generate the small-world (and elsewhere the scale-free) network. finally, for each simulation we seed the model with one randomly chosen initial infection. we expect that computational simulations of this network will show that infection spreads locally, just as sars spread within particular geographical regions of hong kong. moreover, the system can also exhibit non-local infection, as a single individual may infect individuals in distant communities. occasionally, individuals will infect a large number of others, exactly as was observed at the start of the sars epidemic in hong kong (an sse). however, unlike the start of the sars epidemic in hong kong, because we seed our population with a single infectious individual, we do not expect to see the initial sse triggered by that individual (except by chance). therefore, the initial growth of transmission in our model is exponential rather than an sse. the only way to overcome this is to include explicitly the "seed" sse in the model, regardless of network topology. the epidemic will eventually be contained if the rate of infection is lower than the rate of removal. intuitively, provided that (n p + µp ) r , one would expect the disease to become endemic; conversely, if (n p +µp ) r , the disease will be contained. in what follows, we study this condition more precisely. moreover, with this model we can analytically compute the probability of an outbreak being self-terminating. for a single infectious node, the probability of no further infections on a given day is given by hence the probability of no further infections from this node can be closely approximated by the infinite geometric series using the average p no computed in eq. ( ): provided that |p no ( − r )| < . upon substitution of eq. ( ) into ( ), we find that eq. ( ) is the probability of no infections from a given individual, and is therefore a weak lower bound on the probability of no general outbreak. now, let us denote the probability of no further infections occurring, given that there are k infectious nodes by = p (k) none = prob(no further infection | k infectious nodes) where, for notational convenience, we will drop the subscript on p none . treating infections as discrete events (i.e. they occur one at a time), we have that ( − p k ) is the probability of at least one further infection from k infectious nodes. the probability that the epidemic will terminate is given by where p = p none is given by eq. ( ). by expanding eq. ( ) and comparing to the pentagonal number theorem, we find that eq. ( ) can be rewritten as an infinite sum ( − p n ) = p + p − p − p this result was originally proved by euler in . where the sequence of indices , , , , , , , , , . . . is the generalised pentagonal numbers (described as sequence a in [ ] ). eq. ( ) may also be re-written in terms of the dedekind eta function, but for the purposes of this discussion it is unnecessary to do so. nonetheless, for ≤ p < this sequence converges fairly rapidly as the order of the exponent increases. the exact probability of a general outbreak can alternatively be obtained by using a branching process method. following [ ] , we define the probability generating function for the number of secondary cases produced by a single infectious case in a day. then the probability generating function for the overall number of secondary infections from a single primary case is one can then obtain the probability of no general outbreak (i.e. the probability of the disease not becoming endemic) as the smallest solution x ∈ [ , ] of g(x) = x. unfortunately, eq. ( ) cannot be readily used for further analysis. similarly, although eq. ( ) can be computed easily, it is not in a form that is immediately amenable for further analysis. however, since p safe ≥ p none , it is clear that will make p safe ≈ . hence, either µ or p ≈ will lead to widespread infection (as expected). differentiating ( ) with respect to ( − p ) n , we can easily verify that p safe is a monotonic function of both p and n . one can therefore observe that p safe ≈ if p ≈ or n . the most severe limitation on eq. ( ), and also eqs. ( ) and ( ) , is that we assume that no infected nodes have common neighbours, and that all of the neighbours are susceptible. in reality, the number of potential infections is limited by the fact that some of the potential neighbours are already infected. it is therefore important to estimate the number of neighbours of an infected node that have not been infected. this is equivalent to estimating the ratio of local and non-local infections in an epidemic. one can consider the network of infected individuals as consisting of a number of "clumps": one clump because of the assumption that infections occur individually and sequentially, the branching process in eq. ( ) is only an approximation to the solution of eq. ( ). we can achieve this as follows. suppose that there are no non-local infections (i.e. p = ) and that infections grow in a single (roughly spherical) "clump". then, if the clump consists of i (t) individuals, then the radius of this for each non-local infection (i.e. each clump is seeded by a nonlocal transmission; all other transmissions within that clump are local). provided p > , this implies that, as the clump gets bigger, the probability of any given infection being a long range infection will increase. conversely, as the number of clumps increases, the probability of local infection (relative to nonlocal infection) will increase. let us now estimate the expected number of connections from an infected node. let n s denote the expected number of susceptible nodes linked to a random node. if this node is the result of a non-local infection, then we suppose that n s = n + µ; however, if this is the result of a short range infection, then this number should be lower (certainly no more than µ + n − ). now, where k is the proportion of local links that support possible infection and < k ≤ n − n . hence, from the preceding geometric argument, if infection grows in a single clump, then k ≈ . moreover, k < only if nodes remain infected when they are on the interior of such "clump" (i.e. when r is very low). we would therefore expect that ≤ k ≤ n − n . note that k is not a model parameter, but rather it is a term in the model that will both depend on the various model parameters and vary with time. finally, we now consider the rate of transmission. let p(t), i (t) and r(t) be the number of prone, infected and removed individuals at time t (in days). the probabilities r and r can therefore be considered as the rates at which prone nodes become infectious and infectious nodes become removed (respectively). similarly, (n p k+µp )s(t)i (t) is the expected number of new infections. suppose that s(t) r(t) + i (t) + clump will be i (t) π and the number of susceptible individuals is √ i (t)π . now, further suppose that all nodes in the clump are infectious (i.e. r = ), then the mean number of links per infected individual is π i (t) . even with r > , as the clump grows, there are, on average, fewer potential infection paths. moreover, one can estimate the number of clumps k . observe that k ≈ µp n p +µp × (number of infections). more precisely, n p (n k p + µp ) + µp (n kp + µp ) × i where i is the total number of infections. where n k = (n p k + µp ) is the expected number of links for each infectious node. we are now modelling the inter-day process assuming discrete day-to-day dynamics. the reason for this approximation is that the available time series data (which will be the basis of our comparison) is similarly course-grained. assuming that the population is seeded with a single infectious individual, the solution of eq. ( ) is given by where is the matrix of eigenvectors and is formed from the corresponding eigenvalues, given by it then follows that the system has a marginally stable focus (i.e. the epidemic will terminate) if |λ , | < , i.e. n k < r ( ) n k r < ( − r )( − r ). the second condition ( ) is only violated if n k > , which would also violate condition ( ) . therefore, the epidemic is controllable provided that n k = n p k + µp < r . the right hand side of this inequality is the rate of infection and the left hand side is the rate of removal, as expected. in fact, this result is exactly analogous to the equivalent result for the continuous sir model [ ] . moreover, computationally, we can see that, as r or n k increases, then the rate of growth of the epidemic also increases. conversely, as r increases, the rate of growth decreases. this is as one would expect, as increasing r will decrease the number of infectious individuals while increasing either r or n k increases this quantity. in the following subsections, we confirm the preceding relationships and numerically explore the behaviour of our models under a variety of conditions. as stated, our model has seven explicit parameters: l, n , µ, p , p , r , and r . for the population of hong kong, we set l = (n = l = , , ). we arbitrarily choose n = and set e(n ) = µ = [ ] . one further parameter is the time interval between successive steps in the discrete time simulations from our model. we choose the natural scale of one day. however, it is not obvious that this is the best choice. given that the data is discretised to this interval, it is perhaps the best choice in this situation. nonetheless, to confirm that this choice is appropriate, we have repeated our analysis with both longer and shorter time steps. the results are equivalent. the average incubation period between infection and an individual becoming symptomatic is . days [ ] . the number of days in the prone state can therefore be modelled as the result of a series of independent bernoulli trials with a mean r and so it follows a geometric distribution f x (x) = ( − p) x− p. for a general disease model, it would possibly be more appropriate to have a separate state for the pre-symptomatic but infectious period. although contact tracing of all sars patients in hong kong has demonstrated that this is not a significant period for sars, we have repeated the simulations with this state. if the hiatus in this state is relatively short, the results are not altered significantly. in a similar spirit, the time before hospitalisation is - days, and we model this as a series of independent bernoulli trials. in an effort to establish the degree to which hospital transmission in our model matches what was observed, we first assume that hospitalisation is equivalent to isolation of infectious individuals. that is, we suppose that infectious individuals are only infectious for - days. the current weight of evidence suggests that hospital transmission was a crucial factor for the sars outbreak in hong kong during . we will show that this is also the case for our model. hence, we suppose for now that the average amount of time prior to isolation is days (we will consider larger values later). in our model, the number of days prior to hospitalisation is also made to follow a geometric distribution with mean r . hence, the only free parameters are µ, p and p . without active control, we also know that the average number of new infections per case (excluding sses) is . [ ] . in this state, each infectious individual will infect, on average, n p + e(n ) = µ and we suppose that the time before hospitalisation is d days, we have we set d = and therefore p ≈ n ( . − µp ) = . − µ n p . in subsequent simulations, we also consider d = , , and also a larger number of new infections than . . we do it this way simply because it is convenient to do so. for simulation purposes, this sequence of bernoulli trials is both easy to implement and (more importantly) requires very modest computational storage resources. in each case, the results are equivalent to those presented here. however, we maintain the values described above in the following discussion. any deviation of results between these and other values will be highlighted in the text. our initial model parameters are therefore [ ] : note that, because we have the possibility of p to i transition after zero days, r = . rather than . . this does not have a significant effect on our results; it is merely a computational convenience. now, from eq. ( ) we can deduce that the rate of growth of infection is approximately which, for r = . , yields either a growth rate significantly less than exhibited in the data or rates of infection significantly greater. even for reasonable variation of d and the average number of secondary infections, we obtain similar results. hence, we conclude that the assumption of no nosocomial transmission is inconsistent with the observed data. increasing the average infectious time to days gives a substantially higher rate of infection: consistent with the observed data. subject to eq. ( ), we explore which parameter values give a significant probability of the epidemic becoming endemic. from eq. ( ), we have that p safe = if n k < r . consistent with the discussion of the preceding section, we start with the assumption that k = n − n and set n = and µ = . fig. is a plot of the probability of complete infection for various parameter values estimated from the data and eq. ( ). we see that there is close agreement between the theoretical and experimental results. moreover, we note that a smaller value of k is appropriate for scenarios with a relatively high proportion of local spreading (i.e. p larger and p ≈ ). this is consistent with the case of spreading within a single clump, and we approach the situation of k = . however, in these simulations the best choice is k > in all cases. only for extremely small values of r and p would we expect smaller values of k. typically, k = n − n = seems to be a good choice. furthermore, in fig. it is evident that the greatest probability of an epidemic becoming endemic is when there is both local and non-local infection. in the model that we have constructed here, local infection spreads approximately geometrically, while non-local infection spreads exponentially. yet, it is some combination of both that provided the greatest possibility of an outbreak spreading without control. clearly, exponential growth will lead (all else being equal) to more rapid growth of an epidemic than geometric growth. but, by combining some geometric growth, the epidemic becomes even more dangerous. it seems that the additional local transmissions allow each nonlocal transmission the possibility of seeding a new infection cluster (rather than just a single point), and each new cluster is more difficult to eradicate than a single point infection. fig. depicts level curves for the probability of fixed levels of infection. that is, we compute the parameter values p , ∈ [ , ] and r ∈ [ . , . ] required to achieve specific values of p safe . we see that only for p , . is the outbreak likely to be controlled. moreover, the variation with r is not critical i.e. the range of behaviour for specific p , is not great. finally, in fig. we plot the probability of the epidemic being controlled for various values of µ with p , ∈ [ , ], r = . and r = . . consistent with fig. , results for different values of r , did not change significantly. moreover, from fig. we see that only for µ > does the infection probability p have a significant effect. that is, to limit long range infection, one should aim to reduce the average number of long range links below . we find that, for all values of p , and µ > , there was remarkably little variation in the value of p safe . however, the rate of infection (eq. ( )) did change significantly. subject to the choice of parameters in the previous sections, we now simulate the expected dynamics and compare this to the theoretical bounds of section . . according to theory, restricting the infectious period to five or fewer days does not yield a growth rate large enough to be consistent with the observed data. we test that assertion numerically and find that the observed data (over individuals infected after days) is inconsistent with the simulation for r = . . however, by lowering r to . (and therefore increasing the mean infectious period to six days, we achieve results more consistent with the observed data. we see that only with r ≥ . do we obtain results for which the true data is not statistically atypical. moreover, this result is robust to moderate changes of the other relevant parameters, as illustrated in fig. . we conclude that the obtained results for which the true data is not atypical; we require r ≥ . (i.e. a mean exposure time of six or more days). moreover, we see from fig. that widespread infection is associated with a large number of clusters. the results of the next section corroborate this. to examine the role of clustering more closely, fig. is a snapshot of a single simulation for parameter values r = . and p = . . this simulation shows sse resulting from clustering and highly connected nodes. moreover, the gradual spread of the disease within a single cluster is evident; one can see that the number of clusters is far less than the number of infections. time series of the infection total appear qualitatively similar to the hong kong sars data. specifically, burstiness typical of sses is evident. however, the quantitative behaviour of this model is remarkably different to the dynamics observed in the sars outbreak. the daily number of reported infections in fig. far exceeds the total number of active infected and prone individuals in fig. . finally, we provide simulations of the hong kong epidemic and from multiple simulations estimate the likelihood of various outcomes based on the model. we initiate the model with a single infected individual and a relatively low removal rate r . fig. depicts our results. we can see from fig. that many of the features of the true data are reproduced well in the simulations. however, two important aspects of the simulations are not sufficiently similar to the data. firstly, the initial spreading of the disease is exponential, rather than the single sse observed in the real data. secondly, the magnitude of the sses in the simulations is somewhat smaller than the largest sses in the data. this second aspect can be overcome by simply altering the distribution of non-local links. in [ ] we describe how a power-law distribution of links can lead to many more extreme events. conversely, the initial sse in the data cannot be modelled well by our simulations, except by chance. therefore, to achieve similar initial events, we would expect that we would have to execute many simulations (and choose only those that suit our purpose), or simply build the sse into the model. neither of these approaches are desirable. we prefer to focus on the possibility of sses occurring randomly, without explicitly adding them in the model. hence, we do see sses, but not necessarily immediately after the start of the simulation (as we suppose occurred in the true data). we now wish to demonstrated how the sw model described here improves on stochastic sir-type models [ ] . one very simple way to achieve this is to compare the distribution of statistic values measured from simulations of either type of model to the true data. in fig. we do this, and we find that the small-world model exhibits statistical properties much closer to the observed data. in fig. we compare the results for the sirtype model (with stochastic inputs) to the sw model described in this paper. by generating multiple simulations of both models and estimating simple statistical measures from both sets of simulations, we see that the model dynamics of the sw model are much closer to the true data. assuming that this model and parameters are accurate, or at least appropriate, we compute the likely behaviour for various epidemics. we generated realisations of the model depicted in fig. and computed the total number of casualties. fig. is a plot of the probability distribution of the number of fatalities for these simulations, and fig. is the probability distribution for the daily number of infections. we found that the probability of infecting fewer than people was approximately . , while the probability of infecting more than was . . one can see that, with respect to these gross statistics, the true situation for hong kong ( casualties) is quite typical. it is interesting to note, however, that there is a large variation in the number of casualties. in all cases, the parameter values of fig. provided effective control of sars transmission after approximately days. from these simulations, we therefore conclude that, with effective control measures in place, the likelihood of a significant outbreak is low. from simulations, exhibited a larger number of casualties. we summarise the main results of the preceding sections as follows. • the probability of the disease spread being controlled, p safe , is approximately • the epidemic is under control if n k = n kp + µp < r (section . ). • for the endemic case, the rate of growth of infection is • this model exhibits behaviour consistent with both sses and persistent localised transmission (section . ). more extreme sses can be observed simply by fattening the tail of the distribution of links. by assigning a power-law distribution to the number of nonlocal links that a node has, one can readily obtain sse involving many hundreds of secondary infections from a single source. • an sse does not imply highly infectious individuals, only highly connected ones (section . ). • theoretical results and model simulations are unlike the true data, unless exposure time is significantly greater than an average of three days (sections . and . ). if the exposure time is three days or less, the rate of growth of the epidemic is significantly lower than that observed in the true data. • nosocomial transmission was therefore a key factor in the acuteness of the sars epidemic in hong kong in . effective control of hospital transmissions would have prevented a serious outbreak (section . ). with respect to nosocomial transmission, our model therefore confirms what has been observed independently, and suggested by many authors. • simulations of our model, with minimal parameter variation, produced dynamics indistinguishable from the true data. these same parameter values exhibit a wide variety of behaviours (section . ). hence, any effort to actually obtain maximum likelihood parameter estimates from the observed data is futile. despite this, our calculations show that the true data is certainly typical of our models. moreover, our models exhibit a marked long-tailedness both in infection times and epidemic lifetimes. • the likelihood of infecting fewer than people was approximately . , and the likelihood of infecting more than was . (section . ). apart from deriving analytic expression for the spreading and control of an epidemic, the main results of this study, when applied to the sars epidemic in hong kong in , is that our data is consistent with the observation that the epidemic that occurred was largely preventable. the primary factor for the severity of the outbreak was poor infection control in the hospital setting and the delayed introduction of quarantine and community isolation practices. this is consistent with various discussions presented elsewhere. however, we note that nosocomial transmission was considered only by supposing (admittedly erroneously) that the time between becoming symptomatic (and infectious) and hospitalisation is constant. nosocomial transmission is simulated by changing the expected duration between becoming symptomatic (i) and becoming removed (r). although this is perhaps unconventional from an epidemiological viewpoint, it is probably the best that we can do, as the only data that we have to work from is the date of hospital admission. this conclusion is in contrast with work done by pastor-satorras and colleagues [ , ] with scale-free sis type [ ] disease models. in that case, they found that the disease would almost always persist and that random immunisation was ineffective [ ] . the model presented here emphasised the small-world transmission dynamics created by providing a small number of highly connected nodes. we model the inter-connection between nodes with one-directional links (rather than the bi-directional links we would expect for social contacts) because this makes the network much easier to construct, without sacrificing any realism. this model could easily be extended to exhibit scale-free characteristics, by simply altering the distribution of non-local links (to follow a power-law distribution). doing so would produce simulations with a larger number of highly connected individuals, and therefore we could simulate the largest sses in the data. the results presented in this paper show small (less than individuals) sses; extension to the power-law distribution would provide sses with a larger number of secondary infections. we should note that it is very difficult to reliably and accurately fit even a moderate number of parameters to a stochastic model from such limited data. especially when the model, for the same parameter values, can exhibit a wide variety of behaviour. to overcome this, we (a) make our model so simple that the number of parameters is very few (certainly comparable in number to ordinary sir), and (b) only "fit" the model with typical parameter values and test that, for these parameter values, the observed data is typical. certainly, we cannot exclude the (quite likely) probability that other parameter values also produce behaviour of which the observed data is typical. therefore, in this paper we only draw conclusions based on our observations of parameters that produce behaviours that are either typical or (more importantly) atypical of the observed data. although we have observed that our model exhibits more realistic dynamics than sir models, it is only a model. and, like the sir model, our model is a compromise between complexity and realism. we intend to address this problem in the future by applying monte carlo markov chain models [ ] to this sparse data [ ] . even our choice of a discrete time model is open to debate. the choice, with a time interval chosen as one day, was motivated by the data and what was more intuitive to us. we have conducted calculations with both longer and shorter interinterval time scales and find that the results are invariant under a suitable change in time scale (i.e. we get equivalent results by using a shorter time step). moreover, recent epidemiological case studies have found that, overall, in hong kong % of individuals sharing a flat with a sars patient contracted sars [ ] . given an average infectious period of four days (prior to hospitalisation), this implies that the daily probability of transmission is . . this is approximately consistent with the values of p used in this study, and therefore provides further support of our results. conversely, analysis of the sse at the prince of wales hospital found that, for a group of medical students, the probability of direct contact with the index patient leading to sars infection was [ ] . as this study dealt with a single meeting, this implies a daily infection probability of approximately . : significantly higher than p in our simulations. hence, although we have concluded that sses may occur without individuals necessarily being highly infectious, epidemiological evidence suggests that, in some cases, this may still be the case. finally, we note that, although the methods presented here are applied only to the sars outbreak in hong kong in , these methods are not limited to this situation. apart from repeating, or modifying, this analysis for different infectious diseases (such as hiv aids), we imagine that these techniques could be useful in the theoretical study of quarantine and isolation practices, as well as disease transmission among isolated communities. quarantine can be effectively modelled as a limitation of long range transmission. one can easily model change in quarantine by varying the parameter µ (or alternatively, but not equivalently, p ). this should provide a new, simpler approach to the study of quarantine to supplement compartmental models such as those described in [ ] . world health organisation, consensus document on the epidemiology of sars report of the severe acute respiratory syndrome expert committee transmission dynamics of the etiological agent of sars in hong kong: impact of public health interventions cluster of sars among medical students exposed to single patient epidemiological determinants of spread of causal agent of severe acute respiratory syndrome in hong kong mathematical biology modeling infection transmission more realistic models of sexually transmitted disease transmission dynamics: sexual partnership networks, pair models and moment closure a versatile ode approximation to a network model for the spread of sexually transmitted diseases likelihood-based inference for stochastic models of sexual network formation, theor poisson approximation for epidemics with two levels of mixing forecast and control of epidemics in a globalized world six degrees: the science of a connected age collective dynamics of 'small-world' networks small world and scale free model for transmission of sars dimensions of superspreading on-line encyclopedia of integer sequences, online mathematical epidemiology of infectious diseases epidemic spreading in scale-free networks epidemic dynamics and endemic states in complex networks bayesian inference for partially observed stochastic epidemics stochastic modelling of ecological processes using hybrid gibbs samplers probable secondary infections in households of sars patients in hong kong simulating the effect of quarantine on the spread of the - flu in central canada this work is supported by funding from the health, welfare and food bureau of the government of the hong kong special administrative region under the research fund for control of infectious diseases (rfcid). dw thanks the scottish executive environment and rural affairs department (seerad) for support. key: cord- -yq dtf n authors: samaranayake, lakshman p.; peiris, malik title: severe acute respiratory syndrome and dentistry a retrospective view date: - - journal: the journal of the american dental association doi: . /jada.archive. . sha: doc_id: cord_uid: yq dtf n abstract background severe acute respiratory syndrome, or sars, which has created panic in asia and in some parts of north america, is the first epidemic of the new century. although it has been well-contained, sporadic cases continue to emerge. objectives the authors trace the emergence of the sars outbreak from southern china and its spread worldwide, discuss the viral etiology of the infection and its clinical features, and review the infection control guidelines issued during the outbreak by the health authorities in hong kong, the centers for disease control and prevention, the world health organization and the american dental association. they also review the prospects for a new outbreak and preventive measures. overview the disease, which is caused by a novel coronavirus termed the “sars coronavirus,” or sars-cov, essentially spreads through droplet infection and affects people of any age. it has a mortality rate ranging from to percent. a major hallmark of this disease has been the rate at which it has affected health care workers through nosocomial transmission; in some countries, up to one-fourth to one-third of those infected were in this category. however, no dental health care worker has been affected by sars in a nosocomial or dental setting. conclusions and clinical implications researchers believe that a combination of factors, including the universal infection control measures that the dental community has implemented and/or the low degree of viral shedding in the prodromal phase of sars, may have obviated the spread of the disease in dental settings. the dental community should reflect on this outbreak to reinforce the currently applied infection control measures. m icrobial threats continue to emerge, reemerge and persist. some organisms are newly recognized pathogens that have existed for centuries (for example, helicobacter pylori, which causes gastric ulcers). others are old organisms that have learned new tricks (for example, multidrug-resistant tubercle bacilli). a third category consists of totally new organisms. this last group of alarming new infectious agents that are virulent and deadly have emerged in rapid succession during the last few years. some of these, such as the ebola virus infection, are still smoldering in some remote corners of the world, while others, such as the h n (and h n ) influenza a bird flu virus and the west nile virus infections, are emerging in different parts of the world. severe acute respiratory syndrome, or sars, is the latest addition to this deadly assortment of new diseases. in the face of these infectious threats, in particular the pandemic of hiv infection, the dental community has reacted swiftly by adopting standard precautions. dentists follow a uniform infection control protocol to treat all patients, irrespective of their medical histories. however, in the face of a new infection that is considered highly contagious, it is prudent to review infection control procedures. the objective of this article, therefore, is to describe the epidemiology, clinical features, etiology and prevention of sars, as well as to evaluate the current infection control protocols used in dentistry in view of the facts related to the spread of this infection. we also explore the prospects for recrudescence of the disease, its treatment modalities and the promise of a sars vaccine. we do not know with certainty how, where and when the disease now known as sars manifested in humans, although theories abound. in february , the world health organization, or who, coined the term "severe acute respiratory syndrome" for the flulike condition that developed into pneumonia. nonetheless, researchers and clinicians generally believe that the first few cases may have originated in china. these sporadic cases were described sometime in the fall of in the guangdong province in southern china. for decades, the guangdong province had a large concentration of people, pigs and fowl living in close proximity because of mixed farming traditions that date back for centuries. this region also has the dubious distinction of being the deadly source of the asian flu, caused by the h n virus, which killed about million people worldwide in and . in , the avian flu (caused by the h n virus), which killed six people, also originated in the guangdong province. the recent outbreak. the sars outbreak has been identified in more than countries in five continents, affecting more than , people, predominantly in asia (especially china), with mini-outbreaks in north america and a few cases in europe. the disease has led to more than deaths worldwide. clusters of cases are particularly common among close associates of patients and the health care workers who treated them and their household contacts. because of the alarming global spread of the disease, who issued a global alert in march and instituted worldwide surveillance. patient characteristics. most patients identified up to now were previously healthy adults aged through years. a few cases of sars have been reported among children (≤ years of age), in whom the clinical course now is thought to be less aggressive. we provide a summary of the major clinical characteristics of patients with sars, although the information should be considered preliminary because of the broad and nonspecific case definition. clinical features. the incubation period for sars is widely considered to be two to seven days, but occasionally may last up to days. symptomatically, the illness appears to have two phases: an early, prodromal febrile phase and a secondary lower-respiratory phase. in pathological terms, however, it is a triphasic disease with a primary viral replicative phase, a secondary immune hyperactive phase and a pulmonary destructive phase. the disease generally begins with a prodrome of typically high fever (> c) that may be accompanied by chills and rigors. headache, malaise and myalgia also are common. at the onset of the illness, some patients have mild respiratory symptoms. in a few cases, the febrile prodrome may be accompanied by diarrhea, although rash and neurologic or gastrointestinal findings are absent. after three to seven days, the secondary lower-respiratory phase begins with a dry, nonproductive cough or dyspnea that may be accompanied by, or progress to, hypoxemia. in up to one-fifth of the cases, the respiratory illness is severe enough to require intubation and mechanical ventilation. the fatality rate among patients with illness that meets the current who definition for probable and suspected cases of sars ranges from to percent, depending on the age group and possibly other, yet unconfirmed, factors. furthermore, the mortality rate is higher among those with underlying illnesses and among the very elderly. typically, chest radiographs appear normal during the febrile prodrome and, in some patients, throughout the course of the illness. however, in the majority of patients, the respiratory phase is characterized by early focal infiltrates that progress to more generalized, patchy, interstitial infiltrates, sometimes leading to consolidation in the very late stages. in general, in the early phase of the disease, patients may have either a normal or decreased white blood cell count, with a reduction in the absolute lymphocyte count. at the peak of the jada, vol. , september c l i n i c a l p r a c t i c e symptomatically, the illness appears to have two phases: an early, prodromal febrile phase and a secondary lowerrespiratory phase. c l i n i c a l p r a c t i c e nomenon not common among other human coronaviruses. medical workers in hong kong, toronto and germany noted this effect when they inoculated lung tissue of patients into cultured monkey kidney cells. [ ] [ ] [ ] this phenomenon leads to a classic cytopathic effect in which the confluent cell layers in laboratory cell cultures are broken down, causing patchy denudation and detachment of cells. [ ] [ ] [ ] immunofluorescence testing of the infected cells indicated that they were indeed infected with a new form of the coronavirus, which has been termed "sars coronavirus," or sars-cov. furthermore, antibodies to the sars-cov were found almost exclusively in patients with sars during their convalescence, but not in human serum samples from healthy patients or in samples banked before the outbreak, suggesting that the infection is new to humans. until now, human coronaviruses have caused the relatively innocuous common cold. however, coronaviruses that infect other mammals and birds are more virulent. these include avian infectious bronchitis (a major problem in the poultry industry), transmissible gastroenteritis of pigs and feline infectious peritonitis. although there was initial speculation that close contact between poultry and humans in the chinese province of guangdong (where sars is thought to have originated) may have resulted in the virus' crossing the species barrier from poultry to humans, evidence now indicates that the himalayan palm civet cats that are consumed as a delicacy and sold widely in animal markets in china are the source of the infection. however, the sars-cov is not a recombinant of known coronaviruses. analyses of the genetic signatures of the viral strains from different geographic regions indicate that immunological pressure might modulate the evolution of the virus in human population cohorts. , other candidate organisms such as paramyxovirus and chlamydia have been implicated in the disease process, but the consensus is that they play a very small role, if any, in the pathogenesis of sars. general properties of coronaviridae. coronaviridae are a family of rna viruses that have been associated etiologically with respiratory ill-lower respiratory phase, up to one-half of patients exhibit leukopenia and thrombocytopenia or platelet counts at the low end of the normal range ( , to , per microliter). renal function appears to remain normal in the vast majority of patients. the box shows the second interim case definition for sars, provided by the centers for disease control and prevention, or cdc. it is based on clinical, epidemiologic and laboratory criteria. however, in areas such as hong kong, where there has been significant disease activity, the cdc criteria have been amended to include patients who do not respond to appropriate antibiotic therapy for atypical pneumonia caused by conventional agents (such as mycoplasma pneumoniae and chlamydia pneumoniae) and/or are in direct contact with another patient with sars. treatment and prevention. a number of treatment regimens have been explored for sars. these include a variety of antibiotics to presumptively treat known bacterial agents of atypical pneumonia, as well as antiviral agents such as oseltamivir and ribavirin. steroids also have been administered in combination with these antimicrobial agents. however, the most beneficial regimen remains to be determined. until reliable diagnostic tests, an effective vaccine and antiviral drugs are available, control of the epidemic depends on early identification of suspected and probable cases, quarantine of patients (and their close contacts) and effective infection control measures, particularly after patients are admitted to a health care facility. etiology. researchers have confirmed that a new strain of virus belonging to the family coronaviridae is the prime agent of this disease. [ ] [ ] [ ] [ ] although other viruses belonging to paramyxoviruses such as metapneumovirus have been implicated, these appear to play only a secondary role, if any, in the disease process. the coronaviruses-so named for the crown of spikes they carry on their surface -attracted the interest of researchers when they noted that the virus rapidly infected cells in culture, a phe- is the prime agent of severe acute respiratory syndrome. copyright © american dental association. all rights reserved. one or more of the following exposures in the days before the onset of symptoms: dtravel to a foreign or domestic location with documented or suspected recent transmission of sars-cov; dclose contact † with a person with mild-to-moderate or severe respiratory illness and history of travel in the days before onset of symptoms to a foreign or domestic location with documented or suspected recent transmission of sars-cov likely exposure to sars-cov one or more of the following exposures in the days before onset of symptoms: dclose contact with a person with confirmed sars-cov disease; dclose contact with a person with mild-to-moderate or severe respiratory illness for whom a chain of transmission can be linked to a confirmed case of sars-cov disease in the days before onset of symptoms laboratory criteria tests to detect sars-cov are being refined and their performance characteristics assessed; therefore, criteria for laboratory diagnosis of sars-cov are changing. the following are general criteria for laboratory confirmation of sars-cov: ddetection of serum antibody to sars-cov by a test validated by the centers for disease control and prevention, or cdc (for example, enzyme immunoassay); or disolation in cell culture of sars-cov from a clinical specimen; or ddetection of sars-cov rna by a reverse transcriptase polymerase chain reaction test validated by cdc and with subsequent confirmation in a reference laboratory (for example, cdc) dprobable case: meets the clinical criteria for severe respiratory illness of unknown etiology and epidemiologic criteria for exposure; laboratory criteria confirmed or undetermined dsuspect case: meets the clinical criteria for moderate respiratory illness of unknown etiology and epidemiologic criteria for exposure; laboratory criteria confirmed or undetermined a case may be excluded as a suspect or probable sars case if: dan alternative diagnosis can fully explain the illness; dthe case has a convalescent-phase serum sample (that is, obtained > days after symptom onset), which is negative for antibodies to sars-cov; dthe case was reported on the basis of contact with an index case that was subsequently excluded as a case of sars, provided other possible epidemiologic exposure criteria are not present * adapted from the centers for disease control and prevention. † close contact is defined as having cared for or lived with a person who has sars, or having a high likelihood of being in direct contact with respiratory secretions and/or body fluids of a person with sars (during encounters with the patient or through contact with materials contaminated by the patient), either during the period in which the individual was clinically ill or within days of resolution of symptoms. examples of close contact include kissing or embracing, sharing eating or drinking utensils, close conversation (less than feet apart), physical examination, and any other direct physical contact between people. close contact does not include activities such as walking by an individual or sitting across a waiting room or office for a brief time. ness in humans and with other diseases in domestic animals. interestingly, they also are associated to some extent with human diarrheal diseases. structurally, they are to nanometers in diameter, positive-stranded and about kilobases in length. their genome is the largest of all rna viruses, and highfrequency recombination between related coronaviruses leads to the generation of much genetic diversity. the virus has three major proteins. the nucleocapsid protein is enclosed within the viral envelope with the rna in a helical nucleocapsid. the other two proteins are the membrane glycoproteins and the spike glycoprotein. the spike glycoprotein is responsible for the characteristic fringe of crownlike projections. antibodies that elicit spike glycoprotein are thought to confer protection against infection. because the human strains are relatively difficult to culture compared with animal strains, the extent of strain variation in human coronaviruses is unclear. there are three serologically and genetically distinct groups of coronaviruses associated with animal and human disease. in general, they are species-specific, although there are a number of examples of viruses crossing species barriers and establishing themselves in new hosts. , once the host is infected, the virus may produce localized disease that often is restricted to the respiratory epithelium or the gastrointestinal tract, or they may produce disseminated infection causing systemic disease. coronavirus was confirmed as the etiologic agent in sars via serologic techniques demonstrating a rise in antibody titer, its growth in tissue culture, a determination of reverse transcriptase-polymerase chain reaction, or rt-pcr, specific for this virus using molecular genetic techniques, and animal studies. animal studies have helped to satisfy koch's postulates, which are necessary to prove disease causation. these postulates stipulate that to be the causal agent, a pathogen must meet four conditions: it must be found in all cases of the disease, it must be isolated from the host and grown in pure culture, it must reproduce the original disease when introduced into a susceptible host, and it must be found in the experimental host so infected. however, further studies that include control groups are required to determine the role of other agents, if any, in causality or as cofactors for severe disease. virus infectivity and survival. the rapid spread of sars worldwide within a few months points to the contagious nature of the disease. the infectivity during the incubation period is still unclear, and it appears that the risk of transmission during the prodrome is low. in contrast, in coronaviruses that cause the common cold, the viral shedding period usually precedes the onset of clinical symptoms by one to two days, although the peak viral excretion occurs during the symptomatic phase. , , the infectivity of sars during convalescence appears to be low and remains to be determined. some data on the survival and infectivity of the sars coronavirus indicate that, unlike other coronaviruses, it is a rather robust organism that is stable in feces (and urine) at room temperature for at least one to two days. it is more stable (up to four days) in stool from patients with diarrhea (which has a higher ph than does normal stool). however, the virus loses infectivity five minutes after being exposed to commonly used disinfectants and fixatives, including percent formaldehyde, percent hypochlorite, percent ethanol and percent phenol. heat at c kills the sars coronavirus at around , units per minutes (considered to be a quick reduction). spread of the disease. the available epidemiologic data suggest strongly that the main routes of virus spread are droplets, direct contact and fomite (indirect contact) transmission, although airborne transmission has not been ruled out completely. researchers believe that the cause of the large outbreaks among health care workers was the transmission of droplets through aerosol-generating medical procedures, such as the use of nebulizers. , no firm data exist regarding the infectivity of contaminated saliva (as opposed to sputum from the respiratory tract) through the droplet route. in some patients, the infection manifests itself as a mild form of diarrhea, and coronavirus particles have been recovered from fecal matter. hence, it is possible that fecal contamination could lead to the spread of the disease, although more data are needed to confirm this route of transmission. it is interesting that some animal coronaviruses are spread through the fecal-oral route. laboratory diagnosis. the mainstay of the sars diagnosis is its characteristic clinical features mentioned above. however, a number of laboratory tests-including serologic tests, cell culture and molecular diagnostics-can be used to confirm the clinically suspicious or probable cases. , these tests include the following. enzyme-linked immunosorbent assay, or elisa, test. from about days after the onset of clinical signs, elisa tests can be used to detect immunoglobulin, or ig, m and iga antibodies in the serum samples of patients with sars. early antibodies are detected in some patients within two weeks. immunofluorescence assay. sars virusinfected vero cells can be used to detect igm antibodies in serum samples of patients after about day of the onset of the disease. this test is reliable, yet demanding, because the live virus must be grown in cell culture; in addition, subsequent immunofluorescence needs to be demonstrated. cell culture. laboratory workers can detect virus in specimens (for example, respiratory secretions, blood) from patients with sars by infecting cultured vero-e or fetal rhesus kidney , or frhk- , cells. molecular tests. laboratory workers can use pcr assays that detect genetic material of coronavirus in patient specimens (such as respiratory secretions, blood or stool samples). primers that are required for this test now are available widely through various web sites (for example, the cdc, the university of hong kong and the governmental viral unit of hong kong). interpretation of test results. clinicians must exercise caution when interpreting laboratory test results, because the key to diagnosis is clinical evaluation and possible exposure to an infected person. a positive laboratory test result indicates that the patient is, or has been, infected with the sars-cov, while a negative test result does not necessarily rule out sars. , seroconversion of paired serum samples with convalescent serum samples obtained more than days after onset of symptoms is a reliable, sensitive and specific diagnostic method. however, the current diagnostic option of choice for early and rapid diagnosis is rt-pcr detection of virus in respiratory or fecal specimens. this test has low sensitivity, and a negative test result does not exclude the diagnosis. many laboratories are addressing the problem of sensitivity and specificity of the sars diagnostic tests, and it will take some time before a highly sensitive, specific, quick and simple diag-nostic test is available. it is possible that, as is the case with hiv infection, saliva could be used as a diagnostic fluid in this context. many people have been alarmed by the spread of sars in clinical facilities, where a disproportionately large number of health care workers (sometimes up to one-third) have been infected. however, it is reassuring that, to date, there have been no documented cases of sars transmitted in a dental setting. this may be the result of a combination of factors. first, transmission has not been documented during the incubation period before the appearance of febrile symptoms. it is unlikely that patients with sars would visit a dentist for elective treatment while they are in the acute phase of the disease, because of the high fever and other, rather debilitating, attendant symptoms. seto and colleagues conducted a case-control study in which they showed that proper use of standard precautions is adequate to prevent the nosocomial spread of sars in the absence of aerosol-producing procedures. however, as health care providers, dental personnel should be wary of the disease and should know how it is spread, how to identify patients with sars and what modifications need to be made to the practice to prevent transmission of the disease. although sars is well-controlled now, it may emerge insidiously, as has been the case with many other coronavirus infections. we review below the infection control measures that dentists and dental staff members now follow, in light of new epidemiologic data about sars, particularly its spread through aerosols and droplets. our recommendations are based on the recent ada guidelines, the cdc's recent report of recommended infection control practices for dentistry and our own experience in hong kong related to the last outbreak. identification of patients with sars. as health care providers, dentists should be able to identify a suspected case of sars. the cdc's current interim diagnostic criteria for sars are shown in the box. they are subject to change as more is learned about the disease, and should be reviewed periodically by visiting the ada or cdc web sites. to date, there have been no documented cases of severe respiratory syndrome transmitted in a dental setting. as stated above, we doubt that patients with sars who are in the acute febrile phase of the disease will visit a dentist. in the unlikely event that this does occur, the dentist should not treat the patient in the dental office, but should refer him or her to a health care facility as soon as possible for diagnosis and care. dentists also have a duty to report the case to state or local health departments. patient evaluation. as always, dentists should take a thorough medical history from each patient and update it at each recall appointment. the questionnaire used for this purpose may have to be modified to incorporate targeted screening questions regarding sars. although these questions may appear superfluous during the current abeyance of the outbreak, they are important as a guide if there is another outbreak of sars or an outbreak of a similar new disease. these questions may include the following: ddo you have fever? dhave you experienced a recent onset of a respiratory problem, such as a cough or difficulty breathing? dhave you, within the last days (that is, the incubation period for sars), traveled internationally or visited an area where documented or suspected community transmission of sars is occurring? dhave you come into contact with a patient with sars in the past days? in the event that the patient recently has returned from a geographic region with documented or suspected community transmission of sars, the clinician can defer elective treatment until the incubation period is over. dentists can provide emergency treatment, provided they use routine barrier precautions and avoid spatter or aerosol-generating procedures. this emergency treatment should be limited to the control of pain and infection. dentists should not treat patients in the dental office who are suspected of having sars. if a patient replies "yes" to the first two screening questions, the dentist should wear a surgical mask, discuss his or her potential concerns with the patient, call an area medical facility (such as a hospital) and inform the staff that he or she is referring a patient suspected of having sars so that arrangements can be made for transportation and care of the patient. patients with sars need ground emergency medical services. these screening questions should be asked routinely of all patients, because questioning only a select group of patients, for whatever reason, may undermine the early detection of infection and might be construed as a discriminatory practice. clinicians should delay treating convalescing patients for at least one month after they are released from the hospital. convalescing patients are instructed to remain at home for seven days after discharge from the hospital, and during this period they are requested to stay indoors and keep contact with others to a minimum. preprocedural rinsing. a preprocedural antimicrobial mouthrinse (with . to . percent chlorhexidine gluconate) is believed to reduce the number of microbes that are released into the operatory environment. this has been shown in a number of studies in which a longlasting mouthrinse (for example, chlorhexidine gluconate with povidone iodine and essential oils) has reduced the disseminated microbial load during procedures such as ultrasonic scaling. , however, no concrete data show that a preprocedural mouthrinse reduces infection among dental health care workers or patients. a preprocedural rinse would be most useful in situations in which a rubber dam cannot be used, such as when a prophylaxis cup or an ultrasonic scaler is used, and in the absence of assisted, high-volume suction. hand hygiene. microflora on the skin can be divided into two categories: the transient flora colonizing the superficial layers of the skin and mainly acquired through environmental routes, and the residential flora thriving on the deeper layers of the skin and hair follicles. the exogenous, superficial flora are harmful and pathogenic, but are removed easily with clinical hand-washing procedures. by contrast, the endogenous residential flora are almost impossible to remove completely, but are less likely to be associated with infections. the single most important method of preventing transmission of any infectious agent, including the sars coronavirus, is hand washing and appropriate hand care. studies have found that even in critical care units, hand-washing compliance is relatively low, sometimes approaching percent. by contrast, a dramatic reduction in the prevalence of health careassociated infections has been shown when regimented hand hygiene measures were introduced. thus, appropriate hand hygiene is the mainstay of a good dental infection control program. furthermore, recent data indicate that the sars virus, compared with other coronaviruses, is a relatively robust organism and may survive on nonporous surfaces for up to hours. this reinforces the need for good hand hygiene, as well as the importance of thorough surface disinfection. hand hygiene for routine dentistry. for routine dentistry, which entails examinations and nonsurgical procedures, plain soap and water are adequate. recently, the cdc recommended that if the health care worker's hands are not visibly soiled, an alcohol-based hand rub could be used for routine decontamination, because this is as effective as hand washing and also saves time. also, clinicians should decontaminate their hands both before and after removing gloves, because humidity and moisture cause bacteria to multiply rapidly under the glove surface. hand rubs that are based on alcohol alone should not be used owing to their rapid evaporation and lack of residual effect. consequently, hand rubs must be laced with agents such as chlorhexidine, octenidine or triclosan to achieve the needed effect. after using an alcohol-based hand rub, the clinician must dry his or her hands thoroughly before putting on gloves, because any residual alcohol may increase the risk of glove perforation. personal protective equipment. personal protective equipment, or ppe, is designed to protect the skin and mucous membranes of the eyes, nose and mouth from exposure to potentially infectious material. recent experience with the sars coronavirus has shown that vast numbers of health care workers acquired the infection in hospital settings, either as a result of inadequate barrier protection methods or the improper use of these methods. this barrier protection equipment consists of protective eyewear, masks, gloves, face shields and protective overwear. we should note that general work clothes such as uniforms do not protect against a hazard and should not be considered ppe. we describe below the relevant aspects of ppe that pertain to protection against airborne hazards. masks. face masks were first worn by surgeons to minimize postsurgical infection in patients due to microbes that were exhaled or shed by the surgical team. however, the realization that face masks protect the health care worker as well as the patient has led to the routine use of this protective measure in many clinical settings including dentistry. transmission of airborne infection depends on factors such as the virulence of the organism, as well as the number of organisms, transmitted. in the case of coronavirus-induced pneumonia leading to sars, airborne droplet transmission of infection is considered to be the main route of spread. various types of masks and face shields are available. surgical masks usually provide adequate protection in dental care settings, where highly transmissible infectious diseases are not typically encountered. particulate respirators. however, surgical masks are not designed to provide adequate protection against exposure to airborne infectious agents such as tubercle bacilli or droplet nuclei smaller than micrometers. for such purposes, particulate respirators (for example, n- masks) must be used. during the sars outbreak in hong kong, the vast majority of dental practitioners in that country used n masks for routine dentistry. however, these masks are uncomfortable to wear for extended periods because of the difficulty in breathing through a thick impervious fabric, and are not recommended for routine dental office settings. rubber dam isolation. rubber dams help minimize the production of saliva-and bloodcontaminated aerosol or spatter. samaranayake and colleagues reported an up-to- -percent reduction in airborne particles around a -foot diameter of the operational field when a rubber dam was used. a split-dam technique may be used in situations in which gingival areas are involved, such as class v restorations and crownand-bridge preparations. aerosol-generating procedures should be avoided as much as possible if rubber dam isolation is not feasible. some of these procedures include ultrasonic scaling, root-surface débride- ment, and high-or low-speed drilling with water spray. there is no doubt that coronavirus research has gained an unprecedented and urgent momentum owing to the lethality of sars and its nearly worldwide spread within a few months. consequently, laboratories throughout the world are working in unison to provide answers to many unresolved questions, as well as to develop a new preventive vaccine. in dentistry, in particular, a number of questions remain to be resolved, including the following: although the global threat of sars has peaked for the most part, it is helpful to review the response of the community to this novel disease. it is fortunate that sars was not sufficiently infective to cause a repeat of the influenza pandemic that killed millions. even so, we might be able to attribute the relatively low death rate in large part to the worldwide surveillance networks and patient isolation efforts that were introduced rapidly in most countries. in retrospect, an overreaction seems to have been a better option than allowing the disease to run out of control, as was the case with the aids pandemic. culmination of the outbreak. the who lifted all its travel advisories as of june , , and since then, only three new cases of sars have been reported. two of these-one in singapore and the other in taiwan-were acci-dental, laboratory-acquired infections in research technicians working with the organism, while the third patient-from guangdong province in southern china-is thought to have acquired the infection through contact with contaminated rodents. because the initial symptoms of sars mimic those of many variants of atypical pneumonia, a high degree of suspicion by the medical establishment, intense surveillance and immediate quarantine of all close contacts of patients should ward off another, large-scale winter outbreak. if sars does return, its epidemiology may be different from that of the current strain. for instance, the genome of the new sars-cov may differ, and the virus may be more or less infective than the original strain that emerged in . furthermore, we do not know how long the acquired immunity to sars persists. also, will those exposed to the virus be carriers of the disease in the face of a new infection? how many will be silent healthy carriers of the virus? will an emergent strain or strains behave similarly to the older counterpart? we do not have the answers to these questions. mutation of the sars-cov. the reason for the pandemic spread of hiv is its ability to mutate rapidly from one generation to another so it can escape the immune surveillance mechanisms of the host, as well as the prescribed antiviral medications. the sars virus, on the other hand, seems to be remarkably invariant; the genome sequence of isolates from patients in singapore, toronto, china and hong kong has not revealed any changes of major consequence. this does not mean that the sars virus is incapable of mutation; rather, because the virus has encountered little resistance from new human hosts, there is less selective pressure for new mutants to emerge and persist. drugs and vaccines for sars. many researchers are working on potential drugs and vaccines to treat patients with sars. however, their approach has been scattered for the most part, as they screen the multitude of available drugs and compounds for their ability to destroy the sars-cov. thus far, a few have had success. one group reported that the compound glycrrhizin, which is derived from licorice roots, can rid cultured monkey kidney cells of the sars virus. other researchers, using in silico research, have proposed that the newly described proteinase of the sars virus (which converts viral proteins into the active form required for viral replication) could be inhibited by drugs. animal models are essential for experimentation and drug discovery; thus far, the only validated model has been cynomolgus macaque (macaca fascicularis). a smaller and less expensive animal model for sars research has yet to be defined. although vaccines exist for animal coronavirus infections, it may take a few years before a vaccine for sars is developed. it is comforting to note that the existing technology and know-how for animal coronavirus vaccines could be translated directly toward the manufacture of a sars vaccine. furthermore, implicit evidence shows that the vaccine approach to preventing sars is feasible, because patients' conditions appear to improve when they are given hyperimmune serum from recovered patients with sars. sars vaccines could be based on a killed sars virus or on an attenuated virus that is sufficiently potent to replicate itself in humans and initiate a successful antibody response, but not potent enough to cause disease. another option would be to re-engineer a harmless candidate virus to contain genetic sequences of the sars virus. this approach has been used to produce a prototypic vaccine against a coronavirus that causes bronchitis in chickens. should there be a renewed threat of sars, a vaccine would be a mostwelcomed weapon by health care workers. sars is the first readily transmissible infectious disease that the global community has confronted in the new millennium. this, surely, will not be the last contagion that we will encounter. the fact that no dental health care worker or dental patient has thus far contracted sars in a dental setting is a testament to good infection control measures that have been implemented in the vast majority of dental offices. however, the dental community cannot let down its guard, and must be constantly aware of impending infectious threats in various guises, as well as recrudescence of disease, that may challenge the current infection control regimen. i institute of medicine; . . samaranayake lp, peiris js, scully c. ebola virus infection: an overview the ebola virus and the challenges to health research in africa west nile virus: statistics, surveillance, and control. available at infection control for the dental team cumulative number of reported probable cases of severe acute respiratory syndrome (sars) there is nothing permanent except change: the emergence of new virus diseases centers for disease control and prevention. isolation of avian influenza a (h n ) viruses from humans: hong kong epidemiological determinants of spread of causal agent of severe acute respiratory syndrome in hong kong clinical presentations and outcome of severe acute respiratory syndrome in children sars: what do we know about the disease updated interim u.s. case definition for severe acute respiratory syndrome (sars) (appendix b ) sars bulletin from hong kong coronavirus as a possible cause of severe acute respiratory syndrome identification of a novel coronavirus in patients with severe acute respiratory syndrome sars-associated coronavirus koch's postulates fulfilled for sars virus coronaviruses of man isolation and characterization of viruses related to the sars coronavirus from animals in southern china identification of severe acute respiratory syndrome in canada comparative full length sequence analysis of sars coronavirus isolates and common mutations associated with putative origins of infection centers for disease control and prevention. interim domestic infection control precautions for aerosol-generating procedures on c l i n i c a l p r a c t i c e patients with severe acute respiratory syndrome (sars) effectiveness of precautions against droplets and contact in prevention of nosocomial transmission of severe acute respiratory syndrome (sars) world health organization. who hospital discharge and followup policy for patients who have been diagnosed with severe acute respiratory syndrome (sars) reduction of viable bacteria in dental aerosols by preprocedural rinsing with an antiseptic mouthrinse reduction of bacteria-containing spray produced during ultrasonic scaling essential microbiology for dentistry how good are hand-washing practices? world health organization. summary on major findings in relation to coronavirus by members of the who multicenter collaborative network on sars aetiology and diagnosis. available at healthcare infection control practices advisory committee, hicpac/shea/apic/idsa hand hygiene task force. guideline for hand hygiene in health-care settings: recommendations of the healthcare infection control practices advisory committee and the hicpac/shea/apic/idsa hand hygiene task force: society for healthcare epidemiology of america/association for professionals in infection control/infectious diseases society of america hospital epidemiology and infection control the integrity of latex gloves in clinical practice the surgical mask unmasked: a review medical progress: how contagious are common respiratory tract infections? evidence of airborne transmission of the severe acute respiratory syndrome virus the efficacy of rubber dam isolation in reducing atmospheric bacterial contamination sars: breaking the chains of transmission chemical modification of glycyrrhzic acid as a route to new bioactive compounds for medicine coronavirus main proteinase ( clpro) structure: basis for design of anti-sars drugs a recombinant fowl adenovirus expressing the s gene of infectious bronchitis virus protects against challenge with infectious bronchitis virus dr. peiris is a professor of virology, faculty of medicine, the university of hong kong, hong kong, and the chief clinical virologist, queen mary hospital, hong kong. key: cord- - cc r authors: laurie lau, yiu chung title: cybercrime in cloud: risks and responses in hong kong, singapore date: - - journal: the cloud security ecosystem doi: . /b - - - - . - sha: doc_id: cord_uid: cc r the popularity and commercialization of the “internetwork” began in the late s through the interconnection of computer networks using special gateways or routers to transfer packets of electronic data. as with many things in life, internetwork technology has had both positive and negative effects on society, and asia has been no exception. one of the negative effects has been a surge in internet crime. according to a report released by the gartner consulting group, in smart phone sales exceeded regular phone sales for the first time, with million smart phones sold, representing % of the global mobile phone total and an increase of % from . the popularity and technology of the mobile internetwork, especially the smart mobile phone web, has changed the internetwork landscape through the concept of cloud computing. cloud computing is distributed computing over a network, using a program or application that can run on many connected computers and in different locations around the globe simultaneously at a reduced cost. this distributed cloud computing presents law enforcement authorities with the unique challenge of policing internet crime. cloud computing relies on sharing resources to achieve coherence, and in doing so creates economies of scale for converged infrastructures and shared services. accordingly, one problem facing the authorities is the presence of trans- and multijurisdictional crimes. in this chapter, i explore this topic in the contexts of hong kong and singapore, as both are key players on the international stage, especially in relation to international finance and information technology. in both locations, infrastructure works to maintain global financial center status. the remainder of this chapter is organized as follows. a brief overview of the development of cloud computing is followed by an examination of cybercrime risks in the cloud. then, i review how the authorities in hong kong and singapore respond to cybercrime risks and explore the current government policies on cloud computing, particularly in fighting cybercrime. although the term "cloud computing" has already been used elsewhere in this publication, for ease of understanding, in this chapter i follow the model used by quick et al. in their book, cloud storage forensics. basically, cloud computing comprises three models: cloud iaas: this provides clients with access to storage space, bandwidth, and other fundamental computing services. it effectively expands the computing capability of the customer, allowing them to run their own software and applications using the cloud infrastructure; cloud paas: this allows the customer to gain access to the computer platform or operating systems of the cloud instances (e.g. windows and linux) and an underlying database so that they can create or acquire applications; cloud saas: this allows clients of the csp to utilize software and applications running on the cloud infrastructure. the applications are accessed via remote computers and mobile devices using the appropriate cloud interface software. the consumer's device acts like a portal to the software and data stored in the cloud. however, describing cloud computing crime in simple terms has been a challenge ever since the early days of the internetwork revolution. a variety of terms are used when explaining the criminality associated with the popularity and commercialization of information communication technology (ict), including "new technology crime," "online crime," "cybercrime," and "internet crime." these terms tend to be used interchangeably, which makes it difficult to provide universal definitions. ict is constantly evolving along with the associated criminality, including cloud computing crime. in addition, certain types of online activities considered to be "internet" or "cloud computing" crime in some countries are not considered as such in others. for example, in most western common law countries, if a female posts topless beach holiday "selfies" on facebook via a smart mobile phone to share among friends, the act would be considered a harmless private activity. in many muslim countries, and certainly those in the middle east, however, the act would be considered a criminal offense; the woman would be subject to criminal prosecution in court and the act would be punishable by public lashing. both polity and invested interests are at play, and the novelty of the "risk" or "threat" posed by new forms of technology-associated crimes can be used to support a larger share of government funding. cloud computing crime has become a broad term that embraces all forms of digital crime such as television and film piracy and location-based smart mobile phone crime. the growth and development of cloud computing crime has largely been a consequence of the expansion of cloud computing environments capable of facilitating criminality. thus, for the purposes of this chapter, "cloud computing crime" is any criminality committed with the aid of recognized cloud computing models, including the smart mobile phone operation system model. in recent years, places such as hong kong, singapore, and other parts of asia have witnessed noticeable growth in cloud computing. the popularity of smaller mobile computing devices such as smart phones, which have resulted from advancements in internet technologies, has been combined with the nature of cloud computing, which provides faster, easier access to files in remote locations, to allow users to access and update files on the move. although cloud computing technologies offer efficiency in terms of users' hardware requirements and access barriers, they also create challenges for both law enforcement authorities and individuals alike. one such issue is the policing of computer-related crime, which involves gathering evidence from, storing data in, the cloud, and then prosecuting the perpetrator. scholars have drawn attention to some of these issues, but the socio-legal perspective treated here has not received much attention in the literature to date. policing priority is typically set by country or place individually according to their needs. factors affecting policing include the economy, legal traditions, police structure and organization, cultural factors, and political structure. the protection of these factors and their perceived importance is different in each jurisdiction and under each government in power, and thus policing varies accordingly. this phenomenon is also true for policing the internetwork, as the development and level of information technology (it) access and infrastructures differ in different parts of the world. for instance, in accordance with the united nation international telecommunication union (unitu) report on the digital divide in , it disparities in terms of access to information and communication technology are pronounced between the developed western economies such as those of america, canada, and western european countries (this group includes a few advanced economies in asia such as those of japan, south korea, singapore, and hong kong), and the lessdeveloped economies such as those of northern africa, latin america, pacific ocean islands, and some parts of south eastern asia. the level of policing for the internetwork is also different, as each country prompts different government perceptions of its level of technology risk or economic threat. these perceptions are largely dependent on the level of technology each country relies on to generate wealth, and sometimes on how much a given government sees technology as a threat to its political structure and systems. thus, technology policing is prioritized differently from country to country. however, the same unitu report stressed that the digital divide had closed significantly between developed and developing nations, particularly in south east asia and numerous african countries due to the increase in portable devices such as smart phones and the decrease in their cost. as international telecommunication union (itu) director brahima sanou said: the surge in numbers of mobile-broadband subscriptions in developing countries has brought the internet to a multitude of new users. despite the downward trend, prices remain relatively high in many low-income countries. for mobile broadband to replicate the mobile-cellular miracle and bring more people from developing countries online, g network coverage has to be extended and prices have to go down even further. . . . mobile-cellular subscriptions registered continuous double-digit growth in developing country markets, for a global total of six billion mobile subscriptions by end . . . noting that china and india each account for around one billion subscriptions. mobile broadband continues to be the ict service displaying the sharpest growth rates. over the past year, growth in mobilebroadband services continued at per cent globally and per cent in developing countries. there are now twice as many mobile-broadband subscriptions as fixedbroadband subscriptions worldwide. the increased ownership of smart phones in these countries has not only narrowed the gap between them and traditional fixed-location devices such as desktop computers, but also shifted the information and communication technology landscape. the technique of virtualization in cloud computing has created an economy of scale, such that services are only provided when there is consumer demand. this allows service providers to reduce their materials and service costs. on one hand, almost all smart phone devices now allow users to constantly connect with the internetwork on the go; anytime, anywhere. on the other hand, to enhance the user's smart mobile phone experience, service providers must design their services based on users' needs. this can result in compromised safe-guards and security, which in turn create opportunities for criminal activity, and authorities have yet to catch up to these technologies, especially when perpetrators can be located overseas or in different police jurisdictions. the increase in mobile smart phone use has also been rapid and significant in singapore and hong kong. to put it in perspective, according to the nielsen smart phone report in , both hong kong and singapore were ranked at the top for smart phone penetration rate in the asia pacific region, with more than % of their populations owning smart mobile phones. as sagar phadke, director of nielsen's telecom and technology practice in southeast asia, north asia, and the pacific said: the growth in connected device ownership across asia pacific has been staggering in recent years. while this growth is expected to begin levelling out, consumers' use of connected devices will continue to evolve and expand, presenting vast opportunities for organisations to engage with consumers on an almost ubiquitous platform. it is becoming more critical than ever for companies to develop sophisticated mobile strategies designed to leverage changing connected device behaviours and develop ongoing consumer engagement. there has been an ample and growing opportunity for smart phone commerce in fields such as mobile banking, games and videos, and advertising in the asia pacific region, particularly in hong kong and singapore. however, the rapid increase in smart phone use and penetration has greatly increased the potential for corresponding growth in smart mobile phone crime. for example, according to a kpmg international report on cybercrime, cybercriminals are moving beyond desktop computers to target smart mobile phones and other mobile devices. the report stated that in the previous years, digital crimes specifically targeting mobile devices had risen %. although the actual level of smart mobile phone crime is not known, and what is known is probably just the tip of the iceberg, the potential for problems is sobering. what follows are examples of smart phone crime in hong kong and singapore. in hong kong, a local chinese newspaper reported that during the world cup, the hong kong police noticed that betting on illegal football matches through mobile phone apps increased. mobile apps have also been used to sell counterfeit goods in hong kong. in a joint operation between customs and excise and the police in april in the tsim sha tsui area, people were arrested and items of suspected counterfeit goods valued at hk$ , were seized. in july , a similar operation was mounted by the hong kong authorities and people ( of whom were younger than ) were arrested and goods valued at about hk $ , were seized. according to hong kong authorities, in the first months of the number of people arrested who are younger than has risen by % compared to the same period in . in these cases, most of the young offenders participated in the sale of suspected counterfeit goods on internet platforms via mobile phones, through auction sites or social networks, during their leisure time. other types of crime have been committed using smart mobile phones. in january , according to paul gordon, sai kung divisional commander, thieves used surveillance cameras to monitor their targets instead of doing their own reconnaissance: a device will be fixed outside a house and linked to their [smart]-mobile phones, to monitor when it is left unattended. then they will take the chance to break in. the device was low-tech and could be bought cheaply in the sham shui po electronics market. but it was the first time police had seen it used in this kind of crime. in singapore, for example, according to a report released by websynergies, there have been a million singaporean cybercrime victims. the report estimated a total of us$ billion lost through cybercrime over the period of a year. smart mobile phones have become the tool of choice for cybercriminals in singapore, as viruses can migrate from personal computers (pcs) to mobile devices. the incidence of related petty crimes such as smart phone snatching has also risen. in another example from singapore, channel news asia interviewed an inspector of the singapore police. during the live interview, conducted on april , , the inspector described a smart mobile phone crime case involving a woman in her late s who was an accountant by profession. she allegedly befriended a male who claimed to be a pilot for singapore airline. they met and chatted on whatsapp through their smart phones for some time, and ultimately agreed to meet face-to-face in a café near the singapore international airport. the supposed pilot told the woman that he had been in a hurry to get out of his flat and had forgotten to bring enough euros with him. he asked the woman if she would transfer singapore dollars to a certain bank account under his name, so that when he landed in germany the next day he could withdraw the cash from an atm. he promised to repay her in a week's time, when he returned. the woman agreed and transferred the money via her smart phone. for some time, she did not hear from the man and could not contact him on whatsapp. after months she reported him to the police. the man was eventually arrested wearing a pilot's uniform near the international airport, in a sting operation mounted by the police after a few more women fell victim to his scam and reported him. we only know about these cloud computing-enabled smart mobile phone crimes because they were in the public domain, but the true level of such crime remains unclear. the lack of reports on cloud computing crime is probably related to the fact that cloud computing is a relatively new concept for law enforcement authorities. the term was only coined in the late s. victims of cloud computing crime might not even realize their status as such, or they may choose not to report it, as the police are sometimes unable to recognize it as such and instead record it as traditional street crime. even when the police recognize and record an event as cloud computing crime, they may have difficulty following up, especially if the servers and data involved are located overseas or in multiple jurisdictions. as quick et al. explain, "the key component of cloud computing is multi-tenancy capability, which is referred to as a shared pool of resources . . . individual files may be distributed across multiple disks and storage systems across multiple jurisdictions." securing and preserving a chain of evidence for prosecution in court involves significant police resources, and even if the culprit is deported to face justice, the case may not pass the prosecution's test of public interest and the perpetrator could escape justice. key factors shaping "response": hong kong, singapore . hong kong hong kong, founded by the british for trade purposes, was a british colony for over years before it was restored to the people's republic of china (prc) on july , . as an entrepot and capitalist enclave without natural resources, hong kong's economy has largely been dependent on international and interregional trade. in the intermittent period between the s and the early s, hong kong was labeled a sweat-shop for the world's light manufactured goods, but with the open-door policy introduced by communist china in , hong kong industrialization came to an abrupt end in the early s. almost all of the manufacturing factories were moved northward across the border to shenzhen city or beyond in mainland china, due to cheaper wages and land. by this time, hong kong was beginning to establish itself as a financial center and professional services hub, largely serving the booming mainland china economy supported by the open-door policy and the growth of the asian economy. by the beginning of the twenty-first century, hong kong had become well established as the fourth largest global financial and banking center in the region. over % of hong kong's gross domestic product (gdp) is generated from nonmanufacturing-related industries, including banking, financial and professional services, and retail. see quick et al. ( , p. ) . entrepot is a term use to describe a place where merchandise can be imported and exported without paying duties or tax, therefore the profit is being maximize. without other industries to generate wealth for hong kong, what is left is its status as an international financial center and its professional service-based industry, both of which are highly dependent on modern ict to operate from, protect, and maintain the integrity of hong kong's ict infrastructure. to its advantage, culturally, hong kong has been very receptive to newer technologies. the rapid adoption rate of smart mobile phones is one example. this is partially due to the fact that most new technology is manufactured in asia, and thus the closest source of production is relatively cheap to purchase. hong kong's per capita income is also relatively high (at us$ , in ), and that wealth and purchasing power means the general population can afford to buy newly marketed technology rapidly, and as such they have become increasingly technologically savvy. for example, hong kong was one of only a few places on the globe to launch apple's iphone in august . hong kong's political structure reflects its legacy as a british colony. characterized as a semiauthoritarian city state, hong kong did not become a democracy after its return to the prc in . although there is currently an ongoing debate in hong kong over the democratic election (supposedly one man, one vote) of the chief executive of the hong kong government special administrative region in , things remain uncertain because beijing is wary about democracy in hong kong out of a fear that it might become a base for subversion to undermine the communist party rule in mainland china. hong kong's governmental decision making is semiauthoritarian and top-down in nature, and the selection of the chief executive (formerly governor) is tightly controlled from beijing. only members of a select committee are allowed to vote in the chief executive election, and a great majority of them are pro-beijing merchants and professionals. the first chief executive was a well-known shipping tycoon, and the man who currently holds the office is also a well-known professional-turnedmerchant. the hong kong executive councilors (the executive branch of government policy decision-making body, who act as a cabinet to the government) are largely appointed from a pool of merchants and professionals. government policy does not answer to the public, and the general population does not vote the government into power. policy answers only to hong kong's tycoons the small number of select committee members and the political master in beijing. ultimately, government policy's priority is to protect and reflect the interests of the ruling elite and their supporters, rather than those of the general public, because the latter does not vote. since hong kong's reintegration with china in , there have been fears that some of the former's core values are being threatened, such as the erosion of rule of law due to the ways in which things are done in mainland china (corruption, nepotism, gangsterism, and the use of power and connections to avoid the law). some events have been cause for concern in hong kong. for example, beijing interpreted the basic law (the mini constitutional law of hong kong) in the late s and early s, but the major clash between beijing and hong kong over the rule of law occurred in , when beijing instructed hong kong's government to introduce article into the basic law to regulate subversion. article is similar to the national security laws in many western countries, but the very idea of such a law was new to postcolonial hong kong, and given the chinese communist party and the chinese government's track record, it sent chills down the spines of many in hong kong. the legislative process for article triggered a mass public outcry, with over half a million people protesting in the streets against the legislation. eventually, hong kong's government put the national security bill on hold indefinitely, temporarily shielding the rule of law in hong kong from being "mainlandized." however, the "mainlandization" of hong kong has accelerated, especially since , after a series of crises including the asian financial crisis in and the avian flu and severe acute respiratory syndrome outbreaks. these crises prompted hong kong to actively seek help from the mainland and push for greater economic integration. the closer economic partnership arrangement between mainland china and hong kong is a case in point. politically, it is in beijing's interest to help hong kong, as it would be seen as a failure for beijing if hong kong failed only a few years after reintegration. these factors have helped to accelerate the pace of hong kong's integration with the mainland, both politically and economically. hong kong's police force, as an arm of the government established in the early s, is directly funded by the government. the commissioner of police is appointed by and answers directly to the chief executive. the police force as a whole is directly accountable to the government officials at the security bureau. the commissioner of police, government officials, and the chief executive can be called before the legislative council to explain their decisions on issues relating to policing, but because hong kong is not a democratic society, the priorities for policing in hong kong are not set by election manifesto. thus, policing priorities are more likely to reflect the interests of the officials at the highest level of government than those of the general public. as a former british colony, hong kong is founded on common law. the main piece of legislation on computer-related crime is the computer crimes ordinance of . according to a report released by the hong kong interdepartment working group on computer-related crime, the computer crimes ordinance was instituted by amending existing laws and creating some new offenses to broaden the coverage of the extant legislation. hong kong's computer-related crime legislation is sufficiently flexible to cover both the physical and the virtual worlds. like hong kong, singapore was also part of the british empire. however, unlike hong kong, singapore gained independence from malaysia in the late s as a fully sovereign nation. singapore's economy is also different from that of hong kong. it comprises manufacturing (including hi-tech manufacturing and r&d), biotechnology, pharmaceuticals, electronics, technology and telecommunications, import and export, oil refinery, shipping and transport (south east asian hub), financial and banking services and professional services, and retail. almost % of singapore's export trades are interregional: malaysia ( . %), hong kong ( . %), mainland china ( . %), indonesia ( . %), and japan ( . %). hence, singapore economy is diverse. as an independent nation, singapore's clear advantage over hong kong is that she does not answer to a political master and is free to decide her own economic policy. one benefit of this is singapore's technological policy. from early on in its independence, singapore's government has exploited technology as leverage for economic development. as a result, singapore's economy has improved by adopting technology as its bedrock to upgrade industries across the economy. meanwhile, singapore's government has directly nurtured new technology-based industries, especially in the economy's indigenous sectors such as it, biotechnology, microelectronics, robotics and artificial intelligence, lasers/optics, and communications technology. the establishment of infocomm development authority (ida) of singapore is a case in point. as connie carter put it: few can doubt that singapore is a successful example of a growth-oriented, interventionist, capitalist state . . . for four decades the singapore government resolutely promoted economic development by: providing free market access to certain things; establishing and maintaining efficient infrastructure; orchestrating and investing in key export-led sectors of the economy; disciplining and educating the work force; and creating an ideology and delivering social justice and tangible benefits that secure the acquiescence of the people to the activities of the state and its elite bureaucrats. singapore's technological economy policy not only directly rewards indigenous sectors for innovation and high-tech adoption, but singaporean society at large also benefits from this technology-focused economy policy by being receptive to newer technology and becoming early adopters of high-tech products. the high penetration rate of the latest smart mobile phone is such an example. unlike hong kong, singapore is not dependent on a single industry to generate wealth. despite being capitalist and unlike hong kong, whose government is not directly involved in the economy, the singaporean government is deeply involved in the economy. in singapore, the domestic economy is largely dominated by two sovereign wealth funds: temasek holdings and gic private limited (formerly known as government of singapore investment corporation, gic). they are used to manage the country's reserves. initially, the state's role was oriented more toward managing industries for economic development, but in recent decades the objectives of singapore's sovereign wealth funds have shifted to a commercial basis. as a result, in recent years, government-linked corporations (glcs) have played an increasingly substantial role in singapore's domestic economy. the top six singapore-listed glcs account for about % of total capitalization of the singapore exchange. these fully and partially state-owned enterprises operate on a commercial basis and are granted no competitive advantage over privately owned enterprises. state ownership is prominent in strategic sectors of the economy, including telecommunications, media, public transportation, defense, ports, airport operations and banking, shipping, airlines, infrastructure, and real estate. for example, ida is the singaporean government's invisible hand-a statutory board of the singapore government under the ministry of communications and information. it was formed in when the government merged the national computer board and telecommunication authority of singapore to facilitate the convergence of it and telephony. with an annual budget of more than s$ million, the ida is responsible for the development and growth of the infocomm sector in singapore, and it functions as the country's infocomm industry champion, the national infocomm master planner and developer, and the government chief information officer. the ida's most recent project has been intelligent nation , a -year master plan. singapore is aiming to be the first nation in asia to be considered an it-related "smart nation." in , singapore has achieved a number of top benchmarks, including having the most digitized government (with % of government services online and in the cloud and more that % of singapore's information technology and communication (itc) in the cloud) and being the most networked country in the world (with % of the school-age population reporting access to a computer at home and % of households reporting access to broadband). like hong kong, singapore is also very receptive to newer technology, and its population is technologically savvy. the british broadcasting corporation (bbc) has profiled singapore as ". . . a hi-tech, wealthy city-state in south-east asia." singapore's per capita income is also relatively high (at us$ , in ). with this kind of wealth and purchasing power, the latest technological products are easily afforded by the general population. however, unlike hong kong, singapore is recognized by its government as a multiracial society with different ethnicities (chinese is the majority at almost %, with the rest of the population comprising those of malay and indian heritage). singapore's government has managed its society carefully, through social engineering of ethnicity and by providing subsidy housing (today over % of the population is housed through the government housing scheme) and socially engineering education, particularly that with an english language base. this has transformed singapore from a society once characterized by sharp contrast between ethnic groups who spoke different dialects and were separated by a large wealth gap into an affluent, english-speaking, middle-class industrialized metropolis. this has made singapore culturally different from many of its neighbors in south east asia, with the former being more in tune with technological development around the world because english is the common language used in commerce and in top scientific publications. thus, singapore has had an easy time acquiring newer technological knowledge and upgrading their skills. in theory, unlike hong kong, singapore is a democratic nation state with a parliament based on the westminster model. the government is voted into office via a one man-one vote election process. every years there are free and fair elections. the majority party or coalition gets to choose the prime minister, who then selects his/her cabinet of ministers. however, in practice, there is a similarity between hong kong and singapore. as vadaketh explains, "singapore has been governed as an authoritarian state. one party, the people action party (pap), dominates parliament." democracy in singapore, however, is "singapore style" or "asian democracy" whereby political power is in the hands of few singaporean elites. this "elite governance" or, more importantly the pap, has been active since for almost years. decision making is largely a top-down process because there is little-tono opposition in the parliament. as low said, "the pap government has viewed the economy and society as machines," and since pap came to power, its legitimacy has largely been gained through a strategy of social pacification and the institution of repression and redistribution. however, in recent years the pap suffered a setback in the popularity vote at the general election, only receiving . %, which was down % from the general election in . pap is facing the call for legitimacy in the government. nonetheless, with more than % of the popular vote, pap is still firmly in power. policymaking is largely pursuing economic growth, and anything else is a secondary consideration for the pap government, as they believe that economic growth would benefit most segments of society. like hong kong, singapore was a british colony, and thus it has a common law tradition and a court system similar to that of hong kong, with a court of appeals at the top (equivalent to the court of final appeal in hong kong, since july , ), then the high court and the subordinate courts such as district, magistrates', etc. however, the foundation of singapore's penal code is different from that of hong kong's, as the former was taken from india's penal code in its exact entirety and gradually developed a local flavor. another difference is the syariah court, which hong kong does not possess. one of the important first local pieces of legislation was the criminal procedure ordinance of , which was subsequently revised in . over time, various criminal laws were enacted. one of the most relevant to it was the computer misuse act, amended in . although singapore's computer misuse act followed the english act, one noteworthy difference from the hong kong computer crime ordinance is that the offense created by the singapore act has extraterritorial effects, as chan and phang explain: provided either the accused person was in singapore at the time or if the computer, program or data was in singapore at the time. this is in recognition of the widespread reliance on computer technology all over the world and its vulnerability to manipulation either from within our shores or abroad. as a former british colony, singapore's criminal justice system is a punitive regime with no jury at court trial and punishment based on hard labor. the prison system is designed to be as degrading as possible, and public caning is not a rare punishment for wrongdoers. although singapore's prison system has been reformed in recent years with the introduction of concepts such as restorative justice, rehabilitation, education and training, the police, courts, and other regulatory agencies still take a hard line on crimes by "nipping them the bud" as a deterrent to others. according to the bitglass cloud adoption report published in august , over % of businesses are still hesitant to transfer their data to the cloud due to security risk concerns that are largely about the cloud core architect of leveraging on virtualization. for example, dropbox for android smart phones uses cloud technology, and each time see chan and phang ( , p. ) . the singapore syariah court was established in by the government as an institution in settling disputes between divorcing muslim couple and related matters, such as maintenance, mut'ahconsolatory gift payable to the ex-wife upon divorce, custody care control and access to children, and matrimonial property (see syariah court singapore). chan and phang ( , p. ) . see bitglass, . data are delivered over the internetwork through different telecommunication channels, the data are virtualized, leaving the user unaware of which servers are involved or which host is delivering and its location, because the cloud only delivers a minimum volume of data stored for any given client. businesses that worry about data integrity and that fear losing their sensitive data have questioned whether their data are protected from outsiders and from other tenants sharing the same cloud data center. small business is especially vulnerable to this, as australian institute of criminology research in (hutchings et al., ) shows that small business is vulnerable to side channel attack or cross-guest virtual machine breaches, because in cloud, resources are shared with different tenants at the same cloud data center. as a result, tenants might crossing the shared virtual machine segment and accessing the data of other tenants using shared physical resources. more importantly, the same research has identified that small business is more vulnerable because they operate in highly financially constrained environment when compared with larger "global multinational" business, yet they are induced by the promise of cloud computing to save on their ict overhead. as hutchings et al. said "however, in adopting cloud computing, it is this distinct operating environment that also renders small businesses vulnerable to criminal and security threats [once attack happened some small businesses might not able to recover from it and the business could possibly come to abruptly end]." nevertheless, nearly % of the businesses in hong kong and in singapore are regarded as small businesses employing less than people. interestingly, users also wonder whether the data are protected from the cloud provider. cloud computing is largely modeled on the demand for access to a shared pool of configurable computing resources such as networks, servers, storage, applications, and services. all such resource sharing is to ensure fast provision and saving on costs. for example, us researchers were able to hack into gmail accounts with a % success rate by exploiting a weakness in smart mobile phone memory. the same research also found that once a smart mobile phone memory has been exploited, there is a great risk of collateral damage to other mobile apps on the same smart phone. as zhiyun qian said: the assumption has always been that these apps can't interfere with [each] other easily, but such assumption was wrong, one app can in fact significantly impact another and result in harmful consequences for the user. although in theory hong kong and singapore are exposed to similar risks and threats in the cloud, their level of readiness depends on how they perceive risk, as each individual jurisdiction interprets and responds to risk differently according to their unique policing needs. for example, hong kong would react strongly if its economy was threatened, particularly banking, financial, and professional services, because see hutchings et al. ( , p. ) . hutchings et al. ( , p. ) . see bbc news ( ). they represent the only industries by which wealth is generated. hong kong's reputation as an international financial center is dependent on the integrity of its ict. thus, the hong kong police keep a watchful eye on the it infrastructure to maintain foreign investor confident in hong kong, which creates employment and facilitates the payment of government taxes. furthermore, as a part of china since , hong kong must consider internal national politics, such as the growing threat of the separatist terrorism group from the xinjiang region. in nevertheless, the current setup of tcd, with limited manpower and as a division within the ccb, is not able to meet the challenges of the increasingly sophisticated technology crimes and cyber security threats, not to mention the constant support provided by tcd to other formations of the police in various cases, such as death inquest and locating missing persons. today, hong kong has one of the highest concentrations of wi-fi hotspots in the world, and % of households are able to access to broadband services. with a high mobile phone penetration rate of % which is expected to grow further, individuals, corporates, and critical infrastructure are prone to technology crimes and cyber security threats. subsequently, a more dedicated police formation "organization and structure" is needed to tackle the fast growing technology crime trend, including smart mobile phone crime: . . . to tackle the fast growing technology crime trend have become one of the operational priorities of the hkpf. given the rapid advancement in information technology and the transnational nature of technology crime, there is a pressing need to strengthen the overall capability of the hkpf in combating technology crime and cyber security incidents. hong kong's police have carefully explained their strategies to the legislative councilors, to take effect once the new technology crime bureau is established in early : dedicated attention and strategic planning to tackle the fast growing technology crime trend have become one of the operational priorities of the hkpf. given the rapid advancement in information technology and the transnational nature of technology crime, there is a pressing need to strengthen the overall capability of the hkpf in combating technology crime and cyber security incidents. with the establishment of a new bureau dedicated to the prevention and detection of technology crime and protection of cyber security, the hkpf's capability in combating technology crime and handling cyber security incidents will be greatly enhanced through the formulation of long-term objectives and strategies and expanded and dedicated efforts in the following areasi) detecting syndicated and highly sophisticated technology crimes and conducting proactive intelligence-led investigation; providing assistance to critical infrastructure in conducting timely cyber threat audits and analysis in preventing and detecting cyber attacks against them; ii) enhancing incident response capability to major cyber security incidents or massive cyber attacks; iii) strengthening thematic researches on cyber crime trend and mode of operation, vulnerabilities of computer systems and development of malware; iv) strengthening partnership with local stakeholders and overseas law enforcement agencies in information exchange and sharing of best practices to counter prevalent technology crime and cyber threats; and v) developing new training programmes on cyber security and technology crimes. hong kong's government recognizes the need to upgrade the police and equip them to face the ever-evolving technological landscape, with its ubiquitous mobile electronic devices such as smart mobile phones and tablets. furthermore, after being reintegrated with china for more than years, hong kong is far closer to china than ever before, economically and politically. the threat of terrorism from inside mainland china and especially from the xinjiang region has increased, and this terrorist group is known to be quite it savvy, often using social media to disseminate information and communicate with like-minded group members around the globe. they were said to have downloaded a video clip onto their smart mobile phones via the cloud and then watched it before carrying out their bombing attack inside mainland china. therefore, the hong kong government must consider this type of threat. the increase in muslim militant extremists represents an interregional, if not a global threat, and such militants are also known to use the electronic highway and smart mobile phones to carry out attacks and spreading ideological campaign material among themselves and other affiliated groups in asia. like hong kong, singapore is an important international financial center, yet its economy is more diverse, with a mixture of industries such as manufacturing, ibid., p. . oil refinery, shipping, and biotechnology. singapore is a democratic and a sovereign state with self-determination, even though its democratic process is regarded as a "controlled" democracy because the pap has been in power since the first day of independence from malaysia more than years ago, with little or no opposition in parliament. on august , , in a singapore national day speech broadcast live on channel news asia, prime minister lee hsien leong said, "keep singapore special in asia" by transforming it into "a smart nation." he introduced the singapore smart nation plan and provided detailed examples of a brand new housing community to be built in jurong lake district. the community will feature sensor boxes connected to fiber-optic lines deployed across the community and, eventually the entire country, at street lights, or bus stops. the sensor boxes can be designed to detect air pollutants, heavy rainfall, or traffic jams, or to report how full rubbish bins are, paired with cameras that can detect litter and remind litterbugs to pick up their trash. singapore has already laid the groundwork for the smart nation plan. for example, fiber internet is available to most households in the country, with super-fast gbps service costing as little as us$ per month. one of the key features of the proposed smart cities is the use of sensor boxes to set up wireless hotspots for a heterogeneous network, allowing smart phones and mobile devices to switch seamlessly between mobile data and wi-fi. singapore has also set aside spectrum to create new super wi-fi networks with greater range and coverage but a lower power requirement compared to standard wi-fi. the network will also be used to transmit smart nation data via the cloud. singapore is controlled from the top-down; it is an authoritarian society. the government is trying to harness the power of technology to increase the economy's productivity and efficiency. therefore, if the pap responds and wants to increase the resources provided to the singapore police to further increase their ability to fight the growing threat of technology-related crime, doing so will be relatively easier than it would be in many other democratic societies in western developed economies. singaporean voters may not necessarily agree with the pap's decisions regarding finite public resources being transferred from other more pressing social needs, as when they voted to form the government. however, the pap's manifesto may not mention anything about resources being earmarked for fighting technology-related crime, rather they may prefer to say that they will tackle traditional street crime and other forms of crime important to singaporean voters. even if both hong kong and singapore have the resources to respond to the potential risk of surging smart mobile phone crime, cloud computing-related crime is relatively new, and what worked in the past for less mobile devices such as personal computers may not work for the constant connectivity inherent in mobile devices. in the cloud, the configuration is usually a many-to-many network. to maximize the computing efficiency, virtualization is adopted, and thus data storage is located in host machine severs located in a many different places or countries. as gray explains: cloud technology offers wonderful potential for users in terms of convenience, ease of obtaining updates etc. however, it presents significant legal challenges. our laws, largely based on notions of territoriality, struggle to respond to technology in which lines on maps are largely irrelevant therefore, providing the financial resources is an important first step for law enforcement agencies to build up their policing capabilities in the cloud. other important elements are also required, such as knowledge of the cloud and the skills to find and collect electronic evidence in a live flow of data on a distribution network in the cloud, especially in a virtual machine. for example, in cloud data environments, it is often not possible to access the physical media that stores a customer's data, because cloud data are likely to be stored overseas and outside the investigating officer's jurisdiction. as hooper et al. noted: even if the data is stored within jurisdiction, data distribution technologies [in cloud] may split a user's data across a number (potentially thousands) of storage devices within the cloud computing environment. leas would need to rely upon the cloud technology and the cloud service provider to gain access to the data that is stored by a customer and this can introduce issues with chain-ofcustody best practices. another problem facing the investigating officer is the preservation of the cloud data evidence. the integrity of the data is important, so potential data evidence cannot be modified. however, when exporting cloud data evidence for examination by the investigating officer, there is a high chance of modification, as hooper et al. explain: preserved (to ensure that the potential evidence is not modified) function which many cloud computing environments do not currently support. consequently, this could result in accidental modification of data as it is exported from the cloud computing environment for lea [law enforcement agency] use or intentional destruction of data by the suspect. once the lea has secured access to the cloud computing data, the format of the data is still not guaranteed and most of the prevalent digital forensic analysis tools have not yet been updated to decode the major cloud computing data export formats. while many iaas data exports will likely mimic the data format that is currently supported as virtual machines, saas instances are more likely to use proprietary data formats and as such are unlikely to be supported by current tools finally, even if the police in singapore and hong kong do increase their policing capabilities in smart mobile phone and cloud-related crime, the legal limitations gray ( , p. ). see hooper et al. ( , p. ). ibid. remain a key factor in whether the perpetrator faces justice for the crime they have committed. even though singapore has enacted an extraterritorial law, because each country has enacted their own law according to their own socio-politic, socio-economic, cultural and legal traditions, and regulatory regimes, policing priorities differ by jurisdiction. there has been good progress on harmonizing the laws in recent years (interpol / mutual legal assistant, council of europe convention on cybercrime, etc.), but the task remains problematic due to jurisdictional issues. both hong kong and singapore will have trouble bringing an overseas perpetrator from their country of domicile to face justice for committing a cloud computing crime in hong kong or singapore. in short, it is clear from this chapter that lots of catching up need to be done for hong kong and singapore in order to beef-up their policing capability on cloud. at the domestic level, both governments in hong kong and in singapore must provide sufficient financial support to the policing agencies to enable them to fight the emerging crime such as cloud and smart mobile phone crimes. fighting technology-related crimes is an "arms race" which needs both money and human resources. more importantly, the government must provide training opportunities and education (including general public education to increase public awareness on emerging technologies crimes like cloud and smart mobile phone crimes and learning to cooperate with the private sector or businesses to reduce crime) for the law enforcement officers to upgrade their skills and knowledge on cloud which eventually help increase the success rate in bringing the perpetrator to face justice and punish them in court-as a deterrent to others not to commit the same offense. however, at the international level, it seems there is little that hong kong and singapore can do to alter the current situation, except to participate actively within the international bodies and convention on technology-related crime, and to learn from other jurisdictions around the world on what they are doing and, at the same time, tap into latest information on cloud computing crime to get a head start in fighting the emerging technology-related crime for themselves in the region. gmail smartphone app hacked by researchers eyes on the prize: law and economic development in singapore the development of criminal law and criminal justice cloud computing and its implications for cybercrime investigations in australia cloud computing for small business: criminal and security threats and prevention measures cyber crime-a growing challenge for governments legislative council panel on security creation of a permanent chief superintendent of police post of the cyber security and technology crime bureau technological policy and national competitiveness what went wrong for the pap in lockup or lose it, residents warned. south china morning post newspaper united nation international telecommunication union report information service department, hong kong sar government midnight world cup favours illegal bookmakers drawing new blood singapore: wealth, power and the culture of control key: cord- -kenstpja authors: nan title: china date: journal: the statesman&#x ;s yearbook doi: . / - - - - _ sha: doc_id: cord_uid: kenstpja nan yuan dynasty in , swept into southern china. the mongol yuan dynasty adopted chinese ways but was overthrown by a nationalist uprising in , led by hongwu ( - ), a former beggar who established the ming dynasty. the ming empire collapsed in a peasants' revolt in . the capital, beijing (peking), was only km from the great wall and vulnerable to attack from the north. within months the peasants' leader was swept aside by the manchus, whose qing dynasty ruled china until . preoccupied with threats from the north, china neglected its southern coastal frontier. the portuguese, who landed on the chinese coast in , were followed by the dutch in and the english in . the qing empire expanded into mongolia, tibet, vietnam and kazakhstan. but by the th century, under pressure from rural revolts ignited by crippling taxation and poverty, the qing dynasty was crumbling. two opium wars ( - ; - ) forced china to allow the import of opium from india into china, while britain, france, germany and other european states gained concessions in 'treaty ports' that virtually came under foreign rule. the taiping rebellion ( - ) set up a revolutionary egalitarian state in southern china. the european powers intervened to crush the rebellion and in british and french forces invaded beijing and burnt the imperial palace. further trading concessions were demanded. a weakened china was defeated by japan in and lost both taiwan and korea. the xenophobic boxer rebellion, led by a secret society called the fists of righteous harmony, broke out in . the guangxu emperor attempted modernization in the hundred days reform, but was taken captive by the conservative dowager empress cixi who harnessed the boxer rebellion to her own ends. the rebellion was put down by european troops in . china was then divided into zones of influence between the major european states and japan. with imperial authority weakened, much of the country was ripe for rebellion. in the kuomintang (guomintang or nationalist movement) of sun yet-sen (sun zhong shan; - ) overthrew the imperial system. the authoritarian yuan shih-kai ruled as president from to . following the overthrow of yuan, china disintegrated into warlord anarchy. in sun founded a republic in southern china but the north remained beyond his control. reorganizing the nationalist party on soviet lines, sun co-operated with the communists to re-establish national unity. but rivalry between the two parties increased, particularly after the death of sun in . after sun's death the nationalist movement was taken over by his ally chiang kai-shek (jiang jie shi; - . as commander in chief of the nationalist army from , chiang's power grew. in april his campaign to suppress the chinese communist party saw thousands of communists slaughtered. the survivors fled to the far western province of jiangxi. in chiang's army entered beijing. with the greater part of the country under chiang's rule, he made nanjing the capital. in the communists were forced to retreat from jiangxi province. led by mao zedong (mao tse-tung; - they trekked for more than a year on the , -mile long march, eventually taking refuge in shaanxi province. in the japanese invaded manchuria. by they had seized beijing and most of coastal china. the nationalists and communists finally co-operated against the invader but struggled against the superior japanese forces. during the second world war , a nationalist government ruled unoccupied china ineffectually from a temporary capital in chongqing. at the end of the war, nationalist-communist co-operation was short-lived. the soviet union sponsored the communist party, which marched into manchuria in , beginning a civil war that lasted until . although the nationalist forces of chiang kai-shek received support from some western countries, particularly the united states, the communists were victorious. on oct. mao declared the people's republic of china in beijing. chiang fled with the remains of his nationalist forces to taiwan, where he established a government that claimed to be a continuation of the republic of china. at first recognized as the government of china by most western countries, taiwan kept china's security council seat at the united nations until . chiang's authoritarian regime was periodically challenged by red china, which bombed taiwan's small offshore islands near the mainland. in the s and s, taiwan gradually lost recognition as the legitimate government and in the usa recognized the people's republic of china. in china invaded tibet, independent since . chinese rule quickly alienated the tibetans who rebelled in . the tibetan religious leader, the dalai lama, was forced to flee to india. since then, the settlement of large numbers of ethnic chinese in the main cities of tibet has threatened to swamp tibetan culture. during the s and s china was involved in a number of border disputes and wars in neighbouring states. the communists posted 'volunteers' to fight alongside communist north korea during the korean war . there were clashes on the soviet border in the s and the indian border in the s, when china occupied some indian territory. from the establishment of the people's republic of china, communist china and the soviet union were allies. communist china initially depended upon soviet assistance for economic development. a soviet-style five-year plan was put into action in , but the relationship with moscow was already showing signs of strain. by the end of the s the soviet union and china were rivals, spurring the chinese arms race. chinese research into atomic weapons culminated in the testing of the first chinese atomic bomb in . mao introduced rapid collectivization of farms in . the plan was not met with universal approval in the communist party but its implementation demonstrated mao's authority over the fortunes of the nation. in he launched the doctrine of letting a 'hundred flowers bloom', encouraging intellectual debate. however, the new freedoms took a turn mao did not expect and led to the questioning of the role of the party. strict controls were reimposed and free-thinkers were sent to work in the countryside to be 're-educated'. in may mao launched another ill-fated policy, the great leap forward. to promote rapid industrialization and socialism, the collectives were reorganized into larger units. neither the resources nor trained personnel were available for this huge task. backyard blast furnaces were set up to increase production of iron and steel. the great leap forward was a disaster. it is believed that m. died from famine. soviet advice against the project was ignored and a breakdown in relations with moscow came in , when soviet assistance was withdrawn. a rapprochement with the united states was achieved in the early s. having published his 'thoughts' in the 'little red book' in , mao set the cultural revolution in motion. militant students were organized into groups of red guards to attack the party hierarchy. anyone perceived to lack enthusiasm for mao zedong thought was denounced. thousands died as the students lost control and the army was eventually called in to restore order. after mao's death in the gang of four, led by mao's widow jiang qing, attempted to seize power. these hard-liners were denounced and arrested. china effectively came under the control of deng xiaoping. deng pursued economic reform. the country was opened to western investment. special economic zones and 'open cities' were designated and private enterprise gradually returned. improved standards of living and a thriving economy increased expectations for civil liberties. the demand for political change climaxed in demonstrations by workers and students in april , following the funeral of communist party leader hu yaobang. in beijing where demonstrators peacefully occupied tiananmen square, they were evicted by the military who opened fire, killing more than , . hard-liners took control of the government, and martial law was imposed from may to jan. . since the leadership has concentrated on economic development. hong kong was returned to china from british rule in (for the background, see page ) and macao from portuguese rule in . the late s saw a cautious extension of civil liberties but chinese citizens are still denied most basic political rights. beijing was chosen for the olympic games. china's treatment of tibet came under the international spotlight in the build-up to the games, following violent protests in tibet's capital city, lhasa. the arrest by japan of a chinese trawler in disputed waters in marked the beginning of heightened tensions between the two nations in the east and south china seas. in china became the world's second largest national economy. in nov. the communist party congress selected xi jinping to succeed hu jintao as president from march . in sept. that year, former leadership hopeful bo xilai received a life sentence for corruption in one of china's highest-profile trials in decades. in oct. the government announced the end of the country's one-child policy. a month later, the presidents of china and taiwan met for talks-the first time that leaders from the respective territories had met since . on the economic front, gdp growth in was at its lowest level for a quarter of a century. china is bounded in the north by russia and mongolia; east by north korea, the yellow sea and the east china sea, with hong kong and macao as enclaves on the southeast coast; south by vietnam, laos, myanmar, india, bhutan and nepal; west by india, pakistan, afghanistan, tajikistan, kyrgyzstan and kazakhstan. the total area (including taiwan, hong kong and macao) is estimated at , , sq. km ( , , sq. miles). a law of feb. claimed the spratly, paracel and diaoyutasi islands. an agreement of sept. at prime ministerial level settled sino-indian border disputes which had first emerged in the war of . china's sixth national census was held on nov. . the total population of the provinces, autonomous regions and municipalities and of servicemen on the mainland was , , , ( , , females, representing · %); density, per sq. km. china's population in represented % of the world's total population. the population rose by , , (or · %) since the census in . there were , , urban residents, accounting for · % of the population; compared to the census, the proportion of urban residents rose by · % (reflecting the increasing migration from the countryside to towns and cities since the economy was opened up in the late s). population estimate, dec. : , , , . china has a fast-growing ageing population. whereas in only · % of the population was aged or over and by this had increased to · %, by it is expected to rise to · %. long-term projections suggest that in as much as · % of the population will be or older. the population is expected to peak at · m. around and then begin to decline to such an extent that by around it will be back to the level. china is set to lose its status as the world's most populous country to india in about . the un gives a projected population for of , · m. regulations restricting married couples to a single child, a policy enforced by compulsory abortions and economic sanctions, were widely ignored, and it was admitted in that the population target of , m. by would have to be revised to , m. from peasant couples were permitted a second child after four years if the first born was a girl, a measure to combat infanticide. in china started to implement a more widespread gradual relaxation of the one-child policy. in dec. the standing committee of the national people's congress (npc) approved a resolution allowing couples to have two children if either parent was an only child. the one-child policy was formally abandoned altogether from jan. . an estimated m. persons of chinese origin lived abroad in . a number of widely divergent varieties of chinese are spoken. the official 'modern standard chinese' is based on the dialect of north china. mandarin in one form or another is spoken by m. people in china, or around % of the population of mainland china. the wu language and its dialects has some m. native speakers and cantonese m. around m. people in china cannot speak mandarin. the ideographic writing system of 'characters' is uniform throughout the country, and has undergone systematic simplification. in a phonetic alphabet (pinyin) was devised to transcribe the characters, and in this was officially adopted for use in all texts in the roman alphabet. the previous transcription scheme (wade) is still used in taiwan and hong kong. mainland china is administratively divided into provinces, five autonomous regions (originally entirely or largely inhabited by ethnic minorities, though in some regions now outnumbered by han immigrants) and four government-controlled municipalities. these are in turn divided into prefectures, cities (of which are at prefecture level and at county level), , counties and urban districts. tianjin, · m.; dongguan, · m.; wuhan, · m.; foshan, · m.; chengdu, · m.; chongqing, · m.; nanjing, · m.; shenyang, · m.; xian, · m.; hangzhou, · m.; haerbin, · m.; suzhou, · m.; dalian, · m.; zhengzhou, · m.; shantou, · m.; jinan, · m.; qingdao, · m.; changchun, · m.; kunming, · m.; changsha, · m.; taiyuan, · m.; xiamen, · m.; hefei, · m.; urumqi (wulumuqi), · m.; fuzhou, · m.; shijiazhuang, · m.; wuxi, · m.; zhongshan, · m.; wenzhou, · m.; nanning, · m.; ningbo, · m.; guiyang, · m.; lanzhou, · m.; zibo, · m.; changzhou, · m.; nanchang, · m.; xuzhou, · m about % of the population is engaged in the dominant industries of farming and animal husbandry. in the total sown area was , ha. output in : total grain crops, , tonnes; vegetables, , tonnes. in there were · m. sheep and goats and · m. cattle and yaks. tibet has over , mineral ore fields. mining, particularly of copper and gold, has expanded rapidly since when the railway came to tibet. cement production, : · m. tonnes. electricity consumption totalled · bn. kwh in . in there were , km of roads ( , km in ) . there are airports at lhasa, bangda and nyingchi providing external links. in , , foreign tourists visited tibet. in july a , -km railway linking lhasa with the town of golmud opened. it is the highest railway in the world. direct services have subsequently been introduced between lhasa and a number of major chinese cities, including beijing and shanghai. an extension from lhasa to shigatse, tibet's second largest city, became operational in aug. . in tibet had primary schools (with , pupils) and secondary schools of which were senior secondary schools (with , pupils), junior secondary schools (with , pupils) and eight whole secondary schools. there were also six vocational secondary schools in ( , pupils). tibet has six higher education institutes (the largest of which is tibet university), with , enrolled students in total in . the illiteracy rate of people aged and above was · % in . in there were , medical personnel (including , doctors) and , medical institutions, with a total of , beds. births, , , , ; deaths, , , . birth rate (per , population), · ; death rate, · . in the birth rate rose for the first time since . there were , , marriages and , , divorces in . in the marriage rate was · per , population and the divorce rate a record high · per , . the divorce rate has doubled since . in april parliament passed revisions to the marriage law prohibiting bigamy and cohabitation outside marriage. the suicide rate in china in was · per , population. life expectancy at birth, , was · years for men and · years for women. infant mortality, , per , live births. china has made some of the best progress in recent years in reducing child mortality. the number of deaths per , live births among children under five was reduced from in to in . fertility rate, , · births per woman (compared to over in the mid- s). annual population growth rate, - , · %. according to the world bank, the number of people living in poverty (less than us$ · a day) at purchasing power parity declined from m. in to m. in . most of china has a temperate climate but, with such a large country, extending far inland and embracing a wide range of latitude as well as containing large areas at high altitude, many parts experience extremes of climate, especially in winter. most rain falls during the summer, from may to sept., though amounts decrease inland. monthly average temperatures and annual rainfall ( ): beijing (peking), jan. · °f (- · °c), july · °f ( · °c). annual rainfall · " ( mm). chongqing, jan. · °f ( · °c), july · °f ( · °c). annual rainfall · " ( , mm). shanghai, jan. · °f ( · °c), july · °f ( · °c). annual rainfall · " ( , mm). tianjin, jan. · °f (- · °c), july · °f ( · °c). annual rainfall · " ( mm). on sept. the chinese people's political consultative conference met in beijing, convened by the chinese communist party. the conference adopted a 'common programme' of articles and the 'organic law of the central people's government' ( articles). both became the basis of the constitution adopted on sept. by the st national people's congress, the supreme legislative body. the consultative conference continued to exist after as an advisory body. three further constitutions have been promulgated under communist rule-in communist rule-in , communist rule-in and . the latter was partially amended in , , and , endorsing the principles of a socialist market economy and of private ownership. the unicameral national people's congress is the highest organ of state power. usually meeting for one session a year, it can amend the constitution and nominally elects and has power to remove from office the highest officers of state. there are a maximum of , members of the congress, who are elected to serve five-year terms by municipal, regional and provincial people's congresses. , xi pursued a strong style of authoritarian rule at home and a proactive and muscular foreign policy in his first term. in oct. the ccp gave him the title of 'core' leader, a significant honorific bracketing him with mao zedong and deng xiaoping among previous party figures although conferring no absolute powers. then, at its five-yearly congress in oct. , the party voted to enshrine his name and ideology in the chinese state constitution. he was subsequently re-elected in march and parliament also voted to abolish presidential term limits in a major shift from precedent. xi jinping was born on june in beijing, the son of one of the first generation of communist leaders. he joined the ccp in and, after graduating from tsinghua university in with a degree in chemical engineering, he became secretary to the vice-premier and secretary-general of the central military commission. xi became the zhengding county committee deputy secretary in hebei province in and the following year was promoted to secretary. in he was made deputy mayor of xiamen city, fujian province. having undertaken various party roles in the province, he became deputy governor of fujian in and governor a year later. in he moved to zhejiang province and made his first inroads into national politics when he was named a member of the th central committee. from - he was party secretary of fujian, overseeing economic growth averaging % a year and earning a reputation as an opponent of corruption. in march xi transferred to shanghai to take the role of party secretary following the dismissal of the incumbent on corruption charges. his appointment to such an important regional post was seen as a vote of confidence from the central government and he became a member of the politburo standing committee at the th party congress in oct. . he was also made a high-ranking member of the central secretariat. on march he was elected vice-president at the th national people's congress and took on a number of high profile portfolios including the presidency of the central party school. he was also beijing's senior representative for hong kong and ahead of his presidency, xi said little about his policy ambitions. there was hope abroad and at home that he would champion political and social reform and attempt to deal with corruption and a widening wealth gap between rich and poor and between urban and rural communities. he also faced the conundrum of how to provide adequate healthcare to a rapidly ageing population. in jan. the prospect of greater transparency and accountability under his leadership was undermined when the authorities began criminal proceedings against anti-corruption campaigners calling for public disclosure of officials' assets. this coincided with a report by a us investigative organization claiming that relatives of some of china's top political and military figures, including xi's brother-in-law, held secret offshore financial holdings. in other social and political affairs the ccp announced plans in nov. to ease china's one-child policy (which was subsequently abandoned following an announcement in oct. , with effect from ) and to abolish the system of 'reeducation through labour' camps, while a party plenum calledfor the first time-for markets to play a 'decisive' role in the allocation of resources. meanwhile, in xi was confronted by domestic political opposition in the form of militant attacks by ethnic uighur separatists from xinjiang region and, from sept. that year, by widespread pro-democracy and autonomy protests in hong kong. on the economic front, china's previously frenetic annual rate of growth slowed markedly in , reflecting a slump in factory production and concerns over depressed oil prices, and again in to its lowest since . it also heralded severe stock market turbulence into despite emergency government measures, which had negative reverberations throughout the world economy. nevertheless, recognizing china's rise as a global economic power, the imf in nov. voted to add the yuan as the fifth member of its special drawing rights (sdr) currency basket alongside the us dollar, japanese yen, british pound and the euro. in foreign affairs, regional concerns over china's territorial and military intentions were raised in nov. by the government's declaration of a new 'air defence identification zone' over a swathe of the east china sea including disputed islands claimed by japan and south korea. there has also been friction, regionally and with the usa, over china's sovereignty claims and land reclamation operations on islands in the south china sea, although in july an international legal tribunal ruled in favour of a challenge by the philippines to china's sovereignty assertions-a verdict beijing vowed to ignore. further afield, xi has meanwhile undertaken numerous official visits abroad, as well as attending multilateral forums, for diplomatic, trading and investment purposes. and, while in singapore in nov. , xi and president ma ying-jeou of taiwan held the first direct talks between leaders of the two estranged governments since their split in . most recently, xi urged greater trade co-operation with the usa during his first encounter with the new us president, donald trump, in april , while also increasing economic and military cooperation with russia. li keqiang took office as premier of the state council, a role equivalent to prime minister, in march , succeeding wen jiabao. he was re-elected in march . li keqiang was born on july in dingyuan county, anhui province. following graduation from high school in , he joined the ccp and in he graduated in law from peking university, serving as head of the students' federation from - . he went on to earn a master's degree and doctorate in economics and headed the university's communist youth league of china (cylc) committee. over the following two decades he rose through the cylc ranks, joining the secretariat of its central committee in the s and serving as its first secretary in the s. at this time he built up his power base and forged close ties with hu jintao, a fellow cylc committee member and future chinese president. in li became deputy party secretary for henan province and a year later was appointed henan's governor. in dec. he was named party secretary for liaoning province where he spearheaded a major coastal infrastructure project, the ' points and one line' highway development. in this template was adopted at the national level to rejuvenate industrial northeast china. he also oversaw the rehousing of · m. shanty-town residents into new apartment blocks over a three-year period. li advanced to national level politics when he was elected to the politburo standing committee in oct. . he was appointed vice-premier of the state council in march , leading a medical reform programme aimed at creating an accessible public healthcare service. he also chaired an affordable housing programme and introduced tax reform plans. in nov. li was re-elected as a member of the politburo standing committee and on march became premier of the state council at the th national people's congress. regarded as the steward of the chinese economy, li was expected to focus on securing china's long-term expansion and on the further provision of basic national healthcare, affordable housing, employment growth, regional development and cleaner energy. however, global confidence in china's economy has been shaken since as the country's growth momentum has slowed amid apparent policy differences and blunders, prompting rumours that li was being increasingly sidelined in the governing hierarchy. he was nevertheless re-elected to the politburo standing committee in oct. and to the premiership in march . the chinese president is chairman of the state and party's military commissions. china is divided into seven military regions. the military commander also commands the air, naval and civilian militia forces assigned to each region. china's armed forces (pla: 'people's liberation army'), totalling nearly · m. in including the paramilitary people's armed police (pap) and · m. excluding the pap, are the largest of any country. however, active armed personnel numbers have halved since . moreover, in president xi laid out plans to reform the army structure-replacing an organization based on seven regions with one based on five 'theatre commands'-and reduce the number of military personnel by a further , . conscription is compulsory, but for organizational reasons, is selective: only some % of potential recruits are called up. service is for two years. a military academy to train senior officers in modern warfare was established in . defence expenditure in was us$ , m. (equivalent to us$ per capita). china's military spending more than trebled during the s. defence spending in represented · % of gdp. only the usa spent more on defence in , but china's defence expenditure totalled around a fifth of that of the usa. in march it was announced that the defence budget would rise by · % to us$ bn. following increases of · %, · % and · % in the previous three years. china is the world's third largest exporter of arms after the usa and russia, with · % of the global major weapons total over the period - . in the period - it had only been the eighth largest exporter. as at may china had , personnel serving in un peacekeeping operations (the largest contingent of any of the five permanent members of the un security council and more than the other four combined). having carried out its first test in , there have been tests in all at lop nur, in xinjiang (the last in ). the nuclear arsenal consisted of approximately operational warheads in jan. according to the stockholm international peace research institute. china has been helping pakistan with its nuclear efforts. the army (pla: 'people's liberation army') is divided into main and local forces. main forces, administered by the seven military regions in which they are stationed, but commanded by the ministry of defence, are available for operation anywhere and are better equipped. local forces concentrate on the defence of their own regions. ground forces are divided into infantry, armour, artillery, air defence, aviation, engineering, chemical defence and communications service arms. there are also specialized units for electronic counter-measures, reconnaissance and mapping. in there were group armies covering seven military regions. they included: armoured divisions and brigades; mechanized infantry divisions, brigades and regiments; motorized infantry divisions and brigades; nine special operations units; artillery divisions and brigades; amphibious brigades and divisions; two mountain brigades; aviation brigades and regiments; and two guard divisions. total strength in was · m. including some , conscripts. reserve forces are undergoing major reorganization on a provincial basis but are estimated to number some , . there is a paramilitary people's armed police force estimated at , under pla command. in nov. the naval arm of the pla included submarines, of which three were strategic (two jin-class and one xia-class) and tactical. by mid- two more jin-class nuclear-powered ballistic missile submarines had entered service. surface combatant forces in nov. included destroyers and frigates. sea trials of china's first aircraft carrier, liaoning (a former soviet warship purchased from ukraine), began in aug. . it entered service in sept. and was initially only used for training before being declared 'combat ready' in nov. . work on china's first domestically-built aircraft carrier began in . it was launched in april and is expected to be operational by . there is a land-based naval air force of about combatcapable aircraft, primarily for defensive and anti-submarine service. the force includes h- strategic bombers and jh- fighters. the naval arm is split into a north sea fleet, an east sea fleet and a south sea fleet. in naval personnel were estimated at , , including , in the naval air force and , conscripts. the people's liberation army air force organizes its command through seven military region air forces. the air force has an estimated , combat-capable aircraft. equipment includes j- (mig- ) interceptors (known in the west as 'fishbed'), h- chinese-built copies of tu- strategic bombers, q- fighterbombers (evolved from the mig- and known in the west as 'fantan'), su- fighters supplied by russia (known in the west as 'flanker'), j- chinese-designed and produced fighters (known in the west as 'firebird') and j- locally-developed fighters (known in the west as 'finback'). total strength ( ) was , . in agriculture accounted for · % of gdp, industry · % and services · %. industry was the largest contributor until , while services only overtook agriculture as the second largest sector in . in the late s agriculture was the largest contributor towards gdp. china's economic performance has been marked by high rates of growth for over three decades. annual gdp increases in the early s consistently exceeded % until the global financial crisis. china also holds the world's largest foreign exchange reserves, at more than us$ · trn. in april , although they have been falling since as the central bank strives to boost the currency in the face of large capital outflows. it is among the top recipients of foreign direct investment (fdi) and is the world's largest producer and consumer of coal. in china made the transition from net receiver of foreign aid to net donor and has established itself as a key player in africa's economic development, becoming the largest export partner of sub-saharan africa in . according to the world bank, china's cumulative fdi stock in africa totalled nearly us$ · bn. in , up from us$ · bn. in . in china overtook japan to become the world's second largest economy after the usa. the first steps from a centrally-planned towards a more market-oriented economy were taken by deng xiaoping in the late s. he opened the economy to foreign trade and investment, decentralized industrial management and allowed private sector development. in china became a member of the world trade organization, establishing trade relations with many countries. private entrepreneurs and foreign investors have played an important role in developing the manufacturing sector, china's principal growth engine. even before the economy was heavily skewed towards manufacturing, but following the market-oriented transition output increased significantly. during this period there was a structural shift away from large state-owned enterprises (soes), although these still remain an important part of the economy. between and the government oversaw reform of soes, with many poorly performing businesses privatized or liquidated. stronger firms were restructured and often listed on the stock market. many more recent enterprises are labourintensive as distinct from the capital-intensive soes. growth has been fuelled by low added value and labour-intensive exports. however, chinese firms are predicted to become increasingly competitive with higher added value producers, such as south korea. although the global financial crisis reduced the rate of growth and inbound fdi, china's recovery was among the earliest. gdp growth averaged · % in the second quarter of , up from a two-decade low of · % in the first quarter of that year. fdi also recovered rapidly, averaging · % of gdp annually between and . growth was rooted in a stimulus package of trn. yuan (us$ bn. or % of gdp), including fiscal spending and interest rate cuts, as well as an expansionary monetary policy. central government committed · trn. yuan, with the rest coming from local government, banks and soes. although exports declined by around % in , other countries fared worse and china's share of world exports increased to nearly · % in (up from % in ), making it the world's largest merchandise provider. gdp growth in stood at more than % but moderated between and , reflecting the global economic slowdown and diminishing dividends from past reforms. in aug. a devaluation of the yuan sent the shanghai stock exchange plummeting by nearly %, which was swiftly followed by a surge in capital outflows. the stock market meltdown lasted until feb. , with trading halted altogether for two days in jan. that year. nonetheless, the shanghai exchange subsequently began a recovery and had stabilized (at around , points) by feb. . despite stock market turbulence, the property market, which constitutes a quarter of china's gdp and is vital to the banking sector (as it accounts for a substantial amount of its collateral), remained buoyant. gdp growth declined to · % in (the slowest rate in years) and fell again to · % in as china attempted to reduce its reliance on exports, increase domestic consumption and develop its service sector. the economy then grew by · % in . rapid economic advance has brought with it a number of challenges that threaten future growth. notably, china's cost advantage has been undermined in recent years by rising wages and transportation costs, as well as weak global demand. other concerns include rising property costs, high levels of local government debt, lack of enforcement of intellectual property rights, endemic corruption at government level and credit and investment dependence, while total social financing-a broad measure of total credit-increased by % of gdp between and early . the stimulus package implemented by the government to boost growth increased total debt levels to more than double the value of gdp in . according to the imf, an increase in consumer demand and a reduced dependence on exports and investment are keys to achieving stable long-term economic expansion. china's th five-year plan (covering - ) aims to promote domestic consumption and to support innovation and entrepreneurship within a framework of balanced and sustainable development. efforts to promote domestic consumption have seen exports' share of gdp falling from % in to · % in and a lower investment contribution to gdp. the continued decline in commodity prices coupled with china's economic slowdown has had knock-on effects for commodityexporting nations, such as brazil, indonesia and argentina, given that china consumes about half of the world's steel, aluminium and nickel. inefficient production and outmoded equipment have meanwhile led to significant environmental problems, especially in the north of the country. air pollution, soil erosion and a declining water table are of particular concern. china has become the world's largest consumer of coal and second largest consumer of oil after the usa. the government aims to diversify its energy sources, relying less on coal and more on nuclear and alternative energy sources. there has been heavy investment in hydro-power, including the three gorges dam. since , m. people have been lifted out of poverty, yet china still has the second largest number of poor in the world after india. the world bank estimates that · m. people lived below the national poverty line at the end of (equivalent to income less than us$ per day), located mainly in remote and resource-poor regions and particularly in the west and the interior. nonetheless, some progress has been made, with · % of the rural population living below the poverty line in compared to · % in . growing inequality between urban and rural regions, particularly in terms of educational opportunities, needs to be addressed, however. china also faces the growing burden of an ageing population. those aged and over accounted for · % of the total population in , up from · % in . the currency is called renminbi (i.e. people's currency). the unit of currency is the yuan (cny) which is divided into ten jiao, the jiao being divided into ten fen. the yuan was floated to reflect market forces on jan. while remaining state-controlled. for years the people's bank of china maintained the yuan at about · to the us dollar, allowing it to fluctuate but only by a fraction of % in closely supervised trading. in july it was revalued and pegged against a 'market basket' of currencies the central parities of which were determined every night. in july , after three years of sharp appreciation, it was repegged at around · yuan to the dollar, leading to claims from some international observers that it was being kept unfairly low to boost exports. in june the government announced that the yuan would be allowed to move freely against the dollar as long as a rise or fall does not exceed · % within a single day. in aug. the yuan was devalued by a total of · % on three consecutive days. in aug. total money supply was , · bn. yuan, gold reserves were · m. troy oz and foreign exchange reserves us$ , · bn. (us$ · bn. in of the total revenues in central government accounted for , · bn. yuan and local governments , · bn. yuan. tax revenues came to , · bn. yuan in (including domestic vat , · bn. yuan and corporate income tax , · bn. yuan) and non-tax revenues , · bn. yuan. of the total expenditure in central government accounted for , · bn. yuan and local governments , · bn. yuan. the leading items of expenditure in were education ( , · bn. yuan) and social safety net and employment effort ( , · bn. yuan). the standard rate of vat is %. savings deposits in various forms in all banking institutions totalled , · bn. yuan in ; loans amounted to , · bn. yuan. there are stock exchanges in the shenzhen special economic zone and in shanghai. a securities trading system linking six cities (securities automated quotations system) was inaugurated in for trading in government bonds. china received a record us$ · bn. worth of foreign direct investment in , up from us$ · bn. in . external debt totalled us$ , m. in (up from us$ , m. in ) and represented · % of gni. china's carbon dioxide emissions from the consumption and flaring of fossil fuels in accounted for · % of the world total (making it the biggest emissions producer, having overtaken the usa in ) and were equivalent to · tonnes per capita (up from · tonnes per capita in ). an environmental performance index compiled in ranked china th of countries, with · %. the index examined various factors in nine areas-agriculture, air quality, biodiversity and habitat, climate and energy, fisheries, forests, health impacts, water and sanitation, and water resources. pollution is estimated to cost china about % of gdp annually. installed generating capacity in was an estimated , m. kw, compared with m. kw in . in electricity output was , , gwh, up from , , gwh in . consumption per capita was , kwh in . rapidly increasing demand has meant that more than half of china's provinces have had to ration power. sources of electricity in as percentage of total production: thermal, · %; hydro-electric power, · %; wind. · % (china is one of the world's largest producers of wind power); and nuclear, · %. in there were nuclear reactors in use and under construction. generating electricity is not centralized; local units range between and mw of output. in dec. china formally broke up its state power monopoly, creating instead five generating and two transmission firms. the three gorges dam project on the yangtze river was launched in and is intended to produce abundant hydro-electricity (as well as helping flood control). the first three , -kw generators in service at the project's hydro-power station began commercial operation in july . the original specification was completed in oct. , although six more generators have been added in the meantime (bringing the total to ). the final two generators become operational in july , giving the dam an overall capacity of · gw. china surpassed germany in terms of solar generating capacity in , with · gw at the end of the year. on-shore oil reserves are found mainly in the northeast (particularly the daqing and liaohe fields) and northwest. there are off-shore fields in the continental shelves of east china. oil production was a record · m. tonnes in . china is the second largest consumer of oil after the usa. ever-growing demand has meant that increasing amounts of oil are having to be imported. a -km pipeline from skovorodino in russia to daqing in the northeast of china was inaugurated in jan. , allowing china to increase significantly its imports of oil from the world's second largest producer. the , -km turkmenistan-china gas pipeline, bringing natural gas to xinjiang in china via kazakhstan and uzbekistan, was inaugurated in dec. . this connects with china's second west-east gas pipeline. only the usa imports more oil. domestic production now accounts for only % of consumption, compared to nearly % in . proven reserves in were · bn. bbls. the largest natural gas reserves are located in the western and north-central regions. production was a record · bn. cu. metres in -up from · bn. cu. metres in -with proven reserves of · trn. cu. metres in . china is the second largest producer of wind power after the usa, with · bn. kwh in . in total installed capacity amounted to , mw, the highest of any country and · % of the world total. china is one of the world's leading mineral producing and consuming countries. recoverable deposits of coal in totalled · bn. tonnes, mainly distributed in north china (particularly shanxi province and the inner mongolia autonomous region). coal production was , m. tonnes in . annual coal production has increased every year since . growing domestic demand nonetheless meant that china became a net importer of coal in . iron ore reserves were · bn. tonnes in . deposits are abundant in the anthracite field of shanxi, in hebei and in shandong, and are found in conjunction with coal and worked in the northeast. production in was , m. tonnes, making china the world's largest iron ore producer. it is also the largest consumer, at around % of the global total in . tin ore is plentiful in yunnan, where the tin-mining industry has long existed. tin production was , tonnes in . china is a major producer of wolfram (tungsten ore). there is mining of wolfram in hunan, guangdong and yunnan. output of other minerals (in , tonnes) in : salt, , ; bauxite, , ; aluminium, , ; zinc, , ; lead, , ; copper, , . there are also reserves of diamond, nickel, barite, bismuth, graphite, gypsum, mercury, molybdenum, silver, salt, phosphate ore and sylvite. gold production, : tonnes. china surpassed south africa as the world's leading gold producer in , since when its output has increased every year. agriculture accounted for approximately % of gdp in , compared to over % in at the time of the birth of the people's republic of china and over % in . in sown areas for major crops were (in m. ha.): corn, · ; rice, · ; wheat, · ; soybeans, · ; tubers, · ; rapeseed, · . intensive agriculture and horticulture have been practised for millennia. present-day policy aims to avert the traditional threats from floods and droughts by soil conservancy, afforestation, irrigation and drainage projects, and to increase the 'high stable yields' areas by introducing fertilizers, pesticides and improved crops. in aug. more than m. ha., notably in the yangtze valley, were under water as china experienced its worst flooding since the s. the flood season claimed over , lives. 'township and village enterprises' in agriculture comprise enterprises previously run by the communes of the maoist era, cooperatives run by rural labourers and individual firms of a certain size. there were , state farms in with · m. employees. net per capita annual income of rural households, : , yuan. in there were an estimated · m. ha. of arable land and · m. ha. of permanent cropland; · m. ha. were equipped for irrigation. there were · m. large/medium-sized tractors in and · m. small tractors. china is the world's leading producer of a number of agricultural crops. production of major products (in m. , - . forestry in the area under forests was · m. ha., or % of the total land area. the average annual increase in forest cover of , , ha. between and was the highest of any country in the world. total roundwood production in was · m. cu. metres, making china the world's third largest timber producer ( · % of the world total in ). it is the highest consumer of roundwood; timber consumption in totalled · m. cu. metres. it is also the world's leading importer of roundwood, accounting for · % of world timber imports in . output of major products, unless otherwise indicated (in tonnes): cement, , · m.; rolled steel, , · m.; crude steel, · m.; pig iron, · m.; gas oil and diesel oil ( ), · m.; gasoline, · m.; paper and paperboard, · m.; sulphuric acid, · m.; chemical fertilizers, · m.; fuel oil ( ), · m.; yarn, · m.; refined sugar, · m. also produced in : cloth, , m. metres; beer, , · m. litres; , · m. mobile phones; · m. notebook pcs; · m. colour tv sets; · m. air conditioners; · m. home refrigerators; · m. washing machines; · m. bicycles; · m. cameras; · m. motorcycles. china is the world's leading cement, steel and pig iron manufacturer; since output of cement has doubled and production of crude steel and pig iron has quadrupled (although in both crude steel and pig iron production fell for the first time in years). china overtook japan as the world's largest producer of motor vehicles in , and in produced · m. cars and · m. commercial vehicles. the employed population at the census was · m. ( · m. female). by it had risen to · m. ( · m. more than in ), of whom · m. worked in rural areas ( · m. fewer than in ) and · m. in urban areas ( · m. more than in ). in china's registered urban jobless was · %, with · m. registered unemployed in the country's cities. with china's fast-growing ageing population, according to the united nations the working-age population began to decline in . in china had , private industrial enterprises. it was not until the late s that the private sector even came into existence in china. the average annual wage of people working in urban units in was , yuan. china's labour law stipulates a five-day working week with no more than eight hours a day and no more than hours a week. minimum working age was fixed at in . strikes over pay have become ever more frequent in china, particularly at foreign-owned facilities. china had · m. people living in slavery according to the walk free foundation's global slavery index, the second highest total of any country. there are five special economic zones at shenzhen, xiamen, zhuhai, shantou and hainan in which concessions are made to foreign businessmen. the pudong new area in shanghai is also designated a special development area. since joint ventures with foreign firms have been permitted. a law of april reduced taxation on joint ventures to %. there is no maximum limit on the foreign share of the holdings; the minimum limit is %. in china is the second largest trading nation in the world, accounting for · % of global merchandise imports by value in and · % of global merchandise exports (up from · % when it joined the wto in ). it was the second largest importer in behind the usa and the largest exporter. as recently as the usa's total trade in goods was more than twice that of china. it overtook germany as the largest exporter of goods in . its trade surplus in goods is the highest of any country. however, it has the world's highest trade deficit in services. in imports of services totalled us$ bn. but exports only us$ bn. main imports in (in us$ bn.): machinery and transport equipment, · ; non-edible raw materials, · ; mineral fuels, lubricants and related materials, · ; chemicals, · . major exports in (in us$ bn.): machinery and transport equipment, , · ; miscellaneous manufactured goods, · ; light textile industrial products, rubber products, minerals and metallurgical products, · ; chemicals, · . the main trading partners were as follows in (in us$ m.): the total road length in was , , km, including , km of expressways (of which there had not been any as recently as the mid- s); , m. tonnes of freight and , m. persons were transported by road that year. the number of civilian motor vehicles was · m. in , including · m. passenger vehicles and · m. trucks (more than double the number in , when there were · m. civilian vehicles overall including · m. passenger vehicles and · m. trucks). china is the world's fastest-growing car market. there were , traffic accidents in , with , fatalities. in in jan. there were , ships of gt or over registered, totalling · m. gt. of the , vessels registered, were bulk carriers, general cargo ships, oil tankers, container ships, passenger ships and liquid gas tankers. mainland china's busiest port in was ningbo-zhoushan (handling · m. tonnes of cargo), followed by shanghai ( · m. tonnes), tianjin ( · tonnes), guangzhou (canton) ( · m. tonnes) and qingdao ( · m. tonnes). shanghai overtook singapore to become the world's busiest container port in and handled · m. teus (twenty-foot equivalent units) in . shenzhen, mainland china's second busiest port for container traffic and the world's fourth busiest in , handled · m. teus. hong kong handled · m. teus in . in jan. the first legal direct shipping links between the chinese mainland and taiwanese islands in more than years were inaugurated. inland waterways totalled , km in ; , · m. tonnes of freight and · m. passengers were carried. in june the three gorges reservoir on the chang jiang river, the largest water control project in the world, reached sufficient depth to support the resumption of passenger and cargo shipping. out of countries analysed in the fragile states index-a list published jointly by the fund for peace and foreign policy magazine-china was ranked the th most vulnerable to conflict or collapse. the index is based on indicators of state vulnerability across social, political and economic categories. six new codes of law (including criminal and electoral) came into force in , to regularize the legal unorthodoxy of previous years. there is no provision for habeas corpus. as well as treason and murder the death penalty may be used for rape, embezzlement, smuggling, fraud, theft, drug-dealing, bribery and robbery with violence. amendments to the criminal law in and reduced the number of capital crimes-which include both violent and non-violent offences-from to and further to . china does not divulge figures on its use of the death penalty, but amnesty international reported that in china executed thousands of people and was the world's top executioner. nevertheless, western analysts believe that the number of executions now is around a fifth of the yearly total in the s. 'people's courts' are divided into some higher, intermediate and , basic-level courts, and headed by the supreme people's court. the latter, the highest state judicial organ, tries cases, hears appeals and supervises the people's courts. it is responsible to the national people's congress and its standing committee. people's courts are composed of a president, vice-presidents, judges and 'people's assessors' who are the equivalent of jurors. 'people's conciliation committees' are charged with settling minor disputes. there are also special military courts. procuratorial powers and functions are exercised by the supreme people's procuracy and local procuracies. in march the national people's congress passed legislation developing aspects of the general principles of civil law, with effect from oct. . among its provisions was the extension of legitimate rights and interests from chinese citizens only to anyone conducting civil activities in the country. in addition, the statute of limitation was increased from two to three years. the number of sentenced prisoners in mid- was , , ( per , of national population). china was ranked th of countries for criminal justice and th for civil justice in the world justice project rule of law index, which provides data on how the rule of law is experienced by the general public across eight categories. an educational reform of brought in compulsory nine-year education consisting of six years of primary schooling and three years of secondary schooling, to replace a previous five-year system. in mainland china the population census revealed the following levels of educational attainment: · m. people had finished university education; · m. had received senior secondary education; · m. had received junior secondary education; and · m. had had primary education. · m. people over years of age or · % of the population were illiterate, although this compared favourably with a · % rate of illiteracy in the census and a · % rate in . in adult literacy was estimated at · %; youth literacy in was · %. in there were , kindergartens with · m. children and · m. full-time teachers; , regular primary schools with · m. pupils and · m. full-time teachers; , secondary schools (including: , senior secondary; , junior secondary; , specialized; , vocational; and , technical) with · m. pupils and · m. full-time teachers. there were also , pupils at , special education schools. institutes of higher education, including universities, numbered , in , with · m. undergraduates and · m. postgraduate level students, and · m. full-time teaching staff. china has more than private universities, almost all of which have been established since the mid- s. a national system of student loans was established in . the number of chinese students studying abroad went up from , in to , in ; it rose above , in and , in , and by exceeded , , making china the largest source of overseas students in the world. chinese students account for a fifth of all international students in tertiary education in the oecd, but fewer than half return to china after finishing their studies. the number of chinese undergraduate students in american universities in - was times as many as in - , rising from , to , in the space of seven years. there is an academy of sciences with provincial branches. an academy of social sciences was established in . in national government expenditure on education came to , , m. yuan and accounted for · % of national government spending. medical treatment is free only for certain groups of employees, but where costs are incurred they are partly borne by the patient's employing organization. in there were , health institutions throughout china, including , hospitals, , local health centres, , centres for disease control and prevention, and , specialized prevention and treatment centres. china's first aids case was reported in . at the end of there were , reported cases of people living with hiv/ aids. the number of deaths of people who had been living with hiv/aids in was , . in the first half of china was struck by an epidemic of a pneumonia-type virus identified as sars (severe acute respiratory syndrome). the virus was first detected in southern china and was subsequently reported in over other countries. according to the ministry of health, by the time the outbreak had been contained a total of , cases had been reported on the chinese mainland; , patients were cured and discharged from hospital, and died. in water: at what cost? the state of the world's water , wateraid reported that · % of the population does not have access to safe water. china ranked as the country with the second largest number of people living without access to safe water ( · m. in ). in an estimated · % of adult males and · % of adult females smoked in china. a study from the same year estimated that chinese males smoke one-third of all the world's cigarettes. in there were , social welfare enterprises with · m. beds. numbers (in , ) of beneficiaries of relief funds in : urban residents receiving minimum living allowance, , ; rural residents receiving minimum living allowance, , ; persons receiving traditional relief, ; persons in rural households entitled to the 'five guarantees' (food, clothing, medical care, housing and burial expenses), , . the official retirement age for men is and for women (or in the case of civil servants and professionals). the government accords legality to five religions only: buddhism, islam, protestantism, roman catholicism and taoism. confucianism, buddhism and taoism have long been practised. confucianism has no ecclesiastical organization and appears rather as a philosophy of ethics and government. taoism-of chinese origin-copied buddhist ceremonial soon after the arrival of buddhism two millennia ago. buddhism in return adopted many taoist beliefs and practices. a more tolerant attitude towards religion had emerged by , and the government's bureau of religious affairs (since renamed the state administration for religious affairs) was reactivated. ceremonies of reverence to ancestors have been observed by the whole population regardless of philosophical or religious beliefs. a new quasi-religious movement, falun gong, was founded in , but has since been banned by the authorities. the movement has claimed some m. adherents, although the chinese government has disputed this. muslims are found in every province of china, being most numerous in the ningxia-hui autonomous region, yunnan, shaanxi, gansu, hebei, henan, shandong, sichuan, xinjiang and shanxi. roman catholicism has had a footing in china for more than three centuries. two christian organizations-the chinese patriotic catholic association, which declared its independence from rome in , and the protestant three-self patriotic movement-are sanctioned by the chinese government. according to estimates (by the state-approved xinhua news agency, the chinese academy of social sciences and the state administration for religious affairs) there were m. buddhists (more than in any other country), m. christians and more than m. muslims in the country in . other official figures indicate that there are · m. catholics, although unofficial estimates are much higher. the number of christians in china is generally thought to be far higher than official numbers indicate, with socalled 'house churches' becoming ever more popular. some analysts estimate that there are as many as m. christians overall. legislation of prohibits foreign nationals from setting up religious organizations. in , , m. volumes of books were produced. in tourist numbers totalled · m. the world tourism organization predicts that china will overtake france as the world's most visited destination by . it was the third most visited destination in after france and the usa. income from tourists in was us$ · bn., ranking it fourth behind the usa, spain and france. expenditure by chinese travellers outside of mainland china for was us$ · bn., the most of any country. in both german and us travellers abroad had spent more than those from china. the lunar new year, also known as the 'spring festival', is a time of great excitement for the chinese people. constituencies encompassing all eligible persons in a workforce of · m., and ten from an election committee formed by members of district boards. a president was elected from and by the members. at the elections on sept. turnout for the geographical seats was · %, and for the functional seats ( of which were contested), · %. the democratic party and its allies gained seats, the liberal party and the pro-beijing democratic alliance . the remaining seats went to independents. on dec. the selection committee selected a provisional legislature which began its activities in jan. while the legislative council was still functioning. in jan. the provisional legislature started its work by enacting legislation which would be applicable to the hong kong special administrative region and compatible with the basic law. constitutionally hong kong is a special administrative region of the people's republic of china. the basic law enables hong kong to retain a high degree of autonomy. it provides that the legislative, judicial and administrative systems which were previously in operation are to remain in place. the special administrative region government is also empowered to decide on hong kong's monetary and economic policies independent of china. in july the first-past-the-post system of returning members from geographical constituencies to the legislative council was replaced by proportional representation. there were directly elected seats out of for the first elections to the legislative council following hong kong's return to chinese sovereignty, increasing in accordance with the basic law to for the election with indirectly elected. in the sept. legislative council election (and that of sept. ) of the seats were directly elected. for the election in sept. the number of seats was increased to , with directly elected and indirectly elected by functional constituencies. there were also five new functional constituency seats nominated by elected district council members. the chief executive is chosen by a beijing-backed , -member election committee ( prior to the march election), although it has been stated that universal suffrage is the ultimate aim. in a timetable was announced for hong kong to directly elect its chief executive in and its legislative council in . however, beijing insisted that only approved candidates would be allowed to stand in , prompting mass pro-democracy rallies in the territory in and formal rejection of the plan by the legislative council in june . beijing nevertheless refused to countenance amendments. in july a new accountability or 'ministerial' system was introduced, under which the chief executive nominates for appointment policy secretaries, who report directly to the chief executive. the chief executive is aided by the executive council, consisting of the three senior secretaries of department (the chief secretary, the financial secretary and the secretary for justice) and eleven other secretaries plus five non-officials. according to the anti-corruption organization transparency international, hong kong ranked equal th in the world in a survey of the countries and regions with the least corruption in business and government. it received out of in the annual index. overview hong kong has one of the world's most open economies and is an internationally important financial centre. the territory's economic rise was founded on its role as an international trade emporium, acting as a conduit for china's burgeoning exports. mainland china, the usa and japan are hong kong's major export partners, accounting for · %, · % and · % of exports respectively in . the island is dependent on imports of food and other resources. in it imported % of goods from mainland china, % from taiwan and % from japan. in and the economy grew strongly on the back of a rise in chinese tourism, healthy global demand for exports and improving domestic consumer confidence. however, the global financial crisis saw the economy shrink by · % in before rebounding with a · % increase the following year. between and annual growth averaged · %, supported by strong external demand. student-led pro-democracy protests in the latter months of caused major disruption in several key business districts and threatened to weaken the local economy in the short term. foreign direct investment levels have been high, averaging % of gdp between and according to world bank data, and the world economic forum ranked hong kong as the ninth most competitive economy in the world in its report. the government aims to tackle a housing shortage by providing , new housing units by the mid- s. the unit of currency is the hong kong dollar (hkd) of cents. it has been pegged since at a rate of hk$ · to the us dollar. banknotes are issued by the hongkong and shanghai banking corporation and the standard chartered bank, and, from may , the bank of china. total money supply was hk$ , m. in july . in aug. gold reserves were , troy oz and foreign exchange reserves were us$ , m. inflation rates (based on imf statistics): in - revenue totalled hk$ · bn. and expenditure hk$ · bn. earnings and profits taxes accounted for · % of revenues in - and indirect taxes · %; education accounted for · % of expenditures and social welfare · %. hong kong's carbon dioxide emissions from the consumption of energy in were the equivalent of · tonnes per capita. installed capacity was · m. kw in . production in was · bn. kwh. hong kong is a net importer of electricity. consumption in was · bn. kwh. the local agricultural industry is directed towards the production of high quality fresh food through intensive land use and modern farming techniques. out of the territory's total land area of , sq. km, only sq. km is currently farmed. in local production accounted for % of live poultry consumed, % of live pigs and % of fresh vegetables. the gross value of local agricultural production totalled hk$ , m. in , with pig production valued at hk$ m., poultry production (including eggs) at hk$ m., and vegetable and flower production at hk$ m. in the total catch was , tonnes, exclusively from marine waters. the leading companies by market capitalization in hong kong in may were: china mobile, a telecommunications company (us$ · bn.); aia group, a life insurance company (us$ · bn.); and cnooc, an integrated oil company (us$ · bn.). industry is mainly service-oriented. in june there were , establishments employing , , persons in service industries and , establishments employing , persons in manufacturing industries. establishment statistics by service type (and persons engaged) were mainly: import/export trade and wholesale, , ( , ); retail, , ( , ) ; social and personal services, , ( , ) ; professional and business services, , ( , ); financing and insurance, , ( , ); accommodation and food services, , ( , ); real estate, , ( , ) . in the size of the labour force (synonymous with the economically active population) was , , ( , , females). the persons engaged in june included , , people in wholesale, retail and import/export trades, accommodation and food services, , in finance, insurance, real estate, professional and business services, , in the civil service, , in manufacturing and , in construction sites (manual workers only). a minimum wage of hk$ per hour was introduced for the first time on may . unemployment stood at · % in the period sept.-dec. . in the total value of imports was hk$ , , m. and total exports hk$ , , m. the main suppliers of imports in were mainland china ( · %), japan ( · %), taiwan ( · %), singapore ( · %) and usa ( · %). in , · % of total exports went to mainland china, · % to the usa, · % to japan, · % to germany and · % to the united kingdom. the chief import items in were: electrical machinery, apparatus and appliances, etc. ( · %); telecommunications, sound recording and reproducing equipment ( · %); office machines and automatic data processing machines ( · %); articles of apparel and clothing accessories ( · %). the main exports in were: electrical machinery, apparatus and appliances, etc. ( · %); telecommunications, sound recording and reproducing equipment ( · %); office machines and automatic data processing machines ( · %); articles of apparel and clothing accessories ( · %). in there were , km of roads, over % of which were in the new territories. there are road tunnels, including three under victoria harbour. in there were , private cars, , goods vehicles, , buses and coaches, and , motorcycles and mopeds. there were , road accidents in , of which were fatal. a total of · m. tonnes of cargo were transported by road in . a -km bridge linking hong kong, zhuhai in guangdong province in mainland china and macao has been built and was scheduled to open in july following a number of delays. hong kong was ranked fourth for its road infrastructure in the world economic forum's global competitiveness report - . hong kong's railways are run by the mtr corporation limited (mtrcl), a public listed company of which the government is the majority shareholder. the mtr system comprises nine railway lines serving hong kong island, kowloon and the new territories. its -km network has stations and carries an average of · m. passengers each day. mtr lines carried , m. passengers in . in addition, a light rail network ( · km and stops) serves the local communities of tuen mun, yuen long and tin shui wai in the new territories; , passengers travel daily on the system. a high speed rail service between hong kong and guangzhou on the mainland is scheduled to open in late . the electric tramway on the northern state of hong kong island commenced operating in and has a total track length of km. the peak tram, a funicular railway connecting the peak district with the lower levels in victoria, has a track length of · km and two tramcars (each with a capacity of passengers per trip). it carries an average of , passengers daily. the airport express line ( · km) opened in and is also operated by the mtrcl. it carried · m. passengers in . in june it was estimated that · m. passenger journeys were made daily on public transport (including local railways, buses, etc.). in the world economic forum's global competitiveness report - hong kong ranked third for quality of rail infrastructure. the new hong kong international airport (generally known as chek lap kok), built on reclaimed land off lantau island to the west of hong kong, was opened on july to replace the old hong kong international airport at kai tak, which was situated on the north shore of kowloon bay. more than airlines now operate scheduled services to and from hong kong. in cathay pacific airways, the largest hong kong-based airline, operated approximately , passenger and cargo services to destinations in countries and territories around the world. cathay pacific carried , , passengers and · m. tonnes of cargo in . dragonair, a cathay pacific subsidiary, provided scheduled services to cities in mainland china and asia in . in air hong kong, an all-cargo operator, provided scheduled services to bangkok, beijing, ho chi minh city, manila, nagoya, osaka, penang (via bangkok), seoul, shanghai, singapore, taipei and tokyo. hong kong international airport handled more international freight in than any other airport. in , , aircraft arrived and departed and m. passengers and · m. tonnes of freight were carried on aircraft. hong kong was second, behind only singapore, in the rankings for air transport infrastructure in the world economic forum's global competitiveness report - . the port of hong kong handled · m. teus (twenty-foot equivalent units) in , making it the world's third busiest container port after shanghai and singapore. the kwai chung container port has berths with , metres of quay backed by ha. of cargo handling area. at the end of there were , ships ( , ocean-going) of , , gt registered in hong kong. in , , ocean-going vessels, , river cargo vessels and , river passenger vessels arrived at the port of hong kong. a total of m. tonnes of freight were handled in . hong kong was ranked third in the world economic forum's global competitiveness report - for the quality of its port facilities. in there were , , main (fixed) telephone lines (equivalent to · per , population). the local fixed telecommunications network services (ftns) market in hong kong was liberalized in . there were , , mobile phone subscriptions in (equivalent to , · per , population), up from , , in ( , · per , population). the number of subscriptions doubled between and . the internet market has also seen huge growth. in there were , , wireless broadband subscriptions ( · per , population) and , , fixed broadband subscriptions ( · per , population). the number of fixed broadband subscriptions has been declining since as more people have wireless subscriptions instead. in march there were · m. facebook users. the external telecommunications services market has been fully liberalized since jan. , and the external telecommunications facilities market was also liberalized starting from jan. . the hong kong act of provided for hong kong ordinances to replace english laws in specified fields. the courts of justice comprise the court of final appeal (inaugurated july ), which hears appeals on civil and criminal matters from the high court; the high court (consisting of the court of appeal and the court of first instance); the lands tribunal, which determines on statutory claims for compensation over land and certain landlord and tenant matters; the district court (which includes the family court); the magistracies (including the juvenile court); the coroner's court; the labour tribunal, which provides a quick and inexpensive method of settling disputes between employers and employees; the small claims tribunal, which deals with monetary claims involving amounts not exceeding hk$ , ; and the obscene articles tribunal. while the high court has unlimited jurisdiction in both civil and criminal matters, the district court has limited jurisdiction. the maximum term of imprisonment it may impose is seven years. magistracies exercise criminal jurisdiction over a wide range of offences, and the powers of punishment are generally restricted to a maximum of two years' imprisonment or a fine of hk$ , . after being in abeyance for years, the death penalty was abolished in . , crimes were reported in , of which , were violent crimes. , people were arrested in , of whom , were for violent crimes. the population in penal institutions was , at dec. ( per , population). in the adult literacy rate was · % ( · % in ). universal basic education is available to all children aged from six to years. in around three-quarters of the ordinary secondary day schools teaching has been in cantonese since - , with about a quarter of ordinary secondary day schools still using english. in there were , pupils in kindergartens, , in primary schools (including international schools) and , in secondary schools (including international schools). the estimated total government expenditure on education in - was hk$ · bn. ( · % of total government spending and · % of gdp). in - : · % of total government spending and · % of gdp. according to the oecd's pisa (programme for international student assessment) study, -year-olds in hong kong rank second among oecd and other major countries and cities in mathematics and reading, and ninth in science. the three-yearly study compares educational achievement of pupils in over countries. the department of health (dh) is the government's health adviser and regulatory authority. the hospital authority (ha) is an independent body responsible for the management of all public hospitals. in there were , registered doctors, equivalent to · doctors per , population. in there were , dentists, , nurses and , midwives. the total number of hospital beds in was , , including , beds in public hospitals under the ha and , beds in private hospitals. the bed-population ratio was · beds per thousand population. the chinese medicine ordinance was passed by the legislative council in july to establish a statutory framework to accord a professional status for chinese medicine practitioners and ensure safety, quality and efficacy of chinese medicine. in there were , registered chinese medicine practitioners. total expenditure on health in - amounted to hk$ , m., an increase of · % over that in - . social welfare programmes include social security, family services, child care, services for the elderly, medical social services, youth and community work, probation, and corrections and rehabilitation. non-governmental organizations are subsidized by public funds. the government gives non-contributory cash assistance to needy families, unemployed able-bodied adults, the severely disabled and the elderly. caseload as at aug. totalled , . victims of natural disasters, crimes of violence and traffic accidents are financially assisted. estimated recurrent government expenditure on social welfare for - was hk$ · bn. sub-tropical tending towards temperate, with an average temperature of · °c. the number of rainy days is around a third of the year. average annual rainfall varies from - " ( , - , mm) . it is very humid from may to sept. macao's constitution is the 'basic law', promulgated by china's national people's congress on march and in effect since dec. . it is a special administrative region (sar) of the people's republic of china, and is directly under the central people's government while enjoying a high degree of autonomy. the legislative assembly has seats of which are directly elected, indirectly elected by functional constituencies and seven appointed by the chief executive. at the elections held on sept. the macau-guangdong union won two of elected seats with · % of votes cast and the union for development two with · %. ten other parties won a single seat each. turnout was · %. fernando chui sai-on was re-elected chief executive for a second term on aug. , receiving out of votes in the election committee. the economy grew by an average · % per year from - , driven mainly by the gaming sector and the ongoing construction of a number of casino resorts. however, it went into recession from following china's crackdown on government corruption. macao's traditional manufacturing industries virtually disappeared following the transfer of much of the textile industry to the chinese mainland and, in , the termination of the multifibre arrangement, which had governed international textile trade flows for three decades. the unit of currency is the pataca (mop) of avos, which is tied to the hong kong dollar at parity. inflation was · % in and · % in . foreign exchange reserves were us$ , m. in . total money supply was , m. patacas in . in revenues totalled , m. patacas; expenditures, , m. patacas. revenues from gaming tax accounted for · % of total revenue in ; current expenditure accounted for · % of expenditure. real gdp growth was just · % in but then rose to · % in and · % in . more recently the economy contracted by · % in and then by · % in -the lowest rate for any advanced economy that year-owing to a decline in tourism and gaming revenues. total gdp in was us$ · bn. there are two note-issuing banks in macao-the macao branch of the bank of china and the macao branch of the banco nacional ultramarino. the monetary authority of macao functions as a central bank (chairman, teng lin seng). commercial business is handled ( ) by banks, nine of which are local and foreign. total deposits, (including non-resident deposits), , · m. patacas. there are no foreign exchange controls within macao. macao's carbon dioxide emissions from the consumption of energy in were the equivalent of · tonnes per capita. installed capacity was · m. kw in ; production, · bn. kwh. macao imported , m. kwh of electricity in . oil and gas , , litres of fuel oil were imported in . the catch in was estimated at , tonnes. although the economy is based on gaming and tourism there is a light industrial base of textiles and garments. in the number of manufacturing establishments was (food products and beverages, ; textiles and wearing apparel, ; publishing, printing and reproduction of recorded media, ). in a total of , people were in employment, including , ( · %) in gaming and junket activities (up from , in ); , ( · %), hotels, restaurants and similar activities; , ( · %), construction; , ( · %), wholesale and retail trade, repair of motor vehicles, motorcycles and personal and household goods; , ( · %), real estate and business activities; , ( · %), public administration and social security. employment in was · % of the labour force; unemployment rate stood at · %. in imports (c.i.f.) were valued at us$ , · m., of which the main products were telecommunications, sound recording and reproducing equipment; petroleum and petroleum products; and gold, silverware, jewellery and articles of precious materials. in the chief import sources (in us$ m.) were: mainland china ( , · ); hong kong ( · ); japan ( · ). exports (f.o.b.) were valued at us$ · m., of which the leading products were articles of apparel and clothing accessories; gold, silverware, jewellery and articles of precious materials; and petroleum oils and oils obtained from bituminous minerals. in the main export markets (in us$ m.) were: hong kong ( · ); usa ( · ); mainland china ( · ). in there were km of roads. in there were , landline telephone subscriptions (equivalent to · per , inhabitants) and , , mobile phone subscriptions (or , · per , inhabitants). in , · % of households had internet access. in march there were , facebook users. there are a judicial district court, a criminal court and an administrative court with magistrates in all. in there were , crimes, of which , were against property. there were persons in prison in dec. . there are both public and private schools. in - there were schools and colleges. number of students in the - academic year (with number of teachers): pre-primary, , ( ); primary, , ( , ); secondary, , ( , ). in - there were four special education schools with pupils and teachers. there were ten higher education institutions with student enrolment of , . in there were institutions offering vocational training courses, in which participants totalled , . expenditure on education came to · % of gdp in and · % of total government spending in . in there were doctors, dentists and nurses working in primary health care, and doctors, dentists and , nurses working in hospitals. in there were , hospital beds; there were · doctors per , population. in there were an estimated , folk religionists and , buddhists according to the pew research center's forum on religion & public life. a further , people were religiously unaffiliated. there are also small numbers of catholics. the historic centre of macao was inscribed on the unesco world heritage list in . in there were daily newspapers (nine in chinese, three in portuguese and two in english) and weekly newspapers (ten in chinese and one in portuguese). tourism is one of the mainstays of the economy. in there were · m. tourists (of which · m. were from mainland china, · m. from hong kong and · m. from taiwan), up from · m. in and · m. in . visitor spending in totalled , m. patacas. the government-run macao international music festival featuring a wide range of chinese and western music takes place in oct.-nov. in sept. chen shui-bian received a life sentence (later reduced to a -year term) after being found guilty of multiple counts of corruption. china and taiwan signed a free trade agreement in june , which was considered a significant thawing of relations. nonetheless, tensions remained, particularly in relation to disputed sovereignty over several islands in the east china sea. in jan. ma ying-jeou was re-elected to the presidency but the election in jan. was won by tsai ing-wen, whose democratic progressive party won the most seats in legislative polls at the same time-the first occasion that the nationalist party has not been the largest party in government since . beginning with the elections to the seventh legislative yuan held on jan. the legislative yuan has members (formerly ). of the members are elected under the first-past-thepost system in single-member constituencies, are filled by proportional representation in accordance with a nationwide party vote and six are reserved for aboriginal candidates. since the president has been directly elected. since a resolution on the impeachment of the president or vice president is no longer to be instituted by the control yuan but rather by the legislative yuan. the legislative yuan has the power to pass a no-confidence vote against the premier of the executive yuan, while the president of the republic has the power to dissolve the legislative yuan. the premier of the executive yuan is directly appointed by the president of the republic. in dec. a law came into effect allowing for referendums to be held. national anthem 'san min chu i' ('the three principles of the people'); words by dr sun yat-sen, tune by cheng mao-yun. conscription was reduced from months to months in . the government has announced its intention to move towards a volunteer professional force-a process that was originally scheduled to start in and end in but was delayed owing to low recruitment levels. in dec. the defence minister announced that conscription would officially cease in . defence expenditure in totalled us$ , m. (us$ per capita), representing · % of gdp. the republic of china army conducts ground combat missions as well as air support and airborne special operations. it was estimated to number about , personnel in , with reserves numbering · m. its principal role is to defend against a possible amphibious assault from the chinese mainland by the people's liberation army. in addition there are paramilitary forces totalling , personnel. navy personnel in totalled , , with , reservists. the forces consist of four submarines, four cruisers and frigates. there are also missile craft for patrol and coastal defence, mine-laying vehicles and amphibious landing craft. in the air force numbered , personnel with , reservists. there were combat-capable aircraft in the same year including f- es, f- s and mirage - s. by a treaty of dec. the usa pledged to defend taiwan, but this treaty lapsed one year after the usa established diplomatic relations with the people's republic of china on jan. . in april the taiwan relations act was passed by the us congress to maintain commercial, cultural and other relations between usa and taiwan through the american institute in taiwan and its taiwan counterpart, the co-ordination council for north american affairs in the usa, which were accorded quasi-diplomatic status in . the people's republic took over the china seat in the un from taiwan on oct. . in may taiwan ended its formal state of war with the people's republic. taiwan became a member of the world trade organization on jan. . in feb. taiwan had formal diplomatic ties with countries. in aug. , of the diplomatic allies sponsored an unsuccessful proposal for taiwan to join the un. taiwan has made a successful transition from an agricultural economy to one based on high-tech electronics. economic growth averaged % per year over three decades from the s, driven primarily by high value-added manufacturing and exports, especially in electronics and computers. government-owned enterprises, including banks, have been privatized. though largely escaping the impact of the asian financial crisis, the economy went into recession in with the first year of negative growth ever recorded and unemployment reaching record highs. strong export performance stimulated a recovery, with annual gdp growth above % from - . inflation has been consistently low and unemployment, which fell below % in , has averaged between and % since the turn of the century. owing to its heavy dependence on exports, taiwan suffered a severe downturn as a result of the global financial crisis in . major export industries such as semiconductors and memory chips declined, unemployment reached its highest levels since and, in , the economy again went into recession. a us$ · bn. stimulus package boosted recovery and in the economy recorded its highest growth rate for nearly three decades, at · %. however, growth subsequently cooled owing to lower demand from developed nations, averaging · % per year between and . tourism has grown in importance, with over · m. visitors in constituting taiwan's highest annual number to date. an ageing population and high savings rates threaten to constrain domestic demand in the future. the unit of currency is the new taiwan dollar (twd) of cents. gold reserves were · m. oz in dec. . there was inflation of · % in but deflation of · % in . foreign exchange reserves were us$ · bn. in dec. . in general government revenues totalled nt$ , , m. and expenditures nt$ , , m. tax revenue accounted for · % of revenues in ; education, science and culture accounted for · % of expenditures, economic development · % and general administration · %. taiwan sustained rapid economic growth at an annual rate of · % from up to . the rate slipped to · % in the s and · % in ; taiwan suffered from the asian financial crisis, though less than its neighbours. in global economic sluggishness and the events of sept. in the usa severely affected taiwan's economy, which contracted by · %. subsequent economic recovery led to growth of · % in and · % in . there was negative growth of · % in but again the economy bounced back, and grew by · % in , · % in and · % in . the central bank of the republic of china (taiwan), reactivated in , regulates the money supply, manages foreign exchange and issues currency. the governor is yang chin-long. the bank of taiwan is the largest commercial bank and the fiscal agent of the government. there are seven domestic banks, commercial banks and foreign banks. there are two stock exchanges in taipei. taiwan's carbon dioxide emissions from the consumption of energy in were the equivalent of · tonnes per capita. output of electricity in was · m. mwh; total installed capacity was , mw. there were six units in three nuclear power stations in . crude oil production in was , bbls; natural gas, m. cu. metres. taiwan imports most of the oil and natural gas that it consumes. in the cultivated area was , ha., of which , ha. were paddy fields. rice production totalled , , tonnes. livestock production was valued at nt$ , m., accounting for % of taiwan's total agricultural production value. forest area, : , , ha. forest reserves: trees, , , cu. metres; bamboo, , m. poles. timber production, , cu. metres. the catch in was , tonnes, almost exclusively from sea fishing. the first three are container centres, kaohsiung handling · m. -ft equivalent units in , making it the world's th busiest container port in terms of number of containers handled. suao port is an auxiliary port to keelung. in jan. the first legal direct shipping links between taiwanese islands and the chinese mainland in more than years were inaugurated. in there were , , landline telephone subscribers ( · per , inhabitants). taiwan's biggest telecommunications firm, the state-owned chunghwa telecom, lost its fixed-line monopoly in aug. . in there were , , mobile phone subscriptions, equivalent to , · per , persons. in there were · mobile broadband subscriptions per inhabitants and · fixed broadband subscriptions per inhabitants. in march there were · m. facebook users. the judicial yuan is the supreme judicial organ of state. comprising grand justices, since these have been nominated and, with the consent of the legislative yuan, appointed by the president of the republic. the grand justices hold meetings to interpret the constitution and unify the interpretation of laws and orders. there are three levels of judiciary: district courts and their branches deal with civil and criminal cases in the first instance; high courts and their branches deal with appeals against judgments of district courts; the supreme court reviews judgments by the lower courts. there is also the supreme administrative court, high administrative courts and a commission on the disciplinary sanctions of public functionaries. criminal cases relating to rebellion, treason and offences against friendly relations with foreign states are handled by high courts as the courts of first instance. the death penalty is still in force. there was one execution in but none in . the population in penal institutions in april was , ( per , of national population). since there has been compulsory education for six to year-olds with free tuition. the illiteracy rate dropped from · % in to · % by . there were , primary schools, , secondary schools and vocational schools in ; and universities, colleges and junior colleges. in - there were , , pupils with , teaching staff at elementary schools; , pupils and , teaching staff at junior high schools; , pupils and , teaching staff at senior high schools; and , students and , teaching staff at senior vocational schools. there were , , students in universities and colleges in - with , academic staff. in there were , physicians (one for every persons), , doctors of chinese medicine, , nurses, , dentists and assistants, and , pharmacists and assistants. in there were , medical facilities serving , persons per facility; there were , beds and · beds per , persons. in cancers, heart diseases, cerebrovascular diseases, diabetes and accidents were the first five leading causes of death. a universal health insurance scheme came into force in as an extension to social insurance plans that cover only % of taiwan's population. premium shares among the government, employer and insured are varied according to the insured statuses. by the end of , · m. people or % of the population were covered by the national health insurance programme. according to estimates by the pew research center's forum on religion & public life, · % of the population in were folk religionists, · % were buddhists and · % christians. the remainder of the population was either religiously unaffiliated or followed other religions, including taoism. there were daily newspapers in with a circulation of · m. and non-dailies with a circulation of · m. the biggest circulation dailies are the liberty times and apple daily. in there were , , international visitors. receipts totalled us$ , m. the pop festival, spring scream, is held in april in kenting. china in world history chinese politics in the age of deng xiaoping china and the global political economy china: the rise of xi jinping the cambridge encyclopaedia of china the cambridge history of china. vols the politics of hong kong's reversion to china the chinese economy under transition china this century the tragedy of liberation: a history of the chinese revolution china: a modern history china's deep reform: domestic politics in transition chinese capitalism deng xiaoping and the making of modern china the great chinese revolution - the politics of eu-china economic relations china's second continent: how a million migrants are building a new empire in africa china in transition: communism, capitalism and democracy sowing the seeds of democracy in china: political reform in the deng xiaoping era historical dictionary of the chinese cultural revolution the rise of modern china china: a macro history tombstone: the untold story of mao's great famine china's economy: what everyone needs to know all under heaven: a complete history of china chinese politics in the hu jintao era: new leaders, new challenges the people's republic of amnesia: tiananmen revisited chinese foreign policy in a changing world chinese economy in the s the politics of china: sixty years of the people's republic of china the party: the secret world of china's communist rulers. .-asia's reckoning: china, japan and the fate of us power in the pacific century china's war with japan, - : the struggle for survival social and political development in post-reform china age of ambition: chasing fortune, truth and faith in the new china a revolutionary life at the crossroads of post-communist modernisation: russia and china in comparative perspective a history of china wealth and power: china's long march to the twenty-first century mao's road to power: revolutionary writings - . vols china goes global: the partial power the chinese century: the rising chinese economy and its impact on the global economy, the balance of power, and your job the china-pakistan axis: asia's new geopolitics the chan's great continent: china in western minds eldest son, zhou enlai and the making of modern china india's and china's recent experience with reform and growth critical issues in contemporary china making china strong other more specialized titles are listed under territory and population; tibet; agriculture further reading statistical information: the census and statistics department is responsible for the preparation and collation of government statistics. these statistics are published mainly in the hong kong monthly digest of statistics. the department also publishes monthly trade statistics, economic indicators and an annual review of overseas trade hong kong's transitions the politics of hong kong's reversion to china the end of hong kong: the secret diplomacy of imperial retreat the hong kong story the final years of british hong kong: the discourse of colonial withdrawal last post: the end of empire in the far east the politics of democratization in hong kong historical dictionary of hong kong and macau china: a political history of the british crown colony's transfer to chinese rule managing china's sovereignty in hong kong and taiwan the democratic progressive party won seats ( constituency and proportional); the nationalist party, ( constituency and proportional); the new power party, ; the people first party, ; the non-partisan solidarity union, ; ind., . current government president: tsai ing-wen; b. (nationalist party/kuomintang foreign affairs; health and welfare; interior; justice; labour; national defence; science and technology national defence: yen de-fa. science and technology: chen liang-gee. transportation and communications: ho chen-tan tang feng; lo ping-cheng coast guard administration: lee chung-wei. environmental protection administration: lee ying-yuan. fair trade commission: huang mei-ying. financial supervisory commission: koo lihsiung. hakka affairs council: lee yung-te. council of indigenous peoples: icyang parod. mainland affairs council: chen ming-tong. national communications commission: chan ting-i. overseas community affairs council: wu hsin-hsing. directorate general of personnel administration: shih ning-jye. veterans' affairs council: lee shying-jow hon hai precision industry, an electronics manufacturer (us$ · bn.); and chunghwa telecom (us$ · bn metres; integrated circuit packages, · trn. units; global positioning system (gps) sets, · bn. units. labour in the average total labour force was · m., of whom · m. were employed. of the employed population, · % worked in manufacturing · % in construction; · % in accommodation and food services buses and coaches, · m. lorries and vans, and · m. motorcycles and mopeds were in use. , m. passengers and m. tonnes of freight were transported in . there were , fatalities in road accidents in . rail in freight traffic amounted to · m. tonnes and passenger traffic to m. total route length was , km. there are metro systems in taipei civil aviation there are currently two international airports: taiwan taoyuan international airport at taoyuan near taipei, and kaohsiung international in the south there were ships of gt or over registered, totalling · m. gt. of the vessels registered, were general cargo ships, bulk carriers, container ships, oil tankers and nine passenger ships. there are six international ports statistical yearbook of the republic of china. annual. the republic of china yearbook. annual. taiwan statistical data book. annual. annual review of government administration the other taiwan: to the present day historical dictionary of taiwan national identity and status in international society managing china's sovereignty in hong kong and taiwan the shadow of china: political developments in taiwan since national statistics website the climate is subtropical in the north and tropical in the south. the typhoon season extends from july to sept. the average monthly temperatures of jan. and july in taipei are · °f ( · °c) and · °f ( · °c) respectively, and average annual rainfall is · " ( , · mm). kaohsiung's average monthly temperatures of jan. and july are · °f ( · °c) and · °f ( · °c) respectively, and average annual rainfall is · " ( , · mm). the roc constitution is based on the principles of nationalism, democracy and social wellbeing formulated by dr sun yat-sen, the founding father of the republic of china. the roc government is divided into three main levels: central, provincial/ municipal and county/city, each of which has well-defined powers.the central government consists of the office of the president, the national assembly, which is specially elected only for constitutional amendment, and five governing branches called 'yuan', namely the executive yuan, the legislative yuan, the judicial yuan, the examination yuan and the control yuan. key: cord- -d f fd x authors: de jong, menno douwe title: avian influenza viruses and pandemic influenza date: journal: new and evolving infections of the st century doi: . / - - - - _ sha: doc_id: cord_uid: d f fd x nan global outbreaks with high death tolls. these pandemic strains can certainly be regarded as (re)emerging pathogens. the "athen's plague" described by hippocrates' contemporary thucydides is believed by some to constitute the first account of such a devastating influenza epidemic. since the th century, many large-scale outbreaks of influenza-like illnesses have been described in europe. in , one of such outbreaks spread from europe into africa and asia, possibly making it the first recorded influenza pandemic. the most devastating influenza pandemic in modern recorded history, known as the "spanish flu," occurred in - , killing up to million people worldwide. other less destructive pandemics during the past century occurred in and . avian influenza a viruses are key to the emergence of human influenza pandemics. the virus strains implicated in the th century's influenza pandemics originated directly from avian influenza viruses, either through genetic reassortment between human and avian influenza strains ( , ) or possibly through adaptation of purely avian strains to humans ( ) . it was long thought that the host range of avian influenza viruses precluded direct transmission to humans and that the emergence of pandemic strains required genetic reassortment between avian and human strains. however, occurrences of direct bird-to-human transmission of avian influenza viruses have increasingly been reported in recent years, culminating in the ongoing outbreaks of influenza a (h n ) among poultry and wild birds in several asian, european and african countries with continuing instances of human infections. these unprecedented developments have resulted in increasing global concerns about the (re)emergence of pandemic influenza a strains and the role of avian influenza viruses in this. influenza viruses are pleomorphic, enveloped rna viruses belonging to the family orthomyxoviridae. protruding from the lipid envelope are two distinct glycoproteins: the hemagglutinin (ha) and neuraminidase (na) . ha attaches to cell-surface sialic acid receptors, thereby facilitating entry of the virus into host cells. because it is the most important antigenic determinant to which neutralizing antibodies are directed, ha represents a crucial component of current vaccines. na is the second major antigenic determinant for neutralizing antibodies. by catalyzing the cleavage of glycosidic linkages to sialic acid on host cell and virion surfaces, this glycoprotein prevents aggregation of virions thus facilitating the release of progeny virus from infected cells. inhibition of this important function represents the most effective antiviral treatment strategy to date. a third membrane protein, the m protein, is present in small quantities in influenza a viruses. by functioning as an ion channel, this protein regulates the internal ph of the virus, which is essential for uncoating of the virus during the early stages of viral replication. this function is blocked by the antiviral drugs amantadine and rimantadine. the genome of influenza viruses is segmented, consisting of eight single-stranded, negative-sense rna molecules that encode proteins. the rna segments are contained within the viral envelope in association with the nucleoprotein (np) and three subunits of viral polymerase (pa, pb , and pb ), which together form the ribonucleoprotein (rnp) complex responsible for rna replication and transcription. additional proteins contained within the virion include m and the viral nuclear export protein (nep), which function in assembly and budding and in export of rnp from the nucleus, respectively. the only nonstructural protein of influenza a viruses is ns , which has multiple functions in viral replication and is also thought to counteract interferon activity of the host thereby evading the immune response. based on antigenic differences in np and m proteins, influenza viruses are classified as types a, b, and c. influenza b and c viruses are not divided into subtypes. all avian influenza viruses are classified as type a. further subtyping of influenza a viruses is based on antigenic differences between the two surface glycoproteins ha and na. to date, ha subtypes (h -h ) and na subtypes (n -n ) of influenza a viruses have been identified (fouchier et al., ) . the standard nomenclature for influenza viruses include the influenza type, the host of origin (excluding humans), the place of isolation, the strain number, the year of isolation, and finally the influenza a subtype in parentheses (e.g., a/duck/vietnam/ / [h n ]). the natural reservoir of influenza a viruses are aquatic birds, in which the viruses appear to have achieved an optimal level of host adaptation and do not cause disease . from this principal reservoir, viruses are occasionally transmitted to other animals, including mammals and domestic poultry, causing transitory infections and outbreaks. through adaptation by mutation or genetic reassortment, some of these viruses may establish species-specific permanent lineages of influenza a viruses and cause epidemics or epizootics in the new host. in the human population, the establishment of these lineages in the th century was preceded by influenza pandemics. transmission of viruses and transitory infections may also occur among the new hosts (e.g., between humans and pigs or chickens and humans). although all ha and na subtypes are found in aquatic birds, the number of subtypes that have crossed the species barrier and established stable lineages in mammals is limited. only three ha and two na subtypes (i.e., h n , hin , h n , and h n ) have circulated in humans since . in horses, only two influenza a subtypes (h n and h n ) are found, while, despite susceptibility to all avian subtypes in experimental settings, the only subtypes recovered from pigs in nature are h , h , n , and n . the molecular, biological, or ecological factors determining the apparent subtype-specific ability of viruses to cross species barriers and spread among a range of hosts remain largely unresolved. although interspecies transmission does occur at times, there certainly are host-range restrictions. for example, avian influenza viruses usually do not replicate efficiently in humans and vice versa (hinshaw et al., ; beare and webster ) . relatively little is known about the viral and host factors governing the host range of influenza viruses and the mechanisms by which species barriers are crossed. however, in view of their role in entry of the virus, the viral ha glycoproteins and their sialic acid receptors on host cells clearly are important determinants of host-range restrictions. human influenza strains preferentially bind to sialic acid residues linked to galactose by the α , linkage, and avian and equine influenza strains recognize sialic acid linked to galactose by α , linkage rogers and d'souza ; connor et al., ; gambaryan et al., ; matrosovich et al., matrosovich et al., , . correspondingly, human respiratory epithelial cells predominantly contain α , sialic acid-galactose linkages, whereas the host cells in birds and horses mainly contain α , linkages (couceiro et al., ; ito et al., ; matrosovich et al., ) . interestingly, in contrast with the human respiratory tract, epithelial cells in the human eye predominantly contain α , -linked sialic acid receptors, which may explain why conjunctivitis is a common symptom of human infections with avian influenza viruses (paulsen et al., ; terraciano et al., ; diebold et al., ) . it has been hypothesized that, by serving as the main port of entry and site of initial replication, the eye may play a role in the adaptation of avian influenza viruses to humans (olofsson et al., ) . the presence of α , -linked sialic acid receptors has also recently been demonstrated in the lower respiratory tract of humans, i.e. on bronchiolar and alveolar cells, which may explain the propensity of avian h n viruses to cause pneumonia and not upper respiratory illnesses, in humans (shinya et al., ; van riel et al., ) . respiratory epithelial cells in the pig contain both α , and α , linkages, which explains why this animal is susceptible to both human and avian influenza viruses . because of this trait, the pig is widely regarded as a potential source of new pandemic strains, because it could serve as a nonselective host in which mixed infection of avian and human strains efficiently occurs, potentially resulting in new reassortant viruses, or in which purely avian strains can adapt to human receptor recognition (figure . ). the receptor specificity of ha for either of the two sialic acid-galactose linkages is determined by the structure of the receptorbinding site of ha. although several residues have been implicated, the amino acids at positions and particularly seem to determine ha receptor specificity, that is, glu- and gly- are predicted to have affinity for avian and equine receptors, whereas leu- and ser- confer specificity for human receptors (wilson et al., ; naeve et al., ; weis et al., ; suzuki et al., ) . albeit less important, substrate specificity of na for either α , or α , -linked sialic acid also contributes to the efficiency of viral replication in different hosts (hinshaw et al., ) . this is illustrated by the fact that during its evolution in humans, the na of h n viruses, which were of avian origin and therefore highly specific for hydrolization of α , -linked sialic acids, acquired high affinity for the human α , -linked sialic acids (baum and paulson, ) in addition to the surface glycoproteins, laboratory experiments with reassortant viruses suggest that the genes encoding internal proteins, such as m, np, pb and pb , may also play a role in determining the host range (almond ; scholtissek et al., a; snyder et al., ; subbarao et al., ) . however, because most of these experiments evaluated reassortant viruses with different constellations of gene segments, it remains difficult to interpret whether the proteins themselves contribute to host-range restrictions or whether certain combinations of gene segments from different origins are incompatible. manipulation of the genome using reverse genetics approaches will undoubtedly provide more definitive insight in the role of other host range determinants. antigenic variation of influenza a viruses can occur gradually by accumulation of point mutations (antigenic drift) or drastically by genetic reassortment (antigenic shift). antigenic drift, driven by immunological pressure on ha and na, allows the virus to evade the immune response and is the reason that influenza viruses manage to cause yearly epidemics. it is also because of antigenic drift that periodic replacements of human vaccine strains are needed. in contrast with human and other non-avian influenza strains, antigenic drift in avian viruses is very limited despite similar mutation rates (austin and webster, ; kida et al., ; liu et al., ) . most likely, this reflects optimal adaptation of these viruses to the host resulting in limited immunological pressure and consequent evolutionary stasis of these viruses in their natural reservoir. drastic changes in antigenicity can occur through the acquisition of completely new surface proteins by genetic reassortment . the segmented nature of the influenza virus genome facilitates the exchange of genes between two viruses (e.g., human and avian strains) that coinfect a host cell. although such exchange can result in possible combinations of the eight different genomic segments of the virus, antigenic shift only arises when the reassortment at least includes the ha gene. provided that the reassortant virus is efficiently transmissible from infected to noninfected hosts, such an antigenically novel virus strain has pandemic potential when introduced in a population that completely lacks immunity against the new surface protein (figure . a). the pig is regarded as the ideal host for reassortment in view of its equal susceptibility for human and avian influenza strains . however, the increasing reports of bird-to-human transmissions of avian viruses indicate that coinfections, and consequently reassortments, could also take place in humans. beside genetic reassortment, antigenic shift is also caused by direct transmission of non-human influenza viruses to humans, as occurred or is still occurring on a relatively large scale in hong kong in (h n ), in the netherlands in (h n ), and in asia, the middle east, europe and africa since (h n ) (yuen et al., ; fouchier et al., ; hien et al., a) . as is true for reassortant viruses, these viruses are of pandemic potential when acquiring the ability for efficient transmission between humans through adaptation in either humans or an intermediate host (figure . b). finally, antigenic shift can occur when a previously circulating human influenza virus reemerges after an extended period of time. this happened in when h n virus, which circulated in the s, reappeared in the human population ("russian flu"), possibly after escaping a laboratory (nakajima et al., ; scholtissek et al., b) . the reemergence of this virus gave rise to a relatively mild pandemic affecting mainly young persons who were still immunologically naive to this subtype. the same could have happened in , when h n virus, which had disappeared from the human population after the emergence of h n viruses in , was inadvertently sent to more than laboratories worldwide as part of an external quality assurance scheme (enserink, ) . avian influenza viruses can infect a wide range of domestic and wild birds, including (but not restricted to) chickens, ducks, turkeys, geese, quail, pheasants, seabirds, shore birds, and migratory birds. in these natural hosts, influenza viruses replicate in the gastrointestinal tract and are secreted in large amounts into the feces (webster et al., ) . transmission between birds occurs directly or indirectly through fecally contaminated aerosols, water, feed, and other materials. the spectrum of disease in birds ranges from asymptomatic infection, to mild respiratory illness, to severe and rapidly fatal systemic disease. most avian influenza viruses isolated from birds are avirulent (i.e., result in asymptomatic infection or only mild disease). avian influenza viruses capable of causing outbreaks of severe disease (fowl plague) in chickens or turkeys are classified as highly pathogenic and are currently restricted to h and h subtypes. typically, these highly pathogenic strains do not cause disease in ducks or geese. infection of poultry by highly pathogenic avian influenza viruses is characterized by disseminated infection and clinically manifested by decreased egg production, respiratory signs, excessive lacrimation, edema of the head, diarrhea, neurological symptoms, and death. the knowledge concerning the viral factors that determine the pathogenicity of influenza viruses is limited and is primarily derived from studies of highly pathogenic avian influenza viruses. a broad tissue tropism and the ability to replicate systemically are the hallmarks of these viruses. the most important and well-studied molecular correlate of these properties resides in the cleavability of the ha precursor glycoprotein (webster and rott, ; garten and klenk, ; steinhauer, ) . in the viral life cycle, post-translational cleavage of the precursor ha molecule into two subunits (ha and ha ) by host proteases is essential for infection to proceed. this cleavage generates a fusogenic domain at the amino terminus of ha that mediates fusion between the viral envelope and the endosomal membrane. has of avirulent avian influenza strains are cleaved only in a limited number of cell types, resulting in localized respiratory or gastrointestinal infections and mild illness. in contrast, has of highly pathogenic h and h strains can be cleaved in several different host cells, resulting in a broad cell tropism and the ability of causing systemic infection (klenk and garten, ; senne et al., ) . this apparent promiscuity of ha for a broad range of cellular proteases is determined by the structure of the ha cleavage site: has with high cleavability (i.e., from highly pathogenic strains) have multiple basic amino acid residues immediately upstream of the cleavage site, whereas has from avirulent subtypes usually have only a single arginine residue at this site (bosch et al., ; walker and kawaoka, ; senne et al., ; chen et al., ) . evidence for the correlation between a multibasic cleavage site, susceptibility for proteases and virulence has been provided by experiments in which viruses were generated with altered cleavage sites in otherwise unchanged genetic backgrounds (ohuchi et al., ; horimoto and kawaoka, ) . the reason why multibasic cleavage sites seem restricted to the has of h and h subtypes is unclear but may suggest that the number of basic residues is limited by structural features of ha. analyses of nucleotide sequences of h and h ha genes has shown the occurrence of direct repeats of purine-rich sequences (aagaaa) at the cleavage site in many cases . such repeats may arise because of pausing of the transcriptase-complex at a region of secondary structure, resulting in slippage of the complex and insertion of a short repeat sequence. additionally, recombination events between two genes of the same virus (e.g., from m or np to ha) may result in the insertion at the cleavage site of short sequences that code for multibasic amino acid residues (orlich et al., ; suarez et al., ) . in addition to the presence of multiple basic amino acids, susceptibility to ubiquitous proteases is also determined by the loss of a glycosylation site in the vicinity of the cleavage site (deshpande et al., ; webster, , ) . although ha clearly is an important determinant of viral pathogenicity, animal studies indicate that virulence in mammals is a polygenic trait involving a constellation of other genes that can vary with the specific virus strain and host . however, besides ha, two genes have specifically been implicated in viral pathogenicity in mammals; that is, pb and ns. by reverse genetics experiments, it has been shown that a lysine residue at position (lys ) of pb seems essential for high virulence and systemic replication in mice of highly pathogenic influenza h n viruses responsible for the outbreak among poultry and humans in hong kong in (h n / ) (hatta et al., ) . the presence of lys in pb of h n / viruses appears to determine the viral replicative efficiency in mouse cells (and not avian cells) but does not increase the tissue tropism of the virus in mice . lys has also been found in pb s of some, but not all highly pathogenic h n and h n viruses isolated from humans during the outbreaks of these viruses among poultry and humans in (the netherlands) and (viet nam, thailand), respectively li et al., ) . interestingly, a lysine residue at position of pb is also present in all human influenza subtypes (h , h , h ) (webster, ) . furthermore, single-gene reassortant viruses carrying a pb gene of avian origin and all other genes from a human virus showed efficient replication in avian but not mammalian cells (subbarao et al., ) . this host cell restriction could be traced to a glutamic acid residue at position of the avian pb instead of a lysine residue at the same position in the human virus (subbarao et al., ) . these observations suggest that an amino acid change to lys in pb may help avian viruses to adapt to efficient replication in mice and possibly other mammals, thereby increasing the virulence in these hosts. reverse genetics experiments with highly pathogenic avian influenza h n and h n viruses have indicated that other members of the viral polymerase complex beside pb , i.e. pa and pbi, likely also play a role in adaptation of avian viruses to the mammalian host, suggesting that host factors are important for viral polymerase activity (gabriel et al., ; salomon et al., ) . in addition to pb , the ns gene seems to play a role in the pathogenesis of avian and human influenza virus infections. this gene encodes two proteins: the nuclear export protein (nep) and the only nonstructural protein of influenza viruses, ns . the ns gene or its product contribute to viral pathogenesis by allowing the virus to evade the interferon response of the host (garcia-sastre, krug et al., ) . this evasion may occur through multiple mechanisms, including interference with the activation of cell-signaling pathways and protein kinases involved in interferon induction or interference with the maturation of cellular pre-mrna at the post-transcriptional level. the ns gene has also been implicated in determining the high pathogenicity of influenza h n / viruses in mammals. experiments in pigs using recombinant viruses showed that the presence of the ns gene of h n / viruses greatly increased the pathogenicity of an h n virus, possibly by escaping the antiviral effects of interferons and tumor necrosis factor alpha (tnf-α) seo et al., , . this enhanced virulence in pigs required the presence of glutamate instead of aspartate at position (glu- ) of the h n ns gene, but this amino acid change has not been found in all highly pathogenic h n viruses isolated from humans or animals . beside the apparent cytokine resistance of h n / viruses, in vitro studies in human macrophages and respiratory cells showed that these viruses also seem to induce the transcription of proinflammatory cytokines, in particular tnf-α and interferon-β, and that the ns gene contributes to this induction (cheung et al., ; chan et al., ) . similar results were obtained in mice, in which infection with a recombinant h n virus containing the h n / ns gene caused a cytokine imbalance in mouse lungs, characterized by increased concentrations of proinflammatory cytokines and decreased levels of anti-inflammatory cytokines (lipatov et al., a) . cytokine dysregulation by h n / viruses is also suggested by observations in human infections. pathological examination of patients who died of influenza h n infection during the outbreak in hong kong showed reactive hemophagocytic syndrome, which is believed to be a cytokine-driven condition, as the most prominent feature . in addition, exceptionally high levels of certain chemokines were observed in the serum of human cases with avian influenza h n . together, these observations may suggest that a combination of increased resistance against, and high induction of cytokines by the virus synergistically lead to a profound cytokine dysregulation that may play a role in explaining the severity of illness in mammals, including humans. although the ns gene seems to play a crucial role in this, it is likely that other particular gene constellations involving different internal genes also contribute. the virulence of highly pathogenic avian influenza viruses is clearly influenced by the specific host. two variants of the h n / virus, one of which was isolated from a human patient with mild repiratory illness and the other from a fatal human case, displayed similar differential pathogenicity in mice (zitzow et al., ) . however, in ferrets, both variants caused indistinguishable severe systemic disease (zitzow et al., ) . conversely, experimental infection with h n / viruses exhibiting high virulence in mice caused localized respiratory illness without systemic spread in primates and only viral replication in the respiratory tract without clinical illness in pigs rimmelzwaan et al., ) . the host factors determining the clinical outcome in animals are unclear. the clinical outcome of human influenza is influenced by factors such as the patient's age, the level of preexisting immunity, immunosuppression, comorbidities, pregnancy, and smoking habits, indicating that host-related factors certainly contribute to pathogenesis in humans. most of the above factors may be explained by differences in local, innate, or specific immunity at different stages of life or under specific circumstances, but other factors likely also play a role. for example, the observation that influenza-related encephalopathy seems well-recognized in japan but less so in other countries may suggest that there are differences in proneness for certain disease manifestations among populations, possibly related to genetic differences (morishima et al., ; sugaya, ) . although evidence is lacking at present, it is not unlikely that host factors also play a role in the the susceptibility and pathogenesis of human infections with avian influenza viruses. introduction of an influenza a virus with a novel ha gene in a population that lacks immunity to this ha has the potential to cause a pandemic when the virus posesses the ability to spread efficiently among humans (figure . ). during the th century, this has happened three times, in , , and , killing millions of people worldwide. in all three pandemics, the viruses originated from avian influenza viruses. the virus strains responsible for the influenza pandemics of and both first emerged in southeastern asia, and both arose through reassortment of genes between avian viruses and the prevailing human influenza strain (scholtissek et al., c) . the "asian influenza" pandemic of was caused by an h n virus that had acquired three genes (h , n , and pb ) from avian viruses infecting wild ducks, in a backbone of the circulating h n human influenza strain. as the asian flu strain emerged and established a permanent lineage, the h n strains soon disappeared from the human population for unclear reasons. similarly, the h n virus causing the "hong kong influenza" pandemic of (a) (b) figure . . mechanisms for generation of a pandemic influenza a strain. pandemic influenza a strains could result from genetic reassortment involving the hemagglutinin gene between avian and human strains in coinfected pigs or humans, followed by adaptation to human receptors in either host and human-to-human transmission (a); or through adaptation to humans of a purely avian influenza strain, either in humans or in an intermediate host such as the pig (b). mechanism a was implicated in the "asian" ( ) and "hong kong" ( ) influenza pandemics. the h n virus that caused the "spanish flu" influenza pandemic of likely resulted from mechanism b. consisted of two genes from a duck virus (h and pb ) in a background of the human h n strain circulating at that time. the latter virus disappeared with the emergence of the h n virus and since then has not been detected in humans. sequence analysis of the hypothetical precursor strain that immediately preceded the pandemic h n virus suggested that fewer than six amino acids in ha had changed during the avian-to-human transition . interestingly, a number of these changes may reflect adaptation to the new host because they modified the area surrounding the receptor-binding pocket of ha, including a glu to leu change at position , which is particluarly implicated in determining specificity for human receptors (see section . . ). the fact that beside one or two novel surface glycoproteins, both pandemic strains also posessed a pb gene of avian origin is intriguing and may suggest a role of this gene in interspecies transmission . although millions of people died during the and pandemics, the viruses involved did not appear particularly virulent, suggesting that lack of immunity was the main reason for the excess mortality. this was different during the "spanish flu" pandemic of , in which lack of immunity in the human population was combined with an apparent extremely high virulence of the virus, resulting in the demise of up to million people worldwide. because the pandemic occurred before viruses were identified as the causative agents, no intact virus has been available for analysis. this and the similar lack of available human and animal influenza strains circulating before has made it difficult to determine the exact origin of the pandemic h n virus and the reason for its extreme virulence. however, valuable insight has been provided by the recovery of fragments of viral rna isolated from archived autopsy specimens and tissue from alaskan flu victims buried in the permafrost (taubenberger et al., ) . this enabled sequence analysis of all eight genes of the virus (reid et al., ; taubenberger et al., ) . phylogenetic analyses of these genes suggest that the h n virus may not have arisen by the same mechanism as the and pandemic viruses (i.e., by reassortment of avian and human influenza viruses) but perhaps by direct transmission from an avian source after adaptation in humans or another permissive mammalian host, such as the pig (reid et al., ; taubenberger et al., ) . this is supported by the observation that human h n strains, including the pandemic strain, have retained the amino acid residues at positions and of ha predictive for binding to avian receptors (see section . . ) (taubenberger et al., ) . recent crystallographic studies showed that structural changes in the h ha allowed the virus to recognize human receptors despite the presence of these avian-like residues, which may explain why the virus could nevertheless efficiently infect and spread among humans (gamblin et al., ; stevens et al., ) . the possibility that the strain had retained the structure and biological properties of its avian ancestors while acquiring the ability to recognize and efficiently infect human cells may explain the high virulence of this virus. mathematical modeling studies have suggested that the transmissability of the virus was not remarkably different than regular human influenza strains, indicating that extremely efficient spread did not account for the high morbidity and mortality (mills et al., ) . although part of the high mortality of the pandemic could be explained by the lack of antibiotics to treat secondary bacterial pneumonia and poor living conditions, the extremely rapid and severe clinical course implies high pathogenicity of the virus as the major cause. the molecular basis for this high virulence remains unclear. the h ha lacks the multibasic cleavage site characteristic of highly pathogenic avian influenza viruses (see section . . ) (taubenberger et al., ; reid et al., ) . there are conflicting observations concerning the role of the ns gene in the pandemic strain. in mice, the presence of the complete ns or only the ns segment seemed to confer decreased, rather than enhanced pathogenicity of reassortant h n viruses (basler et al., ) . in contrast, in vitro experiments in human lung cells suggested more efficient inhibition of interferon-regulated genes by h n virus in the presence of the ns gene (geiss et al., ) . the most convincing evidence implicates ha as an important determinant of the high virulence. the presence of ha of the virus conferred high pathogenicity in mice to human strains that were otherwise non-pathogenic in this host . furthermore, these infections were associated with severe hemorrhagic pneumonia and the induction of high levels of macrophage-derived cytokines and chemokines, strikingly reminiscent of clinical observations in humans during the spanish flu pandemic, as well as of recent in vitro and in vivo observations of infections with highly pathogenic avian influenza h n viruses (oxford ; cheung et al., ; peiris et al., ). before the year , a few isolated cases of human infections with highly pathogenic h n viruses were reported. these infections concerned laboratory accidents involving exposure to viral cultures or infected animals, and in one case presumed exposure to infected waterfowl in the absence of an overt outbreak (delay et al., ; campbell et al., ; taylor and turner, ; webster et al., ; kurtz et al., ) . all reported cases, except one, were clinically characterized by selflimiting conjunctivitis. influenza h n virus was isolated from blood of one patient wih hepatitis, but the clinical relevance of this finding was unclear as was the source of this infection (delay et al., ; campbell et al., ) . in , a large-scale outbreak of h n viruses decimated the poultry industry in the netherlands and was associated with several human infections koopmans et al., ) . after diagnosing the first case of human infection with h n virus, active case finding among exposed persons and their close contacts identified a total of laboratory-confirmed infections in humans . this amounted to approximately % of the estimated number of people potentially exposed to the virus. highest infection rates were observed in veterinarians and chicken cullers. of the h n cases, persons presented with conjunctivitis, of whom also complained of influenza-like symptoms koopmans et al. ). it cannot be excluded that the remaining six patients also had conjunctivitis. although two individuals reported an influenza-like illness only, one had suffered a previous eye injury that precluded evaluation of conjunctivitis, while the other had chronic blepharitis. four individuals did not fit any case definition, either because of missing data or because they complained of red eyes only and therefore did not meet the criteria for a diagnosis of conjunctivitis. the prominence of conjunctivitis as the presenting syndrome in these and other reported human cases of influenza h n is striking and may be explained by the presence of α , -linked sialic acid receptors in the eye, which are preferentially recognized by ha of avian influenza viruses, including h n subtypes (see section . . ) (olofsson et al., ) . the observation that, in contrast with human influenza strains, viral loads in conjunctival specimens of the dutch h n -infected individuals seemed higher than in respiratory specimens, supports the notion that h n virus may replicate efficiently in cells in or near the eye and not in the respiratory tract . six of the seven cases of influenza-like illnesses were mild. one patient, a previously healthy -year-old veterinarian, complained of fever and headache days after visiting an infected farm . he subsequently developed pneumonia complicated by acute respiratory distress syndrome and multiorgan failure, of which he died days after the onset of illness. autopsy revealed pathologic changes in the lungs similar to those found in influenza h n -infected humans and no significant abnormalities in other organs. direct human-to-human transmission of h n virus during the dutch outbreak is suggested by the fact that three individuals with confirmed infections had not been in direct contact with infected poultry but were family members of poultry workers with h n conjunctivitis . the h n virus causing the outbreak in the netherlands most likely evolved from a low pathogenic virus from wild ducks after the introduction of this virus into the poultry population . in agreement with its classification as a highly pathogenic avian influenza virus, the ha contained multiple basic amino acids at the cleavage site. sequence comparison of virus isolates from chickens and humans, including those implicated in human-to-human transmission, revealed virtually no differences, indicating no significant accumulation of mutations on bird-to-human or human-to-human transmission. the only exception was the virus isolated from the fatal case, which showed a total of amino acid substitutions not seen in the other isolates. most of these substitutions involved the ha, na, and pb genes, which have all been implicated as determinants of host range and pathogenicity. intriguingly, the mutations in pb included a glutamine to lysine change at positions , associated with high virulence of h n viruses in mice (see section . . ) . the h n outbreak in poultry was effectively contained by the culling of approximately million chickens, which amounts to about % of the total chicken population in the netherlands . after the first human infections were identified, individuals exposed to potentially infected chickens were vaccinated with the available human vaccine to prevent possible dual infection with human and avian strains and the resulting risk of reassortment. as the outbreak progressed, the recommendation for vaccination was extended to all poultry farmers in a -km radius of infected farms and to persons suspected of h n infection. in addition, a prophylactic regimen of the neuraminidase-inhibitor oseltamivir was started for all people handling potentially infected poultry to prevent bird-to-human transmission and human-to-human transmission of avian viruses. prophylactic treatment was to be continued for days after the last exposure. these control measures may serve as a model for the control of emerging influenza viruses because they, at least theoretically, minimize the possibility that the virus spreads among the human population. in early , an outbreak of highly pathogenic h n viruses occurred in poultry farms in british columbia, canada . the causative virus probably had evolved by homologous recombination between the ha and m genes in a low pathogenic h n virus . this recombination event resulted in the introduction of a multibasic sequence at the cleavage site of ha. surveillance among potentially exposed people identified two laboratory-confirmed cases of h n infection. in these cases, conjunctivitis and mild influenza-like symptoms (coryza, headache) developed - days after exposure . both were treated with oseltamivir and recovered fully. no secondary cases were identified. the outbreak among poultry was contained by extensive culling. control measures in potentially exposed people were similar to those during the dutch h n outbreak. in , human infections with h n viruses were reported in two unrelated children from hong kong, aged and years (peiris et al., ) . both children had a mild influenza-like syndrome, associated with mild lymphopenia in one, and slightly raised transaminase levels in the other child. neither child developed pneumonia and both recovered uneventfully within - days. there was a history of probable contact with live chickens in one of the patients, but otherwise the source of transmission was unclear. no serological evidence of h n infection was found in the children's family members or health care workers. three serum samples from volunteer blood donors in hong kong showed the presence of neutralizing antibodies against h n virus, suggesting that additional infections had occurred in hong kong (peiris et al., ) . around the same time as the infections in hong kong, five additional, similarly mild cases of human h n in humans were reported from mainland china . the human infections in hong kong and mainland china were caused by non-highly pathogenic h n viruses of two disinct lineages. the hong kong virus was related to a quail h n virus (a/quail/hk/ g / [h n ]) and possessed internal genes similar to the h n virus that caused the outbreak in poultry and humans in (guan et al., lin et al., ) . this may suggest that the quail h n virus has been the donor of all internal genes to the h n outbreak strain (guan et al., ) . the strains isolated from humans in mainland china were related to a different lineage of h n viruses found in ducks and chickens (a/duck/hk/y / [h n ] and a/chicken/hk/g / [h n ]) (guo et al., ) . most h n strains isolated since seem to be related antigenically to the latter virus but posess a variety of internal gene constellations, including those of h n / -like origin (choi et al., ; lipatov et al., ) . interestingly and perhaps concerning, h n viruses isolated from poultry have acquired a preference for binding to the human-like α , sialic acid-galactose linkages, which may suggest that certain species of poultry could act as an intermediate host in the zoonotic transmission of influenza viruses from their natural reservoir in acquatic birds to mammals, including humans (matrosovich et al., ) . indeed, h n viruses have also been isolated from pigs in southeastern china, indicating widening of the host range (peiris et al., ) . in addition, contemporary human h n strains are cocirculating in southeastern chinese pigs, providing ideal circumstances for potential genetic reassortment leading to the emergence of viruses with pandemic potential (peiris et al., ). in recent years it has become clear that, in contrast with the usually mild illnesses caused by h and h n viruses, human infections with highly pathogenic influenza h n viruses are associated with severe, often fatal disease. in may , after outbreaks of influenza h n among poultry on three farms in the new territories of hong kong, an influenza h n virus was isolated from a -year-old boy in hong kong, who died of severe pneumonia complicated by acute respiratory distress syndrome and reye syndrome (subbarao et al., ) . in november and december of the same year, concomittant with outbreaks of influenza h n among chickens in poultry markets and on farms in hong kong, additional cases of human h n infections were identified, five of which were fatal (yuen et al., ; chan ) . the outbreak was contained after the slaughtering of all . million chickens in hong kong. in response to the outbreak, influenza surveillance in poultry was intensified permitting early recognition of other outbreaks of avian influenza in and . no further human h n infections were reported until february , when two laboratory-confirmed cases and one probable case were identified in one family from hong kong . the daughter died of an undiagnosed respiratory infection while visiting fujian province in mainland china. upon their return to hong kong, the father and son developed severe respiratory illnesses of which the father died. h n virus was isolated from both patients. in december , an outbreak of highly pathogenic h n virus was identified among poultry in the republic of korea (lee et al., ) . subsequently, outbreaks by antigenically related viruses were reported among poultry in thailand, viet nam, japan, china, cambodia, laos, malaysia, and indonesia. the reason for this apparent simultaneous occurrence of h n outbreaks in many asian countries remains unclear. however, h n viruses have also been found in dead migratory birds, which may suggest a role of wild birds in the spread of h n viruses in the region .since , migratory birds indeed have also been responsible of spreading the virus to regions outside asia, including several countries in the middle east, europe and africa. human infections during the southeast asian outbreaks were first reported in early from viet nam and thailand, (hien et al., a; chotpitayasunondh et al., ) . since then, concurrent with the spread of the virus by migrating birds and consequent poultry outbreaks elsewhere, human h n infections have been reported in several other countries in asia (china, cambodia, indonesia), eurasia and europe (azerbaijan, iraq, turkey), and africa (egypt, djibouti). at the time of this writing (may ) more than human infections have been reported worldwide of which more than half were fatal (who, ) . it cannot be excluded and may even be likely that additional cases have gone unnoticed in affected countries due to a lack of clinical awaress, active surveillance, or diagnostic facilities (hien et al., b) . although many countries initially affected by poultry outbreaks in have been declared free of the virus, h n virus seems to have reached endemic levels in poultry and aquatic birds in several asian countries, despite attempts to contain the outbreak by extensive culling of poultry. this is also suggested by the establishment of multiple geographically distinct sublineages of h n influenza viruses in asia . continuing occurrences of bird-to-human transmissions increase the opportunity of the virus to adapt to humans and acquire the ability to spread between humans. in addition, continuing cocirculation of avian and human viruses in countries, where humans live in close proximity with poultry and pigs, increases the risk of reassortment between both in coinfected humans or other mammalian hosts, such as the pig. the isolation of h n viruses from pigs in china and indonesia is concerning in this respect . for all these reasons, the current developments in asia and other regions in the world seem to justify the global concern that, similar to and , a new pandemic influenza strain may emerge in the near future. at presentation, most cases of human h n infections were characterized by a severe influenza syndrome, clinically indistinguishable from severe human influenza, with symptoms of fever, cough, and shortness of breath, and radiological evidence of pneumonia (yuen et al., ; hien et al., a; chotpitayasunondh et al., ) . abnormalities on chest radiographs at presentation included extensive, usually bilateral infiltration, lobar collapse, focal consolidation, and air bronchograms (figure . ). radiological evidence of pulmonary damage could still be observed in surviving patients several months after the illness (t.t. hien, personal communication). beside respiratory symptoms, a large proportion of patients also complained of gastrointestinal symptoms such as diarrhea, vomiting, and abdominal pain, which are common in children with human influenza, but not in adults. in some cases, diarrhea was the only presenting symptom, preceding other clinical manifestations . unlike human infections with h or h viruses, conjunctivitis was not prominent in h n infected patients. the clinical course of the illness in severe cases was characterized by rapid development of severe bilateral pneumonia necessitating ventilatory support within days after onset. complications included acute respiratory distress syndrome, renal failure, and multiorgan failure. evidence that the clinical spectrum of human h n infections is not restricted to pulmonary symptoms was provided by a reported case of possible central nervous system involvement in a vietnamese boy who presented with diarrhea, followed by coma and death. influenza h n virus was isolated from throat, rectal, blood, and cerebrospinal fluid specimens, suggesting widely disseminated viral replication . his sister had died of a similar illness weeks earlier, but no diagnostic specimens were obtained. although highly virulent h n viruses have shown neurotropism in mammals such as mice and cats (lipatov et al., ; tanaka et al., ; keawcharoen et al., ) , these cases may be similarly rare as central nervous system manifestations associated with human influenza (morishima et al., ; sugaya, ) . genetic predisposition of the host to such manifestations may play a role. striking routine laboratory results in h n -infected patients, especially in severe cases, were an early onset of lymphopenia, with a pronounced inversion of the cd +/cd + ratio, thrombocytopenia, and increased levels of serum transaminases (yuen et al., ; hien et al., a; chotpitayasunondh et al., ) . high levels of cytokines and chemokines have been observed in several h n -infected patients, suggesting a role of immune-mediated pathology in the pathogenesis of h n infections (see section . . ) peiris et al., ) . this was supported by pathological examination in two patients who died during the outbreak in hong kong, which showed reactive hemophagocytosis as the most prominent feature . other findings included diffuse alveolar damage with interstitial fibrosis, hepatic central lobular necrosis, acute renal tubular necrosis, and lymphoid depletion. although the gastrointestinal, hepatic, renal, and hematologic manifestations could suggest wider tissue tropism, there was no evidence of viral replication in organs outside the respiratory tract . although many laboratory-confirmed h n infections were associated with severe, often fatal disease, milder cases have also been reported, especially during the outbreak in hong kong (yuen et al., ; chan ). an increasing number of milder cases also seemed to occur in viet nam, as the outbreak progressed in (who, ) . although increased clinical awareness and surveillance may account for such observations, progressive adaptation of the virus to humans is the dreaded alternative explanation. detailed monitoring of virus evolution during outbreaks is obviously important and may help to distinguish between both possibilities. the occurrence of mildly symptomatic and asymptomatic infections have also been suggested during the outbreak in hong kong by seroepidemiological studies in household members of h n infected patients and health care workers. in these studies, of exposed and of nonexposed health care workers were seropositive for h n -specific antibodies (bridges et al., ) . seroconversion was documented in two exposed nurses, one of whom reported a respiratory illness days after exposure to an h n -infected patient. more importantly than showing the occurrence of asymptomatic infections, these data indicated that nosocomial person-to-person transmission had occurred, albeit limited to a few cases. an additional case of possible human-tohuman transmission during the hong kong outbreak was suggested by h n -seropositivity in a household contact of a patient, who had no history of poultry exposure . seroepidemiological studies in health care workers involved in the care of h n -infected patients in thailand and viet nam in have not shown evidence of person-toperson transmission, despite the absence of adequate infection control measures in the vietnamese cohort at the time of study liem and lim, ; schultsz et al., ) . during the outbreak in thailand in , extensive epidemiological investigations have suggested person-to-person transmission from a child, who died of presumed h n infection, to her mother who had no history of exposure to poultry and had provided prolonged unprotected nursing care to her daughter . an aunt of the child may have been infected by the same route because her last exposure to poultry before infection had been days, considerably longer than the estimated incubation period of - days. there have been several similar family clusters of h n cases in other affected countries, which have all ignited concerns about the possibility of human-to-human transmission, but most of which could be explained by common exposure to poultry. although there has been no evidence of efficient transmission of influenza h n virus between humans to date, caution and detailed investigations obviously remain warranted in case of any cluster of infections, especially in view of the relatively rapid evolution h n viruses have exhibited in recent years. . . . . the evolution of h n viruses, in , an h n virus was isolated from geese during an outbreak in guangdong province in china (influenza a/goose/guangdong/ / [a/g/gd/ ]) (xu et al., ) . this virus proved to be the donor of the ha gene of the reassortant h n viruses causing the outbreak among poultry and humans in hong kong in . the internal genes of the hong kong h n viruses were closely related to those of an h n virus isolated from quail (see section . . ) (guan et al., ) . the origin of the na gene remains unclear but was notable for a -amino-acid deletion in the stalk region (subbarao et al., ) . such deletions may be associated with adaptation of influenza viruses to land-based poultry (matrosovich et al., ) . the ha gene contained multibasic sequences at the cleavage site, in accordance with its classification as a highly pathogenic strain (claas et al., ; matrosovich et al., ) . the role of other genes potentially involved in its pathogenicity is reviewed in section . . . after the eradication of the hong kong strain, the goose precursor viruses continued to circulate in geese in southeastern china (cauthen et al., ; webster et al., ) . through reassortment between this virus and other avian viruses, multiple antigenically similar genotypes, which were highly pathogenic in chickens but not in ducks, emerged and again were eradicated in hong kong in and . then, in late , h n strains isolated from wild migratory birds and resident waterfowl in two hong kong parks showed marked antigenic drift and exhibited high pathogenicity in ducks sturm-ramirez et al., ) . the latter property is rarely found in nature and had not been observed in strains isolated during previous years. an antigenically and molecularly similar virus caused the two confirmed human infections in early in a family from hong kong (see section . . . ) peiris et al., ) . h n influenza viruses isolated from healthy ducks in southern china between and were all antigenically similar to the precursor influenza a/g/gd/ virus . it is thought that these ducks played a central role in the generation of the virus responsible for the outbreaks in southeast asia since . detailed genetic analyses of h n strains isolated during the period - from poultry and humans in china, hong kong, indonesia, thailand, and viet nam demonstrated that a series of genetic reassortment events, all traceable to the a/g/gd/ -precursor virus, ultimately gave rise to a dominant h n genotype (genotype z) in chickens and ducks . this genotype is implicated in the human cases in hong kong in and the outbreaks among poultry and humans since . the evolution of h n viruses in recent years has been associated with increasing virulence and an expanding host range, which beside terrestrial poultry and wild birds also includes mammals. although all h n viruses isolated from ducks in china between and were highly pathogenic in chickens, an increasing level of pathogenicity was observed in mice with the progression of time: virus isolated in and were less pathogenic than those isolated in and . it has been suggested that the increasing ability to replicate in mammals has resulted from transmission between ducks and pigs the expanding host range is also illustrated by successful experimental infection of domestic cats and natural infections of cats, tigers and leopards with recent h n strains (keawcharoen et al., ; kuiken et al., ; songserm et al., ) . in summary, continued evolution of h n viruses since , involving multiple genetic reassortment events between a/g/gd/ -like viruses and other avian viruses and perhaps transmission between birds and pigs or other mammalian hosts, has resulted in a highly virulent genotype with an expanded host range that is causing widespread outbreaks among wild birds, poultry and humans affecting several regions in the world. although transmission between birds and humans at present still seems inefficient, as does transmission between humans, this may change when the virus is allowed to continue its evolution through adaptation and reassortment. in clinical trials, human influenza has been clinically diagnosed correctly in approximately two-thirds of adults with influenza-like symptoms, despite the lack of pathognomomic features (monto et al., ) . although virus isolation remains the gold standard of diagnosis and indispensable for virus characterization, rapid laboratory confirmation of suspected human influenza in routine diagnostic laboratories is usually performed by immunochromatographic or immunofluorescent detection of influenza virus antigens or by reverse transcriptase (rt)-pcr detection of viral nucleic acids in respiratory specimens. in addition, serological evidence of human influenza a virus infection can be obtained by commercially available elisa kits that detect antibodies to conserved viral antigens, such as the nucleoprotein. in the absence of cocirculating avian influenza strains in the human population, further subtyping of influenza viruses or detection of subtype-specific antibodies are usually not done by routine diagnostic laboratories but are restricted to reference laboratories involved in epidemiological analyses and planning of vaccine strains. however, in case of an outbreak of avian influenza, efforts to further subtype the virus (e.g., by subtype-specific rt-pcr methods) should be made by routine laboratories because immediate knowledge about the infecting influenza subtype is essential for infection control and timely epidemiological investigations. dependence on reference laboratories, which in the case of many southeast asian countries affected by avian influenza outbreaks are situated abroad, potentially results in unacceptable delays and hampers timely recognition of outbreaks and institution of adequate control measures (hien et al., b) . however, the reality is that diagnostic facilities in many affected countries are scarce and often not sufficiently equipped for virological diagnostics, let alone subtyping of influenza viruses. global efforts to improve diagnostic capacity in resource-poor countries may prove an important step toward the prevention and control of pandemic influenza (hien et al., b ). similar to human influenza viruses, avian viruses can be isolated in embryonated eggs or in cell culture, using permissive cells such as madin darby canine kidney (mdck) cells or rhesus monkey kidney (llc-mk ) cells. unlike human strains and avirulent avian strains and in accordance with their promiscuity for cellular proteases, highly pathogenic avian viruses do not require the addition of exogenous trypsine for efficient replication in cell culture. for safety purposes, the isolation of highly pathogenic avian influenza virus requires biosafety level laboratory facilities or higher. cytopathic effects in cell culture are nonspecific. initial identification of influenza a virus can be performed by immunofluorescence staining with monoclonal antibodies against the nucleoprotein. further ha and na subtyping is performed by subtype-specific rt-pcrs of culture supernatant or hemagglutination inhibition and neuraminidase inhibition assays using a panel of reference antisera against various subtypes. in human infections, avian influenza viruses have mostly been isolated from conjunctival swabs and respiratory specimens such as throat or nasal secretions or washings (yuen et al., ; fouchier et al., ; hien et al., a) . in one case of h n infection, virus was also isolated from serum, cerebrospinal fluid, and a rectal swab . detection of influenza a viral antigens in clinical specimens by direct immunofluorescence or by rapid immunochromatographic assays is widely used for diagnosis of human influenza because of their ability for rapid diagnosis. however, in patients with avian influenza, the usefulness of these assays seems limited due to low sensitivity, possibly because of lower viral loads than during human influenza (yuen et al., ; peiris et al., ) . in addition, some rapid antigen detection kits do not distnguish between influenza types a and b, and none of the currently available immunofluoresence and immunochromatographic assays distnguishes between influenza a subtypes. however, developments of h n -specific rapid antigen detection tests are ongoing . rt-pcr methods allow for sensitive and specific detection of viral nucleic acids and have shown to increase the diagnostic sensitivity for many viral pathogens when compared with culture or antigen detection methods. during the h n outbreaks in hong kong and southeast asia, rt-pcr methods for specific detection of h n viral nucleic acids proved valuable and seem to be the diagnostic methods of choice in case of an outbreak of avian influenza (yuen et al., ; hien et al., a; chotpitayasunondh et al., ) . especially when using real-time pcr technology, a reliable subtype-specific diagnostic result can be generated within a few hours after specimen collection. a disadvantage of rt-pcr methods is its proneness for contamination and the consequent risk of false-positive results, which should be minimized by proper precautions, including physical separation of laboratories for pcr preparation and amplification. in addition, the inclusion of an internal control in rt-pcr assays is highly desirable to monitor for false-negative results due to inefficient nucleic acid extraction, cdna synthesis, or amplification. during outbreaks of avian influenza, the detection of subtypespecific antibodies is particularly important for epidemiological investigations. hemagglutination inhibition (hi) assays are the gold standard for detection of antibodies against human influenza viruses. however, their usefulness for detection of antibodies against avian viruses in mammalian species, including humans, seems limited (hinshaw et al., ; beare and webster, ; kida et al., ) . several studies have shown a failure to detect hi antibodies against avian viruses in mammals, even in cases where infection was confirmed by virus isolation. possible reasons for this failure include poor immunogenicity of some avian viruses and lack of sensitivity to detect low-titered or less avid antibodies induced by avian viruses (hinshaw et al., ; lu et al., ; kida et al., ; rowe et al., ) . it has been demonstrated that hi testing with subunit ha, but not with intact virus, could detect antibodies against an avian h n virus (lu et al., ) . however, neutralizing antibodies against this virus could readily be detected with intact virus. a direct comparison of hi testing with a microneutralization assay in h n -infected persons from the hong kong outbreak indeed showed the latter to be more sensitive . although an indirect elisa assay using recombinant ha from h n / showed at least equal sensitivity as the microneutralization assay, the specificity in adult sera was inferior, most likely due to the presence of cross-reactive epitopes common to all has . based on these observations, neutralization assays are the methods of choice for detection of antibodies against avian viruses in humans. using these assays, it has been shown that the kinetics of the antibody response against h n virus in patients infected during the hong kong outbreak are similar to the primary response to human influenza viruses . neutralizing antibodies were generally detected or more days after the onset of symptoms, and titers equal to or higher than : were observed or more days after onset. using neutralization assays, antibodies against h n could be detected in a small number of blood donors from hong kong (peiris et al., ) . however, in two laboratory-confirmed h n -infected patients with conjunctivitis, no neutralizing antibodies could be detected in sera obtained more than days after onset of the illness . similarly, no hi antibodies could be detected in an h n -infected patient with conjunctivitis . although the reason for this apparent failure to mount an antibody response remains unclear, it has been suggested that this could be secondary to the highly localized nature of the infection in these cases . currently, two classes of drugs are available with antiviral activity against influenza viruses: inhibitors of the ion channel activity of the m membrane protein, amantadine and rimantadine; and inhibitors of the neuraminidase, oseltamivir and zanamivir. the therapeutic efficacy of amantadine in human influenza is unclear due to a paucity of reliable clinical studies, but reductions of fever or illness by day have been observed in adults and children (nicholson et al., ) . major disadvantages of amantadine include neurotoxicity and a rapid development of drug resistance during treatment. resistance is conferred by single nucleotide changes resulting in amino acid substitutions at positions , , , , or of the m protein. rates of resistance against amantadine in human influenza viruses has increased from less than . % in - to more than % in - . particularly high resistance frequencies of up to % were observed in viruses isolated in asia (bright et al., ) . rimantadine causes less neurological side effects but is not available in most parts of the world. although several h n -infected patients have been treated with amantadine during the h n outbreak in hong kong, the numbers were too small to draw any meaningful conclusions concerning its activity against this virus (yuen et al., ) . in vitro sensitivity testing of virus isolated from the first patient during this outbreak showed normal susceptibility to amantadine (subbarao et al., ) . strikingly, the sublineage of genotype z h n viruses prevalent in thailand, viet nam, cambodia and malaysia in invariably showed an amantadine-resistance conferring amino acid substitution at position of the m protein, while this mutation was mostly not present in sublineages of h n viruses isolated in other geographic regions puthavathana et al., ; cheung et al., ) . both oseltamivir and zanamivir have proven efficacy in the treatment of human influenza when started early during the course of illness and are particularly effective as seasonal or postexposure prohylaxis (nicholson et al., ) . zanamivir has poor oral availability and is therefore administered by inhalation, which has limited its use in the elderly and may induce bronchospasm. oseltamivir can be given orally. the development of drug resistance during treatment has been reported for both drugs and is associated with mutations in the active site of neuraminidase or in the hemagglutinin. the latter mutations decrease the affinity of ha for the cellular receptor, thereby obviating the need for neuraminidase to escape the cells. data on the efficacy of neuraminidase inhibitors in avian influenza virus infections are scarce. the h n strains implicated in the hong kong outbreak were susceptible in vitro to oseltamivir and zanamivir (leneva et al., ; govorkova et al., ) . oral oseltamivir and topical zanamivir also showed therapeutic and protective activities against hong kong h n isolates in murine animal models (gubareva et al., ; leneva et al., ) . recent murine studies suggest that, perhaps due to higher virulence, higher doses of oseltamivir and longer durations of treatment are necessary to achieve antiviral effects in mice against h n strains causing the southeast asian outbreak since , when compared with the hong kong h n strain (yen et al., ) . in vitro sensitivity testing of h n isolates during the outbreak of this virus in the netherlands showed normal susceptibility to zanamivir and oseltamivir . h n infection was detected in of persons who reportedly received prophylactic treatment with oseltamivir during that outbreak, compared with of persons who had not taken oseltamivir prophylaxis . oseltamivir treatment has been given to several patients infected with avian influenza viruses, including h n , h n , and h n subtypes, but no conclusions can be made concerning its efficacy. however, the timing of antiviral treatment may not have been optimal in many human cases of avian influenza so far. beneficial effects of antiviral treatment in human influenza are optimal when started within h after onset of the illness. during the h n outbreak in viet nam in , h n infected patients were admitted days or later after onset of symptoms (hien et al., a) . earlier recognition of avian influenza in humans may improve the efficacy of antiviral treatment. nevertheless, favourable virological responses associated with a beneficial clinical outcome have been reported in h n -injected patients despite late initiation of treatment . the emergence of drug-resistant h n variants during prophylaxis or treatment with oseltamivir has also been reported, and may be associated with clinical failure of treatment le et al., ) . treatment strategies which minimize the risk of resistance development, such as antiviral combination treatment, deserve attention. in addition, parenteral formulations of antiviral drugs may be desirable to guarantee systemic drug levels in h n patients with severe disease. a novel intravenously administered neuraminidase inhibitor, peramivir, is currently in clinical development. although several h n -infected patients have received steroids in addition to oseltamivir, the potential benefits of this need formal evaluation in clinical studies (hien et al., a) . considering the observed cytokine dysregulation in h n -infected animals and humans, a beneficial effect of immunomodulating agents could be hypothesized and perhaps requires further study. finally, neutralizing monoclonal antibodies have been shown effective in treating established influenza a virus infection in mice with severe combined immunodeficiency (palladino et al., ) . although mice are not men, this strategy deserves attention in the treatment of a severe illness such as influenza h n . birds infected with avian influenza excrete large amounts of virus in feces and other secretions, which contaminate the direct environment, such as dust, soil, water, cages, tools, and other fomites. avian influenza virus may remain infectious in soil, water, or contaminated equipment for weeks to months, depending on the temperature and humidity (i.e., longer in colder climates). illness in birds caused by highly pathogenic avian influenza viruses results in systemic replication and the presence of infectious virus in their eggs and many tissues and organs. transmission of avian influenza viruses between birds occurs directly or indirectly through contact with fecally contaminated aerosols, water, feed, and other materials. bird-to-human transmission likely occurs via the same route (i.e., direct contact with birds or contaminated fomites). most, but not all human infections with avian influenza viruses involved handling of affected poultry or direct exposure to live poultry in the week before onset of the illness (mounts et al., ; hien et al., a; koopmans et al., ) . case-control studies during the h n outbreak in hong kong identified visiting a stall or market selling live poultry during the week before the illness as a risk factor, whereas eating or preparing poultry products were not risk factors (mounts et al., ) . in cases in which no apparent direct exposure to poultry could be identified, contact with contaminated environment, such as water, has been suggested . of note, it has been shown that ducks infected by the currently circulating h n strain in southeast asia remain healthy but excrete large amounts of virus for prolonged periods of time (hulse-post et al., ) . because water in ponds and canals in which large flocks of ducks reside is widely used for bathing and drinking in rural areas of many southeast asian countries, it may not be unlikely that such water represents a source of transmission when contaminated by infected ducks. in fact, contact with contaminated water is regarded as the most important mode of transmission between aquatic birds. a limited number of possible human-to-human transmissions have been reported, which involved prolonged, close, and unprotected contact with infected patients koopmans et al., ; ungchusak et al., ) . similar to human influenza, droplet and contact transmission are probably the most effective means of transmission of avian influenza virus between humans, should the the virus acquire the ability for efficient spread, but airborne transmission remains a possibility. the occurrence of diarrhea in h n -infected patients, which may contain infectious virus, represents a potential nonrespiratory route of transmission that needs to be considered in infection control practices hien et al., a; . data concerning excretion patterns and periods of potential infectivity are lacking for human infections with avian influenza viruses. based on exposure histories, the incubation time for human h n -infections has been estimated at - days, but it is not known whether excretion of virus occurs during this time (yuen et al., ; hien et al., a) . based on the current (lack of) knowledge, infection control measures during contact with potentially infected birds or environment or with patients with suspected or confirmed infection should prevent contact, droplet, and airborne transmission. these measures include mask (preferably high-efficiency masks, with surgical masks as a second alternative), gown, face shield or goggles, and gloves. the efficacy of neuraminidase inhibitors as seasonal or postexposure prohylaxis against human influenza is high (nicholson et al., ) . offering prophylactic treatment to potentially exposed people in the setting of a poultry outbreak of avian influenza, as has been done during h outbreaks in the netherlands and canada tweed et al., ) , is rational but hardly feasible during the ongoing outbreak in asia and africa for logistical and financial reasons. postexposure prophylaxis to unprotected health care workers and close contacts of infected patients needs serious consideration. the potential use of specific monoclonal antibodies for prophylaxis warrants further investigation. eliminating the source of infection (i.e., infected birds) remains the most effective infection control measure. culling of all infected poultry has proved succesful during avian influenza outbreaks in hong kong, the netherlands, and canada (chan, ; koopmans et al., ; tweed et al., ) . however, considering the geographic extensiveness of the outbreak, the different farming practices in affected regions, and the occurence of infection in migratory birds, it is doubtful whether culling of poultry will be able to contain the outbreaks in the various regions. the bulk of human influenza vaccines are produced from inactivated viruses grown in embryonated eggs. vaccine production against highly pathogenic avian influenza viruses is complicated because of the requirement for high biosafety containment facilities and the difficulty, in some cases, to obtain high virus yields in embryonated eggs because of the virus' pathogenicity (stephenson et al., ; wood and robertson, ) . several other approaches have been used in an attempt to overcome these obstacles, including the use of reverse genetics techniques, generation of recombinant hemagglutinin, dna vaccination, and the use of related apathogenic h viruses with and without different adjuvants (nicholson et al., ; stephenson et al., ; webby et al., ; wood and robertson, ) . experimental h n vaccines in which important virulence determinants were altered using plasmid-based reverse genetics have shown protective efficacy to homologous and heterologous h strains in animal models and may prove an attractive approach takada et al., ; lipatov et al., b) . studies in humans using an h n vaccine developed from a apathogenic avian virus showed high rates of seroconversions to the vaccine strain and heterologous h n strains after doses, but only when the vaccine was given with the adjuvant mf . in animal models, baculovirus-derived recombinant h vaccines were immunogenic and protective, but results in humans were disappointing even when using high doses (crawford et al., ; treanor et al., ) . in a study using a subvirion influenza h n vaccine, neutralizing antibody responses were observed in approximately half of the subjects receiving the highest dose of the vaccine (two intramuscular injections of micrograms) (treanor et al., ) . h dna vaccines protected mice from infection by homologous, but not by heterologous h n viruses (kodihalli et al., ; epstein et al., ) . the increasing frequency of outbreaks with highly pathogenic avian influenza viruses among poultry and wild birds, and direct transmission of these viruses to humans, has ignited grave concerns about an imminent influenza pandemic. indeed, two of three prerequisites for a human pandemic have been met in the h n outbreaks since : the emergence of an antigenically novel strain to which the population has no immunity, and the transmission of this strain to humans in whom it can cause severe disease. to date, there fortunately is no evidence of efficient spread of h n virus between humans, but continued circulation of this strain, which now has reached levels of endemicity among poultry in several asian countries, increases the opportunity to adapt to humans through mutation or genetic reassortment in humans or intermediate mammalian hosts. as suggested by the "spanish flu" pandemic of , extremely high transmissibility is no prerequisite for a severe pandemic killing tens of millions of people, and as shown by the severe acute respiratory syndrome (sars) virus epidemic in , viruses can rapidly spread across the globe in the current age of intense global travel. as a consequence of all this, pandemic preparedness has become an increasingly important issue, and pandemic plans are being developed by an increasing number of countries worldwide. control measures based on case identification (e.g., contact tracing and quarantine) were essential for the control of sars. however, during an influenza epidemic, such measures may not be as effective because of short incubation periods and the potential infectivity before the onset of case-defining symptoms. much of the preparedness therefore will rely on clinical management and vaccination. mathematical modelling studies have suggested the possibility of containing an influenza pandemic at the source by antiviral prophylaxis and other preventive measures (ferguson et al., ; longini et al., ) . many developed countries are now stockpiling antiviral drugs for initial management of illness or prophylaxis during the first months of a pandemic, when vaccines are in development and not yet available. in case of an influenza pandemic, there will be limitations on the timeliness and availability of vaccines (stohr and esveld, ) . it has been estimated that it could take at least months for the first vaccine doses to be produced after identifying a pandemic strain. currently, global production capacity for influenza vaccines is insufficient for worldwide coverage in case of a pandemic, especially because vaccination for the novel influenza strain likely requires two doses, and interruption of annual production of the human influenza vaccine is undesirable (schwartz and gellin, ) . in response to the pandemic threat by the h n outbreak in southeast asia, plans have been made to stockpile candidate h n vaccines based on the currently circulating strain. however, there is no certainty whether the next pandemic will indeed be caused by h n virus, and if so, whether antigenic drift will not have rendered the stockpiled vaccine less effective by the time pandemic spread occurs. in the latter event, such vaccines may still mitigate the illness, which is beneficial for vaccinated people but may also carry a risk of prolonged excretion and increased spread of the virus. similar worries exist when poultry would be vaccinated with a suboptimal vaccines. in case of an influenza pandemic, all possibilities for rapid production of vaccines, as well as potential methods to reduce doses without affecting immunogenicity should be considered. this would require the use of alternative, currently not officially approved methods for vaccine production, such as reverse genetics techniques and cell culture-based vaccine production, and the use of alternative adjuvants that may enable dose reduction (webby and webster, ; stephenson et al., ; wood and robertson, ; schwartz and gellin, ) . in addition, vaccine doses may be spared by alternative administration routes. it has been shown that intradermal, instead of intramuscular vaccination for human influenza may require less antigen by recruiting efficient antigen-presenting cells present in the dermis (belshe et al., ; kenney et al., ) . notwithstanding the importance of current efforts to prepare for a possible h n pandemic, more structural and longer term global efforts are needed to allow for early recognition of emerging novel influenza viruses in the future. in , a who global agenda for influenza surveillance and control has been adopted, of which the main objectives are to strengthen surveillance, improve knowledge of the disease burden, increase vaccine use, and accelerate pandemic preparedness (stohr, ) . it is essential that these objectives are increasingly focused on the southeast asian region, which has been the source of previous pandemics and is the epicenter of the current pandemic threat. however, many southeast asian countries currently lack the expertise, financial means, and infrastructure for human and animal surveillance. global investments to improve public health care infrastructures and laboratory facilities and to transfer clinical, epidemiological, and technical knowledge to these countries are much needed (hien et al., b) . the window of opportunity in the era of global travel is narrow. local capacity, and less dependence on foreign laboratories and expertise, will allow for earlier recognition and quicker responses to epidemics. in addition, local availability of clinical, scientific, and laboratory capacity facilitates and expedites clinical, virological, and epidemiological analyses needed to optimize outbreak control, infection control, and clinical managment and guarantees the timely availability of virus strains for monitoring virus evolution and planning of vaccines by reference laboratories. in response to the h n outbreak in hong kong, influenza surveillance in poultry was intensified, which permitted early recognition of outbreaks by other avian influenza strains and timely interventions and has helped to keep hong kong free of h n influenza despite the outbreak of this virus in many other countries in the region. the hong kong response may serve as a model, but wider implementation of this approach will require global efforts. a single gene determines the host range of influenza virus atypical avian influenza (h n ) seroprevalence of anti-h antibody among thai health care workers after exposure to avian influenza (h n ) in a tertiary care center antigenic mapping of an avian h influenza virus haemagglutinin and interrelationships of h viruses from humans, pigs and birds sequence of the pandemic influenza virus nonstructural gene (ns) segment and characterization of recombinant viruses bearing the ns genes the n neuraminidase of human influenza virus has acquired a substrate specificity complementary to the hemagglutinin receptor specificity evolution of the h influenza virus hemagglutinin from human and nonhuman hosts replication of avian influenza viruses in humans serum antibody responses after intradermal vaccination against influenza proteolytic cleavage of influenza virus hemagglutinins: primary structure of the connecting peptide between ha and ha determines proteolytic cleavability and pathogenicity of avian influenza viruses risk of influenza a (h n ) infection among poultry workers incidence of adamantane resistance among influenza a (h n ) viruses isolated worldwide from fowl plague virus from man continued circulation in china of highly pathogenic avian influenza viruses encoding the hemagglutinin gene associated with the h n outbreak in poultry and humans proinflammatory cytokine responses induced by influenza a (h n ) viruses to primaty human alveolar and bronchial epithelial cells outbreak of avian influenza a(h n ) virus infection in hong kong in the evolution of h n influenza viruses in ducks in southern china world health organization global influenza program surveillance network. evolution of h n avian influenza viruses in asia structure of the hemagglutinin precursor cleavage site, a determinant of influenza pathogenicity and the origin of the labile conformation induction of proinflammatory cytokines in human macrophages by influenza a (h n ) viruses: a mechanism for the unusual severity of human disease distribution of amantadine-resistant h n avian influenza variants in asia continuing evolution of h n influenza viruses in southeastern china human disease from influenza a (h n ) human influenza a h n virus related to a highly pathogenic avian influenza virus receptor specificity in human, avian, and equine h and h influenza virus isolates influenza virus strains selectively recognize sialyloligosaccharides on human respiratory epithelium; the role of the host cell in selection of hemagglutinin receptor specificity baculovirus-derived hemagglutinin vaccines protect against lethal influenza infections by avian h and h subtypes fatal avian influenza a (h n ) in a child presenting with diarrhea followed by coma oseltamivir resistance during treatment of influenza a (h n ) infection comparative study of fowl plague virus and a virus isolated from man glycosylation affects cleavage of an h n influenza virus hemagglutinin and regulates virulence characterization of a spontaneously immortalized cell line (ioba-nhc) from normal human conjunctiva influenza. test kit error is wake-up call for -year-old foe dna vaccine expressing conserved influenza virus proteins protective against h n challenge infection in mice strategies for containing an emerging influenza pandemic in southeast asia avian influenza a virus (h n ) associated with human conjunctivitis and a fatal case of acute respiratory distress syndrome characterization of a novel influenza a virus hemagglutinin subtype (h ) obtained from black-headed gulls the viral polymerase mediates adaptation of an avian influenza virus to a mammalian host specification of receptor-binding phenotypes of influenza virus isolates from different hosts using synthetic sialylglycopolymers: nonegg-adapted human h and h influenza a and influenza b viruses share a common high binding affinity for ′-sialyl(n-acetyllactosamine) the structure and receptor binding properties of the influenza hemagglutinin inhibition of interferon-mediated antiviral responses by influenza a viruses and other negative-strand rna viruses mechanisms of inhibition of the host interferon alpha/beta-mediated antiviral responses by viruses understanding influenza virus pathogenicity cellular transcriptional profiling in influenza a virus-infected lung epithelial cells: the role of the nonstructural ns protein in the evasion of the host innate defense and its potential contribution to pandemic influenza comparison of efficacies of rwj- , zanamivir, and oseltamivir against h n , h n , and other avian influenza viruses molecular characterization of h n influenza viruses: were they the donors of the "internal" genes of h n viruses in hong kong? h n influenza viruses possessing h n -like internal genomes continue to circulate in poultry in southeastern china emergence of multiple genotypes of h n avian influenza viruses in hong kong sar h n influenza: a protean pandemic threat characterization of influenza a/hongkong/ / (h n ) virus in a mouse model and protective effect of zanamivir on h n infection in mice characterization of the pathogenicity of members of the newly established h n influenza virus lineages in asia molecular basis for high virulence of hong kong h n influenza a viruses avian influenza a (h n ) in patients in vietnam avian influenza-challenge to global health care structures replication of avian influenza a viruses in mammals altered tissue tropism of human-avian reassortant influenza viruses novel avian influenza h n strain outbreak reverse genetics provides direct evidence for a correlation of hemagglutinin cleavability and virulence of an avian influenza a virus role of domestic ducks in the propagation and biological evolution of highly pathogenic h n influenza viruses in asia molecular basis for the generation in pigs of influenza a viruses with pandemic potential antibody response in individuals infected with avian influenza a (h n ) viruses and detection of anti-h antibody among household and social contacts molecular mechanism of acquisition of virulence in influenza virus in nature interplay between carbohydrate in the stalk and the length of the connecting peptide determines the cleavability of influenza virus hemagglutinin avian-to-human transmission of the pb gene of influenza a viruses in the and pandemics avian influenza h n in tigers and leopards dose sparing with intradermal injection of influenza vaccine antigenic and genetic conservation of h influenza virus in wild ducks potential for transmission of avian influenza viruses to pigs host cell proteases controlling virus pathogenicity enhanced virulence of influenza a viruses with the haemagglutinin of the pandemic virus dna vaccine encoding hemagglutinin provides protective immunity against h n influenza virus infection in mice transmission of h n avian influenza a virus to human beings during a large outbreak in commercial poultry farms in the netherlands intracellular warfare between human influenza viruses and human cells: the roles of the viral ns protein avian h n influenza in cats avian influenza virus isolated from a woman with conjunctivitis avian flu: isolation of drug-resistant h n virus characterization of highly pathogenic h n avian influenza a viruses isolated from south korea the neuraminidase inhibitor gs (oseltamivir phosphate) is efficacious against a/hong kong/ / (h n ) and a/hong kong/ / (h n ) influenza viruses efficacy of zanamivir against avian influenza a viruses that possess genes encoding h n internal proteins and are pathogenic in mammals genesis of a highly pathogenic and potentially pandemic h n influenza virus in eastern asia recombinant influenza a virus vaccines for the pathogenic human a/hong kong/ (h n ) viruses lack of h n avian influenza transmission to hospital employees avian-to-human transmission of h n subtype influenza a viruses: relationship between h n and h n human isolates neurovirulence in mice of h n influenza virus genotypes isolated from hong kong poultry in influenza: emergence and control pathogenesis of hong kong h n influenza virus ns gene reassortants in mice: the role of cytokines and b-and t-cell responses efficacy of h influenza vaccines produced by reverse genetics in a lethal mouse model genetic conservation of hemagglutinin gene of h influenza virus in chicken population in mainland china containing pandemic influenza at the source failure to detect hemagglutination-inhibiting antibodies with intact avian influenza virions avian influenza a viruses differ from human viruses by recognition of sialyloligosaccharides and gangliosides and by a higher conservation of the ha receptor-binding site the surface glycoproteins of h influenza viruses isolated from humans, chickens, and wild aquatic birds have distinguishable properties h n influenza a viruses from poultry in asia have human virus-like receptor specificity human and avian influenza viruses target different cell types in cultures of human airway epithelium transmissibility of pandemic influenza clinical signs and symptoms predicting influenza infection encephalitis and encephalopathy associated with an influenza epidemic in japan case-control study of risk factors for avian influenza a (h n ) disease, hong kong mutations in the hemagglutinin receptorbinding site can change the biological properties of an influenza virus recent human influenza a (h n ) viruses are closely related genetically to strains isolated in human influenza virus hemagglutinin with high sensitivity to proteolytic activation avian influenza and sialic acid receptors: more than meets the eye? nonhomologous recombination between the hemagglutinin gene and the nucleoprotein gene of an influenza virus influenza a pandemics of the th century with special reference to : virology, pathology and epidemiology virus-neutralizing antibodies of immunoglobulin g (igg) but not of igm or iga isotypes can cure influenza virus pneumonia in scid mice functional anatomy of human lacrimal duct epithelium human infection with influenza h n cocirculation of avian h n and contemporary "human" h n influenza a viruses in pigs in southeastern china: potential for genetic reassortment? re-emergence of fatal human influenza a subtype h n disease molecular characterization of the complete genome of human influenza h n virus isolates from thailand origin and evolution of the "spanish" influenza virus hemagglutinin gene evidence of an absence: the genetic origins of the pandemic influenza virus pathogenesis of influenza a (h n ) virus infection in a primate model receptor determinants of human and animal influenza virus isolates: differences in receptor specificity of the h hemagglutinin based on species of origin single amino acid substitutions in influenza haemagglutinin change receptor binding specificity receptor binding properties of human and animal h influenza virus isolates detection of antibody to avian influenza a (h n ) virus in human serum by using a combination of serologic assays the polymerase complex genes contribute to the high virulence of the human h ni influenza virus isolate a/vietnam/ / host range recombinants of fowl plague (influenza a) virus genetic relatedness between the new epidemic strains (h n ) of influenza and human influenza strains isolated between and (h n ) on the origin of the human influenza virus subtypes h n and h n avian influenza h n and health care workers vaccination strategies for an influenza pandemic survey of the hemagglutinin (ha) cleavage site sequence of h and h avian influenza viruses: amino acid sequence at the ha cleavage site as a marker of pathogenicity potential tumor necrosis factor alpha exerts powerful anti-influenza virus effects in lung epithelial cells lethal h n influenza viruses escape host antiviral cytokine responses the ns gene of h n influenza viruses circumvents the host anti-viral cytokine responses avian flu: influenza virus receptors in the human airway pb amino acid at position affects replicative efficiency, but not cell tropism, of hong kong h n influenza a viruses in mice characterization of avian h n influenza viruses from poultry in hong kong the avian influenza virus nucleoprotein gene and a specific constellation of avian and human virus polymerase genes each specify attenuation of avian-human influenza a/pintail/ reassortant viruses for monkeys avian influenza h n in naturally infected domestic cat role of hemagglutinin cleavage for the pathogenicity of influenza virus confronting the avian influenza threat: vaccine development for a potential pandemic cross-reactivity to highly pathogenic avian influenza h n viruses after vaccination with nonadjuvanted and mf -adjuvanted influenza a/duck/singapore/ (h n ) vaccine: a potential priming strategy structure of the uncleaved human h hemagglutinin from the extinct influenza virus the global agenda on influenza surveillance and control public health. will vaccines be available for the next influenza pandemic? reemerging h n influenza viruses in hong kong in are highly pathogenic to ducks recombination resulting in virulence shift in avian influenza outbreak a single amino acid in the pb gene of influenza a virus is a determinant of host range characterization of an avian influenza a (h n ) virus isolated from a child with a fatal respiratory illness influenza-associated encephalopathy in japan single-amino-acid substitution in an antigenic site of influenza virus hemagglutinin can alter the specificity of binding to cell membrane-associated gangliosides avirulent avian influenza virus as a vaccine strain against a potential human pandemic neurotropism of the hong kong h n influenza virus in mice initial genetic characterization of the characterization of the influenza virus polymerase genes a case report of fowl plague keratoconjunctivitis pathology of fatal human infection associated with avian influenza a h n virus safety and immunogenicity of an inactivated subvirion influenza a (h n ) vaccine safety and immunogenicity of a recombinant hemagglutinin vaccine for h influenza in humans human illness from avian influenza h n , british columbia probable person-to-person transmission of avian influenza a (h n ) h n virus attachment to lower respiratory tract importance of conserved amino acids at the cleavage site of the haemagglutinin of a virulent avian influenza a virus are we ready for pandemic influenza? responsiveness to a pandemic alert: use of reverse genetics for rapid development of influenza vaccines intestinal influenza: replication and characterization of influenza viruses in ducks conjunctivitis in human beings caused by influenza a virus of seals molecular mechanisms of variation in influenza viruses influenza virus a pathogenicity: the pivotal role of hemagglutinin evolution and ecology of influenza a viruses virology. a molecular whodunit characterization of h n influenza viruses that continue to circulate in geese in southeastern structure of the influenza virus haemagglutinin complexed with its receptor, sialic acid cumulative number of confirmed human cases of avian influenza a/(h n ) reported to who structure of the haemagglutinin membrane glycoprotein of influenza virus at a resolution from lethal virus to life-saving vaccine: developing inactivated vaccines for pandemic influenza genetic characterization of the pathogenic influenza a/goose/guangdong/ / (h n ) virus: similarity of its hemagglutinin gene to those of h n viruses from the outbreaks in hong kong latex agglutination test for monitoring antibodies to avian influenza virus subtype h n virulence may determine the necessary duration and dosage of oseltamivir treatment for highly pathogenic a/vietnam/ / (h n ) influenza virus in mice clinical features and rapid viral diagnosis of human disease associated with avian influenza a h n virus pathogenesis of avian influenza a (h n ) viruses in ferrets key: cord- -pmzdovna authors: pennington, hugh title: politics, media and microbiologists date: journal: nat rev microbiol doi: . /nrmicro sha: doc_id: cord_uid: pmzdovna severe acute respiratory syndrome (sars) took everybody by surprise. its emergence was one of the most significant microbiological events of . it challenged microbiologists to identify the aetiological agent and satisfy koch's postulates — in so far as they ever can be met for a virus — in real time. not only were the patients' respiratory secretions and the agents grown in cultured cells put under the microscope, but so were the actions of politicians. what lessons can we learn from sars? acquired , and of the , sars infections in hong kong, ( %) were in healthcare workers - of whom were hospital staff who were infected while on duty . a low degree of transmissibility relative to other viruses is not the only property of the sars virus that was an important factor in the success of the response to the outbreak. the ease of propagation and identification of sars by well-established, standard virological methods were also of significance. the causative virus was grown without particular difficulty or problems with detection in readily available standard cell-culture systems. within a month of the identification of sars as a new clinical entity of uncertain aetiology -in late february in hanoi, vietnam -the virus had been grown in several laboratories. researchers at the university of hong kong cultured the virus using foetal rhesus monkey kidney cells challenged with material from an open lung biopsy from a -year-old male hong kong resident, and a nasopharyngeal aspirate from a -year-old woman. researchers at the bernhard nocht institue for tropical medicine, hamburg used vero cells inoculated with sputum from a -year-old male physician who had fallen ill in new york, after travelling from singapore where he had treated a patient. finally, at the centers for disease control and prevention (cdc), atlanta , researchers cultured the virus in vero cells inoculated with oropharyngeal samples from a -year-old male physician working in vietnam, sputum from a -year-old male, a kidney sample from a -year-old male and oropharyngeal washings from an adult vietnamese patient. in hong kong and atlanta the results of thinsection and negative-staining electron microscopy showed unequivocally that the cytopathic effect was being caused by a coronavirus. in all three laboratories, reverse transcription pcr and comparison with known coronavirus sequences revealed the same sequence identity; this work also showed that the sars virus was new, because its sequences were only distantly related to those from the wide range of previously sequenced coronaviruses that infect humans, dogs, cats, pigs, bovines, rats, mice, turkeys and chickens. louis pasteur said that "chance favours the prepared mind". the relevance of this explanation of scientific success to the sars virus, and in particular to the rapid initiation of collaborative work to understand and control it, is very clear. influenza had prepared the way. ever since the - influenza pandemic -which killed many millions, and was the low r value for sars indicates that controlling the spread of infection should be easier to achieve than for many other respiratory viruses. the only other virus spread by the respiratory route with an r value approaching that of sars is smallpox. for isolated pre-twentieth century populations with negligible immunity, gani and leach estimated the r value for smallpox to be . - . and, for importations into europe between and , to be about . for community-acquired disease. although an r value of this magnitude means that without control measures an outbreak would grow exponentially, in the case of smallpox outbreaks it was always possible to rapidly reduce the value of r during the progress of an outbreak. maintaining the r value below prevented the development of secondary cases; it was achieved by locating and isolating cases, and creating a ring of immune individuals around the outbreak by vaccination. outbreaks lasted only for weeks, with case numbers rarely exceeding double figures; more than three-quarters of outbreaks ended with the generation that was infected immediately after the detection of infection. r is a function of k,b and d ; where k is the number of contacts each infectious individual has per unit time; b is the probability of transmission per contact between an infectious case and a susceptible person; and d is the mean duration of infectiousness . in the case of infectious patients in hospital, their physical proximity to other patients and regular -often close and prolonged -contact with medical staff and nurses means that k and b will be greater than in the community or in domestic settings, particularly if transmission is only effective over short distances -centimetres rather than metres. this was the case for both sars and smallpox, and nosocomial transmission was indeed a characteristic feature. in outbreaks of variola major in europe between - , reviewed by mack , transmissions in hospital settings far outnumber those in any other category. of the cases, ( . %) contracted the disease in hospital, and cases ( . %) were in staff. in singapore, ( %) sars cases were nosocomially severe acute respiratory syndrome (sars) took everybody by surprise. its emergence was one of the most significant microbiological events of . it challenged microbiologists to identify the aetiological agent and satisfy koch's postulates -in so far as they ever can be met for a virus -in real time. not only were the patients' respiratory secretions and the agents grown in cultured cells put under the microscope, but so were the actions of politicians. what lessons can we learn from sars? the common cry uttered after crises is that 'lessons must be learned' . what lessons does sars teach? the crisis is over, at least for the time being, but how certain can we be that the german philosopher hegel was wrong when he said "what experience and history teach is this -that people and governments have never learned anything from history, or acted upon principles deduced from it"? before attempting to answer these questions using sars as an appropriate example, it is necessary to consider the sars virus itself and ask another question. how severe a test did sars pose? were we lucky? the answer is 'yes, we were' . this is qualified by the number of deaths that it caused; however, it is due, at least in part, to the properties of the virus. most important is the low r value -the basic reproductive number -for the sars virus, which represents the number of secondary infectious cases that are generated by an average infectious case in a susceptible population. the r value predicts the likelihood that an infectious agent will start an outbreak, the amount of transmission that can be expected in the absence of control measures and the ability of these control measures to reduce spread. studies on the sars outbreak in hong kong -after the exclusion of two 'superspread' events where special circumstances allowed index cases to infect many individuals (at the prince of wales hospital and at the amoy gardens estate) -gave an estimated r value of . . this is much lower than for any other virus that is spread by the respiratory route; r values for such infections in england and wales have been estimated to be - for measles, - for chickenpox, - for measles and - for rubella . national influenza centres in countries also had an extremely important role . reports in early february from guandong province, china, of cases and five deaths owing to an atypical pneumonia of unknown aetiology, coupled with the isolation of an avian influenza virus a subtype h n from two members of a family that had visited fujian province, china, in january, caused the activation of the pandemic plan. from analyses of samples taken from vietnam, singapore and hong kong, laboratories in the network ruled out the possibility of infection by any of the known influenza virus strains or other established causes of pneumonia, and concluded that sars was new. on march , the who issued emergency travel advice and, using the influenza network as a model, set up a network of scientists from laboratories around the world to identify the causative agent and develop diagnostic tests. laboratories were chosen owing to their experience in detecting a wide range of microorganisms, a history of collaboration in international investigations coordinated by the who, their technical capacity to fulfil koch's postulates and their access to sars samples. rules governing the confidentiality of data were set -shared data and information would only be used to advance the project in a collaborative way, data would only be shared outside the network with the approval of the originating laboratory, and caused by a virus of subtype h n -the possibility of the emergence of a virus strain capable of causing a similar event has, of necessity, been contemplated. the world health organization (who) initiated its international cooperation coordination programme in . pandemics with significantly lower mortalities occurred in (asian flu, subtype h n ), (hong kong flu, subtype h n ) and (russian flu, subtype h n ) (table ). although none have occurred since, the influenza outbreak that occurred in hong kong in , although local and small in case numbers, had such a high mortality rate in confirmed cases that it stimulated a review of pandemic response policies both in hong kong and internationally. it meant that the hong kong department of health, hospital authority and laboratory surveillance facility , and the who, were particularly well prepared to respond to the sars outbreak. in march , an outbreak of avian influenza caused by the a virus subtype h n killed several thousand chickens in three rural hong kong chicken farms. in may , a -year-old boy in hong kong contracted an influenza-like illness and died days later from reyes' syndrome -a paediatric complication that is associated with salicylate medication, which he had received. the virus strain resisted characterization with the available reagents; by august, detailed study in the netherlands and the united states had revealed that the virus was closely related to the avian strains that were prevalent in march. in november, human cases caused by this virus began to occur; by late december, there had been cases, of which five were fatal. contact with chickens had occurred in all confirmed cases. on december , the slaughter of all chickens in hong kong (a total of . million) began, their import was stopped and the outbreak ceased. in , a group of influenza specialists reviewed the responses to the outbreak and drew several lessons from them . some were influenza-specific, but others had wider relevance. regarding the actions that were taken in response to the outbreak, they reported that, at the time the outbreak started, the who was developing formal guidelines for addressing pandemic situations. these guidelines were revised after the hong kong influenza epidemic to include two strategic steps that were important in the outbreakrisk assessment (data collection and data evaluation) and risk management (continuously considering and reviewing the stages of a response, defining the risks and benefits, and making recommendations for the next steps to be followed). these principles underpinned the who response to sars. the who global influenza surveillance network of four collaborating centres (in atlanta, london, melbourne and tokyo) and committee was charged with the identification of lessons to be learned and with making recommendations for future epidemics. they focused on seven principles: a strengthened epidemiology capacity, systems for early detection and reporting, contingency planning, clear command and control structures, integrated responses, a surge capacity and transparency and effective communication. although it is impossible to disagree with these principles and their importance in outbreak control, a striking feature of the page report is that, with the exception of a box describing the isolation of the virus in hong kong entitled 'ground-breaking discovery' early in the report, there is little comment, favourable or unfavourable, about virology, virology laboratories or virologists. it could be said that this might be a reflection of the backgrounds and interests of the committee that generated the report -the two co-chairs (both from the united kingdom) were experts in hospital management and administration and in public health, respectively. but it is very probable that it reflects another problem -the lack of regard that is paid to the importance of microbiology in the response to microbiological threats to public health. reforming and improving healthservice administrative structures and information systems, and planning for unexpected rises in the number of contagious patients are all necessary, but by themselves they are insufficient. the flaw in hegel's aphorism about lessons from history is that microorganisms evolve in real time; learning lessons from past failures (and successes) will be insufficient because evolution throws up new challenges. in their review , maclehose, mckee and weinberg state that "one of the greatest challenges facing surveillance systems is awareness of the unexpected, recognizing when things seem not quite right. nipah virus was thought to be japanese b encephalitis, west nile virus in new york was thought to be st louis encephalitis, and prions were thought not to cross species barriers. focusing surveillance systems on the diseases of today fails to address the challenges of an uncertain future". we were lucky with sars due to the existence of a network of laboratories that were looking for new influenza viruses and which were linked by the mature surveillance network run by the who. other microbiological networks also exist. for food-borne pathogens there are, for example, pulse net in the united states (which uses standardized pulsed-field gel electrophoresis (pfge) protocols to generate and compare profiles of escherichia coli o , salmonella spp. and listeria monocytogenes), and enternet more than £ billion. the conclusions of the 'lessons to be learned inquiry' regarding the role of british virologists before and during the outbreak speak for themselves. the report states that, although the pirbright laboratory is the world reference laboratory and holds data on reported outbreaks throughout the world, "there is no coherent assessment of the full range of work undertaken by pirbright in relation to the national surveillance and control strategies" and "the service arrangements in place in covered the processing of samples a year…but contained no procedure for increasing the level of provision in an emergency". in addition, "the laboratory was not consulted when the fmd contingency plans were drawn up". the same failure to consult and use scientific expertise was evident in the handling of bovine spongiform encephalopathy (bse) -politics came before science. not long after the first occurrence of bse, an attempt to describe a case in the scientific literature was firmly quashed by the head of the veterinary investigation service of england and wales owing to "possible effects on exports and the political implications" . the phillips inquiry into bse and variant creutzfeldt-jacob disease (cjd) reported the lessons that had been learned; the largest number of which addressed one topic -the improved use of scientific advisory committees. their failure to use the full range of expertise available -even within the united kingdom -contrasts sharply with the inclusive approach adopted by the who in the case of the sars epidemic. the united kingdom was lucky with sars as there were no reported outbreaks. however, the situation was very different in hong kong, which had , cases and deaths. an expert review committee appointed by the government of the hong kong special administrative region reported its findings in october (ref. ). among other things, the samples would be regularly exchanged. there were daily teleconferences and a secure who website. on april , the participating laboratories collectively announced the conclusive identification of a new coronavirus as the causative agent. the who had performed well . owing to its low r value and ease of cultivation, the challenge that sars posed to the who was less difficult than it might have been. however, not everything was straightforward; for laboratories, epidemiologists and international organizations to react they must be told that there is a problem. the reaction to sars was delayed because initially it was unclear that there was a problem. the first cases of sars probably occurred in guangdong province, china, in november . on january , the health authority in guangdong province produced an expert report on the outbreak. many of the conclusions that the health authority reached would have been of significant use to policy makers elsewhere, but circulation of this expert report was limited. neither the who nor the hong kong authorities received a copy. whether an early reversal of the denial of sars by the chinese authorities during the early part of the epidemic would have had a significant effect on later events can only be a matter for speculation. however, the who was not able to investigate the situation in china until april , by which time sars had spread worldwide. a key factor in this spread had been the overnight stay in room of the metropole hotel, hong kong, of a professor from guangzhou in guangdong, which triggered outbreaks in hong kong, singapore, canada and vietnam. the lesson for microbiologists is a stark one -they operate in a political environment, and it can be unhelpful. other examples of the poor handling of infections by political systems are, unfortunately, not hard to find. there is a tradition in the united kingdom of responding to disasters by holding rigorous inquiries afterwards, which are expected to leave the public feeling "confident that a searching investigation has been held, that nothing has been swept under the carpet and that no punches have been pulled" . although this is good, the pity is that the need for such inquiries seems to recur far too often. in , the united kingdom suffered a serious outbreak of foot and mouth disease (fmd). millions of animals were slaughtered, and the overall costs totalled "the lesson for microbiologists is a stark one -they operate in a political environment, and it can be unhelpful." (which uses phenotypic data for typing), salmgene and pulsenet europe (both of which use pfge) in europe. the european commission has proposed the creation of a european centre for disease control and prevention to standardize surveillance methods, ensure data compatability, provide scientific assessments, technical support, information to officials and to the public, and to assume responsibility for existing networks and early warning and response systems. however, it is proposed that it will only have a staff of . the european health commissioner david byrne explained that "it will be a hub, an intelligence centre. the core is already in place". in this way it will be utterly reliant on national laboratories, national microbiologists and national infrastructures. is this 'core' up to the job? consider the united kingdom. its core is at least as effective as that of any other large european country. in universities, for example, it has many microbiologists of international rank . however, recent inquiries have identified serious problems. the recent report of the house of lords select committee on science and technology, 'fighting infection' , concluded that the infectious disease services in england that are "expected to protect the population from both common and more unusual infections are under-resourced and over-stretched…there is not enough surge capacity". the report went on to predict that "without improvements we fear that this country will suffer from major epidemics". the academy of medical sciences inquiry into 'academic medical bacteriology in the twenty-first century' focused on research. the inquiry concluded that although bacteriology has recently undergone a transformation with the introduction of several new techniques, "medical microbiology departments in the united kingdom, with a few exceptions, are in a state of torpor…". so microbiologists need to get their act together, and it will not do to rely on the bursts of funding and political approval that result from the panic engendered by disease outbreaks. hegel was right; history tells us that this kind of support is short-lived. sars proves the point. in july , the who declared the world to be free of sars, and in august , klaus stöhr, its sars research coordinator, stepped down and returned to influenza work owing to a lack of money . the ability to respond rapidly to new pathogens is not cheap. the next pathogen might have a high r value and be as elusive as a prion. the past tells us to be prepared. european budgets pale into insignificance compared with the $ . billion of the us cdc. obviously, european microbiologists have lessons to learn about getting political support! but funding is not the whole answer. the united kingdom, for example, has plenty of microbiological talent. recent experiences with bse and fmd indicate the need for big improvements in how policy makers get scientific advice. this problem persists. doctors, veterinarians, civil servants, politicians and scientists must come out of their boxes, learn to speak their different languages and communicate more effectively. if they fail, sooner or later there will be a heavy price to pay. evolution says so. coronavirus as a possible cause of severe acute respiratory syndrome identification of a novel coronavirus in patients with severe acute respiratory syndrome a novel coronavirus associated with severe acute respiratory syndrome up close and personal with sars the next influenza pandemic: lessons from hong kong world health organization multicentre collaborative network for severe acute respiratory syndrome diagnosis. a multicentre collaboration to investigate the cause of severe acute respiratory syndrome report of the uk academy of medical sciences working group on sars the merchant shipping act formal investigations . (the stationery office report of the 'lessons to be learned' inquiry report when food kills responding to the challenge of communicable disease in europe the national molecular subtyping network for foodborne disease surveillance european equivalent of us centers for disease control proposed research assessment exercise: the outcome house of lords select committee on science and technology session - fourth report. fighting infection academic medical bacteriology in the twenty-first century search for sars origins stalls transmission dynamics of the etiological agent of sars in hong kong: impact of public health interventions infectious diseases of humans transmission potential of smallpox in contemporary populations transmission dynamics and control of severe acute respiratory syndrome smallpox in europe, - severe acute respiratory syndrome: lessons from singapore sars in hong kong: from experience to action the author declares that he has no competing financial interests. http://www.bt.cdc.gov centers for disease control and prevention: http://www.cdc.gov/ pulse net: http://www.cdc.gov/pulsenet/ society for general microbiology: http://www.sgm.ac.uk access to this interactive links box is free online. key: cord- -lca xum authors: voelkner, nadine title: riding the shi: from infection barriers to the microbial city date: - - journal: nan doi: . /ips/olz sha: doc_id: cord_uid: lca xum how can a microbial approach to global health security protect life? contemporary infection control mechanisms set the human and the pathogenic microbe against each other, as the victim versus the menace. this biomedical polarization persistently runs through the contemporary dominant mode of thinking about public health and infectious disease governance. taking its cue from the currently accepted germ theory of disease, such mechanisms render a global city like hong kong not only pervasively “on alert” and under threat of unpredictable and pathogenic viruses and other microbes, it also gives rise to a hygiene and antimicrobial politics that is never entirely able to control pathogenic circulation. the article draws on recent advances in medical microbiology, which depart from germ theory, to invoke an ecological understanding of the human-microbe relation. here, while a small number of viruses are pathogenic, the majority are benign; some are even essential to human life. disease is not just the outcome of a pathogenic microbe infecting a human host but emerges from socioeconomic relations, which exacerbate human-animal-microbial interactions. in a final step, the article draws on daoist thought to reflect on the ways that such a microbial understanding translates into life and city dwelling. any visitor to hong kong will realize that disinfection is an urgent and pervasive imperative in contemporary everyday life in this global city. in late , hong kong was on the way to fashioning itself an antimicrobial global city. public signs on multiple surfaces including elevator buttons, escalator handrails, and floor mats duly inform the passer-by of hourly or daily sanitation. at various busy urban spaces, including mtr (metro) stations, walkways, libraries, and office and housing complex receptions, free hand sanitizer dispensers compel the passer-by to engage regularly in the act of public cleansing of the body. similarly, handbag-sized instant hand sanitizer bottles, readily available at every corner store or supermarket, with promises of killing " . percent of germs"; notices of hand-washing rituals; and the donning of masks by individual city dwellers, remind residents of the private acts of virus and bacteria control. all these practices of cleansing nourish an insidious sanitizing imperative in the defense against epidemic infections deeply enmeshed with the pulsating energies of an ambitious global city. it is the experience and fear of infection and death that accompanied the recent experience of the sars (severe acute respiratory syndrome) outbreak in , which precipitated this aggressive stance to potential contagions emerging in hong kong. li ( ) , a scholar of asian architecture, suggests that infection control in the form of public hygiene in contemporary postcolonial hong kong manifests itself in what he has termed "infection barriers." these antimicrobial-like-that is, antibiotic-and antiviral-like-physical and mental barriers aim to prevent the virus and other microbes from settling in the city. basing his interpretation on the traditional conception of the chinese city, "infection barriers" help him to analyze the historico-aesthetics of the city's contemporary urban defense against infectious diseases. li succinctly demonstrates how public hygiene is not only governed through overt public health programs but is affectively knit into both the fabric of the urban architecture and the tissue of the city population. infection barriers take the form of structures and widespread cleansing practices, which in li's eyes render hong kong a hospital disguised as a city. like other modern infection control mechanisms, the story of infection barriers in hong kong is one of setting the human and the virus against each other, as the victim versus the menace. this biomedical polarization, in which an external pathogen threatens the healthy human body, persistently runs through the contemporary dominant mode of thinking about public health and infectious disease governance (macphail (macphail , fishel ; white ; du plessis ) , which is rooted in the currently accepted germ theory of disease. it renders a city like hong kong pervasively "on alert"-albeit with chinese characteristics, as will be shown below. indeed, the polarization between the human body and the virus in global health constitutes "a world on alert" (weir and mykhalovskiy ; lee and mcinnes ) . "global public health vigilance," bolstered by an extensive transnational surveillance apparatus led by the world health organization (who), caters to a world under threat of unpredictable and pathogenic microorganisms and diseases. over the past two decades, a range of global health issues have reached the highest levels of political concern, prompting states and international organizations to respond to such threats in the language, and with the arsenal, of security (rushton and youde ) . worryingly, it has been suggested that these security practices render citizens as patients and states as megahospitals (elbe ) , as is also the argument in li's description of hong kong. in her excellent "pathography" of global public health's experience with the h n pandemic, macphail ( ) examines our collective fear of viruses by tracing the h n influenza virus through history and sites of public health activity, particularly in hong kong. the picture she paints is also of anxiety fueling an influenza pandemic narrative in which not only is the virus misunderstood but archaic truths of influenza research dominate (cf. webster ) and infection control stifles the development of necessary, novel ideas of infection control (schiffman ; lee ) . the fallacy of the influenza pandemic narrative lies in it largely misunderstanding the virus and bacteria and their relation to the human. recent advances in medical microbiology have found that the human-virus relationship is not one of opposition per se but of profound entanglement. one cannot be thought without the other, leading some to theorize the figure of homo microbis (helmreich ) . in this understanding, few microbes are pathogenic; most are benign, some even essential to human life. indeed, viruses have been and are a vital source of new genetic information, horizontal gene transfer, and genetic diversity in the evolution of life. zoonotic viruses' ability to continuously mutate as they go about infecting hosts and exchanging genetic information renders global health strategies largely obsolete. moreover, there is an increasing realization that antimicrobial interventions such as antivirals and antibiotics are accelerating antimicrobial resistance, making infection control strategies not just obsolete but also counterproductive. thus, a rethinking of the human-virus relationship in (urban) politics and security in hong kong and global health more generally is timely. the article begins by tracing the way the global city of hong kong has been constituted as an antimicrobial city since the sars outbreak in . the antimicrobial stance takes its cue from the scientifically accepted germ theory of disease. in a second step, the article explores the recent claims of medical microbiology, which profoundly depart from the germ theory to invoke an ecological or configurational understanding of the human-microbe relation. here, disease is not just the outcome of a pathogenic microbe infecting a human host but emerges from socioeconomic relations, which intensify human-animal-microbial interactions, thereby leading to pathogenesis-that is, the diseased state (lorimer ) . in a final step, the article draws on daoist thought and traditional chinese medicine to reflect on the ways that such an ecological understanding translates into life and city dwelling. sporadic outbreaks of h n in the live bird markets; the spectre of sars whenever someone with an acute, unexplained upper respiratory tract infection is hospitalized; the occasional case of japanese encephalitis; thick, humid air that feels pregnant with microbes; the soundless, nearly invisible mosquitos ubiquitous in the lush, dense patches of forest that cover the territory. contagions seem to originate both from within and from without. (macphail , ) in early , after having treated patients with atypical pneumonia in a guangzhou hospital, a medical professor arrived in hong kong from guangzhou carrying sars coronaviruses. the arrival of the coronaviruses led to the volatile outbreak of sars in hong kong. hitching a ride on the chinese professor, the pathogenic microbe family began infecting and reproducing among the large pool of hosts-that is, the hospital staff and medical students whom the chinese professor was visiting. during the professor's short stay at the metropole hotel in kowloon, before he himself fatally succumbed to sars, the viruses continued infecting seven other hotel guests, who traveled elsewhere in hong kong, singapore, vietnam, and canada. the viruses moved into the prince of wales hospital while journeying on a local hotel guest who was admitted in early march. there, they moved through the hospital, infecting over one hundred medical and nursing personnel. by early april, coronaviruses entered the housing estate "amoy gardens," where they infected and reproduced among the large pool of hosts living in and beyond this estate (lee ) . only a month later, coronavirus activities finally began to slow down and decrease-however, not before having also spread to a number of global cities including beijing, guangzhou, singapore, and hanoi in east asia as well as toronto. as hardy has aptly noted, "the history of the infectious diseases in modern times remains inextricably intertwined with the history of the cities that spawned them" (hardy , ; see also mcneill ) . this can be said too of hong kong. with the social and environmental conditions of a global city, the densely populated city is argued to have provided the necessary breeding and circulation ground for a fast-emerging disease such as sars to spread rapidly in the network of connecting global cities. cities afford microbes a large pool of closely connected human hosts by which a "sustainable chain of transmission" is ensured (harris ali and keil , ) . "the city is a playground for parasites," notes guardian writer kira cochrane and adds, quoting historian of science barnett (cochrane ), there are a lot more exciting human beings they can jump on to, . . . lots more opportunities for vectoring and transmission. it's all about movement. parasites love movement. so in that sense the city is an absolutely fantastic place for them. indeed, in hong kong, according to li shiqao, the sars outbreak brought into painful realization the problem with the city's characteristically chinese urban architecture of abundance or "maximum quantities," expressed through the functional building of ever-higher skyscrapers to house more and more people within ever smaller spaces (li , - ; also roloff ) . this specific urbanity of hong kong emerged with the unique political and economic circumstances that came with the arrival of large waves of mainland chinese refugees after the creation of the people's republic of china in . until the s, an estimated one million people were homeless in hong kong. before they were resettled in tiny spaces in public housing estates by the colonial authority, mainland chinese refugees lived in squalid squatter-settlements, which gave rise to the circulation of diseases and criminality (roloff , ) . throughout history, cities have responded in different ways to infectious diseases-from the traditional quarantine, to the development of urban hygiene infrastructure through sanitation and waste management systems (loos , - ; melosi ) , to the more recent establishment of public health systems. "the whole history of urban life," argues medical historian richard barnett, "is of living with parasites and trying to get rid of them" (as quoted in cochrane ) . indeed, in the modernization of cities in the late nineteenth century, gandy emphasized the way technopolitical discourses became entangled with advances in the medical sciences such as disease epidemiology to influence developments in civil engineering and planning, as well as public health (gandy , ) . writing about the inclusion of public hygiene in urban design and architecture, li shiqiao has spoken of "an architecture of bacteria and virus control" emerging in europe during this time (li , - ) . this found its expression especially in urban architectural designs of whiteness (which expresses the visual act of bleaching and antisepsis) and homogenous surfaces (which express the medical practice of disinfection) (li , - ) . thus, the concern for public hygiene and microbial control has shaped (particularly western) urban architecture since the turn of the twentieth century. chinese cities, on the other hand, first encountered the late nineteenth century european discourse of urban hygiene through "treaty-port cities" such as hong kong, shanghai, and tianjin, which were established to ensure the trading interests of western powers in china (rogaski , ) . cities like hong kong were to participate in late nineteenth century global trade, at a time when a bubonic plague was also spreading globally. hong kong's crowded architecture rendered it a gandy ( ) referred to this as the emergence of the "bacteriological city," to highlight the complex interactions between disease, water, and urban infrastructure. similar to concepts such as the "sanitary city" and the "hydraulic city" in analyzing the relationship between water and cities in the modernization of cities in late nineteenth century europe, gandy's "bacteriological city" nevertheless goes further in emphasizing the role of scientific advances such as disease epidemiology. according to li ( , ) , whiteness symbolizes "the visual act of bleaching, the physical and metaphorical removal of dirt as an antiseptic practice." it is reflective of ventilation and light in hospital design. "shine" is produced of homogenous surfaces that find their cue from the medical practice of disinfection. health strategies in china have traditionally focused on preserving the body. urban hygiene as a rationale was officially incorporated into the qing imperial administration in the early twentieth century and subsequently adopted by the communist government in . urban hygiene was linked to the nationalist project of the mao regime and launched in mass campaigns to eliminate disease and pest (li , ) . hong kong was created in the mid-nineteenth century as a result of the opium war between the british empire and the qing empire in china. having lost the war, the chinese emperor ceded hong kong in perpetuity to britain in . under british rule, the city was a free trade center with low taxation, a character it still holds today. its british heritage is an intensely neoliberal mentality reflected in a minimum government, few controls on imports and exports, and the lack of a military arm, which laid the ground for its eventual integration into the global economy and evolution into a global city. hygienically challenged city that was particularly vulnerable to infectious diseases, leading to urban hygiene becoming a fundamental feature in governing the colonial, and eventually postcolonial, city (li , - ) . historically, hong kong is considered a "naturally diseased space," where new influenzas emerge. with its "year-round humidity and swampy, tropical marshland," from the early times of british colonization hong kong was "seen as a reservoir-pit-of disease" (macphail , ) . a series of deadly outbreaks in the newly acquired colony led the british to set up hospitals and bring in western medical authorities to ensure there was little disruption to economic flow. the port of hong kong had become indispensable to the british economy and thus necessitated a strategic eye to controlling disease circulation (macphail , ) . in , hong kong experienced a plague outbreak which led to the establishment in of what would eventually become the bacteriological institute, its first modern microbiological research center (macphail , ) . while until the s hong kong's medical officials followed the widely accepted miasma theory in explaining infectious disease circulation, by the early nineteenth century, and with the establishment of the institute, the shift to germ theory in european medical circles had resolutely arrived in hong kong. using the new technology of the microscope, germ theory established that infectious diseases were not caused by atmosphericmiasma or "bad air" but by pathogenic microorganisms such as bacteria, protozoa, fungi, and viruses in the body. microbiologists proved that specific microbes, which spread from person to person, caused infectious diseases. germ theory radically changed the practice of medicine. it influenced how hospital space in hong kong and elsewhere had to be rethought toward including microbiological laboratories and isolation wards (sihn ). more importantly, as the accepted scientific theory of disease, which still underlies contemporary biomedicine, germ theory to this day influences and dominates modern sanitary practices and public health. the battle against sars, occurring only five years after hong kong's handover to china in , revealed considerable problems both with the sino-british political arrangement of "one country, two systems" and with the city's public health governance system. sars "can be understood epidemiologically as a virus that tested hong kong's healthcare system and governance to the maximum" (baehr , ) . while a number of stringent but important measures to control the spread of infections-including isolation and home confinement, regular health checks at the border, and public information sharing-were introduced during the outbreak, the hong kong government's response was widely considered to have been severely delayed and inadequate (ng , - ) . in fact, the change in political rule and the insufficient governmental response provoked a distinct cultural reaction to sars by the hong kong people who mistrusted mainland chinese and associated hong kong officials. culturally, baehr found the "mask culture," which arose during this time, a sign of an emerging social solidarity among hong kong people in which they paid tribute to a common good by meeting one's duty not to endanger the wider hong kong community. the plague, or any other pandemic in chinese culture, is traditionally seen as a sign of evil: it "summons up the possibility of a collective death: the extirpation of the social itself" (baehr , ) . mask-wearing thus "became the quickly improvised, if obligatory, social ritual: failing to don one was met with righteous indignation, a clear sign of ritual violation" (baehr , ) . in the immediate sars aftermath, partly to be seen to regain control of the battle against infectious diseases and partly to defend its beleaguered image as "asia's world city," the hong kong government aggressively promoted a new culture of urban hygiene (roloff , ) . building on the "positive hygiene spirit" and mask-culture during the sars outbreak, the city government began working to normalize a mentality of urban hygiene in the hong kong community. shortly after the sars outbreak, it established the governmental organization team clean. its role was to regain hong kong's status as a world-class city by instituting high hygiene standards throughout the city. former chief secretary for administration, donald tsang, declared on may , : there are problems emanating from personal hygienic habits, household hygiene unsatisfactory conditions and some environmental unhygienic problems relating to building maintenance and so on. . . . it is a monumental task but it is an important step that hong kong must go through if we aspire to be a city of the first rank and not only as a very successful international financial centre, but in fact a "clean room" in asia. (tsang ) the work of team clean began by identifying, defining, and clearing "hygiene blackspots" in nearly one hundred public housing estates. but the city's hygiene efforts extended not only to cleaning up buildings and surrounding infrastructure, it crucially involved changing the behavior of the people of hong kong: we believe that all efforts must begin with the self, extend to the family and the immediate neighbourhood, and then radiate throughout the entire community of hong kong before we can claim a place as a world-class city. (team clean report as quoated in roloff , ) by orchestrating mass campaigns of hygiene habits through posters, audio announcements, television broadcasts on public transportation, and the display of disinfection stations, public notices of disinfection routines, etc. and by incorporating regular and mandatory hand washing in schools, hong kong actively worked to induce an antimicrobial (sanitizing) imperative in the hong kong people. its stringent urban hygiene regime is creating hygienic world-class citizens who are to carry hong kong back into the top ranks of global cities (roloff , ) . in li's reading of the post-sars climate in hong kong, an architecture of bacteria and virus control was manifesting in distinctly chinese-style "infection barriers" in the city. historically, the chinese city is "conceived as a set of concentric corporeal defenses of the body, the family, the village, the work unit, and the state family" (li , ) . the preferred method of defense in traditional cities in china was walls. infection barriers in chinese cities like hong kong, li claims, take on some of the characteristics of the traditional walls in their concentric forms. unlike city walls or gated communities, however, infection barriers manifest according to the principles of antimicrobials. as such, in reproducing the chinese imperative of prudence in preserving the body, they defend the body by "fighting bacteria and viruses from within the tissues of architecture" (li , ) . in this way, the "monumental task" of transforming hong kong into an antimicrobial global city was underway. li concludes, "in hong kong, the hospital is poised to take over the entire city, spreading its standard practices of hand-washing, maskwearing, and temperature-taking" (li , - ) . building on germ theorywhich posits that pathogenic microorganisms such as bacteria, protozoa, fungi, and viruses residing in human bodies spread from person to person to cause infectious diseases-an extreme urban hygiene culture emerged in this global city to prevent germs from spreading. this is not only fueling and normalizing anxieties of infection and disease as i experienced when visiting hong kong in late , it may also not be achieving what it set out to do, namely, securing human life. considering recent advances in gene sequencing in microbiology, through which a "vast diversity of microbial life in, on and around the human body" (lorimer , ) has been identified as residing in complex relationality with one another, how befitting is it to fight infectious diseases by indiscriminately eliminating microbes through the use of antimicrobials and practicing urban hygiene as in the case of hong kong? what happens when the enemy is not the virus or other microbes but us (methot and alizon , ) ? like many others caught up in the emerging-disease narrative, which is based on the tenets of germ theory, the story of infection barriers is one of setting the human and the nonhuman virus against each other, as the victim versus the menace. viruses are commonly understood to be "'bad matter' to be prepared for, brought under control, and ultimately eradicated or rendered impotent" (white , - ) . unlike the germ theory of disease, which makes a specific microbe responsible for a specific disease (e.g., the coronavirus is responsible for sars), an ecological perspective holds that microbes are not essentially pathogenic (methot and alizon ) . rather, as hinchliffe et al. ( ) have argued, disease emerges from the complex entanglement between the immune system of a host and the microbial milieu in and outside of the host. various scholars have noted how, much like hong kong in the face of sars, global public health programs adopt an antimicrobial stance to the control and/or elimination of infectious diseases, however, which might prove to be counterproductive in securing human life (macphail ; methot and alizon ; fishel fishel , white ; hinchliffe et al. ; du plessis ; lorimer , ) . at the microbial level, ecological microbiologists understand most viruses and bacteria are not pathological; they are benign and even indispensable to human life. scientists are understanding better the causes of infectious diseases, but they also "increasingly hear about beneficial microbes and the consequences of their decline or absence" (lorimer , ) . causal links remain unclear and contested, however; as lorimer finds, there is "a widespread reappraisal underway in modern medicine of the salutary potential of the microbiome and the therapeutic use of microbes" (lorimer , ) . humans and microbes seem deeply and irrevocably entangled. this has led anthropologist stefan helmreich to consider the figure of homo microbis, made up of bacteria, viruses, fungi, and protozoa (helmreich (helmreich , . what are the implications of this understanding of the human body as mostly microbial to the way we fight infectious diseases in global cities and elsewhere? microbes are everywhere. apart from the ocean floors (helmreich ), soil, and deep forests, they inhabit nearly all of living matter, including mammals. humans are colonized by many viruses. this collection of viruses found in or on humans is known as the human virome, which is the viral component of the human microbiome-the assemblage of microorganisms including bacteria, fungi, protists, archaea, and viruses residing in/on the human body. only a minority of viruses infect human cells and can cause "acute, persistent, or latent infection"; some viruses are even "integrated into the human genome such as endogenous retroviruses" (wylie, weinstock, and storch ) , which are essential to human reproduction. "missing microbes" have arguably been linked to several metabolic, immunological, and mental health conditions, such as allergies, obesity, inflammatory bowel disease, and depression. see velasquez-manoff ; blaser ; and lorimer . endogenous retroviruses are fossil viruses which "began to be integrated into the human genome some - million years ago and now make up % of the genome" (tugnet et al. ) . they may be associated with autoimmune diseases such as rheumatoid arthritis, though evidence is still limited. yet, while many mammalian viruses, such as the endogenous retrovirus, picked up mammalian genes during their evolution by subverting these "to provide a selective advantage to the virus," an opposite story can be told too. an endogenous defective retrovirus "has been sequestered to serve an important function in the physiology of a mammalian host" by encoding a protein call syncytin. syncytin has been found to be vital in placenta production, a necessary prerequisite to human reproduction (mi et al. ; zimmer ). there is no scientific consensus on whether viruses are living matter. this is because viruses cannot live without a host cell: "they must invade and 'hijack' a cell's mechanism" so that they can produce the proteins needed for their own reproduction (macphail , ) . it is in this sense that van regenmortel and mahy ( ) have noted, viruses lead "a kind of borrowed life." their capacity to produce an effect-that is, their efficacy-, like other nonhuman matter, is "not only to impede or block the will and designs of humans but also to act as quasi agents or forces with trajectories, propensities, or tendencies of their own" (bennett , viii) . by not taking seriously their efficacy to alter the course of events, however, their animating role in evolution has until very recently been overlooked. viruses have been and are a vital source of new genetic information, horizontal gene transfer, and genetic diversity in the evolution of life, including increasing and decreasing immunity to certain viruses or bacteria. they have effected change on the direction of human evolution and were involved in the making of human history, most visibly in the form of plagues and diseases (mcneill ) . they are essential to sustaining the environment, including sea and freshwater regulation, as well as human reproduction; humans are deeply involved with viruses, in the positive and negative sense (fishel , ) . the vital role of viruses in human evolution necessitates an epistemological rethinking of evolution, as melissa a. white has noted, "from darwinian models of the 'survival of the fittest' to the phenomenon of emergent life" (white , - ) . viruses are able to evolve very quickly, reinventing themselves by mutation and adaptation, thereby "evading immune systems and other means of eradicating them" and "surviving under conditions that would cripple or kill other organisms" (macphail , ) . essentially, viruses are "packets of pure information" in that they are protein encasements of genetic material in the form of either dna or rna. rna viruses such as influenza a (responsible, for example, for avian flu in , the flu, and swine flu in ) evolve by engaging in "antigenetic drift" when mutating while replicating. zoonotic viruses that are able to jump species also evolve by engaging in "antigenetic shift" during which they exchange "entire genetic segments with other viruses inside a host" (macphail , ) . it is in this capacity that viruses ought to be recognized as "bioinformatic transport machines." indeed, white argues, "they ought to be considered active participants in creating the potentiality of new conditions of life through their capacity to assemble novel coalitions of genes" (white , ) . antigenetic shifts can change the surface proteins of the virus (the antigens), which are then no longer recognizable by the host's immune system, thus provoking a slower or no response to fend off the virus. virologists studying influenza a tend to focus on any incremental changes or dramatic shifts in genetic makeup to the viral antigens hemagglutinin (ha) and neuraminidase (na). it is after these specific antigens that influenza a viruses are named by their h and n numbers generally, scientists apply a list of a priori criteria to decide on life. following this, according to virologists van regenmortel and mahy ( ) , viruses today are considered somewhere in-between living and nonliving. similarly, theresa macphail ( ) argues, while viruses ought to be considered to have a "certain type of nontrivial agency," they are usually seen as "liminal objects" "with some of the properties of life, yet they cannot be considered fully 'alive' while outside of a permissive host." they are "organisms at the edge of life" (rybicki ) . in fact, historical viral traces in human dna were, until recently, controversially referred to as "junk dna." this noncoding dna makes up a greater portion of the human genome than "segments of dna that actively code for genes" (macphail ) . the human genome effectively consists of only two to three percent of coding dna, while the remaining ninety seven to ninety eight percent was thought to be just a "sea of genetic gibberish" with no biological function, hence "junk dna" (hall ) . this idea was debunked in by the encode group, which revealed that "junk dna" was in fact brimming with important genetic information. the encode group produced "a stunning inventory of previously hidden switches, signals and sign posts embedded like runes throughout the entire length of human dna." this essential noncoding dna, as macphail ( ) has noted, is evidence of past infections or "of a long-standing symbiotic partnership" with viruses. viral "junk" may even be responsible for creating new genes and for enabling the immune system to adapt to emerging infections (macphail ). (macphail , ). the pathogenicity of influenza a viruses is established both by their molecular makeup and their ability to cause serious illness in their host species, birds or other. a highly pathogenic virus causes severe or lethal illness in bird or other species populations. it is possible for a virus to "jump" from its host species into a human host, resulting in an usually severe and lethal infection. yet, viruses do not have "motives, or thoughts, or diabolical plans to wreak havoc to our cities"; "their function and purpose (if we can even say that they have one) is to replicate, to evolve, to survive" (macphail , ) . most viruses, however, infect microorganisms including bacteria in the human microbiome (edwards and rohwer ) . these prokaryotic viruses "affect human health by impacting bacterial community structure and function" (relman ; also wylie et al. ) . because viruses evolve very quickly, the human virome (and thus also the microbiome) is changing all the time. each human virome is different and unique as it evolves and is formed both by preexisting immunity and viral and human genetics as well as by human lifestyle, age, geographic location, and susceptibility to disease, all of which affect individual exposure to viruses (delwart ) . from this perspective, diseases are not the outcome of a virus or other microbe infecting a human, as germ theory holds, but emerge from the unique constellation of political and ecological relations that affect the biological interactions of the human, the animal, and the microbe and lead to the potential development of a diseased state-that is, pathogenesis. hinchliffe et al. usefully speak of disease as "multispecies conditions configured by specific socio-ecological 'situations'" (hinchliffe et al. ; lorimer , ) . some scientists already seek a shift toward this ecological or configurational thinking. the emerging diseases and global health security narrative runs on the notion that the bacteria or virus is the enemy against which the global surveillance / health security apparatus must operate (weir and mykhalovskiy ) . this narrative rests on the germ theory of disease currently dominating microbiology/bacteriology. in her pathography of the h n influenza pandemic in hong kong in , macphail finds that a few "heretic" microbiologists are challenging the dominant emerging infectious diseases narrative, calling for a new epistemology in which microbes are understood not as enemies but as coinhabitants of the world (macphail , ) . hong kong biologist frederick c. leung suggests that the problem with the alarmist influenza pandemic discourse lies partly in the way viral genetic data revealed through "signature sequences" has been interpreted by leading influenza scientists such as the virologist robert webster (webster ) . speaking against the central focus on the h and n proteins as the key to what makes an influenza virus deadly or not in the dominant influenza surveillance and research discourse, leung and others believe that "the public health orthodoxy has become too ready to see what it has already been prepared to look for and to fear" (macphail , ) . evolutionary biologist paul w. ewald suggests that although the h and n proteins are most visible to our immune system, it is not certain that they are the reason for a strain's pathogenicity or severity (macphail , ) . ewald believes that scientists tend to confuse "sources of variation-the mutation and recombination of genes-with the process of evolution by natural selection" (ewald , - ) . hong kong biologist frederick c. leung suggests that the problem with the alarmist influenza pandemic discourse lies partly in the way viral genetic data, revealed through "signature sequences," has been interpreted by leading influenza scientists such as the virologist robert webster ( ) . speaking against the central focus on the h and n proteins as the key to what makes an influenza virus deadly or not in the dominant influenza surveillance and research discourse, leung and others believe that "the public health orthodoxy has become too ready to see what it has already been prepared to look for and to fear" (macphail ) . evolutionary biologist paul w. ewald ( ) suggests that although the h and n proteins are most visible to our immune system, it is not certain that they are the reason for a strain's pathogenicity or severity. ewald believes that scientists tend to confuse "sources of variation-the mutation and recombination of genes-with the process of evolution by natural selection." to date, our understanding of the human virome, benign viruses, and the virushuman relation remains limited. yet, viruses may not simply be bits of "bad matter" that slow down, disassemble, and debilitate complex systems. rather, viruses might well be approached from another vantage point altogether, as vitalizing forces in complex ecological systems in which humans are not the center. (white , ) the relation between the human and microbial communities is not antagonistic but symbiotic. while the rapid emergence of infectious diseases is creating a "world on alert," as weir and mykhalovskiy ( ) have observed, it demonstrates the frail character of the ecological balance of this vital symbiosis between humanity and their vital environment (methot and alizon , ) . the study of the biology and ecology of viruses forces us to appreciate our mostly symbiotic relationship with viruses and other microbes. it compels us to rethink how (human) life has come to be. it is not the darwinian paradigm of "the survival of the fittest" but rather an emerging paradigm revolving around a microbiological understanding of "emergent life" that explains our evolution. it also necessitates that we understand and respond to disease not as the invasion of enemy microbes but as the pathogenesis, that biological mechanism, of a unique constellation of politico-ecological relations and human-animal-microbial interactions, which gives rise to a malady. how can this emerging ontological and epistemological understanding of human life inform the governance of disease? the best defence we have against microbes is our brains, which can surely work out how to live in harmony with the microbes we know, and find non-disruptive ways of combating those that emerge in the future. (crawford , ) how do we live in harmony with the microbial world but still prevent infectious diseases from developing? how do we move from a potentially destructive antimicrobial perspective such as is embodied in hong kong to a microbial perspective in which we take responsibility for our vital relation with the microbial world? new materialist thinking (cf. hinchliffe ; coole and frost ; dolphijn and tuin ), which takes seriously the efficacy and ecology of human bodies and nonhuman bodies such as the virus and other microbes, invites us to examine how the human-microbe relationship can be rethought in politics. while a number of theorists have begun to conceptualize a new materialist politics and ethics within modern political theory (bennett ; connolly ; mitchell ) , others have looked to indigenous cosmologies, which take into account the world we share with other kinds of beings, to formulate a postanthropocentric politics (kohn ; tsing ; du plessis ) . the daoist cosmology underlying chinese medicine and chinese strategic thought and practices provides a first step to think in distinctly chinese ethical terms about how public health strategies in hong kong and beyond can begin to direct a human-microbial ecology to the advantage of protecting all life. daoist thought takes reality as dynamic, and the regulation of this changing reality is immanent to the interaction of the heterogeneous factors involved, thus emerging spontaneously (jullien ). sunzi's philosophy strategizes how best to direct a heterogeneous ensemble of human and nonhuman (virus, bacteria, and other nonhuman) bodies, by shifting the inherent potential, the shi, of this ecology to our advantage. in the art of war ( - bce), success in war was achieved not through the courage, activity, and talent of any individual fighter but through careful planning instead of actual combat. in fact, combat in chinese thought is not violence; violence is to be avoided. in medicine too, defending the body from danger demanded care for the body manifested in preservation regimes instead of reactive "western drug-and surgery-based medical practice" (li , ) . chinese medicine is about preserving rather than curing. this can be seen in its guise as a conception of food: it demands specific diet regimes developed from "observations of the characteristics of the vegetation and animals in the season." over time, it came to incorporate a puzzling spectrum of diet-based caring regimes that are still widely practiced today (li , ) . reflecting on this, medical anthropologist judith farquhar has noted of chinese medicine that it "heals in a world of unceasing transformation." this a priori dynamism in chinese medicine contrasts sharply with the modern western "world of discrete entities characterized by fixed essences, which seem to be exhaustively describable in structural terms." since motion and change are a given, they rarely require explanation with reference to their causes. according to farquhar, "one consequence of this dynamic bias in chinese medicine is that the body and its organs (i.e., anatomical structure) appear as merely contingent effects or by-products of physiological processes" (farquhar as quoted in needham ) . in a comparable vein, methot and alizon ( ) and others (hinchliffe and bingham ; lorimer ) have argued that pathogenesis results not from any single pathogenic microbe but from the configuration of socio-ecological relations and human-animal-microbe interactions. chinese thought, francois jullien explains, takes reality as an immanently "regulated and continuous process that stems purely from the interaction of the factors in play (which are at once opposed and complementary: the yin and yang)" (jullien , ) . reality is dynamic, and the regulation of this transformative reality-that is, the order of reality-emerges spontaneously. it is not achieved through external intervention but is "entirely contained within the course of reality, which it directs in an (inherent) fashion, ensuring its viability" (jullien , ) . two notions are central to this ancient chinese strategy: (a) the notion of a situation or configuration (xing)-that is, as a relation of forces such as are immanent to an ecology-and (b) the notion of the potential (shi) of a situation/configuration. this is commonly illustrated by "a mountain stream that, as it rushes along, is strong enough to carry boulders with it" (jullien , ) . the configuration (xing) of the mountain consists of a downward-sloping course and narrow channel, while this configuration itself gives rise to the potential (shi) for the rushing stream to carry boulders with it. thus, it is not "what we ourselves personally invest in the situation" that counts so much but rather "the objective conditioning that results from the situation" (jullien , ) . jullien has argued that shi helps to "illuminate something that is usually difficult to capture in discourse: namely, the kind of potential that originates not in human initiative but instead results from the very disposition of things" (jullien , ) . bennett ( , ) usefully elaborates on this by explaining that "shi is the style, energy, propensity, trajectory, or élan inherent to a specific arrangement of things." for bennett, "shi names the dynamic force emanating from a spatiotemporal configuration rather than from any particular element within it." as "both the membership (of a configuration or assemblage) changes over time and the members themselves undergo internal alteration," as bennett points out, the shi or mood of a configuration also changes (bennett , ) . in margaret archer's words, everyone in the configuration "possesses autonomous emergent properties which are thus capable of independent variation and therefore of being out of phase with one another in time" (archer , ) . it is possible that an individual element such biophilosophers deleuze and guattari ( ) describe something comparable when they discuss the milieu as a force field composed of nonhuman and human things (xing). not only do these heterogeneous elements constituting a milieu each entail some form of efficacy, but the milieu as a whole gives rise to a potential to effect (shi). jane bennett ( ) likewise argues that there is an agency that attaches to assemblages of human and nonhuman entities. she contends that this agency of an assemblage is comparable to the chinese strategic notion, shi. as a virus, in an antigenic shift, "becomes out of sync with its (previous) self" and forms new relations within an assemblage, "leaning towards a different set of allies" (bennett , ) . as such, the members of an assemblage "maintain an energy potentially at odds with the shi" (bennett , ) . it is for this vibrancy, according to bennett, that the agency of assemblages cannot be understood in terms of passive social structures. crucially, in chinese strategic thought, it is the shi that "can be made to play in one's favour" (jullien , ) . it is because of their variability that circumstances or ecologies can little by little be turned advantageously by the propensity or efficacy immanent to a situation. a chinese sage, according to jullien, "is inclined to concentrate his attention on the course of things in which he finds himself involved in order to deter their coherence and profit from the way that they evolve" (jullien , ) . a good general, in turn, "must be able to read and then ride the shi of a configuration of moods, winds, historical trends, and armaments" (bennett , ) . this "logic of regulated evolution" allows the potential of a situation "to develop of its own accord and to 'carry' us with it" (jullien , ) . jullien illustrates this by drawing on an old chinese proverb that captures the core idea of this thinking (mencius as quoted in jullien , ) : "even with a mattock and a hoe to hand, it is better to wait for the moment of ripening." unlike the western tradition of establishing a model that is projected onto a variable reality, according to jullien, chinese thought will concentrate on understanding how things unfold so as to discover their configuration (relationality) in order to come up with alternative ways to effect a more advantageous outcome. thus, instead of constructing an ideal form that we then project on to things, we could try to detect the factors whose configuration is favourable to the task at hand; instead of setting up a goal, we could allow ourselves to be carried by the propensity of things. (jullien , ) to ride the shi-in other words, to live harmoniously alongside and with the microbial word-we need to identity those factors whose configuration is favorable to human life. daoist ethics and chinese strategic thought lead us to embed homo microbis in an environment that is favorable to all life. as hong kong biologist frederik leung points out, the problem not only lies in the prevailing dominance of germ theory in science, it also lies in the way we relate to the animal and nonhuman world at large with which humans are so deeply entangled. he speaks against the culling of birds and animals as a response to an emerging influenza pandemic (macphail , ) . in fact, the flu is argued to be unpredictable only because influenza experts "don't understand the basic science" (leung, as quoted in macphail , ) . viruses naturally undergo constant mutation. in the case of cross-species transmission, such as the sars coronavirus which crossed over from civet cats to humans in , it became clear that "highly pathogenic influenza viruses naturally burn themselves out, . . . they pose no greater risk to humanity than 'normal' influenza viruses" (macphail , ) . in fact, "the more virulent the virus, the faster the virus dies out. by evolutionary principle" (leung, as quoted in macphail , ) . leung laments the current focus on the development of influenza vaccines, since intervention through the vaccine encourages further mutation, whereas allowing the virus to take its natural course leads to its natural burn out (macphail , ) . leung's call for rethinking how we relate to the animal world echoes the recent effort to do just that in the one world one health initiative of scientists, physicians, and veterinarians worldwide to collaborate across disciplines in addressing emerging diseases. in part, this effort came about due to concerns for shared risks across human, animal, and environmental health. the focus, however, has tended to lie on the contamination and transmission of pathogens rather than on the socioeconomic relations underlying disease and health. it has been criticized for reducing diversity and for underappreciating the local, contingent, and practical engagements that first make health possible (hinchliffe ) . yet, it is not just how we relate to the animal world that matters. it is also about how we think about life in cities, especially as sars in hong kong in revealed, a set of absent actors-animals, microbes, airplanes, sewage systems, respiratorsthat had been banished to the margins of our conceptions of urban life, even as they actively contributed to how urban lives were composed and lived. (braun , ) the sars encounter and the post-sars politics force us to think about the microbes, animals, and many other organisms living amongst us and influencing the "social" collectives of humans. that social collective, the city, needs to be rethought on microbial terms. at the turn of the twentieth century, cities thrived on "bacteriological" (gandy ) and "epidemiological" conceptions of urban spaces in europe and north america. they aimed to transform urban spaces and the behavior of city people accordingly (braun , ) . in his exploration of the chinese city, li shiqiao highlights the key imperative of prudence, understood in terms of "the principle of endurance and an unknown future reward," which firmly runs through chinese conceptual thought (li , ) . he interpreted this in the post-sars situation of hong kong to be the donning of masks and ultimately striving to become hygienic subjects. yet, it seems prudent to build a microbial instead of an antimicrobial city, to rethink space and the behavior of the city people in hong kong and other (global) cities in ecological and sustainable terms, and to take into account the social-economic relations that intensify human-animal-microbial interactions. this article set out to show how a better understanding of the microbe and its deeply entangled existence with humans is crucial to conceptualizing a better approach to health and life. specifically, it argued for an inclusive approach to the virus and other microbes with which we share the world we live in over an exclusively oppositional approach to eradicating pathogenic circulation, which also eliminates or mutates benign viruses essential to human life. the article began by looking at the antimicrobial politics in chinese postcolonial hong kong since the turn of the century. it particularly focused on the notion of "infection barriers" advanced by li ( ) . li bases his analysis on the traditional conception of the chinese city and the practice of defense in walling the city off against danger. by arguing that, in the struggle against infectious diseases, contemporary practices of urban defense have taken on another guise, namely infection barriers, li is able to demonstrate how the politics of public hygiene operates not only through overt public programs but through infection barriers that are affectively knit into the fabric of the urban architecture and tissue of city dwellers. although his lens on chinese urban defenses takes seriously ancient chinese thought in the making of urban spaces, nonetheless, the politics of infectious disease remains caught up in the prevalent and dominant oppositional narrative of the human against the microbe. infection barriers set up the human and the nonhuman virus against each other, as the victim versus the menace. like antivirals and antibiotics, urban hygiene practices are never entirely able to control pathogenic circulation. this is because urban hygiene proceeds on the basis of a very narrow conception of disease, namely the widely accepted germ theory of disease. by studying the biology of microbes, it becomes possible to grasp more what the virus and other microbes are and do but particularly how they relate to the human. first, the activities of the virus escape the political designs, regimes, and practices because the virus and other microbes are forever in transformation. how then can human efforts be conceived to control pathogenic, while fostering benign, viral circulation? second, viruses play a large and essential part in making up the human. while a small number of viruses are pathogenic, the majority are benign, and some are even essential to human life. strategies to eliminate them may kill pathogenic viruses but essential viruses might also be killed off in the process. as the human cannot be thought without the virus, and attempts to alter or eliminate it (in)directly also affect the human, how might we think differently about urban spaces and public health if we consider the human and the virus not as opposed but as fundamentally interrelated? finally, the article considered daoist thought, to begin to reflect on the governance of microbes, which takes seriously their efficacy, dynamism, and deeply historical relationality with humans. from the biological vantage point of ecologies in which the virus, the human, and many other organisms are fundamentally interconnected forms that vitally depend on, but can also harm, each other, all interventions to control viruses will affect all involved, including the virus as well as the human. thus, it is in the interest of human beings to proceed with interventions to control viruses that cause the least direct or indirect harm to humans. daoist thought offers some ideas for how to strategize public health schemes, which take due consideration of this deep involvement of viruses and humans. public health schemes that develop defenses against pathogenic viral circulations, especially in a densely populated global city such as hong kong, remain important. however, there is also a need to consider and adapt the human practices that both create(d) the easy passages for viral circulation as well as forced viral mutations through the overuse of antiviral (and antibiotic) agents or vaccine development which is thought to have led to antiviral resistance. most of all, rather than fostering an oppositional relation between the human and the virus, there is a need for an appreciation of the vital role of the virus in human lives as well as of how deeply we are entangled with the virus. instead of only arming against pathogenic viral circulation by sanitizing both the urban environment and the minds of city dwellers, as in the case of hong kong, such circulation might be more usefully countered by championing an approach that proceeds on the understanding that the human irrevocably inhabits an ecosystem in which the multiplicity of life forms are deeply interrelated and dependent on each other. much like the chinese general evaluating the course of things immanent to a situation, since humans thrive on a range of other beings doing well, "an interest in human security becomes an interest in biodiversity: thriving is not a zero-sum game between different species, in fact, quite the opposite" (du plessis , ). global health projects ignore this and are struggling to deliver what they aim to do. modernity at large: cultural dimensions in globalization. public worlds realist social theory: the morphogenetic approach city under siege: authoritarian toleration, mask culture, and the sars crisis in hong kong the agency of assemblage and the north american blackout vibrant matter: a political ecology of things missing microbes: how killing bacteria creates modern plagues thinking the city through sars: bodies, topologies, politics the rise of the network society sick cities: why urban life is breeding new illness fears the fragility of things: self-organizing processes, neoliberal fantasies, and democratic activism new materialisms: ontology, agency, and politics deadly companions: how microbes shaped our history a thousand plateaus: capitalism and schizophrenia a roadmap to the human virome new materialisms: interviews and cartographies when pathogens determine the territory: toward a concept of non-human borders viral metagenomics security and global health: towards the medicalization of security plague time: how stealth infections cause cancers, heart disease, and other deadly ailments microbes the bacteriological city and its discontents journey to the genetic interior the epidemic streets: infectious diseases and the rise of preventive medicine - networked disease: emerging infections in the global city homo microbis: the human microbiome, figural, literal, political more than one world, more than one health: re-configuring interspecies health mapping the multiplicities of biosecurity pathological lives: disease, space and biopolitics the propensity of things: towards a history of efficacy in china how forests think: toward an anthropology beyond the human revealing power in truth global health and international relations. cambridge: polity. lee, shi hung understanding the chinese city. theory, culture and society. london: sage. loos, adolf. . "plumbers parasites, ghosts and mutualists: a relational geography of microbes for global health the viral gene: an undead metaphor recoding life the viral network: a pathography of the h n influenza pandemic. expertise: cultures and technologies of knowledge plagues and people the sanitary city: urban infrastructure in america from colonial times to the present. creating the north american landscape what is a pathogen? toward a process view of host-parasite interactions syncytin is a captive retroviral envelope protein involved in human placental morphogenesis only human? a worldly approach to security part vi: medicine. science and civilisation in china: biology and biological technology globalization of sars and health governance in hong kong under "one country, two systems are viruses alive? the human microbiome and the future practice of medicine hygienic modernity: meanings of health and disease in treaty-port china die sars-krise in hong kong: zur regierung von sicherheit in der global city routledge handbook of global health security the classification of organisms at the edge of life, or problems with virus systematics the global city reorganizing hospital space: the plague epidemic in hong kong and the germ theory transcript of the press conference with the chief secretary for administration in the conference hall of the central government offices new annexe on may the mushroom at the end of the world: on the possibility of life in capitalist ruins human endogenous retroviruses (hervs) and autoimmune rheumatic disease: is there a link? an epidemic of absence: a new way of understanding allergies and autoimmune diseases influenza global public health vigilance: creating a world on alert. routledge studies in science virus emerging view of the human virome mammals made by viruses i thank the anonymous reviewers and the editors of ips for their generous comments. i am also grateful for insightful comments on earlier versions of the article presented at the eisa convention , ewis , and before the irss research group, university of groningen. i am especially thankful to gitte du plessis, luis lobo-guerrero, and christopher long for thought-provoking nudges. this paper was produced under the aegis of the groningen centre for health and humanities and the aletta jacobs school of public health, university of groningen. key: cord- -afxh rks authors: yip, paul; chan, milton; so, b. k.; wat, k. p.; lam, kwok fai title: a decomposition analysis to examine the change in the number of recipients in the comprehensive social security assistance (cssa) system date: - - journal: china popul dev stud doi: . /s - - -z sha: doc_id: cord_uid: afxh rks social security is an important social and public policy measure to help address poverty in any contemporary society. the comprehensive social security assistance (cssa) system in hong kong provides a safety net for those aged children and adults below years old who cannot support themselves financially. it is designed to bring their income up to a prescribed level to meet their basic needs. the rapid increase in social welfare expenditure in the last decade has become a concern to the hong kong sar government. the overall social welfare expenditure has accounted for nearly . % of government expenditure in , with the total amount increasing from $ billion to $ billion (an increase of . %) for the period - . however, the amount spent on cssa only increased from $ . billion to $ . billion with an increase of . % only for the same period. the much slower magnitude of increase is related to the reduction in the number of cssa recipients, which decreased from , to , over the period. a decomposition method was used to assess the changes in the number of people in the cssa system. it showed that the rate of arriving into the system has been decreasing due to a robust economy with a very low unemployment rate; whereas moving out of the system has also been decreasing in the past years. this phenomenon can be partly attributed to the widening of the income gap in the community in the period. despite the increase in population size, as long as employment conditions remain strong and the momentum of leaving the system can be maintained, the number of cssa recipients will continue to decrease. however, the results also suggested that a certain proportion of cssa recipients will not be able to move out of the system and have been trapped. some innovative methods to help them out of cssa are discussed. in view of the poor economic outlook arising from the covid- pandemic, it is important for the government to have effective measures to keep people in their jobs. if the unemployment rate will does not substantially increase and then increase of in cssa recipients can be contained. social security is an important social and public policy measure in any contemporary society. it is designed to bring low-income groups up to a prescribed level to meet their basic needs such that affected individuals and households can have some relief and reposition themselves for the next stages of life. it is particularly relevant to the key global concern of helping those who are unable to support themselves. "leave no one behind" is the slogan adopted by the united nations' sustainable development goals (united nations ), and ending poverty, everywhere, in all its forms, is the first of the sustainable development goals (sdg). there were . million people living below the poverty line in hong kong in , accounting for . % of the total population of . million, (poverty report ) . researchers have argued that poverty can be alleviated by social security through redistributing resources towards the poor (jones ; midgley ) , and local statistics prove that social security can make a significant difference to hong kong's poverty situation (poverty report ). for hong kong, after accounting for government recurrent cash benefits (including various kinds of social security schemes including cssa), the size of the poor population was reduced from . million to just over million ( . % of the population)-a % reduction in the size of the poverty population. hong kong's social service expenditure accounted for more than . % of hong kong government expenditure, equal to about $ billion, and it increased by . % for the period - whereas the expenditure on cssa only increased by . % from $ . billion to $ . billion for the same period. on the other hand, the non-means tested social security allowance (ssa) scheme for older adults aged or over increased by . % from $ . billion to $ . billion, which is a worrying economic sign for a rapidly ageing society. reducing the number of dependents in the social security system and maintaining a dynamic and vibrant economically active population is a high priority concern for policy makers of any government. a good understanding of the movement in and out of the social security system will be helpful in formulating effective interventions to reduce the number of social security recipients and to ensure financial sustainability of the system. yip et al. ( ) proposed a stochastic model to examine the in-and out-movement in the cssa scheme and identified that the group aged - with children had the largest impact on the number in the system. the results suggested that preventing this group from entering the cssa system would be more effective in reducing the number of cssa recipients than policies that aim to help them exit. it is a good illustration of the rose theorem, which asserts that the impact of "reducing a small risk in a large population" is more effective than "reducing a high risk in a small population" (rose ; yip et al. ). on the other hand, intergenerational poverty is of particular concern to policy makers (peng et al. ) . it is of great concern for helping those people who are trapped in poverty. upward mobility seems to be stagnant and poverty has become a structural problem in the community, especially among ethnic minorities (poverty report ). in this study, we adopt a decomposition analysis to assess the impact of population growth and age structure on the numbers of people moving in and out of the cssa scheme for the period - . it is an improvement on earlier work that did not take into account the moving in and out mechanisms (yip et al. ) . here, the proposed method disentangles the overall effect of the changes in number of people in the cssa scheme at two different time points from the effect of demographic transition size and age structure. hong kong has a minimalist social welfare support system as compared to other western countries. the government promotes self-reliance, and the hong kong people are also not used to relying on handouts by the government. the amount of assistance under the cssa scheme is determined by the monthly income and recognised needs of a household. the difference between the total assessable monthly income of a household and its total monthly needs as recognised under the cssa scheme in terms of various types of payment will be the amount of assistance payable. when assessing a household's monthly income, earnings from employment and training/retraining allowance can be disregarded up to a prescribed level so as to provide an incentive to work and to recognise the additional expenditure incurred in attending training/retraining courses. the applicant must fulfil the residence requirement and pass both the income and asset tests. persons aged - in normal health should actively seek full-time jobs and participate in the support for selfreliance scheme (sfs) of the social welfare department (swd) if they are unemployed or working part-time or earning less than a reasonable wage as defined by swd. the cssa payments can be broadly classified into three types, namely, (a) standard rates; (b) supplements; and (c) special grants. under the cssa scheme, different standard rates are applicable to different categories of recipients. in addition, the cssa scheme provides various supplements to specified recipients, such as elderly persons, persons with disabilities or in ill-health, single parents and ablebodied adult recipients aged to . a wide range of non-standard payments in the form of special grants are also payable to meet expenses such as rent, school fees and other educational expenses, and medically recommended diets/rehabilitation/ hygienic items. details can be seen at https ://www.swd.gov.hk/en/index /site_pubsv c/page_socse cu/sub_compr ehens /. the social welfare department has provided the number of cssa recipients by age group as of the end of and , and the number of cssa recipients with duration on cssa of less than year by age group. these allow us to estimate the number of arrivals to and removals from the cssa system (see table ). the data excluded the , foreign domestic helpers who are not entitled to receive cssa. the dataset was categorized into cssa-arrival and cssa-removal, and by age group. in this study, we used age group categories ( - , - , - , - , - , - , - , - , - , - , - , - , - ) . for those who aged over , a different scheme named social security allowance (ssa) is available. the objective of the ssa scheme is to provide a monthly allowance to hong kong residents who are severely disabled or who are years old or above to meet special needs arising from disability or old age. the ssa scheme participants are not required to go through a means test. hence, the mobility out of the ssa scheme is non-existent as it is really a welfare payment for older adults depending on their needs and it is also non-contributory. hence, in this paper we only examine the movement of the cssa recipients of the group of aged - only. stratified data for the two time points and were then used to conduct the decomposition analysis. the cssa scheme in hong kong provides a safety net for those who cannot support themselves financially. it is designed to bring their income up to a prescribed level to meet their basic needs. the applicant must pass both the income and asset tests. the cssa cases of young people aged or below is usually based on their parents/guardians. not all household members are eligible as each member needs to satisfy the criteria on income level and residence right. k age group; t year: equals for and for ; � p kt arrival rate of non-cssa population within group k in year t q kt removal rate of cssa population within group k in year t n kt net change in number of cssa population within group k in year t a kt − r kt the number of new arrivals and removals in year t can be expressed as the product of three components summing across age-size groups as in ( ) and ( ) respectively: ( ) in eq. ( ), the first component ( p kt ) refers to the age-specific arrival rate effect ( r ), which measures the arrival rate within age group k . the overall arrival rate is the sum of the specific arrival rates in the year. the second component ( x kt x .t ) refers to the agespecific effect ( q ), which measures the ratio of the kth age group with respect to the non-cssa population size. the third component ( x .t ) refers to the non-cssa population size effect ( p ). similarly, eq. ( ) specifies the age-specific removal rate ( q kt ) effect ( r ), age-specific ( equations ( ) and ( ) are the product of the three components. the kitagawa's decomposition (kitagawa ) was used to differentiate the relative contributions of r and q and p , r and q and p effects from the change in overall newly arrival and removal population for the two time periods, respectively. with reference to eqs. ( ) and ( ), they are the product of two components. the decomposition can be simplified as below: the r , q and p effects sum up to give the change in the arrival number and removal number, thus giving the rate of change of cssa population size. the age composition effect non -cssa: the age composition effect cssa: the non -cssa population size effect ∶ p effect = ∑ k p k + p k the cssa population size effect: the arrival rate to cssa effect: the removal rate from cssa effect: we take the arrival size as the sign of the net change, i.e. net arrival. as removal size effect contributes a negative impact on arrival size effect, we can calculate the net change (arrival) size at time t from we can further calculate the difference between two different time points, i.e. change of net arrival size, from table gives the changes in arrival and removal sizes, total cssa and non-cssa sizes, arrival and removal rates, and the decomposition of the changes ( minus ) into age ( q , q ), size ( p , p ) and rate ( r , r ) effects over the period - by -year age group. it showed a healthy sign that the number of people remaining in cssa has been continuously decreasing monotonically from , in to , in , with , having left the cssa scheme for the whole period. the changes in the number of arrivals and removals in - were and , respectively. both the arrival and removal rates have been decreasing, with the arrival rate reducing from . to . %, and the rate of leaving reducing from . to . %. thus, while fewer are entering the cssa system, there has also been a reduction.in the number of removals from cssa. table suggests that increases in the population size for the period - resulted in an increase of people into the cssa scheme. while the age effect also contributed people to cssa as older people had a higher rate in joining the scheme. on the other hand, the improvement in the arrival rate contributed to a reduction of the number of cssa recipients (− ). the positive effect in containing the growth in cssa recipients is offset by the increase from the population growth (+ ) and ageing of the non-cssa population (+ ), with a net reduction − for the period - . for the removal, decreases in the size of the cssa population accounted for the majority of the reduction of the number of removals, with a difference of − between and , and the effect of ageing also slowing down the number of removals by − . more importantly, the reduction of removal rate between and contributed negatively to the number of removals (− ). the age group of - had the highest reduction of removal from the cssa, which might relate to the recent increase in youth unemployment (especially those who are not in school and unskilled) in hong kong. the negative sign suggest a stagnation of the cssa recipients in the system. however, there was a notable positive contribution made by improvements in employment among older adults aged - leaving the cssa system (+ ). figure depicts the size of age specific movement of cssa recipients in and out of the system for the period - , with the size determined by the rate and associated population size. for the arrivals, there has been a consistent improvement in the reduction of cssa recipients for all age groups except for a slight increase among older adults (+ ). however, as the ageing effect has become more significant than before, the size of the arrival for the age group - is still positive compared to , as the improvement in its rate has completely been offset by the ageing effect despite improvements in preventing older adults from entering into the cssa system. for the removal, all of the age groups have experienced a reduction of removal rate of leaving the cssa system except for the age group - . the reduction of the removal rate is worrying, as it indicates that nearly all of the cssa population found it harder to remove themselves from being a cssa recipient in compared to . the increase in the number of removals in the - age group is noteworthy. this can be attributed to significant improvements in rehiring older adults into the workforce. the working participating rate among older adults in the period has improved due to incentivization and increases in job opportunities for the older population (table ). the decomposition analysis allows us to examine the impact on the number of cssa recipients of changes in arrival and removal, population size and age distribution. it showed that the number of hong kong's cssa recipients has been decreasing for the period - , mainly due to changes in the number of removals ( %) and arrivals (− %). the robust economy with a very low unemployment rate ( . %) in hong kong helped to reduce the chance of becoming a cssa recipient from . to . % during - . on the other hand, the rate of removals decreased from . to . %, indicating that it is more difficult than before to leave the cssa system. it has been shown that having a job is the most effective way to stay out of the cssa system (poverty report ). the government has tried to improve the incentive for low-skilled workers to join the work force by introducing the transport subsidy scheme in , covering % of fares beyond hk$ per month. with a threshold of hk$ income per month, within which applicants must fall, the scheme has excluded a large percentage of low-income workers with earnings just above the threshold that are struggling to have a reasonable quality of life. (sha et al. improving employment opportunities for older adults (aged - ) is important in keeping them out of cssa, therefore it is encouraging to see (as shown in table ) that more people in this age group are keeping their work and/or getting a job such that they do not have to rely on the cssa system. some members wish to work and have the ability to work beyond their retirement age. the usual retirement fig. changes in the number of arrivals and removals between and by five-year age group age in hong kong workforce is years whereas the hong kong life expectancy has increased to years old (c&sd ). removing barriers to working at older age would be a win-win scenario, especially in view of the shortage of workers due to hong kong's ageing society. some of the major barriers to retaining older adults in the workforce are the complicated procedures and expensive medical insurance, which is a major concern of many companies employing older adults (encouraging young-olds employment ). some infrastructure support and more flexible arrangements in the working environment would be conducive to increasing the working participation rate among older adults. for the removal rate, the propensity of leaving continues to decrease, reducing the number of removals and the number of cssa recipients remains high. apparently, inertia has been building in our system such that some people cannot move out from cssa. they are trapped in the system, or they have become the structural poor. for example, in view of the rising divorce rate in hong kong, single parents with young children that are lacking support from their families are particularly affected. without sufficient childcare service, the women would have more difficulty to participate in the workforce. furthermore, children from cssa families have been shown to have lower self-esteem (yip ) . to avoid issues of structural and stubborn poverty, we need to provide training and retraining programs for those who still have the ability to re-join the workforce. more family friendly working environments would be helpful to increase female labour participation to break down intergenerational poverty. another vulnerable group, the migrants daily from mainland china might have an impact on the increase in the number of cssa recipients. however, in reality most of them do not resort to seeking support from the cssa (lee and chou ) . nevertheless, more effort should be made to engage mainland migrants successfully to remove barriers to their workforce participation. also, these migrants are mainly the spouses and children of hong kong residents, with socioeconomic profiles generally inferior to local residents. they often experience problems in finding jobs due to lack of skills, qualifications and the language barrier (government of hong kong special administrative region ). the new female migrants also have to look after young children. the insufficient child care support has made it difficult for the female migrants to participate in the work force which can create sort of structural financial dependence (yip ) . some poverty among new migrants also relates to the lack of recognition in hong kong of qualifications earned in mainland china, and this may constitute a waste of human capital (chou et al. ). the specific poverty rates in the groups of old age and large households are higher than the population average (lee and chou ) . also, it is a good time to re-examine the wage especially for the low skilled workers and outsourcing arrangement of the government services. sometimes, the working wage is so low that it discourages people looking for work. the low wage is indeed a complicated issue which depends on the supply and demand of the workforce. nevertheless, coupled with low wages, unfair treatment by some employers, limited amount of protection of the labour law, and extreme profit-seeking behaviour by outsourcing companies, these workers can find themselves unable to improve their quality of living through regular employment, and have to work overtime in order to satisfy their basic needs, at the expense of their own and family well-being and society's welfare. sometimes, they don't have a choice but by becoming a cssa recipient. the paper has examined the impact of the demographic transition on the number of cssa recipients. indeed, the cssa recipients also depends on the household structure and changes for the period - . unfortunately, the cssa household data is not available for analysis. nevertheless, individuals under would not be eligible to apply for cssa. hence, all the cssa recipients under years old should be dependent of the adults recipients. changes in the age group - would be closely related to the number of recipients of aged - . access to social security is a lifeline for the vulnerable groups in the community, and forms the major expenditure component of social welfare spending in hong kong. being employed is the most effective way to stay out of the cssa (poverty report ). the economy has been strong despite the relatively low working wage. the majority of recipients would not apply for the cssa if there is other alternatives. nevertheless, our economy remains outward-oriented and more than % (poverty report ) of our workforce ( . million out of . million) is employed in service industries. with the covid- pandemic and the drastic reduction of international and mainland tourism, the impact on the economy is yet to be fully revealed. due to the poor global economic outlook, unemployment is going to be increasing at an alarming rate, which will certainly have a negative impact on the number of cssa recipients. unfortunately, in the last few years the propensity to leave cssa is decreasing, creating an increased proportion of individuals being kept in cssa. hence, cssa has become somewhat of an ineffective crutch for these individuals, and the reliance on aid that is only intended to be transitional continues to leave a large proportion of beneficiaries feeling defeated and morally degraded . it is crucial to help those who are working to stay in work, otherwise even a small percentage change to the large overall working population will have a substantial impact on the number of cssa recipients. at the same time, by providing a reasonable wage it will also be able to retain/attract more people to joining the work force. trends in child poverty in hong kong immigrant families the hong kong federation of young groups. encouraging young-olds employment. government of hong kong special administrative region the common welfare: hong kong's social services components of a difference between two rates trends in elderly poverty in hong kong: a decomposition analysis explaining attitudes toward immigrants from mainland china in hong kong social security inequality and the third world determinants of poverty and their variation across the poverty spectrum: evidence from hong kong, a high-income society with a high poverty level government of hong kong special administrative region. hong kong poverty situation government of hong kong special administrative region. hong kong poverty situation the strategy of preventive medicine a review of the child care support for hong kong. social welfare department of the hong kong sar government optimal strategies for reducing number of people in the social security system a markov chain model for studying suicide dynamics: an illustration of the rose theorem assessing the impact of population dynamics on poverty measures: a decomposition analysis acknowledgements the authors are grateful to many useful comments from the two reviewers and the data made available by mr andrew kwan of the census and statistics department of the hong kong sar government. paul yip is a chair professor (population health) of the department of social work and social administration, the associate dean (research) of the faculty of social science, the founding director of the centre of suicide research and prevention at the university of hong kong. he served as the chairman of the committee of preventing students' suicide in hong kong and a member of the steering committee on population policy and an associate member of the central policy unit of the hong kong sar government. he is a recipient of a medal of honor (mh) of the hong kong sar government, the stengel research award, outstanding supervisor and researcher, knowledge exchange award of the university of hong kong; a distinguished alumnus of la trobe university, australia. he has published more than research papers relating to population health and suicide prevention. mr. so's research is devoted to studying the analysis of singular partial differential equations, treating the lie groupoid defining them as the fundamental object. this novel viewpoint brings many open questions, some of them are currently under intense investigation. he also has interests in applying mathematical tools in solving real life problems. phd in actuarial science from the university of hong kong. he is a fellow of the society of actuaries, a fellow of the actuarial society of hong kong, a chartered enterprise risk analyst and a certified financial risk manager. he is currently a lecturer at the university of hong kong. he teaches courses mainly targeting risk management and statistics students in the department of statistics and actuarial science, aspiring to demonstrate to students the rigor and usefulness of quantitative analysis from theory to practice. key: cord- -jtvf r authors: liao, qiuyan; cowling, benjamin j; lam, wendy wt; ng, diane mw; fielding, richard title: anxiety, worry and cognitive risk estimate in relation to protective behaviors during the influenza a/h n pandemic in hong kong: ten cross-sectional surveys date: - - journal: bmc infect dis doi: . / - - - sha: doc_id: cord_uid: jtvf r background: few studies have investigated associations between psychological and behavioral indices throughout a major epidemic. this study was aimed to compare the strength of associations between different cognitive and affective measures of risk and self-reported protective behaviors in a series of ten cross-sectional surveys conducted throughout the first wave of influenza a/h n pandemic. methods: all surveys were conducted using questionnaire-based telephone interviews, with random digit dialing to recruit adults from the general population. measures of anxiety and worry (affective) and perceived risk (cognitive) regarding a/h n were made in serial surveys. multivariate logistic regression models were used to estimate the cognitive/affective-behavioral associations in each survey while multilevel logistic models were conducted to estimate the average effects of each cognitive/affective measure on adoption of protective behaviors throughout the ten surveys. results: excepting state anxiety, other affective measures including “anticipated worry”, “experienced worry” and “current worry” specific to a/h n risk were consistently and strongly associated with adoption of protective behaviors across different survey periods. however, the cognitive-behavioral associations were weaker and inconsistent across the ten surveys. perceived a/h n severity relative to sars had stronger associations with adoption of protective behaviors in the late epidemic periods than in the early epidemic periods. conclusion: risk-specific worries appear to be significantly associated with the adoption of protective behaviors at different epidemic stages, whereas cognitive measures may become more important in understanding people’s behavioral responses later in epidemics. future epidemic-related psycho-behavioral research should include more affective-loaded measures of risk. understanding relationships between psychological state and protective behaviors during respiratory infectious disease epidemics (rides) can inform risk communication and interventions addressing behavior change [ , ] . studies of behavioral change during rides usually assess risk perception as an affect-neutral cognitive ("cognitive") process, commonly using measures such as perceived personal probability of infection or perceived severity of the illness [ ] [ ] [ ] , or as a more affect-active process, by assessing worry and anxiety [ ] [ ] [ ] [ ] [ ] . the latter are frequently referred to as "affective" dimensions of risk, though worry is often considered a cognitive dimension of anxiety [ ] . the dual-process theory proposes that responses to external stimuli involve two different processing systems, one being deliberate, slow and rule-based, the other being experiential, quick and intuitive [ ] . these two systems may reflect distinct response pathways to risk: risk-asanalysis (cognitive estimates) and risk-as-feeling (affective estimates) [ ] . the affect heuristics and risk-as-feeling hypotheses imply that affect quickly and more efficiently guides cognitive risk analysis and behavior [ ] [ ] [ ] . previous studies found that in the ride situation when personal threat is highly uncertain, affective measures of risk more powerfully predict protective behavior uptake than do cognitive measures [ , ] . therefore, both cognitive and affective components of risk appear to be relevant to understanding rides-related population behavior [ ] . in the early epidemic stage when uncertainty about the epidemic characteristics, treatment and prevention is higher, affective responses may be optimal for guiding behavioral change [ , , ] but cognitive risk responses should increasingly drive behavior as the epidemic evolves. we term these "psycho-behavioural" associations. given this, the question arises: should studies or assessments done early in the epidemic emphasize affect-based assessments of risk, whereas those performed later in the epidemic emphasize cognitive-based measures, in order to optimally predict behaviors? otherwise, it is possible that research conducted in different stages of an epidemic may observe different strengths for the same psycho-behavioral association and misattribute these. observed variation in the strength of specific psycho-behavioral associations across an epidemic introduces avoidable measurement error in the target cognitive/affective measure which will subsequently influence its association with behavioral change, reducing the apparent reliability of risk assessments as predictors of behavior change during rides. this raises questions about whether the same or similar associations would be repeatedly identified in surveys conducted in different epidemic periods within the same population. however, very few studies appear to have examined the consistency of these psycho-behavioral associations across different ride stages [ ] . we therefore performed secondary data analyses for data collected in a series of ten consecutive cross-sectional surveys spanning the epidemic wave of pandemic influenza a/h n in hong kong [ ] . the objectives of this study were to compare the strength and stability of associations between affective and cognitive measures of risk and the adoption of ride-related health protective behaviors. this was assessed by comparing the associations between health protective behaviors against a/h n and different cognitive/affective measures of risk used for each of the ten cross-sectional surveys. most psycho-behavioral studies of new communicable respiratory disease outbreaks were rapidly implemented [ ] . consequently, many used unrefined questionnaires, with several suffering from minimal theoretical support for the inclusion of specific psychological variables, items of limited utility in understanding behavioral change or items that may have posed task difficulty for respondents [ , ] , and multiple items, which increase interview load, thereby reducing interview efficiency and the accuracy of results. to inform future item selection, we therefore also sought to assess the difficulty respondents faced in answering different question measures of risk perception. this was done by examining proportions of missing data for different psychological measures as an indirect reflection of task difficulty. our null hypotheses were: . cognitive and affective measures of risk will not differ in terms of stability of association with adoption of protective behaviors across the ten cross-sectional surveys; . for the same associations measured at different epidemic periods, strength of associations between affective/cognitive measures and adoption of health protective behaviors will not decline/increase across epidemic stage; . there will be no difference in proportions of missing data for cognitive estimation items such as estimates of the likelihood of contracting influenza infection than other risk assessment formats reflecting no differences in the difficulties posed to respondents by such items [ , ] . between april and november , we monitored population psycho-behavioural responses to the influenza a/h n pandemic using cross-sectional surveys (s -s ) covering the entire first wave of the a/h n pandemic in hong kong [ ] . during the survey period, approximately % of the hong kong population were infected with this new virus [ ] . here we report data from of these (s -s and s -s ). the first two surveys (s and s ) conducted between april and may were excluded from this study because of incompatibility with later surveys and because the local a/h n epidemic did not start until s was conducted. survey s was excluded because of sample insufficiency. all surveys utilized identical methods involving random household telephone interviews based on randomly computergenerated landline telephone numbers of all hong kong households. one adult aged or above within each household was randomly selected based on a kish grid and invited for the telephone interview. sampling details have been published elsewhere [ ] . the study received ethical approval from the institutional review board (irb) of the university of hong kong. the irb waived written informed consent in lieu of verbal consent given the format of these ten telephone surveys. all participating respondents gave verbal consent for telephone interviews. the sample sizes for each of the ten surveys (s -s , s -s ) ranged between , - , , with response rates of . %- . % [ ] . surveys were conducted every two weeks with data collection completed within - days for each survey. the ten surveys covered different a/h n epidemic stages in hong kong. specifically, s (jun - , ) was conducted when local a/h n human cases were first identified in hong kong; s (sep [ ] [ ] [ ] [ ] ) was conducted when the local epidemic reached peak activity and s (nov - , ) when epidemic activity had declined substantially (additional file : figure s ). core items for the questionnaires used in the ten surveys were retained throughout. minor changes were made on one measure of risk perception (the comparator "perceived relativesusceptibility relative to others" was made more precise by specifying age and gender at s ) and two new items (current worry and infectivity relative to seasonal flu) were added in later surveys to refine measurement and during the surveys. table details psychological measures associated with risk covered by different survey periods. four measures (state anxiety, anticipated worry, experienced worry and current worry about a/h n infection) were classified as affective measures. four other measures (perceived absolute susceptibility and perceived relative susceptibility to a/h n infection, perceived a/ h n severity relative to sars and perceived a/h n infectivity relative to seasonal influenza) were classified as cognitive estimates of risk. the definitions, questions and response scales for these measures are detailed below and in the additional file : table s . respondents' anxiety level was assessed with a previously validated state-anxiety scale of the state-trait anxiety inventory (stai) wherein respondents' rate their feelings in response to ten general statements [ , ] . positive feeling statements were reversely coded and then the mean scores of the ten items (possible range - ) were calculated for subsequent analyses to overcome the problems of randomly missing items. (additional file : table s ). respondents were asked to rate their worry about possibly developing a/h n symptoms within the next hours (additional file : table s ). hence this measure was prospective. respondents were asked to recall whether they had experienced any worry over the past week about contracting a/h n (additional file : table s ). this measure was retrospective. starting from survey ( table ) respondents were asked about their current level of worry related to a/h n (additional file : table s ). this measure was current. respondents estimated their personal likelihood of contracting a/h n in the coming months throughout the ten surveys (additional file : table s ). this measure was prospective. in the earlier surveys, respondents estimated their personal likelihood of contracting a/h n relative to another table psychological measures and their proportions of missing data throughout the surveys s s s s s s s s s s missing rang% c totally missing% note "√" indicates that the measure was covered in the survey. a the measure of anxiety state included ten items asking about ten general feeling statements and thereby the proportions of missing data for anxiety in the table were the highest proportion of missing data of the item among the ten statement items. b these two items were combined as "perceived relative susceptibility" in the analysis. c the range of missing proportions across the covered surveys. (unspecified) person in the general population. in later surveys (s -s ), this item was slightly changed to personal likelihood of contracting a/h n relative to another person of similar age and sex in the general population (additional file : table s ). perceived a/h n severity relative to sars throughout the selected surveys, respondents estimated the perceived severity of a/h n infection relative to sars (additional file : table s ). starting from survey (table ) , this item was added in the surveys to assess the infectivity rate of a/h n relative to seasonal influenza, serving as an additional measure to assess the perceived severity of a/h n . the frequencies of three protective behaviors against a/h n were polled throughout the ten surveys. these were avoiding crowded places, maintaining good indoor ventilation and disinfecting the household frequently. all three protective measures were recommended by the hong kong government to minimize the transmission of influenza during the epidemic [ ] . respondents were asked whether they had adopted any of these three protective behaviors over the past seven days, and if so, whether the behaviors were adopted for a/h n prevention. these behavioral outcomes were dichotomized as " " (adopted for preventing a/h n ) and " " (not adopted or adopted for reasons other than preventing a/h n ) for subsequent analyses. previous analyses showed trends for psycho-behavioral associations were similar across the responses range on all the above risk measures [ ] . therefore, these responses were dichotomized as either above or below a threshold for subsequent analyses in order to facilitate comparison, and the process detailed in the additional file : table s . first, the proportions of missing data for all psychological measures associated with risk were calculated. then, multiple imputation was used to generate ten values for each missing value, the mean of which was substituted for the missing value. for each survey, one multiple logistic regression model calculated the associations between each of three protective behaviors (avoiding crowded places, maintaining good indoor ventilation and disinfecting household frequently) and each psychological variable (psycho-behavioral association) plus the corresponding % confidence interval. the psychobehavioral association was adjusted for respondents' age, gender, education, marital status and birth place in each logistic regression model because all these demographics are potential confounders of these psycho-behavioral associations [ ] . i (an index of variability) based on q-statistic was calculated to quantify heterogeneity of these psycho-behavioral associations across the ten surveys and to determine the appropriateness of combining the data from ten surveys to calculate averaged effects. i produces values ranging between and %, indicating the percentage of the total variation across surveys due to heterogeneity rather than chance [ ] . values of %, % and % arbitrarily indicate low, medium and high heterogeneity, respectively [ ] . all studied psycho-behavioral associations had either low or low-medium heterogeneity except that the associations between experienced worry and disinfecting the household frequently and between perceived severity relative to sars and disinfecting the household frequently had medium-tohigh heterogeneity across the ten surveys. therefore, random-effect multilevel logistic regression models were used to estimate the pooled effect of each psychobehavioral association across the ten surveys. for these multilevel models, individual responses were specified as the first level while survey periods were specified as the second level. all multilevel logistic regression models were adjusted for age, gender, education, marital status and place of birth. to minimize potential interactions (moderation or mediation) between different psychological measures [ , ] , only one psycho-behavioral association was assessed in each model. all analyses were conducted based on data excluding the small proportions ( . %- . %) of subjects who reported having had influenza-like illness (ili: fever plus cough or sore throat) within the two weeks prior to each survey. p-values < . were considered to be statistically significant. all analyses were conducted using stata software (version . ; stata corp., college station, tx). the ten surveys included a total of , subjects after excluding ( . %) subjects with ili. the effect sizes for differences between the sample characteristics (age, gender, education and place of birth) of each survey and the hong kong population were small, indicating good sample representativeness [ ] . missing data for the risk-related psychological measures table reports the proportions of missing data for each psychological measure and survey. among all the measures, perceived absolute susceptibility and perceived relative susceptibility to a/h n infection had the highest proportions (totally missing . % and . %, respectively) of missing data throughout the surveys, followed by perceived a/h n infectivity relative to seasonal influenza ( . %) and perceived a/h n severity relative to sars ( . %). affective measures generally had few missing data (below %, table ). figures , and show forest plots describing the associations of different risk-related psychological measures with avoiding crowded places (figure ) , maintaining good indoor ventilation ( figure ) and household disinfection (figure ) , respectively, throughout the ten surveys. the patterns of psycho-behavior associations were similar for the three types of health protective behaviors. for each of the three figures, the upper four forest plots illustrate the associations between affective measures and adoption of protective behaviors while the lower four illustrate the associations between cognitive measures and adoption of protective behaviors. averaged effects of different perceptions on adoption of each of the three protective behaviors are indicated by the lower diamond of each forest plot and in table . overall, all risk-related psychological variables were positively and significantly associated with all three heath protective behaviors except for the association between perceived absolute susceptibility and household disinfection ( table ) . figures , and suggest that all affective measures excepting state anxiety are more strongly associated with adoption of protective behaviors than are cognitive measures, these associations being consistently positive and statistically significant across the ten surveys. in particular, current worry and experienced worry had the strongest associations with adoption of protective behaviors among the eight risk-related psychological measures. state anxiety was only significantly associated with avoiding crowds in s and s (figure ) , with maintaining good indoor ventilation in s (figure ) , and with household disinfection in s , s , s and s (figure ). perceived absolute susceptibility was only weakly and significantly associated with avoiding crowds in s and s ( figure ) and maintaining good indoor ventilation in s , s and s (figure ) but not with household disinfection across the ten surveys ( figure ). perceived relative susceptibility seemed to have stronger associations with avoiding crowds and household disinfection than did perceived absolute susceptibility (figures and ) . no change was seen in associations between perceived relative susceptibility compared to another person, and adoption of protective behaviors in s -s when the refined measure of perceived relative susceptibility specified "a general person of similar age and gender". perceived higher a/h n severity relative to sars was more likely to be significantly associated with adoption of protective behaviors in later (s -s ) than earlier surveys, a pattern not found for other cognitive measures (figures , and ) . perceived a/h n infectivity relative to seasonal influenza was generally significantly associated with adoption of health protective behaviors but the associations were relative weaker than the associations between perceived a/h n severity relative to sars and adoption of health protective behaviors (figures , and ). our findings were mostly consistent with those hypothesized and the null hypotheses were largely rejected. the main finding is that affective measures of risk perception generally had stronger associations with reported adoption of health protective behaviors during the a/h n pandemic than did cognitive measures. this finding is consistent with those from other studies conducted during both sars [ ] and pandemic a/h n [ , ] , suggesting that affective components contribute significantly to adoption of protective behaviors in response to the threat during epidemics over and above simpler cognitive risk estimates. while previous studies were mainly conducted in early epidemic periods [ , ] , this study examined affectivebehavioral associations across the entire epidemic wave of a/h n in hong kong and found that the association between affect-loaded risk measures and adoption of protective behaviors were consistently strong and positive across different epidemic periods. studies of the anxiety-behavior association throughout the sars epidemic found consistently significant and positive associations during the early epidemic phase surveys but mostly non-significant associations in late epidemic phase surveys [ ] . the present study did not duplicate this pattern for any of the four affective measures. reported anxiety level was inconsistently associated with adoption of health protective behaviors in these surveys. one possible reason could be that the measure we used assessed general anxiety only rather than anxiety specific for a/h n . furthermore, overall reported state anxiety levels remained quite stable and consistently low throughout the a/h n epidemic [ ] , indicating a floor effect, suggesting that a low level of anxiety has little effect on these behaviors. other affective measures including anticipated worry, experienced worry and current worry generally involve less intense affective components compared with anxiety and thereby are more likely to covary with behavioral change. in particular, our study found that experienced worry and current worry seemed to have stronger associations with adoption of protective behaviors than did anticipated worry. one possible reason could be that the actual affective experience or associated processing may be more strongly associated with behavioral change than its anticipation, which may be subject to forecasting errors [ ] . cognitive risk assessments, in particular perceived susceptibility to a/h n (either absolute or relative susceptibility) had weak associations with adoption of protective behaviors. this suggests that cognitive-behavioral models such as the health belief model [ , ] that rely primarily on purely cognitive estimates of risk to predict behavioral change should perform relatively more poorly at predicting the adoption of protective behaviors during rides. cognitive-behavioral models generally assume rational processing of external information to inform action. however, during rides particularly in the early stages, uncertainty is usually widespread and poses high [ ] or ambiguous personal threat. consequently, people may face difficulties when attempting to quantify the probabilities of their risk of acquiring the infection and the severity of associated disease. whether it is threat ambiguity, task difficulty in determining risk magnitude or a primary affective response that modifies cognition, that leads to affect-related measures dominating remains unclear. this study found that the proportions of missing data for purer cognitive risk perception measures, particularly perceived absolute/relative susceptibility to a/h n were greater than for affect-loaded measures, suggesting that respondents may face greater figure associations between psychological responses and disinfecting household frequently during a/h n pandemic. task difficulties in comprehension and/or responses to such questions under epidemic circumstances. further study is needed to confirm the extent of this effect. perceived relative susceptibility seemed to have stronger associations with adoption of protective behaviors than perceived absolute susceptibility. perceived susceptibility measured in this relative way involves social comparison and accommodates the influences of optimistic bias [ ] and therefore probably involves more cognitive processing. more cognitive processing is associated with greater risk estimates and psychological distress [ ] . this might account for the more substantial associations with behavioral change than seen for simple personal risk estimates. associations between cognitive risk perception measures and protective action were quite inconsistent across the ten selected surveys in this study. previous reviews concluded associations between cognitive risk perception and adoption of protective behaviors during rides were inconsistent [ ] . our evidence suggests a major reason for this inconsistency lies in these studies being conducted in different epidemic stages [ , , ] . our hypothesis was that cognitive factors were more important in changing human behaviors in the later epidemic stage when people had more knowledge and less uncertainty about the threat. this study found that the associations between perceived a/h n severity relative to sars and adoption of each of the three protective behaviors became significantly and consistently positive starting from survey after the a/h n case confirmations had peaked, consistent with our hypothesis. however, this pattern of associations was not found for perceived susceptibility. perceived a/h n infectivity relative to seasonal flu, though not measured before survey s had weaker associations with adoption of health protective behaviors, than did perceived a/h n severity relative to sars in each survey and overall. however, these two measures assessed different aspects of a/h n severity with the former focused on the infectivity rate of a/ h n while the latter may primarily focus on the fatality rate of a/h n . further study is needed to confirm which aspects of disease severity could be more important in motivating behavior change. study limitations include the serial cross-sectional design and thereby reverse-causality remains a possible explanation. nonetheless, it is difficult to think of plausible mechanisms whereby, for example, disinfecting one's home will lead to greater worry regarding infection. alternatively, the associations could be spurious but this is unlikely given the consistent pattern of the associations in separate samples. it therefore seems most likely that the protective behaviors are consequential on the risk perceptions, and not vice versa. examining psychobehavioral associations using longitudinal data during rides is difficult due to their often-rapid evolution and the short lead-time compared to the need to obtain and retain large cohorts for follow-up surveys. conducting a series of consecutive cross-sectional surveys to investigate the psycho-behavioral associations is a better option than using a single cross-sectional survey. there may be concerns about the generalizability of our findings to more severe rides. for example, during the initial phase of the sars epidemic, population state anxiety regarding the epidemic was much higher and thereby had strong association with protective behavioral change [ ] . however, sars was the first of the new wave of rides, and a degree of risk fatigue may have subsequently set in. considering the common situation during rides, we believe that most of the findings in this study could be all data represent odds ratios and their corresponding % confidence intervals (in parentheses). all odds ratios were adjusted by age, gender, education, marital status and birth place. **p< . ; *** p < . . applicable in other rides. finally, because all data were self-reported the results may reflect social desirability bias. this study raises important implications for future respiratory communicable disease-related psycho-behavioral research and public health interventions. first, affective responses improve understanding of behavioral responses throughout different ride periods and must form part of measures in relevant studies. however, intense but nonspecific affect such as generalized state anxiety is probably less useful for understanding public behavioral responses during most epidemics where perceived milder threat fails to arouse such affect. less intense, specific affective responses to a identifiable, if uncertain threat that currently activates or has in the past activated worry may be more likely to show strong and consistent effects on behavioral change across different epidemic periods. second, cognitive risk estimates during the early epidemic stage may be poor at predicting human behavioral change and present task difficulties to respondents. however, cognitive risk estimates may inform individual behavioral change later in the ride epidemic trajectory and should be included in studies conducted during these phases. relative measures of perceived susceptibility appear superior to perceived absolute susceptibility in predicting behavioral change and thereby are preferable where questionnaire brevity is an issue. from a public health perspective, recognizing that the public may not show expected "rational" behaviors during rides is important. therefore, risk probabilities alone are unlikely to be sufficient to motivate protective behaviors. what affective strategies to use to best motivate behavioral change awaits clarification. risk perceptions related to sars and avian influenza: theoretical foundations of current empirical research demographic and attitudinal determinants of protective behaviours during a pandemic: a review an outbreak of the severe acute respiratory syndrome: predictors of health behaviors and effect of community prevention measures in hong kong, china factors influencing the wearing of facemasks to prevent the severe acute respiratory syndrome among adult chinese in hong kong pandemic influenza in australia: using telephone surveys to measure perceptions of threat and willingness to comply longitudinal assessment of community psychobehavioral responses during and after the outbreak of severe acute respiratory syndrome in hong kong initial psychological responses to swine flu public perceptions, anxiety, and behaviour change in relation to the swine flu outbreak: cross sectional telephone survey situational awareness and health protective responses to pandemic influenza a (h n ) in hong kong: a cross-sectional study the association between pandemic influenza a (h n ) public perceptions and reactions: a prospective study worry: a cognitive phenomenon intimately linked to affective, physiological, and interpersonal behavioural processes the self-regulation of health and illness behaviour risk as analysis and risk as feelings: some thoughts about affect, reason, risk, and rationality the affect heuristic risk as feelings community psychological and behavioral responses through the first wave of the influenza a(h n ) pandemic in hong kong risk perceptions: assessment and relationship to influenza vaccination risk perception measures' associations with behavior intentions, affect, and cognition following colon cancer screening messages epidemiological characteristics of (h n ) pandemic influenza based on paired sera from a longitudinal community cohort study state trait anxiety inventory: a test manual/test form center for health protection hong kong government: general guideline: a guide to personal, home and environmental hygiene: keep clean be healthy measuring inconsistency in meta-analyses emotions and preventive health behavior: worry, regret, and influenza vaccination avoidance behaviors and negative psychological responses in the general population in the initial stage of the h n pandemic in hong kong the health belief model and personal health behaviour the health belief model in the prediction of dietary compliance: a field experiment do moderators of the optimistic bias affect personal or target risk estimates? a review of the literature the function of credibility in information processing for risk perception factors associated with uptake of vaccination against pandemic influenza: a systematic review a tale of two cities: community psychobehavioral surveillance and related impact on outbreak control in hong kong and singapore during the severe acute respiratory syndrome epidemic the impact of community psychological responses on outbreak control for severe acute respiratory syndrome in hong kong anxiety, worry and cognitive risk estimate in relation to protective behaviors during the influenza a/h n pandemic in hong kong: ten cross-sectional surveys additional file : figure s . the a/h n pandemic curve in hong kong and timeline of the surveys.additional file : table s . questions for measuring anxiety, worry and risk perception in the study and their associated response scales. the authors declare that they have no competing interests.authors' contributions ql participated in the study design, analyzed the data, interpreted the data and drafted the manuscript. bjc supervised the research, contributed to study design, data interpretation and amended the manuscript. wwtl contributed to study design, data interpretation and amended the manuscript. dwmn contributed to questionnaire design, coordinated data collection and amended the manuscript. rf conceived of the study, designed the questionnaire, interpreted data and amended the manuscript. all authors read and approved the final manuscript. key: cord- - pxdeva authors: nicholson, karl g; wood, john m; zambon, maria title: influenza date: - - journal: lancet doi: . /s - ( ) - sha: doc_id: cord_uid: pxdeva although most influenza infections are self-limited, few other diseases exert such a huge toll of suffering and economic loss. despite the importance of influenza, there had been, until recently, little advance in its control since amantadine was licensed almost years ago. during the past decade, evidence has accrued on the protection afforded by inactivated vaccines and the safety and efficacy in children of live influenza-virus vaccines. there have been many new developments in vaccine technology. moreover, work on viral neuraminidase has led to the licensing of potent selective antiviral drugs, and economic decision modelling provides further justification for annual vaccination and a framework for the use of neuraminidase inhibitors. progress has also been made on developing near-patient testing for influenza that may assist individual diagnosis or the recognition of widespread virus circulation, and so optimise clinical management. despite these advances, the occurrence of avian h n , h n , and h n influenza in human beings and the rapid global spread of severe acute respiratory syndrome are reminders of our vulnerability to an emerging pandemic. the contrast between recent cases of h n infection, associated with high mortality, and the typically mild, self-limiting nature of human infections with avian h n and h n influenza shows the gaps in our understanding of molecular correlates of pathogenicity and underlines the need for continuing international research into pandemic influenza. improvements in animal and human surveillance, new approaches to vaccination, and increasing use of vaccines and antiviral drugs to combat annual influenza outbreaks are essential to reduce the global toll of pandemic and interpandemic influenza. influenza viruses have segmented genomes and show great antigenic diversity. of the three types of influenza viruses-a, b, and c-only types a and b cause widespread outbreaks. influenza a viruses are classified into subtypes based on antigenic differences between their two surface glycoproteins, haemagglutinin and neuraminidase. haemagglutinin subtypes (h -h ) and nine neuraminidase subtypes (n -n ) have been identified for influenza a viruses (figure ). viruses of all haemagglutinin and neuraminidase subtypes have been recovered from aquatic birds, but only three haemagglutinin subtypes (h , h , and h ) and two neuraminidase subtypes (n and n ) have established stable lineages in the human population since . only one subtype of haemagglutinin and one of neuraminidase are recognised for influenza b viruses. although most influenza infections are self-limited, few other diseases exert such a huge toll of suffering and economic loss. despite the importance of influenza, there had been, until recently, little advance in its control since amantadine was licensed almost years ago. during the past decade, evidence has accrued on the protection afforded by inactivated vaccines and the safety and efficacy in children of live influenza-virus vaccines. there have been many new developments in vaccine technology. moreover, work on viral neuraminidase has led to the licensing of potent selective antiviral drugs, and economic decision modelling provides further justification for annual vaccination and a framework for the use of neuraminidase inhibitors. progress has also been made on developing near-patient testing for influenza that may assist individual diagnosis or the recognition of widespread virus circulation, and so optimise clinical management. despite these advances, the occurrence of avian h n , h n , and h n influenza in human beings and the rapid global spread of severe acute respiratory syndrome are reminders of our vulnerability to an emerging pandemic. the contrast between recent cases of h n infection, associated with high mortality, and the typically mild, self-limiting nature of human infections with avian h n and h n influenza shows the gaps in our understanding of molecular correlates of pathogenicity and underlines the need for continuing international research into pandemic influenza. improvements in animal and human surveillance, new approaches to vaccination, and increasing use of vaccines and antiviral drugs to combat annual influenza outbreaks are essential to reduce the global toll of pandemic and interpandemic influenza. we reviewed international reports published in english before december, . the data for this non-systematic review of articles were identified by searches of medline, embase, integrated science citation index, pubmed, and the cochrane library electronic databases with relevant keywords. we also searched cited references in retrieved articles, reviewed articles we have collected over many years, referred to the textbook of influenza, and used knowledge of new data presented at international scientific meetings. because of the large number of articles that are published every year and limitations on the number of citations, we gave emphasis to clinically relevant issues, particularly disease burden, the emergence of new subtypes, vaccines, and antivirals, and diagnosis. we gave priority to randomised controlled trials when available, to larger studies, articles published in high-impact journals that have a wide readership, and the systematic review and economic decision modelling, for the prevention and treatment of influenza, commissioned by the health technology assessment programme on behalf of the national institute of clinical excellence. we also drew on our own knowledge when it seemed appropriate to fill in the gaps in the published work and included several recent pertinent articles. haemagglutinin facilitates entry of the virus into host cells through its attachment to sialic-acid receptors. it is the major antigenic determinant of type a and b viruses to which neutralising antibodies are directed and the crucial component of current influenza vaccines. an important function of neuraminidase, the second major antigenic determinant, is to catalyse the cleavage of glycosidic linkages to sialic acid, thereby assisting in the release of progeny virions from infected cells. accordingly, neuraminidase has become an important target for antiviral activity. the m ion channel of influenza a, which is blocked by the antiviral drug amantadine, regulates the internal ph of the virus, which is crucial during early viral replication. the epidemiological behaviour of influenza in people is related to the two types of antigenic variation of its envelope glycoproteins-antigenic drift and antigenic shift. during antigenic drift, new strains of virus evolve by accumulation of point mutations in the surface glycoproteins. the new strains are antigenic variants but are related to those circulating during preceding epidemics. this feature enables the virus to evade immune recognition, leading to repeated outbreaks during interpandemic years. antigenic shift occurs with the emergence of a "new", potentially pandemic, influenza a virus that possesses a novel haemagglutinin alone or with a novel neuraminidase. the new virus is antigenically distinct from earlier human viruses and could not have arisen from them by mutation (figure ). four or five pandemics of influenza occurred during the th century with intervals of - years. the h n pandemic of - was the most devastating, with - million deaths; an estimated · million excess deaths, representing % of the population, occurred in india alone. however, the cumulative mortality from influenza during the intervening years is generally many times greater than that associated with pandemics. although influenza a or b viruses circulate virtually every winter in temperate zones of the northern and southern hemispheres, quantification of the burden of influenza on consultations, emergency-department examinations, hospital admissions, and mortality has been difficult because influenza lacks pathognomonic features, it cocirculates with other respiratory pathogens, and it causes a range of nonspecific complications, such as exacerbations of chronic cardiopulmonary disease. nevertheless, there is much evidence that the h n subtype of influenza a virus causes more severe illness than h n or influenza b, - more hospital admissions for pneumonia and influenza, and higher numbers of excess deaths. during outbreaks, sentinel schemes, such as the royal college of general practitioners' network in england, report increased consultation rates for influenza-like illness and other respiratory syndromes that are strongly associated with excess mortality. in england and wales, an estimated - people died during each of the epidemics between - and - . these estimates are about ten times the number of death certifications for influenza, because the disease is the cause of many "hidden deaths". in the usa, during the about % of these influenzaassociated excess deaths are among people aged years and older. although there are age-related increases in deaths from influenzal illness in both at-risk and low-risk groups, most deaths and hospital admissions occur in elderly people with chronic cardiopulmonary disorders. among toddlers, rates of influenza-associated hospital admission in the usa have ranged from about per population for those with high-risk conditions to per for those without high-risk conditions. [ ] [ ] [ ] [ ] admission rates are highest among children younger than year and are similar to rates found among people aged years and older. , among children in hong kong, china, the numbers of excess hospital admissions attributed to influenza are very high in children younger than months ( and per in and , respectively) and decrease with age ( and per children aged - months; and per children aged - years; and per children aged - years; and and per children aged - years). in the tropics and subtropics, influenza occurs either throughout the year with no distinct seasonality or visible excess mortality, or twice a year, with the more intense activity during the rainy season. consequently, the morbidity and mortality from influenza are probably greatly underestimated in these regions. during summer, , an epidemic of respiratory illness with cases and % case-mortality affected madagascar; it was attributable to influenza a/panama/ / -like (h n ) virus. the loss of life was greatest in young children and was ascribed to malnutrition and poor access to health care. another outbreak attributable to influenza a/panama/ / -like (h n ) virus occurred during november and december, , in the district of bosobolo, democratic republic of congo. the casefatality rate was · % in children younger than years and · % in people over . these rates illustrate the seriousness of such outbreaks and are one of the reasons why improved linkage of morbidity and mortality analysis with virological surveillance is one of the key objectives of the who global agenda on influenza, formulated in . in southern china, influenza viruses circulate throughout the year. there is evidence for the origin in china of the viruses that caused the pandemics of h n influenza in , h n influenza in , and the re-emergence of h n influenza in . recent outbreaks of avian influenza a h n and h n in people in hong kong show the importance of virological surveillance in this region for the early detection of potentially pandemic viruses. there is also evidence that some drift variants circulate in china for up to years before causing epidemics in europe and north america. , this region is thought to provide an appropriate ecological niche for the emergence of new influenza viruses with pandemic potential, owing to the proximity of dense populations of people, pigs, and wild and domestic birds, thereby facilitating genetic reassortment of viruses from different species (figure ), or for the emergence of drift variants, given the high human population density and year-round virus circulation. these observations provided the impetus for improving the who global influenza surveillance programme in china that has provided many of the vaccine strains recommended by who in the past decade. the examples cited below indicate the unpredictability of influenza-virus variation and the great capacity for evolution, but they also show that novelty alone is insufficient for the emergence of pandemic influenza. adaptation to replication in human beings, the ability to spread from person to person, and a susceptible population are also prerequisites. thus, the emergence of new influenza-virus variants in the human population does not necessarily herald pandemic influenza. influenza a/hong kong/ (h n ) in may and november-december, , cases of influenza h n infection were identified in people in hong kong. this outbreak, which followed serious outbreaks of avian h n influenza in chicken farms, signalled the possibility of an incipient pandemic. the human influenza isolates were of avian origin and were not derived by reassortment. the high mortality (six of patients died from acute respiratory distress syndrome or multiple organ failure, most previously healthy young adults ) suggested an unusually aggressive clinical course. deterioration was rapid, with pneumonia necessitating ventilatory support developing within a few days of illness onset. striking features of severe cases were the early onset of lymphopenia and high concentrations of serum transaminases. fortunately, there were few if any secondary infections, and the h n outbreak ceased when all chickens in hong kong (about · million) were slaughtered. the territory's poultry stocks were again depopulated when highly pathogenic a/hong kong/ (h n ) virus reemerged in flocks in may, , and february and april, . however, no further human cases of h n influenza were identified until february, , when two cases were confirmed in a family of hong kong residents. the first patient, a -year-old boy who was admitted to hospital in hong kong and recovered, became unwell during travel to fujian province, mainland china. the boy's -year-old father died in a hong kong hospital and his -year-old sister died in a hospital while the family was in china; the cause of her death is not known. genetic analysis of the two h n isolates showed that the virus genes were purely avian in origin, but differed from the strains that infected human beings. after the h n outbreak in hong kong, heightened surveillance in the adjoining guandong province led to recovery of nine human isolates of h n virus during july-september, . in march, , influenza h n viruses were isolated from two children in hong kong. the illness in both was mild and self-limited. no serological evidence of h n infection was found in family members or health-care workers who had close contact with the children; thus, h n viruses, like h n viruses, seem not to be easily transmitted from person to person. three lineages of h virus have been defined, with the prototype viruses being g , g , and y . the g "avian" h n viruses isolated from human beings have some receptor properties similar to those of other human viruses-ie, binding to ␣ , sialic acid linkages, in contrast to the binding preference to the ␣ , linkages normally found with avian influenza viruses. in hong kong, antibody to h viruses was found in about % of blood donors, which suggests that human infection with h n may occur in this locality. surveillance of pigs in southern china has shown that h n viruses are cocirculating with human a/sydney/ -like h n viruses and other porcine h n and h n viruses. together, these observations indicate that all the precursors of potentially pandemic h human-avian reassortants are in place. during february, , a new influenza h n virus was isolated from patients with influenza-like illness in england and the middle east. in the uk it affected mainly young children. these h n viruses arose after reassortment of the segments of the currently circulating influenza a (h n ) and a (h n ) subtypes. although influenza a (h n ) viruses have been identified previously, during - , when influenza a (h n ) viruses were isolated in six cities in china, the virus did not spread further. , the limited effect of h n in and during the - and - seasons is attributable to the good pre-existing immunity in the population. in , four people contracted purulent conjunctivitis within days of post-mortem examination of harbour seals that died during an outbreak of influenza a/seal/mass/ / (h n ), an a/fowl plague/dutch (h n )-like virus, in cape cod, ma, usa. subsequently, a/seal/mass/ / (h n ) was recovered from the conjunctiva of an investigator who developed conjunctivitis when an infected animal sneezed into his face. in , avian h n virus was isolated in the uk from a woman with conjunctivitis who kept ducks. although none of these six patients had respiratory symptoms, an outbreak of highly pathogenic avian h n influenza in poultry farms in the netherlands, which began at the end of february, , was associated with fatal respiratory illness in one of human cases by april . the person who died was a previously healthy -year old veterinary surgeon who developed severe headache, renal impairment, interstitial pneumonia, and acute respiratory distress after visiting an affected poultry farm. most patients presented with conjunctivitis (n= ), and only seven (< %) had respiratory illness. transmission of h n influenza from poultry workers to family members was found on three occasions. most virus isolates obtained from human beings had not accumulated significant genetic changes, including those from cases of human-to-human transmission. however, the virus isolated from the person who died had aminoacid substitutions, which suggests a role in pathogenicity. rapid, near-patient tests for influenza can aid clinical management, but the usefulness of existing tests for decisions on whether to start antiviral drug treatment is limited because they are complex or have low sensitivities (table ) . [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] however, rapid influenza tests can show whether virus is circulating in specific populations or localities, and they may become a useful adjunct to surveillance programmes. thus, treatment with anti-influenza drugs commonly depends on patients' symptoms. although influenza has no pathognomonic features, it was diagnosed correctly in clinical trials in about two-thirds of adults when the clinical entry criteria were met. cough and fever (temperature · °c or above) are the most predictive symptoms of influenza, but fever may not be present in elderly people. in primary care, about - % of patients with influenza-like illness have the disease during outbreaks. [ ] [ ] [ ] thus, optimum implementation of guidelines for antiviral treatment depends on continuous community-based clinical and virological surveillance and awareness by general practitioners that influenza is circulating. most of what we know about highly pathogenic influenza viruses derives from studies with avian influenza viruses in birds. this situation is potentially relevant to disease in human beings because some mechanisms of pathogenicity in birds may operate in mammals and new human influenza a strains may come ultimately from the avian reservoir. tissue tropism and the capacity for systemic spread are the most important determinants of pathogenicity in birds. the molecular correlates of these pathogenic properties reside in the viral haemagglutinin and have been well studied. [ ] [ ] [ ] however, in mammals, factors other than viral haemagglutinin are involved in determining pathogenicity, including viral non-structural protein , pb , and neuraminidase. recovery of nucleic acid of the pandemic virus from post-mortem tissue or preserved human remains has shown that this highly pathogenic virus did not have the molecular motifs in haemagglutinin associated with virulence in avian strains. , the use of reverse genetics techniques has allowed the direct manipulation of influenza-virus gene products and creation of new recombinant viruses. selective testing of specific mutations engineered into recombinant viruses in a mouse model has shown that greater virulence is obtained by specific molecular properties of haemagglutinin, but these do not fully explain pathogenicity. the balance between viral replication and host immune response determines the outcome of viral infection. highly virulent viruses, such as h n , have a remarkable capacity to resist the antiviral effects of host cytokines. infection of human macrophages also results in induction of high cytokine expression, suggesting that severe outcome of infection is due both to lack of inhibition of viral replication by cytokines and to excess induction of cytokines leading to tissue damage in the infected host. the key genetic component determining replication of highly pathogenic virus may be the nonstructural protein of the virus, which has been identified as the major immune modulator. factors contributing to the pathogenesis of influenza in people are incompletely understood. these include understanding of the nature of tissue restriction of proteases, differences in reactivity of the innate immune system at different stages of life, and varying susceptibilities in different human populations, leading to different ranges of disease in certain populations; for example, encephalopathy is well recognised in japan, but less so in other populations. , study of mechanisms of virulence should provide more than simply elucidation of pathogenesis, notably development of alternative means of attenuating influenza viruses (eg, by deletion of non-structural protein or m [matrix protein ] genes) to make safer vaccine strains. current vaccines are produced from virus grown in fertile hens' eggs and inactivated by either formaldehyde or ␤-propiolactone. they consist of whole virus, detergent-treated split product, or purified haemagglutinin and neuraminidase surface antigen formulations of the three virus strains currently recommended by who. about countries have government-funded national immunisation programmes, and influenza vaccine is available in many others. about million of the world's population of billion were vaccinated during . specific vaccine recommendations vary, but most involve annual vaccination of elderly people and those with certain chronic medical disorders. these recommendations were founded on proven morbidity and mortality in the at-risk groups, consistent demonstrations of vaccine efficacy in military recruits, recognition of the relation between antibody and protection, and proof of vaccine antigenicity. whole-virus vaccines are not widely available because they cause adverse reactions in young children, whereas split-product formulations and those containing purified surface antigen are well tolerated and extremely safe. the virtual absence of published reports suggests that hypersensitivity reactions are rare. recent randomised controlled trials efficacy and effectiveness of current vaccines studies on the efficacy and effectiveness of inactivated influenza vaccines reveal substantial benefits. in children, meta-analysis of double-blind - and singleblind , randomised controlled trials estimated the efficacy of vaccine in preventing symptomatic laboratory-confirmed influenza at % (table ) . other benefits include reductions in school absenteeism, otitis media, asthma exacerbations, and febrile respiratory illness in unvaccinated household contacts. , [ ] [ ] [ ] [ ] [ ] in adults of working age, meta-analysis of two randomised controlled trials of split influenza vaccines , estimated the efficacy in preventing laboratory-confirmed influenza at % (table ) . associated benefits include reductions in absenteeism, consultations, antibiotic use, and use of over-thecounter medication. [ ] [ ] [ ] the frequency of laboratory-confirmed influenza fell by % in vaccinees in a randomised controlled trial (table ) and by % in a prospective cohort study of elderly people living in the community. many cohort and case-control studies have shown lower rates of hospital admissions for pneumonia and influenza, - all respiratory disorders, , respiratory disorders and heart failure, deaths from pneumonia and influenza, , and all-cause mortality , , in vaccinees than in controls (table ) . a meta-analysis of reports published before showed that vaccination reduces numbers of cases of influenza-like illness by %, hospital admissions for pneumonia and influenza by %, and all-cause mortality by %. a prospective observational study of nursinghome residents in japan showed a % reduction in laboratory-confirmed influenzal illness among vaccinees. vaccination also reduced numbers of hospital admissions among vaccine failures and thus appears to ameliorate illness severity. gross and colleagues did a meta-analysis of cohort studies. the odds ratios for development of respiratory illness ( · ) or pneumonia ( · ), hospital admission ( · ), and mortality ( · ) indicate substantial protection. vaccination of elderly patients with chronic lung disease reduces hospital admissions for pneumonia and influenza by %, all-cause mortality by %, and complications (death, exacerbations of lung disease, pneumonia, heart failure, angina, and myocardial infarction) by %. influenza vaccination also prevents heart failure, brain infarction, recurrent myocardial infarction, and primary cardiac arrest, indicating important benefits in patients with cardiovascular disease. vaccination of patients with diabetes mellitus is associated with an estimated % reduction in hospital admissions, mostly ( %) for reasons of diabetic control. thus, influenza vaccine protects against several potentially fatal events that explain the many hidden deaths that accompany epidemics. staff have been implicated as the source of influenza in several outbreaks in nursing homes. accumulating that influenza vaccination of staff caring for elderly people in long-stay facilities provides benefits to residents. [ ] [ ] [ ] one study showed substantial herd immunity ( - % protection) among patients exposed to staff with high vaccine coverage. during the past decade, there have been many new developments in vaccine technology that have aided vaccine production or aimed to improve vaccine immunogenicity and acceptability. subunit influenza vaccine with adjuvant mf , an emulsion of squalene in water for parenteral use, is licensed in some european countries but not the uk. mf significantly increases haemagglutinationinhibition antibody responses to interpandemic influenza a h n and influenza b antigens, particularly in older people with chronic diseases, and is well tolerated despite slightly higher rates of transient mild local reactions than with other vaccines. virosomes consist of bilayers of phospholipids (liposomes) containing virus surface proteins embedded in the bilayer. virosomes have been extensively evaluated in various human populations. typically, virosomes induce higher concentrations of antibody after vaccination, higher rates of seroconversion, and a greater proportion of individuals with "protective" antibody titres than conventional inactivated vaccines. virosomal influenza vaccine for parenteral use became available in the uk during the - season. cell-culture vaccines offer the potential of being able to respond quickly to epidemics or a pandemic at any time of the year and avoid the risk of contaminated eggs, which could affect the bioburden and endotoxin content of vaccines. moreover, influenza viruses grown in mammalian cells more closely resemble those present in clinical samples than viruses isolated and grown in eggs, hence offering the potential for more effective vaccine. influenza vaccines prepared with madin darby canine kidney (mdck) and african green monkey (vero) cells as substrate have been licensed in the netherlands but are not yet available commercially. live attenuated influenza vaccines intranasal delivery of live influenza vaccines offers the advantage of mimicking natural infection, thereby providing a broader immunological response and more durable protection than with inactivated vaccines. strategies for use of live influenza vaccines based on the transfer of genes coding for cold adaptation (ca) and temperature sensitivity from an attenuated parental virus donor have been used in russia for many years and were approved in june, , by the us food and drug administration for use in healthy children and adolescents aged - years, and in healthy adults aged - years after three decades of clinical evaluation. vaccines based on ca replicate well at the temperatures found in the nasopharynx but not at temperatures in the lower airways. in young children, a recent study of us ca vaccine showed very high protection with benefits in terms of both influenzal illness and otitis media. during the second year of this study, ca vaccine afforded a high degree of protection against a variant not closely matched to the vaccine antigen. studies in nursing-home residents have suggested that a combination of live and inactivated influenza vaccines may improve protection in these communities. immunostimulating complexes are cage-like structures that were originally formed as a complex between cholesterol and saponin derived from the tree quillaia saponaria. vaccines containing a defined saponin called iscoprep stimulated an accelerated serum antibody response in human beings compared with conventional inactivated vaccines, an improved proliferative t-cell response, and a cytotoxic t-cell response. although nasally delivered influenza vaccine could greatly increase vaccine coverage and provide mucosal immunity, intranasal administration of conventional inactivated influenza vaccines has typically been unsuccessful. in animals, incorporation of a mucosal adjuvant derived from bacteria has been necessary to improve immunogenicity, and several such vaccines administered intranasally have been evaluated clinically, with promising results. an intranasal spray formulation containing trivalent subunit influenza vaccine prepared from virosomes and wild-type escherichia coli enterotoxin was licensed briefly in switzerland. although it met the immunogenicity criteria set for yearly relicensing of conventional influenza vaccines, it was withdrawn after a possible association with bell's palsy could not be discounted. various microparticles are being investigated as adjuvants and delivery systems, for parenteral delivery of influenza-virus antigens or delivery to mucosal sites including the gut. subunit influenza vaccines have been prepared from recombinant haemagglutinin and neuraminidase proteins expressed in insect cells by baculoviruses. the recombinant haemagglutinins are well tolerated by young adults and elderly people, and there are significant doseresponse effects for both h and h haemagglutinin vaccines. phase i and virus-challenge studies of baculovirus-expressed recombinant neuraminidase in healthy volunteers have had promising results. the development of reverse-genetics techniques for negative-sense rna viruses has allowed the direct manipulation of influenza-virus gene products and creation of new recombinant viruses. this approach offers enormous potential for preparing interpandemic vaccines. nucleic-acid vaccines dna vaccines present a promising new approach to vaccination, evoking a full range of immune responses, including antibody, cytotoxic, and helper-t-cell responses. dna vaccines with constructs encoding the nucleoprotein (np), haemagglutinin, neuraminidase, matrix protein (m ), and non-structural protein of influenza virus have been studied extensively, either singly, in combination with one another, or together with dna encoding various cytokines. currently, two drug classes are available to manage influenza: the inhibitors of m , amantadine and rimantadine, and the neuraminidase inhibitors, zanamivir seminar the lancet • vol • november , • www.thelancet.com and oseltamivir. rimantadine causes less neurotoxicity than amantadine but is not available in most parts of the world and is not discussed further. amantadine inhibits the m membrane protein ionchannel activity of the influenza a virus but has no effect on influenza b. amantadine has three important limitations: its range of activity excludes influenza b; it has adverse side-effects, including insomnia, lightheadedness, hallucinations, dizziness, headache, and falls, which are particularly troublesome in elderly people; and drug resistance emerges rapidly during treatment. the genetic basis of resistance is a single nucleotide change, resulting in an aminoacid substitution at position , , , , or in the membrane-spanning region of m . estimates of amantadine's therapeutic effectiveness are uncertain owing to the clinical and methodological heterogeneity of clinical trials, a paucity of data by dose, the small number of trials in children and elderly people, and low trial-quality scores. treatment of healthy adults with - mg daily of amantadine cuts the duration of fever compared with placebo by day. there are few data on use of the currently licensed dose in the uk, mg daily. at this dose, amantadine reduced the duration of fever compared with placebo by day, but in a meta-analysis of data from six trials involving a total of patients the effect did not attain statistical significance. there is no high-quality evidence from randomised controlled trials of the effectiveness of amantadine mg daily for the treatment of influenza in at-risk individuals, and illness was significantly shortened with treatment by · days in only one of two small randomised controlled trials in children. , no randomised trial has tested amantadine during outbreaks in nursing homes. moreover, its use in this setting is complicated by toxicity, treatment failures, and frequent recovery of drug-resistant virus (about %). amantadine prophylaxis of other populations during interpandemic outbreaks is precluded by the lack of high-quality evidence from randomised controlled trials at the licensed dose and the high incremental cost per quality-adjusted life-year gained. this second-generation neuraminidase inhibitor is a potent and specific inhibitor of a wide range of influenza virus types a and b. it has poor oral bioavailability and is delivered through an inhaler. zanamivir is licensed for the treatment of influenza a and b in people aged years and over. it is well tolerated; the number, type, and severity of adverse events in healthy adults or people with stable chronic underlying medical disorders differ little from those with placebo. the main safety concern is that inhaled zanamivir may cause bronchospasm. however, respiratory viruses including influenza regularly exacerbate asthma and chronic obstructive pulmonary disease, so the role of zanamivir in bronchospasm is unclear. zanamivir was administered with apparent safety in two studies involving patients with asthma or chronic obstructive pulmonary disease. , difficulty in using the inhaler may limit use of zanamivir. in one study, half of a very elderly group were unable to use the inhaler after training, and two-thirds zanamivir healthy individuals, aged - years · ( · to · ) · ( · to - · ) · (- · to · ) · ( · to · ) at-risk individuals, including older than years · (- · to · ) · ( · to · ) · (- · to · ) · (- · to · ) healthy children · ( · to · ) · ( · to · ) · (- · to · ) · (- · to · ) "all" individuals · ( · to · ) · ( · to · ) · ( · to · ) · ( · to · ) healthy individuals, aged - years · ( · to · ) · ( · to · ) · ( · to · ) · ( · to · ) at-risk individuals, including older than years Ϫ · (- · to · ) · (- · to · ) · ( · to · ) · ( · to · ) healthy children · ( · to · ) · ( · to · ) · ( · to · ) · ( · to · ) "all" individuals · ( · to · ) · ( · to · ) · ( · to · ) · ( · to · ) itt=intention-to-treat. were unable to use it the next day. however, in three other studies, it was used successfully by about % of more than elderly people. summary results, which draw from published [ ] [ ] [ ] [ ] [ ] [ ] and unpublished treatment studies with zanamivir, are shown in table . overall, symptoms were alleviated sooner with zanamivir than with placebo-a median of · days on an intention-to-treat basis and · days for the influenzapositive subgroup. with zanamivir, the median time to return to normal activities was · days shorter for the treatment group, for both the intention-to-treat and influenza-positive populations. in a pooled analysis of intention-to-treat data from trials including both otherwise healthy and at-risk individuals, antibiotics were given to a smaller proportion of patients receiving zanamivir than of those assigned placebo (table ). similar, but nonsignificant, reductions in need for antibiotics in high-risk individuals and in pneumonia were seen with treatment in published and unpublished marginal analyses. seasonal prophylaxis with zanamivir mg daily of mostly unvaccinated healthy adults provided an estimated % reduction in the incidence of laboratory-confirmed clinical influenza compared with placebo, and metaanalysis of two randomised controlled trials of postexposure prophylaxis, with treatment given for days or days, suggested % protection against symptomatic laboratory-confirmed influenza. oseltamivir this third-generation neuraminidase inhibitor is an orally active prodrug of oseltamivir carboxylate. it is licensed for the treatment of influenza a and b in people aged year or older and for the prophylaxis of influenza a and b in people aged years or older. the frequency of nausea is - % higher and of vomiting up to % higher than with placebo; , these gastrointestinal side-effects can be ameliorated if the drug is taken shortly after food. summary results, which draw from published [ ] [ ] [ ] and unpublished treatment studies with oseltamivir (table ) show that for all treatment groups combined, symptoms were alleviated sooner with oseltamivir than with placebo, by · days on the basis of intention to treat and · days for the influenza-positive subgroup. similarly, normal activities were resumed · days and · days sooner with oseltamivir for the intention-to-treat and influenzainfected group, respectively. treatment with oseltamivir reduces the frequencies of otitis media, antibiotic use, pneumonia, and hospital admissions. in children with influenza, the frequency of otitis media was % with placebo and % with oseltamivir. the rate of antibiotic use in the intention-totreat population in one study was · % (eight of ) with placebo and · % (one of ) with treatment. pooled marginal analyses showed lower rates of antibiotic use for lower-respiratory-tract complications in "healthy" and "high-risk" people with influenza with oseltamivir than with placebo; a lower frequency of pneumonia in the influenza-positive group of ten studies ( % among placebo recipients vs < % with oseltamivir; table ); and a significant reduction in the occurrence of hospital admissions in influenza-positive populations of ten trials ( · % vs · %). three different strategies in preventing laboratoryconfirmed symptomatic influenza with oseltamivir have been investigated in randomised controlled trials. metaanalysis of data from two trials of seasonal prophylaxis in non-vaccinated healthy adults with oseltamivir, mg once daily, gave an estimate of % protection. in households, postexposure prophylaxis with oseltamivir, mg once daily for days, gave % protection. similarly, seasonal prophylaxis of mostly vaccinated elderly people receiving residential care with oseltamivir, mg daily for weeks, provided % protection. resistance to neuraminidase inhibitors influenza viruses with low susceptibility to the neuraminidase inhibitors have been isolated in vitro and in vivo. resistance involves either a mutation in the active site of the neuraminidase, altering its sensitivity to inhibition, or a mutation in the haemagglutinin. mutations in haemagglutinin that confer drug resistance decrease the affinity of the protein for the cellular receptor, thus enabling virus to escape from infected cells without the need for viral neuraminidase. to date, few viruses with altered susceptibility to neuraminidase inhibitors have been recovered from patients. the first report of emergence of neuraminidaseinhibitor resistance (r k) during treatment with zanamivir involved a recipient of a bone-marrow transplant. during clinical trials with oseltamivir, · % (four of ) of post-treatment isolates from adults and adolescents and · % (nine of ) from children had low neuraminidase-inhibitor susceptibility, indicating that such viruses are likely to emerge in clinical practice. three resistant variants with neuraminidase mutations (e v, h y, and r k) that have emerged in clinical trials show low infectivity and virulence in animal models, thus the relevance of these mutations in clinical practice remains uncertain. in , an international neuraminidase susceptibility network was established to oversee global surveillance of neuraminidase-inhibitor resistance. the uk national institute for clinical excellence (nice) has recently issued new guidance on the interpandemic use of antivirals for the treatment of influenza. amantadine is not recommended. neither zanamivir nor oseltamivir is recommended for the treatment of influenza in children or adults unless they are at risk. within their licensed indications, zanamivir and oseltamivir are both recommended for the treatment of atrisk adults, and oseltamivir for the treatment of at-risk children, who present with influenza-like illness and can start therapy within h of the onset of symptoms, when it is known that influenza a or b is circulating in the community. nice guidance on the use of antiviral drugs for the prevention of influenza was also issued lately. oseltamivir is recommended for postexposure prophylaxis of influenza in at-risk people aged years and older, who can begin prophylaxis within h, if they live in a residential care establishment, whether or not they have been vaccinated, and a resident or staff member has influenza-like illness; or if they are not effectively protected by vaccination and can begin prophylaxis within h of exposure. oseltamivir is not recommended for postexposure prophylaxis of healthy people up to age years or for seasonal prophylaxis. amantadine is not recommended for either postexposure or seasonal prophylaxis. this guidance does not cover the circumstances of a pandemic. the hong kong "chicken flu" situation in and the rapid global spread of severe acute respiratory syndrome highlighted how ill prepared we are to introduce preventive measures for pandemic influenza. the problems encountered in were due mainly to the dangers of working with the chicken h n virus and the need to produce a safe vaccine strain. conventional technology was unable to produce a safe productive vaccine strain. however li and colleagues were able to modify the haemagglutinin gene of the a/hong kong/ virus. they deleted the series of basic aminoacid residues at the cleavage site associated with virulence, then by use of reverse genetics rescued the modified haemagglutinin gene and the neuraminidase gene from the wild-type a/hong kong/ virus into ca a/ann arbor/ / virus. the resultant ca virus was non-pathogenic in animal models of infection, grew well in eggs, and protected chickens from challenge with lethal virus; it could be a suitable candidate vaccine strain. these experiments show the potential for using reverse genetics technology to develop live and inactivated vaccines for both pandemic and interpandemic use. a second strategy for pandemic vaccine development is the use of recombinant haemagglutinin. however, the disappointing results from clinical trials of baculovirusexpressed haemagglutinin from the a/hong kong h n virus, even after two doses of up to µg, question the role of this strategy alone. clinical trials of conventional inactivated-surface-antigen vaccine produced from an h n virus showed that extremely poor antibody responses were stimulated, even after two doses, whereas an h n subunit vaccine with mf adjuvant was much more immunogenic. the benefit of adjuvants for use in naïve populations has also been shown with a whole-virus h n vaccine with aluminium salts adjuvant. thus, like mf , aluminium salts have promise in increasing vaccine coverage in response to pandemic influenza by allowing scarce antigen to be used more efficiently. from the limited information available, conventional influenza vaccines seem not to be sufficiently immunogenic in a pandemic situation and two doses in conjunction with an adjuvant may be needed. different dosing strategies with various influenza-virus subtypes should be investigated so a robust strategy can be developed. vaccines will be in very short supply during the first stages of a pandemic, and antiviral drugs could have an important role in prevention. who has recently prepared draft guidelines for use of both vaccines and antiviral drugs during a pandemic; they emphasise the need to stockpile drugs and to develop plans for their distribution and use. as with vaccines, there are gaps in our knowledge as to how antiviral drugs should be used. research is urgently required to ensure effective use of both vaccines and drugs in response to an emerging pandemic. kgn has received fees or honoraria from roche pharmaceuticals, wyeth, and berna biotech for speaking at meetings on influenza; research has been supported by chiron vaccines, aventis pasteur, wyeth, and berna biotech. solvay and berna biotech have provided h avian influenza viruses free of charge for a project on candidate pandemic vaccines. mz has received honoraria from berna biotech to speak at pharmaceutical-industry conferences on influenza and has been supported in attendance at an international who workshop on virus neutralisation sponsored by glaxosmithkline. the health protection agency has received funding from chiron vaccines, wyeth vaccines, aventis pasteur, roche, and glaxosmithkline, to carry out analytical work on a contractual basis in mz's laboratory. jmw has no conflicts of interest to declare in relation to this paper. none of these sources of funding had any role in the writing of this seminar. we received no funding in relation to this seminar other than a small payment from the lancet. learning from experience? uses of error reflecting on my medical errors over years of clinical experience, i was disturbed to note that most errors that came to my mind were from the early part of my career. is this a sign that i really did become a better doctor or is it a symptom of ageing? were my early errors more influential on my subsequent practice or are my current errors not recognised or not made known to me by sympathetic colleagues? during my first house job, a middle-aged man was under my care for several months with an infected pleural cavity following a plombage operation for tuberculosis some years previously. he was memorable not only because of his sickness, but also because he was the first patient to give me a present, which i have to this day. months later, i was a casualty officer at a teaching hospital. an intern showed me the chest radiograph of a man with a febrile illness and an opaque hemithorax. i lectured the intern on my patient with the infected plombage, not thinking for a moment that this story was directly relevant to the radiograph i was shown. the patient died of a cardiac arrest in the casualty department. the autopsy showed an infected plombage site and death from untreated septicaemia. years after qualifying, while a locum physician in the northern parts of canada, i was required to do a coroner's post-mortem on a middle-aged man found dead in his cabin. fortunately, the policeman knew what to do and this overcame my anxiety. hours later, i had no doubt that the man was dead, but knew neither why nor how. i dissected the heart and coronary vessels and decided they were atheromatous and that death was from natural causes, probably from myocardial ischaemia. in the coroner's court, i presented my conclusions and the case was closed. i received the pathologist's report as i was due to finish the locum . . . normal heart! being on-call for a unit and not just one's own patients can be an onerous task, particularly as the staff become more numerous and anonymous. in the past years, i have been required to be on-call for a unit of ten consultants at two hospitals, one of which i visit only when on call. i was telephoned in the middle of the night about a patient who had had a cardiac arrest. i did not recognise the patient's name. i was told the arrest team wanted me to advise on their "enthusiasm" for resuscitation. i said that if she was not readily resuscitated, they should not resort to extreme measures, presuming she was a cancer patient admitted under the care of one of my oncology colleagues. on visiting the ward the next morning, i learnt that the patient who had died was a young woman under my care. (i had been given her first name and not her surname). she had been successfully treated for ovarian cancer years previously and had been diagnosed with metastatic disease a couple of weeks earlier. she was neutropenic after the first chemotherapy treatment and a fatal outcome was not anticipated, particularly since she was being treated with curative intent. systematic review and economic decision modeling for the prevention and treatment of influenza a and b textbook of influenza the impact of influenza epidemics on mortality: introducing a severity index differing virulence of h n and h n influenza strains comparison of infection rates and severity of illness for influenza a subtypes h n and h n the tecumseh study of illness: xiii, influenza infection and disease, - the impact of influenza epidemics on hospitalizations impact of influenza and respiratory syncytial virus on mortality in england and wales from mortality associated with influenza and respiratory syncytial virus in the united states population-based study on incidence, risk factors, clinical complications and drug utilization associated with influenza in the united kingdom survey of underlying conditions of persons hospitalized with acute respiratory disease during influenza epidemics in houston burden of influenza illness in children with asthma and other chronic medical conditions influenza and the rates of hospitalization for respiratory disease among infants and young children effect of influenza on hospitalizations, outpatient visits, and courses of antibiotics in children influenzarelated hospitalisations among children in hong kong outbreak of influenza influenza: global surveillance for epidemic and pandemic variants global influenza surveillance: tracking a moving target in a rapidly changing world human influenza a h n virus related to a highly pathogenic avian influenza virus clinical features and rapid viral diagnosis of human disease associated with avian influenza a h n virus surveillance of influenza viruses in guandong province, china in : a preliminary report human infection with influenza h n lack of evidence for humanto-human transmission of avian influenza a h n viruses in hong kong, china molecular characterization of h n influenza viruses: were they the donors of the ''internal'' genes of h n viruses in hong kong? emergence of influenza a h n reassortant viruses during molecular diagnosis of influenza human influenza a (h n ) viruses isolated from china origin and evolutionary characteristics of an antigenic reassortant virus isolated from man in china conjunctivitis in human beings caused by influenza a virus of seals avian influenza virus isolated from a woman with conjunctivitis avian influenza, human-netherlands ( ): fatal case. reported in: promed-mail application of directigen flu-a for the detection of influenza a virus in human and nonhuman specimens comparison of rapid diagnostic techniques for respiratory syncytial and influenza a virus respiratory infections in young children performance of virus isolation and directigen flu a to detect influenza a virus in experimental human infection effect of rapid diagnosis on management of influenza a infections evaluation of directigen flu a and b for rapid diagnosis of influenza type a and b infections evaluation of a new dot blot enzyme immunoassay (directigen flu a+b) for simultaneous and differential detection of influenza a and b virus antigens from respiratory samples evalaution of diagnostic tests for influenza in a pediatric practice evaluation of a neuraminidase detection assay for the rapid detection of influenza a and b virus in children bedside diagnosis of influenzavirus infections in hospitalized children quickvue influenza test for rapid detection of influenza a and b viruses in a pediatric population enhancing public health surveillance for influenza virus by incorporating newly available rapid diagnostic tests clinical signs and symptoms predicting influenza infection influenza b presentation in vaccinated elderly patients: diagnostic considerations. options for the control of influenza iv medical practicebased influenza surveillance: viral prevalence and assessment of morbidity surveillance of respiratory pathogens and influenzalike illnesses in general practices-the netherlands, winter / contribution of influenza and respiratory syncytial virus to community cases of influenza-like illness: an observational study pathogenesis of influenza a and b in humans structure of the hemagglutinin precursor cleavage site, a determinant of influenza pathogenicity and the origin of the labile conformation role of hemagglutinin cleavage for the pathogenicity of influenza virus structural features of the avian influenza virus haemagglutinin that influence virulence initial genetic characterization of the "spanish" influenza virus origin and evolution of the "spanish" influenza virus hemagglutinin gene molecular basis for high virulence of hong kong h n influenza a viruses lethal h n influenza viruses escape host anti-viral cytokine responses induction of proinflammatory cytokines in human macrophages by influenza a (h n ) viruses: a mechanism for the unusual severity of human disease? influenza a virus lacking the ns gene replicates in interferon deficient systems encephalitis and encephalopathy associated with an influenza epidemic in japan influenza-associated encephalopathy in japan randomised placebo-controlled crossover trial on effect of inactivated influenza vaccine on pulmonary function in asthma effects of inactivated influenza virus vaccination on bronchial reactivity symptom scores and peak expiratory flow variability in patients with asthma the safety of inactivated influenza vaccine in adults and children with asthma the guillain-barré syndrome and the and - influenza vaccines live attenuated and inactivated influenza vaccine in school-age children comparison of heterotypic protection against influenza a/taiwan/ (h n ) by attenuated and inactivated vaccines to a/chile/ -like viruses efficacy of inactivated and cold-adapted vaccines against influenza a infection, to : the pediatric experience comparison of us inactivated split virus and russian live attenuated, cold-adapted trivalent influenza vaccines in russian schoolchildren studies of the - inactivated influenza vaccine among children attending day care: immunologic response, protection against infection, and clinical effectiveness a randomized controlled trial of cold-adapted and inactivated vaccines for the prevention of influenza a disease effectiveness of influenza vaccine in health care professionals the efficacy of influenza vaccination in elderly individuals: a randomized double-blind placebo-controlled trial efficacy of influenza vaccine in the elderly in welfare nursing homes: reduction in risks of mortality and morbidity during an influenza a (h n ) epidemic clinical manifestations and incidence of oculo-respiratory syndrome following influenza vaccination-quebec ors during the - influenza vaccination season efficacy of attenuated and inactivated influenza vaccines in school children and their unvaccinated contacts in novgorod, russia influenza vaccination in the prevention of acute otitis media in children influenza a vaccine decreases the incidence of otitis media in to -month-old children in day care does influenza vaccination prevent asthma exacerbations in children? effectiveness of influenza vaccination of day care children in reducing influenza-related morbidity among household contacts the effectiveness of vaccination against influenza in healthy, working adults randomized, placebo-controlled double blind study on the efficacy of influenza immunization on absenteeism of health care workers effectiveness and costbenefit of influenza vaccination of healthy working adults: a randomized controlled trial influenza a among community-dwelling elderly persons in leicestershire during winter - ; cigarette smoking as a risk factor and efficacy of influenza vaccination influenza vaccination programs for elderly persons: cost effectiveness in a health maintenance organization benefits of influenza vaccination for low-, intermediate-, and high-risk senior citizens influenza vaccine effectiveness in preventing hospitalizations and deaths in persons years or older in minnesota clinical effectiveness of influenza vaccination in manitoba effectiveness of influenza vaccine in reducing hospital admissions during the - epidemic influenza vaccine effectiveness in preventing hospitalization for pneumonia in the elderly influenza vaccine effectiveness in preventing hospitalization among the elderly during influenza type a and type b seasons reduction in hospital admission for pneumonia in non-institutionalised elderly people as a result of influenza vaccination: a case-control study in spain effectiveness of influenza vaccination in the elderly in a community in italy influenza vaccination, hospitalisations, and costs among members of a medicare managed care plan study of the effectiveness of influenza vaccination in the elderly in the epidemic of - using a general practice database a meta-analysis of effectiveness of influenza vaccine in persons aged years and over living in the community the efficacy of influenza vaccine in elderly persons: a meta-analysis and review of the literature relation between influenza vaccination and outpatient visits, hospitalization, and mortality in elderly persons with chronic lung disease is immunizing all patients with chronic lung disease in the community against influenza cost-effective? evidence from a general practice based clinical prospective cohort study in utrecht, the netherlands association between influenza vaccination and reduced risk of brain infarction association of influenza vaccination and reduced risk of recurrent myocardial infarction influenza vaccination and the risk of primary cardiac arrest effectiveness of influenza vaccine in reducing hospital admissions in people with diabetes influenza vaccination of health care workers in long-term care hospitals reduces the mortality of elderly patients effects of influenza vaccination of health-care workers on mortality of elderly people in long-term care: a randomised controlled trial influenza vaccination levels and influenza-like illness in long-term-care facilities for elderly people in niigata, japan, during an influenza a (h n ) epidemic a new mf- -adjuvanted influenza vaccine enhances the immune response in the eldeerly with chronic diseases: results from an immunogenicity meta-analysis liposomal influenza vaccine the efficacy of live attenuated, cold-adapted, trivalent, intranasal influenzavirus vaccine in children efficacy of vaccination with live attenuated, cold-adapted, trivalent, intranasal influenza virus vaccine against a variant (a/sydney) not contained in the vaccine amantadine and rimantadine for preventing and treating influenza a in adults (cochrane review) guidance on the use of zanamivir, oseltamivir and amantadine for the treatment and prophylaxis of influenza zanamivir: a review of clinical safety us food and drug administration. relenza pulmonary function and airway responsiveness in mild to moderate asthmatics given repeated inhaled doses of zanamivir efficacy and safety of inhaled zanamivir for the treatment of influenza in patients with asthma or chronic obstructive pulmonary disease: a double-blind, randomised, placebo-controlled, multicentre study comparison of elderly people's technique in using two dry powder inhalers to deliver zanavivir: randomised controlled trial efficacy and safety of the neuraminidase inhibitor zanamivir in the treatment of influenza virus infections randomised trial of efficacy and safety of inhaled zanamivir in treatment of influenza a and b infections clinical efficacy and safety of the orally inhaled neuraminidase inhibitor zanamivir in the treatment of influenza: a randomised, double-blind, placebocontrolled european study inhaled zanamivir for the prevention of influenza in families efficacy and safety of inhaled zanamivir for the treatment of influenza in patients with asthma or chronic obstructive pulmonary disease: a double-blind, randomised, placebo-controlled, multicentre study zanamivir for treatment of symptomatic influenza a and b infection in children five to twelve years of age: a randomized controlled trial randomized, placebo-controlled studies of inhaled zanamivir in the treatment of influenza a and b: pooled efficacy analysis zanamivir for the treatment of influenza a and b infection in high-risk patients: a pooled analysis of randomized controlled trials zanamivir in the prevention of influenza among healthy adults: a randomized controlled trial short-term treatment with zanamivir to prevent influenza: results of a placebocontrolled study use of the selective oral neuraminidase inhibitor oseltamivir to prevent influenza effectiveness of oseltamivir in preventing influenza in household contacts: a randomized controlled trial efficacy and safety of oseltamivir in treatment of acute influenza: a randomised trial efficacy and safety of the oral neuraminidase inhibitor oseltamivir in treating acute influenza oral oseltamivir in treatment of influenza in children long term use of oseltamivir for the prophylaxis of influenza in a vaccinated frail elderly population evidence for zanamivir resistance in an immunocompromised child infected with influenza b virus guidance on the use of oseltamivir and amantadine for the prophylaxis of influenza recombinant influenza a virus vaccines for the pathogenic human a hong kong (h n ) viruses safety and immunogenicity of a recombinant hemagglutinin vaccine for h influenza in humans safety and antigenicity of non-adjuvanted and mf- adjuvanted influenza a/duck/singapore/ (h n ) vaccine: a randomized trial of two potential vaccines against h n influenza pandemic preparedness: lessons learnt from h n and h n candidate vaccines key: cord- -o i hy authors: holliday, ian; tam, wai-keung title: e-health in the east asian tigers date: - - journal: int j med inform doi: . /j.ijmedinf. . . sha: doc_id: cord_uid: o i hy objective: the article analyzes e-health progress in east asia's leading tiger economies: japan, hong kong, singapore, south korea and taiwan. it describes five main dimensions of e-health provision in the tigers: policymaking, regulation, provision, funding and physician-patient relations. methods: we conducted a series of fieldwork interviews and analyzed key healthcare websites. results and conclusion: our main finding is that the development of e-health in the region is less advanced than might be expected. our explanation focuses on institutional, cultural and financial factors. the application of information technology (it) to public sector operations sometimes captured in the notion of e-government is starting to have an impact on developed healthcare systems the world over. as time goes by, that impact is expected to become even more pronounced. ''the consensus seems to be that new information technologies will significantly affect almost every aspect of health care,'' wrote blumenthal [ ] . in this article, we examine the progress of e-health in the five leading economies of east asia: japan, hong kong, singapore, south korea and taiwan. each seeks to place itself at the forefront of the information revolution and has high levels of internet access and usage. each also has a sophisticated healthcare system dedicated to securing maximum healthcare benefit at minimal cost. by standard outcome indicators, these systems all have very good records. the tigers, therefore, form a cluster in which e-health might be expected to be notably advanced. however, our finding is that although some progress is being made, it remains limited. it is also variable across the five societies. the article begins by reviewing some of the literature on e-health taking from it a series of critical dimensions and issues. it then briefly analyzes the two relevant contextual aspects of the east asian tigers: their participation in the information age and the nature of their healthcare systems. on these bases, it examines their e-health progress, focusing on the major themes unearthed in the contemporary literature. finding limitations and variations, it concludes by thinking through possible explanatory factors, focusing on institutional, cultural and financial issues. much of the existing e-health literature has been developed in the context of the united states, reflecting both us leadership in the information age and the continuing search for solutions to us healthcare problems. five main themes are prominent. four of the five address distinct dimensions of the broad policy and management framework for healthcare, examining internet impacts on policymaking, regulation, provision and funding. the fifth theme looks inside the healthcare sector and inside the surgery, at the implications of the internet for physician-patient relations. eventually, this may have policy significance, but for now, it is best treated separately. the major argument made about healthcare policymaking is that the us government has been slow to engage with the numerous issues generated by the it revolution [ ] . the core features of that revolution, notably enhanced information flows, increased networking possibilities and novel commercial opportunities, are now well documented [ ] . however, it is said that in us healthcare, most policy actors in both congress and the executive branch continue to focus on pre-information age agendas. although, the bush administration has started to address these concerns, the result remains something of a lack of internet-related policy activity and only a limited number of perspectives on the internet's potential to transform the us healthcare system. clearly structural features of the us system, including fragmentation both of government and of the healthcare sector, play key roles. looking at the narrower sphere of regulation, concerns are expressed about the failure of regulatory agencies to keep pace with internet-related developments. goldsmith notes that the internet generates many potential regulatory problems, ranging from licensing e-health practitioners to monitoring information quality in a virtual world with no boundaries [ ] . fried et al. detail some of the obstacles placed in the way of e-health by existing regulations, holding that individuals and organizations must navigate a maze of rules and codes, old and new, if they wish to implement fresh ideas and approaches [ ] . kassirer's prediction is that the courts will play a role when substandard medical advice provided through web sites or e-mail yields poor medical outcomes. he believes that courts will be especially important when professional advice is given without a direct patient encounter, or when state lines are crossed [ ] . some regulatory issues are us-specific, but many have much wider relevance. partly building on the regulatory theme, analysts have also debated the limitations currently imposed on healthcare provision through the internet. kleinke argues that the internet will not contribute to a solution to the administrative redundancies, economic inefficiencies, and quality problems that have long plagued the us healthcare system. instead, it will exacerbate the cost and utilization problems of a system in which patients demand more, physicians are legally and economically motivated to supply more, and public and private purchasers are expected to pay the bills [ ] . goldsmith holds that the challenges of standardizing coding and formats for clinical information, and protecting patient privacy, will hinder the realization of network computing potentials in healthcare [ ] . the problems to which these and other authors point are structural. economic, organizational, legal, regulatory, and cultural conflicts rooted in the us healthcare system are all barriers to e-healthcare provision. further problems are found in the sphere of healthcare funding. shortliffe criticizes congress for focusing on short-term benefits, arguing that research investment for e-health must be balanced between basic and applied analyses [ ] . robinson examines the effect of distinct forms of capital on the development of the healthcare internet. in the late s, venture capital flooded into the ehealth sector, rising dramatically from us$ million in early to us$ million in late . in the same period, e-health firms went public, raising us$ . billion at their initial public offerings. however, the technology-sector crash in late hit the e-health sector especially hard, prompting an extended period of consolidation between e-health and more conventional firms [ ] . us funding problems thus relate to both the public and the private sectors. finally, analysts have looked inside the surgery at physician-patient relations. existing survey data show that citizens make considerable use of the internet for healthcare information and services, mostly of a generic kind [ ] . indeed, anderson reports that in , % of us adults with internet access did so [ ] . as more patients go online, increasing numbers will turn up in surgeries with internet-fueled questions and concerns. meeting the growing expectations of these individuals will be a significant challenge for physicians [ ] . assessing the likely impact, kassirer argues that the internet will change the physician-patient relationship in unpredictable ways, with some aspects of electronic communication strengthening the bond, and others undermining it [ ] . goldsmith believes patients have most to gain from the emergence of the internet, arguing that it will rebalance the steeply asymmetrical medical knowledge held by patients and physicians [ ] . using information gained through internet searches, patients can now open their dialogues with physicians at a much higher level than before, and thereby gain leverage in the care process. ball and lillis also discuss the potential challenges the internet presents to physicians. as internet searches often generate as many questions as answers, physicians are likely to find themselves under increased workload pressures [ ] . the variable quality of healthcare information accessed through online searches [ ] , a matter that is being actively addressed by bodies such as the health on the net foundation (www.hon.ch) and the internet healthcare coalition [ ] , can only reinforce those pressures. zupko and toth hold that physicians sometimes encounter a form of cultural shock when confronted by well-informed patients [ ] . it is therefore perhaps not surprising that an april survey found that physicians are much more reluctant than patients to use the internet for healthcare interactions. while % of patients wanted to exchange e-mail with their doctors, only about % of doctors actually did so. physician-patient confidentiality, time concerns and increased exposure to malpractice liability were cited as primary reasons for doctors' wariness [ ] . in the face of this mounting speculation and evidence, lumpkin is sanguine, however, contending that the physician-patient encounter is little changed, despite widespread internet usage in healthcare [ ] . though focused on the us, the existing e-health literature generates key themes for an analysis of progress in other parts of the world, including the east asian tigers. however, before exploring those themes, we first present some basic contextual information about our five societies. two features of the east asian tigers are particularly relevant to this analysis: their participation in the information age and the nature of the healthcare systems in which their application of it needs to be assessed. in this section, we examine both features. looking at broad social participation, it was exploited more rapidly in the five east asian tigers than in any other global cluster. for many years, the nielsen//netratings global internet index has ranked all five societies in the top worldwide for personal computer (pc) connections and internet access and usage. the four smaller societies, hong kong, singapore, south korea and taiwan, are particularly advanced. furthermore, the severe acute respiratory syndrome (sars) crisis that hit the region in spring gave a major boost both to internet usage in general, and to e-health in particular [ ] . in hong kong, for instance, the number of active internet users increased by % from february to april , before falling back by % from april to june . the overall increase was %. also at the start of , the time spent online by hong kong people first increased by % and then fell back by %, registering an overall increase of % [ ] . consistent with the image of economic and social dynamism, they have projected for many years now, the east asian tigers are among the most advanced it societies on earth. to some extent, this strong it orientation is the product of developmental state strategies. with the partial exception of hong kong, the east asian tigers have long placed considerable faith in stateled growth strategies. furthermore, for many years they have frequently focused those strategies on it and it-related sectors. in japan, in the s, the fabled ministry of international trade and industry targeted supercomputers and the fifth generation as a major development project [ ] . despite a long period of economic stagnation in the s, the japanese it industry remains a significant global force. in singapore in the s, the state took the lead in nurturing wafer fabrication, the most sophisticated ''front end'' of the semiconductor industry. chartered semiconductor manufacturing, established by the government in , is now the third largest silicon foundry in the world. in south korea, in the early s, the state reorganized the public-sector telecommunications system by closing inefficient firms and allocating profitable segments to major chaebol like samsung and goldstar, enabling them to establish specialized chip businesses. by the early s, samsung had become the world's number one producer of dynamic random access memories for pcs and workstations. in taiwan since the s, the ministry of economic affairs and the state-controlled electronics research service organization have played crucial roles in developing the semiconductor industry. today, it is the fourth largest in the world, and firms within it have entered into strategic alliances with leading industry players in the west [ ] . even in hong kong, where a developmental state took longer to emerge, the government is currently overseeing the construction of a flagship cyberport, intended to host a strategic cluster of companies and professional talents, specializing in it applications, information services and multimedia content creation, and designed to project a hi-tech international digital city image. the east asian tigers are also leading players in the development of e-government. the un/aspa benchmarking survey of all un member states placed singapore at number (a long way behind the us, but only fractionally behind australia and new zealand), south korea at number and japan at number . all three states featured in the top category of high e-government capacity. the survey did not assess hong kong and taiwan, neither of which is a un member state. the report noted that singapore ''demonstrated a balanced and citizen-centric e-government program, while possessing the benefits of a high technological infrastructure and human capital measures''. it held that south korea ''made perhaps the most dramatic advances in its e-government program by successfully implementing several new online transaction features''. it was more critical of japan, arguing that it had ''yet to live up to its rather significant potential''. ''japan's e-government program has not yet reached a comparable level of sophistication as that of the regional leaders due primarily to achieving only a limited interactive presence among national government websites'' [ ] . a january analysis of e-government in east and southeast asia reached similar conclusions, identifying the five tigers as regional leaders [ ] . accenture's survey looked at only two of the five east asian jurisdictions analyzed here. it ranked singapore number in the world after canada, and japan number [ ] . looked at from many different perspectives, then, the east asian tigers are leading participants in the emergent information age. healthcare systems in the tigers share a basic orientation, but are otherwise quite varied. the orientation is best termed productivist, in that in each society social policy has usually been subordinate to economic objectives. while the governments of all five tigers certainly get involved in social policy, they usually do so either for economic reasons or after they have made provision for their various economic goals. the main stimuli to this strong focus on economic development were, in all cases, the devastation brought by the second world war, and the uncertainties of the international order constructed thereafter [ ] . this shared orientation has fed into healthcare policy in three main ways [ ] . in japan and its two former colonies, south korea and taiwan, healthcare was initially left chiefly to the market. only once economic policy was on track and a measure of growth had already been attained, did these societies turn their attention to planning their healthcare systems. in doing so, they concerned themselves chiefly with healthcare finance, creating social insurance systems by gradualist means. now, in all of these societies, the health insurance scheme is universal in aspiration and near universal in fact. across all three societies, healthcare provision remains privatesector-driven, with the state performing a chiefly regulatory role. traditional medicines are significant in all three societies and covered by national health insurance schemes [ ] . however, they are not consistently brought within the planning frame. in hong kong, until the early s, the colonial government took a strictly reactive and incremental approach to healthcare. its major interventions focused on subventing charitable organizations in the healthcare business, though in time, it also built hospitals and delivered care directly through them. throughout, government activity was funded out of general government revenue. the major and to date, only step change came in , with the formation of the hong kong hospital authority (hkha). this imposed state control and state funding on the secondary sector and gave hong kong a miniature version of the british national health service. however, there has never been any attempt to bring primary care within the planned healthcare system. only in , was traditional chinese medicine subjected to anything more than minimal government regulation [ ] . in singapore, the early post-war experience was similar to that of hong kong. here, however, separate initiatives were taken in the spheres of provision and funding. in , much provision was integrated at the secondary care level through creation of the state-run hospital corporation of singapore. this body subsequently sought to drive private-sector disciplines into state provision through ''corporatization''. in , in an attempt to generate integrated pathways of care, it was broken into two territorial clusters focused on the secondary sector but also having primary and tertiary elements. however, as most of the primary sector remained outside the state sector, the extent of integration was limited; in singapore, the state provides % of secondary care but only % of primary care. on the funding side, singapore in created a compulsory savings system, medisave, within the wider central provident fund scheme. it added the insurance schemes medishield and medishield plus in and and created a basic social safety net, medifund, in . these various schemes partially fund secondary care provision. there is also some direct state subsidy. funding of primary care takes place mainly through out-of-pocket expenses. the traditional sector stands outside all state planning and, as in hong kong, has only recently been brought within the regulatory framework. these healthcare systems have enviable records. not only did they make a rapid post-war transition from the contagious disease characteristic of thirdworld countries to the chronic disease characteristic of first-world societies, but also they register very favorable health outcomes as measured by standard input and outcome indicators (table ) . healthcare systems in the east asian tigers thus share a productivist orientation and strong performance. they exhibit varied state roles, with much healthcare activity lying outside the public sector and some of it falling beyond the planning horizon. in japan, south korea and taiwan, state involvement is extensive in finance but limited in provision. in hong kong, the government both funds and directly provides care in the secondary sector, but not elsewhere. in singapore, the state provides a large amount of secondary and some primary care. the funding regime is complex, comprising direct state subsidy, forced individual saving, state-run and private-sector insurance, and out-of-pocket expense. in all five tigers, both the public and private sectors play important roles and face clear incentives to take an interest in harnessing the internet for healthcare gain. note: taiwan data are from . sources: [ ] . against the dual backdrop of sophisticated it societies that make extensive use of the internet and cost-effective healthcare systems driven in variable ways by actors from the public and private sectors, we now turn to a survey of e-health in the east asian tigers. to frame the survey, we begin by providing a brief descriptive overview of the major state-run healthcare websites in the region. we then structure our analysis using the five main analytical spheres that dominate the existing e-health literature: policymaking, regulation, provision, funding and physician-patient relations. all ministries or departments of health in the east asian tigers have their own website. throughout the region, the major quasi-autonomous state agencies, such as the national health insurance agencies in japan, south korea and taiwan, the hkha in hong kong and the two big healthcare clusters in singapore, also have sites. here, we look only at the main government healthcare sites ( table ) . the overall quality is high. all have clickable links to organizational objectives and tasks. most also offer detailed information about subsidiary divisions. all contain links to the government homepage and related healthcare sites so that visitors can conduct further searches and collect additional information. all provide feedback channels. in singapore, the ministry of health (moh) offers online feedback opportunities. in taiwan, citizens can make online appointments with the director of the department of health (doh). in japan, the ministry of health, labour and welfare (mhlw) uses e-mail to solicit however, within this generally strong showing, there are also significant differences, with japan's mhlw and to a lesser extent, hong kong's hwfb lagging behind their regional counterparts in key respects. firstly, the mhlw fails to provide contact details for named officials on its website. this is standard practice in the other four tigers. singapore's moh, for example, gives address, telephone number and e-mail details for key officials. secondly, while healthcare professionals and officials in singapore, south korea and taiwan can communicate with each other through the internet, their counterparts in japan and hong kong cannot. thirdly, the range of options available to users is more restricted in japan and hong kong than in the other three tigers. in south korea, for instance, it has played a role in the surveillance system for communicable disease since . through electronic data interchange and regional database management systems, notifying and reporting systems have been computerized, and an electronic record of all notified and reported cases is kept. using the super-highway communication network, physicians and public health centers can access the notifying and reporting system, disweb, anywhere and anytime through the internet (http://dis.mohw.go.kr). in singapore, the moh site within the government's ecitizen portal enables healthcare professionals to download application forms for license renewal, approval to perform a pregnancy termination, and so on. the policymaking strand of the e-health literature castigates us policymakers for being slow to grasp the potential of the internet. such a charge is less easy to sustain in the east asian tigers, though again experience is variable. singapore and taiwan are the regional leaders. singapore's ecitizen portal addresses many aspects of citizen interaction with government, with healthcare being a prominent theme. the internet is used to reinforce the public health messages that have been disseminated by the singaporean government through other media for many years. behind the scenes, e-mail links pervade the healthcare system and enhance the cohesiveness of policy networks. in a controlled city state, those networks are in any case very tight. in taiwan, the doh in launched an ambitious e-health project, with a timeline stretching to . the health information network that is central to this initiative has a backbone funded by central government and permits local users in both the public and private sectors to participate on a self-paying basis. drawing on us experience, it seeks to promote electronic medical records, based on a smart card system, so that information can flow to all parts of the healthcare sector. a healthcare certification authority, created in , oversees promotion of this initiative. in the other three tigers, progress is less impressive. japan launched an e-japan strategy in january , designed to make it ''the world's most advanced it nation within years'' [ ] . the strategy had an explicit e-government strand. in september , the mhlw followed up by issuing a ''grand design'' for promotion of it in the healthcare sector. the aim was to computerize the entire sector by and to introduce an electronic medical record system covering % of clinics and % of hospitals with plus beds by . progress towards targets appears to be on track. however, japanese performance in the e-health domain is poor by regional standards. hong kong is also quite slow to place healthcare online. the hwfb site contains standard bureaucratic information, such as current policy initiatives and recent speeches, plus public health information that has been developed particularly since the sars crisis. here, the major networking initiative is being taken by the dominant public-sector delivery agency, the hkha. while its primary focus is provision, the networking links being created among hospitals are likely to have policy consequences. as in singapore, e-mail links also bolster ties within policy networks that are already quite cohesive. south korea is making an aggressive attempt to exploit the internet across all areas of government, but in the healthcare sphere, currently remains an average performer. turning to regulation, three main issues are raised in the literature. the first is that e-health generates a number of regulatory problems. the second is that excessive regulation may impede e-health progress. the third is that the courts are likely to have to step in when administrative regulation fails. in the east asian tigers, regulation is clearly a major concern and an evident constraint on ehealth development, often for good reason. one instance is limitations placed on consultations, which in all five tigers quite properly mandate face-toface physician-patient contact before any specific healthcare information or advice can be given. for the foreseeable future, online consultation, though technically feasible, is likely to be restricted by professional concerns. another instance is limitations placed on information sharing and exchange, which in all the tigers are again very properly re- stricted by privacy considerations. however, there is some variation in regional regulatory practice. in singapore, patients requiring repeat prescriptions can place an order online and have the medications delivered to their homes. only after months, do they have to return to the healthcare system to consult a physician. elsewhere, this practice is illegal. in japan, physicians are prohibited from answering specific questions about healthcare or disease by e-mail or telephone. regarding provision, assessments in the us literature are mainly negative. on the one hand, the argument is made that it cannot be expected to solve structural problems in healthcare systems. on the other, barriers even to less ambitious networking initiatives are held to be substantial. these are fair points, but they should not be allowed to obscure the real progress being made by healthcare systems around the world, and in our case in east asia. among the five tigers, taiwan's healthcare websites, both public and private, provide the most comprehensive services to patients. singapore ranks second, and hong kong third. japan and south korea are somewhat behind the regional pace. an overview is given in table . in taiwan, the doh operates a taiwan e-hospital site to provide free online medical advice to patients (http://taiwanedoctor.doh.gov.tw/). currently, medical practitioners and nutritionists from public hospitals form a consulting team to answer questions about specialties. patients seeking general medical advice can send questions to a particular practitioner and receive feedback online or by e-mail. in the private sector, a number of hospitals, such as the chang gung memorial hospital, have online question-and-answer services for patients. the kingnet second opinion webhospital (www.webhospital.org.tw) and the taiwan physician's net (www.doctor.com.tw) are two prominent sites providing free online medical advice to patients. established by kingnet entertainment (www.kingnet.com.tw) in , the webhospital has some voluntary physicians answering questions from the public. the taiwan physician's net brings together about physicians, whose information and advice are posted on the web. apart from getting online medical advice, patients can search for a particular physician and visit his or her office for treatment. in taiwan, patients can also make medical appointments online with many public and private hospitals. looking to the future, the doh is planning to develop a medical information exchange center to promote information sharing and enhance treatment quality. in singapore, health is one of a number of cluster points within the ecitizen site. to date, the internet is mainly used to provide general healthcare information, with the healthcare portal containing comprehensive information about healthcare providers, the healthcare establishment, healthy lifestyles and public health issues such as sars. many searches are possible. the site also allows individuals to submit complaints and feedback. only a few transactions can be undertaken online. as in taiwan, appointments can be made and altered online. through singapore's e-pharmacy services, recurrent prescription items can be ordered online and delivered throughout the island. in one of its two main healthcare clusters, patients can register online and access summary medical records. inside the healthcare system, information flows are starting to change as polyclinics and gps gain access to hospital records online. the likelihood is that enhanced integration of the public and private sectors will result. in hong kong, the hkha, which oversees almost the entire secondary sector, is currently introducing online networking in hospitals. its clinical management system is an integrated clinical workstation giving clinicians access to departmental information and patient records. it will soon develop into a longitudinal electronic patient record within the public hospital system, enabling records to be accessed by many parties simultaneously anywhere, anytime. the system will also actively support clinical decisions by offering alerts, reminders, links to medical knowledge and other aids. it is expected to play an important role in reducing medical errors and improving the quality of patient care. over the next years, the hkha is planning to create a hong kong health information infrastructure, with the aim of networking all healthcare providers in the public, private and social welfare sectors. it also intends to build an electronic medical record for every hong kong resident and provide citizens with an electronic gateway to healthcare information and evidence-based medicine [ ] . these initia-tives are likely to enhance information flows within the public healthcare system. compared with taiwan and singapore, however, hong kong lags behind in developing internet services for patients. individuals cannot register and access summary medical records online. lacking an e-pharmacy service, the hong kong system does not allow recurrent prescription items to be ordered online. japan and south korea are falling behind their regional counterparts in providing online health services to patients. their official health websites do not deliver any electronic service to individual patients. with the exception of initiatives taken by a small number of private hospitals in south korea, like the yonsei eye and ent hospital, neither public nor private hospitals in these two tigers allow patients to register online. however, in , japan's mhlw established telemedicine networks to provide specialized care to people in remote areas. the government will provide us$ million a year to form networks consisting of one large hospital and three clinics working together to supervise patients. each patient will be equipped at home with a computer that can monitor heart rate, blood pressure and other indicators, as well as a phone capable of transmitting video. they will be linked to physicians through an isdn digital phone connection, thus enabling physicians to diagnose illness by electronically transmitted data. from june , the mhlw started to establish such networks a year, so that all districts will have at least one by [ ] . in , south korea's semipublic seoul national university hospital founded ezhospital, which is business-oriented instead of patient-oriented. with three main business elements, education (content services), e-trading and system integration, ezhospital is starting to alter purchasing arrangements for both medical and non-medical supplies. as the south korean system is highly fragmented, the purchasing consortia that can be built through the internet could one day become significant. at present, however, e-purchasing is at an early stage of development. analyses of e-health funding focus on one main issue, the short-termism of us initiatives. in this domain, it is difficult to reach an overall assessment of the tigers' performance. on the one hand, their developmental state orientations make the general climate for it industrial emergence very different from the climate found in the us. in this regard, the tigers look to the long term in a systematic fashion that has no us equivalent. on the other hand, it is hard to find evidence that the tigers are investing heavily in e-health applications. moreover, because the private sector plays such a large regional role in healthcare, as it does in the us, many of the relevant initiatives fall outside the state sector and are hard to capture. there are undoubtedly many small commercial initiatives in east asia as, again, there are in the us. furthermore, like other commercial websites, private healthcare sites throughout the region rely heavily on advertising and sale of products for income. to take just two taiwanese instances, the kingnet webhospital and the taiwan physician's net offer online sales not only of healthrelated products, but also of cinema tickets. the very fragmented nature of private-sector healthcare operations throughout the tigers means that few summary assessments can be made. looking finally at physician-patient relations, the existing literature contains variable forecasts of unpredictable change, little change, and so on. however, there is a clear belief that patients have most to gain from e-health and physicians correspondingly have most to lose. in general, physicians in the tigers have tended to be wary of exploiting the internet for patient interactions. this partly reflects the tight regulatory climate in which many find themselves, with many modes of physician-patient contact outlawed. it may also reflect a certain reluctance on the part of both physicians and patients to engage in the informalities of online contact. until recently, then, the emergence of virtual physician-patient relations was highly limited. since the spring sars crisis, however, the pattern may have started to change. although it is too early to register the longterm impact of the crisis, it is clear that during the sars outbreak, many individuals sought to shift to online interactions with healthcare professionals. the fear of visiting surgeries and, in particular, hospitals that gripped the region in has certainly not disappeared and seems likely to provide a lasting stimulus to virtual delivery of healthcare. furthermore, the generic healthcare information found in great abundance on english-language websites is paralleled on regional websites operating in chinese, japanese and korean. there is also some official encouragement for patients to migrate to e-health. in may , hong-jen chang, ceo and president of taiwan's bureau of national health insurance, argued at an oecd forum that e-health could make a major contribution in informing patients. as evidence, he cited taiwanese experience in confronting hiv/aids and the role of the internet in educating patients about the disease. in the long run, he contended, patients equipped with information gained from online searches ''will translate into quality improvement and efficiency gains for the system'' [ ] . overall, east asian societies retain many traditional features, which generate some resistance to change in established modes of physician-patient contact. nevertheless, there are also factors operating in the opposite direction. one long-term impact of the sars crisis seems likely to be heightened caution about visiting healthcare facilities, for fear of contracting infectious disease, and a consequent boost for e-health. the east asian tigers form the most wired cluster of societies found anywhere in the world. moreover, they have long had a developmentalist orientation that has seen their states become involved in many aspects of economic and social development. in the sphere of e-health, however, their performance is strong at the level of basic web provision, but otherwise not particularly advanced. on the whole, their health ministries or departments have good sites covering all the fundamentals of online provision. outside central government agencies, they often have a wealth of additional sites in the public and private sectors. beyond that, they do not make pioneering use of the internet in healthcare. there are many possible reasons for this slightly disappointing performance, some of which apply to all of the tigers and others which are specific to a particular society. in japan, the structural problems that mired the economy in stagnation for more than a decade from the early s also form part of the explanation for its sluggish e-health performance. a notable feature of the japanese healthcare system is the considerable power of the japan medical association and its extensive links to the liberal democratic party that has governed the country for almost all of the post-war period. in hong kong, the sovereignty transfer was quite disruptive, and only several years on is the political system taking a settled shape on the developmental state model. looking beyond the specific circumstances of individual tigers, however, the major explanatory factors appear to be institutional, cultural and financial. institutionally, east asian healthcare systems tend to be highly fragmented, notably in japan, south korea and taiwan. in consequence, policymakers in healthcare ministries and departments have rather few levers that they can use to direct change. in the e-health sphere, they can quite easily construct official government websites, but generating reform in the wider healthcare system is more difficult and depends on their success in building consortia of interest among many private-sector actors. in part, they seek to do this by offering ring-fenced seed money for specified development projects. in part, they resort to exhortation, calling on all members of society to engage in the project of securing and maintaining regional and/or global leadership in the information age. in these many respects, the east asian tigers have a great deal in common with the us. in the additional domain of culture, they differ from the us. while capitalism is certainly a dynamic force in east asia as in north america, it also co-exists with still vibrant cultural underpinnings. the confucian heritage that characterizes all five east asian tigers has many complex strands. among them is considerable respect for authority, hierarchy, status and so on. in the medical sphere, one consequence is that doctors tend still to be accorded considerable professional status. this may make it difficult for full commercialization to take place and for the market drive that characterizes ehealth in the us to work its way through the system. finally, the financial dimensions of healthcare in the east asian tigers should not be overlooked. these are healthcare systems that deliver the excellent outcomes already mentioned at a fraction of the cost registered in the us and, indeed, in most developed societies. as a proportion of gdp, east asian tigers spend between and % on healthcare, with most coming in at around %. this is far below the us figure of - %, and also below the highincome country standard of almost %. one result of the tigers' success in holding down healthcare costs is that the incentive to experiment with new initiatives is reduced. clearly, there still are some incentives, but they are not as strong as in the us. e-health in the east asian tigers remains at an early stage of development. all have attained a good basic standard, but few are engaged in pathbreaking initiatives. alongside institutional factors that are similar to those found in the us, cultural and financial factors help to explain this rather unsatisfactory level of performance. doctors in a wired world: can professionalism survive connectivity? milbank q the internet promise, the policy reality the information age: economy, society and culture. vol. ii. the power of identity the information age: economy, society and culture. vol. i. the rise of the network society the information age: economy, society and culture. vol. iii. end of millennium how will the internet change our health system? ehealth: technologic revolution meets regulatory constraint patients, physicians and the internet com: the failed promise of the healthcare internet networking health: learning from others, taking the lead financing the healthcare internet rethinking communication in the e-health era consumers of e-health: patterns of use and barriers the impact of cyberhealthcare on the physician-patient relationship e-health: transforming the physician/patient relationship health care web sites: are they reliable? internet healthcare coalition, e-health quality partners named exclusive education and outreach affiliate of the internet healthcare coalition physicians get on line, aspen publishers doctor-patient e-mail slow to develop, international herald tribune nielsen//netratings, internet provided vital information and alternative access to shopping, banking and education for people in hong kong as sars took hold online shopping and banking sites soared in popularity as people in hong kong shunned the crowds sars stimulates ongoing growth in internet usage in hong kong divided sun: miti and the breakdown of japanese high-tech industrial policy tiger technology: the creation of a semiconductor industry in east asia united nations/american society for public administration building e-government in east and southeast asia: regional rhetoric and national inaction high performance, maximum value productivist welfare capitalism: social policy in east asia welfare capitalism in east asia: social policy in the tiger economies traditional medicines in modern societies: an exploration of integrationist options through east asian experience agenda-setting for the regulation of traditional chinese medicine in hong kong networking health: dawning of the e-health era. paper presented to apami-mic conference at the hong kong convention and exhibition centre e-health and the informed patient, paper presented to oecd forum taiwan council of economic planning and development, taiwan statistical data book world development indicators the work described in this article was substantially supported by a grant from the research grants council of the hong kong special administrative region, china [project no. cityu / h]. initial seed funding was provided by the governance in asia research centre, city university of hong kong.we are grateful for the research support we received. we thank academics, officials and practitioners in east asia for talking to us about e-health. the usual disclaimer applies. key: cord- -bhzctz authors: ngan, olivia miu yung; sim, joong hiong title: evolution of bioethics education in the medical programme: a tale of two medical schools date: - - journal: international journal of ethics education doi: . /s - - - sha: doc_id: cord_uid: bhzctz bioethics education in the anglo-european context developed since and was incorporated into the undergraduate and postgraduate education, residency training, and continuous education. in the asia-pacific region, bioethics education is less structured and often dependent on contextual constraints. this paper provides a cross-sectional analysis, describing institutional experiences in developing bioethics curriculum at two medical schools in malaysia and hong kong. the medical programmes of the two institutions are distinctive in terms curriculum framework, teaching approach, and topic selection, and common challenges include implementation of bioethics courses, students’ resistance to bioethics, and limited teaching capacity, emerged as they evolve. the reported experiences revealed that there is room for improvement regarding how medical schools integrate bioethics education in regions where curriculum development remains at an early stage. at least, a bioethics education requires both top-down support from the faculty to improve teaching and educational quality, as well as from the bottom-up approach to empower students to raise awareness and concerns toward bioethics, and helps students developing reasoning through challenging issues. moral conduct in the clinical practice demonstrated through attitudes and behaviours is a transcendental element in medical education. entering medical school as students and later becoming clinicians involves a transformative process emphasising knowledge competencies, codes of practice compliance, and moral development (holden et al. ) . clinical knowledge acquisition has been the core in the medical education and establishment of virtues values through bioethics training have been underexplored in medical education. bioethics in the anglo-european context has developed since and has been incorporated into the undergraduate and postgraduate medical curriculum, residency training, and continuous professional education. in the asia-pacific region, bioethics education did not gain attention until the s, and teaching deliveries remained inconsistent and less structured depending on contextual factors (miyasaka et al. ). one of the common barriers in the implementation of a curriculum in a resource-constrained context is a lack of teaching capacity (ten have ) . teaching bioethics requires expertise both in ethics and medicine. nonetheless, many teachers who are involved in bioethics curriculum in medical programmes were either philosophers, ethicists, or scientists with limited experience in medicine, or clinicians with inadequate formal training in ethics (ekmekci ; sim et al. ) . universities have a limited capacity to provide professional training of ethics and moral philosophy to sustain teaching quality. another common challenge is limited curriculum time to include ethics in the packed medical teaching timetable (ravindran ) . successful curriculum development implementation requires continuous and multifaceted consideration. there is a four-stage framework describing the action plan for progressive changes in the curriculum development, specific to bioethics curriculum in medical education over time, in terms of the implementation, content, teaching capacity, and instruction method (sherer et al. ) . in stage , there is no bioethics course in the institution. in stage , bioethics is taught from a philosophy course with a limited clinical perspective, emphasising on theories and knowledge acquisition. the capacity in supporting teaching is little and didactic lecture is the primary teaching delivery. in stage , bioethics is taught as an independent course, covering ethical issues arise from clinical practice, communication skills, and empathy. in addition to didactic teaching, other teaching methods, including small-group discussion and research project, are adopted to encourage intellectual exchange. in stage , the bioethics curriculum is taught by a multidisciplinary faculty team, including physicians, philosophers, and attorneys. the framework is a good indicator, particularly for developing countries, in determining the current status of bioethics education at medical schools. bioethics is taught in almost all medical schools in malaysia (sim et al. ) and hong kong (becker ) , and the teaching framework and deliveries vary to a great extent depending on the contextual factors. this paper provides a narration describing institutional experiences in developing bioethics curriculum at two medical schools the university of malaya and the chinese university of hong kong. malaya gained independence from british colonial rule in . in , malaysia, comprising the peninsula (west) and sabah and sarawak (east) was formed. the country is run based on parliamentary democracy. the legal system incorporates civil law, derived from british elements, and aspects of syariah laws for muslims. malaysia, with a population of . million, is a prime example of a plural society. the largest ethnic groups in malaysia are the malays ( %), chinese ( %), indians ( %), and others ( %) (department of information ). in sabah and sarawak, there is a myriad of indigenous ethnic groups with their own unique culture and heritage. due to the multi-racial characteristic of the population, it also has varieties of culture, religion, social norms and values. all these cultures have influenced each other, creating a genuinely diversified malaysian culture. the malaysian medical council (mmc) operates under the medical act of and regulates the registration and practice of medical practitioners (malaysian medical council ). over the years the mmc has undertaken the role of granting recognition to other medical schools in the country and overseas and added the name of these schools to the existing register of recognised medical degrees in the second schedule of the act. it is recommended that the mmc establishes an active functional 'education committee' and that the role of mmc in medical education should be clearly and explicitly stated in the act. currently, there are malaysian medical schools, including public and private institutions (wong & kadir ) . the university of malaya (um) is the oldest public tertiary institution in malaysia, providing a five-year undergraduate medical programme -bachelor of medicine and bachelor of surgery (mbbs). at present, um adopts a system-based and problembased approach that integrates the teaching around the major body system, covering both basic scientific foundations and clinical reasoning skills development. before the medical curriculum reform took place in , the teaching and assessment focused on the acquisition of medical knowledge and clinical skills, and the humane aspect of medicine was largely neglected. the course content is divided into three main components that run vertically through the course, namely: (i) the scientific basis of medicine, (ii) the doctor, patient, health and society, and (iii) personal and professional development. the scientific basis of medicine component includes the study of the normal human body and its function (anatomy, biochemistry, physiology); the body's reaction to injury (medical microbiology, pathology, parasitology pharmacology) and practice-based clinical medicine (anaesthesiology, biomedical imaging, emergency medicine, internal medicine, obstetrics and gynaecology, orthopaedic surgery, opthalmology, otorhinolaryngology, paediatrics, primary care medicine, psychological medicine, social and preventive medicine surgery). the doctor, patient, health and society (dphss) module includes the study of preventive, promotive, environmental and occupational health in the community; medical statistics, epidemiology, two field projects (community residency program, crp; organisation and management of health services, omhs); community family case studies, cfcs and family health. the personal and professional development (ppd) module includes improvement of learning, analytical, critical thinking and communication skills, nursing skills, medical ethics, research methodology and exposure to optional fields of interest via elective programs. under the past curriculum, bioethics was appended under personal, and professional development theme and lecture was the primary mode of delivery. there was no formal assessment on the subject. bioethics was not a popular subject among medical students. this was reflected by poor attendance, in particular, among pre-clinical students. some faculty members also do not consider bioethics a 'real' topic to be taught. at that time, the development of bioethics education was slow and insignificant. starting from , the medical education and research development unit (merdu) has been actively involved in the curriculum reform and is now responsible for overseeing the bioethics curriculum. the current medical programme comprises of four themes, namely basic and clinical sciences, patient and doctor, population medicine, and personal and professional development. compared with the past curriculum, the most significant change in the revised curriculum is that personal and personal development module has been upgraded to a theme. while only ethics and professionalism were emphasised previously, bioethics, professionalism, humanities, and health law are given emphasis in the revised curriculum. this is to ensure that students not only grow professionally into good doctors but also receive a holistic experience in humanities other than science teaching in the medical curriculum. a unique feature is the 'language in medicine' component, which provides an early introduction to the humanities in medicine (sim et al. ) . students learn about icons in medicine, historical events in medicine, death and dying, end-oflife issues, and organ transplantation. (figure ). today, bioethics is not taught as an independent course or a stand-alone course but as part of an integrated curriculum. moral theories and related application are oriented vertically and horizontally along with relevant clinical topics. for example, core topics such as informed consent and confidentiality are introduced in year and revisited throughout the programme (vertical integration). other contentspecific topics such as ethical issues in human fertility are embedded into relevant learning block such as endocrine and reproductive health block in year (horizontal integration) and revisit in later years during clinical postings such as obstetrics and gynaecology (vertical integration). in terms of content, a wide range of topics is being covered. topics more commonly taught in pre-clinical years include principles of bioethics, history of medicine, origins and philosophy in ethics, and medical humanities. it is believed that these topics need an early introduction to help lay the foundation for bioethics education. some cases, such as the refusal of treatment, reproductive issues, paediatrics and neonatal issues, are very clinical and could be addressed at a later stage, e.g. during clinical postings. however, certain topics need to be emphasised throughout the medical programme. some examples are informed consent, patient-doctor relationship, privacy and confidentiality, health law, truth-telling, cultural issues and diversity awareness, religious and spiritual issues, conflicts of interest. these topics aim to prepare medical students for work readiness in the healthcare setting of a plural society like malaysia. bioethics was not a popular subject among medical students, in particular, among pre-clinical students. some faculty members also do not consider bioethics a 'real' topic to be taught. before the medical curriculum reform, the development of bioethics education was slow and insignificant. nonetheless, since embarking on the change via curriculum transformation in our undergraduate medical programme at the beginning of , our medical school has taken a giant step forward. murals related to bioethics on the walls of faculty buildings (figure ) , initiated by faculty members and completed by medical students, is testimony there is increased awareness and acceptance of the importance of bioethics education among faculty members and students. local setting hong kong, now a territory of china, was a former british colony from to and the british common law system continued after . british influence on the local medical practice and law also endures after the sovereignty handover to china. the current population of hong kong is about . million composed of chinese ( %). among the non-chinese ethnic groups, the majority are filipino ( %), followed by indonesia ( %), caucasian ( %), and others ( %) (the census and statistics department, ). compared with malaysia, hong kong is mostly a homogenous society. the medical council of hong kong is established under the medical registration ordinance handling the registration, professional conduct and discipline of medical practitioners in hong kong. the council also review the standard and structure of undergraduate medical education and training in the accreditation processes. in , the council updated the document "hong kong doctors", listing a set of essential attributes and skills in addressing the medical dilemmas and moral difficulties among local medical practitioners (the medical council of hong kong ). the chinese university of hong kong (cuhk) is one of the two local universities, providing a six-year undergraduate medical degree programme -bachelor of medicine and bachelor of surgery (mbchb). it offers comprehensive longitudinal doctoring curriculum to train physicians. at present, cuhk adopts conventional, studentcentred and subject-based curricula offered by the preclinical-clinical division. overview of the current medical curriculum the first three years of the mbchb curriculum encourage breadth and depth learning, offering pre-clinical studies focusing on interdisciplinary education in the field of humanities, social science, natural science. in addition to courses teaching fundamental biomedical courses relevant to medicine (e.g. public health, anatomy, physiology), students are required to courses humanities and language. before transiting to the clinical year, a six-week bridging course is in place to equip student pathology and clinical anatomy and clinical communications skills. the latter three years of studies focus on learning advanced biology and clinical medicine subjects, such as anatomical and chemical pathology, anaesthesia and intensive care, diagnostic imaging, clinical microbiology, medicine and surgery. students receive clinical exposure through a rich mixture of bedside teaching, simulation training, and community or laboratory research opportunities. courses for communication skills and professionalism are introduced throughout the entire six-year programme. the overarching objective of the medical curriculum is to provide an allrounded training of science and humanities (figure ). before the structured bioethics teaching rolled out, ethics was not yet implemented vertically and horizontally that sporadic ethics-related teaching took place on an ad hoc basis in the clinical years only. in , a workshop "integrated professionalism teaching session" was introduced for final year medical students as part of the induction towards independent clinical practice (joynt et al. ). it is a -h session comprises of lectures, small group discussions, and group presentations. the teaching topics broadly include the principles guiding professionalism, medical regulations and government ordinances. starting from , the quarterly clinical ethics grand round was also introduced in parallel in discussions about professional misbehaviours or ethical dilemmas in fig. coursework during the six-year mbchb curriculum at the chinese university of hong kong healthcare and life science. during the symposium, students and staff members are required to vote using a green-red card that encourages active and interactive participation. in this -h event, students identify key ethical issues that arise in the context of the case, discuss possible conflicting principles, and provide reasonable resolutions based on the four principles approach that underpins much of our teaching of ethics. with this framework, the teaching of bioethics in the medical schools was the focus in the clinical years only. the acquaintance of ethics knowledge in the pre-clinical year were less emphasised. starting from the mid- , the new bioethics curriculum is integrated into the curriculum, covering a wide range of ethical issues in biomedical sciences, clinical practice, public health, law, and policy. the teaching goal of bioethics education along three dimensions encompasses acquiring cognitive knowledge and behavioural skills and encouraging positive character development. besides, teaching modules are designed to raise ethical sensitivity and develop critical thinking skills while encouraging robust communication and interpersonal skills. in the clinical years, students can then link the ethical theory, knowledge, and examples taught in the preceding years for an application to the clinical context. table summarises the major themes of the curriculum. the topic-oriented approach in the pre-clinical year entails a teaching goal to ( ) observe inter-dependence between medicines and ethics, ( ) acquire bioethics knowledge and language, ( ) recognise vital ethical issues in medical practice, and ( ) apply reasoning skills when present in a dilemma. in the clinical years, students can then link the ethical theory, knowledge, and examples taught in the preceding years for an application to the clinical context. the section discusses barriers in the implementation of bioethics teaching from our experience, corroborating with literature. students' resistance to bioethics learning is a source of challenge. students, in general, believed that ethics is a 'soft' or 'fluffy' subject that lacks scientific rigour that could be reasoned based on common sensesocial and cultural normsthat does not require formal training (leo & eagen ) . malaysian and hong kong medical students, similarly, also regarded learning of ethics and medical humanities are of lower priority and prefer to spend more time learning clinical knowledge. ethics in medical education is sometimes regarded as a diversion from the core study of medical knowledge. at worst, ethics may be viewed as a tedious repetition of the obvious with an emphasis on procedural requirements for informed consent, protection of patient confidentiality, etc. less acknowledged is the unique role of bioethics in the development of core clinical skills such as critical reasoning, familial conflict management, navigation of discourse among professional peers, and understanding healthcare policy. the contemporary bioethics stems moral philosophy applied in research and healthcare contexts and the field has grown ever-present in medical curricula around the globe in an effort to produce doctors capable of navigating complex patient circumstances. however, given that most medical students gravitate towards hard science with its clear and testable answers, the theoretical-and humanities-based roots of bioethics reduce its importance in the eyes of pupils. another speculative reason is that students were uncertain about the need for bioethics in pre-clinical years, although they observe the vital role of bioethics for developing the professional identity. young medical students often neglected the importance of developing moral awareness for a future career during the time of learning 'skills' in early university years. interestingly, practising physicians observed the importance of bioethics when recognising their identity as primary caregivers as opposed to students (chan et al. ) . as young medical student progress to advanced years, they became interested in learning topics related to contemporary ethical issues and moral dilemmas that physicians faced in daily practice (aldughaither et al. ). the discrepant perceived view of bioethics education between young medical students and experienced practising doctors point out the need of a formal orientation about the instrumentality of bioethics training in early medical education years among students whose curricula in high school were predominately focused on mathematics, engineering and natural sciences. in other words, the influence of bioethics on professional identity construction has been largely ignored in reality. it is imperative to connect students with bioethics teaching such that relevance to the future career as a doctor is obvious rather than dismissed. there are studies in the united states, netherland, indonesia, or nigeria, reported that medical students witnessed unethical decision, unprofessional behaviour, inappropriate conduct by superiors or co-workers in early clerkship (muhaimin et al. ; okoye & nwachukwu ; seiden et al. ; yamey & roach ) . they, however, were uncertain about the resolution in preventing ethical lapses. importantly, implementing ethics training in the clinical years may be late, since students learn by being told what to do by senior doctors with limited opportunity to think and reflect critically (hren et al. ). bioethics training is not a one-time, but a longitudinal and reflective learning process in the career trajectory shaping a professional identity and cultivate a culture of humanism (fernandes ) . it needs to be implemented throughout medical practice years to help reconstruct correct values in medicine in the shifting role from 'layman or students' to 'physician' identity. when combined with traditional scientific learning, bioethics forms a critical component of comprehensive medical education, which has developed as the new international standard. to achieve parity with global education norms, bioethics teaching must adapt both to evolving learning styles and geographic realities. in the asia-pacific context, the euro-american dominance of teaching materials causes students to dismiss bioethics curricula as impractical. a lack of local contexts in the curriculum affects the long-term effect of learning. the framework should consider the deliberation of not only locally specific systems and events but also cultural belief systems and philosophical foundation of the society. modern bioethics which is developed in western philosophies might not adequately provide tools to address ethical complexity in clinical practices of ethical and religious diversity (chattopadhyay et al. ; fuscaldo et al. ) . the contested notion of cultural relativism in pluralistic societies as a response to the conventional belief of universality of morals needs to be discussed in bioethics education (sokol ) . the topic of public health is a great example illustrating the need to respect cultural difference from our experience. for instance, in the us context, the use of restrictive measures (i.e. quarantine) in response to infectious disease epidemics was disputable, as it is perceived to violate individual freedom for population good. this contrasts with hong kong, where citizens experienced the sars epidemic in , and using quarantine to monitor individuals for the 'greater good' was found reasonable from the local perspective (blendon et al. ) . in malaysia, the recent examples of covid- challenge the right in a religious gathering while implementing individual movement's restriction (yezli & khan ) . our recent transcultural experience introducing local topics cases has resulted in more lively discussions, with students more willing to express their observations and opinions on topics of bioethical relevance. for example, the discussion of imposing a mandatory influenza vaccination program for healthcare workers is somewhat less challenged in the us (babcock et al. ) . still, it remains unsettled in malaysia and hong kong, which results in a lively debate in the class (hudu et al. ; so et al. ) . these examples demonstrated that there is no unified approach to ethical problems, and responses are the result of a complex mix of moral and value-related issues turner ) . a study also discussed that incorporating cases that are relevant to the local medical systems helps cultivate bioethical responsiveness among the students . our learning experience is that placing local contexts as equally as western bioethics enhance the quality of a participatory bioethics teaching in our institutions and it should be done clearly at the design phase of the curriculum. one of the common challenges in the implementation of a bioethics curriculum in a resource-constrained context is a lack of teaching capacity (sim et al. ; ten have ) . teaching bioethics requires expertise both in ethics and medicine, and universities, nonetheless, have a limited ability to provide professional training of ethics and moral philosophy to sustain teaching quality. in the university of malaya, there is only a retired o&g specialist with a law degree, who is well-qualified to teach bioethics. other faculty members involved in bioethics teaching are mainly clinicians with some exposure to ethical issues in clinical practice but not trained specially in bioethics. in other malaysian medical schools, bioethics teaching is majorly lead by healthcare professionals or a multidisciplinary team of scientists, lawyers, and ethicists (sim et al. , bilgin et al. . in hong kong, many teachers who are involved in bioethics curriculum in medical programmes were either philosophers, ethicists, or scientists with limited experience in medicine, or clinicians with some training in bioethics (rothchild & holmquist ) . to address limited teaching capacity limitation, the faculty development team shall progressively organise workshops to provide training to faulty with little ethics background on areas such as how to integrate bioethics teaching into clinical postings. placing local contexts as equally as western bioethics will enhance the quality of a participatory bioethics teaching in asia, and it should be done clearly at the design phase of the curriculum. to overcome limited teaching resources, the success of the collaborative learning activities depended upon the training of local faculty who were responsible for leading the teaching. indeed, the concept of "training of trainers (tot)" has been widely implemented globally in the fields of health education by international institutions (e.g., un agencies) and major universities in developed countries in resource-limited settings, mostly developing countries (ewert et al. ; world health organisation, ) . unesco offers "ethics teachers' training courses (ettc)" in developing countries as part of its bioethics professional capacity building programme (ten have ; langlois ) . while tot can be effective to introduce the change in the place of intervention by teaching individuals, providing basic resources and implementing an initiative programme, another level of local resources is necessary to achieve sustainability (mormina & pinder ) . thus, the long-term effect of the bioethics curriculum requires the local commitment and leadership as resource-limited academic settings need more collaborative, participatory learning through interaction with teachers and peers in class (avci ). this paper described two evolving experiences in implementing bioethics teaching within existing institutional capacity. both medical schools are unique and very different in terms of the curriculum, and common challenges include curriculum design, students' resistance to bioethics teaching, and limited teaching capacity, were observed as the curriculum evolve. the reported experiences revealed that there is room for improvement regarding how medical schools integrate bioethics education. from a top-down approach, the faculty shall proactively improve teaching and educational quality by hosting continuous education sessions. from a bottom-up approach, it is equally crucially to empower students to raise awareness and concerns toward bioethics and helps students developing reasoning through challenging issues. student perspectives on a course on medical ethics in saudi arabia learning from experiences to determine quality in ethics education mandatory influenza vaccination of health care workers: translating policy to practice bioethics with chinese characteristics: the development of bioethics in hong kong what does it mean for a case to be "local"? the importance of local relevance and resonance for bioethics education in the asia pacific region pre-clinical students' views on medical ethics education: a focus group study in turkey attitudes toward the use of quarantine in a public health emergency in four countries: the experiences of hong kong, singapore, taiwan, and the united states are instructive in assessing national responses to disease threats learning needs in a medical curriculum in hong kong respect for cultural diversity in bioethics is an ethical imperative department of information, malaysia government medical ethics education in turkey; state of play and challenges training trainers in health and human rights: implementing curriculum change in south african health sciences institutions toward a culture of humanism: a proposal for the future of bioethics education in medicine enhancing cross-cultural understandings of ethical issues in medical education professional identity formation: creating a longitudinal framework through time (transformation in medical education) regression of moral reasoning during medical education: combined design study to evaluate the effect of clinical study years influenza vaccination among malaysian healthcare workers: a survey of coverage and attitudes medical students and professionalism -do the hidden curriculum and current role models fail our future doctors? the unesco bioethics programme: a review professionalism education: the medical student response an international survey of medical ethics curricula in asia a conceptual framework for training of trainers (tot) interventions in global health ethics education should make room for emotions: a qualitative study of medical ethics teaching in indonesia and the netherlands cultural considerations in forgoing enteral feeding: a comparison between the hong kong chinese, north american, and malaysian islamic patients with advanced dementia at the endof-life must we remain blind to undergraduate medical ethics education in africa? a cross-sectional study of nigerian medical students medical ethics education in india cross-cultural bioethics curriculum development: an example role of medical students in preventing patient harm and enhancing patient safety medical ethics education in china: lessons from three schools humanising medicine: taking our first step bioethics education in the medical programme among malaysian medical schools: where are we now knowledge, attitudes and practices on seasonal influenza vaccination among health care workers in hong kong bioethics education in a global perspective: challenges in global bioethics implementation of ethics education the census and statistics department, the government of the hong kong special administrative region from the local to the global: bioethics and the concept of culture evolution of bioethics education in the medical programme: a tale who training of trainers workshop with minitstry of health on strengthening emergency and essential surgical care at community health centres and primary health centre medical education in malaysia: quality versus quantity witnessing unethical conduct: the effects covid- social distancing in the kingdom of saudi arabia: bold measures in the face of political, economic, social and religious challenges publisher's note springer nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations authors' contributions jhs conceived the study. omyn and jhs drafted the manuscript. omyn made substantial edits on the writing. omyn and jhs approved the final manuscript.data availability not applicable. competing interests all authors declare no conflict of interests.code availability not applicable. key: cord- -ed tqn authors: wong, raymond s.m.; hui, david s. title: index patient and sars outbreak in hong kong date: - - journal: emerg infect dis doi: . /eid . sha: doc_id: cord_uid: ed tqn during the global outbreak of severe acute respiratory syndrome (sars) in , treatment was empiric. we report the case history of the index patient in a hospital outbreak of sars in hong kong. the patient recovered after conventional antimicrobial therapy. further studies are needed to address treatment of sars, which has high attack and death rates. s evere acute respiratory syndrome (sars), a new disease that is highly contagious, has caused a major impact worldwide. treatment of this disease remains empiric. this report describes the natural history of a case of sars in a young, previously healthy patient who received no specific therapy for infection with sars-associated coronavirus (sars-cov). he was the index patient in a large hospital outbreak in prince of wales hospital in hong kong ( ) . in early march , a -year-old man was admitted to a general medical ward of the prince of wales hospital; he had been ill for week with fever, chills, and rigor. he had had a cough productive of whitish sputum for weeks. he also had diarrhea and had vomited several times before his admission. his previous health had been good, and he had no history of recent travel. physical examination showed a temperature of . °c and bronchial breath sounds at the right upper zone lung field. chest x-ray confirmed right upper lobe consolidation ( figure, part a) . a complete blood profile on admission showed a leukocyte count . x /l, absolute neutrophil count . x /l, lymphocyte count . x /l, platelet count x /l, and hemoglobin . g/dl. the patient had mild renal impairment, with a creatinine of µmol/l, urea and electrolytes within normal limits, and alanine transaminase mildly elevated at iu/l (normal < iu/l). bilirubin, alkaline phosphatase, and albumin levels were normal. c-reactive protein was . mg/l (normal < . mg/l). a diagnosis of atypical or viral pneumonia was suspected because of the low leukocyte count and normal c-reactive protein. other laboratory tests were performed, including blood, sputum, and urine cultures, nasopharyngeal aspirate for influenza and parainfluenza, indirect immunofluorescence for respiratory syncytial viral antigen detection, and atypical pneumonia titer (for adenovirus, chlamydia psittaci, q fever, influenza a and b, and mycoplasma). the patient received treatment with intravenous amoxicillin-clavulanate and oral clarithromycin. the patient was housed in a general medical ward with no specific isolation facility. after admission his high fever and productive cough, now with thick, yellowish sputum, persisted. he also complained of progressive dyspnea, headache, dizziness, generalized malaise, and myalgia. his pulse and blood pressure were normal, and his oxygen saturation was approximately % on room air. a sputum culture yielded normal oral flora, and sputum smears were negative for acid-fast bacilli. nasopharyngeal aspiration was negative for influenza viruses a and b, respiratory syncytial virus, adenovirus, and parainfluenzavirus types , , and , with the use of commercial immunofluorescence assay. a chest radiograph on day showed progression of pneumonia, with consolidation changes over the right upper and lower lobes (figure, part b) . a repeat complete blood profile showed a leukocyte count of . x /l with persistent lymphopenia and a platelet count of x /l. amoxicillin-clavulanate was therefore changed to intravenous cefotaxime, g every h; clarithromycin ( mg twice a day) was continued. as the patient's condition deteriorated progressively and he had difficulty in expectorating sputum, salbutamol, . g four times a day, driven by a jet nebulizer at l of oxygen per min, was given to assist mucociliary clearance. his oxygen saturation remained normal without supplemental oxygen. starting from day , the patient's fever and chest condition gradually improved. however, over the next weeks, persons (mostly healthcare workers) who had been in contact with him had onset of a similar illness with high fever and pneumonia. the patient was subsequently con-firmed to be the index case-patient in this hospital outbreak of sars ( ). three family members were also infected. further history showed that he had visited a hotel in kowloon, hong kong, where a -year-old physician from southern china had stayed for days; this physician later died of severe atypical pneumonia days after admission to a regional hospital in kowloon ( ) . the cause of the illness was not known at the time of the physician's death. our patient was identified as the index case-patient days after the onset of this large outbreak at the prince of wales hospital, as he was the first patient who had the characteristic clinical, radiologic, and laboratory features of sars and had epidemiologic links with other infected persons. after days, use of the nebulized bronchodilator was stopped because of the possibility of enhancing sars transmission, and the patient was isolated in a private room with negative-pressure ventilation. healthcare workers entering the room wore disposable gloves and n masks. after the patient completed a -day course of cefotaxime and a -day course of clarithromycin, his pneumonia recovered gradually, and serial chest radiographs confirmed resolution of his consolidation (figure, part c) . his diarrhea and other systemic symptoms also resolved spontaneously. an immunofluorescence test for antibody against sars-cov subsequently confirmed an elevated titer of : , in convalescent-phase serum collected on day of illness. polymerase chain reaction of nasopharyngeal aspirate was negative for coronavirus. convalescent-phase serum was negative for other atypical pneumonia organisms, including adenovirus, c. psittaci, q fever, influenza a and b, and mycoplasma. repeat complete blood count showed that lymphocytes and thrombocytes had returned to normal, along with serum creatinine and alanine transaminase levels. the patient was isolated in a private room until day of his hospital stay, when his nasopharyngeal aspirate and urine samples were confirmed to be negative for sars-cov. repeat chest radiograph at follow-up weeks later showed no residual parenchymal opacity, and the patient remained asymptomatic. this report describes the index patient responsible for the hospital outbreak in the prince of wales hospital ( ). he was linked to spread of the virus to more than persons ( ). this outbreak, together with similar events in canada ( ), singapore ( ) and other cities where the source of infection was also related to the chinese physician ( ), led to increased awareness of this emerging global infection caused by a novel coronavirus ( ) a b c patient was related to failure to apply isolation precautions, as the disease had not been recognized during the early part of his admission. the use of a nebulized bronchodilator may also have enhanced the spread of the virus in the ward, and this practice was stopped for patients with suspected sars after this incident ( ). this case report illustrates the natural history of sars in a young, previously healthy patient who received no specific therapy. his clinical features and laboratory parameters were similar to those of other patients with sars ( ) ( ) ( ) ( ) . his clinical course followed a typical pattern with progression of pneumonia during the nd week of his illness ( ) . he was treated presumptively for bacterial community-acquired pneumonia with conventional antimicrobials ( ), without antiviral agents or corticosteroids. he started to improve by the rd week and subsequently recovered uneventfully. during the global outbreak in , treatment of sars was empiric. several groups have reported the use of ribavirin ( ) ( ) ( ) ( ) , ) and corticosteroids ( , , , , , ) with generally favorable outcomes. ribavirin has been associated with substantial adverse reactions, including hemolytic anemia, elevated transaminases, and bradycardia ( ) , and has demonstrated no in vitro activity against sars-cov ( ) . further studies, preferably with a randomized, placebo-control design, are needed to address treatment of this disease, which has high attack rates and is frequently fatal. the sars epidemic in hong kong a major outbreak of severe acute respiratory syndrome in hong kong clinical features and short-term outcomes of patients with sars in the greater toronto area severe acute respiratory syndrome (sars) in singapore: clinical features of index patient and initial contacts a cluster of cases of severe acute respiratory syndrome in hong kong identification of a novel coronavirus in patients with severe acute respiratory syndrome sars: experience at prince of wales hospital, hong kong clinical progression and viral load in a community outbreak of coronavirus-associated sars pneumonia: a prospective study guidelines for the management of adults with community-acquired pneumonia. diagnosis, assessment of severity, antimicrobial therapy, and prevention development of a standard treatment protocol for severe acute respiratory syndrome our strategies for fighting severe acute respiratory syndrome (sars) critics slam treatment for sars as ineffective and perhaps dangerous key: cord- -b yl mh authors: lau, joseph tf; griffiths, sian; choi, kai chow; tsui, hi yi title: avoidance behaviors and negative psychological responses in the general population in the initial stage of the h n pandemic in hong kong date: - - journal: bmc infect dis doi: . / - - - sha: doc_id: cord_uid: b yl mh background: during the sars pandemic in hong kong, panic and worry were prevalent in the community and the general public avoided staying in public areas. such avoidance behaviors could greatly impact daily routines of the community and the local economy. this study examined the prevalence of the avoidance behaviors (i.e. avoiding going out, visiting crowded places and visiting hospitals) and negative psychological responses of the general population in hong kong at the initial stage of the h n epidemic. methods: a sample of respondents was recruited in a population-based survey. using random telephone numbers, respondents completed a structured questionnaire by telephone interviews at the 'pre-community spread phase' of the h n epidemic in hong kong. results: this study found that . % of the respondents currently avoided going out or visiting crowded places or hospitals, whilst % felt much worried about contracting h n and % showed signs of emotional distress. females, older respondents, those having unconfirmed beliefs about modes of transmissions, and those feeling worried and emotionally distressed due to h n outbreak were more likely than others to adopt some avoidance behaviors. those who perceived high severity and susceptibility of getting h n and doubted the adequacy of governmental preparedness were more likely than others to feel emotionally distressed. conclusions: the prevalence of avoidance behaviors was very high. cognitions, including unconfirmed beliefs about modes of transmission, perceived severity and susceptibility were associated with some of the avoidance behaviors and emotional distress variables. public health education should therefore provide clear messages to rectify relevant perceptions. the who raised the influenza alert level to the highest pandemic 'phase ' level on june , . as of june , , , confirmed h n cases were detected in countries, territories and areas and deaths had been reported [ ] ; the number of death increased to , as of february , . a preliminary study showed that the new h n virus is more infectious than seasonal influenza [ ] . in hong kong, the first confirmed case, a traveler from mexico, was reported on may , , leading to the closure and isolation of the metropark hotel and to the quarantining of guests and staff from may l to may , . during the h n outbreak, the hong kong hospital authority raised the alert level to the highest 'emergency response level'. the government maintained its confinement strategy till june, , when it became obvious that cases were spread in the community, and the response thus became mitigation. as of june , , there are confirmed cases in hong kong and no h n -related death was recorded and as of february , , there were h n -related deaths. the lessons learned from the sars experience in hong kong [ ] and other countries demonstrated the importance of understanding community responses [ , ] . surveillance of community responses at the initial phase of an emerging epidemic is useful to inform both policy makers and the public about the state of preparedness. in hong kong, at the time of the sars epidemic, the perceptions and behaviors changed dramatically during the course of the outbreak [ , [ ] [ ] [ ] . panic and worry increased and became widespread during the epidemic and remained high in the post-sars period [ , ] . at the height of the epidemic, the general public avoided going out, traveling to other countries and gathering for social activities [ ] . scholars estimated that a loss of hk$ billion in spending on goods and services in hong kong domestic economy was attributable to the sars epidemic [ ] . similar studies were conducted to investigate community responsiveness to the threat of human-to-human h n avian flu transmissions in hong kong [ ] [ ] [ ] [ ] . previous studies on human avian flu or sars in different countries also suggested that widespread distress occurred in affected areas and nationwide populations even at the early phase of the outbreak, causing serious social and economic disruption [ , ] . a study was conducted to investigate community behavioral and emotional responses at the very initial phase after the identification of the first few h n cases in hong kong [ ] . a few other studies have investigated community's attitudinal and behavioral responses toward the early phase of the h n pandemic in countries including the u. k. [ ] , australia [ ] , malaysia and europe [ ] , france [ ] , japan [ ] . avoidance behaviors have been prevalent in a number of countries or cities, such as hong kong and malaysia but not in the u. k. mild emotional distress was observed in hong kong but the public in japan perceived overwhelming fear. the majority of the respondents in the hong kong study washed their hands more often than usual, but only around % of those in the u. k. did the same. variations in perceived susceptibility and perceived efficacy over preventive measures have also been reported in these studies. therefore, community responses to the h n pandemic are likely to be country-specific, possibly determined by previous experiences of epidemics such as sars, the health system, risk communication patterns and even culture [ ] . this study investigated whether the general population in hong kong avoided visiting different places (going out, visiting crowded places and visiting hospitals) and assessed some negative psychological responses to h n , including whether people were much worried about contracting h n and their level of emotional distress (panicking, depression or emotional disturbance) due to h n . factors in association with the outcome variables on avoidance behaviors and negative psychological responses were investigated, including variables such as socio-demographic characteristics, confirmed knowledge and unconfirmed beliefs about modes of h n transmission, evaluation towards governmental preparedness/ performance, perceived availability of treatment, and risk perception (perceived severity and susceptibility related to h n ). the study period of this report covers almost the entire pre-pandemic and pre-community outbreak phase of the h n epidemic in hong kong. the study population comprised all chinese adults who were years old or above in hong kong. anonymous telephone interviews were conducted by well-trained interviewers, using an identical structured questionnaire, from may to may (day - , n = ), from may to may (day - , n = ), and from june to june (day - , n = ), . there were respectively , and imported cases (and no community non-imported cases) detected at the beginning date of these surveys. preliminary data from the survey conducted from may to may have previously been reported [ ] . the first local community-infected case with an unknown source of infection was reported on june , , so that the surveys (may to june , ) therefore covered almost the entire 'pre-community outbreak phase' (may to june , ) of the local epidemic. random telephone numbers were selected from an up-to-date telephone directory and the last two digits of the selected telephone number were randomized to include some unlisted telephone numbers; over % of the households in hong kong have a fix-line telephone at home [ ] . the interviews were conducted from : to pm to avoid overrepresenting the non-working population. one member was selected by the last-birthday-rule from each of the contacted households. at least phone calls were made at different hours and days before an unanswered number is considered invalid. verbal consent was sought and the study was approved by the ethics committee of the chinese university of hong kong. a total of , phone numbers were made and being answered by someone ( , calls were unanswered with at least attempts made), out of which , were eligible households were identified and being invited to join the study. of these , eligible respondents, ( . %) could not be contacted after attempts, ( . %) refused to join or withdrew from the study, and ( . %) participated in the study. previously, preliminary data from the may to may survey have been reported elsewhere [ ] . dependent variables included current avoidance behaviors: ) 'avoided going out', ) 'avoided visiting crowded places' and ) 'avoided visiting hospitals', and exhibition of negative psychological responses: ) worried very much that oneself or one's family would contract h n and ) emotional distress ('panicking very much' or 'felt much depressed' or 'felt much emotionally disturbed' due to h n ). socio-demographic characteristics were recorded. correct knowledge and unconfirmed beliefs about modes of h n transmission were assessed. respondents were asked about perceived availability of treatment. risk perception questions include those related to perceived severity of h n (fatality and severe irreversible bodily damages), the relative chance for hong kong to have a large-scale h n outbreak as compared to other countries, and perceived susceptibility (oneself, one' family and the general public). questions were also asked to evaluate relevant actions taken by the government ( items), their ability to control the epidemic ( items), as well as the health system's preparedness toward the h n pandemic ( items: adequacy of medicine, vaccines and personal protection equipments). these items are listed in tables , and . they were modified from the questionnaires which had been used in some avian flu studies [ ] [ ] [ ] [ ] and sars studies [ , , , ] . they have also been used in the published baseline h n study [ ] . associations between the independent variables and the dependent variables (avoidance behaviors and negative psychological responses) were assessed by using univariate odds ratios (or) and their respective % confidence intervals (ci). variables that were significant in the univariate analysis were used as candidates for fitting logistic regression models. multivariate or and their % ci were reported. spss . was used for the data analyses with p < . as the level of statistical significance. of all respondents (n = ), . % were males; . % were of age years old or above; . % received some post-secondary education; % were currently married or were cohabitating with someone; % were currently employed full time; and . % were health care workers. the age and gender distributions did not vary across the surveys and were similar to those of the census data (footnote of table ). of all respondents, . % held at least one of the unconfirmed beliefs that h n could be transmitted through airborne spread across long distance (e.g. from a building to another building; . %), via water sources such as reservoirs ( . %), via insect bites ( . %) or via eating well cooked pork ( . %). respectively, . %, . % and . % of the respondents correctly knew that h n is transmittable via droplets, touching the body of infected person or contaminated objects; about . % were correct in all these three items ( table ) . around - % of all respondents believed that the local health system currently did not have enough medication ( . %), vaccine ( . %) or personal protection equipments ( . %) to deal with the h n epidemic, with . % holding at least one of such beliefs ( table ). the majority ( . %) of the respondents was confident in the public's or governmental ability to control the epidemic, i.e., either agreeing with the statements 'hong kong would be able to control the h n epidemic' ( . %) or with the statement that the 'hong kong government would be able to control a large-scale h n outbreak' ( . %). the majority ( . %) of the respondents gave a passing score > for the governmental performance in dealing with h n (range = to , with as the passing mark; table ). about % ( . %) of the respondents believed that there was so far no effective drug available to treat h n ( table ) . around % of the respondents believed that h n is highly fatal ( . %) or could cause severe irreversible bodily damages ( . %; table ). respectively, . % and . % believed that hong kong has a higher or a lower chance of having a large scale h n outbreak in the future year, as compared to other countries. close to % of the respondents perceived a high or very high chance for himself/herself ( . %), his/her family members ( . %) or the general public ( . %) to contract h n in the next year ( table ) . respectively . %, . % and . % of the respondents currently avoided going to crowded places, avoided going out or avoided visiting hospitals. around % ( . %) of the respondents were currently much worried that either they or their family members would contract h n ; . % showed signs of emotional distress (i.e. panicking very much or felt much depressed or were very much emotionally disturbed due to h n ). females, older respondents, those with >= unconfirmed beliefs about modes of h n transmission, those who knew that h n could be transmitted 'via droplets', 'bodily contact with infected person' or 'touching contaminated objects', those who were very worried that either they or their family members would contract h n , those expressing emotional distress (in panic or feeling very depressed or being highly emotionally disturbed due to h n ) were more likely than others to avoid visiting crowded places (multivariate or = . to . , p < . ; table ). females, older respondents, those with >= unconfirmed beliefs about modes of h n transmission, those who knew that h n could be transmitted 'via droplets', 'bodily contact with infected person' or 'touching contaminated objects', those who believed that h n would cause severe irreversible bodily damage, and those expressing emotional distress (in panic or feeling very depressed or being highly emotionally disturbed due to h n ) were more likely than others to avoid going out (multivariate or = . to . , p < . ). those who were full-time employed were less likely than others to avoid going out (multivariate or = . , p < . ; table ). the respondent . % family members . % the general public . % * governmental performance was assessed by items: timeliness of measures taken; effectiveness of implemented measures; clear explanations made to citizens; adequacy of implemented measures; coordination across governmental departments; overall performance of the government. (score range = to , with as the passing mark). an average was calculated for the item scores. # less than % missing cases exist for the listed variables. (score range = to , with as the passing mark). an average score was calculated for the item scores. variables that were not significantly associated with any of the dependent variables in the univariate analysis were not tabulated. these variables include being current health care practitioner, perceived availability of drugs, perceived high chances of contracting the disease for himself/herself, his/her family members and the general public. respondents who were married/cohabited, those with >= unconfirmed beliefs about modes of h n transmission, those who believed that h n would cause severe irreversible bodily damage, and those who were very worried that either they or their family members would contract h n were more likely than others to avoid visiting hospitals (multivariate or = . to . , p < . ; table ). the results of the multivariate analysis showed that those who believed h n would cause severe irreversible bodily damage and those who believed that they themselves had a high chance of contracting h n were more likely than others to be much worried that either they or their family members would contract h n (multivariate or = . and . respectively, p < . ; table ). those who believed either that the general public and/or the local government would be able to control a large scale local h n outbreak were less likely to show the worry (multivariate or = . ). in the multivariate analysis, females, those who doubted about adequacy of governmental preparedness (inadequate vaccine or medication or personal protection equipments in hong kong), those who associated h n with a high fatality, and those who believed that their family members had a high chance of contracting h n were more likely than others to indicate emotional distress (panicking or much depressed or much emotionally disturbed) due to h n . the significant multivariate or ranged from . to . (p < . ; table ). around % of the respondents showed some avoidance behaviors. the studies covered the entire early 'pre-community outbreak phase' of the h n epidemic in hong kong during which all confirmed cases were imported. during the study period, the local government had not given any public health advice about avoiding going to different places, though a previous analysis of our may to may data showed that . % of the public misconceived that such an advice was given [ ] . avoidance of visiting hospital may be due to the fear of getting infected in hospitals, which was prominent during the sars period [ ] . the government only started advising people to avoid crowded places at the 'community outbreak phase' of the epidemic. there seemed to be no serious immediate public health threat for going out or visiting different places. such avoidance behaviors were associated with negative psychological responses; emotional elements may therefore be strongly involved in making the decisions. experience from sars showed that such avoidance behaviors among large numbers in the popula-tion potentially damages the economy and disrupts daily lives. about half of the respondents believed that hong kong has a lower chance of having an h n outbreak as compared to other countries, whilst only less than % held the opposite belief. there were signs of underestimating the risk of having a community outbreak in hong kong [ ] . the shift into the pandemic phase as announced by the who and the explosion of non-imported community cases in hong kong ( as of june , ) may change the picture completely. the direction of change is however uncertain. a few international studies also documented strong levels of anticipated anxiety and avoidance behaviors at the early phase of human avian flu outbreaks or pandemic influenza [ , [ ] [ ] [ ] . the impact of pandemics and unknown emerging infections has not been widely studied. avoidance behaviors and emotional distress may have been under-emphasized in the preparedness plans. it is seen that females, older people and those who were not full-time employed were more likely than others to show avoidance behaviors or signs of emotional distress. the results are consistent with those reported during the sars period [ ] . a recent study exploring people's emotional and behavioral responses to an avian flu outbreak also showed that females and older people were, respectively, more likely to express negative emotional responses and exhibit avoidance behaviors (e.g., avoiding leaving their residence, avoiding crowds and avoiding visiting hospitals) in response to avian flu [ ] . attention should therefore be given to avoidance behaviors and psychological needs of these subpopulations at times of a pandemic. perceptions still count in this context. there were substantial unconfirmed beliefs about the mode of h n transmission ( . % had at least one unconfirmed belief ). around / of the respondents did not know that the virus could be spread by touching contaminated objects. the aforementioned unconfirmed beliefs about transmission mode were significantly associated with avoidance behaviors. unconfirmed beliefs about modes of transmission were also documented in h n studies [ ] , suggesting that similar unconfirmed beliefs exist in general for emerging respiratory infectious diseases. rectification of misconceptions is important -and may decrease and reduce unwarranted anxiety. around % of the respondents believed that h n would result in high fatality or severe irreversible bodily damages. such beliefs may be affected by the sars experience. perceived high fatality was associated with emotional distress (e.g. panic) due to h n and perceived severe irreversible bodily damage was associated with of the outcome variables on avoidance behaviors and negative psychological responses. up-to-date informa- tion about the clinical properties of h n should be disseminated to the public in layman terms. the actual fatality associated with h n , both local and international, remains low. the cost of assurance by hong kong government is however, high -with early summer closure of all primary schools and kindergarten and a number of secondary schools, billion hong kong dollars being spent ( . billion us$) to purchase h n vaccines and reorganization of the health services to accommodate escalating infection figures are not insubstantial. tourism may be adversely affected. a substantial proportion of the public may be overestimating its fatality and physical damages. since public understanding of risk and of these mitigation measures will help to reduce unnecessary concern and changes in lifestyle amongst the population, public education is important. as expected, perceived personal/family susceptibility for contracting h n was associated with negative psychological responses due to h n . the association between perceived personal/family susceptibility and avoiding going out was non-significant. the results suggest that the public did not avoid going out because of feeling susceptible. avoidance behaviors may involve an irrational element. it is speculated that the sars experience of avoiding going to different places [ ] might have a spill-over effect. the general public evaluated the government highly in the performance and ability to control the pandemic. they however, showed reservations about the availability of medicine and vaccine and protective equipments, possibly because h n was a new disease and it was not certain whether effective medicine, vaccine and equipments were then available. the positive evaluations of governmental performance and perceived ability for hong kong or the government to control the h n outbreak were significantly associated with the outcome variables in most of the univariate analyses. nonetheless, most of these associations were statistically non-significant in the multivariate analysis. the associations between such variables and the outcome variables (avoidance behaviors and negative psychological responses) were hence mediated by other variables, such as worry about contracting h n or perceived susceptibility. these potential mediators were multivariately associated with either the avoidance variables or the negative psychological response variables. the study has some limitations. first, this was a crosssectional baseline study. second, the response rate was comparable to those of other relevant published studies but some non-responder bias may still exist [ , , ] . some telephone numbers are unlisted and we randomized the last two digits to cover some of the unlisted numbers. moreover, the gender and age distributions were comparable to those of the census population data. third, results were self-reported and social desirability bias may exist. the study was however anonymous. fourth, hong kong went through unique sars experience, the results may not be comparable with those of other countries. fifth, the measures on negative psychological responses were based on those used in previous studies, rather than derived from some validated scales. finally, the study was not intended to track changes within the short study period of a month -interactions between time and various independent variables were not explored. similar data obtained from other countries are becoming available and can be compared with ours. in sum, the results of this study documented that a noticeable proportion of the public exhibited avoidance behaviors that had not been advised by the government and negative psychological responses at the early 'precommunity outbreak phase' of the h n outbreak. with the relatively mild nature of the h n , and with all the hygiene and public health measures continually reemphasized, an open debate on whether the public should avoid going out during the h n outbreak should be encouraged. it would facilitate appropriate responses and daily lives of people in hong kong, one of the most densely populated cities in the world, remain undisrupted. the study is part of an ongoing surveillance program, which is in place in hong kong. hong kong is now in the pandemic and 'community outbreak phase'. the public needs to be better informed about the modes of transmission and clinical consequences of the disease to make rational behavioral choices. early detection of mental health problems and primary preventions are warranted. comparisons with other parts of the world, such as mainland china, would be very informative. this study provides a better understanding of the factors associated with negative psychological responses due to h n , which would give useful insights to designing primary prevention of mental health distress at the initial phase of this and outbreaks of other emerging respiratory infectious diseases. the opinions expressed by authors contributing to this journal do not necessarily reflect the opinions of the centre for health behaviours research or the institutions with which the authors are affiliated. world health organization: influenza a(h n ) -update who rapid pandemic assessment collaboration: pandemic potential of a strain of influenza a (h n ): early findings severe acute respiratory syndrome(sars) expert committee: sars in hong kong: from experience to action monitoring community responses to the sars epidemic in hong kong: from day to day a tale of two cities: community psychobehavioral surveillance and related impact on outbreak control in hong kong and singapore during the severe acute respiratory syndrome epidemic the impact of community psychological responses on outbreak control for severe acute respiratory syndrome in hong kong factors influencing the wearing of facemasks to prevent the severe acute respiratory syndrome among adult chinese in hong kong longitudinal assessment of community psychobehavioral responses during and after the outbreak of severe acute respiratory syndrome in hong kong sars-related perceptions in hong kong. emerging infectious diseases economic impact of sars: the case of hong kong a serial of surveillance surveys of anticipated behavioral and psychological responses to avian influenza pandemic in humans among the hong kong general public (sf- ). oral presentation at the th apacph annual conference perceptions about status and modes of h n transmission and associations with immediate behavioral responses in the hong kong general population anticipated and current preventive behaviors in response to an anticipated human-to-human h n epidemic in the hong kong chinese general population perceptions related to human avian influenza and their associations with anticipated psychological and behavioral responses at the onset of outbreak in the hong kong chinese general population differences in public emotions, interest, sense of knowledge and compliance between the affected area and the nationwide general population during the first phase of a bird flu outbreak in israel crisis prevention and management during sars outbreak widespread public misconception in the early phase of the h n influenza epidemic public perceptions, anxiety, and behaviour change in relation to the swine flu outbreak: cross sectional telephone survey the community's attitude towards swine flu and pandemic influenza swine flu") lay perceptions of the pandemic influenza threat responses to the outbreak of novel influenza a (h n ) in japan: risk communication and shimaguni konjo a population-based study of depression and three kinds of frequent pain conditions and depression in hong kong impacts of sars on health-seeking behaviors in general population in hong kong prevalence and factors of sexual problems in chinese males and females having sex with the same-sex partner in hong kong: a population-based study predicting the anticipated emotional and behavioral responses to an avian flu outbreak pandemic influenza in australia: using telephone surveys to measure perceptions of threat and willingness to comply realities and enigmas of human viral influenza: pathogenesis, epidemiology and control sars preventive and risk behaviours of hong kong air travellers an outbreak of the severe acute respiratory syndrome: predictors of health behaviors and effect of community prevention measures in hong kong the authors would like to thank all participants of this study. thanks are extended to mr. nelson yeung for his help in the early drafts of the manuscript, mr. tony yung and mr. johnson lau for their assistance in the preparation of the questionnaire, ms. mw chan, mr. mason lau, and ms. cheri tong for coordination of the telephone survey and all colleagues who served as telephone interviewers of this study. the study was supported by the research fund for the control of infectious diseases from the food and health bureau. the authors declare that they have no competing interests. jtfl designed and oversaw the study and wrote the manuscript. sg and hyt proposed suggestions to improve study and revised the manuscript intellectually. kcc performed the data analysis. all authors read and approved the manuscript. the pre-publication history for this paper can be accessed here: key: cord- -n ywei t authors: keck, frédéric title: avian preparedness: simulations of bird diseases and reverse scenarios of extinction in hong kong, taiwan, and singapore date: - - journal: j r anthropol inst doi: . / - . sha: doc_id: cord_uid: n ywei t this article describes relations between humans, animals, artefacts, and pathogens in simulations of disasters, taking bird diseases in three chinese sentinel posts as ethnographic cases. drawing on distinctions between simulation, ritual, and play, it shows that the engagement of actors in the imaginary of simulations, which they describe as ‘realism’, reflectively reverses the oppositions between humans and nonhumans, active and passive, fiction and reality that shape ordinary life. borrowing from the anthropology of hunting societies, it argues that simulations of bird diseases, considered as signs of future species extinction, rely on cynegetic techniques of power, in which humans and animals symmetrically shift perspectives, and not only on pastoralist techniques, in which humans are above the population they monitor and sometimes sacrifice. of action, simulations can be described as ritual performances displaying relations between humans and nonhumans in extraordinary settings. this article starts from observed simulations of an avian influenza pandemic in china. influenza viruses emerging from birds have been considered as potentially causing future pandemics, because birds (particularly waterfowl in south china) have been identified as the reservoir in which flu viruses mutate before spreading successfully between humans (shortridge & stuart-harris ) . among other techniques such as early warning systems and stockpiling vaccines, preparing for the next pandemics therefore involves simulating the transmission of pathogens from birds to humans (caduff ; lakoff ) . arguing that a human pandemic is a symmetrical threat to the extinction of a bird species, i then consider another bird disease for which chinese experts organize simulations: botulism. this disease, which doesn't affect humans, is considered a potential disaster for black-faced spoonbills because it kills migratory birds when they concentrate in wetlands on their flyways (wilson : ) . bringing together simulations of avian influenza and botulism, this article questions the ethnography of simulation from the perspective of animal studies. how does preparedness transform relations between humans and birds? what does it mean to include birds, and more generally animals, in exercises simulating coming disasters? how does the description of animals as victims of disasters transform them into actors of simulations (keck & ticktin ) ? i will show that animals become, in a paradoxical way, 'passive actors' when they carry the signs of diseases that can potentially affect humans. techniques of preparedness have been included in the set of tools for global health initiatives, either in humanitarian actions or in biosecurity interventions, which have shaped contemporary affects and anticipations of the future (adams, murphy & clarke ; lakoff ) . global health has been extended to animals and the environmentan approach called 'one world, one health' -thus requiring an interspecies approach towards the ethical issues involved (hinchliffe ) . one of the most debated questions in the anthropology of pandemic preparedness is the adequacy of the notion of sacrifice to describe how some populations are separated from others and killed or left to die for the sake of public health. in exercises of triage, some patients are prioritized over others through the framework of urgency (nguyen ; redfield ) . in the management of human populations, migrant workers are considered as a threat by educated experts using viral connectivity as a metaphor of modernity (macphail ; mason ) . in the management of zoonotic pathogens, the notion of sacrifice seems even more obvious, since animals are massively killed to eradicate the reservoir of emerging infectious diseases; and in the management of wild animals, some individuals are sacrificed to protect the species (van dooren ). other descriptions, however, have been proposed of the entangled relations between animals and humans in the 'hotspots' or 'sentinel devices' where emerging pathogens connect them in productive ways (brown & kelly ; fearnley ; keck & lakoff ; lezaun & porter ; lowe ) . while sacrifice separates some living beings from others to eradicate pathogens, sentinels instantiate relations between living beings through the anticipation of future pathogens. simulations of bird diseases shift perspectives between humans and animals through the use of fiction. to support this argument, i rely on the anthropology of hunting societies, by contrast with pastoral societies. while public health relies on pastoral techniques of power combining sacrifice and surveillance to contain the threats coming from outside in a population (foucault ) , the 'one world, one health' approach uses techniques from birdwatchers and wildlife managers to monitor data about changing relations between humans and animals. whereas pastoral techniques are asymmetrical, relying on the pastor's superior gaze over the flock manifested by sacrifice, cynegetic techniques are symmetrical, as hunters and prey constantly change perspectives when displayed in rituals (chamayou ) . most analyses of simulation have placed it in a genealogy starting with the cold war, using notions of ritual, performance, and play (davis ; galison ; gusterson ; lakoff ; masco ) . but they don't take the perspective of animals because they consider simulations as pastoral techniques of biopower, therefore bypassing what the anthropology of hunting societies shows about ritual action. in this article, i define a cynegetic practice of simulation that is always mixed with forms of planning, combining two different forms of anticipation. i call 'avian preparedness' this mix of cynegetic becoming-animal and pastoralist care for populations initiated by microbiologists, considered both as 'virus hunters' (perrey ) and as 'microbe farmers' (caduff : ) . to analyse simulations of bird diseases, i combine the notion of reverse scenario (schull ) with the notion of reflexive ritual. pandemic or extinction scenarios, i argue, connect humans and animals in realistic ways to play on the imagination of what could happen if a pathogen emerges. using animal reservoirs as mirrors in which anxieties about pandemics are reflected, humans exchange their perspectives with animals in an imagined future where their relations are reversed. simulations can thus be situated in an anthropological space between play and ritual. roberte hamayon ( : ) has called 'simulation' the way shamans in mongolian hunting societies imitate the movements of animals in a ritualized setting to prepare for the uncertainties of hunting. in an article entitled 'dissimulation and simulation as forms of religious reflexivity' , michael houseman proposes to move away from a definition of ritual as a collective action based on a shared secret to study 'the emergent properties of ritual simulation generally ' ( : ) . he draws on two cases taken from hunting societies of central africa, one in which male novices are symbolically killed and the other in which a goat is actually sacrificed. he asks: how do participants come to believe in a series of speeches and actions -the novice's death and the goat's consent to sacrifice -that are obviously false? he answers that ritual action creates an extraordinary space of reflexivity with regard to the ordinary relations that constitute the group. while the ritual for male novices is a 'dissimulation' , in which the relations between initiated and uninitiated are constantly reversed in such a way that the moment of death becomes uncertain, the ritual of goat sacrifice, says houseman, is a simulation of consent, in which the silencing of the goat through the consumption of herbs mimics the consent of male hunters to their initiation. the ritual is reflexive in the sense that it stages the condition of the ritual itself -the secrecy known by initiators and unknown by the initiatedthrough the manipulations of daily relations between humans and nonhumans, whose asymmetries are reflected as in a mirror. similarly, i suggest that we call 'reverse scenarios' the ritual performances by which simulators reflect playfully on the relations between humans and birds in the imagination of a disease that could affect them both. simulations, i argue, are far more than mere 'rehearsals' of a pandemic drama: they are catalysts in the transformation of human/nonhuman relations into asymmetrical biopolitical and ontological processes. to support this argument, i will describe three ethnographic cases in hong kong, taiwan, and singapore. these three territories have competed at the global level since the sars crisis in to be the best 'sentinel posts' where pandemic pathogens coming from china can be detected (abraham ) . as hubs for the intense circulation of persons and commodities in asia, but also as repositories of chinese traditional relations between humans and birds, they have prepared for the catastrophic effects of a bird flu outbreak. but while the hong kong government regularly culls its poultry and sends warning signals from the chinese border, taiwan and singapore rarely had to cull their poultry and rather invested in scenarios for the simulation of pandemic. taiwan, on the other side, shares with hong kong the monitoring of black-faced spoonbills, considered as one of asia's most threatened and charismatic species. this article thus connects the rationalities of preparedness with the economies of human/animal relations in three different but interconnected settings. it will examine indoor and outdoor simulations of avian influenza in singapore and hong kong, and compare them with simulations of botulism in taiwan. however, my analysis is not restricted to simulations of bird diseases in east asia, but highlights general traits of disaster simulation as a technique of preparedness. by looking at the relations between humans and birds in these three contexts through their common exposure to emerging pathogens, this article also analyses the relations between national states in asia as they have to manage a common disaster. since simulations of bird diseases connect relations at different scales, from the microbiological to the biopolitical, this article combines science studies, ethnography of rituals, and political economy through an anthropology of 'more-than-human' relations (helmreich & kirksey ; kohn ; sagan ) . in july , i was visiting gavin smith, who was then an associate professor at the duke graduate medical school of the national university of singapore (nus). i had known gavin in hong kong while he was working in the state key laboratory of emerging infectious diseases at the department of microbiology of the university of hong kong. born in australia, gavin had studied botany and ecology at the university of melbourne, and then moved to hong kong for a ph.d. in molecular systematics. gavin had first analysed the genome of fungi, then of the sars coronavirus, then of bird flu viruses. he described this development of his research as a reduction of the size of the living beings he was sequencing, and a refinement of the data and results he could produce. gavin and his team relied strongly on the collaboration between the state key laboratory of emerging infectious diseases and the university of shantou. this university had been created by the hong kong tycoon li ka-shing, who opened it in in his native guangdong, with the approval and administrative support of the chinese authorities. it provided the state key laboratory of emerging infectious diseases with samples collected in poultry markets in fujian province, thus offering a real-time surveillance of influenza strains emerging in this 'epicentre' of pandemic flu. but after the publications of gavin's team showed the role of the chinese poultry industry in the emergence of these new strains (smith et al. ) , the guangdong authorities had severely restricted hong kong virologists' access to these samples. gavin then moved to singapore in , where he had more freedom to continue his fundamental research, and more funding from international institutions. he had shifted from the sentinel post, where the new strains of avian influenza emerged, such as the h n virus in (keck ) , to a place where he could simulate the evolution of flu viruses in high-tech computers. there was no need to be close to the site where viruses emerge, he explained to me, as he could simulate viral emergence through the use of genetic data banks. singapore was then considered the new 'pole of excellence' for biological research. the small city-state founded by lee kwan yew in at the end of the malay peninsula had converted its industrial and financial power, owing to its position on the commercial trade routes between east and west, into an economy of knowledge and information, with high investment in biotechnologies (ong ; ) . the nus graduate medical school was located just next to the ministry of health and the singapore general hospital, in the centre of the city. it had been created in to train high-tech medical leaders on the model of the duke university school of medicine in north carolina. the programme in emerging infectious diseases, for which gavin had been hired to work, was headed by wang linfa, who was also leading a team on bat viruses at the australian animal health laboratory in geelong. his programme was running projects for the surveillance of emerging infectious diseases, particularly influenza and other respiratory diseases, in singapore and the rest of southeast asia. gavin's career took a meaningful turn when his team published two major articles at the height of the h n pandemic. the first one, entitled 'dating the emergence of pandemic influenza viruses' , was published just after the emergence of the h n virus in mexico in april . it showed that genetic components of the h n pandemic virus circulated among pigs and humans as early as , thus challenging the commonly held view that spanish flu jumped from birds to humans in . in the context of the new h n 'swine flu' , this article stressed the need for intensified surveillance of pigs to detect emerging flu viruses before they become pandemic. 'if future pandemics arise in this manner' , gavin and his team concluded, 'this interval may provide the best opportunity for health authorities to intervene to mitigate the effects of a pandemic or even to abort its emergence' (smith, bahl, vijaykrishna, et al. : ) . this conclusion was immediately reinforced by gavin's team's second publication, entitled 'origins and evolutionary genomics of the swine-origin h n influenza a epidemic' , published in nature at the end of , in which they showed that a 'twin' virus bearing the same genetic sequence as the pandemic h n had been identified in pigs in hong kong in . gavin's conclusion was not that the asian swine industry was to blame for the emergence of h n , but that there was a better surveillance of the animal reservoir for influenza viruses (waterfowl and pigs) in hong kong than in the united states. the team's paper ended, 'despite widespread influenza surveillance in humans, the lack of systematic swine surveillance allowed for the undetected persistence and evolution of this potentially pandemic strain for many years' (smith, vijaykrishna, bahl, et al. : . in july , i took a course at the hong kong university pasteur research centre in bioinformatics, during which gavin and his team partners, vijay and justin, explained to virology students how to obtain this kind of result. bioinformatics is a method to analyse the massive amount of biological data available on the web -particularly through the website of the us national center for biotechnology information, genbank -with the help of dedicated software. this software, called blast (basic local alignment search tool) or msa (multiple sequence analysis), calculates the probability that genetic sequences derive from one another. such a procedure, called alignment, aims at approximating the real descent relationships between viruses through a calculation of the optimal 'tree of life' , based on the darwinian hypothesis that life expands in a rational manner to maximize fitness capacities (mackenzie ) . for gavin and his team, however, bioinformatics was not only about probability calculation. in the construction of a phylogenetic tree, biological knowledge is necessary because some correlations proposed by the computer make no sense in an evolutionary perspective, as they can be due to errors in sequencing or genetic deletion. to decide which correlations to take into account and which to consider as irrelevant, virologists use other software (such as bootstrap, jukes cantor, or tamura) providing the probability of correlations based on a given scenario. as for other techniques of preparedness, probability is not enough to simulate a coming disaster: it requires a work of imagination (lakoff ) . peter galison has shown that computer simulation emerged in the field of particle physics as a 'subculture' among experimenters and theoreticians under the 'monte carlo' programme funded by nasa in the s to simulate a nuclear explosion. simulation replaces experimentation when the data needed for the theory are too numerous and complex to be processed with traditional instruments, creating a 'trading zone' in which different professional groups share a common language or 'pidgin' (galison : ) . similarly, bioinformatics produces new images shared by microbiologists, computer scientists, and public health executives in the anticipation of epidemics. software such as bootstrap can be considered as an accessory or decoy to trap the live bird viruses through the sequences that have been stored in genbank. gavin opened the course with a simulation of the work his team had done a few months before on the h n virus, presented as a desktop exercise of what to do when a new virus emerges. 'imagine we've received this new sequence from atlanta. paste it to blast, and take as much information as possible. make a tree so big you can never print it on a sheet of paper: it will be good starting material before reducing the inquiry' . gavin and his team explained that in contrast to other virologists working on flu viruses, they had decided to use the eight segments of the virus's rna, not just the two segments that shape the h and n proteins, usually considered to be the most significant markers of antigen evolution. they could thus build eight parallel evolutionary trees which, by their similarities, gave an indication of the real evolution of the whole flu virus. there was nothing secret in the images of pandemic viruses built by these microbiologists, unlike simulations of nuclear explosions built indoors by particle physicists (gusterson ) : all the phylogenetic trees produced by gavin and his team were publicly available on websites. drawing back the 'molecular clock' based on the estimated kinship relations between viruses, virologists could see the branches where evolutionary ruptures occur and pathogens jump from one species to another, such as the emergence of the h n pandemic in and . following continuities between genetic sequences, they exhibited the discontinuities between evolutionary niches. gavin said that when a virus jumps from one species to another, it inaugurates a new set of lines, as the 'immunity pressure' of the environment creates an 'evolutionary bottleneck' in which this mutation can replicate. drawing back these lines then lead him to what he named 'the most recent common ancestor' . 'i love those trees' , he added. the amount of information provided in a single image was correlated to the unity of an evolutionary hypothesis drawing this information back to a common ancestor. historians of science have shown the power of evolutionary trees in the books through which darwinism came to be accepted as a new worldview (bredekamp ; helmreich ), and their reframing in global health under the notion of an animal reservoir in which emerging pathogens spill over from animals to humans (king ; lynteris ) . but i was mostly intrigued by the way gavin and his team turned sequences into images through an anticipatory mode of reasoning that i call 'reverse scenario' . natasha schull proposes the term in her work with on-line gamblers, to describe the way they 'cope with the necessarily uncertain futures of any hand by returning them to a point in the past and confronting them with a branching diversity of outcomes that might have emerged from it' ( : ). it applies well to the practices of 'virus hunters' who use 'reverse engineering' to reconstruct potentially pandemic pathogens such as the h n virus (caduff : ; napier : ) . just as a gambler speculates how much he could have won if he had played this or that card, gavin imagines what could have happened if the h n virus had been detected in pigs prior to or . virus sequencing allows him to trace potential connections between birds, pigs, and humans, and to imagine other futures of cross-species transmission. yet we don't know how birds (and pigs) are actually involved in the construction of pandemic scenarios, because we don't see how virologists take virus samples from birds. we thus need to turn from desktop simulations to 'real-ground' exercises organized by public health officials and birdwatchers. after my visit to gavin smith at nus duke graduate medical school, i went to a nearby building to meet jeffery cutter at the singapore ministry of health. trained as an epidemiologist, jeffery cutter was the director of the communicable diseases division of the ministry of health, co-ordinating preparedness for emerging infectious diseases in singapore. 'there are million passengers every year at singapore changi airport' , he told me, 'so there is a high probability that emerging infectious diseases will come to singapore. we need to be prepared' . during the sars crisis in , he said, people were infected by the new coronavirus, with thirty-three deaths. they were all treated at the tan tock seng hospital, which had been designated by the government as an isolation hospital for sars patients. at the peak of the crisis, all schools in the country were closed for ten days, and home quarantine was established for more than , people known to have come into close contact with a sars-infected person. prime minister goh chok tong said publicly that sars could possibly become the worst crisis singapore had faced since independence. when a journalist asked him if he was being alarmist, goh responded: 'well, i think i'm being realistic because we do not quite know how this will develop. this is a global problem and we are at the early stage of the disease' (zolli ) . jeffery cutter introduced me to yoong cheong wong, head of the emergency preparedness & response division at the ministry of health. mr wong was a former policeman in charge of organizing exercises for emerging infectious diseases in hospitals. the first national exercise for influenza in singapore was organized in , after the first cases of human-to-human transmission of h n were suspected in thailand. called 'sparrowhawk' , it was organized in two stages: a table-top discussion and assessment of pandemic response plans among six hospitals in the country between april and june; and a practical exercise on - july, in which the six designated hospitals had to manage potential patients and share information about their circulation. mr wong explained that a thousand people were involved in the real-ground drill, mostly volunteers from grassroots organizations and nurses from training institutions. while patients moved from one hospital to another, some hospitals assessed the behaviour of others and gradually raised the number of casualties. the main question, according to mr wong, was: 'if there are casualties in one hospital, which resources do they need?' the goal of these exercises is officially the identification of unplanned gaps in coordination between the actors who manage epidemics. but the actual criticism of planners most often focuses on the drills' lack of realism. 'we try our best to do it as real as possible' , said mr wong, 'but everyone knew it was just an exercise' . to explain the improvement between 'sparrowhawk' exercises in and in singapore, an official leaflet notes, 'the exercises were activated unannounced to inject greater realism. the ministry of health emergency medical staff turned up without prior justification at the general ward of the exercise hospital and "triggered" the simulated case of human infection with avian influenza' (unsic : ) . realism, in this case, came from the fact that people were surprised, and yet they knew that they were faking the epidemic. what does it mean for a simulation to be realistic? here the notion of 'reverse scenario' is useful. just as microbiologists imagine what could have happened if viruses had been stopped in their animal reservoir, public health planners imagine what would happen if contagious patients were stopped before entering hospitals. but in both cases, death is not performed in the scenario. by contrast, another type of exercise conducted in singapore was very real. on july , the agriculture and veterinary authority (ava) organized a drill in one of the poultry slaughterhouses on the border with malaysia. there are no authorized poultry farms on the territory and only five chicken farms for eggs, which constrains singapore to import and slaughter million live chickens from malaysia every year. malaysian farmers need to be licensed by the ava to import their poultry to singapore, and are always regarded with suspicion by border authorities. and yet no case of h n has been found in singapore. i was able to watch the drill on-line because it was streamed widely on a number of websites. the name, 'exercise gallus vii' , referred to the fact that it was the seventh avian influenza exercise conducted by the ava since . it took place in the biggest of the ten slaughterhouses in singapore run by soonly food processing industry, which processed , chickens daily, providing per cent of the fresh chicken meat in singapore (asia one ). the scenario for the exercise was the following: , chickens had been infected with h n and should be killed and destroyed, according to emergency response plans. about employees of the slaughterhouse, mostly indians, had to be screened for their temperature, take an antiviral drug, and then wear personal protective equipment (boots, cap, mask, glasses, gloves) on the back of which their name was written. the 'affected' chickens were placed in green cages on belts, immersed in water, and electrocuted. their cadavers were then placed inside two layers of biohazard bags to be incinerated. dr yap him ho, director of the quarantine and inspection group, declared on television, 'to make sure that ava is prepared for any incursion, the main thing we want to do for this exercise is to train our officers, as well as the other parties that are involved in the contingency planning, to be familiar with the steps of the procedures' (straits times ). although much could be said on the paternalistic ethnic, gender, class, and age divides that structured these exercises, i want to focus on the distinction between humans and animals. while the simulation at the clinic was animated by a sense of urgency and scarcity of resources confronted with a fake pandemic, the simulation at the slaughterhouse was quietly following the procedures in actually killing false positive chickens. i was also intrigued by the fact that while the hong kong government organized many such exercises on the human side, they had never simulated bird flu in poultry farms, because outbreaks occurred regularly in farms on its territory. while singapore authorities actually killed poultry for a disease that remained virtual, hong kong authorities simulated the transmission of bird flu from chickens to humans because it was already circulating among birds. although avian influenza kills birds as well as humans, the reverse scenario of a pandemic represents massive death in a different mode for humans and for birds, depending on past experiences of pathogens crossing borders between species. i now turn to the simulation of bird flu in hong kong. on november , hong kong co-ordinated a desktop exercise called 'great wall' which simulated a virtual cluster of three human infections with h n in a family returning to hong kong and macau after their visit to a poultry market in mainland china. the goal of the exercise was 'to synchronize the three systems of pandemic preparedness to engender an effective response among them' (unsic : ) . the exercise opened with a ceremony attended by the vice-minister of the chinese ministry of health, wang longde. it was considered as a success in creating good relations between mainland china and the former british and portuguese colonies. while the sars coronavirus had caused a division between china and the former colonies in because of beijing's reluctance to share information (abraham ) , 'great wall' unified the country against an imagined enemy, pandemic avian influenza, but it instantiated ruptures between humans and birds. in january , after long discussions with the centre for health protection, i was allowed to participate in an exercise in a hong kong hospital. the centre for health protection was created by the department of health after the sars crisis to anticipate outbreaks similar to sars through active surveillance and communication (leung & bacon-shone ) . within this centre, the emergency response branch, headed by a police officer, was in charge of writing scenarios and organizing simulations. twice a year, a field exercise was held in hong kong, with observers from china and overseas, bearing the name of natural entities: maple, cypress, chestnut, redwood, eagle, jadeite, and so on. there was no epidemic simulation in hong kong in because the emergency response branch considered the management of the h n virus in the spring and autumn to be a 'real-life exercise' . 'exercise redwood' took place in the clinic of shau kei wan, located in the workingclass district of hong kong island. the following scenario was distributed to the participants and posted at major public buildings. confirmed human cases of bird flu had been reported in hong kong's neighbouring countries, as well as a rising trend in patient attendance with influenza-like illness in hong kong hospitals. live poultry had tested positive for avian influenza in hong kong's markets and were then culled at farms and markets. a member of the staff participating in the culling was reported to carry the h n virus, as was an -year-old boy who had played with live poultry. four clinics were designated in hong kong for triage. only the final part of the scenario was held in shau kei wan; the first part was meant to provide a plausible context. the official purpose of the simulation was to co-ordinate hospital services in the management of patients with influenza-like illness. eighty actors playing patients came in through the front door of the hospital and were sent to different departments depending on their symptoms (pulmonary conditions, tuberculosis, etc.). twenty 'players' treated them in the services, and two 'simulators' communicated with other hospitals on a hotline. those who were diagnosed with h n were evacuated by ambulance through the back door of the hospital, where the media took pictures. the head of the department of health gave a press conference after visiting the hospital, but the journalists asked him about new bacteria found in a private jacuzzi, not about the exercise itself. the drill's success was not questioned; it was successful because it had been held. the scenario was designed in such a way that no surprising event could happen: the only reality that came up was the bacteria in the jacuzzi, not the virus in bird markets. all the actors i saw looked young and relaxed, wearing blue caps and casual clothes. their symptoms were described on a tag they wore around their necks, indicating their name, address, nationality, sex, and age. these cards were red or green depending on whether they had bird flu or only influenza-like symptoms. they did not have to fake illness; their only role was to move to the designated departments. in another exercise organized by the centre for health protection, a plane was evacuated because a patient had been found with influenza-like symptoms; those who sat next to the patient received a red tag, and those who sat at a good distance received a yellow tag. what was remarkable in 'exercise redwood' was the absence of tension or anxiety in the medical staff's behaviour. although humanitarian ngos consider triage to be an ethical issue when a higher number of patients is met with limited resources (nguyen ; redfield ) , the medical staff of the shau kei wan clinic only separated symptomatic and asymptomatic patients to avoid the spread of the disease. the tension of the situationwho would be considered a spreader, who would receive treatment first -was delegated to objects: tags and caps. people were reduced to bearers of signs that circulated fluidly in the hospital under the gaze of the media. while the medical staff of the hospital played their own role, the actors playing patients with influenza-like illness came from a humanitarian association, the auxiliary medical service (ams). this association, created in to deal with the influx of chinese refugees, was registered in under the security department of the hong kong government. its , members are trained for disaster management in hong kong and outside. one of them described it to me as 'after-work entertainment' , 'a place to meet other singles'; it is an elite association where similar people express and share moral values. during their own exercises, performed every month, they train how to rescue victims of car accidents or fires. they simulate heartbeats on dummies with fake hearts. 'patients cannot fake the heart rate or the respiratory rhythm' , said the organizer, 'so they have tags' . tags have an indirect realistic effect, while dummies can actually simulate the heartbeat of an injured victim. members of the ams, who describe their own exercises as significant moments in the life of the association, were frustrated by 'exercise redwood' . from their perspective, there is a sharp difference between regular accident rescue exercises and extraordinary epidemic evacuation drills that co-ordinate several departments. one of the actors said he felt 'passive' , playing on the ambivalence of the term: as we had experienced sars in , we all can forecast how we would behave in another similar situation, like avian flu. being a citizen, we are quite passive; i believe that we should follow the guidelines and the government's advice so as to prevent ourselves from getting affected. but in the exercise, we were being passive. it can be said, consequently, that when they simulate patients in an epidemic exercise, members of the ams literally act as if they were dummies. there is thus a fundamental distinction in the real-ground exercises between actors and players. while actors are passive, reduced to the objects that 'act' or 'speak for them' , players and simulators introduce uncertainty by the way they combine these objects in the scenario. if actors have to appear 'real' to produce good images in the media, the simulators play on the fictional possibilities of the scenario. the distinction between simulators and actors in real-ground simulations runs parallel to the distinction between virologists and public health planners in desktop exercises: while actors and planners only follow their roles in the exercise, simulators and virologists explore the potentialities of reverse scenarios. another example shows how real-ground exercises combine the virtual and the actual as desktop simulation does. in an exercise called 'jadeite' , organized in january , members of the emergency response branch were simulating the evacuation of a residential building on computers, and the scenario specified that they had to evacuate the simulation room to a 'fallback room' . the simulation room, from which the vulnerability of vital infrastructures in hong kong was virtually assessed, thus came to be seen itself as a material environment under threat. the head of the emergency response branch who described this exercise to me said it was 'more fun than a movie' , as if images had suddenly burst through the screen. in this reversal of the scenario, simulators became actors, and fiction reality. neither a ritual performance nor a scientific model of prediction, the simulation was, for this former policeman, a game he enjoyed playing. animals take part in simulations in a general category that can be called 'passive actors' . if there was no need to simulate the culling of poultry because it regularly happened in hong kong markets, simulators for the evacuation of residential buildings in hong kong planned that some residents were accompanied by pets that should be handled with care by the agriculture department, because their reaction to the evacuation was unknown, just as simulators of the evacuation of planes planned how to handle 'reluctant potential patients' . the real opposition in simulations is thus not between humans and animals but between poultry, handled as commodities that can be destroyed, ordinary citizens and pets, considered as 'passive actors' that should be handled with care, and simulators, changing the rules of the game. more than sharp ontological distinctions between fiction and reality or between animals and humans, there is a virtual gradient of actors in the anticipation of massive death produced by simulation. the use of accessories and animals in simulations of disasters is indeed an essential part of their 'realism' . tracy davis has shown that people coming from the world of theatre were hired by cold war experts to implement scenarios of nuclear blast through the design of accessories. simulation designers were, therefore, less concerned with the participation of the public than with the realism of the objects. after an exercise organized in coventry in , prime minister winston churchill complained about the high degree of realism of the simulations, which he considered a waste of public money. 'who thought of the blood-stained old woman with the birdcage? i hope there is not going to be any more of this sort of thing at government expense' (quoted in davis : ) . women were the main targets of civil defence after the second world war, as they had been the targets of public health campaigns against microbes at the beginning of the twentieth century, because they were in charge of the household with children and pets. animals were portrayed as good accessories of nuclear blast simulations not only because they were good laboratory models (masco : ) , but also because they were part of a familiar landscape disrupted by an extraordinary event. the extraordinary context of the simulation thus provides the opportunity to display a series of apparent contradictions: people become objects; animals become people; actors turn out to be passive; fiction enters into reality. this capacity to displace oppositions in an extraordinary context through reverse scenarios brings simulations close to rituals. however, if simulations can be considered as rituals of public health administration, justifying the work of virus hunters who sound the alarm about future pandemics, it doesn't mean that there is a secret worldview shared by simulators (gusterson ) . rather, simulations display openly contradictions that public health administrations have to solve, often by the use of sacrifice in operations of culling (of infected poultry) or triage (of suspected patients). they create a tension between two techniques of power: those of biologists and simulators who follow viruses as they mutate between species, which i describe as cynegetic, and those of public health officials who have to protect some populations against others, which i call pastoral. to support this hypothesis, i will now turn to simulations organized by birdwatchers. can we say that birdwatchers take the perspectives of threatened wild birds as virologists take the perspective of poultry infected with flu viruses? how do humans in charge of the protection of animals cope with the oppositions we have seen in reverse scenarios of pandemics? birdwatchers have been involved in the surveillance of the avian reservoir of influenza viruses. public health and agriculture authorities realized that they could not follow the mutations of flu viruses in wild birds, and collaborated with birdwatching associations to monitor potential cases in wild bird reserves and natural environments. in hong kong and taiwan, birdwatching practices, a privilege of british and american expatriates until the s, have become popular among chinese middle classes with the development of a leisure society, the commercialization of camera equipment, and the awareness of the vulnerability of the environment (choy ) . birdwatching has taken the form of a 'citizen science' with the opening of websites where amateurs post their observations and experts turn them into statistical data. every year, bird races offer opportunities for birdwatchers to compete in observing the highest number of birds on a designated territory. thus, birdwatching practices, like simulations, have virtual and actual aspects, orientated by the imagination of a disaster: the extinction of bird species. in hong kong and taiwan, the introduction of birdwatching was linked to techniques of preparedness and concerns for biosecurity. the main wild bird reserve in hong kong, mai po, is situated on the estuary of the pearl river delta and on the border with mainland china. after , british officers used to sit there with their binoculars to trace chinese refugees or to signal an attack by the chinese army, and took this opportunity to inventory the more than bird species in hong kong. hong kong and taiwan were part of the migratory animal pathological survey, a programme of surveillance of pathogens carried by birds (particularly japanese encephalitis). through this programme, british and american ornithologists trained chinese workers to band birds and collect samples. transforming birds into data and following the evolution of their numbers has been a way to simulate threats coming from birds since the second world war (keck ) . methods derived from us wildlife management have changed the perception of birds in the last twenty years in taiwan and hong kong, with the introduction of the concept of the flyway. species that fly from japan and korea to australia, along what came to be called the east asian-australian flyway, have been shown to have declined owing to the urbanization and development of the chinese coast. climate change is also supposed to damage the places where wild birds feed and roost on their migratory routes. among the bird species affected by these changes, one of the most charismatic is the black-faced spoonbill, a waterbird breeding in japan and korea in the summer and migrating to south china in the winter. in the s, the number of these birds was estimated to be , , but thanks to the conservation efforts shared by the countries to which they migrate, it increased to , at the end of the s. wetlands have been developed in hong kong, taiwan, and fujian as shelters on their flyways. images of spoonbills abound in schools, environmental agencies, and natural reserves, often portrayed as funny birds smiling to the public. to understand how reverse scenarios of disasters enter the management of spoonbills in china, we have to go beyond these anthropomorphic images, and look at how they actually perform in simulations. in the winter of - , seventy-three black-faced spoonbills were found dead from botulism in taijiang national park. the wild bird society of tainan consequently organized a campaign to vaccinate spoonbills against botulism, and used decoys to train their staff on how to safely handle the birds. since then, drills have been regularly organized for bird protectors to learn how to manipulate fake spoonbills with caution. these decoys are also used to attract spoonbills for gps monitoring. carved in wood and painted in black and white, they are posted in the wetlands close to traps. decoys are different from images of spoonbills on posters: wildlife managers interact with them as if they were alive, because of their accurate mimicking. the use of decoys is a traditional feature of bird hunting. by contrast with lures, which attract birds based on their appetites, decoys attribute intentions to prey (schaeffer : ) . in england, duck decoys take the form of pondside wooden houses into which ducks are attracted by a fake dog, because hunters have observed that ducks swim towards the dog to signal that it has been seen. in the same way, the fake spoonbill is used as a decoy because it creates a situation of communication with the bird. but at the same time, the fake spoonbill is used as a dummy by birders who train to manipulate spoonbills in risky situations, as in epidemic simulations. the use of spoonbill decoys mixes hunting techniques and pastoral techniques because decoys are considered both as intentional agents and as objects that should be manipulated with care. this hypothesis was confirmed on april when the wild bird federation of tainan led me to a site where three black-faced spoonbills had been trapped -a very rare event, which i was considered lucky to have witnessed. birdwatchers had found shelter in a taoist temple on the banks of the marshes, and they turned on some buddhist music to soothe the birds. with very calm gestures, a man equipped with gloves and a mask sewed a gps satellite tracking device around the waist of the spoonbill, while a woman held it gently but firmly. five other birdwatchers watched them with amusement, taking pictures and making comments on the bird's reactions. the man explained to me that he had to be cautious because it was a young spoonbill, so the weight of the satellite tracking device had to be imposed on its body in such a way that it would not hamper its growth or unbalance its flight. how to build techniques of monitoring that do not kill animals considered as indexes of the fate of their species is a major concern for wildlife managers, who often talk about the sacrifice of individual animals when they die as the result of an improper monitoring device (benson ) . but taiwanese birdwatchers focused the discussion on how to properly release these birds so that they would not be sacrificed but become sentinels of a threatened species. the release of birds is a major ritual concern in south china, known as fangsheng (literally 'let live'). this practice finds its roots in aristocratic practices of opening the cages of birds who sang well, and was codified in taoist rituals as a specific sequence of releasing a live animal; but it has developed massively in recent centuries with its qualification by buddhists as a practice of compassion that increases the 'merits' (gongde) of those who release live animals (handlin smith ) . in hong kong and taiwan, buddhist associations entered into discussion with birdwatching societies because many birds were found dead after they were bought in bird markets and released in surrounding natural parks. these associations had to warn through posters that releasing birds could cause the death of birds, because they were released in an improper environment, and the death of humans, since some of the birds found dead after the release carried avian flu (severinghaus & chi ) . consequently, when they released a bird equipped with gps that they had learned to manipulate through the use of decoys, taiwanese birdwatchers inserted a ritual sequence into a simulation practice. while the ritual introduced the bird into a cycle of life and death, the simulation used the decoy to produce signs of future threats for birds and humans. the black-faced spoonbills were released in the taijiang national park with the hope that they would fly over to hong kong or the fujian coast, where their signals could be captured. it should be noted that the taiwan straits are also the sites of military exercises or drills through which threats coming from china are mitigated. to prepare for an attack from the people's republic of china, the taiwanese centers for disease control was organizing exercises simulating the use of bioweapons in a public space, such as sars, smallpox, and avian flu virus (rollet : ) . the release of a black-faced spoonbill in the same chinese straits mimics and reverses the scenario of an avian flu outbreak from china. instead of carrying information on the potential war between two long-term enemies, it produces signals on the changes of bird habitats that concern birds as well as humans. while in the public health simulations birds are considered as carriers of infectious diseases, birdwatchers' simulations frame them as living beings with which humans share pathogens as signs of communication. another practice with birds in taiwan clarifies by contrast their role in simulations. according to peta, more than a million pigeons are released every day from boats in the taiwan straits by pigeon-racing clubs, and only per cent survive to come back to their shelter. huge amounts of money (an estimated us$ billion) are spent in bets on those which will return, welcomed as heroes if they are first, killed if they are too slow. this is neither a ritual nor a simulation but a gambling practice through which birds crossing the sea between china and taiwan are qualified as political signifiers. the reverse scenario of the game, producing strange identifications between humans and birds, tells the story of a pigeon successfully returning home while others fail and die in the taiwan straits. releasing a bird in taiwan can thus appear as a simulation when it is embedded in the framework of an environmental flyway, as a ritual when it mobilizes a cosmological view of the circulation of souls between humans and animals, or as a game when it is organized on the border separating two competing territories. simulation, ritual, and play are three frameworks to mitigate the uncertainties of catching and releasing a potentially sick bird. i have considered three stages where bird diseases are simulated: computer simulations of avian influenza by microbiologists; outdoor performances of pandemic influenza by public health administrations; and exercises of manipulating threatened birds by birdwatchers. these three types of simulation displace the problem of sacrifice: that is, the definition of those who deserve to live and those who will die. microbiological surveillance of viruses moves away from the site of emergence where birds are killed to prevent the spread of pathogens to humans, and traces continuities between humans and animals as a reservoir where viruses silently mutate. simulations of epidemics don't address the problem of triage between humans in a situation of exception, but rather configure new relations between humans and animals through accessories in a performance. exercises of vaccinating and releasing potentially sick birds don't raise the issue of how many birds can die for the sake of the species, but rather reflect on how to handle a bird with care in a political environment where they carry signals of threat. in the reverse scenarios of simulations, birds appear not as sources of infection that must be eradicated, but as sentinels with which humans can communicate to imagine potential futures. simulations, therefore, should be analysed not only as a pastoral technique of power, as ways to mobilize populations under a common threat in which some are sacrificed for the sake of others, but also as a cynegetic technique of power, creating relations of identification between humans and animals around a perceived uncertainty at the borders between species. in the world of databased science and transparency of communication, simulations of bird diseases imply playing like animals or with animals to anticipate the (im)possibility of a mass extinction, thus mobilizing elementary forms of identification. in the cases i have considered, the question of the realism of exercises is a way to draw attention to the circulation of objects that recast relations between humans and birds by simulating the diseases they share. the use of computer software, accessories, and decoys in the three types of simulations i have analysed blurs the sharp opposition between humans and nonhumans. these objects can be considered as decoys because they carry the intentions that humans attribute to animals and shift their perception from inanimate objects to living beings. while scenarios of bird-generated epidemics play on the asymmetries between humans and birds, the horizon of the simulation (the extinction of the human or of a bird species) integrates them as common actors of a game. simulations can thus be considered as reflexive rituals because they display the uncertainties of the beings they play with and help to mitigate their threats. framing simulation as an operation unfolding between the spheres of mimetic play and reflexive ritual, and at the same time performing a series of subject-object reversals, i have argued for the need to approach this key apparatus of preparedness through a lens that allows for the mixing of pastoral and cynegetic techniques. what i have called in this article 'avian preparedness' takes place in a long history of simulating bird movements, from classical divination by roman augurs to medieval bird hunting and modern birdwatching. the specificity of contemporary forms of anticipation through sentinels, simulation, or stockpiling is that the distinction between cynegetic techniques of preparedness, taking the perspectives of birds on future threats through imagination and communication, and pastoral techniques of prevention, protecting human or nonhuman populations from external dangers through risk calculation, has become more difficult to make and yet more urgent. this article has argued for such a distinction, while opening the stage for future analyses of simulations as forms of play and ritual. this research was made possible by a project on simulations of disasters headed by sandrine revet at sciences po paris in - . i am grateful to her and to marc elie and guillaume lachenal for the discussions we had on simulations, as well as to the four anonymous reviewers and the editors of the jrai, who helped me improve the writing of this article. this approach was launched in by the wildlife conservation society, and then endorsed by the international organizations for human and animal health (http://www.oneworldonehealth.org/, accessed february ). contrary to other viruses such as smallpox, flu viruses don't have their genetic information encoded in dna (a double-stranded helix of nucleic acid) but in rna (a single-stranded ribonucleic acid). this explains why they mutate more randomly. anonymous interview by email after a questionnaire sent to the ams, february . http://www.peta.org/action/action-alerts/first-ever-taiwan-raid-police-bust-pigeon-racers/ (accessed february ). twenty-first century plague: the story of sars anticipation: technoscience, life, affect, temporality rehearsing for the plague: citizens, security, and simulation ava holds culling exercise in poultry slaughterhouse wired wilderness: technologies of tracking and the making of modern wildlife darwins korallen: frühe evolutionsmodelle und die tradition der naturgeschichte material proximities and hotspots: towards an anthropology of viral hemorrhagic fevers the pandemic perhaps: dramatic events in a public culture of danger manhunts: a philosophical history ecologies of comparison: an ethnography of endangerment in hong kong stages of emergency: cold war nuclear civil defense wild goose chase: the displacement of influenza research in the fields of poyang lake, china omnes et singulatim: towards a criticism of political reason image and logic: a material culture of microphysics nuclear rites: a weapons laboratory at the end of the cold war chicago: hau books. handlin smith, j.f. . liberating animals in ming-qing china: buddhist inspiration and elite imagination alien ocean: anthropological voyages in microbial seas more than one world, more than one health: re-configuring interspecies health dissimulation and simulation as modes of religious reflexivity une sentinelle sanitaire aux frontières du vivant: les experts de la grippe aviaireà hong kong security, disease, commerce: ideologies of postcolonial global health how forests think: toward an anthropology beyond the human preparing for the next emergency hong kong's health system: reflections, perspectives and visions containment and competition: transgenic animals in the one health agenda viral clouds: becoming h n in indonesia zoonotic diagrams: mastering and unsettling human-animal relations bringing sequences to life: how bioinformatics corporealizes sequence data viral network: a pathography of the h n influenza pandemic the nuclear borderlands: the manhattan project in post-cold war new mexico infectious change: reinventing chinese public health after an epidemic the age of immunology: conceiving a future in an alienating world the republic of therapy: triage and sovereignty in west africa's time of aids fungible life: experiment in the asian city of life un ethnologue chez les chasseurs de virus: enquête en guyane française a small world': ethnography of a natural disaster simulation in lima dimensions identitaire, sécuritaire et sociétale de la politiqueétrangère de taiwan dans le domaine de la lutte contre les maladies infectieuses the human is more than human: interspecies communities and the new 'facts of life'. cultural anthropology website pourquoi la fiction? paris: seuil the gaming of chance: online poker software and the potentialization of uncertainty ritual and its consequences: an essay on the limits of sincerity prayer animal release in taiwan an influenza epicentre? models, simulations and their objects dating the emergence of pandemic influenza viruses emergence and predominance of an h n influenza variant in china origins and evolutionary genomics of the swine-origin h n influenza a epidemic culling exercise. razor tv simulation exercises on influenza pandemic responses in the asia-pacific region flight ways: life and loss at the edge of extinction seeking refuge: birds and landscapes of the pacific flyway learning from sars. andrewzolli.com cet article décrit les relations entre humains, animaux, artefacts et pathogènes dans les simulations de désastres, en considérant les maladies qui affectent les oiseaux dans trois territoires sentinelles aux frontières de la chine comme des cas ethnographiques. en s'appuyant sur les distinctions entre la simulation, le ritual et le jeu, il montre que l'engagement des acteurs dans l'imaginaire des simulations, qu'ils décrivent sous le terme de « réalisme », renverse réflexivement les oppositions entre les humains and les non-humains, l'actif et le passif, la fiction et la réalité qui organisent la vie quotidienne. en empruntant les concepts de l'anthropologie des sociétés de chasseurs, il montre que les simulations de maladies aviaires, lorsqu'elles sont perçues comme des signes d'une potentielle extinction d'espèce, recourentà des techniques de pouvoir cynégétiques, dans lesquelles des humains et des animauxéchangent symétriquement leurs perspectives, et pas seulementà des techniques pastoralistes, dans lesquelles les humains sont au-dessus de la population qu'ils surveillent et parfois sacrifient.frédéric keck is a researcher at the laboratoire d'anthropologie sociale (collège de france, ehess, cnrs, psl). he has conducted research on the history of social anthropology and on the contemporary management of animal diseases, and headed the research department of the musée du quai branly.laboratoire d 'anthropologie sociale, rue cardinal lemoine, paris, key: cord- - c gch b authors: to, kelvin kw; chan, jasper fw; chen, honglin; li, lanjuan; yuen, kwok-yung title: the emergence of influenza a h n in human beings years after influenza a h n : a tale of two cities date: - - journal: lancet infect dis doi: . /s - ( ) - sha: doc_id: cord_uid: c gch b infection with either influenza a h n virus in or avian influenza a h n virus in caused severe pneumonia that did not respond to typical or atypical antimicrobial treatment, and resulted in high mortality. both viruses are reassortants with internal genes derived from avian influenza a h n viruses that circulate in asian poultry. both viruses have genetic markers of mammalian adaptation in their haemagglutinin and polymerase pb subunits, which enhanced binding to human-type receptors and improved replication in mammals, respectively. hong kong (affected by h n in ) and shanghai (affected by h n in ) are two rapidly flourishing cosmopolitan megacities that were increasing in human population and poultry consumption before the outbreaks. both cities are located along the avian migratory route at the pearl river delta and yangtze river delta. whether the widespread use of the h n vaccine in east asia—with suboptimum biosecurity measures in live poultry markets and farms—predisposed to the emergence of h n or other virus subtypes needs further investigation. why h n seems to be more readily transmitted from poultry to people than h n is still unclear. the infl uenza viruses belong to the rna virus family orthomyxoviridae. on the basis of antigenic and genetic diff erences between the internal proteins, nucleoprotein and matrix protein, infl uenza viruses are classifi ed into a, b, and c. the infl uenza a virus has a negative-sense, single-stranded, and eight-segmented genome. on the basis of two surface proteins, haemagglutinin subtypes and ten neuraminidase subtypes can be found (fi gure ). except h and n , which have been found in bats only, all haemagglutinin and neuraminidase subtypes have been found in wild waterfowl. unlike other neuraminidase subtypes, n does not have neuraminidase activity. the haemagglutinin subtypes are further classifi ed into group and group on the basis of the antigenic and phylogenetic characteristics of haem agglutinin. the ha subunit of the haemagglutinin attaches onto host cell sialic acid receptor. the haemagglutinin precursor protein ha is cleaved by proteases into ha and ha before ha can mediate virion-cell fusion. the internal proteins are encoded by six other gene segments encoding nucleoprotein np, matrix protein m , ion channel protein m , the polymerase complex proteins pb , pb , pa, including pb -f , pa-x, pa-n , pa-n , and non-structural proteins including pb -f , pa-x, pa-n , pa-n , ns , and ns . , the eight gene segments can reassort when two diff erent viruses infect an animal host cell. phylogenetic analysis shows that the h n virus infecting human beings was a reassortant with goose h n haemagglutinin, teal h n neuraminidase, and internal genes from quail h n and teal h n . , the h n virus that infected human beings in the netherlands was a reassortant between avian infl uenza a h n , infl uenza a h n , and other eurasian avian infl uenza viruses (fi gure ). on the basis of available sequences in the public domain, the h n virus is also a reassortant of avian infl uenza viruses consisting of haemagglutinin and neuraminidase most closely related to h n viruses isolated from ducks in zhejiang and h n viruses from wild birds in korea, respectively. the m, np, and ns genes are most closely related to h n viruses from chickens in eastern china, whereas personal view the pa, pb , and pb genes are most closely related to those of h n viruses from brambling in beijing. , , , , because the origin of all gene segments of the h n virus are avian, gene reassortment probably took place in an avian host. although reassortment events of avian infl uenza viruses have been recorded in pigs in korea, the h n virus and the immediate precursors have not been found in pigs. the haemagglutinin sequence of one of the h n virus human isolates (a/shanghai/ / ) was phylogenetically distinct from other human and avian isolates, , suggesting that this new reassortant might have been circulating for some time to achieve this degree of diversity. because of the roughly % nucleotide diff erences in the h and n genes between the h n virus and the closest avian virus genes, more extensive virological surveillance of wild or domestic avian and non-avian animal species, as has been done for the severe acute respiratory syndrome coronavirus, is needed to understand the evolutionary pathway of this h n virus, which is the fi rst n subtype virus infecting human beings. up to now, only one wild pigeon from nanjing has tested positive for the h n virus, but the epidemiological and genomic details of this virus isolate are not yet available. one unique feature of the h n human epidemic is the absence of preceding die-off s in poultry or wild birds, which makes epidemiological control diffi cult. the start of the h n outbreak in was marked by three highly pathogenic avian infl uenza virus outbreaks on farms month before the fi rst human case and about avian infl uenza virus can be divided into highly pathogenic avian infl uenza virus and low pathogenic avian infl uenza virus on the basis of pathogenicity in chickens. the world organization for animal health has defi ned highly pathogenic avian infl uenza virus as any infl uenza virus that is lethal for six or more of eight - -week-old susceptible chickens by days after intravenous inoculation with · ml of a / dilution of a bacteriafree infective allantoic fl uid, or that has an intravenous pathogenicity index of greater than · , which is calculated by scores on the severity of illness. one key feature of highly pathogenic avian infl uenza virus is the presence of multibasic aminoacids at the haemagglutinin cleavage site, which render haemagglutinin susceptible to cleavage by many diff erent proteases. hence, h or h viruses that have low pathogenicity in chickens are still regarded as highly pathogenic avian infl uenza virus if their ha cleavage sequence is similar to that of other highly pathogenic avian infl uenza viruses. the haemagglutinin cleavage site from all reported h n viruses do not possess multibasic aminoacids. , , data from preliminary pathogenicity testing suggest that chickens and quails infected with h n do not show signs of illness. a low pathogenic avian infl uenza virus can mutate to become highly pathogenic during an outbreak in domestic poultry. for the h n virus outbreaks in and , the diff erence in the cleavage site between low pathogenic avian infl uenza virus and highly pathogenic avian infl uenza virus was speculated to be a sequence insertion from the neuraminidase or m gene at the haemagglutinin cleavage site through intersegmental recombination. close monitoring of the evolution of the h n is needed. another possible explanation for the apparent absence of a preceding infection with h n in poultry in the outbreak is that previous infection by a closely related low pathogenic avian infl uenza h virus elicited crossprotection for this h n virus because h n virus was recently reported in ducks in zhejiang, china. furthermore, prevalent h n infections in poultry or the extensive use of the h n vaccine in poultry in china might induce cell-mediated immunity against highly conserved internal viral proteins without inducing any neutralising antibody. this process might be suffi cient to militate against poultry death, but not asymptomatic viral shedding. the eff ect of previous infection by other avian infl uenza virus subtypes and previous h n vaccine on the susceptibility to infection by h n deserves further investigation. interspecies jumping of an avian infl uenza virus into human beings is favoured by several factors: viral mutations that allow the virus to bind, replicate, and spread in human beings; a high inoculum of virus during the transmission between the poultry and human being; host susceptibility such as the presence of underlying diseases; extremes of age; and genetic predispositions. one key viral factor governing host adaptation and transmission is the relative binding affi nity between haemagglutinin and the sialic acid receptor on the host cell surface. avian infl uenza viruses generally prefer α- , sialic acid receptors abundantly found in avian alimentary tract and human infl uenza viruses generally prefer α- , sialic acid receptors abundantly found in the human respiratory tract. h n viruses can invade the lower respiratory tract of human beings because the viruses retain strong affi nity for the α- , -linked receptors present in the lower respiratory tract of human beings. an increased affi nity for the α- , -linked receptors, which are abundant in the upper respiratory tract of human beings, is believed to be responsible for transmission between birds and human beings. in egypt, which has had the highest number of h n infections since , % of virus isolates had a thr ala (h numbering) mutation, which is associated with loss of glycosylation at position - , and increased transmissibility in ferrets and guinea pigs. , thr ala was also present in all reported strains of h n (table ). the haemagglutinin mutations gly val and gln leu, which increase the binding of h n and h viruses to α- , -linked receptor and h n virus transmission between ferrets, are present in most strains of the human and avian h n , but none of the h n strains (table ). , , , - however, a recent structural modelling and binding study with human tracheal epithelium and alveolar tissue sections suggested that h n has weak binding to both α- , -linked and α- , -linked receptors. further studies should confi rm whether various strains of h n diff er in binding affi nities. neuraminidase enables release of virus particles from the host cell surface. deletion in the stalk region of neuraminidase, which was found in the human h n viruses and previous h viruses, is associated with increased virulence and replication in the respiratory tracts of chickens. h n also has a fi ve aminoacid deletion in the stalk region, which might improve its adaptation to poultry. , , , comparative studies in wild waterfowl and domestic chickens will ascertain the degree of adaptation by this virus in these avian species. mutations in the polymerase complex aff ect viral replication. pb glu lys mutation is associated with increased viral replication at °c, the nasal body temperature in human beings, which is markedly lower than that of avian species. furthermore, this mutation is important in aerosol transmission of avian h n virus between ferrets. glu lys was found only in human strains, but not the avian strains, of h n or h n (table ) . however, glu lys was specifi cally found in the qinghai outbreak of h n in . pb asp asn is another important mutation associated with mammalian adaptation and transmission. , notably, most virus isolates from individuals infected with h n had either glu lys or asp asn, but not both. asp asn can compensate for the lack of glu lys for transmission between guinea pigs. other mutations aff ect viral replication, transmission, and virulence of infl uenza viruses. ns protein is the key virulence factor counteracting innate host immunity. ns protein contains a four-aminoacid motif at the c terminal that disrupts cellular signalling by binding to the host pdz domain-containing proteins. recombinant infl uenza virus with pdz-binding motif has increased pathogenicity in mice. ns protein from human seasonal infl uenza viruses cannot bind to human proteins containing pdz domain. the ns of all h n strains has a deletion of the pdz motif. the structural m protein is needed for viral assembly and budding. two mutations in m , asn asp and thr ala, associated with increased virulence in a mice model, are found in all strains of the h n virus. before the outbreak, the h n virus had never been reported to cause human infection, although other h viruses had been associated with sporadic infections since (table ) . , , , [ ] [ ] [ ] [ ] [ ] [ ] [ ] serological evidence of h infection was present in % of a rural population in the jiangsu province near shanghai. however, a study including serum samples from poultry workers in eastern china in did not identify any seropositive samples by microneutralisation assay, suggesting that subclinical h n infection was unlikely before . infl uenza a subtypes h n , h n , h n , h n , and h n were previously isolated from poultry and wild birds from china. , although studies of seroprevalence did not fi nd any evidence of h infection among sparrows or pigs in china, , h n viruses were isolated from birds in nearby countries, including mongolia and south korea in . , moreover, in the usa, h n viruses have caused outbreaks in chickens. other h n viruses were reported in wild birds or poultry from four continents. most of the laboratory-confi rmed cases of h n were older adults living in the city, with a median age of years. by contrast, in the h n outbreak in hong kong, % of patients were younger than years of age , and the mean age of patients with h n in china between and was · years (table ) . the severe disease in older adults and the small number of cases in children in the h n outbreak can be accounted for by several factors. first, h n infection in children was mainly mild or asymptomatic (appendix); , , therefore, infection in this age group might have been underdiagnosed because confi rmatory laboratory tests were usually reserved for severe cases. two children were found to be infected with h n during an enhanced surveillance that included children younger than years of age with infl uenza-like illness. second, some adult patients were poultry workers; generally only adults go to live poultry markets and therefore adults might have had a greater dose or prolonged duration of exposure to h n than did children. additionally, adults might have an increased chance of exposure to pet birds. finally, older adults might have impaired development of specifi c immune response to the h n virus because of the immunological phenomenon of original antigenic sin. previous exposure to other infl uenza viruses might also lead to rapid increase in non-neutralising antibodies against these viruses, which can be associated with more severe h n disease. , notably, most fatal or severe cases of h n have comorbidities, and up to a quarter of adult patients were smokers. the eff ect of genetic predisposition (eg, the ifitm and cd polymorphisms) on h n infection warrants further investigation. , a higher percentage of elderly patients aged years or older and a higher proportion of males were infected during the h n than were in the h n outbreak. one explanation for this fi nding could be that most grandmothers in shanghai take care of their grandchildren at home while the retired grandfathers go to live poultry markets for grocery shopping every day. another unique feature is that no poultry workers were infected with h n in the hong kong epidemic. seroepidemiology might ascertain the cause of this diff erence. human beings probably acquired the h n virus via direct contact with infected poultry or their surroundings, although aerosol transmission between ferrets was reported. ser variant associated with adaptation to pigs / all all all increased binding to α- , -linked sialic acid receptor all all of of gly val increased binding to α- , -linked sialic acid receptor of all nd nd increased binding to α- , -linked sialic acid receptor of * of nd nd cleavage by ubiquitous proteases nd nd all all deletions in stalk region increased virulence all all all all neuraminidase resistance of nd nd nd enhanced polymerase activity all all all all improved viral replication at °c of nd of nd mammalian adaptation of nd nd nd enables droplet transmission in ferrets nd nd nd nd enables droplet transmission in ferrets of all nd nd full-length full-length pb -f needed for virulence in mice all of all all increased virulence in a mice model nd nd nd nd asn asp, thr ala increased virulence in a mice model all all all all amantadine resistance all all nd nd increased virulence in mice all all all all pdz-binding motif signalling of host proteins deleted deleted avian type avian type personal view that % of transmission between farms was related to wind. up to may , , animal and environmental samples had been tested. samples were positive for the h n virus; of these were collected from poultry or environmental samples in poultry markets, one sample was collected from a wild pigeon in nanjing, and one sample was collected from a domestic racing pigeon at a household farm in nantong. h n viruses with very similar gene sequences have been found in pigeons, chickens, ducks, and environmental samples from poultry markets in aff ected areas. , , , as in the h n outbreak in hong kong, most confi rmed cases of h n ( · %) had history of contact with poultry. although some patients had contact with pigs, h n has not been isolated from pigs. , in the outbreak, the h n virus might have originated from poultry farms and was amplifi ed in overcrowded live poultry markets before its transmission to human beings. slaughtering and preparation of infected poultry constitute the highest risks of exposure to infected poultry secretions and excreta. although transmission to human beings through contact with wild birds or consumption of inadequately cooked poultry is possible, documentation of such occurrences is scarce even though h viruses are able to survive and remain infective for a prolonged period. no defi nitive evidence of continuing person-to-person transmission exists, although some fi rst-generation transmission might have occurred in four case clusters of which three were familial clusters. , however, exposure to a common avian or environmental source could not be excluded in these clusters. few reports of person-to-person trans mission of h n have been recorded. the predilection of the h n virus for the lower respiratory tract-shown by the higher virus burden in patients sputum than throat swab-might explain the low number of person-to-person transmissions as in the case of h n . reported h n infections in patients from march to may has far exceeded the reported h n infections in china within the past years. the crude case fatality of h n infection is %, which is lower than that for h n infection ( %), but much higher than the · % of the pandemic or seasonal infl uenza. , the true case fatality rate is uncertain because many of the patients are still receiving care in the intensive care units. enhanced surveillance between march and april , , in which patients with infl uenza-like illness were tested, identifi ed only two patients with h n who were not hospitalised. the fi rst human cases of h n were detected in shanghai, which is served by the farming and industrial establishments along the yangtze river delta. shanghai, a cosmopolitan megacity hardest hit by this novel virus, is similar to hong kong, a region that is served by the pearl river delta and where the fi rst human cases of h n were detected in . , , both cities have well established health-care infrastructure with the necessary diagnostic methods for the detection and charac terisation of new viruses. furthermore, both cities are located along the asian-australasian fl yway, where migratory birds stop at their wetlands and have surrounding poultry farms serving the densely populated areas that have many live poultry markets (table ) . between and , consumption of poultry per person has increased · times from · kg to · kg in urban areas, whereas overall consumption of poultry increased · times from · to · million tonnes in china between and . [ ] [ ] [ ] additionally, of all municipal areas or provinces in china, shanghai has the highest densities of both people and poultry. this is similar to the situation in hong kong, where poultry consumption increased greatly before the h n outbreak (fi gure ). , , the emergence of the h n virus in might also be related to the selective pressure induced by the widespread use of the h n vaccine because h and h are the common subtypes that generally cause poultry outbreaks. china uses more than % of the h n vaccine worldwide. netherlands human infections with one fatality; an outbreak in chicken arose before the human cases in the h n and h n outbreaks, infected individuals presented with acute severe community-acquired pneumonia that did not respond to typical and atypical antimicrobial coverage. in an analysis of of reported cases of human h n infections in , more than % of patients had fever or cough, and % of the patients had haemoptysis. % of the patients had acute respiratory distress syndrome. other complications associated with h n infection are rhabdomyolysis, acute kidney injury, encephalopathy, and multiorgan dysfunction. , unlike the h n outbreak, in which nearly % of patients had only fever and upper respiratory tract symptoms, none of the patients with h n infection had sore throat, rhinorrhoea, or conjunctivitis, although mild rhinorrhoea was reported in a · -year-old boy. gastrointestinal symptoms ( · %) were less common in people infected with h n than in those with the h n infection ( %). , reye's syndrome was reported in a child with h n infection. gastro intestinal haemorrhage, reactive haemo phagocytosis, and haemorrhagic pleural eff usion, which were present in some cases of h n , have not been reported for h n infection. coinfection at presentation or during admission to hospital can occur, as reported for h n . , , laboratory abnormalities in patients with either infections were prominent lymphopenia, thrombocytopenia, coagulo pathy, and raised serum transaminase, creatine kinase, and c-reactive protein concentrations. radio logical features were similar in both infections: pulmonary consolidation (which progressed to involve bilateral lung fi elds), diff use ground glass opacities, pleural eff usions, and mediastinal emphysema. none of these clinical, laboratory, and radiological manifestations are pathognomonic for h n infections. the defi nitive diagnosis depends on viral culture or real-time-pcr (rt-pcr) for the h and n gene targets from respiratory tract secretions. because of the predilection of this virus for the lower respiratory tract, if available, sputum, endotracheal aspirate or bronchoalveolar lavage might give a better sensitivity than throat or nasopharyngeal specimens. however, point-of-care rapid antigen tests and multiplex rt-pcr assays have low sensitivity. acute and convalescent serum antibody testing by haemagglutination inhibition or neutralisation can be useful for epidemiology or retrospective diagnosis. any febrile patients with history of travel to aff ected areas, or contact with poultry or infected patients can be tested for h n as a screening strategy for the early identifi cation of imported cases. h n is probably resistant to adamantanes because of the presence of an m ser asn mutation (table ). both genetic analysis and in-vitro testing showed that most strains of h n are susceptible to neuraminidase inhibitors. however, two reported strains carry the neuraminidase arg lys (n numbering) mutation, which is associated with resistance to oseltamivir and zanamivir (increase in half maximal inhibitory concentration [ic ] more than -fold for oseltamivir and between four-fold and -fold for zanamivir). personal view therapy of more than days after symptom onset was not an independent risk factor for acute respiratory distress syndrome in h n infections, previous experience from h n , pandemic, and seasonal infl uenza infections suggest that early oseltamivir treatment started less than days after symptom onset can reduce morbidity and mortality. , inhalational neuraminidase inhibitors such as zanamivir and laninamivir are unlikely to be helpful in patients with respiratory failure. , because oseltamivir might not aff ect outcomes in patients with late and severe infl uenza pneumonia, intravenous zanamivir and peramivir should also be investigated in future treatment trials. other investigational antivirals include those acting on the haemagglutinin receptor (das ), nucleoprotein (nucleozin), poly merase (viramidine and t ), and protease (aprotinin). antivirals targeting the host machinery including nitazoxanide were also reported. [ ] [ ] [ ] although h n is susceptible to neuraminidase inhibitors, the virus might develop resistance during treatment. mice infected with the infl uenza virus resistant to amantadine had improved survival when treated with the triple combination of amantadine, oseltamivir, and ribavirin. empirical antibiotics are initially needed to cover other common pathogens, such as streptococcus pneumoniae and staphylococcus aureus, but should be stopped when bacterial tests are negative. the role of immunomodulation remains controversial. glucocorticoids have been used in many patients with h n , but the benefi t is unclear. , non-steroidal anti-infl ammatory drugs such as celecoxib improved survival of mice with h n infection. confl icting outcomes of patients treated with statins and macrolides have been reported. the plasma of convalescent patients, which contains specifi c neutralising antibodies, has been used in patients with the h n virus, pandemic h n , and the pandemic h n . hyperimmune globulin was also used in the pandemic. both treatments have reduced morbidity and mortality in small studies. [ ] [ ] [ ] [ ] supportive measures in intensive care are especially important for patients with respiratory or multiorgan failure. extracorporeal membrane oxygenation could be benefi cial in patients with respiratory failure despite maximum mechanical ventilatory support. in view of the many similarities between the hong kong and shanghai outbreaks, many of the measures implemented in hong kong can be, and have already been, applied to the current outbreak in eastern china. in the hong kong outbreak, temporary closure of live poultry markets and cessation of poultry trading were instituted. subsequently, diff erent poultry species were segregated to reduce the risk of further genetic shanghai (registered population) hong kong year reassortment. the regular cleansing of designated transport cages in live poultry markets was introduced to stop the virus traffi cking between farms and markets. to interrupt the amplifi cation of infl uenza virus, a monthly rest day with no live poultry allowed in the wet market was implemented in hong kong in july . the isolation rate of h n from poultry in live markets before the rest day could be as high as %, but reduced to less than % after the rest day. to further reduce the spread of infl uenza virus in wet markets, overnight poultry storage was banned in july . a further % reduction in the isolation rate of h n was reported. as in the h n outbreak, poultry vaccination specifi cally against the h n virus could probably reduce its transmission. a mathematical model showed that poultry vaccination with a matched h n vaccine with coverage of only % of the poultry reduces the basic reproductive number to less than one. the h n human outbreak was stopped after a cull of all poultry in hong kong. subsequently, only registered farms with stringent biosecurity measures in china can import chickens to hong kong. if a highly pathogenic avian infl uenza virus outbreak arose, all live poultry and poultry products from the aff ected province would be suspended for up to days. for unaff ected farms within km of the index farm aff ected by the highly pathogenic avian infl uenza virus, there would be a day suspension for live poultry and poultry products. for farms where h n is detected by virological testing, similar depopulation and perimetric moratorium strategies of poultry control are necessary to control the source. the general public was educated to avoid contact with birds or poultry, to cook poultry thoroughly, and to comply with hand hygiene because consumption of raw poultry might be a route of transmission. public education and administrative measures have also led to a slow change in eating habits from live chicken to chilled or frozen chicken. to reduce the contact between human beings and poultry in hong kong, the hong kong government implemented a voluntary surrender scheme in , and subsequently a buyout scheme in for poultry retailers, wholesalers, transporters, and farmers. in , domestic households were prohibited to keep any live poultry. with these measures, between and , the number of local poultry farms in hong kong decreased from about to and the number of retail poultry stalls decreased from about to . since , the number of imported live chickens was reduced from about per day to per day. enhanced surveillance of h n and h n in both live and dead wild birds, farm, and market poultries might be important for geographical areas along the migratory route of wild birds. with these measures, no local cases of h n in hong kong have been identifi ed since , despite the failure to implement central slaughtering because of cultural resistance. the h n outbreak in human beings resembles the h n outbreak in many ways, including substantial mortality associated with severe pneumonia, multiorgan dysfunction, and cytokine dysregulation, appearance in cities along the route of migratory birds with high density of poultry, predominant poultry-to-human transmission, and the predilection for the lower respiratory tract. , the high proportion of elderly men infected with h n could be attributable to diff erent social circumstances leading to this age and sex bias. the rapid increase in human beings infected with severe h n to more than cases within months from march to may, , is unprecedented for avian infl uenza viruses and could be related to enhanced transmissibility from poultry to human or improved virological testing. however, h n is diffi cult to control because fl ock die-off did not precede human cases. stringent measures to control the poultry outbreak will stop the human epidemic and perhaps decrease the risk of h n evolving to become a pandemic agent. even though this dangerous scenario has not happened with h n , the virus has spread from hong kong to the whole of china, southeast asia, middle east, and africa. although the number of human beings infected with h n was greatly reduced in may (possibly related to the rising ambient temperature or the epidemiological control measures in live poultry markets), high vigilance is still needed in view of the interval of months between the fi rst and second h n human case. biosecurity measures for live poultry markets, farms, and traffi cking should be commensurate with increasing demand for poultry. transmission cycles within markets or between markets and farms could be interrupted by a no overnight poultry policy with daily poultry-stall cleansing and ultimately central slaughtering in cities. precautionary research and development of poultry and human h n vaccines are important. control in rural areas with many backyard farms relies on poultry vaccination. virological surveillance of wild birds and domestic poultry in farms and markets is important in understanding the emergence of the h n and other avian infl uenza viruses. over years from to , the consumption of poultry in hong kong has tripled to kg per person per year. in , the consumption of poultry in china reached kg per person per year, and the mainland cities such as shanghai are likely to catch up with the amount of consumption in hong kong in coming years (fi gure ). increasing problems with avian infl uenza in poultry and human beings are anticipated. we declare that we have no confl icts of interest. a/mallard/ohio/ os / (h n ) a/common goldeneye/wisconsin/ os / (h n ) a/northern pintail/illinois/ os / (h n ) a/chicken/new york/sg- / (h n ) a/american black duck/maryland/ / (h n ) a/ruddy turnstone/delaware bay/ / (h n ) a/northern shoveler/california/ - / (h n ) a/american green-winged teal/california/ / (h n ) a/starling/victoria/ / (h n ) a/turkey/england/ / (h n ) a/duck/hong kong/ / (h n ) a/turkey/ireland/pv / (h n ) a/duck/hokkaido/w / (h n ) a/duck/taiwan/ / (h n ) a/duck/hokkaido/ / (h n ) a/duck/korea/bc / (h n ) a/mallard/geumgang/ / (h n ) a/duck/mongolia/ / (h n ) a/magpie/korea/yjd / (h n ) a/duck/tsukuba/ / (h n ) a/duck/zhejiang/ / (h n ) a/hangzhou/ / (h n ) a/duck/korea/a / (h n ) a/chicken/new jersey/sg- / (h n ) a/chicken/pennsylvania/ / (h n ) a/duck/zhejiang/ / (h n ) a/chicken/california/ / (h n ) a/ruddy turnstone/new jersey/ / (h n ) a/starling/victoria/ (h n ) a/wild goose/dongting/pc / (h n ) a/duck/mongolia/ / (h n ) a/duck/hong kong/ / (h n ) a/turkey/france/ / (h n ) a/shearwater/australia/ / (h n ) a/swan/shimane/ / (h n ) a/pintail/shimane/ / (h n ) a/duck/mongolia/ / (h n ) a/duck/hunan/ / (h n ) a/duck/vietnam/g / (h n ) a / (h n ) a/hangzhou/ / (h n ) clinical features and rapid viral diagnosis of human disease associated with avian infl uenza a h n virus avian infl uenza a h n virus: a continuous threat to humans world health organization. cumulative number of confi rmed human cases for avian infl uenza a(h n ) reported to who laboratory-confi rmed case of human infection with avian infl uenza a(h n ) virus in taiwan recovered; taiwan cdc urges public to take precautions to stay healthy low pathogenic avian infl uenza a (h n ) virus infection in immunocompromised adult infl uenza virus a (h n ) in chickens and poultry abattoir workers human illness from avian infl uenza h n , british columbia infection of immunocompromised patients by avian h n infl uenza a virus avian infl uenza a virus (h n ) associated with human conjunctivitis and a fatal case of acute respiratory distress syndrome chinese center for disease control and prevention. questions and answers about human infection witha(h n ) avian infl uenza virus human infections with the emerging avian infl uenza a h n virus from wet market poultry: clinical analysis and characterisation of viral genome human infection with a novel avian-origin infl uenza a (h n ) virus the fi rst case of h n infl uenza in taiwan preliminary report: epidemiology of the avian infl uenza a (h n ) outbreak in china clinical fi ndings in cases of infl uenza a (h n ) virus infection shanghai reports h n death world health organization. global alert and response disease outbreak news. human infection with avian infl uenza a(h n ) virus-update mapping the h n avian fl u outbreaks two years after pandemic infl uenza a/ /h n : what have we learned? a distinct lineage of infl uenza a virus from bats structural and functional characterization of neuraminidase-like molecule n derived from bat infl uenza a virus identifi cation of novel infl uenza a virus proteins translated from pa mrna emergence of multiple genotypes of h n avian infl uenza viruses in hong kong sar characterization of the infl uenza a virus gene pool in avian species in southern china: was h n a derivative or a precursor of h n ? origin and diversity of novel avian infl uenza a h n viruses causing human infection: phylogenetic, structural, and coalescent analyses evolutionary characteristics of a/hangzhou/ / and source of avian infl uenza virus h n subtype in china genetic characterization of h n infl uenza virus isolated from pigs ministry of agriculture of the people's republic of china environmental connections of novel avianorigin h n infl uenza virus infection and virus adaptation to the human severe acute respiratory syndrome coronavirus-like virus in chinese horseshoe bats no h n virus found in poultry farms: moa characterization of avian h n infl uenza viruses from poultry in hong kong avian infl uenza. manual of diagnostic tests and vaccines for terrestrial animals avian infl uenza virus hemagglutinins h , h , h , and h support a highly pathogenic phenotype genetic analysis of novel avian a(h n ) infl uenza viruses isolated from patients in china emergence of avian infl uenza a (h n ) virus causing severe human illness-china intersegmental recombination between the haemagglutinin and matrix genes was responsible for the emergence of a highly pathogenic h n avian infl uenza virus in british columbia sequence and phylogenetic analysis of h n avian infl uenza viruses isolated from poultry in china in strategies and challenges for eliciting immunity against avian infl uenza virus in birds interspecies transmission and emergence of novel viruses: lessons from bats and birds avian fl u: infl uenza virus receptors in the human airway identifi cation of amino acids in ha and pb critical for the transmission of h n avian infl uenza viruses in a mammalian host egyptian h n infl uenza viruses-cause for concern live-animal markets and infl uenza a (h n ) virus infection quantitative description of glycan-receptor binding of infl uenza a virus h hemagglutinin experimental adaptation of an infl uenza h ha confers respiratory droplet transmission to a reassortant h ha/h n virus in ferrets airborne transmission of infl uenza a/h n virus between ferrets glycan receptor binding of the infl uenza a virus h n hemagglutinin length variations in the na stalk of an h n infl uenza virus have opposite eff ects on viral excretion in chickens and ducks biochemical impact of the host adaptation-associated pb e k mutation on the temperature-dependent rna synthesis kinetics of infl uenza a virus polymerase complex human ha and polymerase subunit pb proteins confer transmission of an avian infl uenza virus through the air properties and dissemination of h n viruses isolated during an infl uenza outbreak in migratory waterfowl in western china transmission of infl uenza virus in a mammalian host is increased by pb amino acids k or e/ n a new infl uenza virus virulence determinant: the ns protein four c-terminal residues modulate pathogenicity large-scale sequence analysis of avian infl uenza isolates two amino acid residues in the matrix protein m contribute to the virulence diff erence of h n avian infl uenza viruses in mice update: infl uenza activity-united states, - season assessing the role of contact tracing in a suspected h n infl uenza a outbreak in humans in wales serological analysis of serum samples from humans exposed to avian h infl uenza viruses in italy between and outbreak of low pathogenicity h n avian infl uenza in uk, including associated case of human conjunctivitis update on human cases of infl uenza at the human-animal interface conjunctivitis in human beings caused by infl uenza a virus of seals avian infl uenza virus isolated from a woman with conjunctivitis pandemic infl uenza: a zoonosis? serologic study for infl uenza a (h n ) among high-risk groups in china characterization of an avian infl uenza virus of subtype h n isolated from chickens in northern china seroprevalence and genetic characteristics of fi ve subtypes of infl uenza a viruses in the chinese pig population: a pooled data analysis a survey of avian infl uenza in tree sparrows in china in low pathogenic h subtype avian infl uenza viruses isolated from domestic ducks in south korea and the close association with isolates of wild birds and their relationships with korean isolates from domestic poultry and wild birds avian infl uenza in north america infl uenza a viruses from wild birds in guatemala belong to the north american lineage hofl e u. detection of low pathogenic avian infl uenza viruses in wild birds in castilla-la mancha (south central spain) outbreak of avian infl uenza a(h n ) virus infection in hong kong in shanghai municipal health and family planning commission demographic trends in hong kong case-control study of risk factors for avian infl uenza a (h n ) disease, hong kong update: who-confi rmed human cases of avian infl uenza a (h n ) infection monitoring avian infl uenza a(h n ) virus through national infl uenza-like illness surveillance avian infl uenza a(h n ) virus infections original antigenic sin responses to infl uenza viruses virus-host interactions and the unusual age and sex distribution of human cases of infl uenza a(h n ) in china high titer and avidity of nonneutralizing antibodies against infl uenza vaccine antigen are associated with severe infl uenza severe pandemic h n infl uenza disease due to pathogenic immune complexes interferon-induced transmembrane protein- genetic variant rs -c is associated with severe infl uenza in chinese individuals a functional variation in cd increases the severity of pandemic h n infl uenza a virus infection h n mystery: why does age profi le tilt older? infectivity, transmission, and pathology of human h n infl uenza in ferrets and pigs genetic data provide evidence for wind-mediated transmission of highly pathogenic avian infl uenza infectivity of h lp and hp infl uenza viruses at diff erent temperatures and ph and persistence of h hp virus in poultry meat at refrigeration temperature transcript of media briefi ng by dr michael o'leary, who representative in china probable limited person-to-person transmission of highly pathogenic avian infl uenza a (h n ) virus in china united states department of agriculture foreign agricultural service. production, supply, and distribution online database poultry sector in china: structural changes during the past decade and future trends impact of vaccines and vaccination on global control of avian infl uenza human co-infection with novel avian infl uenza a h n and infl uenza a h n viruses in jiangsu province evaluation of analytical sensitivity of seven point-of-care infl uenza detection kits and two molecular tests for detection of avian-origin h n and swine-origin h n variant infl uenza a viruses association between adverse clinical outcome in human disease caused by novel infl uenza a h n virus and sustained viral shedding and emergence of antiviral resistance neuraminidase sequence analysis and susceptibilities of infl uenza virus clinical isolates to zanamivir and oseltamivir impact of neuraminidase inhibitor treatment on outcomes of public health importance during the - infl uenza a (h n ) pandemic: a systematic review and meta-analysis in hospitalized patients clinical effi cacy of long-acting neuraminidase inhibitor laninamivir octanoate hydrate in postmarketing surveillance long-acting neuraminidase inhibitor laninamivir octanoate versus oseltamivir for treatment of infl uenza: a double-blind, randomized, noninferiority clinical trial newer infl uenza antivirals, biotherapeutics and combinations thiazolides, a new class of anti-infl uenza molecules targeting viral hemagglutinin at the post-translational level the lipid mediator protectin d inhibits infl uenza virus replication and improves severe infl uenza obatoclax, saliphenylhalamide, and gemcitabine inhibit infl uenza a virus infection effi cacy of combined therapy with amantadine, oseltamivir, and ribavirin in vivo against susceptible and amantadine-resistant infl uenza a viruses delayed antiviral plus immunomodulator treatment still reduces mortality in mice infected by high inoculum of infl uenza a/h n virus eff ect of immunomodulatory therapies in patients with pandemic infl uenza a (h n ) complicated by pneumonia hyperimmune intravenous immunoglobulin treatment: a multicentre double-blind randomized controlled trial for patients with severe a(h n )pdm infection convalescent plasma treatment reduced mortality in patients with severe pandemic infl uenza a (h n ) virus infection hoff man sl. meta-analysis: convalescent blood products for spanish infl uenza pneumonia: a future h n treatment? treatment with convalescent plasma for infl uenza a (h n ) infection referral to an extracorporeal membrane oxygenation center and mortality among patients with severe infl uenza a(h n ) a model to control the epidemic of h n infl uenza at the source avian infl uenza and ban on overnight poultry storage in live poultry markets, hong kong h n is a virus worth worrying about we thank wing-man ko of the food and health bureau of the hong kong special administrative region for helping with some data collection in this manuscript. hc is partially supported by the areas of excellence of the university grants committee (grant key: cord- -n fpu s authors: Álvarez, e.; donado-campos, j.; morilla, f. title: new coronavirus outbreak. lessons learned from the severe acute respiratory syndrome epidemic date: - - journal: epidemiol infect doi: . /s x sha: doc_id: cord_uid: n fpu s system dynamics approach offers great potential for addressing how intervention policies can affect the spread of emerging infectious diseases in complex and highly networked systems. here, we develop a model that explains the severe acute respiratory syndrome coronavirus (sars-cov) epidemic that occurred in hong kong in . the dynamic model developed with system dynamics methodology included variables (five states, four flows, eight auxiliary variables, six parameters), five differential equations and algebraic equations. the parameters were optimized following an iterative process of simulation to fit the real data from the epidemics. univariate and multivariate sensitivity analyses were performed to determine the reliability of the model. in addition, we discuss how further testing using this model can inform community interventions to reduce the risk in current and future outbreaks, such as the recently middle east respiratory syndrome coronavirus (mers-cov) epidemic. middle east respiratory syndrome (mers), is a respiratory illness caused by a novel coronavirus (cov) [ ] . the disease was reported for the first time in saudi arabia in june and spread to several countries in africa, asia, americas and europe [ , ] . the capability of human-to-human transmission has been observed in at least four hospital settings [ ] [ ] [ ] [ ] . significantly, mers-cov shares certain similarities with the severe acute respiratory syndrome (sars)-cov that produced a global epidemic with more than human cases in - [ , ] . first, a number of patients infected with both viruses developed an acute respiratory disease that in some cases resulted in death [ , ] . in this sense, mers-cov appears to be highly pathogenic with an estimated case-fatality rate of around %, although this might be an overestimation as many infected patients may not have sought hospital assistance [ ] . second, both mers-cov and sars-cov, belong to the genus betacoronavirus and are closely related to coronaviruses isolated from bats [ ] [ ] [ ] . this strongly suggests that mers-cov and sars-cov may have been transmitted from bats to humans through intermediate species (e.g. camels for mers-cov and civet cats for sars-cov). third, since they are new emerging viruses, there are no effective vaccines or antiviral treatments. the sars epidemic is a clear example of how a networked health system can respond to a new threat to human health. one of the best-characterized outbreaks during the sars epidemic was in hong kong in where there were confirmed cases with deaths (who; http://www.who.int/csr/sars/country/en/index. html). the outbreak began in mid-february caused by an infected person who travelled from guangdong to hong kong [ ] . an important fact in the generation of a model of the outbreak is that the hong kong health authorities quickly implemented contagion control procedures [ ] . in general, two interventions were introduced to prevent the spread of sars-cov. the first was implementation of quarantine measures to isolate healthy people who had been in contact with infected people and therefore potentially in contact with the virus; isolating those that could be infected and asymptomatic during the incubation period and isolating and treating patients who had developed the disease. the other intervention was the application of protective measures by healthy people who were in contact with infected people to avoid becoming infected, such as respiratory protection for healthcare workers and daily disinfection of the environment of affected rooms [ ] . these control interventions were implemented progressively in the hong kong special administrative region from mid-march to late april [ ] . the application of these procedures allowed the rapid control of the outbreak in the subsequent months. in this sense, it is estimated that the epidemic in hong kong ended in late june. system dynamics has been proved to be a powerful instrument for analysing social, economic, ecological and biological systems [ ] . in addition, disease epidemiology has been studied using this approach, whereby system dynamics offers the practical application of concepts by computerized models that allow the systematic test of different scenarios and alternative policies [ ] [ ] [ ] . in this work, we performed a modelling of the hong kong sars-cov outbreak using system dynamics. the developed model contains five states, four flows, eight auxiliary variables and six parameters that interact through five differential and algebraic equations. the parameters of the model were optimized following an iterative process of simulation to obtain a model that largely fits the data available to the epidemic. moreover, the credibility of our model and its parameters are supported by both univariate and multivariate sensitivity analyses. the model reproduces how the implementation of control measures was effective in preventing the spread of infection to the rest of the population. basically, these measures result in a sustained reduction in the frequency of contacts. at present, the application of similar measures for infection containment can help to prevent the spread of new emerging epidemics, such as the outbreak caused by mers-cov. data on the total population of hong kong in was obtained from statistics of the census and statistic department, the government of the hong kong special administrative region (http://www.censtatd.gov.hk/home/). data on cumulative cases, deaths and recoveries during the sars epidemics in hong kong was obtained from global alert and response databases of the who (http://www.who. int/csr/sars/country/en/index.html). the model was developed following the four-step sequence proposed by system dynamics methodology [ ] . first, the real data from the hong kong sars epidemics ( fig. ) together with other evidences and our professional experience were used to create a mental modelling of the reality of the outbreak. second, the model structure that is able to explain the evolution of the epidemics was represented as a forrester diagram (fig. ) . third, the outbreak was mathematically modelled as a continuous dynamic process represented by a set of differential and algebraic equations (tables - ) . finally, the model was optimized to fit the real data from figure . a dynamic compartmental model provides a framework for the study of transport between different compartments of a system, i.e. well known epidemiological compartmental models [ ] . to explain how the protective measures taken by the government of hong kong allowed the rapid control of the epidemic we consider a dynamic model with five compartments (states) and four transitions (physical flows) between them. this model is based on two assumptions. first, the individuals are classified into five subgroups (susceptible, latent, infected, recovered, dead). although, the last subgroup is not strictly needed, it is used to keep an account of those dead. second, every day there is a different number of people: who are infected without symptoms of the disease (incidence); who develop signs and symptoms of the illness (sick per day); who recover from the disease (daily recovered), and who die (daily deaths) as consequence of the outbreak. the model structure built with vensim software (ventana systems inc., usa) ( fig. ) contains the five states and the four flows mentioned above and also eight auxiliary variables (inside circles) and six parameters (in bold). these elements are linked by the physical flows (double line with arrow) and by the information transmissions (single line with arrow) according to the mathematical model represented by the set of differential and algebraic equations (tables - ). the five differential equations in table establish the mass balance (inflows minus outflows) in the compartments, and as such, they describe the changes in the number of people (stocks) in the five subgroups. the four algebraic equations of table express that the physical transitions depend directly from the stock in the compartment of origin and indirectly from other stocks and parameters through the corresponding auxiliary variables. these equations involve three stocks (susceptible, latent, infected), three auxiliary variables (prevalence, contagion rate, recovery rate) and three parameters (incubation period, case fatality, disease duration). for instance, the incidence flow is proportional to the number of susceptible people, the prevalence and the contagion rate. the contagion rate or transmission coefficient ( ) prevalence recovery rate recovery rate(t) = ( − case fatality)/(disease duration) contagion rate contagion rate(t) = frequency of contacts(t) × infectivity cumulative cases cumulative cases(t) = dead(t) + recovered(t) + infected(t) people ( ) cumulative attack rate cumulative attack rate (t) = cumulative cases(t)/population(t) dimensionless ( ) frequency of contacts frequency of contacts(t) = daily contacts /( + (cumulative attack rate/ threshold of cumulative attack rate) ) basic reproductive number(t) = contagion rate(t)/recovery rate(t) dimensionless theoretically depends on the number of contacts per unit time and the probability of effective contact, i.e. the probability that a contact between an infectious source and susceptible host results in a successful transfer whereby the susceptible host becomes infected. the first three algebraic equations of table express the auxiliary variables (prevalence, contagion rate, recovery rate) used in the equations of table . in turn, these depend on other auxiliary variables, stocks and parameters. for instance, prevalence is defined as the ratio between number of infected people and the total population [ table , equation ( )]. the recovery rate depends on the illness duration and case fatality [ table , equation ( )]. equation ( ) in table expresses the contagion rate which is directly dependent on the auxiliary variable 'frequency of contacts' and the parameter 'infectivity'. one of the key variables in the model is frequency of contacts because it tries to reproduce the control measures carried out by the hong kong government to control the sars outbreak. we assumed that: ( ) the control measures gave, as consequence, a marked reduction of daily contacts in hong kong; ( ) the control measures were based on the cumulative attack rate, measured as the ratio between cumulative cases and total population [ table , equation ( )]. therefore, we decided to use the frequency of contacts as the daily contacts modulated by the repression hill function (fig. ), in accordance with the equation ( ) of table . despite the complexity level of biological systems several cases have been modelled using the hill function, in order to simulate repressor activities of enzymatic reactions and the regulation mechanisms of several transcription factors [ ] . in our model this repressor function allows the establishment of the relationship between frequency of contacts and the cumulative attack rate. note that the cumulative attack rate is used as an active repressor, so halfmaximal repression occurs when the cumulative attack rate is equal to the threshold, and almost total repression occurs when this cumulative attack rate is double the threshold. equation ( ) in table is used to report on the basic reproductive number (r ), which is defined as the expected number of secondary infectious cases generated by an average infectious case in an entirely susceptible population [ ] . in our model this number is calculated as the ratio between the contagion rate and the recovery rate. if r < , then the infected individuals in the total population fail to replace themselves, and the disease does not spread. however, if r > , the number of cases generally increases over time and the disease spreads. one of the most challenging issues in system dynamics modelling is to establish the value of the model parameters. the parameters can be estimated taking advantage of the known information available in the literature and can be optimized by means of an iterative process of simulation. using this approach, we set values for the six parameters of our model which are summarized in table . infectivity expresses the ability of the pathogen to penetrate, survive and multiply in the host and it is measured through the secondary attack rate which is defined as the probability that infection occurs in susceptible persons within a reasonable incubation period following known contact with an infectious person or an infectious source. epidemiological studies in ( ) of table ]. the dotted line corresponds to the threshold repression function (when n tends to infinity). the representation is normalized to the threshold of cumulative attack rate on the abscissa axis and the value of the discontinuity (daily contacts) on the ordinate axis. singapore showed that % of individuals infected with sars-cov did not cause secondary infections, suggesting low infectivity [ ] . after the optimization process, the final value set for infectivity was · , which is in agreement with a previous work examining the probability of transmission for sars-cov [ ] . the incubation period of the disease, during which time the individual is asymptomatic appears to be between and days with an average value of · days [ ] . similarly, although the duration of the disease is variable depending on the case, the average of the most severe and the mildest cases is days [ ] . during this time period the virus can be transmitted to other people. several studies have shown that the case fatality of sars-cov was also variable in the outbreak depending on different factors. it has been estimated that the mean case fatality for sars in hong kong was around · [ ] . social contact patterns have been shown to be highly relevant on the transmission dynamics of respiratory infections such as measles, rubella and influenza [ ] [ ] [ ] . quantifying this parameter is critical for estimating the impact of such infections, for designing and targeting preventive interventions, and for modelling their impact. in our model the daily contacts parameter, indicating the mean number of contacts of a person in day, was set to · after the optimization process, which is in agreement with previous studies quantifying these social mixing patterns [ , ] . the parameter 'threshold of cumulative attack rate' is critical in our model since it allows setting the value of the cumulative attack rate at which control measures were established by the hong kong authorities. this parameter was finally set at · × − . therefore, according to the hill function of figure , for any number of the cumulative attack rate below the cases by million, the frequency of contacts will be greater than · (half of the daily contacts), and in the opposite case the frequency of contacts will be markedly reduced. as explained before, our dynamic model was subjected to successive rounds of simulation and optimization in order to fine-tune the parameters of the model. in all these simulations we assumed that the hong kong epidemic originated from a traveller from guangdong in china [ ] , and at the beginning of the outbreak the entire population of hong kong was susceptible to sars-cov infection. these assumptions are represented by the initial values in the five stocks (table ) . moreover, based on the reported data, the simulation period was set to days with a time step of day. parameters of system dynamics models are subject to uncertainty. sensitivity analyses were conducted to provide insight into how uncertainty in the parameters affects the model outputs and which parameters tend to drive these variations. in this task it is essential to define the probabilistic distribution patterns of the model parameters, which are shown in table , together with the references that support these patterns. the most influential parameters were estimated by univariate analyses, in which changes in the model output were studied after disturbance in each parameter value independently. in complex models, univariate sensitivity analysis can be insufficient for a comprehensive study of the model. simultaneous fluctuations in the value of more than one parameter may create an unexpected output change due to nonlinear relationships in different model components. thus, to test the influence of simultaneous changes in the model parameters, the univariate analyses were followed by monte-carlo multivariate sensitivity analysis, in which the values of the six parameters were altered at the same time. modelling process, simulations and sensitivity analyses were performed using vensim dss software v. . a (ventana systems). figure shows a graphic comparison between the simulation results using the parameters of table and the real data of the hong kong outbreak. we compared only the variables of the model for which records were found in the public databases, which are the same six variables shown in figure . the simulation output for the variable 'sick per day' fit the data reported by the hong kong authorities (fig. a) , suggesting that the model was able to reproduce the epidemic curve. we observed that the number of new cases per day obtained in the simulation grew during the first days. from this time, the number of new infections gradually fell to values < at later stages of the outbreak. as a consequence, the auxiliary variable that stores the cumulative sars cases showed a characteristic sigmoidal growth (fig. b) , consistent with the real data. we observed that the number of sars cases grew from one at the beginning of the epidemic to around at the final stage of the outbreak, similar to the cases reported by the authorities. moreover, we observed a high fit between the model predictions and the real data. as expected, the number of deaths and recovered people in the simulation also grew with a sigmoidal shape to reach values similar to those found in the public databases (fig. c, d) . however, we observed a partial fit of these stock variables to the data reported during the outbreak. these slight mismatches were also observed in the flow variables for recovered and daily deaths (fig. e , f) that may be due to delays in reporting of cases by the authorities. in short, looking the simulation results of figure we can conclude that our model is able to reproduce largely the most important indicators of the sars epidemic that occurred in hong kong in . focusing on the evolution of the basic reproduction number (fig. ) , we note that during the early stages of the epidemic, r > , which is consistent with the observed disease spread. moreover, after day , r starts to drop to values < , probably due to the implementation of containment measures by the hong kong authorities after the issuance of the first global alert against sars on march . these results are consistent with a previous report showing the basic reproductive numbers for different sars epidemic curves, which supports the notion that our model is able to largely replicate the disease outbreak in hong kong [ ] . the results of the univariate sensitivity analysis are shown in figure . we focused our attention on the epidemic wave although the analysis is possible in other variables, as shown in the multivariate analysis of figure . variations in case fatality, threshold of cumulative attack rate and disease duration induced little changes in the epidemic curve (fig. -c) , while more extensive alterations in the epidemic wave were observed after changes in infectivity, daily contacts and incubation period (fig. d-f) . variations in the case-fatality parameter do not alter the output of the variable sick per day (fig. a) , although other variables from the model such as recovered and dead are highly impacted (data not shown). small changes in the shape and the maximum of the curve are observed after modification of the parameters 'threshold of cumulative attack rate' and 'disease duration' (fig. b, c) . by contrast, changes in infectivity, daily contacts and to a lesser extent in incubation period significantly alter both the position and height of the maximum of the epidemic curve (fig. d-f ) . the results of the multivariate sensitivity analysis are shown in figure , we analysed the output of four variables: sick per day, infected, recovered, and dead ( fig. a-d, respectively) . variations in the model parameters clearly change the shape of the epidemic curve, altering both the position and the height of the maximum of this variable (fig. a) . similarly, the output of the variables infected and recovered is highly impacted by the changes in parameters carried out in the multivariate sensitivity analysis (fig. b, c) . the alterations of variable outputs are clearly exemplified by the variable 'dead' (fig. d) . certain changes in the parameters of the model can explain an increase in the total number deaths during the epidemic rising from about to about . the observed variations in model output when the value of the parameters is changed support the idea that this model might be able to simulate different scenarios and epidemic conditions. system dynamics modelling has been successfully applied to study complex public health issues such as the design of optimal policies in healthcare [ ] , the impact of public health intervention in different situations [ , ] , and to study disease epidemiology [ ] [ ] [ ] . in the latter, system dynamics technology has become a powerful tool to understand and predict the impact of infectious diseases. epidemiological models can help health authorities to make recommendations regarding intervention to fight the spread of directly transmissible pathogens, especially when empirical data is limited. in this sense, mathematical models have been previously used to advise health policies against diseases such as pandemic influenza [ , ] and sars [ , , ] . several models studying sars transmission and interventions have been published. these are detailed hybrid stochastic and compartmental models that successfully explain the behaviour of the epidemic [ , , ] . here, trying to follow ockham's razor principle, we have built a simpler deterministic model, which is also able to reproduce the behaviour of the epidemic based on its natural history and the intervention measures taken in hong kong. the use of a less complicated model could be helpful in understanding the disease epidemic and also facilitating its reuse under other conditions. the epidemiological models depend on the consistency of the chosen parameters. therefore, the accurate quantification of these parameters is critical to estimate the path of a disease, to predict the impact of possible interventions, and to inform planning and decision making. here, we have combined reported information from the sars epidemic with an iterative optimization process to set the final values for the model parameters. under these conditions, the model output fits the epidemic curve observed in the hong kong sars-cov outbreak (fig. ) . of the factors that influence the dynamics of infectious diseases, the person-to-person contact pattern has been shown to be essential in disease spread [ ] . our model takes this essential factor into account through the auxiliary variable 'frequency of contacts', which is dependent on the auxiliary variable 'cumulative attack rate' and the parameters 'daily contacts' and 'threshold of cumulative attack rate' (fig. ) . a previous work showed that mixing patterns and contact characteristics were remarkably similar across the different european countries analysed in that table . the solid black line represents the simulation output and the grey area represents the % confidence bounds. study even though the average number of contacts recorded differed. interestingly, the authors suggests that the results may well be applicable to other countries with similar social structures, and that the initial epidemic phase of an emerging infection in susceptible populations, such as sars was in , is likely to be very similar [ ] . during the sars outbreak, health authorities, hospitals, and the overall population progressively implemented quarantine and protection policies to prevent the transmission of the disease [ ] . with this in mind, we made the assumption that the intervention of the health authorities caused a decrease in the frequency of contacts, which in turn led a decrease in the rate of contagion. to mimic this event in our model, the number of daily contacts is regulated by means of a repression hill function, which has been used to simulate repressor activities in complex biological systems [ ] . the basic reproductive number is a key epidemiological variable that characterizes the potential of a disease to spread. several works have estimated that prior to the first global alert the basic reproductive number for sars was > , correlating with an exponential increase in the number of cases. however, the implementation of effective control measures, such as quarantine, isolation, and strict hygiene practice in hospitals led a sudden decrease in r [ , ] . the fact that, in our model, r drops to values < around the date of the global alert reinforces the idea that a decrease in the frequency of contacts is able to effectively simulate the effects of the control measures established in the first stages of the epidemic. it is important to note that estimations of r in previous publications are considerably lower (around - ) than ours, which is almost at the beginning of the outbreak [ , , ] . nevertheless, the estimated value of r also differs in these works and the credible intervals surrounding these deterministic estimations were wide, reaching superior values of almost . this high variability can be explained in part by the superspreading events that occurred in sars epidemics. superspreading is an unusual situation, in which a single individual directly infects a large number of other people that has a large influence on the early course of the epidemic [ ] . interestingly, the fact that our model does not explicitly account these events could partially explain the very high estimated value of r at the beginning of the outbreak. the reliability of the model parameters is supported by univariate and multivariate sensitivity analyses (figs and ) . furthermore, sensitivity analysis is a powerful tool to analyse the influence of certain decision making in the evolution of the epidemic. taken together, these findings strongly suggest that table . the solid black line represents the simulation output and the grey area represents the % confidence bounds. our model, together with other system dynamics models can be used by epidemiologists to investigate the likely consequences of future re-emergences of sars-cov based on analysis of the previous known epidemics. in addition, by adapting the key parameters of these models or with a little change in the model structures, they can be used to face emerging outbreaks of infectious diseases, such as the recent mers-cov epidemic. in this regard, there are several similarities and differences which should be taken into account when using this model. both sars-cov and mers-cov may cause severe respiratory failure, extrapulmonary features such as diarrhoea and also mild or asymptomatic cases. in contrast with sars, mers has lower human-to-human transmission potential, affects predominantly older people with more comorbid illness and has a higher case-fatality rate [ ] . these factors would affect the output of the model variables (e.g. epidemic curve, cumulative cases, number of dead, etc.). middle east respiratory syndrome coronavirus (mers-cov): announcement of the coronavirus study group update: severe respiratory illness associated with middle east respiratory syndrome coronavirus (mers-cov) -worldwide isolation of a novel coronavirus from a man with pneumonia in saudi arabia evidence of person-to-person transmission within a family cluster of novel coronavirus infections hospital outbreak of middle east respiratory syndrome coronavirus first cases of middle east respiratory syndrome coronavirus (mers-cov) investigations and implications for the prevention of human-to-human transmission clinical features and virological analysis of a case of middle east respiratory syndrome coronavirus infection the genome sequence of the sars-associated coronavirus coronavirus as a possible cause of severe acute respiratory syndrome human betacoronavirus c emc/ -related viruses in bats, ghana and europe full-genome deep sequencing and phylogenetic analysis of novel human betacoronavirus bats are natural reservoirs of sars-like coronaviruses update: outbreak of severe acute respiratory syndrome-worldwide transmission dynamics of the etiological agent of sars in hong kong: impact of public health interventions monitoring the severe acute respiratory syndrome epidemic and assessing effectiveness of interventions in hong kong special administrative region business dynamics: systems thinking and modeling for a complex world system dynamics modeling for public health: background and opportunities understanding diabetes population dynamics through simulation modeling and experimentation new data and tools for integrating discrete and continuous population modeling strategies infectious diseases of humans: dynamics and control modeling and analysis of the dynamic behavior of the xlnr regulon in aspergillus niger severe acute respiratory syndrome-singapore estimating variability in the transmission of severe acute respiratory syndrome to household contacts in hong kong bayesian modelling of an epidemic of severe acute respiratory syndrome the mixed trunsored model with applications to sars measles in england and wales-i: an analysis of factors underlying seasonal patterns quantitative investigations of different vaccination policies for the control of congenital rubella syndrome (crs) in the united kingdom age-related changes in the rate of disease transmission: implications for the design of vaccination programmes who mixes with whom? a method to determine the contact patterns of adults that may lead to the spread of airborne infections social contacts and mixing patterns relevant to the spread of infectious diseases different epidemic curves for severe acute respiratory syndrome reveal similar impacts of control measures using system dynamics to help develop and implement policies and programmes in health care in england work disability related to musculoskeletal pain: a system dynamics approach evaluating hmo policies with a computer simulation model prevention and rehabilitation as a means of cost containment: the example of myocardial infarction modelling the epidemiological consequences of hiv infection and aids: a contribution from operational research model based scenarios for the epidemiology of hiv/aids: the consequences of highly active antiretroviral therapy containing pandemic influenza at the source cost-effective strategies for mitigating a future influenza pandemic with h n characteristics real-time estimates in early detection of sars entry screening for severe acute respiratory syndrome (sars) or influenza: policy evaluation transmission dynamics and control of severe acute respiratory syndrome mathematical models of infectious disease transmission severe acute respiratory syndrome vs. the middle east respiratory syndrome this research was supported by an intramural contract from universidad autónoma de madrid awarded to e. Álvarez. the institutional grant awarded to the centro de biología molecular 'severo ochoa' by the fundación ramón areces is also acknowledged. none. key: cord- - t wpiqy authors: webby, rj; perez, dr; coleman, js; guan, y; knight, jh; govorkova, ea; mcclain-moss, lr; peiris, js; rehg, je; tuomanen, ei; webster, rg title: responsiveness to a pandemic alert: use of reverse genetics for rapid development of influenza vaccines date: - - journal: lancet doi: . /s - ( ) - sha: doc_id: cord_uid: t wpiqy background: in response to the emergence of severe infection capable of rapid global spread, who will issue a pandemic alert. such alerts are rare; however, on feb , , a pandemic alert was issued in response to human infections caused by an avian h n influenza virus, a/hong kong/ / . h n had been noted once before in human beings in and killed a third ( / ) of infected people. , the variant seemed to have been transmitted directly from birds to human beings and caused fatal pneumonia in one of two infected individuals. candidate vaccines were sought, but no avirulent viruses antigenically similar to the pathogen were available, and the isolate killed embryonated chicken eggs. since traditional strategies of vaccine production were not viable, we sought to produce a candidate reference virus using reverse genetics. methods: we removed the polybasic aminoacids that are associated with high virulence from the haemagglutinin cleavage site of a/hong kong/ / using influenza reverse genetics techniques. a reference vaccine virus was then produced on an a/puerto rico/ / (pr ) backbone on who-approved vero cells. we assessed this reference virus for pathogenicity in in-vivo and in-vitro assays. findings: a reference vaccine virus was produced in good manufacturing practice (gmp)-grade facilities in less than weeks from the time of virus isolation. this virus proved to be non-pathogenic in chickens and ferrets and was shown to be stable after multiple passages in embryonated chicken eggs. interpretation: the ability to produce a candidate reference virus in such a short period of time sets a new standard for rapid response to emerging infectious disease threats and clearly shows the usefulness of reverse genetics for influenza vaccine development. the same technologies and procedures are currently being used to create reference vaccine viruses against the h n viruses circulating in asia. in february, , two family members were admitted to intensive care wards in hong kong special administrative region with influenza-like respiratory illness. avian-like h n influenza viruses were isolated from both patients, one of whom succumbed to infection. this was the first time since that h n viruses had been identified in human beings, and who responded by issuing a pandemic alert. candidate vaccines were immediately sought. the recent outbreak of severe acute respiratory syndrome (sars) had been a striking example of the rapid and global spread of an emerging infectious disease. however, even the effects of sars could be dwarfed by those that could arise with the emergence of an influenza pandemic. infection caused by the influenza a virus is a zoonosis, and the animal reservoir of this virus is the aquatic bird populations of the world. the compelling epidemiological link between the presence of the virus in poultry in live-bird markets and the appearance of h n in human beings in suggested that influenza a viruses can be transmitted directly from avian species to man and can cause severe respiratory disease. [ ] [ ] [ ] although control of the outbreak was achieved by culling millions of birds in the hong kong markets, this episode demonstrated that the capability for an effective global response to emerging influenza threats was poor because of technical, legislative, and infrastructural limitations. a disturbing finding that emerged from this event was that the scientific community was unable to produce an effective vaccine even after several years. the inactivated human influenza vaccines in use today are derived from essentially modified viruses. by exploiting the segmented nature of the influenza a genome, vaccine manufacturers and the laboratories of the who influenza network have produced a reassortant virus carrying the circulating virus's gene segments that encode haemagglutinin and neuraminidase, the major targets of neutralising antibodies. the remaining six-gene segments are supplied from pr , a laboratoryadapted avirulent h n strain. the resulting reassortant virus has the antigenic properties of the circulating strain and the safety and high-yield properties of pr . the first batch of inactivated material against the h n virus was not ready for clinical trial until months after the second case of human infection arose, and even today the effectiveness of vaccine against this virus has not been proven. a key reason for this delay in the production of an h n -specific vaccine was the nature of the virus itself. the h n virus is highly pathogenic in human beings and poultry. the agent must be handled only under conditions of at least biosafety level (bsl ), and it can kill fertilised chicken eggs, the standard medium for the reassortment and responsiveness to a pandemic alert: use of reverse genetics for rapid development of influenza vaccines propagation of influenza virus before its inactivation and formulation for use in vaccines. these same traits are present in the h n virus. the pathogenic nature of these h n viruses is linked to the presence of additional basic residues in haemagglutinin at the site of cleavage, a step required for haemagglutinin activation and, thus, for virus entry into cells. [ ] [ ] [ ] to overcome the high pathogenicity of the virus, polybasic aminoacids have to be eliminated. a rapid, reproducible system to achieve these modifications-ie, plasmid-based reverse genetics-has been developed only in the past - years [ ] [ ] [ ] the potential benefits of reverse genetics for the generation and attenuation of vaccine candidates against highly pathogenic and low pathogenic influenza viruses are enormous. [ ] [ ] [ ] however, the host specificity of the rna polymerase i promoter used in the influenza reverse-genetics systems and the required use of an approved cell line limits the practical options for the system's use in the manufacture of human vaccines. the vaccine-candidate reference virus stock described in this report has been produced entirely on a cell substrate licensed for the manufacture of human vaccine, and as such, is-to our knowledge-the first reverse genetically derived influenza vaccine suitable for testing in clinical trials. we describe the construction of a vaccine reference virus in good manufacturing practice (gmp)-grade facilities in less than weeks from the time of virus isolation. our findings highlight the speed with which new technologies can be implemented in response to influenza pandemic alerts. we obtained who-approved vero cells (who-vero, x , p ) from the american type culture collection (manassas, virginia, usa). passage- cells (five passages since their removal from a working cell bank) were used for the rescue of the vaccine-candidate virus. the plasmids containing the genes from pr have been described elsewhere. virus propagation, rna extraction, pcr amplification, and haemagglutinin and neuraminidase gene cloning we obtained a/hong kong/ / (h n ) that had been passaged in eggs from the who influenza network. the virus was isolated and propagated in -day-old embryonated chicken eggs. total rna was extracted from infected allantoic fluid with use of the rneasy kit (qiagen, valencia, ca, usa) in accordance with manufacturer's instructions. reverse transcription was carried out with the uni primer ( Ј-agca aaagcagg- Ј) and amv reverse transcriptase (roche, indiana biochemicals indianapolis, usa). the removal of the connecting peptide of the haemagglutinin was done with use of pcr with the following primer sets: ( ) bm-ha- ( Ј-tattcgtctcagggagcaa aagcagggg- Ј) and ⌬r ( Ј-taatcgtc tcgtttcaatttgagggctatttctgagcc- Ј); and ( ) ⌬f ( Ј-taatcgtctctgaaa ctagaggattatttggagctatagc- Ј) and bm-ns- r ( Ј-atatcgtctcgtattagtag aaacaagggtgtttt- Ј). we amplified the neuraminidase gene of a/hong kong/ / using the primer pair ba-na- ( Ј-tattggtctc agggagcaaaagcaggagt- Ј) and ba-na- r ( Ј-atatggtctcgtattagtagaaacaag gagtttttt- Ј). pcr products were purified and cloned into the vector phw as described previously. the rescue of infectious virus from cloned cdna was done under gmp conditions. vero cells were grown to % confluency in a cm flask, trypsinised (with trypsin-versene), and resuspended in ml of opti-mem i (invitrogen, carlsbad ca, usa). to ml of cell suspension we added ml of fresh opti-mem i; then, we added ml of this diluted suspension to each well of a six-well tissue culture plate (about ϫ cells per well). the plates were incubated at °c overnight. the next day, g of each plasmid and l of transit lt- transfection reagent (panvera, madison, wi, usa) were added to opti-mem i to a final volume of l and the mixture incubated at room temperature for min. after incubation, the medium was removed from one well of the six-well plate, l of opti-mem i added to the transfection mix, and this mixture added dropwise to the cells. h later, the dna-transfection mixture was replaced by opti-mem i. h after transfection, ml of opti-mem i that contained g/ml l-(tosylamido- phenyl) ethyl chloromethyl ketone (tpck)-treated trypsin (worthington biochemicals, lakewood, nj, usa) was added to the cells. about h after the addition of tpck-trypsin, the culture supernatants were harvested and clarified by low-speed centrifugation; we then injected l of the clarified supernatant into the allantoic cavity of individual -day-old pathogen-free embryonated research grade eggs (charles river spafas, north franklin, ct, usa). ten -week-old chickens received intravenous injections of · ml diluted virus (dilution ratio, / ). we monitored chickens for signs of disease for days using the intravenous pathogenicity index, approved by the office of international epizooites (oie). additionally, we took tracheal and cloacal swabs (in ml of media) days and days after infection, and we did assays for the presence of virus by injection of · ml into all of three -day-old embryonated chicken eggs. haemagglutination activity in the allantoic fluid of these eggs was assessed after incubation at °c for days. pathogenicity testing in ferrets we tested pathogenicity of the vaccine in five young adult male ferrets (marshall's farms, north rose, ny, usa) aged - months (weight about · kg) that were shown by haemagglutination inhibition assays to be seronegative for currently circulating human influenza a viruses (h n , h n ) and h n viruses. we anaesthetised the ferrets with inhaled isoflurane, and they were then infected intranasally with % egg infectious dose (eid )/ml of vaccine reassortant virus or wildtype virus. we monitored the ferrets once per day for signs of sneezing, inappetence, and inactivity, and we recorded rectal temperatures and bodyweights. , , and days after infection, the ferrets were anaesthetised with ketamine ( mg/kg), and we collected nasal washes using ml of sterile phosphatebuffered saline (pbs) containing antibiotics. we measured titres of virus in these washes with eid assays. to further assess the pathogenicity of the viruses, we collected tissue samples from lungs, brain, olfactory bulb, spleen, and intestine for virus isolation and histopathological analysis at the time of death or in the case of three ferrets, after euthanasia at day after infection. the tissues were fixed in % neutral buffer formalin, processed and embedded in paraffin, sectioned at g, stained with haematoxylin and eosin and examined by light microscopy in a blinded fashion. to test the stability of the vaccine virus on propagation, we made consecutive passages of the virus in embryonated chicken eggs. a - dilution of the virus was made in pbs, and · ml of the solution was injected into the allantoic cavities of all of four -day-old embryonated chicken eggs. eggs were incubated at ºc for · - days. after incubation, each egg was candled to determine embryo viability before chilling at ºc. we harvested ml of allantoic fluid from each egg harvested, and samples were pooled together, tested for haemagglutination activity, and then reinjected into another four eggs. the sponsor had no role in study design, in the collection, analysis, and interpretation of data, in the writing of the report or decision to submit this manuscript for publication. the first challenge we faced in producing a vaccine against a/hong kong/ / (h n ) was to attenuate the virus in preparation for mass production. previous experiences have shown that removal of the basic aminoacids at the haemagglutinin cleavage site substantially attenuates pathogenic influenza viruses. [ ] [ ] [ ] using a pcr-based mutagenesis approach, we replaced the cleavage site encoded by the haemagglutinin gene of a/hong kong/ / (h n ) with that of the avirulent a/teal/hong kong/w / (h n ) (figure ); this modified haemagglutinin gene and the neuraminidase gene of a/hong kong/ / (h n ) were cloned individually into the vector phw . the two resulting plasmids and the six plasmids encoding the remaining proteins of pr were transfected into whoapproved vero cells under gmp conditions to rescue the vaccine seed virus, ⌬ /pr . - h after transfection, isolated areas of cytopathic effect could be seen on the vero monolayers. although addition of further g aliquots of tpck-treated trypsin every h led to a proportional increase in the cytopathic effect, it was not required for successful virus rescue. the candidate vaccine strain grew to high titres on subsequent amplification in eggs (haemagglutination titres of - ) and did not cause embryo death. the vaccine seed virus was unable to form plaques on madin-darby canine kidney (mdck) cells in the absence of trypsin, a trait consistent with that of influenza viruses that lack the polybasic cleavage site, and was antigenically indistinguishable from the parental h n virus in haemagglutination inhibition assays. the rescued virus was fully sequenced and was identical to the plasmids used in its creation. to assess the pathogenicity of the h n vaccine seed virus, we compared the properties of this virus with those of the wildtype a/hong kong/ / (h n ) in ferrets and in chickens. by stark contrast with the wildtype virus, which was lethal to all chickens within h of infection, intravenous administration of a / dilution of ⌬ /pr did not result in any signs of infection in chickens, and we were unable to detect any virus in swabs of cloacae or tracheae from inoculated birds. compared with a/hong kong/ / (h n ), ⌬ /pr was attenuated in ferrets that had been inoculated intranasally with eid of virus. ferrets infected with a/hong kong/ / had inappetence and weight loss (figure ), with one infected animal dying days after infection and a second killed days after infection because of hind-limb paralysis. infection in these animals was characterised by viral shedding until days after infection and replication of virus in the lower respiratory tract and olfactory bulb (as determined by virus isolation). in the a/hong kong/ / infected animals, there was a mild mononuclear cell infiltrate in the meninges and tracheal submucosal mucous glands and an extensive bronchopneumonia. the pneumatic infiltrate progressed in severity from the bronchi to the pleura. the bronchi and bronchioles contained sloughed necrotic epithelial cells, numerous mononuclear cells, and a few neutrophils. the alveoli were consolidated with inflammatory cells and fibrin (figure ). by contrast, those ferrets infected with ⌬ /pr did not lose weight (figure ) and seemed to remain healthy during the study ( days) ( figure ) . virus was detected in the nasal washes of these animals at days but not days after infection, and virus was recovered from the upper respiratory tract only. by light microscopy, the meninges and trachea of the ⌬ /pr infected ferrets did not have an inflammatory infiltrate and only a few neutrophils were noted occasionally in pulmonary bronchi. our results clearly show that ⌬ /pr was attenuated. in view of our findings, this virus can be safely handled with standard precautions in bsl containment facilities. because the mechanisms and requirements for the accumulation of basic aminoacids at the haemagglutinin cleavage site are not entirely understood, we wanted to confirm that the altered cleavage site remained stable on multiple passages in embryonated chicken eggs. such passaging in eggs would occur in transition and amplification of the reference virus to vaccine stock. the rescued virus was stable on continued serial passage in embryonated eggs, and we did not detect any change in nucleotide sequence of the haemagglutinin cleavage site after passages. there was no evidence of changing pathogenicity of the virus and we noted only one dead embryo at passage . no haemagglutination activity was evident in this egg and no embryo death was seen in passage , which strongly suggests that the death was not related to virus replication. haemagglutination titres at each passage ranged from to with no apparent trend of increasing or decreasing titres in subsequent passages. the rapid response in terms of potential vaccine reference virus production to the h n outbreak differs strikingly from the response to the episode. this difference is attributable to the new scientific technology available in and, just as importantly, to the infrastructure for virus surveillance in hong kong developed since . the first case of h n influenza in hong kong was in may, ; yet several months elapsed before this virus was finally characterised as an h n virus. in , the causative agent was identified only hours after admission of the patients to the hospital. the increased awareness, surveillance, and availability of reagents to identify influenza viruses of all subtypes bode well for the rapid identification of viruses that arise from future interspecies transfer events and for the coordination of international vaccine development by who. the timely distribution of candidate viruses is a very important step in the development of vaccines for pandemic emergencies. despite the heightened security and documentation requirements for shipping and receiving potential bioterrorism agents, the h n and sars outbreaks have shown that in true emergencies, global distribution is feasible. although it is pertinent to prepare for future pandemics by stockpiling potential vaccine strains, the h n situation in -and the ongoing h n outbreaks throughout asia in (http://www.who.int)-have highlighted the fact that some of the focus of pandemic planning must go into the implementation of technology to rapidly produce vaccines from field isolates. although viruses similar to a/hong kong/ / (h n ) had been circulating in bird populations, these viruses were antigenically distinct, despite high genetic similarities (guan y and peiris js, unpublished data). that the aminoacid differences are on the globular head of haemagglutinin and seem to be responsible for much of the antigenic difference means that even a vaccine previously prepared from genetically similar precursor viruses might not provide adequate protection. we may well be faced with potential pandemic situations in the future and the rapid production of a matched vaccine will be needed-a point again highlighted by h n outbreaks in . although the reference virus described in this report was prepared from a virus isolated in a similar geographic region and only a year earlier, it shares only limited antigenic cross-reactivity to the h n viruses. hyperimmune sheep serum samples produced against the purified haemagglutinin of ⌬ /pr has at least a six-fold reduced haemagglutination inhibitory activity against a/vietnam/ / as compared with a/hong kong/ / . as our findings show, we have the technical capabilities to respond rapidly to outbreaks with a safe and stable reference virus, but there is still much to be accomplished before such viruses can be fully used in pandemic and interpandemic influenza vaccine production. the use of reverse genetics introduces a number of new processes into influenza vaccine manufacture that are not encountered with standard reassortment methods. one of the most obvious is the need for cultured cells. although both vero and mdck , cells are in development as substrates for the growth of influenza vaccine, there are additional requirements for the use of cells in reverse genetics. unfortunately, the number of suitable cell lines is very small. in addition to the regulatory requirements, the choice of cell is also limited by the technology. the plasmid based reverse-genetics systems necessitates the use of cells from primate origin. the vero cell line is probably the only option currently able to meet both regulatory and technical demands. we have shown that vero cells can be used to successfully rescue h n , h n , h n , and h n viruses on the pr backbone using the -plasmid system. others have demonstrated the suitability of vero cells for alternative influenza virus reverse-genetics systems. although cultures of vero cells are easily obtained, only cells from fully tested and licensed cell banks are likely to be acceptable for vaccine manufacture. this issue must be acknowledged and access to such cells must be incorporated as part of future pandemic plans. that future threats of influenza pandemics will be addressed by the use of the technology described in this report seems inevitable. despite the presence of low pathogenic surrogate strains, the recent human death from influenza-like illness caused by highly pathogenic h n virus in the netherlands reinforces the fact that future outbreaks will probably occur in which this reversegenetics technology provides the logical-and, possibly, the only-way to respond rapidly and effectively. although our response to the outbreak of h n influenza in has shown that current scientific capabilities are sufficient to respond to the threat, there are still legal and infrastructural barriers to be overcome. these barriers include licensing and intellectual property issues surrounding what is, essentially, a genetically modified organism. yet, these difficulties are not insurmountable and pandemic scares such as the and ongoing h n outbreaks are forcing commercial and regulatory parties to address these issues with some urgency. with the development of the h n vaccine reference virus, and ongoing attempts to create the same for the virus, the challenge in responding to a threat of an influenza pandemic must now be supported by the largescale manufacture of the vaccine and by clinical trials of a new vaccine manipulated by reverse genetics. r j webby, d r perez, j s coleman, j h knight, e i tuomanen, r g webster designed the study; r j webby did much of the construction of the vaccine seed virus; d r perez developed and constructed plasmid templates; y guan and j s peiris characterised and isolated the initial h n virus; j e rehg participated in the design and analysis of animal safety testing of the candidate h n vaccine seed virus; e a govorkova participated in the safety testing of the candidate h n vaccine seed virus; l r mcclain-moss participated in the preparation of gmp documentation of the process and was involved in the reconstitution of the vaccine seed virus. a pandemic warning? characterization of an avian influenza a (h n ) virus isolated from a child with a fatal respiratory illness characterization of avian h n influenza viruses from poultry in hong kong interspecies transmission of influenza viruses: h n virus and a hong kong sar perspective future influenza vaccines and the use of genetic recombinants developing vaccines against pandemic influenza the structure of the hemagglutinin, a determinant for the pathogenicity of influenza viruses proteolytic cleavage of influenza virus hemagglutinins: primary structure of the connecting peptide between ha and ha determines proteolytic cleavability and pathogenicity of avian influenza viruses molecular analyses of the hemagglutinin genes of h influenza viruses: origin of a virulent turkey strain rescue of influenza a virus from recombinant dna a dna transfection system for generation of influenza a virus from eight plasmids generation of influenza a viruses entirely from cloned cdnas eight-plasmid system for rapid generation of influenza virus vaccines plasmid-only rescue of influenza a virus vaccine candidates evaluation of a genetically modified reassortant h n influenza a virus vaccine candidate generated by plasmid-based reverse genetics recombinant influenza a virus vaccines for the pathogenic human a/hong kong/ (h n ) viruses preparation of a standardized, efficacious agricultural h n vaccine by reverse genetics development of a vero cellderived influenza whole virus vaccine influvac: a safe madin darby canine kidney (mdck) cell culturebased influenza vaccine safety and immunogenicity of a trivalent, inactivated, mammalian cell culture-derived influenza vaccine in healthy adults, seniors, and children generation of high-yielding influenza a viruses in african green monkey kidney (vero) cells by reverse genetics avian influenza a virus (h n ) associated with human conjunctivitis and a fatal case of acute respiratory distress syndrome pandemic influenza and the global vaccine supply we thank todd hatchette, katherine sturm-ramirez, and scott krauss for expert advice; ashley baker, christie johnson, yolanda sims, patrick seiler, jennifer humberd, and kelly jones for excellent technical assistance; julia hurwitz for access to the vero-cell banks. editorial assistance was provided by julia cay jones. these studies were supported by grant ai from the national institute of allergy and infectious disease, by cancer center support (core) grant ca from the national institutes of health, and by the american lebanese syrian associated charities (alsac). none declared. the corresponding author has had full access to all the data in the study and has had the final responsibility for the decision to submit this manuscript for publication. key: cord- -azqjvxtu authors: kwong, kim-hung; lai, poh-chin title: spatial components in disease modelling date: journal: computational science and its applications - iccsa doi: . / - - - - _ sha: doc_id: cord_uid: azqjvxtu modelling of infectious diseases could help gain further understanding of their diffusion processes that provide knowledge on the detection of epidemics and decision making for future infection control measures. conventional disease transmission models are inadequate in considering the diverse nature of a society and its location-specific factors. a new approach incorporating stochastic and spatial factors is necessary to better reflect the situation. however, research on risk factors in disease diffusion is limited in numbers. this paper mapped the different phases of spatial diffusion of sars in hong kong to explore the underlying spatial factors that may have interfered and contributed to the transmission patterns of sars. results of the current study provide important bases to inform relevant environmental attributes that could potentially improve the spatial modelling of an infectious disease. acute respiratory infections were transmitted through aerosol transmission of respiratory secretions from coughing and sneezing. conditions such as overcrowding and poor personal hygiene tend to facilitate the transmission of respiratory diseases [ ] . education about personal hygiene and simple intervention measures such as washing hands can help to minimize disease incidence [ ] [ ] [ ] . a model of sars transmission by riley et al. [ ] suggested that the spread of sars is highly geographical and localized such that a complete ban on travel between local districts could expect to reduce the transmission rate by %. therefore, a closer examination of the sars occurrences in space and time could provide a better understanding of the spatial diffusion patterns and possible environmental factors contributing to such patterns. besides, an enhanced understanding of the spatial spread could extend knowledge on the detection of epidemics and help advice infection control and intervention measures. it is also known that conventional disease transmission models are inadequate in considering the diverse nature of a society and its location-specific factors [ ] [ ] [ ] . this research made an attempt to map different phases of the spatial diffusion of sars in hong kong to identify the underlying spatial factors attributing to its transmission patterns. results from the study offer useful guidance about the selection of environmental risk factors for inclusion in the spatial modelling of an infectious disease. various efforts have been made to simulate the outbreaks of sars using mathematical methods [ ] [ ][ ] [ ] [ ] . many of the models were based on the deterministic approach, such as seir, which incorporates the susceptible population (s), exposed/infected population (e), infectious population (i), and the recovered (immune) / removed (death) population (r) [ ] [ ] [ ] . seir models explain the diffusion of a disease among the four population groups. seir and other related models often require little data, are relatively easy to set up, and can generally simulate infectious disease dynamics among the population [ ] . such models, however, do not consider dynamic elements transpired by population mobility and social mixing; both of which are largely influenced by socioeconomic and environmental factors. small and tse [ ] explained that these conventional models have an underlying assumption that each member of the entire population has an equal chance of being infected. such an assumption ignores the complex socio-demographic and environmental factors afflicting the transmission course of a disease among various subgroups (e.g., the wealthy, middle class, and the disadvantaged). a typical mathematical model suggests that a disease epidemic would ultimately infect the entire population [ ] [ ] . the reality is that certain communities may be affected less by an epidemic. for example, sars cases seemed to cluster in several disease "hot spots" in hong kong [ ] . jefferson et al. [ ] also reported that simple physical interruptions, such as systematic education on personal hygiene and isolation of infected patients, were effective in preventing the spread of respiratory diseases. hence, dye and gay [ ] concluded that the next generation of disease models should include spatial processes and stochastic factors to tender a better solution to the problem. the geographic information system (gis) technology is well suited for analysing epidemiological data and characterising the spatio-temporal patterns of epidemics [ ] [ ] . epidemiological data often have a spatial context, such as the residential or work addresses of patients and the spatial patterns associated with a disease. efforts have been made to incorporate the dimension of space into disease simulation. sattenspiel and dietz [ ] , for example, created an epidemic model that accounts for geographic mobility of the population in different regions. despite the assumptions of a single trip and a static population, their model was regarded superior to the conventional seir models because it considered in calculating the transmission risk both epidemic and behavioural processes, as well as environmental factors. small and tse [ ] modelled the spread of sars using a small world model to simulate its spatial diffusion using the network structure. however, their model assumed that the environmental factors and population composition within the small world were homogenous. meng et al. [ ] tried to employ spatial analysis to investigate and understand factors affecting the spatial transmission process of sars in beijing. they identified population density as a significant factor for the spatial diffusion in this case. however, "population density" alone may not reveal overcrowding conditions at the micro-level, especially in places like hong kong where a mixed land use is not uncommon and where non populated country parks are adjacent to urbanized areas. riley [ ] documented four kinds of models (patch, distance, group and network) for the transmission of infectious diseases. he applied these models to simulate various disease outbreaks in the uk and found the group model to be the most suitable for human-to-human transmission of influenza. watkins et al. [ ] also tried to model infectious disease outbreaks using a gis to incorporate traditional seir models in their simulations. their examples also showed that the establishment of a spatial model for contagious diseases (such as sars) was essential in understanding how the disease spread through time and space. furthermore, hsieh et al. [ ] highlighted the importance of creating distinct and explicit spatial models for the understanding of the specific patterns of transmission of sars in each region or country. a new approach seems necessary to address the location-specific as well as environmental and socio-demographic risk factors for communicable diseases. however, only a limited number of studies (such as lau et al. [ ] ) has identified some risk factors for the sars transmission in hong kong. this study is an attempt to isolate risk (or stochastic) factors to model the transmission dynamics of a disease in space. the study is based on data collected for the sars outbreak of hong kong. our approach attempts to extract features in space that contribute towards social mixing. we argue that social mixing is a function of transport infrastructures and can also be reflected through certain social-economic indicators. the study area covers the whole territory of hong kong and the data include , confirmed cases of sars occurring between february and june . we divided the sars epidemic into four phases and by spatial units of districts to explore its spread across space and time. our research hypotheses are as follows: ) h : there is no relationship between disease spread and transport infrastructure h a : disease spread follows the pattern of transport infrastructure ) h : there is no relationship between disease incidence and various socioeconomic characteristics (refer to section . for such characteristics) h a : disease incidence correlates with various socio-economic characteristics we obtained the sars data from the hong kong hospital authority. a patient record includes an identifier, residential address, hospital admission date, onset date of symptoms, hospital admitted to, as well as health conditions at admission. personal particulars of individuals were stripped and their residential addresses were replaced with geo-coordinates, with no information about flat numbers and building names, to ensure data privacy. we employed the geographical data (b for the whole of hong kong) acquired from the lands department the hong kong special administrative region (hksar) government for spatial analysis and spatial modelling of sars. the ar-cgis . geographic information system software was used as a platform for data input and manipulation. maps were created to reveal the locations of sars cases. aggregation of cases to the districts level was also made to extract potentially risky districts during various phases of the sars epidemic in . demographic and census data of the general population were abstracted from the population census (in street block or small tertiary planning unit levels (stpu)) compiled by the census and statistics department of the hksar government [ ] . we incorporated such data to investigate possible socio-economic factors that might have affected the spatial distribution of sars. as the human-to-human transmission of sars is through close contacts, variations in the socio-economic constructs by different spatial units might influence its spatial distributional patterns [ ] . grids of m x m were created. sars data and census data were spatially joined to the grid level for analysis. we examined the relationship between the sars incidence and the following socio-economic characteristics as stipulated in hypothesis above. a) percentage of population with tertiary level education b) percentage of population aged under c) percentage of population aged over d) non-working population e) median household income f) median personal income g) average number of rooms per household h) net residential density we followed the irish government's guidelines [ ] when defining net residential density because there is no such guideline in hong kong. non populated areas (such as country parks) were excluded in our analysis. the reason for not using population density directly is because many areas in hong kong are of the mixed land use type (e.g. inner city areas of kowloon and northern hong kong island where residential areas are mixed with commercial / retail uses). moreover, some residential areas are also situated adjacent large plots of non populated country parks (please refer to figure for such situations in kowloon and the hong kong island) which are often included in the total area of specific administrative districts or planning units. population density in these areas will therefore be under-represented and not reflecting truly how crowded a place is. statistical methods, including pearson's correlation co-efficient, were employed to determine the significance of various environmental and demographic factors contributing to the spatio-temporal transmission of sars. figures c and d) when sars became widespread throughout the whole territory of hong kong. an interesting point to note is that the north-south linear spread pattern in the early stages of the epidemic, as illustrated in figures a and b , corresponds to the east rail line which is a heavily used mass transit railway connecting kowloon and the northeast new territories (figure ). it appears that transport might have an essential role in facilitating disease spread. a previous study of sars transmission in china also confirmed that modern public transport has a vital part in spreading contagious diseases like sars [ ] . the study reported that sars had two major hotspots in guangdong and provinces near beijing. intersections of national highway, in particular, were a high risk factor for the spatial diffusion of sars. while an appropriate test of significance is not available, the visual evidence derived of the sars data in our study does suggest that the null hypothesis is not substantiated. medical facilities could be another important contributor to the diffusion of sars. more than workers in room a of the prince of wales hospital (pwh), where the first sars patient was admitted, were infected with sars in early march [ ] . figure shows that the sha tin district, where the pwh is located, was most severely affected by sars during the first two phases of the epidemic in . confirmed cases in sha tin for phases and accounted for . % ( out of ) and . % ( out of ) of total sars cases in hong kong. the close proximity of residents in sha tin to the pwh, which is the primary source of nosocomial infection, meant that they were at a higher risk of contracting sars in the early phases of the epidemic. this is in line with lau et al. [ ] [ ] who suggested that more than a quarter of the sars patients in hong kong in were health care workers and hospital visit was a risk factor for contracting sars. similar conclusions were made by meng et al. [ ] that medical care resources affected the spatial contagion of sars in beijing. socio-economic factors found statistically significant against sars incidence included the following: c) percentage of population aged over , g) average number of rooms per household, and h) net residential density ( table ). all other variables did not exhibit a statistically significant relationship with the occurrence of sars. table also shows that net residential density had a significant positive correlation with the occurrence of sars. figure is a map of sars cases plotted over residential density in the city centres of hong kong (kowloon and the hong kong island). it illustrates that disease cases were concentrated mostly in areas of high residential densities. areas with lower residential densities in figure (such as -kowloon tong, -southern district, and -mid-levels) had fewer cases throughout the epidemic as shown in figure . this observation matches that of a study by meng et al. [ ] who demonstrated that population density was an important factor affecting the spatial diffusion of sars in beijing. the average number of rooms per household was also found to have a statistically significant negative correlation with sars because this factor is likely associated with residential density. people must share a room with their family members given fewer rooms per household in places with a high residential density. the percent of elderly population (over years old) was statistically significant at the less stringent % instead of % confidence level. while the elderly have been found more susceptible to various types of infectious diseases including sars [ ] [ ] [ ] , their less active social role could have ameliorated the chance of contracting a contagious disease. the results indicate that the null hypothesis can be rejected for socio-economic characteristics of net residential density, average number of rooms per household, and elderly population. in other words, these three characteristics exhibited statistically significant correlation with the occurrence of sars in hong kong. these socialeconomic factors could be used to explain the transmission patterns of the sars epidemic. new and re-emerging of infectious diseases post challenges and threats to the health systems of many countries. while medical treatment of patients with contagious diseases has been top priority in curtailing epidemics, surveillance and early warning are equally important [ ] . deterministic and mathematical models of communicable diseases are not adequate as a decision tool because they fall short of providing information about an epidemic form the spatial perspective. moreover, these models are not able to account for stochastic factors that influence the spatial dispersion of a disease outbreak. previous studies of the diffusion of sars in hong kong and beijing have shown evidence of geographical concentrations of sars cases [ ] [ ] . further efforts to incorporate stochastic events in modelling the spatio-temporal transmission of an infectious disease such as sars are therefore necessary. gis provides an integrated platform for the examination of spatio-temporal diffusion of a disease. this research studies sars diffusion in space and various temporal phases of the epidemic using the gis technology. we have identified some environmental and demographic factors deemed important in affecting the spatial transmission of sars. obtaining results that are in line with similar studies in other places, our study concluded that environmental factors (in this case, transport infrastructure and hospital locations) played a key role in shaping the diffusion pattern of sars. certain socio-economic factors (i.e., average number of rooms per household, percentage of elderly population, and net residential density) were found to correlate positively with the occurrence of sars in hong kong, indicating their potential influence in the disease transmission. the research findings set the groundwork for the construction of a combination of stochastic and geographical-based models to simulate the transmission patterns of an infectious disease in space and time. previous studies have documented deficiencies of deterministic models in addressing spatial differences and severity of an epidemic. this research mapped different development phases of the sars epidemic in hong kong and employed the pearson's correlation to isolate environmental factors and socio-economic factors of significant pertinence to the disease. the results are useful in paving the ways forward to study disease transmission in space and time. future studies may take heed of our research findings to construct spatial models of disease transmission. the risk factors identified in this study could be incorporated in the modelling process to improve model predictability. communicable diseases in complex emergencies: impact and challenges probable secondary infections in households of sars patients in hong kong sars transmission, risk factors, and prevention in hong kong severe acute respiratory syndrome (sars): status of the outbreak and lessons for the immediate future transmission dynamics of the etiological agents of sars in hong kong: impact of public health interventions the effects of population heterogeneity on disease invasion a structured epidemic model incorporating geographic mobility among regions small world and scale free model of transmission of sars modeling the sars epidemic transmission dynamics and control of severe acute respiratory syndrome a double epidemic model for the sars propagation severe acute respiratory syndrome (sars) in asia: a medical geographic perspective deterministic modeling of infectious diseases: theory and methods clustering model for transmission of the sars virus: application to epidemic control and risk assessment understanding the spatial clustering of severe acute respiratory syndrome (sars) in hong kong physical interventions to interrupt or reduce the spread of respiratory viruses: systematic review large-scale spatial-transmission models of infectious disease understanding the spatial diffusion process of severe acute respiratory syndrome in beijing using gis to create synthetic disease outbreak sars outbreak government of ireland: residential density -guidelines for planning authorities geographical spread of sars in mainland china over staff in prince of wales hospital were infected hong kong economic times the sars (severe acute respiratory syndrome) pandemic in hong kong: effects on the subjective wellbeing of elderly and younger people new respiratory viruses of humans inhibition of infection caused by severe acute respiratory syndromeassociated coronavirus by equine neutralizing antibody in aged mice key: cord- - ic p u authors: chong, ka chun; goggins, william; zee, benny chung ying; wang, maggie haitian title: identifying meteorological drivers for the seasonal variations of influenza infections in a subtropical city — hong kong date: - - journal: int j environ res public health doi: . /ijerph sha: doc_id: cord_uid: ic p u compared with temperate areas, the understanding of seasonal variations of influenza infections is lacking in subtropical and tropical regions. insufficient information about viral activity increases the difficulty of forecasting the disease burden and thus hampers official preparation efforts. here we identified potential meteorological factors that drove the seasonal variations in influenza infections in a subtropical city, hong kong. we fitted the meteorological data and influenza mortality data from to in a susceptible-infected-recovered model. from the results, air temperature was a common significant driver of seasonal patterns and cold temperature was associated with an increase in transmission intensity for most of the influenza epidemics. except , the fitted models with significant meteorological factors could account for more than % of the variance in additional to the null model. rainfall was also found to be a significant driver of seasonal influenza, although results were less robust. the identified meteorological indicators could alert officials to take appropriate control measures for influenza epidemics, such as enhancing vaccination activities before cold seasons. further studies are required to fully justify the associations. hong kong, a city located in the south china sea, has a humid subtropical climate with winter (december-february) temperatures that usually range from to °c, warm springs and autumns, and hot summers (june-september) with daytime temperatures in the low to mid s and nighttime temperatures in the high s. in temperate regions, influenza has a clear seasonal pattern with an exponential increase in infections in the winter, which is followed by a fade-out period of a few months. in subtropical regions, there is no sufficient understanding of the seasonal pattern of influenza and its relationship with meteorological factors. the number of epidemic peaks can differ across various subtropical regions, with the peaks usually occurring at different periods within a year [ ] [ ] [ ] . according to the world health organization (who), influenza epidemics result in to thousand deaths worldwide annually [ ] . in hong kong, the influenza hospitalization rate and the pneumonia and influenza (p&i) associated mortality were estimated to be and . per , person-years respectively [ , ] . hong kong was also regarded as an epicenter of pandemic influenza in southeast asia. insufficient information about viral activity creates difficulties in forecasting the disease burden and thus hampers official preparation efforts. despite numerous researches that have discovered meteorological factors associated with various activities of influenza, little is known about the drivers of transmission or its seasonal variations for different climates. a small variation in influenza transmission could result in amplification and damping of infection oscillations over time and thus sustain a seasonal pattern [ ] . possible drivers of influenza transmission include meteorological variations [ ] , susceptible numbers [ , ] , and social mixing [ ] . recently, shaman et al. employed a mathematical model to demonstrate that the seasonal pattern of influenza in the united states could be drawn based on the process of simulations driven by the absolute humidity [ ] . this finding motivated a further investigation of potential meteorological drivers for subtropical climates. in this study, meteorological determinants that could drive the seasonal variations of influenza in hong kong were investigated by a mathematical model. we hypothesized that the transmission rates in a population-level model, as well as the infection oscillations of seasonal influenzas, are affected by meteorological factors. identification of the drivers will help to improve the understanding of influenza transmission and to alert officials to implement preemptive control measures for seasonal influenza. data on deaths from p&i from to in hong kong were obtained from the hong kong census and statistics department (figure ). the mid-year population (nyear) from to was collected from the hong kong census and statistics department [ ] . we separated each wave of p&i deaths by year from week to week of the following year. as the wave of was stopped earlier, it would start from week until week of . the wave is from week to week of , in order to prevent the overlap of cases after the outbreak of the h n pandemic. the weekly average of meteorological parameters: air temperature, relative humidity, total rainfall, total solar radiation, wind direction, and wind speed from to were collected from the hong kong observatory. the time series of the data is shown in figure . actual vapor pressure (e) was calculated as a metric for absolute humidity by the teten's formula [ , ] : where es(ta) is the saturation vapor pressure (hpa), rh is the relative humidity (%), and ta is the air temperature (°c). the es was calculated as follows: ta ta ta e s . . exp . ) ( the saturation vapor pressure in the teten's formula can also be obtained by the integration of clausius-clapeyron equation and is acceptable for most meteorological purposes [ , ] . as the wind data was in the polar coordinate scale, we develop wind velocity variables in the cartesian scale that encompasses wind direction and wind speed, thus preventing the problem of northerly bearings being split at true north. two parameters of wind velocity (east-to-west and north-to-south) were used as metrics for wind data in the analysis. we extended the susceptible-infected-recovered (sir) model from chowell et al. [ ] to describe the dynamic system of seasonal influenza. in this model, a population is comprised of four compartments: susceptible (s(t)); infectious (i(t)); recovered (r(t)); and dead (d(t)), at each time point t. the sir model consists of four differential equations that describes the rates of subject movements for each of the time steps. we assumed homogeneous mixing, meaning that each individual has the same chance of contacting another individual within the population. in the compartmental model, once susceptible individuals in compartment s(t) get infected, they will move to compartment i(t) and stay there for the infectious period. when the infectious period is over, the individuals in compartment i(t) will recover and move to compartment r(t) or will die and move to compartment d(t). in this model, the time-varying transmission rate per individual is βt and the force of infection for time t is βti. we denote s(t), i(t), r(t), and d(t) as s, i, r, and d as the subpopulations in each compartment for time t. the deterministic system of equations are as follows: we assumed that the length of the generation interval (gi) follows an exponential distribution with mean = /(γ + δ). suppose cfp is the average case fatality proportion, the mortality rate is δ = (cfp/( − cfp)) and δi is the influenza deaths generated by the differential equations. to make the model coefficients more comparable to each other, meteorological variables are transformed by subtracting the mean and divided by the standard deviation (sd) over their sampling period. let xt i be a particular i-th independent variable (e.g., air temperature at time t), the transformed form would be: where i x is the sample mean and σ i x is the sd for the sampling period. the meteorological effects are related to βt using the following linear component: where n is the number of independent variables. the model will determine the significant drivers to the influenza transmission rate. in the differential equations, we assumed a -day length of gi [ ] and a . % cfp [ ] . to account for the variation of partial immunity to the seasonal influenza, we followed previously published procedures [ , ] . the initial number of susceptibles in equation ( ) was calculated by where d( ) was set to be the number of p&i deaths in the first epidemic week. thus, the initial number of recovered individuals can be calculated as rather than fixing a value, mid-year population (nyear) was used for each wave, so as to reduce the impact from natural mortality and birth. the weekly p&i death data was fitted to model generated deaths (i.e., δi) and the meteorological time series data consisted of the variables (xt i ) for each epidemic wave. parameters i( ), b , b ,…,bn could be estimated by least-squares fitting to the data. as weekly data was used, t was measured in weeks. statistically significant meteorological parameters (p-value of bi < . ) were declared as potential drivers to seasonal variations of influenza. a stepwise variable selection approach was adopted and the best fitted model was chosen as the one with all statistically significant variables and the lowest akaike information criterion (aic) [ ] : where m is the number of data points, p is the total number of parameters, and sse is the sum of square errors. instead of sampling, all possible parameter combinations were assessed by a grid search. as the absolute humidity was derived from the temperature and relative humidity, they could not be included in the same variable pool during the stepwise variable selection, due to the co-linearity problem. the variable set with temperature, relative humidity, plus other variables and the set with absolute humidity plus other variables were separately adopted in the variable selection in order to draw two final models. the best fitted model was then chosen based on aic value (lower being better). adjusted r-square (adj-r ) is the measure of proportion of variance explained by the model after the parsimony adjustment. the difference of adj-r between the null model and fitted model (Δadj-r ) was interpreted as the proportion of variance explained by the meteorological factors. we conducted a sensitivity analysis addressing two aspects: ( ) model parameters: sensitivity analysis was performed by varying the length of the gi for days and days [ ] and the cfp for . % and . % [ ] . ( ) model structure: in addition to the linear form of equation ( ), a multiplicative exponential form was also adopted in model fitting to test whether this would produce different results: table summarizes the results of the best fitted models with lowest aic and all statistical significant meteorological parameters. compared with the null models (βt = constant), models with meteorological parameters had better goodness of fit in terms of their aic (figure ). no null model was found to be the best fitting model after the stepwise variable selection. with the exceptions of the and p&i waves, adj-r was always greater than %, indicating that models with selected meteorological parameters explained more than % of the variance in p&i mortality after the adjustment of number of parameters. except for , the models with significant meteorological factors could account for more than % of variance in addition to the null model (i.e., Δadj-r > %). for the epidemic, the meteorological parameters accounted for more than % of the variability in the p&i data. nevertheless, the p&i data of the epidemic could not be well explained by the best fitted models. as shown in table , air temperature and rainfall were the most common significant variables driving the seasonal variations of the p&i waves from to . the air temperature was negatively associated with the time-varying transmission rate βt in six of the seven epidemics; for one sd decrease in temperature, the transmission rate would increases by . , . , . , . , . , . (× − ) for the years , , , , and respectively. moreover, rainfall was positively associated with the transmission intensity in five of the seven epidemic waves. when there was a sd increase in rainfall, the transmission rate would increases by . , . , . , . , . (× − ) for the years - , and respectively. a negative association was found for . surprisingly, relative humidity and absolute humidity did not show much contribution to the variance of βt among all the p&i epidemics. a sensitivity analysis was conducted to test the impact of our results from different parameter settings. in brief, varying the cfp ( . % and . %) and gi ( and days) only produced a slight effect on the goodness of fits. as shown in figures and , the best fitting curves were highly similar. in terms of aic and adj-r , no significant differences were produced as a result of using different cfp and gi settings (tables and ). the fitness of the models with either cfp = . % or gi = days were worse than the other models in several epidemic waves. the effect of temperature was only slightly sensitive to the variation in cfp and gi. in most situations, air temperature continued to be identified as a common driver of seasonal variations. when gi = days, air temperature significantly drove the variations in all epidemics. whereas the effect of rainfall was moderately sensitive to variations in cfp and gi. rainfall was identified as the significant driver of four of the studied influenza epidemics. the decrease of rainfall's significance may be due to the model variance shared with relative humidity. the meteorological variable selection was not sufficiently sensitive, even if the model structure was changed to the exponential form (table s ). recent studies have demonstrated that environment factors account for a proportion of the seasonality, as well as infection oscillations, of influenzas in temperate regions [ , ] . here we used a mathematical model to explore the potential meteorological drivers for seasonal oscillations of influenza in a subtropical city, hong kong. through modulating the transmission rates by the meteorological factors in an infectious disease model, the seasonal variations of influenza infections could be well-depicted. according to our results, although no meteorological parameters dominated the seasonal variations for all epidemics, air temperature significantly modulated the fluctuations of transmission rates for most of the epidemics between and . rainfall was also found to be a significant driver for most of the epidemics, although its direction of association was not unidirectional and it was moderately sensitive to changes in the model parameters. in many laboratory and epidemiological studies, air temperature is often found to be associated with influenza transmissions [ , [ ] [ ] [ ] [ ] [ ] . an epidemiological study from chan et al. [ ] found that temperature and relatively humidity were associated with the activity of seasonal influenza in hong kong; a cold and humid climate was related to higher activities of both influenza a and b. lowen et al. [ ] conducted an experimental study using a guinea pig model to demonstrate that cold temperature favored to the spread of the influenza virus. our study extended these findings by showing that cold temperature was associated with the mechanism driving seasonal oscillations at a population level. this is perhaps due to prolonged survival of viral particles under colder conditions. nevertheless, the effect of temperature could be confounded by other factors [ ] . for example, a decrease in temperature could enhance crowding at indoor activities, and would thus increase the contact, aerosol and droplet transmission intensity. in our study, we could not identify any strong evidences that absolute humidity drove the seasonal variability in hong kong, even though experimental and modeling studies have shown that absolute humidity was related to viral survivorship and was capable of driving the seasonality of influenza in temperate regions [ , , ] . one possible explanation for this is that the absolute humidity in hong kong was high all year around, compared to temperate areas. like other tropical and subtropical regions, use of air conditioning is common in hong kong when the temperature is high. one could argue that, using air conditioning would lower the indoor absolute humidity and thus modulate the survivorship of the influenza virus. the effect from air exchange would indeed offset the impact of disease transmission. in addition to cold temperature, experimental studies have indicated that a low relative humidity could enhance the influenza transmission [ ] . according to our results, relative humidity was not identified as a significant driver for the seasonal variation of influenza infection. this might be accounted for by the relative unpopularity of indoor heating in hong kong compared to temperate regions. moreover, the predominant mode of influenza virus spread was proposed to be different between temperate and tropical regions [ ] . relative humidity would be more insensitive for transmissions by the contact route than by the aerosol route. previous studies shown that rainfall could be used as a predictor to forecast influenza infection rates for sub-tropical regions, but not in all temperate regions [ ] . these authors also indicated that rainfall was correlated with seasonal influenza transmission in hong kong [ ] , and this finding was in line with other tropical areas [ ] . nevertheless, there remains no clear and definitive explanation for the mechanism of rainfall driving the influenza seasonality. although low temperature and dry air have been proven to be favorable for survival of viral particles [ ] , no study has investigated the relationships between rainy conditions and bulk aerosol transport. one plausible mechanism is that rainfall could affect human social behaviors, such as indoor activities, and therefore influence the number of contacts and the risk of exposure to contaminated environments or infected individuals. in our study, we found that rainfall significantly drove some epidemics but that its direction of association was not unidirectional, likely due to the problem of multicollinearity, which has been investigated in our association analysis (table s ) . solar radiation could cause seasonal variations in vitamin d photosynthesis that may affect immune responses as well as playing a role in the influenza seasonality [ , ] . the preventive efficacy of vitamin d supplementation against influenza infections has also been demonstrated in trial studies [ ] . our study did not identify solar radiation as a driver for the seasonality of influenza infection. this result was not surprising because the effect of solar radiation on the population of the subtropics is not as well documented as in temperate regions. in addition, influenza a would be more likely affected by vitamin d status than influenza b [ ] . this factor might confound our findings when p&i data was adopted in the study. nevertheless, the role of solar radiation in seasonality remains controversial because it has been difficult to explain the influenza dynamic in outdoor environments; most transmissions occur in indoor environments through airborne transmission or contact [ ] . rather than pooling all of our data, the purpose of conducting the analysis by seasons was to investigate the meteorological effects independent of the between-season variations. the between-season effect was made up by "nuisance variables", which could result from variations of reporting rate and other potential factors that affected the susceptibility numbers [ ] , such as the vaccination effectiveness. although the partial immunity of the seasonal influenza was adjusted in our analysis, some factors are difficult to measure and interpret. analysis by seasons could confound the relationship between meteorological factors and transmission rate, and thus generate inconsistency for the estimated coefficients (e.g., a negative association of rainfall in ). an additional analysis was conducted using the pooled data and the results were summarized in supplementary table s . by this approach the main finding was unchanged (i.e., a low temperature drove the influenza transmission). it should be noted that between-season effect accounted for % of the total variance in addition to the meteorological determinants. in our study, there is undoubtedly some degree of correlation between meteorological variables. hence, we additionally conducted a correlation analysis in which the pearson correlation coefficients and variance inflation factors (vif) were drawn from the pooled data, with the results summarized in supplementary table s . although positive correlations were found between temperature and solar radiation, and between rainfall and humidity, no serious effect of multicollinearity was found for any of the predictors based on a simple rule-of-thumb (i.e., all vifs were less than ). one limitation of our study is that we only investigated the environmental drivers for disease transmission and could therefore not completely rule out confounding factors. according to some studies [ ] [ ] [ ] ] , some seasonal changes of host behavior (e.g., international travel [ , ] and school holidays [ ] ) might also affect the transmission dynamics. it has been shown that the closure of kindergartens and primary schools was able to reduce the disease transmission rate by around % for the influenza a/h n pandemic. nevertheless, its effect upon the seasonal variation of influenza is controversial. some studies [ , ] pointed out that no substantial effect on the transmission reduction could be detected when schools were closed. in addition, our results were undoubtedly affected by the demographics of the population (e.g., age and gender). subjects with different clinical status, such as chronic obstructive pulmonary disease, may also have confounded the likelihood of p&i deaths. the sufficiency of details to address these issues requires a huge effort in data collection, which remains difficult to achieve at this stage. further research is warranted to investigate the effects of seasonal social/behavior patterns. a limitation to our study is that the use of p&i mortality to represent the influenza activity may not be completely adequate and could potentially bias the findings. although some studies have preferred using p&i mortality [ ] , we also analyzed the p&i excess mortality to test the robustness of the study finding. we adopted the traditional serfling approach to estimate the excess mortality [ , ] . the serfling method is a linear regression model using harmonic terms to calculate the expected mortality in the absence of influenza virus activity. the number of excess deaths attributable to influenza was estimated as the difference between the observed and the upper % limit of the prediction interval of baseline deaths. the details were noted in supplementary table s . from the results, the principal finding was unchanged (i.e., air temperature remained a significant driver of the seasonal patterns). it should be noted that no climatic variables can be fitted into the year due to few p&i excess mortality. this might be due to the mitigation measures for the severe acute respiratory syndrome (sars) epidemic that potentially also reduced the number of influenza cases [ ] . undoubtedly, it has been widely recognized that the disease severity of influenza, in terms of excess p&i deaths and hospitalization, tended to be higher in the influenza a dominant seasons than in those with influenza b as the dominant virus strains [ ] . moreover, some influenza b epidemics resulted in increased hospitalizations but not increased mortality [ ] . as a result, our findings might be less precise for mild influenza seasons and may not reflect the general influenza experience in hong kong. this is a common limitation in studies that employed mortality surveillance. in addition to death data, influenza-like illness (ili) surveillance has been commonly adopted as a proxy for influenza activity. nevertheless, the definition of ili failed to document significant influenza-associated morbidity and mortality [ ] . as such, ili is a poor indicator of influenza activity when adopted in areas with a less defined pattern of seasonality [ ] . laboratory surveillance data would be a better indicator for influenza activity but large efforts would be required to gather and collate such data. the data used in this study was only applied the retrospective fitting. further studies would have to be conducted to validate these results. for example, more data is required to extend the model application to projecting the sir curve for model validations [ ] . plausible causality and potential interactions should also be justified, such as direct and indirect effects of air temperatures [ ] . nevertheless, our study represents an initial step towards identifying potential meteorological determinants for driving the seasonal variations of influenza in a subtropical region. this study identified the potential meteorological drivers for the seasonal variations of influenza in a subtropical city, hong kong. results show that the cold air temperature was a significant driver for increasing the transmission intensity of seasonal influenza from to . rainfall was also found to be a significant driver for some seasons, although this result was less robust. an accurate would enable officials to take appropriate control measures for influenza epidemics, such as maintaining sufficient indoor temperature and enhancing vaccination activities prior to the cold seasons. further laboratory and epidemiological studies are required to validate and justify the associations proposed here. seasonal influenza activity in hong kong and its association with meteorological variations influenza in tropical regions influenza seasonality: lifting the fog fact sheet influenza-associated mortality in hong kong influenza-associated hospitalization in a subtropical city dynamical resonance can account for seasonality of influenza epidemics absolute humidity and the seasonal onset of influenza in the continental united states shortcomings of vitamin d-based model simulations of seasonal influenza driving factors of influenza transmission in the netherlands the government of the hong kong special administrative region: table : population figures from mid- to mid- . mid-year population for the computation of equivalent potential temperature. mon. weather rev Über einige meteorologische begriffe comparison of algorithms for the computation of the thermodynamic properties of moist air the reproduction number of seasonal influenza epidemics in brazil centers for disease control and prevention. seasonal influenza: clinical signs and symptoms of influenza finding the real case-fatality rate of h n avian influenza seasonal influenza in the united states, france, and australia: transmission and prospects for control model selection and multimodel inference: a practical information-theoretic approach modeling and predicting seasonal influenza transmission in warm regions using climatological parameters influenza virus transmission is dependent on relative humidity and temperature influenza seasonality: underlying causes and modeling theories hospital admissions as a function of temperature, other weather phenomena and pollution levels in an urban setting in china associations between mortality and meteorological and pollutant variables during the cool season in two asian cities with sub-tropical climates: hong kong and taipei absolute humidity modulates influenza survival, transmission, and seasonality high temperature ( ºc) blocks aerosol but not contact transmission of influenza virus meteorological parameters as predictors for seasonal influenza the role of temperature and humidity on seasonal influenza in tropical areas the seasonality of pandemic and non-pandemic influenzas: the roles of solar radiation and vitamin d influenza, solar radiation and vitamin d. dermatoendocrinology randomized trial of vitamin d supplementation to prevent seasonal influenza a in schoolchildren a note on the inactivation of influenza a viruses by solar radiation, relative humidity and temperature modeling the impact of air, sea, and land travel restrictions supplemented by other interventions on the emergence of a new influenza pandemic virus assessing the impact of airline travel on the geographic spread of pandemic influenza school closure and mitigation of pandemic (h n ) effects of school closures, winter influenza season methods for current statistical-analysis of excess pneumonia-influenza deaths the impact of influenza epidemics on mortality: introducing a severity index respiratory infections during sars outbreak the impact of influenza epidemics on hospitalizations clinical signs and symptoms predicting influenza infection this study was supported by the project ( zx - ) from the shenzhen research institute, the chinese university of hong kong, shenzhen, china. the authors thank the hong kong observatory, the hospital authority and the environmental protection department for providing the datasets for this study. the authors also thank external reviewers for their expertise advice on constructing the manuscript. william goggins and maggie haitian wang collected the data and conducted the data analysis. ka chun chong conducted the data analysis, summarized the results, and wrote the manuscript. benny chung ying zee initiated the research and revised the manuscript. all the authors read and approved the final version of the manuscript. the authors declare no conflict of interest. key: cord- -oezkz m authors: tung, w.l.; quek, c. title: financial volatility trading using a self-organising neural-fuzzy semantic network and option straddle-based approach date: - - journal: expert syst appl doi: . /j.eswa. . . sha: doc_id: cord_uid: oezkz m financial volatility refers to the intensity of the fluctuations in the expected return on an investment or the pricing of a financial asset due to market uncertainties. hence, volatility modeling and forecasting is imperative to financial market investors, as such projections allow the investors to adjust their trading strategies in anticipation of the impending financial market movements. following this, financial volatility trading is the capitalization of the uncertainties of the financial markets to realize investment profits in times of rising, falling and side-way market conditions. in this paper, an intelligent straddle trading system (framework) that consists of a volatility projection module (vpm) and a trade decision module (tdm) is proposed for financial volatility trading via the buying and selling of option straddles to help a human trader capitalizes on the underlying uncertainties of the hong kong stock market. three different measures, namely: ( ) the historical volatility (hv), ( ) implied volatility (iv) and ( ) model-based volatility (mv) of the hang seng index (hsi) are employed to quantify the implicit volatility of the hong kong stock market. the tdm of the proposed straddle trading system combines the respective volatility measures with the well-established moving-averages convergence/divergence (macd) principle to recommend trading actions to a human trader dealing in hsi straddles. however, the inherent limitation of the macd trading rule is that it generates time-delayed trading signals due to the use of moving averages, which are essentially lagging trend indicators. this drawback is intuitively addressed in the proposed straddle trading system by applying the vpm to compute future projections of the volatility measures of the hsi prior to the activation of the tdm. the vpm is realized by a self-organising neural-fuzzy semantic network named the evolving fuzzy semantic memory (efsm) model. as compared to existing statistical and computational intelligence based modeling techniques currently employed for financial volatility modeling and forecasting, efsm possesses several desirable attributes such as: ( ) an evolvable knowledge base to continuously address the non-stationary characteristics of the hong kong stock market; ( ) highly formalized human-like information computations; and ( ) a transparent structure that can be interpreted via a set of linguistic if–then semantic fuzzy rules. these qualities provide added credence to the computed hsi volatility projections. the volatility modeling and forecasting performances of the efsm, when benchmarked to several established modeling techniques, as well as the observed trading returns of the proposed straddle trading system, are encouraging. volatility modeling and forecasting (poon, ) is imperative to financial market investors. in finance and econometrics, volatility is defined as the intensity of the fluctuations in the expected return of an investment or the variations in the market's pricing of a financial asset. financial volatility forecasts allow the prudent investors to adjust or hedge their investment portfolios to mitigate investment risk and to customize their trading strategies in anticipation of the forthcoming financial market movements. investment risk refers to an extensive set of factors or events that erodes the financial value of an investment (poon, ) . this includes credit risk (i.e. loss due to a debtor's non-payment) and liquidity risk due to the market's small capitalization. hence, financial volatility is one indication of investment risk and is often viewed as a risk metric (holton, ) . financial volatility forecasting is important as volatility is often used as a proxy to measure financial or market risk caused by the underlying uncertainties of the financial market movements (which can have significant positive or negative effects on the values of investment portfolios) due to a myriad of factors. these factors may include recessions, wars, structural changes in the economy, tax law changes, interest rate hikes, inflation pressures, investor anxiety and even changes in consumer preferences. furthermore, when viewed as a measure of market uncertainty, financial volatility is a key input in many investment decisions and portfolio creations (aizenman & marion, ; chan, karceski, & lakonishok, ) . the extensive body of research on volatility modeling and forecasting (anderson, bollerslev, & lange, ; blair, poon, & taylor, ; engle, ; hamid, ; noh, engle, & kane, ; poon & granger, ) has reflected the importance of financial volatility to investment decision-making (busse, ; galeotti & schiantarelli, ; okuyama & francis, ) , security valuation (de santis, gerard, & hillion, ; hsu, ) , risk management (christoffersen & diebold, ; granger, ) as well as monetary policy making (nasar, ) . volatility is also a key component in the pricing of derivative securities such as equity options (duan & simonato, ; figlewski, ; hull & white, ; noh et al., ) , where there has been an exponential growth in the trading volume in recent years due to the extensive use of derivatives instruments as hedging and risk management tools. in addition, national policy makers, financial regulators and central banks often relied on estimates of financial volatility to assess the effectiveness of regulatory measures on the financial markets (poon & granger, ) . given its widespread importance, it is therefore not surprising that financial volatility has emerged as a key asset class in today's financial markets. that is, sophisticated investors can trade in financial instruments defined on market volatility. for example, the vix index (chicago board options exchange) introduced in by the chicago board options exchange (cboe) is based on the short term volatilities of options issued on the s&p index, which tracks the stock performances of large-cap corporations trading on the us stock markets (i.e. nyse and nasdaq). the creation of the vix volatility index allows a savvy investor to leverage on his estimates of the fluctuations of the financial market movements through the use of futures contracts to achieve investment profits during rising, falling and side-ways markets. hence, given the extensive applications of volatility forecasting, the research on financial volatility modeling and prediction has been the primary focus of academics and practitioners of financial econometrics over the years. excellent reviews and research of the subject are reported in knight and stephen ( ) , poon and granger ( ) , hans franses and mcaleer ( ) and poon ( ) . in brief, there are three general notions (measures) of financial volatility in the literature, namely historical volatility, implied volatility and model-based volatility. historical volatility (hv) is backward-looking and is generally computed from a time-series of the continuously compounded returns of the underlying security or asset. in this measure, the compounded investment return r c (t) of the underlying security is computed daily and it is defined as r c (t) = log (c(t)/c(t À )), where c(t) denotes the current closing valuation of the financial security and c(t À ) refers to the price level of the previous trading day. this corresponds to the day-on-day change in the financial valuation of the underlying security. subsequently, the volatility hv(t) for a trading day t is defined as the statistical deviation or weighted deviation of the returns time-series {r c (t À n + ) jn = ,. . . ,n}, where n denotes the length of the historical price path considered in the computation of the volatility measure. implied volatility (iv), on the other hand, is forward-looking as it is derived from the observed (traded) prices of the options issued on the underlying financial instrument. that is, as implied volatility is based on the current market prices of the options, it contains all the forward expectations of the investors about the likely future price path of the underlying security. the implied volatility of an option contract is defined as the financial volatility that produces the traded (market) price of the option based on a selected option pricing model. in practice, the black-scholes model (black & scholes, ) and its variants (gencay & gibson, ; grace, ) are often used to price the options traded in the derivatives markets. empirically, it has been observed that the computed ivs of the options issued on the same underlier and with the same time to maturity often exhibit a nonlinear relationship known as the volatility smile (derman & kani, ; dupire, ) with respect to the different strike prices of the options. this is generally regarded as evidence that an underlier's implied financial volatility is not constant, but instead, depends on factors such as the price level of the underlying security and the exercise prices of the options. for these reasons, at-the-money (atm) or nearly atm options are often used as the reference entities to compute the implied volatilities in financial volatility modeling and prediction studies (poon & granger, ) . in contrast to hv and iv, model-based volatility (mv) is often derived using the autoregressive conditional heteroskedasticity (arch) and generalized arch (garch) family of continuous time process models (bollerslev, ; engle, ) . within the arch and garch frameworks, the objective is to model the continuously compounded investment returns time-series {r c (t)} of an underlying financial instrument using a predictable conditional mean model l(t) and a stochastic conditional variance model that defines the innovations e(t) of the returns time-series, i.e. r c (t) = l(t) + e(t), such that a i r c ðt À iÞ ðautoregressive modelÞ eðtÞ ¼ rðtÞzðtÞ ðstochastic innovation modelÞ ð Þ where t denotes the current trading day; / is a constant; n is the order of the regressive model; z(t) $ n( , ) is a gaussian-distributed random variable; and the (conditional) variance r (t) of the innovations of the time-series {r c (t)} is modeled as an autoregressive process of previous innovations and variances, i.e. r ðtÞ ¼ j þ x n i¼ b i e ðt À iÞ þ x n i¼ c i r ðt À iÞ ðgarch modelÞ ð Þ where j is a modeling constant; and {n , n } are the orders of the garch model. the coefficients {/, a i , j,b i , c i } of the modeling process defined in eqs. ( ) and ( ) are generally obtained via maximum likelihood estimation. the time-varying model-based volatility mv(t) of the underlying financial asset is subsequently defined to be the identified conditional deviation r(t). one of the most important stylized facts of financial volatility is the presence of volatility clustering or volatility persistency in historically observed data, i.e. high volatility is often followed by periods of high volatility and low volatility by periods of low volatility (bollerslev & engel, ) . this empirical observation about financial volatility has deep implications for volatility forecasting, and supports the notion that current and past values of volatility can be used to predict future volatility levels. in this paper, the use of a self-organising neural-fuzzy semantic network named the evolving fuzzy semantic memory (efsm) model (tung & quek, ; tung & quek, ) that employs the notion of incremental sequential learning (ratcliff, ) to model and forecast the volatility levels of the hang seng index (hsi) across a five-year period spanning vix is the ticker symbol for the chicago board options exchange (cboe) volatility index, which shows the market's expectation of the -day volatility. vix values greater than are generally associated with a large amount of volatility as a result of investor fear or uncertainty, while values below generally correspond to tranquil periods in the markets. the hang seng index (hsi) is a capitalization-weighted stock market index in the hong kong stock exchange (hkse). it is used to record and monitor daily changes of the largest companies of the hong kong stock market and is the main indicator of the overall market performance in hong kong. these companies represent about % of capitalization on the hkse. from to is investigated. the computed volatility forecasts are subsequently used to capitalize on the movements of the hong kong stock market by performing straddle trading using an automated option trading system that is based on the moving-averages convergence/divergence (macd) (colby, ; pring, ) principle. there are two primary motivations to this piece of work. they are: ( ) to develop an intelligent trading system endowed with humanlike information processing capabilities and a logical reasoning schema to support the decision-making process of a human trader in performing financial volatility trading, and ( ) to address the lagging (reactive) nature of the macd trading rule and to enhance its timeliness in spotting trading opportunities by introducing forward-looking (forecasting) capability to the computation of the underlying trend signals. these are explained as follows. when employing technical analysis for security trading, a human trader typically analyzes the historical financial (price) data that is available and attempts to identify the salient/recurring patterns that correlate to profitable trades. such information is then used to detect future trading opportunities, constituting the human approach to financial trend modeling and judgemental forecasting (lawrence & o'connor, ) . however, current technical volatility modeling and forecasting methods (a comprehensive review can be found in section of poon & granger ( ) ) are often based on statistical or continuous time finance theories that are generally mathematically convoluted, which erodes their intuitiveness to a human investor. the proposed use of efsm as a semantic neural-fuzzy based approach to the modeling and projection of financial volatility trends, on the other hand, bridges the knowledge chasm as it enables a human investor to examine the inherent trend information extracted from the historical observations via highly interpretable if-then fuzzy rules. moreover, since high frequency financial data is inherently noisy, efsm can mitigate the effects of the noise artifacts on the computed volatility predictions as it employs gaussian-shaped fuzzy sets to model (generalize) the characteristics of the past volatility fluctuations. this helps to preserve the salient patterns and predictable trends of the financial volatility time-series. furthermore, the self-organising efsm can spot financial trends in huge amounts of data that may not be immediately apparent to a human trader. in addition, empirical studies have sufficiently shown that financial (market) volatility is time-varying and non-stationary (mele & fornari, ) . efsm addresses this issue by employing a set of brain-inspired learning mechanisms that functionally mimics the information processing of the human hippocampus, a brain construct located in the medial temporal lobe of the human brain that is vital for the acquisition and continuous on-going organization of the human semantic memories (kandel, kupfermann, & iversen, ) . this enables efsm to construct a more robust and adaptive forecasting model in contrast to many existing neuralfuzzy modeling techniques. furthermore, efsm employs the compositional-rule-of-inference (cri) schema (zadeh, ) , a logical fuzzy reasoning scheme that mimics the human reasoning process, to define its computations. from a human trader's perspective, this provides added credence to the computed volatility projections. lastly, as the macd trading rule employs historical time-indexed data to obtain the trending signals, the resultant trading decisions computed from these signals are inevitably time-delayed. therefore, the use of efsm as a model to forecast the future hsi volatility levels and the subsequent use of such forward projections in the computation of the macd trading decisions help to address the lagging nature of the macd trading rule. this paper is organized as follows. section briefly presents the efsm neural-fuzzy semantic memory model and its learning mechanisms. section then introduces the technical concepts behind the trading of option straddles and the use of the macd principle for financial volatility trading. following that, section describes the hsi data set used by efsm to model and forecast the volatility levels of the hong kong stock market. subsequently, the trading results based on the use of these forecasts for the capitalization of the hong kong financial market uncertainties with a macd-driven straddle trading system are presented and analyzed. section concludes the paper. the evolving fuzzy semantic memory (efsm) model (tung & quek, employed in this work is essentially a neuralfuzzy system (nauck, klawonn, & kruse, ) that consists of five layers of computing nodes as shown in fig. . neural-fuzzy (or neuro-fuzzy) systems are the realizations of the functionality of fuzzy systems using neural networks, and they are regarded as universal data-mining tools that possess a strong capability to derive the intrinsic relationships between the observed numerical inputs and outputs of the training data presented (lin & lee, ) . the main advantage of a neural-fuzzy system is its ability to model the characteristics or solutions of a given problem using a set of if-then fuzzy rules instead of low-level complex mathematical expressions. from fig. , the structure of the efsm model employed for the modeling and projection of the hang seng index volatility implements the mamdani fuzzy model (mamdani, ) , a system of knowledge representation that is characterized by a set of linguistic if-then fuzzy rules r k (k = ,. . ., k) of the form described by eq. ( ). where x = [x , . . ., x i , . . . , x i ] t and y = [y , . . ., y m , . . . , y m ] t denotes the inputs and outputs of efsm respectively; i is the number of inputs; m is the number of outputs; il ði;j i Þk (j i = ,. . ., j i , k = ,. . ., k) denotes the j i th fuzzy set of input x i in rule r k ; ol ðlm;mÞk (l m = ,. . ., l m ) is the l m th fuzzy set of output y m in the consequent of r k ; k is the number of fuzzy rules; and j i and l m is the number of fuzzy sets of x i and y m , respectively. in efsm, k, j i and l m varied according to the changes in the underlying data generating process to be modeled. in this paper, the underlying process refers to the hong kong financial market uncertainties that give rise to the volatilities of the hang seng index. the computing structure of the efsm model evolves dynamically with the arrival of each training data presented. the learning mechanisms of efsm are designed to functionally emulate the information processing capabilities of the human hippocampus (see section . ). prior to the start of the learning process, there are no computing nodes in layers , and of efsm (i.e. no fuzzy rules). new fuzzy rules are dynamically added and old rules that no longer describe the current data characteristics observed are removed during the learning phase. together, the set of resultant fuzzy rules describes the salient associative mappings between the inputs and outputs of the underlying process being modeled. the form of knowledge representation described in eq. ( ) is also known as linguistic fuzzy modeling (lfm) (casillas, cordn, herrera, & magdalena, ) , and best approximates the semantic knowledge (e.g., long-established knowledge about objects, facts, and word meanings etc.) representation embodied in the human mind (toth, ) . with respect to the task of financial volatility modeling and forecasting, this knowledge representation scheme enhances the interpretability of the efsm computing structure (by defining the neural connectionisms of efsm as human comprehensible if-then fuzzy rules) and helps a human trader to develop a better understanding of the underlying characteristics of the observed volatility of the hang seng index movements. this directly enables the human investor to analyze and study the volatility trends in the hong kong stock market and to make better and informed trading decisions to maximize his investment profits. over the last decade, neural-fuzzy systems have been successfully deployed to solve many modeling problems (chong, quek, & loh, ; juang & lin, ; quek, tan, & sagar, ; quek, wandy, & ng, ; talei, chua, & quek, ; tan, quek, ng, & ravzi, ; tong, wang, & tang, ; tung, quek, & cheng, ; wai & lin, ) . however, the complex and dynamic nature of real-world applications demanded that neural-fuzzy systems be able to adapt their structures, parameters and ultimately evolve their intelligence to continuously address the non-stationary characteristics of the underlying data generating processes. the usefulness of existing neural-fuzzy systems such as anfis , popfnn (ang & quek, ; quek & zhou, ) , hyfis (kim & kasabov, ) , efunn (kasabov, ) , sofnnga (leng, mcginnity, & prasad, ) , rpop-tvr (wong, cho, & quek, ) , fascom (goh, lim, & quek, ) and fitsk (quah & quek, ) are, however, generally constrained to static environments as their training/rule generation procedures unrealistically assumed that the characteristics of the underlying data generating processes being modeled do not change with time. hence, these systems often employed batched or pseudo-incremental learning approaches to construct (i.e. identify and tune) their respective fuzzy rule (knowledge) bases and are ill-equipped for the modeling of more complex time-varying processes. these neural-fuzzy systems lacked the capability to acquire any new information that emerges after the training of the embedded fuzzy model has been completed. attempts to adapt to the changing underlying process generally require re-training to rebuild the entire neural-fuzzy system since incremental learning of the new patterns (information) will modify the trained fuzzy model in such a way that the originally learned but possibly still valid knowledge is forgotten or replaced. that is, the newly emerging information ''catastrophically" erased the fuzzy model's memory of the previously learned knowledge (french, ) , and the resultant phenomenon of degraded computing performances is known as the stability-plasticity dilemma (grossberg, ) . in contrast, humans are often observed to learn new things prolifically and spontaneously without forgetting the old information (mcclelland, mcnaughton, & o'reilly, ) . this phenomenon is referred to as sequential learning in machine learning research (mccloskey & cohen, ) . hence, the learning mechanisms of efsm are modeled after certain information processing capabilities of the human brain (specifically the hippocampus) to enable it to robustly organize the knowledge extracted from the data observations presented. particularly, the human hippocampal formation is capable of a neurogenesis process (kempermann, wiskott, & gage, ) that has been regarded as the primary mechanism used to in batch learning, it is assumed that all the training data has been collected and is available to the training process. training generally involves cycling through the collected data a number of epochs to separately identify and tune a fuzzy model that provides a fitting description to the characteristics of the observed training data. pseudo-incremental learning refers to the arrival of the training data one at a time. the training process generally responds by applying the rule generation procedure to the current training data prior to the arrival of the next data sample. however, a copy of the observed data is usually kept for the parameter adaptation phase to optimize the parameters of the fuzzy model or to perform rule pruning to identify a compact rule-base. resolve the learning stability-plasticity dilemma in the human brain (wiskott, rasch, & kempermann, ) during the acquisition of the human semantic memories (eichenbaum, ) . furthermore, empirical evidences have established that the human hippocampus and its surrounding cortices are directly involved in the detection of input novelty and associative novelty to facilitate the recognition of information (brown & aggleton, ; nyberg, ) , which plays a critical role in updating the human representation of the changing world (o'keefe & nadel, ) . these information processing capabilities are generally ascribed to two complementary functions of the human hippocampus; namely, as a recall comparator (vinogradova, ) and as a novelty/familiarity detector (clark & gronlund, ) . therefore, to computationally mimic facets of how the human hippocampus performs the sequential learning of information, the rule-generating procedure of the efsm model is designed based on its recall comparator as well as the novelty/familiarity detection principles. details of this rulegenerating procedure are reported in tung and quek ( ) . in addition, neuroscientists have also established at the neurological level that the human hippocampus maintains its acquired knowledge using two primary synaptic mechanisms: i.e. long-term potentiation (ltp) (whitlock, heynen, shuler, & bear, ) and long-term depression (ltd) (bear & abraham, ) . ltp is the strengthening of the synaptic connection between two repeatedly intensely excited neurons and is responsible for the learning/reinforcement of memory traces in the hippocampal formation. ltd, on the other hand, is the weakening of the synaptic connection between two neurons due to persistent weak excitations. thus, it is regarded as the main mechanism of 'forgetting'. hence, the human hippocampus possesses highly evolved and elegant mechanisms to maintain up-to-date memory traces. computationally, the efsm model mimics these neural mechanisms via the use of fuzzy rule potentials with the ltp and ltd concepts (see section . ) to construct a set of evolving if-then mamdani fuzzy rules to model non-stationary data generating processes. the following describes the computational process employed by the efsm model. each layer performs a specific function with respect to the cri reasoning schema. layer (input layer): each node represents an input variable to efsm. the set of layer nodes iv i (i = ,. . . , i) acts as singleton fuzzifiers and directly transmits the input vector x to layer . this is described in eq. ( ). where iv i (x i ) denotes the output of node iv i given the input x i . layer (antecedent layer): this layer encapsulates the input fuzzy sets in the antecedents of the fuzzy rules generated by the efsm model (see eq. ( )). the fuzzy sets (representations) denote the generalized concepts elicited from the training data. in this paper, gaussian-shaped fuzzy sets are used. the membership value il i;j i ðx i Þ of input x i to the j i th fuzzy set of iv i (denoted as il i;j i ) is given by eq. ( ). where l i;j i denotes the gaussian membership function of il i;j i ; and ðq i;j i ; h i;j i Þ are the center and standard deviation of the gaussian membership function respectively. layer (rule layer): this is the rule-base of the efsm model which contains the mamdani-typed fuzzy rules dynamically de-rived from the training data. the firing of a fuzzy rule r k is computed as eq. ( ). where l ði;j i Þk denotes the gaussian membership function of the input fuzzy set (representation) il i;j i that is an antecedent of r k . layer (consequent layer): this layer consists of the output fuzzy sets (representations) that formed the consequents of the fuzzy rules in efsm. each output fuzzy set ol lm;m is represented as a gaussian membership function l lm;m defined by center q lm;m and standard deviation h lm;m . as more than one fuzzy rule may have the same expected consequent, the activation of an output fuzzy set ol lm;m is defined as eq. ( ). where r lm;m denotes the set of fuzzy rules in efsm that shares the same consequent ol lm;m . layer (output layer): each node in this layer corresponds to an output variable of the efsm model. the function of an output node ov m (m = ,. . . , m) is to combine the activations and inferred results of all its output fuzzy sets in layer to produce a response y m (x) to the input vector x. this is described in eq. ( ). where ol lm;m ðr lm;m Þ ¼ ol lm ;m ðr lm;m Þ= p lm lm¼ ol lm ;m ðr lm;m Þ; and co lm;m ðl lm;m ; xÞ is the inferred consequent output of the fuzzy set ol lm;m (represented by l lm ;m ) due to the activation of the efsm rule-base by input x. the inferred consequent outputs in efsm are essentially computed based on a fusion of the mamdani as well as the takagi-sugeno (ts) (takagi & sugeno, ) fuzzy models (tung & quek, ). this ensures that when compared with existing mamdanibased neural-fuzzy systems, the efsm model is able to deliver a better performance in time-series modeling and prediction tasks. subsequently, the computed output y m (x) of ov m is the weighted sum of the set of inferred consequent outputs from all the output fuzzy sets of ov m . following that, the output of efsm to the input x is defined as y = [y (x), . . . , y m (x), . . ., y m (x)] t . although the efsm model employs a set of learning mechanisms that is inspired by the human hippocampus, its computing structure remains similar to that of the well-established generic self-organising fuzzy neural network (gensofnn) (tung & quek, ) . hence, the procedure of mapping the cri schema onto efsm to define its computational process described in eqs. ( )-( ) shall not be repeated here. the interested reader may refer to tung et al. ( ) on how such mapping is performed. similar to gens-ofnn, efsm may also take on other forms of fuzzy reasoning schema such as truth-value restriction (mantaras, ) , approximate analogical reasoning (turksen & zhong, ) and yager reasoning (yager, keller, & tahani, ) . the reader may refer to tung and quek ( ) , tung and quek ( ) and oentaryo, pasquier and quek ( ) for more details. the backward connections (dashed arrows in fig. ) from layer to layer via layer are activated during the structural learning of the efsm model (i.e. identification of the fuzzy rules) and the computation of the fuzzy rule potentials (see section . ) based on the observed training pattern pair (x, d), where d is the defined (target) output vector (or experience) in respond to the input stimulus x. this is described as follows. layer : the set of layer nodes ov m , m = ,. . . , m, directly transmits the defined output vector d to layer . that is (see eq. ( )), where d m is the mth target output for efsm with respect to the input x. layer : during structural learning or computation of the fuzzy rule potentials, layer nodes perform an operation similar to the layer nodes. that is, the membership value ol lm;m ðd m Þ of desired output d m to the l m th fuzzy set of ov m is given by eq. ( ). where l lm;m denotes the gaussian membership function of ol lm ;m that is defined by center q lm ;m and standard deviation h lm;m . layer : the backward activation of a fuzzy rule r k is defined as eq. ( ). where l ðlm ;mÞk denotes the membership function of the output fuzzy set ol lm;m that is a consequent of r k . in the efsm model, the addition of a new fuzzy rule is governed by its rule-generating procedure that is derived from the observed functions of the human hippocampus as a recall comparator and novelty/familiarity detector. this resolves the stability-plasticity dilemma of efsm as a knowledge learning system. however, obsolete fuzzy rules that no longer describe the observed data characteristics due to changes in the underlying data generating process have to be pruned from efsm in order to maintain a compact and current rule (knowledge) base. this is achieved via the use of fuzzy rule potentials and the ltp and ltd concepts introduced in section . . the potential p k of a fuzzy rule r k in efsm defines its importance/influence in the entire rule (knowledge) base of the system. hence, a fuzzy rule with a high potential is significant in describing or generalizing the characteristics of a large chunk of recently encountered training patterns. each rule in efsm has a fuzzy rule potential that is continuously computed based on the ltp and ltd principles. the potential p new of a newly created fuzzy rule is defined as unity, and p k is updated based on the current training data pair (x(t), d(t)) using eq. ( ). where p k (t) is the potential of rule r k prior to the presentation of the training pair (x(t), d(t)); and r k (x(t)) and r back k ðdðtÞÞ are as defined in eqs. ( ) and ( ), respectively. hence, the significance (potential) of the associativity of a fuzzy rule in efsm is enhanced or reinforced if its input conditions and expected consequents are similar to the information expressed in the training pair (x(t), d(t)). this functionally mimics the ltp mechanism observed in the human hippocampus. in a changing environment, the training data used to construct the fuzzy rules is only temporally relevant. existing fuzzy rules in the efsm model may become obsolete and no longer reflect the current knowledge as the dynamics of the underlying data generating process changes. hence, a forgetting mechanism is employed to systematically remove the unwanted rules (memory associations) from efsm. this reduces the complexity of the fuzzy rulebase and maintains a set of up-to-date fuzzy rules that describes the current characteristics of the underlying process being modeled. forgetting is simulated by reducing the potentials of the fuzzy rules according to their current values. this is described in eq. ( ). where k is the forgetting rate. this generates exponential forgetting and results in a decay of the significance of a fuzzy rule r k in efsm. rule r k is removed from the rule-base of efsm if its potential falls below a fraction of that assigned for a newly created fuzzy rule, i.e. p k (t + ) < tp new . in this paper, t and k are pre-defined as . and . respectively. combining eqs. ( ) and ( ), the overall potential of a fuzzy rule r k in efsm is defined as eq. ( ). hence, if a fuzzy rule is deemed important, its ltp component will be significant and contributes to a high rule potential. this eventually keeps the fuzzy rule within the rule-base of efsm. on the other hand, if a fuzzy rule has become insignificant due to changes in the underlying process, then ltd will be dominant in the computation of its rule potential. this subsequently results in a low fuzzy rule potential and the rule is removed if its potential falls below the pre-determined threshold tp new . this section introduces the technical concepts behind option straddles and the moving-averages convergence/divergence (macd) trading principle, and describes how they are used for financial volatility trading to capitalize on the uncertainties in the hong kong stock market. an option is a contract between two parties -a buyer (holder of the option) and a seller (writer of the option) -that gives the buyer of the traded option the right, but not the obligation, to purchase or sell an underlying physical or financial asset at a future date and at a pre-agreed price. options provide a means to manage financial risks and are playing an increasingly important role in modern financial markets (chance, ) . from a financial perspective, having the right to buy or sell an asset without the obligation to complete the transaction has economic value. therefore, options are traded as an asset in the financial markets. options belong to a class of financial products generally referred to as derivative securities whose returns are derived from those of other financial instruments, in this case, the underlying physical or financial assets for which the options are issued (boyle & boyle, ) . options are traded openly on derivative markets such as the chicago board options exchange and the chicago mercantile exchange or overthe-counter privately between two parties. in the option markets, the price of a traded option depends on several factors. these include the price of the underlier (which determines the intrinsic value of the option), time to maturity of the option contract (which influences its time value), market volatility of the underlying asset, the current risk-free interest rate, the strike (exercise) price of the option and the type of option contract (i.e. american or european contract). in this paper, the options issued on the hang seng index are european contracts and all future discussions are based on such european options. the price dynamics of a call (right to buy) and put (right to sell) option are illustrated in fig. . in addition, the intrinsic value and the profit/loss (p/l) functions are shown together with the respective option prices to indicate the lower-bound valuations and the returns of investment of the two options with respect to the changing underlying asset price s . for an at-the-money (atm) call option, a denotes the market (purchase) price of the option. hence, a trader stands to lose at most a capital equivalent to a should the option expires at-the-money or out-of-the-money (otm); i.e. s t x, where s t is the price of the underlier at the time the option expires. however, if the price of the underlier increases above the exercise (strike) price of the call option, the option will become in-the-money (itm). if the call option expires as in-the-money, its value is derived from the difference of the underlier price and the strike price; i.e. c t = s t À x, where c t is the value of the call option at expiration. hence, the overall profit/loss (p/l) to a trader for investing in the call option is computed as p/l = max ( , s t À x) À a. this is reflected as the p/l function in fig. (a) . the price dynamics, intrinsic value and profit/loss functions for a put option are analyzed in a similar way. from fig. (b) , the label b denotes the capital invested in buying a put option that is at-the-money. for a put option, as the price of the underlier decreases, the value of the option increases and vice versa. when the price of the underlying asset is zero, the maximum theoretical price of a put option is x (i.e. no investor will pay more to receive a lesser payout). the profit/loss to an investor for investing in a put option is determined by p/l = max ( , x À s t ) À b. hence, a trader loses at most the capital of b if the atm put option that he has bought expires with no value (i.e. max ( ,x À s t ) = jx s t ). on the other hand, he will breakeven on his investment if the put option expires with a value of b (i.e. {b = x À s t js t < x}). when the value of the put option exceeds b, a profit is made on the investment. in the derivatives markets, a straddle is an option trading strategy with which an investor simultaneously holds a position in both a call and a put option with the same strike price and expiration date. fig. depicts the expected profit/loss to a trader who invests in an atm straddle with respect to the changing underlying asset price. the cost of the call, put and resultant straddle are denoted as a, b and c, respectively. straddles are a good strategy to pursue if an investor believes that an underlier's price will move significantly (i.e. high price volatility), but is unsure as to in which direction the price will move. as shown in fig. , the underlying asset price must move significantly if the investor is to make a profit from buying (longing) the atm straddle. if there is only a small movement in the underlier's price occurring in either direction (i.e. low price volatility), the investor will experience a loss as the value of the straddle is less than the capital outlay of c to purchase it. the investment on the straddle is said to break-even when the value of the straddle equals to its acquisition price c = a + b. on the other hand, the reverse is true for selling (shorting) the atm straddle. that is, a trader will suffer a loss if he sells a straddle and the underlier's price subsequently experienced high volatility or encountered a large price movement in either direction. a profit is possible only if the price of the underlying asset does not deviate too far from the strike price of the straddle sold (i.e. low price volatility). hence, an intelligent straddle trading system is proposed in this paper to capitalize on the financial volatility of the hong kong stock market. such a trading system will long (short) a straddle defined on the it is assumed here that a put option costs more than a call option. this could be due to a bearish market where the price of the underlying asset is expected to fall. the reverse may be true for a bullish market where the underlier's price is expected to rise. nevertheless, the technicalities of straddle trading outlined here apply for both scenarios. hang seng index when high (low) volatility of the index movement is expected. the moving-averages convergence/divergence (macd) technique is a momentum oscillator (appel, ; colby, ) employed to perform technical analysis on financial time-series to predict trend changes for security trading. the primary mechanism of macd is to use moving averages (which are lagging indicators) to track the movements in a financial data time-series such as a stock market index or the price of a financial asset. the use of moving averages attenuates or smoothes the spurious oscillations (rapid reversals of trends) and helps to identify the general movements of a time-series. commonly, macd is defined as the difference (see eq. ( )) between the -days exponential moving average (i.e. ema ) and the -days exponential moving average (ema ) of a time-series, although other time periods may also be used. that is, and the exponential moving average (ema) of a price/index data series p is computed as eq. ( ): where ema n (t) is the current n-days ema of the data series p; ema n (t À ) is the previously computed ema; p(t) is the current observed value of p; and k = /( + n) is the smoothing constant. ema and ema are also popularly known as the fast and slow signals of the macd trading rule, as the former tracks a shorter historical time frame and is therefore more responsive to recent movements of the data series than the latter. hence, a more generic definition is macd = ema fast À ema slow . fig. depicts the fast and slow ema for the stock price of merrill lynch co. from august to november . in the top half of the figure, the fast ema (ema ) for the stock price of merrill lynch co. is shown as the solid line, while the slow ema (ema ) is denoted by the dashed line. in fig. , the vertical bars denote the daily trading ranges of the stock price of merrill lynch co. and the left and right ridges on the bars reflect the opening and closing stock prices, respectively. the daily closing stock prices are used to compute the -and -days ema that are overlaid on the price plot. as one can observe from the figure, both the fast and slow ema are lagging indicators as the ema signals captured the trend reversals much later after the direction of the stock price of merrill lynch co. has changed. from eq. ( ), macd tracks the difference between the fast and slow ema. macd is positive when ema is above ema and vice versa. the macd for the stock price of merrill lynch co. is represented as a thick solid line in the lower half of fig. . a crossover between the two ema signals occurs when one rises over (falls under) the other. this is reflected by the three instances when the macd signal cuts the zero reference line. macd is often referred to as a momentum oscillator as the macd signal oscillates above and below the zero reference line, and an increasing difference between the two ema signals reflects a faster rate-of-change of one signal over the other. hence, if the fast signal (ema ) is rising quicker than the slow signal (ema ), a positive (bullish) momentum is captured by computing the macd. conversely, if the fast signal is falling more swiftly than the slow signal, a negative (bearish) momentum is observed. with a technical understanding of the macd principle, one can construct an autonomous trading system to buy/sell an asset by identifying the crossover points between the fast and slow ema. hence, such a trading system would recommend a buy if ema rises above ema or sell if the reverse happens. however, the lagging nature of the two ema signals often causes the crossover points to be detected some time after the trend reversals have occurred. since the objective for constructing an autonomous trading system is to assist a human trader to maximize the possibility of profitable trades by using and analyzing market information to determine a trading position in anticipation of the price/trend changes (cheng, quek, & mah, ; guo, ) , the delayed trading signals from the macd trading rule are not very useful in this case. in addition, the macd trading rule with the zero reference line as a trigger is also susceptible to whipsaws when the macd signal oscillates rapidly around the reference line. this generates false or insignificant trading signals and incurs unnecessary trading costs. hence, the -days ema of the macd signal is often used as the trigger line for the macd trading rule as it attenuates the oscillations and smoothes the macd signal. the ema of the macd signal (i.e. macd_ema ) is shown as the thin solid line in the bottom half of fig. . the macd histogram is depicted as the bar plot and illustrates the differences between the macd signal and its ema trigger line. this formulation of the macd trading rule is often referred to as macd ( , , ) , where the respective historical time frames for the fast and slow ema signals as well as the trigger for the macd signal are clearly specified. with macd ( , , ) , a buy (sell) signal is generated whenever the macd signal crosses above (falls below) its ema trigger line. as observed from fig. , the trading signals generated by macd ( , , ) are much closer to the lows and highs of the stock price plot. empirical studies have further validated and confirmed the shorter delays of the trading signals generated by such a process (elder, ; murphy, ) . in this paper, the macd principle described above is employed in an intelligent straddle trading system to perform financial volatility trading so as to capitalize on the uncertainties of the hong kong stock market movements. the proposed straddle trading system is part of a trading framework modeled after the work of moody and his colleagues (moody & saffell, ; moody, wu, liao, & saffell, ) , where a technical analysis approach has been applied for security trading and portfolio optimization. the straddle trading framework is depicted as fig. . at the core of this trading framework is the proposed straddle trading system that operates on the known (observed) values of the input financial data series (in this case the financial volatility measures of the hong kong stock market) to derive the trading decisions for the buying and selling of the option straddles issued on the underlying hang seng index (hsi). the hsi is the main indicator of the stock market performance in hong kong and its fluctuations therefore served as a proxy to the financial volatility of the hong kong stock market. the performance of the straddle trading system is subsequently evaluated by analyzing the investment returns r(t) from the straddle trades that were performed, which eventually defined the overall financial profit or loss r achieved by the system that is inclusive of the trading costs d incurred. specifically, the straddle trading system in fig. consists of two individual modules: the volatility projection module (vpm) and the trade decision module (tdm). as described earlier, the macd trading rule employs the notion of moving averages that subsequently results in the generation of delayed trading signals. in order to address this inherent limitation of the macd trading rule for the proposed straddle trading system, the predicted future values of the volatility measure of hsi are employed in the computation of the fast and slow ema signals. let y = {y(t), y(t À ), y(t À ), . . .} denotes the time-ordered sequence of the financial volatility measures (i.e. historical, implied or model-based volatilities) characterizing the movements of the observed hang seng index up to the current time t. since y is a regularly-sampled time-series with no missing value, the prediction of the immediate future value of y (i.e. y(t + )) given the observed historical values of the time-series (i.e. y(t), y(t À ), y(t À ), . . .) can be formulated as an autoregressive problem f as shown in eq. ( ). yðt þ Þ ¼ f ðyðtÞ; yðt À Þ; . . . ; yðt À n þ ÞÞ whereŷðt þ Þ denotes the predicted immediate future value of the time-series y; and n is the modeling horizon or embedding dimension (packard, crutchfield, farmer, & shaw, ; vitrano & povinelli, ) that defines the number of past values and the delays to be used for the prediction. the prediction objective is therefore to minimize the error (difference) betweenŷðt þ Þ and the subsequently observed actual time-series value y(t + ). in financial time-series prediction or financial forecasting, the autoregressive problem f as shown in eq. ( ) has been optimized via various techniques (e.g. statistical regression, stochastic regression, neural networks, fuzzy systems, support vector machines and evolutionary computations) for stock price modeling and prediction (ang & quek, ; saad, prokhorov, & wunsch, ) , forecasting of financial variables (noh et al., ; refenes, burgess, & bentz, ) , equity returns (apte & hong, ; kuan & liu, ) and stock market indices (chen, leung, & daouk, ; yang & yang, ) , as well as the optimization of portfolio composition and trading strategy (moody & saffell, ) . in this paper, the efsm model that employs a set of human hippocampal-inspired learning mechanisms is used as a forecasting system to predict the future volatility measure of the hang seng index. the volatility forecasts, when used in the computations of the fast and slow moving averages of the corresponding hsi volatility time-series, will enable the macd trading rule to generate forward-looking trading signals. that is, the macd trading rule will make a recommendation to buy (short-sell) an atm straddle in order to profit from its increased (decreased) valuation whenever high (low) volatility in the hong kong stock market is expected. this approach directly addresses the problem of delayed trading signals inherent in the original formulation of the macd trading rule. the predicted future volatility levelŷðt þ Þ of the hsi is subsequently forwarded to the trade decision module (tdm) of the proposed straddle trading system (fig. ) to compute the trading decision td(t) that is defined as eq. ( ) hence, on any trading day t, the proposed trading system can issue a sell, buy or no trading recommendation to a human trader. for simplicity, in this paper, the trading system is allowed to have at most one open trading position. that is, the trading system may have short-sold an atm straddle when the hsi volatility is expected to be low or bought an atm straddle if the hsi volatility is expected to increase. otherwise, the trading system would be in a neutral position with no exposure to the fluctuations of the hong kong stock market. the status (focus) of the proposed trading system on trading day t is denoted by f(t) such that on the last trading day (i.e. end of the simulation/trading period), the trading system will close any existing open position where f(t À ) {À , } to return to a neutral position (i.e. f(t) = ) and computes the profit/loss (return r s (t)) on the last straddle trade as well as the overall profit/loss r for the entire trading (simulation) period. to account for the profit/loss r s (t) of trading an option straddle s, the trading system needs to monitor the initial and final economic values of the straddle that was traded. let v s, denotes the initial value of the atm straddle s when the trading system first bought or sold it, and v s, denotes the final value of the straddle s when the trading system closes its position on it (i.e. reversing its open position). the profit/loss r s (t) of trading a straddle s is computed only when the trading system returns to a neutral trading position from a short-sold or longed position as shown in fig. . computationally, the profit/loss or return r s (t) for a straddle trade s performed by the proposed trading system is defined by buy atm straddle at least one month from expiration. set ( ) . short-sell atm straddle at least one month from expiration. set ( ) . eq. ( ) and the overall profit/loss r for the trading period is defined by eq. ( ) respectively. that is, where d is the transaction cost in percent of the total value of the hsi options transacted; s denotes the total number of straddle trades performed during the simulated trading period; and the values v s, and v s, of a straddle s referred to the aggregated market prices of the underlying atm call and atm put option on the hsi at the time of buying (selling) and selling (buying) of the straddle respectively. hence, the objective of the proposed straddle trading system is to capitalize on the volatility of the hsi to maximize the total trading return r. in this paper, d is defined as % of the total economic value of the options transacted and eq. ( ) accounts for two different ways of computing the transaction cost of performing a straddle trade, i.e. ( ) when the trading system closes its open position on the straddle, and ( ) when the straddle expires and the trading system subsequently returns to a neutral trading position. the transaction cost for the former scenario is d(v s, + v s, ) since the atm straddle s is transacted twice at value v s, and v s, , respectively, while the transaction cost for the latter scenario is d(v s, ) since settlement is automatically performed when the straddle expired. with respect to fig. , the trade decision module (tdm) of the proposed straddle trading system has to derive one of three different sets of trade decisions, namely td short (t), td neutral (t) and td long (t), depending on the trading scenario encountered. that is, tdm is to recommend the appropriate trading action td short (t) when the trading system (i.e. trader) is in a short-sold position, the trading action td neutral (t) when the trading system is in a neutral position, and the trading action td long (t) when the trading system is in a longed position, respectively. each of these three sets of trade decisions contains two or three types of trading actions, i.e. sell atm straddle, no trading and buy atm straddle as described in eq. ( ). the breakdowns of the various trade decisions are presented as follows. (a) trader has short-sold (shorted) an atm straddle (i.e. f(t À ) = À ): the trade decision module has to decide on the appropriate trading action (denoted as td short (t)) for the current trading day t based on the conditions described in eq. ( ). where d macdðt þ Þ is the difference between the projected fast and slow ema of the hang seng index volatility time series (denoted as d ema fast ðt þ Þ and d ema slow ðt þ Þ respectively in fig. ); and d macd emaðt þ Þ is the trigger line for the macd trading rule to generate the straddle trading signals as described in section . . (b) trader is in a neutral position (i.e. f(t À ) = ): the tdm of the proposed straddle trading system has to decide whether it is now an appropriate time to trade an atm straddle and the trading action to be performed is derived according to eqs. when d macd emaðt þ Þ < : when d macd emaðt þ Þ ¼ : hence, one can observe that a no trading band of - % of the trigger line d macd emaðt þ Þ is defined to prevent false trading signals being generated due to whipsaws. this reduces the detrimental effects of accruing unnecessary transaction costs from the excessive trading of the option straddles. (c) trader has bought (longed) an atm straddle (i.e. f(t À ) = ): the trade decision module decides whether to sell off the straddle or to maintain the holding position based on eq. ( ). that is, therefore, the proposed straddle trading system will hold onto the longed position if the hsi volatility is expected to increase or change minimally. otherwise, the trading system will sell off the option straddle and returns to the neutral position. in addition, fig. shows that the trade decision module (tdm) of the proposed straddle trading system may activate an exit strategy whenever the trader has an open longed or short-sold position on an atm straddle (i.e. f(t À ) {À , }). as straddle trading is a highly leveraged financial activity and carries a certain amount of risk (especially with an open short-sold position), such an exit strategy helps to lock-in big trading profits as well as serves as a stop-loss mechanism if the market conditions turned unfavorable. the condition to trigger the exit strategy can be: (c ) the value of the longed (shorted) straddle s has been below (above) the initial traded straddle value v s, for consecutive trading days, or (c ) the current value v s (t) of the traded straddle (as compared to v s, ) has declined sharply, or (c ) the value v s (t) of the traded straddle has increased significantly. conditions (c ) and (c ) prevent excessive losses and locks in big profits from the straddle trade respectively. the exit conditions are mathematically defined in eqs. ( ) hence, according to eqs. ( ) and ( ), the proposed trading system will apply the exit strategy to close its open position on the atm straddle whenever the traded straddle experienced a % decline in its market value or has achieved a % gain in its traded price. this limits the downside risk while allowing the trader to reap significant profits from the correct projections of the hong kong stock market volatility. on the other hand, condition (c ) ensures that the trader is not in a losing position (albeit a small one) for a prolonged period of time. in summary, the above discussion presents the computational mechanisms (trading strategy) of the proposed intelligent straddle trading system that consists of a volatility prediction module based on the efsm semantic neural-fuzzy network and the macd-driven trade decision module that generates the trading signals for the straddle trades. the next section evaluates the performance of the straddle trading system using real-life data obtained from the hong kong stock exchange (hkse). the raw dataset used in this research consists of the daily closing information of the hang seng index (hsi) options across a year period spanning from january to december , which corresponds to a total of trading days. the information in the dataset includes the expiry dates, strike prices, daily settlements and the daily black-scholes implied volatilities of all the live european-styled options issued on the hsi, as well as the recorded closing levels of the hong kong bourse (i.e. the hsi) during the observation period. all the information is obtained via the hong kong exchange corporation (hong kong exchange). from the daily closing levels of the hsi and the information recorded in the options dataset, the three volatility measures of the hong kong stock market, namely the historical volatility (hv), implied volatility (iv) and model-based volatility (mv) as described in section , are computed. these respective volatility measures subsequently formed three different time-ordered data series. the hv timeseries is obtained via eq. ( ), which uses the -days historical standard deviation of the log-returns series {r c (t)} as a proxy to the implicit hsi volatility. that is (see eq. ( )), where r (t) denotes the historical standard deviation of the logreturns of the past trading days (i.e. r c (t), . . ., r c (t À )). the computed historical volatility measure hv(t) for trading day t has been annualized with a normalizing factor of ffiffiffiffiffiffiffiffi ffi p as there is approximately trading days in a calender year. the iv time-series, on the other hand, is derived from the observed closing values of the hsi european options. at each trading day t, the first-in-the-money (fitm) and first-out-of-the-money (fotm) call and put options with at least two months to expiration are identified. the average of the implied volatilities of these four options is the approximated at-the-money (atm) iv measure. hence, from eq. ( ), iv(t) of the hsi at trading day t is defined as where iv fitm(call) (t), iv fitm(put) (t), iv fotm(call) (t) and iv fotm(put) (t) denote the black-scholes implied volatility for the fitm and fotm call and put options respectively on trading day t. lastly, the model-based volatility (mv) of the hsi is estimated from the log-return series {r c (t)} of the hang seng index (hsi) using the composite conditional mean and conditional variance financial time-series model based on the autoregressive (ar) and the garch (bollerslev, ) processes (see eqs. ( ) and ( )). the hv, iv and mv based timeseries of the hsi fluctuations are depicted in fig. . as one can observe from the plots of the three volatility measures, the hong kong stock market has experienced greater fluctuations and higher volatilities in the first half (i.e. jan to mid ) as compared to the later half of the -year observation period. this could be due to the post september- effects (where there were a lot of uncertainties and fears about the strength of the us economy after the terrorist attacks and the related fallout on the health of the global economy), as well as the sars (severe acute respiratory syndrome) outbreak in asia in early that greatly eroded investors' confidence in the asian stock markets. nevertheless, it is important to note that the volatility time-series derived from the three different measures generally displayed similar macro volatility trends across the -year period, although there are significant differences in the amplitude of the fluctuations as well as conflicting pockets of volatility trends. in this paper, the efsm neural-fuzzy model is employed as a robust volatility forecasting system to predict the future volatility levels of the hang seng index (hsi) given the past volatility observations. this constitutes the volatility projection module (vpm) of the proposed intelligent straddle trading system. efsm possesses several desirable attributes such as ( ) base to continuously address the non-stationary characteristics of the hong kong stock market; ( ) highly formalized human-like information computations; and ( ) a transparent structure that can be interpreted by a human trader via a set of linguistic if-then semantic fuzzy rules to understand the volatility trends in the hong kong financial market. for this research, it is assumed that the future volatility level y(t + ) of hsi can be approximated from the volatilities observed for the past ten trading days (i.e. two trading weeks). that is, from eq. ( ), yðt þ Þ ¼ f vpm ðyðtÞ; yðt À Þ; . . . ; yðt À ÞÞ ð Þ whereŷðt þ Þ denotes the predicted value of y(t + ); and f vpm is the nonlinear regression function to be approximated by the efsm model. hence, there are ten inputs to the efsm-based vpm and a single output which is the predicted volatility for the next trading day (t + ). the structure of the efsm-based vpm is illustrated as fig. . in this paper, the efsm model is employed to construct a modeling and prediction system for the hv and iv time-series only. that is, only the hv and iv data-series are used to evaluate the trend modeling and prediction capabilities of the efsm model. the mv time-series, which is derived using the conditional mean and conditional variance financial time-series model based on the ar and garch processes, will be directly used to study the trading performances of the proposed straddle trading system. the computed trading profit/loss based on the use of the mv time-series subsequently serves as a benchmark to the trading results obtained with counterpart straddle trading systems employing the efsm-based hv and iv projection modules. no forecasting system is constructed for the mv time-series. this is because empirically, it is not necessary to model the composite ar and garch processes which in turn trace the dynamics of the hsi returns time-series to derive the model-based volatility (mv) estimates. subsequently, the hv and iv-based time-series are partitioned into two mutually exclusive segments, i.e. a training set and a test set. the training set consists of documented volatility data observed for the initial two years (i.e. jan to dec ) while the test set contains data recorded for the remaining three years (i.e. jan to dec ) of the observation period. the efsm volatility modeling and prediction system is trained using information in the training set and its forecasting accuracies duly assessed using the withheld test set. four measures are adopted to track the modeling and forecasting capabilities of the efsm-based vpm. they are, namely: ( ) the pearson correlation index (denoted as pc) (rodgers & nicewander, ) ; ( ) the mean squared error (mse) (lehmann & casella, ) ; ( ) the average relative variance (arv); and ( ) the mean absolute percentage error (mape) measures. the pearson correlation index pc, with a range of [À , + ], is a measure of the linearity of the predicted and actual volatility trends. that is, a correlation of + indicates a perfect positive correlation, which means that both the predicted and actual hsi volatilities move in the same direction together. the mse, arv and mape measures, on the other hand, tracks the forecast accuracies of the predicted to the actual observed hsi volatility levels. the mse, arv and mape measures are mathematically defined in eqs. ( )-( ), respectively. arv ¼ p n i¼ y ðiÞ Àŷ ðiÞ À Á p n i¼ ðy ðiÞ À yÞ ð Þ where y (i) denotes the actual observed hsi volatility level for trading day i in the test set;ŷ ðiÞ is the corresponding predicted volatility computed by the efsm-based vpm; y ¼ =n p n i¼ y ðiÞ represents the baseline mean output prediction; and n denotes the number of trading days in the test set. of the performance indicators specified in eqs. fig. . volatility projection module of the proposed straddle trading system, where z À is a delay element. accuracies of the efsm model to the mean output predictor. lastly, mape tracks the mean absolute error in percent between the actual and the efsm forecasted values across all volatility observations in the hv and iv time-series. to capture the overall volatility modeling and forecasting capabilities of the efsm-based vpm, the various measures are combined into a performance index pi such that the modeling (recall) and forecasting (generalization) results of the efsm-based vpm on the historical volatility (hv) time-series are depicted as fig. . for both the recall and generalization assessments, the efsm model has been trained using the training set defined earlier. in recall, the trained efsm model is assessed using inputs from the training set (i.e. to determine how well it has learnt the volatility trend information in the training data) while for generalization, the efsm model is evaluated with the unseen inputs from the test set. the tracking measures and the performance indices for the recall and generalization tasks are presented with the result plots. from fig. , one can observe that the efsm model is able to capture the historical volatility trends in the training set relatively well (refer to recall results for the period [ ] [ ] . this is reflected by a high pearson correlation (pc) value of . as well as a low mean squared error mse of . . this small modeling error is also tracked by mape, which indicated that on average, the error expected of the predicted historical volatility level for each trading day in the training set is approximately . % of its true (subsequently observed) value. the arv measure also showed that efsm performed superbly when compared to the baseline mean output predictor. the forecasting capability of the efsm model is subsequently evaluated using the withheld test set. as observed, the accuracy of the predicted volatility levels for trading days of - that constitutes the test set degrades when compared to the recall performance of efsm on the training set. this is indi-cated by the larger mse, arv and mape values. specifically, the mean expected forecast error for the historical volatility level of each trading day in the test period has increased to approximately %. on examination, the lower forecast performance of efsm on the test set is due to significant prediction errors at two prominent durations in the test period. these durations are denoted as subperiod 'a' and 'b' respectively in fig. . subperiod 'a' is characterized by a series of intense fluctuations in the hv data-series, and this could have contributed to the large prediction errors by the efsm-based volatility projection module. on the other hand, the poor performance by efsm at subperiod 'b' could be due to the lack of similar trends in the training set. it is observed that at subperiod 'b', there is a significant increase in the volatility of the hong kong financial market as shown by the sharp rapid rise from trough to peak of the volatility curve. however, similar volatility trends in the training set have a smaller magnitude of increase and this is followed by a rapid fall. hence, this could have caused efsm to forecast a plunge in the volatility level, leading to significant prediction errors in the result plot. the task of modeling and forecasting the historical volatility measures of the hsi is subsequently repeated using other modeling techniques. they are, namely: ( ) a -layered back-propagation trained feed-forward neural network with hidden nodes (ffnn-bp); ( ) a radial basis function (rbf) network (moody & darken, ) with hidden nodes; ( ) the cerebellar model articulation controller (cmac) (albus, ) neural network; ( ) hyfis (kim & kasabov, ) ; and ( ) the anfis network. these computational methods replaced the efsm model as the function approximator in the vpm illustrated in fig. . the benchmarking techniques are selected based on their established performances in time-series modeling and prediction. determined to obtain credible results for comparison with those achieved with the efsm model. for ffnn-bp, linear activation functions are used for the single output as well as the hidden nodes, while the hyfis network employs a configuration of fuzzy partitions per input dimension that subsequently results in trained fuzzy rules. the anfis network, on the other hand, is implemented as part of the matlab fuzzy logic toolbox (matlab fuzzy logic toolbox) and employs subtractive clustering for its structure identification process that generates a total of takagi-sugeno (ts) functional fuzzy rules. lastly, the rbf network employs hidden nodes with gaussian basis functions as local models to learn the volatility trends in the training set and the cmac structure is defined with memory cells per input dimension. for cmac, a total of memory cells are populated after the training process. in addition, the volatility modeling and prediction tasks are repeated ten times with the ffnn-bp model and the average result reported in table in order to address the issue of differing results due to the random initialization of the network's weight matrix. table clearly showed that with the exception of the ffnn-bp model, the rest of the benchmarking systems are able to achieve a good modeling (recall) performance on the training set of the hv time-series. specifically, the anfis and cmac networks are able to produce more superior results than the efsm model. this is likely due to the use of linear functions to model the desired output volatility levels as in the case of anfis and the use of local models and precise scalar outputs to learn the complex volatility trends in cmac. the ffnn-bp model, on the other hand, performed poorly in the recall task due to significant modeling errors as indicated by the various accuracy measures. the conflicting and complex volatility trends were not adequately captured by ffnn-bp, which uses a set of globally tuned weights to model the characteristics of the training set. meanwhile, the hyfis and rbf networks obtained just marginally poorer recall performances on the training set of the hv time-series as compared to the efsm model. however, with respect to the generalization task, table revealed that there are significant degradations in the prediction accuracies of the benchmarking techniques. noticeably, anfis and cmac produced the poorest results amongst all the evaluated modeling techniques. for anfis, this is due to the functional (linear) computation of the predicted volatility levels based on the presented inputs using the takagi-sugeno (ts) fuzzy model, which tends to 'over-extrapolate' its forecasts around subperiod 'a' (see fig. ) that is characterized by a series of small but intense volatility fluctuations in the hong kong stock market. the cmac network, on the other hand, had poor generalization performance for the unseen volatility trends in the test set as it employed discrete (and uniformly spaced) partitions to define its memory surface. this caused many untrained (or under-trained) memory cells to be accessed and resulted in poor volatility forecasts. meanwhile, the ffnn-bp model, as expected, returned another set of disappointing results for the generalization task as it had earlier failed to properly model the volatility trends of the training set. the remaining two benchmarking systems, namely hyfis and rbf, performed better than the three techniques discussed above. a plausible reason is the use of gaussian-shaped fuzzy sets in hy-fis to model both the input and output clusters of the volatility data space, and the use of gaussian radial basis functions in the rbf network to define the local models employed to model the volatility fluctuations. this equips the two modeling techniques with better generalization capabilities for the unseen volatility trends in the test set. however, the results in table have clearly shown that the forecasting (generalization) performance of the efsm model compared favorably to all the benchmarking techniques. specifically, efsm achieved the highest performance index (pi) of . amongst all the evaluated modeling techniques and also had the smallest prediction errors as indicated by the various accuracy measures. this superior performance is possibly due to the use of gaussian-shaped fuzzy sets to model the volatility trends in the training set as well as the learning and computational processes of the efsm model. in addition, the brain-inspired learning process of the efsm model elicits a set of highly interpretable linguistic fuzzy rules from the volatility data in the hv training set. the ltp and ltdbased mechanisms (section . ) ensures a compact rule-base and enables efsm to extract the salient data structures present in the training data. such fuzzy rules enable a human trader to understand the volatility fluctuations of the hang seng index and help him to make informed trading decisions. fig. depicts the set of input-output fuzzy sets extracted from the trained structure of the efsm model. appropriate linguistic labels with the associated semantic meanings have been attached to these fuzzy sets to describe the resultant set of trained fuzzy rules. this compares favorably against the ffnn-bp, rbf and cmac techniques, which do not allow any meaningful interpretation of the acquired knowledge via their trained structures. on the other hand, although the hyfis and anfis networks are neural-fuzzy systems like the efsm model, there are deficiencies inherent to these two techniques that hinder the efforts of a human trader to decipher their acquired knowledge. specifically, the training process of hy-fis causes excessive and unconstrained overlapping of its computed fuzzy sets, which makes assigning proper semantic meanings to these fuzzy sets difficult. the anfis network, on the other hand, employs the ts fuzzy model that computes with functional consequents. this subsequently reduces the transparency and interpretability of its fuzzy rule-base. the hang seng index (hsi) volatility modeling and forecasting task is subsequently repeated using the iv time-series. fig. illustrates the modeling and forecasting results of the efsm-based vpm. the training and test sets of the iv time-series are constructed in a manner similar to that for the hv measure. from fig. , one can observe that the efsm model has achieved considerably consistent results across the recall and generalization tasks. that is, there is only a slight degradation in performance as indicated by the respective performance indices pi. specifically, the expected error for each volatility projection increased from approximately . % for the recall assessment using the training set to about . % for the generalization evaluation using the test set. this increase in forecasting error on the test set is plausibly due to noticeable wayward projections occurring at subperiods 'c' and 'd' denoted in fig. . in addition, when compared to the hv modeling and forecasting results depicted in fig. , one can easily conclude that the efsm model has achieved a better overall performance in volatility projections using the iv time-series data. this could be attributed to the fact that the iv time-series has smaller volatility fluctuations and simpler trend dynamics than the hv-based data. similar to what was performed in section . , the modeling (recall) and forecasting (generalization) evaluations are repeated using the ffnn-bp, rbf, cmac, hyfis and anfis, techniques. again, the network structure and learning parameters of the various benchmarking techniques have been empirically determined to obtain a set of credible results for comparison with the performance of the efsm model. specifically, the ffnn-bp network has hidden nodes and linear activation functions for the single output as well as the hidden nodes, and the hyfis model employs fuzzy sets per input that identifies trained fuzzy rules. the anfis network derives ts functional fuzzy rules while rbf uses local models to learn the volatility trends in the iv training set. similar to the previous set of experiments, the cmac structure is defined with memory cells per input dimension and there is a total of populated cells after the training process. the respective benchmarking results are subsequently tabulated as table . one can observe from the results listed in table that for the recall task, the hyfis, anfis and rbf networks reported better modeling performances than efsm. in fact, they are the top three performers amongst all the evaluated techniques. this could be due to the fact that hyfis and anfis (for the input space only) employed gaussian fuzzy sets to model the characteristics of the iv fluctuations, while the rbf network uses gaussian radial basis functions to define the local models employed to learn the volatility trends in the iv training set. recall assessment as they may have failed to adequately capture the inherent characteristics of the training set. however, when called upon to generate volatility forecasts using data from the test set, the results in table showed that there are marked degradations in the performances of the benchmarking techniques. particularly, there are major declines in the performance indices (see pi readings in table ) reported by the hyfis, rbf and cmac networks, and also a significant increase in the forecast errors for the volatility projections computed by these techniques as indicated by the mse, arv and mape measures. such degraded performances can be explained by the significantly different volatility levels encountered in the test period as compared to the volatility levels in the training set of the iv time-series. specifically, the implied volatility of the hsi fluctuated between % to % between to , while the years to see the same volatility measure within the range of % to %. hence, to the hyfis, rbf and cmac networks, there are significantly lower volatility levels in the test set that they have not encountered during the training phase. this causes large forecasting errors in the volatility projections computed by the three networks. on the other hand, ffnn-bp, anfis and efsm performed considerably better than the previous three benchmarking techniques on the iv test set. this is due to the use of a linear activation function for the output node in ffnn-bp, the linear consequent function in the ts fuzzy model of the anfis network, and the computation of the output of the efsm model via a fusion of the mamdani and ts fuzzy models. more importantly, table has shown that efsm has a better forecasting capability than the ffnn-bp and anfis networks, as it is able to sufficiently capture the volatility fluctuations in the training set using the brain-inspired ltp and ltd learning mechanisms and to sensibly extend the acquired knowledge to derive projections for the unseen test set. this section presents the trading results of the proposed intelligent straddle trading system based on the use of the macd trading rule and the computed hv and iv forecasts from sections . and . . the simulated trading duration is defined as the last three years (i.e. jan to dec ) of the observation period. as benchmark, the mv time-series is directly employed to study the performance of the straddle trading system and the computed trading profit/loss serves as a baseline comparison to the trading results of counterpart trading systems employing the hv and iv projections. in addition, the performances of trading systems employing the efsm-based volatility projection module (vpm) are also evaluated against the results of traders with a hypothetic perfect-predictor (pp) vpm. that is, with respect to eq. ( ), the ppbased vpm generates perfect forecast ofŷðt þ Þ ¼ yðt þ Þ. table lists the various trading results. specifically, two different aspects of the trading performances of the various straddle trading systems evaluated are reported in table . they are: ( ) the mean and standard deviation of the profit/loss e r s ðtÞ (in percent) for each straddle trade performed, and ( ) the overall profit/loss e r (in percent) achieved by a trading system for the simulation period to the total investments committed. e r may also be interpreted as the return on every unit hong kong dollar committed to the straddle trades during the trading period. the results are expressed in percentages to facilitate the comparison of the trading performances for the various counterpart trading systems employing different hsi volatility measures and the efsm or pp-based vpm. with respect to eqs. ( ) and ( ) where r s (t) is the computed return (profit/loss) for the traded straddle s; the value v s, denotes the initial investment committed by the evaluated trading system to take an open (longed or shorted) position on the straddle s; and s is the total number of straddle trades performed during the simulated trading period. from table , one can observe that regardless of the volatility measure used, the trading gains achieved by the proposed straddle trading system employing the pp-based vpm are significantly positive after accounting for the % transaction cost. this is reflected by the large positive gains for the expected profit/lossr s ðtÞ for each straddle trade and the overall return e r under the pp-vpm column. the results clearly demonstrated that the capability to predict (project) the daily hsi volatility levels from past historic observations can help a human trader to enhance his investment profits when trading the hsi straddles. in addition, the positive gains recorded by the various trading systems employing either the efsm or pp-based volatility projection module (vpm) indicated that the trading strategy adopted by the trade decision module (tdm) of the proposed straddle trading framework is technically viable in capitalizing the uncertainties of the hong kong stock market for financial volatility trading. that is, the proposed straddle trading system can help a human trader to generate investment profit gains via straddle trading during rising, falling or side-way market conditions. hence, considerable profits can be realized by the implemented trading framework. individually, each of the three volatility measures produced different degree of trading return. table showed that the highest profit gains are consistently achieved by trading systems employing the implied volatility (iv) measure. trading systems adopting the hv measure as a proxy to the implicit hsi volatility, meanwhile, have the lowest trading returns amongst all the evaluated systems. a plausible reason is that implied volatility (iv) is a forward projection of the price path of the underlying asset, which in this case, is the fluctuation of the hang seng index. the statistically based hv measure, on the other hand, is backward-looking and could be less sensitive to information contributing to the existing market sentiments. hence, the iv measure, which is derived from current option price data, may be a more accurate indicator of the anticipated movements of the hsi than the hv measure and subsequently results in much higher trading returns. lastly, the profit gains of trading systems employing the model-based volatility (mv) measure obtained via the composite ar and garch processes fall between those achieved by counterpart systems employing the hv and iv measures. to further demonstrate the viability of the proposed straddle trading framework, the simple average uncompounded daily rate of return dr achieved by the various trading systems for each unit of dollar committed to a straddle trade during the simulated trading period is computed. with respect to eq. ( ), the simple average uncompounded daily return dr is defined as in eq. ( ). where s denotes the number of straddle trades performed during the simulated trading period; and e r s ðtÞ and t s is the respective profit/loss (in percent) and the duration (in trading days) for the straddle trade s. essentially, dr denotes the expected daily rate of return when a trader has an open straddle position. table lists the computed simple average daily return dr of the various trading systems employing different hsi volatility measures with either the efsm or perfect-predictor (pp) based vpm. as comparison, the daily returns of the evaluated trading systems are duly benchmarked to the simple daily interest rate enjoyed by a holder of a hong kong time deposit of less than hk$ , over the same years duration. according to information obtained from the hkma, the average annual return for such hong kong dollar time deposit from january to december is . %. this works out to an uncompounded daily return of approximately . % on a hong kong dollar. from table , one can clearly observe that the uncompounded daily returns derived from the straddle trades using the proposed straddle trading framework (regardless of the volatility measures employed) are significantly higher than the interest rate offered by a hong kong dollar time deposit. in this paper, an intelligent straddle trading system (framework) that consists of a volatility projection module (vpm) and a trade decision module (tdm) is proposed for financial volatility trading via the buying and selling of option straddles to help a human trader capitalizes on the underlying uncertainties of the hong kong stock market. three different measures are employed to quantify the implicit volatility of the hong kong financial market. they are, namely: ( ) the historical volatility (hv), ( ) implied volatility (iv) and ( ) model-based volatility (mv) of the hang seng index (hsi). these measures subsequently formed three timeordered volatility data series characterizing the fluctuations of the hsi. at the core of the proposed straddle trading system is the trade decision module (tdm) that employs the well-established movingaverages convergence/divergence (macd) principle with the various volatility time-series to generate the trading signals (in the form of trade decisions) in response to the different trading scenarios encountered by a human trader. however, the macd trading rule inherently generates time-delayed trading signals due to the use of moving averages, which are lagging trend indicators. this drawback is intuitively addressed by employing a volatility projection module (vpm) that forecasts the future volatility levels of the hsi prior to the activation of tdm. the vpm is realized by a selforganising neural-fuzzy semantic network named the evolving fuzzy semantic memory (efsm) model. efsm approximates a nonlinear regression function that forecasts the future hsi volatility levels based on historically observed fluctuations. the computing structure of the efsm model evolves dynamically with the arrival of each training data presented. the learning mechanisms of efsm are designed to functionally emulate the information processing capabilities of the human hippocampus where prior to the start of the learning process, there are no fuzzy rules in the efsm structure. new fuzzy rules are dynamically added and old rules that no longer describe the current data characteristics observed are removed based on the long-term potentiation (ltp) and long-term depression (ltd) mechanisms observed in the human brain during the learning phase. this allows the efsm model to continuously address the non-stationary characteristics of the hong kong stock market. in addition, the computations of efsm mimics the human way of reasoning and the trained structure of the efsm model can be interpreted by a human trader as a set of linguistic fuzzy semantic rules. these desirable attributes provided added credence to the computed volatility projections. the volatility modeling and forecasting performances of efsm are encouraging when subsequently benchmarked to several well-known computational intelligence based modeling techniques such as the anfis, hyfis and cmac neural networks. lastly, the performance of the proposed straddle trading system is evaluated using the three different volatility measures and reallife data from the hong kong stock exchange (hkse). the results clearly demonstrated that the ability to forecast the future volatility of the hong kong financial market can help a human trader to enhance his investment profits when trading the hsi straddles. more importantly, the observed trading results indicated that the trading strategy adopted by the trade decision module (tdm) of the proposed straddle trading framework is technically viable in capitalizing the uncertainties of the hong kong stock market for financial volatility trading and achieved a significant return over the interest rate offered by a hong kong time deposit account. volatility and investment: interpreting evidence from developing countries data storage in cerebellar model articulation controller (cmac) forecasting financial market volatility: sample frequency vis-a-vis forecast horizon rspop: rough set-based pseudo outer-product fuzzy rule identification algorithm stock trading using rspop: a novel rough set-based neuro-fuzzy approach the moving average convergence-divergence trading method: advanced version predicting equity returns from securities data long-term depression in hippocampus the pricing of options and corporate liabilities forecasting s&p volatility: the incremental information content of implied volatilities and high frequency index returns generalized autoregressive conditional heteroskedasticity common persistence in conditional variances derivatives: the tools that changed finance recognition memory: what are the roles of the perirhinal cortex and hippocampus? volatility timing in mutual funds: evidence from daily returns interpretability issues in fuzzy modeling an introduction to derivatives & risk management on portfolio optimization: forecasting covariances and choosing the risk model predicting the impact of anticipatory action on u.s. stock market -an event study using anfis (a neural fuzzy model) application of neural networks to an emerging financial market: forecasting and trading the taiwan stock index chicago board options exchange (cboe) a novel neuro-cognitive approach to modelling traffic control and flow based on fuzzy neural techniques how relevant is volatility forecasting for financial risk management? global matching models of recognition memory: how the models match the data the encyclopedia of technical market indicators riding on the smile how big is the premium for currency risk american option pricing under garch by a markov chain approximation pricing with a smile hippocampus: cognitive processes and neural representations that underlie declarative memory trading for a living: psychology trading tactics money management autoregressive conditional heteroskedasticity with estimates of the variance of u.k. inflation new frontiers for arch models forecasting volatility. financial markets catastrophic forgetting in connectionist networks stock market volatility and investment: do only fundamentals matter? model risk for european-style stock index options fuzzy associative conjuncted maps networks black-scholes option pricing via genetic algorithms some comments on risk studies of mind and brain: neural principles of learning, perception, development, cognition, and motor control information and option pricing primer on using neural networks for forecasting market variables. the center for financial studies financial volatility: an introduction hong kong monetary authority (hkma) value-at-risk: theory and practice volume-volatility dynamics in an intertemporal asset pricing model the pricing of options on assets with stochastic volatilities anfis: adaptive-network-based fuzzy inference system anfis: adaptive-network-based fuzzy inference systems noisy speech processing by recurrently adaptive fuzzy filters learning and memory evolving fuzzy neural networks for supervised/unsupervised online knowledge-based learning functional significance of adult neurogenesis hyfis: adaptive neuro-fuzzy inference systems and their application to nonlinear dynamic systems forecasting volatility in the financial markets forecasting exchange rates using feedforward and recurrent neural networks exploring judgemental forecasting theory of point estimation design for self-organizing fuzzy neural networks based on genetic algorithms neural fuzzy systems -a neuro-fuzzy synergism to intelligent systems application of fuzzy logic to approximate reasoning using linguistic systems approximate reasoning models matlab fuzzy logic toolbox why there are complementary learning systems in the hippocampus and neocortex: insights from the successes and failures of connectionist models of learning and memory catastrophic interference in connectionist networks: the sequential learning problem stochastic volatility in financial markets: crossing the bridge to continuous time fast learning in networks of locally tuned processing units learning to trade via direct reinforcement performance functions and reinforcement learning for trading systems and portfolios the visual investor: how to spot market trends for fed, a new set of tea leaves foundations of neuro-fuzzy systems forecasting volatility and option prices of the s&p index any novelty in hippocampal formation and memory? gensofnn-yager: a novel braininspired generic self-organizing neuro-fuzzy system realizing yager inference the hippocampus as a cognitive map disentangling cognitive bias in the assessment of investment decisions: derivation of generalized conditional risk attribution geometry from a time series forecasting volatility in financial markets: a practical guide forecasting volatility in financial markets: a review technical analysis explained: the successful investor's guide to spotting investment trends and turning points fitsk: online local learning with generic fuzzy input takagi-sugeno-kang fuzzy framework for nonlinear system estimation popfnn-based fingerprint verification system a novel brain-inspired neural cognitive approach to sars thermal image analysis popfnn: a pseudo outer-product based fuzzy neural network connectionist models of recognition memory: constraints imposed by learning and forgetting functions neural networks in financial engineering: a study in methodology thirteen ways to look at the correlation coefficient comparative study of stock trend prediction using time delay, recurrent, and probabilistic neural networks fuzzy identification of systems and its applications to modeling and control a novel application of a neuro-fuzzy computational technique in event-based rainfall-runoff modelling ovarian cancer diagnosis with complementary learning fuzzy neural network fuzzy adaptive output tracking control of nonlinear systems fuzziness: from epistemic considerations to terminological clarification gensofnn: a generic self-organizing fuzzy neural network genso-fdss: a neural-fuzzy decision support system for pediatric all cancer subtype identification using gene expression data a hippocampal-inspired self-organising learning memory model with analogical reasoning for decision support an adaptive fuzzy semantic memory model based on the computational principles of the human hippocampus a mamdani-takagi-sugeno based linguistic neuralfuzzy inference system for improved interpretability-accuracy representation efsm -a novel online neural-fuzzy semantic memory model genso-ews: a novel neural-fuzzy based early warning system for predicting bank failures an approximate analogical reasoning scheme based on similarity measures and interval valued fuzzy sets. fuzzy sets and systems hippocampus as comparator: role of the two input and two output systems of the hippocampus in selection and registration of information selecting dimensions and delay values for a timedelay embedding using a genetic algorithm a fuzzy neural network controller with adaptive learning rates for nonlinear slider-crank mechanism learning induces long-term potentiation in the hippocampus a functional hypothesis for adult hippocampal neurogenesis: avoidance of catastrophic interference in the dentate gyrus r-poptvr: a novel reinforcement based poptvr fuzzy neural network for pattern classification neural network implementation of fuzzy logic. fuzzy sets and systems short term forecasting of stock market based on r/s analysis and fuzzy neural networks fuzzy logic, neural networks and soft computing key: cord- -e x z rh authors: cruz, christian joy pattawi; ganly, rachel; li, zilin; gietel-basten, stuart title: exploring the young demographic profile of covid- cases in hong kong: evidence from migration and travel history data date: - - journal: plos one doi: . /journal.pone. sha: doc_id: cord_uid: e x z rh this paper investigates the profile of covid- cases in hong kong, highlighting the unique age structure of confirmed cases compared to other territories. while the majority of cases in most territories around the world have fitted an older age profile, our analysis shows that positive cases in hong kong have been concentrated among younger age groups, with the largest incidence of cases reported in the – age group. this is despite the population’s rapidly aging structure and extremely high levels of population density. using detailed case data from hong kong’s centre for health department and immigration department, we analyze the sex and age distribution of the confirmed cases along with their recent travel histories and immigration flows for the period january to april . our analysis highlights hong kong’s high proportion of imported cases and large overseas student population in developing covid- hotspot areas such as the united kingdom. combined with community action and targeted and aggressive early policy measures taken to contain the virus, these factors may have contributed to the uniquely younger age structure of covid- cases in the city. consequently, this young profile of confirmed cases may have prevented fatalities in the territory. recent research has highlighted the importance of a demographic approach to understanding covid- transmission and fatality rates. the experience in hong kong shows that while an older population age structure may be important for understanding covid- fatality, it is not a given. from a social science perspective at least, there is ‘no easy answer’ to why one area should experience covid- differently from another. the hong kong special administrative region of the people's republic of china (hereafter hong kong) is a city and special administrative region of china in the eastern pearl river delta by the south china sea. in , hong kong had roughly . million people in a , -square-kilometre ( square miles) territory while in kowloon, where more than three in ten residents reside, population density is at , persons per square kilometer. this makes it one of the most densely populated territories in the world [ ] . apart from being a rapidly aging society [ , ] , hong kong is also a migration destination. for the period to , the net migration number was , or a net of four in-migrants per , of the population [ ] . hong kong faces the challenge of infectious diseases as a consequence of various factors, including high population density, increasing environmental pollution, high migration inflows and outflows, the emergence of new infections as well as the changing lifestyle and behavior of its residents [ , ] . the most recent significant outbreak was the severe acute respiratory syndrome (sars) outbreak which reached hong kong in march [ ] . based on world health organization (who) data until july , , a total of , sars cases had been identified in the territory, of which people died of the disease [ ] . at that point, it was largely believed that hong kong was unprepared to be one of the epicenters of the sars epidemic. from this recent experience, did hong kong learn from the hard lessons of the past? the who officially declared the novel coronavirus infections (hereafter covid- ) outbreak as a pandemic on march , , after it had spread to more than countries and resulted in tens of thousands of cases within a few months. in hong kong, however, the first case was reported on january , . in early february, the government was strongly criticized for policy responses related to a variety of issues, including the legality of, and access to face masks; border closure; medical fees and quarantine policy [ ] . during this early period, unfavorable comparisons were made with other regional governments (especially macau and singapore) who appeared to be managing the crisis more effectively [ , ] . however, by the time of writing in june , new cases being reported in hong kong-especially local transmissions-are very rare [ ] . that this has occurred without the general lockdown policies seen in other parts of the world is even more remarkable. our study includes an examination of the age and sex distribution of the covid- confirmed cases in hong kong and an exploration of how the different measures to combat this outbreak resulted in a relatively low number of cases and deaths. specifically, as demographers, we wished to explore the extent to which insights from demographic science could assist in explaining the nature of the hong kong experience of covid- . in this paper, we highlight the potential impact of the young profile of the confirmed cases on the total number of mortalities and the effect of early, aggressive policy measures including travel bans, enforced quarantines and contact-tracing imposed by the hong kong government as early as january , in containing the spread of the covid- . data on confirmed covid- cases were taken from the centre for health protection (chp) of the hong kong department of health. we assessed the age and sex distribution of the confirmed cases, discharge status (discharged, hospitalized or died) and type of transmission. we obtained the data regarding cumulative cases by age group from january to april , , which allowed us to determine the age group that registers the highest number of confirmed cases over time. daily migrant inflows and outflows data was retrieved from the hong kong immigration department showing arrivals at each border checkpoint into hong kong broken down by citizenship status. in addition, we retrieved detailed archived datasets pertaining to the travel histories of confirmed covid- cases, which are updated on an almost daily basis by the chp. we excluded travel histories pertaining to domestic travel (buses, trains and ferries) and a small number of journeys pertaining to outbound from hong kong. we linked travel histories to confirmed case identifications (ids) in order to examine the age structure and timing of cases where the apparent source of infection was not in hong kong (i.e. not a community infection). these include cases with a travel history from countries with widespread infection or where infection from a confirmed case who traveled occurred. by doing so, we highlight the importance of returnee hong kong residents from overseas hotspots on the relatively young age structure of confirmed cases during the second wave in march . we also gathered data on policy measures implemented by the hong kong government in order to highlight the possible impact of major border closures and quarantine arrangements imposed by the hong kong government in reducing further numbers of imported covid- infections. we also utilized secondary data for comparative demographic analyses from the hong kong census and statistics department, united nations population division and the chinese center for disease control and prevention. compared with the aging hong kong population [ ] , the covid- confirmed cases have an entirely different distribution. fig shows [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] . less than a tenth ( . %) are aged and over. this age distribution of the local covid- confirmed cases does not fit the general profile of other territories wherein the infections are more concentrated among those in the older age groups. although, of course, this may be related to testing patterns by age, rather than true differences in incidence. the who coronavirus disease situation report shows that as of april , , there were a total of , confirmed cases with reported information on age and sex coming from countries, territories and areas; of these confirmed cases, the median age for males is (interquartile range, iqr: - ) years and for females (iqr - ) years [ ] . examples of territories with an older profile of confirmed cases are mainland china where the majority of confirmed cases ( . %) as of february , belong to the older age groups, at least years old [ ] , and the philippines wherein as of march , , the majority of the confirmed cases are in the age group and older [ ] . there is also an imbalanced sex ratio among the covid- confirmed cases in hong kong with a higher proportion of male cases, representing % of the total. the number of male cases outnumbered females in almost all age groups, except in the - age group where they made up only % of cases. for all other age groups, male cases were between to % of the total; an exception was for those aged under of which % of cases were male, however, the total number of cases at this age was extremely small ( out of the total , cases). this sex profile with a higher prevalence of male cases is similar to the outbreaks in other territories [ , ] the youngest confirmed cases in hong kong were two males under one-year-old while the oldest confirmed case is a -year-old female. nearly half of the , confirmed cases ( . %) had already been discharged from the hospital as of april , . in short, covid- confirmed cases in hong kong were found primarily among the working and school-age groups, and to a certain degree, among men. by april , , almost three months after the first reported case on january , , four deaths among confirmed covid- cases were reported in hong kong. three such deaths were over years old (two males and one female) while the fourth was the case of a -year old male. it is possible that this young age structure of confirmed cases in hong kong contributed to the extremely low numbers of fatalities compared to other territories. a large proportion of hong kong's confirmed cases were 'imported'. three in five confirmed cases ( . %) have travel history from countries with widespread infection or were directly infected by a confirmed case who travelled; hence, they are considered cases with imported transmission (see fig ) . two-fifths of these imported confirmed cases ( . %) are young adults in the age group - years old. the proportion of imported versus local cases differs significantly based on age group. nine in ten of the confirmed cases in the - age group ( . %), the group with the largest incidence of covid- , were in fact imported. in contrast, . % of cases aged - and less than half of those in other age groups are considered imported. most of hong kong's cases in the younger age groups occurred in a second wave of infections during march. before march , , the age group with the highest frequency of covid- cases was - followed closely by the and over age group (see fig ) . however, after march , the number of new cases in hong kong sharply increased, most of these being imported cases in younger age groups. this timing of these imported cases is similar to that experienced by china wherein the imported cases more than doubled starting from march , , mostly coming from countries with high outbreak of covid- infections like the united kingdom (uk), united states of america (usa) and spain [ ] . however, age-specific data about imported cases is not available in china. analysis of the travel histories of hong kong cases suggests that the majority of imported cases in the - age group may be hong kong residents who are studying or working abroad. the travel history data collected and archived by the chp over the study period was matched to case numbers from the case data to study the travel history and age profile of all known imported cases. the data collected by the chp contains the travel histories of all confirmed covid- cases up to fourteen days before the case was reported and formed part of attempts of the government to track and trace the movements of all newly reported cases. this is done in order to contact and isolate anyone with whom they had close contact in the days before the onset of symptoms, including those whom they may have sat close to on flights. of the covid- cases with an overseas travel history tracked by the chp, . % were imported from the uk, . % from the usa and . % each from qatar, canada and switzerland. by far the largest age group with a travel history was those aged - with cases, of which the majority were from the uk ( . %), . % from the usa, and . % to . % each from switzerland, qatar and the netherlands. the next largest group with travel histories was those aged - with cases, nearly half of these coming from the uk ( . %). we are not able to ascertain the employment or other characteristics of these cases. hong kong has a large population of mobile residents who hold citizenship or permanent residency but work, study or are retired overseas. according to the by-census, just under , permanent residents of hong kong were deemed 'mobile', meaning they had spent between one to three months in the city of the previous six [ ] . in , the largest population of mobile residents was those aged - , with a total of , most of whom were registered as students. we were not able to obtain the country of temporary overseas residency from the census data. the next largest population of mobile residents were those aged and over ( , ) who were mostly registered as retired, while a further , were aged to mostly employees or retirees. in addition, according to the by-census hong kong is home to a sizable number of non-permanent residents; many of these residents may return to their home countries on a regular basis for study, work, or family visits. the largest groups of non-chinese nationals were filipinos ( , ) and indonesians ( , ), most of whom work as domestic workers on temporary foreign-worker permits. hong kong was also home to , british citizens, almost , americans and , citizens from south asian countries (india, nepal and pakistan), while a further , hong kong chinese were registered as being domiciled overseas in [ ] . the large increases in newly confirmed cases in the younger age groups, the majority of which were imported, occurred from march , onward (fig ) . this was in tandem with a large increase in confirmed cases and deaths throughout multiple countries in europe, usa and canada. on march , , the hong kong security bureau had announced a 'red outbound travel alert' ('red ota') for the schengen area, announcing a mandatory -day home quarantine for all arrivals from the schengen area. this was followed by a 'red ota' for ireland, united kingdom and the usa on march , with the announcement of home quarantine arrangements for all travelers from the three states to begin four days later (see s table for a full timeline of policy events). fig shows the arrivals into hong kong over the period from january to april , . most arrivals were hong kong residents travelling via the airport. on february , , all land and sea border points were closed except for two control points-the shenzhen bay control point and hong kong-zhuhai-macao bridge. daily arrivals into the city fell dramatically after the end of the chinese lunar new year holidays at the end of january , and took another dramatic fall after the home quarantine arrangements for all arrivals from china were put into place on february , . arrival numbers followed a relatively steady pattern at under , per day until dropping off sharply from march , , when the new -day home quarantine arrangements were put in place for all arrivals into the city, regardless of whether or not they were residents. from march , , all non-residents were barred from entering the city except for nationals of macau, taiwan or mainland china. these border closures and sharply lower inbound-travel movements together with hong kong's aggressive policy of testing, contact-tracing and quarantine of confirmed cases and their close contacts (see s table) undoubtedly contributed to the sharp decline in newly confirmed cases during the month of april [ ] . on april , , hong kong recorded its first day without a confirmed case, from a peak of more than cases per day in late march. social distancing and rapid population behavioral changes also likely played a role, with measures such as wearing masks, working from home and school closures leading to an estimated . % reduction in seasonal influenza incidence [ ] . the containment of a severe local outbreak of covid- in hong kong thus far, and the very high incidence of confirmed cases in younger age groups mostly among hong kong residents returning to the city from overseas hotspot areas, have surely contributed to the very low number of fatalities in the city-state, with only four deaths reported by april , out of , confirmed cases. one death occurred in the years and over age group, out of twelve total cases. in italy, china and south korea, vastly higher case fatality rates were recorded for those in the older age groups; as at march , case fatality rates for those above years old were at . % in italy and . % in south korea [ , ] . this paper takes a social scientific approach to illustrate the particularities of covid- outcomes in hong kong up until now. the paper is a simple, descriptive analysis of the available data on hand. a recent paper highlighted the importance of a demographic approach to understanding covid- transmission and fatality rates [ ] . the paper suggested that 'the age structure of a population may help explain differences in fatality rates across countries and how transmission unfolds.' fig shows the full population pyramid for hong kong in . observing the discrepancy in the shapes of the pyramids in figs and , it is clear the experience from hong kong suggests that age structure alone is not a universal factor in shaping transmission and fatality rates. despite having more than . % of the population and over and an extremely high population density, a package of policies designed to contain the virus spreading from younger imported cases and becoming a sustained local outbreak ensured that case and mortality numbers stayed low. a further difference between hong kong and other settings characterized by higher rates of infection (and fatality) is the lower levels of distribution of residential care and support among older persons. there is strong evidence that people living in residential/nursing homes are particularly vulnerable to not only infection and its rapid spread, but to severe covid- infection and fatality [ ] [ ] [ ] ; so much so that the who referred to care home infection and fatality rates as an "unimaginable human tragedy" [ ] . in a study of official data in ten countries, deaths in care homes account for between - % of all deaths [ ] -although international comparison is difficult because of differences in cause of death reporting as testing procedures. in common with other parts of the world, the hong kong government has issued guidelines to support residential care homes in preventing infection [ ] , as well as offering other support in terms of provision of personal protective equipment (ppes) and infection protection services [ ] and a switch to online care support for those who would ordinarily visit day care centers [ ] . there may thus be institutional reasons for the low levels of transmission among older people. the size and percentage of the older population resident in care homes differs widely around the world [ ] . in the uk, where a high percentage of infections and fatalities have occurred in care homes [ , ] , it is estimated that around . % of the population aged over is resident in care homes [ , ] . in addition, a further . % of that population receive care support in their own homes, including from carers making multiple home visits in a day-potentially another area of risk for infection [ , ] . in contemporary hong kong, meanwhile, the proportion of over s in residential/nursing homes is estimated to be around . % [ , ] . these lower rates of care home residence may have contributed to lower overall transmission and fatality numbers among the elderly by creating lower opportunities for sustained local spread within the elderly population. low-income migrant workers, an already neglected group in terms of health and other support mechanisms during this pandemic [ ] , represent a further group often characterized by communal living. highly elevated transmission rates have been seen in some settings where such migrant workers often live in cramped, unsanitary conditions [ ] . in singapore, for example, over half of the purpose-built and factory-converted dormitories have been affected [ ] ; a factor held primarily responsible for the 'second wave' of infections in the city-state. it has been estimated that some % of all cases have been linked to such dormitories. compared to singapore, such 'dormitories' are rare in hong kong. perhaps the primary, related housing issue in hong kong is 'subdivided housing'; home to up to , poor, urban individuals [ ] and sometimes referred to as 'coffin houses' because of their very small sizes [ ] . while often characterized by poor hygiene, low environmental [ ] and safety standards [ ] , it appears that policy measures in hong kong, which succeeded in stemming local transmission chains, meant these quasi-communal units were not left exposed to rapid covid- transmission. a final possible factor mentioned by dowd et al. [ ] concerns the possibility that 'intergenerational interactions, co-residence, and commuting may have accelerated the outbreak in italy through social networks that increased the proximity of elderly to initial cases.' this would be derived from a mechanism whereby the younger population most susceptible to initial infection [ ] transmit to the elder population through such contact. in hong kong, multi-generational residence is common [ ] , where around % of those aged and over live with their adult children [ ] -much higher than in italy (or, indeed, any other setting in europe or north america characterized by high transmission rates) [ ] . the extremely high population density of hong kong coupled with short distances and highly efficient transport systems means that there is a high degree of residential proximity as well regular contact between older parents and their children. a further dimension of intergenerational, intrahousehold interaction involves migrant domestic workers, who increasingly operate a major means of care support within the household. there is little evidence in hong kong that such workers were responsible for transmission within the household. as such, the hypothesis suggested for italy appears inconsistent with the hong kong case at least. the general quality of population health data in hong kong is generally accepted to be high, not least because of the centralized healthcare system in the territory. furthermore, in this case a very high degree of health surveillance and monitoring was in force throughout the period. this analysis relied heavily on secondary data for both the information on the confirmed cases and travel histories. given this, there are possible concerns for under diagnosis and under reporting especially during the start of the outbreak until before its first peak as have also been observed in other countries [ ] . the unique age and sex distribution of the cases in hong kong may also be affected by testing patterns. there may, of course, have been unreported and/or asymptomatic cases in hong kong which will have escaped our analysis. however, there is no current consensus on such rates of asymptomatic infection and, therefore, how one might either estimate or correct in the hong kong case [ ] . finally, the challenge of ascertaining primary cause of death and the role played by covid- interacting with other factors [ ] [ ] [ ] is not a significant issue in hong kong given the very small number of deaths. a major limitation is that the spread of covid- has not yet ended. any observations of a 'case in progress' are prone to future, unexpected changes which will change the narrative already described. of course, by the time this paper is published it is eminently possible that events have taken a turn for the worse and a third wave of infections occur. despite this, hong kong has clearly demonstrated a capacity to control both the transmission and fatality of covid- until this point. as of june , there have been no covid- ascribed deaths since march , . furthermore, as of april , , hong kong has reported no new cases for the sixth time in ten days [ ] , and there were just five cases of local transmission in the month of may. from the start of may, public facilities began to reopen, some border restrictions were lifted, and civil servants returned to work in their offices. as of mid-june, public facilities such as beaches, libraries, museums, swimming pools have largely reopened, as have the last group of commercial leisure/entertainment facilities (karaoke lounges, nightclubs, bathhouses and party venues). clearly, much more research is required to concretely establish both the epidemiological and social factors contributing to the hong kong experience. the data which will allow such analysis will only come on stream in the future. at this point more complex statistical analysis will be able to be performed. furthermore, it will then become possible to link data on transmission and fatality through to other clinical and vital records (including the planned census in ). such data will also need to be complimented by survey data and qualitative research to provide a broader sense of the hong kong context. policy interventions, institutional systems, household and living arrangements each played a role in a complex, interwoven way. however, we must not overlook the role played by the community itself who, through behavioral change and increased vigilance, appear to have been equally instrumental in shaping hong kong's covid- experience. it may be in this way that the greatest lessons of sars have been learned [ ] . supporting information s table. timeline world population prospects: the revision the population problem in pacific asia remeasuring ageing in hong kong sar; or "keeping the demographic window open prevention and control of communicable diseases in hong kong. government printer the sars epidemic in hong kong: what lessons have we learned? who. cumulative number of reported probable cases of sars. in: who [internet reasons hongkongers are angry about the gov't response to the coronavirus macau's last covid- patient recovers, with no new cases for a month why did singapore have more coronavirus cases than hong kong? in: south china morning post another day of no new covid- cases in hong kong situation report- . world health organization the epidemiological characteristics of an outbreak of novel coronavirus diseases (covid- )-china demographic research and development foundation, inc. (drdf). covid- and the older filipino population: how many are at risk? uppi/ drdf research brief weekly assessment of the covid- pandemic and risk of importation-china population by-census impact assessment of non-pharmaceutical interventions against coronavirus disease and influenza in hong kong: an observational study. lancet public health the epidemiological characteristics of novel coronavirus diseases (covid- demographic science aids in understanding the spread and fatality rates of covid- death toll in uk care homes from coronavirus may be , , study estimates. financial times number of deaths in care homes notified to the care quality commission, england. in: office for national statistics mortality associated with covid- outbreaks in care homes: early international evidence. international longterm care policy network unimaginable human tragedy" in europe's care homes, says who. japan times guidelines for residential care homes for the elderly or persons with disabilities for the prevention of coronavirus disease (covid- ) (interim) online day care keeping elderly hongkongers active during isolation nursing homes in nations: a comparison between countries and settings how big is the problem in care homes? bbc office for national statistics kong ngo shows care homes they can stop keeping elderly in restraints. south china morning post the neglected health of international migrant workers in the covid- epidemic migrant workers in cramped gulf dorms fear infection current situation on migrant workers in dormitories-home thematic report: persons living in subdivided units tiny affordable housing in hong kong air and hygiene quality in crowded housing environments-a case study of subdivided units in hong kong a brief discussion on fire safety issues of subdivided housing units in hong kong social contacts and mixing patterns relevant to the spread of infectious diseases solidarity, ambivalence and multigenerational co-residence in hong kong. contemporary grandparenting: changing family relationships in global contexts living arrangements and older people's labor force participation in hong kong intergenerational co-residence during later life in europe and china level of underreporting including underdiagnosis before the first peak of covid- in various countries: preliminary retrospective results based on wavelets and estimating the extent of asymptomatic covid- and its potential for community transmission: systematic review and meta-analysis. medrxiv pathological findings of covid- associated with acute respiratory distress syndrome autopsy in suspected covid- cases case-fatality rate and characteristics of patients dying in relation to covid- in italy we would like to thank the academic editor and reviewers for their helpful and constructive suggestions. we would also like to thank professor stéphane helleringer for his comments on an earlier draft. the authors have declared that no competing interests exist. key: cord- - itwc tm authors: zhu, shuying; tao, jun; gao, huizhi; he, daihai title: age, source, and future risk of covid- infections in two settings of hong kong and singapore date: - - journal: bmc res notes doi: . /s - - -z sha: doc_id: cord_uid: itwc tm objective: to explore and compare the age, source and future risk of covid- infection in hong kong sar china and singapore as of march , . results: we find significant difference in age patterns of confirmed cases in these localities early in the pandemic. conclusion: we highlight the potential importance of population age structure in confirmed cases, which should be considered in evaluation of the effectiveness of control effort in different localities. the coronavirus disease (covid- ) pandemic first broke out in wuhan, china in december , and was declared as a global pandemic by the world health organization (who) on march [ ] . as of june , more than , , confirmed cases and approximately . % mortality were identified worldwide [ ] . the control experience in china showed that the isolation of infected persons, the tracking and quarantine of susceptible individuals, and other social distancing measures could contain this epidemic [ ] . singapore and hong kong are both praised as having taken "very effective" measures to intervene in the transmission of new coronavirus by a who official [ ] . as of march , there were cases in singapore and cases in hong kong. it seemed that there was no significant difference in these numbers given the fact that the measures adopted by singapore were not as strict as those adopted by hong kong but both cities were at high importation risk due to the high proportion of mainland chinese population flow. therefore, some media held the view that singapore adopted a plausibly proper but very effective strategy. in order to scientifically investigate the difference in the effectiveness of singapore and hong kong, we performed several statistical tests of the new coronavirus cases of singapore and hong kong in regard to their age distributions as of march . we found that the situation in singapore at this early point in the pandemic may have attributed to the relatively large proportion of infection in the younger generations of its population. however, no significant differences between the effectiveness of the measures adopted by hong kong and singapore government at this time period were noted. we obtained the data of the covid- cases of singapore and hong kong from singapore and hong kong's governmental websites [ , ] . the imported cases and local cases of both districts were studied separately. and we obtained the age structure data of hong kong and singapore separately from public websites as of march . in order to compare the difference of age distributions of the infected population and the effects of age structure. we performed the wilcoxon rank-sum test to compare the age distributions of the infected patients in hong kong with those in singapore. and then we divided age into age groups, and we counted the number of cases in each age group. we then used the wilcoxon rank-sum test to compare the difference of age-specific incidence between the populations. lastly, we obtained the agespecific incidence rate by dividing the number of cases in each age group by the population of that group and then compared the age-specific incidence rate by the chisquare test. from the onset of covid- to march , there have been imported cases in singapore and hong kong, respectively. the age distribution of imported and local cases can be seen in additional file : table s and figure s , which was similar to an epidemiological analysis using outsourced data in mainland china [ ] . considering that hong kong has a total population of . million and is more geographically close to mainland china, the risk of importing covid- cases should be higher than singapore which has a total population of . million and less pressure of population mobility with mainland china. results by wilcox test reported a significant difference in age patterns of both imported cases and local cases between the places, with hong kong taking up a higher percentage of elderly cases. nevertheless, this difference is no longer significant after the standardization of imported and local case numbers by each age category in hong kong and singapore respectively, shown in table and fig. . therefore, it is reasonable to assume that the variation in age distribution of the cases might arise from the age structure of the population per se. appropriate travel restrictions may delay the introduction of covid- infection. health authorities can provide advice or warnings to travelers. the formulation of the policy must weigh the potential serious economic consequences and the effect of the pandemic control. since the elderly are more vulnerable to get infected after exposure and develop into severe cases, thus the population age structure, among other factors, should be considered when comparing the effectiveness of control measure in different localities. the situations of covid- change fast worldwide. the covid- data of singapore with age information has been unavailable for public after we first submitted this work. hence, our work performed on merely the data of singapore and hong kong as of march . although the patterns of infected cases may stay similar to some extent, the age structures of infected cases in both locations may be different now. supplementary information accompanies this paper at https ://doi. org/ . /s - - -z. additional file : table s the cases of hong kong and singapore by march . figure s histogram of local/imported case numbers by age distribution in hk and singapore by march . covid- : coronavirus disease ; who: world health organization. who director-general's opening remarks at the media briefing on covid- - coronavirus disease (covid- ) pandemic how will country-based mitigation measures influence the course of the covid- epidemic? singapore for 'very effective' measures to suppress transmission of disease coronavirus: who escalates risk assessment of covid- to "very high"-as it happened covid- : cases in singapore early epidemiological analysis of the coronavirus disease outbreak based on crowdsourced data: a population-level observational study publisher's note springer nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations none. authors' contributions sz, jt, gh, dh conceived the study, carried out the analysis, discussed the results, drafted the first manuscript, critically read and revised the manuscript, and gave final approval for publication. all authors read and approved the final manuscript. council of hong kong and alibaba (china) co. ltd. collaborative research project (p ). the funding agencies had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; or decision to submit the manuscript for publication. all data and materials used in this work were publicly available. the ethical approval or individual consent was not applicable. not applicable. key: cord- - fgtjouu authors: hutton, thomas a title: service industries, globalization, and urban restructuring within the asia-pacific: new development trajectories and planning responses date: - - journal: prog plann doi: . /s - ( ) - sha: doc_id: cord_uid: fgtjouu while industralization programmes have been central to the development of asia-pacific states and city-regions over the past half-century, service industries are increasingly important as instruments of urban growth and change. the purpose of this paper is to establish service industries as increasingly significant aspects of urban development within the asia-pacific, and to propose a conceptual and analytical framework for scholarly investigation within this important research domain. to this end the paper explores a sequence of related themes and issues, concerning the larger developmental implications of urban services growth (or tertiarization), the facets of urban transformation associated with tertiarization, and a preliminary typology of urban service functions which acknowledges the rich diversity of service vocations and stages of development within the asia-pacific. the paper concludes that “advanced services”—specialized, intermediate service industries, advanced-technology services, and creative service industries—will be quite crucial to the development of city-regions within the asia-pacific, with respect to employment growth and human capital formation, to the urban economic (or export) base, to the operation of flexible production systems, and to competitive advantage. the development of these urban service poles will require innovative policy commitments and regulatory adjustments, as will the multi-centred specialized urban service corridors which function as engines of regional economic growth, and which provide platforms for national modernization and responses to the pressures (and opportunities) of globalization. to date, urban and regional development strategies for service industries within the asia-pacific have privileged globalization, industrial restructuring, and modernization aims, but there is also an encouraging record of more progressive planning experimentation in some jurisdictions, incorporating principles of sustainability and co-operative development. there is also increasing interest in policies to support cultural and creative industries among asia-pacific city-regions, informed by some recent urban policy experimentation in this domain. these experiences can offer models for further policy and programmatic innovation in the st century, as service industries continue to play larger roles in urban and regional development within the asia-pacific. introduction: service industries and urban transformation service industries have accounted for an increasing share of labour, output, and trade among the advanced economies of the organization for economic co-operation and development (oecd) over the last quarter century. this phenomenon of sustained growth in services (both in absolute and relative terms) can be observed at the national level among oecd member countries in terms of the changing composition of gross domestic product (gdp) and employment, but is especially pronounced at the urban or city-region scale. final demand service industries (for example retail, education, and most government services) are strongly tied to large metropolitan consumer markets, while intermediate services are even more spatially centralized, reflecting the influence of urban and agglomeration economies on the locational pattern of specialized, contact-intensive services. following the protracted decline of traditional manufacturing, service industries have led employment growth among most advanced city-regions over the last three decades. but the significance of service industries to urban (and especially metropolitan) development extends beyond measures of growth, as important as these are, to encompass comprehensive processes of change. at the broadest theoretical level we can discern intimate associations between service industries and redefining urban socio-economic processes and stylistic innovation over the past century. the growth of high-rise office complexes was an integral feature of the production of modernist urban landscapes, while advanced service industries have been central to the experiences of post-industrialism, flexible specialization, and post-modernism which have transformed urban landscapes, production sectors, and occupational structures over the past several decades. more particularly, service industries are directly involved in fundamental shifts in the urban economic base and industrial structure, but are also deeply implicated in the reconfiguration of regional structure, the metropolitan space-economy, and urban form. the rapid growth of service occupations among the most advanced post-industrial cities has also had profound implications for urban class structure and for the metropolitan social morphology, and is associated with the evolution of urban culture and even political preferences. in addition to these internal facets of urban transformation, service industries are also influential in the repositioning of cities and city-regions within external networks and systems. growth in urban service exports and trade may be significant in the recasting of city -hinterland relations, and in the reordering of national urban hierarchies, and is quite decisive in the emergence of global city-regions. at the apex of the global city hierarchy the most privileged status is associated with high concentrations of specialized banking and finance, and the projection of corporate power, as well as encompassing a more diversified ensemble of specialized service industries. these far-reaching aspects of urban service growth (or tertiarization) are most pronounced within the mature societies of europe and north america, but are increasingly relevant to an appreciation of urban growth and change within asia-pacific cities. the purpose of this paper is to propose a framework for investigating the influence of service industries on urban development within the asia-pacific, with an emphasis on dimensions of transformational change, both within the metropolis, and at the broader urban systems level. this entails an assessment of economic implications of tertiarization for cities and city-regions within the asia-pacific, including the emergence of new urban functions or vocations, and constituent shifts in the urban economic base, employment structure, and mix of industries. advanced or specialized services-especially, banking and finance, business and trade services, professional and 'informational' service activities, among others-are increasingly associated with modernization aspirations among the region's post-industrial, late-industrial and transitional societies, as reflected in development strategies and programmes. however, the parameters of urban change within the asia-pacific associated with tertiarization extend beyond this economic dimension to encompass impacts of service industry growth on urban structure and form, the built environment, social class and social morphology: i.e. the comprehensive facets of transformation (and re-imaging) of cities increasingly engaged in advanced services production, exchange, trade and consumption. our conceptual point of departure is that the expansion of services activity within asia-pacific cities and city-regions represents not only incremental urban growth and change, but, rather, consequential shifts in the role of urban areas within advanced production systems, in the globalization of trade flows, and in new social divisions of production labour. accordingly, the analytical focus will be on service industries and activities which the research literature has identified as 'propulsive' in urban growth and development; i.e. intermediate (rather than final demand) services, specialized service industries, and knowledge-and technology-based or informational services. at the same time, the record of urban services growth within the asia-pacific region discloses wide variations in stages of services development and mixes of service activity from place to place, and this variegation must be acknowledged in the interests of presenting a more rounded perspective on the experience than an exclusive discussion of leading edge examples would allow. indeed, some of the most interesting and instructive stories of urban tertiarization within the asia-pacific concern the juxtaposition of informal and advanced services in transitional societies, with ensuing social, land use, and planning conflicts. following this introduction, the paper offers a discussion of contrasts in developmental trajectories between the 'mature' atlantic core regions and those of the dynamic pacific core (chapter ), including an acknowledgement of industrialization as the dominant development paradigm for much of the asia-pacific since the s. defining elements of advanced urban tertiarization are identified, and are constituted within a taxonomy of global cities' service functions. the following section (chapter ) addresses both commonalities and contrasts in service industry developments among city-regions of the atlantic and pacific cores, and identifies five principal implications of service growth for urban change within the asia-pacific. these include the role of service industries in reshaping urban development trajectories, in the reconfiguration of urban space, and in urban social and cultural change, as well as the ramifications of accelerated tertiarization for the everyday experiences of city life and for urban identity and image. next, the paper offers a typology of urban services development within the asia-pacific (chapter ), derived from levels of services specialization as well as from urban scale. the spatial development of specialized services production within the asia-pacific is described, including both polarized patterns and more extended territories of tertiary sector growth, observed in the form of incipient urban corridors. these corridors (or clusters) represent a functionally specialized form of territorial development which exhibit features of co-operation as well as competition, and in part express policy responses to the pressures of globalization. the two final substantive chapters address planning issues and experiences associated with the development of the urban service sector. the first (chapter ) describes the basic evolution of local policy responses to urban tertiarization over the last quarter-century, from early development control policy regimes imposed to manage negative externalities of rapid service industry growth, to more balanced approaches, which combined developmental as well as regulatory elements. this chapter concludes with a set of important processes and events which have shaped a new policy environment for urban service industries in the early st century. next, chapter extends this discussion, by introducing a framework of six strategic urban policy models which are deployed in cities within the asia-pacific, including experiments in progressive planning (co-operative regional development, sustainable city-regions), as well as familiar models associated with globalization and restructuring objectives. the paper concludes with suggestions for a research agenda, emphasizing developmental and transformational implications of service industry growth for city-regions within the asia-pacific. there are of course different approaches to conceptualizing the units of 'world geography' apart from the standard continental divisions, as a spectrum of historical, socio-cultural, political and economic considerations can be imposed upon the standard geo-physical patterns. for much of the post-war period the idea of a tripartite structure of spheres organised crudely along ideological lines and developmental progress emerged as a descriptive convention, including a developed, essentially democratic-capitalistic 'first world', comprised of a hegemonic us bloc and its allies in north america, western europe, japan and australia; secondly, the comecon (council for mutual economic aid) group of nations, largely dominated by the ussr and concentrated within eastern europe and asia, but also including cuba; and, finally, a 'third world' of 'developing' countries, ostensibly non-aligned, but including many de facto client states of either the us or the ussr. with the collapse of the 'second' (comecon) world (comecon) world - , and the increasing pluralism within the first and third worlds implied in the post-modern viewpoint, there has been a renewed interest in (re) conceiving global geography or world regional patterns. in this regard lewis and wigen acknowledge the tendency of world regional frameworks "to grossly flatten the complexities of global geography", but assert that "some form of baseline heuristic scheme is necessary for teaching and thinking about metageography" (lewis and wigen, : ) . to this end their conceptual preference is to ignore political and ecological boundaries, and to instead focus upon historical processes, to give primacy to "the spatial contours of assemblages of ideas, practices, and social institutions that give human communities their distinction and coherence" (lewis and wigen, : ) , and to consider not only internal attributes but external relations. see martin w. lewis atlantic core, due in large part to earlier industrialization, and a longer record of tertiarization, but there is now a well-developed pattern of higher-echelon global cities within the asia-pacific (rimmer, ; preston, ) (fig. ) . these cities are centres of advanced industrial and services production, and are linked by capital flows, technology transfer, transportation and communication networks, and patterns of cultural exchange and diffusion, typifying aspects of international and global codependency. the second-order world cities achieve a level of global reach via the presence of certain specialized industry groups, propulsive firms, or influential international institutions, and thus comprise essential elements of the global economy. global city status is conventionally associated with comparative concentrations of intermediate banking and finance, headquarters of mncs, 'producer' services (stanback et al., ) and international gateway functions. however, increasingly global city status encompasses other suites of specialized service industries, including design, knowledge, and technology-based activities, in part reflecting scott's thesis concerning the transformational convergence of culture and urban economic development (scott, ) , as well as the competitive advantage of metropolitan cities for creative and informational services (table ) . this city-centred growth pattern is complemented by complex and distinctive forms of regional development, which include ( ) multi-centred urban growth corridors or 'megalopolitan' regions, such as the classic new york -new jersey conurbation (gottmann, ) , and the randstat urban corridor in the old atlantic core, and the example of the 'extended metropolitan regions ' (mcgee, ) of east asia and southeast asia, such as jakarta -bandung, beijing -tianjin, and tokyo -kawasaki -yokohama, within the asia-pacific sphere; ( ) 'lead regions' comprised of innovative industry complexes and propulsive firm networks, exemplified by baden -württemburg, the veneto, the ile de france, and the london-oxford -cambridge technology triangle within the old core (storper and salais, ) , and the kanto plain, orange county, and silicon valley (scott, ) within the pacific sphere; and ( ) incipient trans-border 'growth triangles' (and other geoeconomic constructs), illustrated by the singapore -johore -riau development triangle, and the cascadia metropolitan bio-region of the pacific north west, and, in the atlantic old core, the transmarche region, and the emerging baltic development zone which aspires to foster mutually beneficial development in northern germany, the former soviet baltic states of latvia, estonia and lithuania, and scandinavia. these new and emerging growth territories may exhibit positive spread effects of regional development generally lacking in less advanced zones table principal suites of specialized service industries for global city-regions i (suites of specialized service functions) banking and finance commercial, merchant, and investment banks; securities and brokerages; stock exchanges; non-depository financial institutions; insurance and re-insurance; industrial-commercial real estate and property development corporate control head offices of international and global corporations and multi-nationals; 'propulsive' corporations and firms producer services specialized, export-capable intermediate service industries and firms; corporate law and accounting firms; management consulting, consulting engineers gateway roles major international airports; major seaports; international telecommunications facilities capital functions national capitals; state/province/regional capitals and administration; offices of international agencies tourism and conventions international tourism and convention industries; major international fairs and expositions advanced-technology services software developers; it firms; internet providers; 'dot.com' firms creative services and applied design architects; industrial design; graphic artists/design; fashion design; interior design; landscape design education and knowledge major national and international universities and colleges; r&d operations and science parks; major 'think tanks' and other research/ knowledge-based institutions culture and heritage major museums and galleries; national libraries and archives; culturally defining heritage buildings, sites, and precincts of the global economy, and suggest possibilities of functional complementarity and reciprocal specialization, as well as the familiar exigencies of competitive advantage. in the aggregate, these characteristics-technology-intensive production, high quality economic infrastructure, productive human and social capital, superior external trade mechanisms and capacity, and the distinctive spatial patterns of growth described above -constitute defining aspects of development within the world's dominant economic spheres. these attributes affirm the exalted economic status of the mature atlantic core and the dynamic pacific core, define the trajectory of development at the leading edge of change and transformation, and suggest the power of convergence, interdependence, and hierarchy acknowledged as important facets of globalization. while important commonalities can be discerned, there are fundamental contrasts in the development experiences and transformational vectors of the atlantic and pacific spheres, as well as innumerable variations in the circumstances and growth paths of individual nations and regions within each of these dominant, supra-continental realms (see yeung and lo, ) . the inexhaustible differentiation of regional histories, political traditions and structures of governance, culture and geographical and environmental factors are seen to underpin the persistence of variegation and exceptionalism among regions and localities within both the old and new cores. the confluence of exogenous forces, including the rise of mnes, and increasing market integration and technological diffusion, has imposed some measure of developmental convergence and commonality across international space (as well as increasing disparities within urban social structures), but there are after all limits to the homogenizing effects of globalization, as the recent scholarly development literature attests. without denying the impressive global sweep of mnes and speculative capital, it is essential to acknowledge the significance of (largely) localized development influences, such as site and environment, the structures of social networks and civic institutions, and the quality of public policy and regulation. in an insightful book aimed at 'reasserting the power of the local', a number of scholars enrich the discourse on globalization by an elucidation of factors which reaffirm the power of local identity, and which provide some friction to the movement of capital and firms. storper, notably, asserts the significance of 'territorialization' in embedding some specialized forms of economic activity within specific locations, beyond the more generic considerations of urban agglomeration which can bind (especially contact-intensive) firms to central places, such as higher-order service enterprises which cluster within the corporate complex of the central business district (cbd). in this interpretation, a firm or activity is "fully territorialized when its economic viability is rooted in assets (including practices and relations) that are not available in many other places and that cannot be easily or rapidly created in places that lack them" (storper, : ) . this concept of territorialization can also incorporate the quality of civic institutions and civil society as influences on economic development and socio-economic welfare, as disclosed in putnam's seminal study of regional and community development in italy (putnam et al., ) . other important factors of locality that can influence differentiation in patterns of economic growth and development are exemplified by amenity attributes, which may include access to education and learning opportunities, and community levels of tolerance and equity, as well as air and water quality, leisure, and recreational opportunities. thus, the forces of globalization, as powerful and pervasive as they demonstrably are, may be significantly tempered, mitigated, or renegotiated at regional and local levels. this more nuanced interpretation of the interactions and tensions between global imperatives and local (or domestic) factors provides a useful backdrop for inquiry into the comparative developmental conditions between the atlantic and pacific cores, a task that has assumed greater importance both in the wake of the asia-pacific's dynamism over much of the past three decades, as well as the serious downturn that commenced in mid- in many east and southeast asian economies. this crisis, which delivered a major check to the continued growth and progress of many of the leading economies of the region, presents a complex set of economic, socio-cultural and political issues and underlying causes that vary widely from place to place, but certainly includes important structural factors (relating to governance, policy, regulation, and financial supervision), as well as more transitory or cyclical attributes (mcleod and garnaut, ). an apparent recovery process can be discerned in some of the asia-pacific economies, but the experience is likely to be protracted and wrenching for many, as the (now decade-long) recession in japan seems to attest. sustained recovery (and, more pointedly, a shift from growth to development) will require major adjustments to the political structures of asia-pacific states, as well as to the governance of corporations and industrial enterprises, and to the supervision and regulation of banks and financial institutions. both the depth and breadth of this economic downturn (and attendant social and political upheavals), and the quarter century or so of recurrent high growth levels that preceded it, raise questions concerning the contrasting trajectories of development within the mature atlantic economies and those of the new core of the pacific basin, as well as the factors underlying these patterns of differentiation. certainly one of the most salient and defining contrasts in the post-war trajectories of the atlantic and pacific spheres concerns the relative status and roles of the secondary (manufacturing) and tertiary (service) sectors, respectively, and the ensembles of policy, market and socio-demographic influences on these distinctive sectoral specializations. beyond the obvious reality that the leading states of both the pacific and atlantic spheres contain advanced industrial production sectors, and are experiencing growth in tertiary activity, it is important to acknowledge that while the growth of services represents a dominant motif of the economic and social reconstruction of western economies and societies, the accelerated growth of manufacturing industry and employment has been the principal story in the rise of the asia-pacific economies over the past four decades. among the mature economies of the oecd, concentrated within the old atlantic core, this same period has seen a massive contraction of production capacity and labour in basic industries, especially in fordist mass-production manufacturing, manifested most dramatically by wrenching processes of industrial decline (consisting mostly of outright factory closures but also some measure of locational decentralization) within long-established inner-city industrial precincts of large-and medium-size cities, and consequent losses of employment, income and revenue (noyelle and stanback, ) . new industries characterized by flexible specialization processes and technology-intensive outputs have emerged in 'lead regions' and 'new production spaces' (scott, ) within the atlantic core, so aggregate manufacturing output has held up or even increased (by value) in some areas (coffey, ) , but in general manufacturing activity has lost ground in relative terms in most oecd regions. over the past half-century, services have been essential features of the development of metropolitan cities (gottmann, ) . more specifically, intermediate services have emerged as increasingly strategic and propulsive elements of advanced production systems, as observed in successive rounds of industrial restructuring, in new divisions of labour, and in the rise of service-based global cities and new urban service poles (table ) . at the same time, the post-war period has seen among the most advanced societies the sustained expansion of service industries which (with related shifts in industrial production processes) have profoundly changed the economic base, industrial mix, labour force, land use and physical form of city-regions within the atlantic zone. service sector growth has thus constituted a central feature of economic restructuring among advanced nations and regions, with service-type occupations leading employment formation not only in the tertiary and quaternary (or informational) sectors, but also in manufacturing, where the growth of management, clerical, sales and technical workers has exceeded that for direct production workers and operatives in most cases. in general scholarly attention to the growth and development of service activities has evolved as follows: (a) an early interest in the growth of high-rise offices in the cbds of the largest metropolitan cities, including important theoretical and conceptual contributions (gottmann, ) , (b) a stream of empirical studies of office location, emphasizing regional policy implications and urban planning problems (daniels, ; goddard, ) , (c) growing interest in the social ramifications of services growth (bell, ) , (d) a sharper analytical focus on business, 'producer' and other intermediate services, and their role in urban and regional development (noyelle and stanback, ) , and in the operation of 'flexible' industrial regimes, (e) assessments of the global dimensions of services development, especially in banking and finance, as well as in producer services and communications (daniels, ), (f) acknowledgement of the importance of specialized services in the emergence of the 'informational city' and urban society (castells, ) , and (g) explorations of the intersections between tertiarization, occupational shifts, urban class (re)formation, and community-level impacts, especially in the metropolitan core (ley, ) . ( ) producer services as key to flexible specialization production regimes (coffey) ( ) emergence of integrated sevice-technology-production systems ( ) internalized service production ( ) externalized service production ( ) globalized service production ( ) but these structural consequences of tertiarization extend well beyond the economic dimension, as the sustained expansion of service labour (and concomitant decline in bluecollar workers) within the atlantic core regions has led in turn to the reformation of urban society, in terms of social class, community and neighbourhood patterns, culture, and political values and preferences, as documented in scholarly treatments of post-industrial society (summarized in table (a)). the tight spatial bonding of specialized, contactintensive service industries within intricate input -output relations has been instrumental in the reformation of urban structure and land use within the metropolitan core (gottmann, ; hutton and ley, ) . tertiarization has also generated more comprehensive changes in metropolitan structure, as seen principally in the emergence of specialized service nodes and clusters which dominate the space-economies of advanced city-regions, and also in urban form and the built environment, exemplified in the growth of the central city corporate complex, new districts of services production and consumption on the cbd fringe and inner city (including design and technology-based services), regional office and retail centres, and proto-urban forms which incorporate advanced service industries within 'edge cities' (garreau, ) (table (b)) . while tertiarization stands as the definitive and most consequential feature of economic growth and social change among western or atlantic nations and regions over the post-war period, industrialization has represented the principal development modality for much of the asia-pacific since the s and s. (although there have been to be sure important shifts in agriculture and other forms of primary and staple production in many pacific nations.) there is of course considerable variation in the temporal sequencing, specific industry emphasis, scale and stage of manufacturing growth among individual nations (and even among regions and sub-regions), but accelerated industrialization, supported in most cases by state policies and programmes, has been central to the expansion of every high growth asian-pacific state (douglass, ) , including ( ) the japanese ascendancy, seen in the industrial development of the japanese archipelago (especially within the principal conurbations of honshu but also including urban centres in kyushu and hokkaido) over much of the present century, with accelerated development of production in industrial and consumer goods from the s, including see garreau ( ) for an original contribution to our understanding of this spatial and socio-economic phenomenon. i am making a broad distinction here between economic systems in which manufacturing or (alternatively) services are dominant. it is of course possible to perceive services as 'industrial activities', as detailed divisions of 'service industries' are conventionally depicted within sectoral aggregations in standard industrial classification catalogues, for statistical purposes. moreover, there is a general preference for positioning service industries as co-dependent elements of integrated production systems (gershuny, ) . at the same time, industrialization as a development paradigm within the asia-pacific has certainly implied a powerful emphasis on the growth of manufacturing industries, industrial companies and conglomerates, factories and industrial labour, in the form of factory workers, assembly line employment, and operatives. jonathan rigg's analysis of modernization and development in southeast asia includes a special chapter addressing the idea (and reality) of 'the factory world' as a defining feature of this experience (rigg, : - ) . table defining attributes of advanced urban tertiarization defining conditions within highly tertiarized cities (a) urban industrial structure, economic base, employment and class sectoral/industrial structure tertiary sector larger than secondary sector; service industries growing faster than manufacturing industries both in relative and absolute terms industrial output services share of urban/regional gdp growing faster than manufacturing share market orientation/production linkages intermediate sector services growing faster than final demand services; specialized services and manufacturing co-dependent elements of advanced production systems urban economic base services comprise large and increasing share of urban economic base; significant and growing volume of specialized service exports and trade employment . % of urban employment in service industries occupational structure rapid growth of executives, managers, professionals; emerging social division of service labour favouring knowledge-and technology-based service workers, design, creative and cultural services urban class structure emerging hegemony of 'new middle class' (ley, ) of upper-tier service cohorts urban social morphology extensive social upgrading (gentrification) in older inner city neighbourhoods; growth of inner city loft housing and 'live-work'/'work-live' studios; increasing social displacement and inter-group tensions (b) urban spatial structure, space-economy, form, image and identity urban/metropolitan structure service industries dominant elements of urban core and (established or incipient) metropolitan sub-centres urban space-economy specialized service clusters and corridors dominant features of urban/ metropolitan space-economy (cbd corporate complex, seaports and airports, distribution centres, retail centres, higher education institutions, government and public administration, business parks, r&d parks] inner city landscapes new and emerging precincts of specialized services: applied design, creative and cultural services; internet providers and 'dot.com' firms; cultural centres; higher education; professional sports and entertainment; public recreation; live-work studios and new artist/artisan neighbourhoods urban form mix of modernist-post-modernist urban forms: high-rise office precincts in cbd and metro sub-centres, as well as new services domiciled in 'reconstructed' services production and consumption landscapes within inner city and inner suburbs; 'edge cities' and proto-urban forms on the metropolitan periphery infrastructure derived demand for transportation and other infrastructure associated with urban tertiarization identity post-industrialism; post-modernity image 'global' or 'world' city (hall, friedmann, sassen) ; 'informational city/society' (castells) ; 'transactional city' (gottmann) the expansion of global-scale industrial conglomerates and mncs; ( ) the origins of takeoff growth among the newly industrializing countries (nics), with accelerated industrialization initiated in taiwan and hong kong in the s, and singapore and south korea about a decade later (mcgee and lin, ) ; ( ) the later emergence of the 'threshold' or 'near' nics, notably malaysia and thailand, which retain important bases of agriculture and staple production outside the principal metropolitan zones, but which have experienced substantial manufacturing growth over the past two decades; ( ) the tumultuous growth and transformation of china, dating from the ideologically impelled industrialization programme enunciated in the series of -year economic plans commencing in the period - , to the industrial stimulus generated by the economic liberalization policies launched in , and then to the more recent expansion of advanced manufacturing in the lower yangtze, pearl river delta, and certain other coastal regions; ( ) the larger role played by industrial development in the transition of other populous agrarian nations, notably indonesia and the philippines; and ( ) the current economic restructuring programme in vietnam, associated with the 'doi moi' policy of economic and social renovation. in addition to these important examples, industrialization also represents a goal (or ideal) of lagging states within the region, such as laos, burma and north korea, although the realization of these industrial aspirations has been seriously impeded by a prejudicial mélange of factors including war, flawed development models, governmental corruption and administrative incompetence, lack of capital and other resources, and isolation. these national industrialization programmes and trajectories also featured important urban and regional dimensions. by the s, the asia-pacific sphere included a number of world-scale industrial metropoles, such as tokyo, nagoya, osaka, seoul, taipei, hong kong and shanghai, while by the s manufacturing emerged as an important feature of the metropolitan space-economies of southeast asian primate cities, including bangkok, jakarta, kuala lumpur, and manila (douglass, ) . beyond these large-scale urban industrial complexes, manufacturing activity increased within the metropolitan periphery, exurban areas, and even rural zones, for instance in the lower yangtze region, within the chinese special enterprise zones (sezs), within designated receptor areas (such as penang) for japanese foreign direct investment (fdi), and within desakota areas of east and southeast asia, proliferating the spatial milieux for industrial production in the region. even in pacific america, within which urban tertiarization processes are generally advanced, some city-regions have exhibited greater buoyancy in manufacturing than many of the older industrial cities of the great lakes region and eastern seaboard, within the broadly defined atlantic core. over the past two decades, los angeles, the san francisco bay area, seattle and even vancouver have experienced significant growth in advanced manufacturing such as aerospace and electronics (and in some basic production industries as well, such as garment production) within their regional territories, in contrast to the record of industrial decline in many other north american metropolitan areas, although to be sure they have also experienced high growth in service industries, and contractions in some traditional industries. at the end of the th century, then, industrialization represented the dominant trajectory for many states and regions within the asia-pacific, constituted a significant aspect of growth (together with specialized services) in some of the more advanced economies of the pacific realm, and remained an aspiration of lessdeveloped, agrarian and staple-dominated countries in the region. these industrialization trajectories will continue to be highly influential in the development of asia-pacific cityregions in the new century, but it is equally clear that service industries will emerge as increasingly significant features of urban growth and change, a theme we will explore in the following chapters. to date there has been relatively little scholarly attention paid to the development of service industries and employment within the asia-pacific, with the notable exception of case studies of cities within which services (especially advanced or 'higher-order' services) are playing significant roles (taylor and kwok, ) , and specialist studies of banking, finance and investment, and transportation and communications. the research emphasis has tended to be on multinational service corporations and international trade in services (waelbroeck et al., ; thrift, ; unctad, ; sieh-lee, ; lasserre and redding, ) , rather than on services development and associated issues for cities and city-regions. this situation reflects, to some extent, the pervasive influence of industrialization as a development paradigm within much of the pacific realm, emphasizing the primacy of manufacturing and industrial production within the growth trajectories of many asia-pacific states, regions and societies. the hegemony of the industrialization paradigm has created a kind of shadow effect within the scholarly literature on the economic development of the pacific basin, within which services are customarily treated as elements of the traditional urban retail or commercial sector, as essentially ancillary activities which can be effectively subsumed within industrialization processes and systems, or as special, almost aberrant features of exceptional cases such as hong kong and singapore. indeed, many of the region's leading service industries and corporations (notably banks, trading companies, and ocean freight lines) were established to facilitate manufacturing growth and the expansion of trade in goods, thus comprising essential features of the asia-pacific's industrialization experience. moreover, service industries, including modern, advanced services, are now sufficiently well-represented in a broad sampling of national and regional jurisdictions, and are now so increasingly central to the economic and social transformation of pacific cities, that a more incisive investigation of services growth trends and associated impacts is clearly merited (o'connor, ) . the centrepieces of urban service sectors within the asia-pacific are of course the large national and multinational service industry corporations, including the major banks and financial institutions (including brokerages and securities companies), trading houses, property firms, integrated construction and development corporations, and the leading airlines and hotel groups. these are, as is well known, highly concentrated within to illustrate, rigg's generally excellent and insightful treatment of 'modernization and development' in southeast asia offers only a single index reference to 'services' (and that one brief discussion in the text pertains to informal service activities), in the interest of focussing on the very important developments in agriculture and manufacturing, although modern service industries have certainly been instrumental to the growth of singapore, are of more than marginal significance to the development of malaysia and thailand, and are important features in the economic landscapes of the primate cities of southeast asian nations, including indonesia, the philippines and vietnam. the region's first-and second-tier global cities, especially tokyo, osaka, seoul, taipei, hong kong, singapore, los angeles, san francisco, and sydney. many of these financial corporations and other large service enterprises have become extensively globalized, enhancing the status of the cities within which they are domiciled; but a significant proportion of these corporations have been seriously damaged by the events of and after, and there have already been a number of major bankruptcies, with, no doubt, more to follow. the corporate power of cities within the asia-pacific is therefore pervasive, but by no means immutable. at a smaller scale, we can identify the full range of intermediate or producer services which, as in the mature economies of the atlantic sphere, typically include corporate legal firms and accountancies, management consulting firms, public relations and personnel companies, technical service operations, as well as planning and architectural firms which cater wholly or in part to the corporate sector. at the vanguard of growth and change there are also an expanding number of firms in the computer software and knowledge industry groups that are so crucial to the progress of advanced, information-based economies. in general, however, this intermediate services subsector (comprised mainly of small-and medium-size firms) is somewhat less well-developed in asia than is the case among the leading regional and national economies of europe and north america, where the producer services are seen as essential to the efficient operation of flexible production regimes, and have constituted the most dynamic elements of these economies and labour forces over the past two decades. this disparity is reflected in the large balance of trade deficits in specialized services incurred by most pacific asian nations (daniels and o'connor, ) . we can provisionally attribute the (relatively) less developed nature of intermediate services within the asia-pacific to a number of factors and conditions, including the perhaps obvious observation that services are generally at a less mature stage than among the more advanced atlantic core economies. however, there are also important structural factors as well. these include, notably, contrasts in the regulatory conditions and legal and contractual regimes between countries, which impose different kinds and levels of requirements upon firms domiciled within these jurisdictions. within many of the western societies these regulatory and legal regimes have become exceedingly complex and demanding, giving rise to specialized intermediate service firms which provide expert advice to corporations on a subcontracting basis, as the demand arises. within the asian realm, as we have already noted, many of these specialized service inputs are generated either internally within the corporation, as is the case with some of the larger korean and japanese conglomerates; or, as is the practice in many firms in china and southeast asia, are supplied by a network of advisors defined by kinship and social relations. moreover, there has been a substantial (if spatially and temporally uneven) growth of producer services within the asia-pacific, reflecting "the wide socio-cultural heterogeneity in this region and the distance between trade centres" (ho, : ) . at the leading edge of change among a growing number of asia-pacific societies, the implications of service industry growth may at least selectively reflect the experience of the mature economies of the atlantic-centred core, within which specialized service industries ( ) represent both agents and outcomes of economic restructuring, as well as leading elements of overall urban and regional transformation; ( ) constitute (with technology and manufacturing) co-dependent elements of advanced, flexible production systems; ( ) are associated with important, and in some cases defining, new divisions of labour and social class reformation; ( ) reflect, in part, increasing income levels and consumption rates within host societies; and ( ) have become significant elements of inter-regional and international trade flows, reflecting inter alia externalization tendencies and aspects of competitive advantage for specialized services production, export, and trade. as observed among the mature industrial (or post-industrial) societies of the atlantic sphere, too, service industries within the asia-pacific tend not to be distributed evenly across national territories, but are instead concentrated within urban regions, reflecting the spatial association between consumer services and their residentiary markets, and the even more centralized patterns of highly agglomerative intermediate (or producer) services. there is also a tendency toward greater levels of specialization in services production among larger cities, although there are to be sure some notable exceptions to this. this correlation between tertiarization levels, growth rates and degrees of specialization is of course most easily observed among the region's major corporate centres, such as tokyo, hong kong, and singapore, but the familiar spatial manifestations of service industry growth (cbds, corporate complexes, commercial strips and nodes, and the like) are features of a growing roster of asia-pacific cityregions, although their specific form may be locally distinctive. the study of specialized service industries within the asia-pacific, then, as in the atlantic sphere, necessarily implies an urban emphasis. these important commonalities notwithstanding, even at the most generalized level of analysis we can readily identify some defining distinctions between current services growth rates, development patterns and interdependencies within the new core of the asia-pacific, and those observed within the atlantic-centred old core. as in other facets of urban development, it is essential to achieve an appreciation of signifying contrasts in urbanization experiences in the asia-pacific, as distinct from the patterns of urban development within the atlantic core (lin, ) . these contrasts include the following: . generally higher growth rates of service industries and employment among asia-pacific nations and city-regions over the past decade and a half, reflecting more incipient stages of tertiarization in many asian jurisdictions and, broadly, more buoyant economic conditions over the past two decades or so. by way of contrast, service growth in europe has been (as daniels notes) slow or even stagnant (daniels, ) . (it must, however, be acknowledged that the depressed condition of certain asian currencies and financial markets are diminishing growth expectations in financial and service sectors among certain business centres over the short-to medium-term, and ensuing political instability and social unrest will almost inevitably exacerbate those impacts. moreover, urban service sector growth rates will inevitably slow among advanced cities with high existing levels of services labour, including singapore, hong kong, and japanese cities). asia-pacific city-regions, which represent in many cases significant departures from the more linear patterns of service industry growth common to the old atlantic-centred core. these contrasting tertiarization trends and processes are in part a consequence of the widely varying stages of overall development among specific national and regional jurisdictions, but are also associated with important (and in some cases decisive) policy factors and local development strategies. . the diversity of services-production linkage patterns among asia-pacific economies, which to some extent may follow the services externalization and subcontracting processes widely documented among european and north american firms, but are also exemplified in other respects by the distinctive nature of industrial organization in 'lead' asian economies in which large integrated corporations (keiretsu in japan, the chaebol in south korea) maintain internalized service supply; by the intricate entrepreneurial networks based on kinship relationships in parts of east and southeast asia (hsing, ) ; and by the intimate spatial linkages between industrial production and service providers observed in exurban or countryside production regimes in certain regions of china (marton, ) . . variation in the reconfiguration of metropolitan space-economies to accommodate the introduction of new, specialized service industry nodes and clusters, which follow to some extent the locational tendencies of services in advanced economies and city-regions; while at the same time exhibiting persistent spatial patterns derived from more traditional systems of urban and regional economic development, as exemplified in the desakota areas of southeast asia and japan, and, at a smaller scale, the intimate juxtaposition of advanced and informal service activities in central areas of developing societies (leaf, ) . in the most advanced cases, new spatial patterns of specialized services production include clusters of design, creative services, and advanced-technology service industries within reconstructed inner city precincts. . distinctive divisions of labour within urban service industries, which may appear to mimic the western model at the apex of the occupational hierarchy (i.e., the growth of managers, professionals, knowledge-based and advanced-technology workers), but also display substantial variation, derived in large part from localized culture, class structures and traditions, the pre-existing base of service workers, and region-based entrepreneurial or mercantile cultures. to these broad points of contrast in the tertiarization experiences of the asia-pacific and atlantic spheres, it is essential to highlight important differences in policy approaches and roles. within the asia-pacific, we observe a spectrum of (sometimes quite assertive and even grandiose) developmental policies and programmes designed wholly or in part to promote the growth of specialized service industries. these include the highly dirigiste approaches of japan (shapira et al., ) and singapore (ho, ) , within which central governments have assigned leading roles to advanced service industries in support of urban and national economic transformation, and enhanced roles for service industries in local economic development strategies and policies. in contrast, public policy approaches toward services among western societies have tended to emphasize regulation, including zoning, development control, and growth management, in addition to mostly episodic experiments with developmental policies, and only very exceptional attempts to undertake service industry 'megaprojects' on the heroic scale of numerous asian cities. although there are profound differences in stages and levels of tertiarization among asia-pacific city-regions, as we shall shortly see, the implications of urban service industry growth can be structured within five broad categories: ( ) a set of essentially propulsive and transformational impacts, within which services (especially advanced intermediate and knowledge-based service industries and institutions) are assigned leading roles in urban, regional and even national development; ( ) the (direct and indirect) impact of services on the internal restructuring and reconfiguration of the city-region, including regional structure, the metropolitan space-economy, and built form; ( ) services and the reformation of urban class and the city's social morphology (or ecology); ( ) implications of rapid tertiarization for the experiences of everyday life; and ( ) the role of services in the transformation of the city's image and identity. it must be emphasized that these are by no means neatly compartmentalized, discrete categories of consequence, however, as there are innumerable interactions and interdependencies between and among them. first, rapid tertiarization may have the potential to significantly accelerate the processes of urban growth and change, and to quite fundamentally modify basic urban economic functions or vocations, as reflected in the recomposition of the metropolitan industrial structure, economic base, and regional gdp. at one level, this process evokes the idea of post-industrialism, which positions service industries and occupations as ascendant features of the urban economy in a context of (relative or even absolute) contractions in basic manufacturing. however, in the asia-pacific setting the growth of specialized services can be seen as a concomitant element of advanced production systems, national modernization programmes, and globalization strategies of central and regional governments. these strategic aspirations are by no means fully realized, but they do underscore the importance of advanced services to the future development of the region. as is well known, tertiarization within many asia-pacific city-regions is impelled both by market and policy factors. this latter tendency is particularly marked in the region, as we can instance numerous examples of assertive public policy efforts both at central and local government and administrative levels designed to accelerate tertiarization (and/or deploy tertiarization as an instrument of broader economic and socio-economic transformation). examples of the deployment of policies for services in the interests of supporting or promoting transformational change include (a) synergies between national economic liberalization policies and local development strategies which have accelerated tertiarization processes (including advanced services) among designated chinese cityregions, (b) intersections between national industrial policies and urban economic programmes which have supported specialized service functions among japanese metropolitan cities, (c) ensembles of national development programmes and regulatory adjustments designed to enhance the growth of advanced, export-oriented services, as in the case of singapore since the mid- s, (d) central government support for strategic service industries as instruments of national development, accompanied by complementary local land use initiatives, as in the case of finance, producer services and information technology in malaysia, and (e) the more episodic (or less committed) support for service industries within (often somewhat schizophrenic) clusters of local development and growth management plans in sydney, melbourne, seattle, san francisco, vancouver, among other cities. the second category of urban tertiarization impacts concerns the role of services in change within the internal form and structure of the metropolis or city-region, and reflects the profound and comprehensive impacts of service industry development on the spaceeconomy of the contemporary city. the internal reordering of metropolitan space associated with rapid service industry growth incorporates processes which are multifaceted and interdependent: demand for services generates growth among service industries and firms to create a new sectoral mix within the city's economic base, and new patterns of services production and consumption as observed in the emergence of high-rise office complexes, secondary business centres, specialized service clusters (for example tertiary education and medical complexes), and new retail landscapes. these developments have visibly reconstructed urban structure and form in many american cities, but in some european cities have been situated more carefully within older districts, creating a more subtle and complex urban form, while in asia (for example in shanghai and osaka), preservation has been subordinated to the imperatives of accelerated restructuring, and has been in policy terms an afterthought at best. while market forces have constituted agents of urban respatialization, public authorities have deployed services as instruments of internal metropolitan reconfiguration within the asia-pacific, as in (a) the construction of new financial and corporate this urban 'policy schizophrenia' is associated, typically, with institutional conventions and operational practice within city and metropolitan governments. in most cases the urban 'plan' is prepared by staff planners, with input from other professionals and the broader community, and often emphasizes regulation, in terms of statutory development control functions and instruments (such as zoning, developing by-laws, and land use policies) and modern growth management modalities. by way of contrast, local economic development strategies are formulated by separate economic advisory groups, business interests, community groups and ngos, or special council committees or bodies appointed by (and accountable specifically to) the mayor or council chair, and are therefore often informed by quite different (and even oppositional) values and visions. a principal motivation behind the development of the la défence corporate complex was to protect the historic built environment of central paris from the kind of massive demolition and displacement impelled by office development in many other cities, by initiating a new 'cbd' outside the metropolitan core. this has been to a large extent realized (apart from exceptions such as the maine-montparnasse office-tower on the rive gauche), but the preservation of buildings and streetscapes in the central core of paris has been a series of struggles over the past century and a half (sutcliffe, ) . complexes, both to accelerate economic restructuring at the local level, and to support national modernization goals (as exemplified by the massive pudong project across the huangpu river from the established central district of shanghai) (yeh, ) , (b) the development of modern commercial and telecommunications infrastructure to support future world city aspirations (as seen in kuala lumpur), (c) the promotion of specialized financial and producer services in established cbds and designated subcentres to support world city status, and to maximize regional competitive advantage (with singapore presenting a vivid example), (d) the reclamation of land resources for accommodating the expansion of spatially or topographically constrained cbds (hong kong), and (e) the development of commercial and business megaprojects to diversify local economies, advance international business and financial relationships, and compete more effectively against other (often larger) centres within regional settings (as is the case with the minato mirai project in yokohama) (hutton, ) . more generically, public authorities also respond to infrastructure demand (for example airports and transit systems) derived from growth in services industries and activities (daniels, ) . the growth of service industries and occupations within asia-pacific city-regions also has important social implications, representing a third major set of urban tertiarization impacts. here, the growth of (especially advanced) service industries and related occupational cohorts generates an increasingly tertiarized labour force, which daniel bell described as a pre-condition for the emergence of a post-industrial society, over a quarter century ago (bell, ) : a contested idea, to be sure (gershuny, ) , but a seminal and prescient contribution in many ways. within the highly tertiarized city, the growth of specialized services leads to significant socio-spatial effects, including the familiar pattern of social upgrading within inner city neighbourhoods, and the formation of new suburban communities comprised largely of service workers, but also the recent emergence of a 'new middle class' of higher-echelon service labour (ley, ) . the rise of this new middle class of elite service workers (professionals, executives and managers, entrepreneurs and creative services occupations) as a presence in the inner city, a larger process than earlier, more incremental experiences of gentrification, comprises individuals who view the metropolitan core as a place to work, live, and recreate, leading to the transformation of the central city with respect to structure, land use, form, and lifestyles. there are also broader cultural connotations associated with the new middle class, as seen in shifts in tastes, values, behaviours, and even political affiliation. this new middle class enjoys a hegemonic status within the most highly tertiarized cities in the region, such as vancouver, seattle, san francisco, and sydney, and comprises the ascendant social cohort within singapore, tokyo, and hong kong, but is also observed as a growing presence (with some local variation in specific features) within the central districts of seoul, shanghai, guangzhou, and kuala lumpur, among other cities. the fourth set of impacts of service industry growth within cities of the asia-pacific concerns changes at the micro-level, what braudel termed the 'structures of everyday life' (braudel, ) . although much of the scholarly analysis of tertiarization has emphasized change within the three strategic categories described earlier, a more nuanced appreciation of the more intensely localized implications of growth in services is essential to attaining an appropriately rounded profile of the process. these include, for the purposes of illustration, the impact of service industries and the growth of service occupations on the quality of working life, and on localized displacement and dislocation at the neighbourhood and household levels (chua, (chua, , , especially within a context of industrial decline or restructuring. there is considerable potential for research on the important gender aspects of tertiarization, which may include the tendency for over-representation of females within many service occupations and industries. within the highly tertiarized societies of the old atlantic core, the past several decades have seen both the impressive progress of women within some of the credentialized service occupations, for example in law, accountancy, and planning, but also a more discouraging tendency for women to congregate in more menial, poorly paid and distinctly marginalized positions. there are also important linkages between the growth of service industries in asia-pacific cities and international migration. australian scholars have suggested that immigration can enhance the 'productive diversity' of economies, and more specifically that skilled immigrant professionals can support urban services exports, for example in sharing or transferring within the firm knowledge about overseas markets (aislabee et al., ) . lin observes that characteristics of mobility, flexibility and entrepreneurial skills are defining attributes of hong kong migrants (lin, : ) , enhancing their attractiveness to receiving urban societies and business communities. in certain cities, recent immigrants are over-represented both within entrepreneurial and management occupations, but also among more menial service occupations; this is especially the case in large global cities (sassen, ) . again, as in other facets of tertiarization, we can discern within asian labour markets some powerful resonances of trends initially observed in mature cities of the atlantic core, but there are also quite distinctive, persistent traditional socio-cultural contexts to consider. the importance of maintaining a perspective on the more localized implications of tertiarization also acknowledges the reality that the expansion of service industries by no means involves just the formal business, professional and managerial activities that have led growth among the western urban economies, but also the full range of neighbourhood shops and markets, casual restaurants and bars, and personal and retail services (to say nothing of other service establishments that may operate on, or even over, the margins of legality and social acceptance). in many asian cities, these smaller scale service operations may be viewed as an extension of the traditional population of informal service workers (itself a contested term), service activities which occupy the urban interstices between the more formal corporate business and retail structures. these can be seen as persistent features of the central city, not only among the megacities of southeast asia, such as bangkok and jakarta, but also within the downtown spaces of modern world cities such as tokyo. they are not simply residual activities, but essential, if often undervalued, operations that support the more formal service economy in different ways within the metropolitan core, including the provision of food and beverages (yasmeen, ) . these small-scale, low-return service firms survive by virtue of entrepreneurship, reliability, thrift, and knowledge of where the commercial niches exist in the modern city, and they contribute to the vitality and identity of the urban place. a final aspect of urban transformation associated with tertiarization is derived from an accumulation of the changes described earlier-economic, social, cultural, physical, and spatial-and is commonly articulated as a metamorphosis of the city's character, as perceived by citizens (constructed as 'identity') or as reconstructed by government and corporate entities and external agencies ('image'). the perceived image of a city can be substantially altered by comprehensive processes of tertiarization, as seen in the repositioning of singapore and hong kong as post-industrial, specialized service centres, although usage of decidedly obsolete nomenclature such as 'newly industrializing economies' is surprisingly persistent, as are outdated tropes like 'little dragons' or 'little tigers' (cartier, ) . in some cases national governments have supported specialized service industry projects as quite deliberate instruments of urban re-imaging, as seen in the creation of international banking and producer services in the pudong development in shanghai, and in the construction of the petronas towers in the central area of kuala lumpur. these initiatives are designed in part to underscore a commitment to modernity, and by extension to symbolize national economic progress and aspirations to global status and engagement, but also to supplant traditional (or, more pejoratively, 'backward') industries and related social groups. these more grandiose visions can be contested, especially where the elite beneficiaries of advanced service industry growth (for example professionals and managers in financial and business services, as well as cronies of rulers and oligarchs) represent a particularly visible and privileged expression of dichotomous 'development' as set against the condition of the urban masses in places like jakarta and manila. the issue of urban identity may also be deeply problematic, as the rapid growth of services elites within asian-pacific cities can presage decisive shifts in power relations (political as well as economic) within the urban community. in some cases the ascendancy of upper-tier service workers represents a new socio-economic and socio-political hegemony, implying a coincident subordination of traditional industrialsector cohorts, as well as an exacerbation of income disparities. as in other aspects of urban tertiarization within the asia-pacific, contrasts in scale and stages of development are significant, as are tendencies toward exceptionalism when case studies are subjected to closer analysis. thus, baum concluded that the sustained growth of specialized service industries, advanced-technology activities and related occupations in singapore, coupled with comprehensive public housing programmes and education investments, has resulted in a predominantly professionalized (as opposed to polarized) occupational and social structure within the city-state (baum, ) . in hong kong, where specialized services have also driven urban growth and socio-economic change (kwok, ) , the post-colonial record since includes growing poverty (about residents earn less than $ per month), attributable in some part to the inadequacies of the secondary school system, a situation which one legislator fears may lead to 'serious social instability' (lee cheuk-yan, quoted in far eastern economic review: october ). at a larger scale, a combination of market liberalization and selective tertiarization in certain chinese cities, with attendant political and bureaucratic corruption, has generated income polarization rates approaching or even exceeding the american level. this striving for new urban identities in the chinese case, with its repressed tensions and conflicts, can be seen in the shanghai government's preference for 'high class' individuals (well-educated, with the right attitudes, outlooks and professional profiles) for the glittering new towers of the pudong project (halliday, ) , a far cry indeed from the earlier communist exaltation of the urban industrial worker and fraternal colleagues in the pla and in rural peasant communes. we can also discern highly localized intersections of globalization and tertiarization in the reconstruction of identity at the district level. the proliferation of transnational retail and food services within commercial complexes is of course a ubiquitous phenomenon, as observed in places like shinkjuku and shibuya stations (and commercial subcentres) in tokyo. in hong kong, the incursion of service industry commuters in the new territories has transformed the social identity of certain of the post-war industrial communities, as seen in the transformation of tsuen wan from 'hakka enclave' to 'post-industrial city' (johnson, n.d.) . in the case of singapore, the last decade has seen the demise of the kampung kopi-tiam (informal eating places, serving authentic local fare) as a result of relentless modernization (chua, ) , and the almost total disappearance of traditional rural life, while other local retail and shopping districts have been subject to the reformation of identity associated with the tastes and behavioural preferences of affluent expatriate populations. chang deploys the term 'expatriatization' to describe a "spatial transformation in which land use increasingly reflects an expatriate bias", as typified in holland village, a local commercial centre within an affluent residential district of singapore, but one which "reflects the influence and influx of global cultures" (chang, : ) . in the most highly tertiarized cities within the asia-pacific, exemplified by san francisco, seattle, vancouver, sydney and singapore, a distinctive urban profile associated with dominant service industries and occupations within the financial and producer services now incorporates a more recent overlay of technology specialists, notably internet providers, software developers, and the so-called 'dot.com' firms. many of these firms have been concentrated within "new service production landscapes" within or proximate to the central area, exemplified by 'silicon alley' and telok ayer in singapore, yaletown in vancouver, belltown in seattle, and the northeast mission and south park districts of san francisco (hutton, ) . these technology-based service firms (which also include graphic designers, who exemplify the production synergies of technology and culture in applied design) typically exhibit employment structures dominated by young entrepreneurs and 'techies', with distinctive skills and lifestyles, underscoring both the new social divisions of labour in the urban service sector, and the highly volatile nature of urban identity in the post-modern, globalized metropolitan order. over the last years, the number of these technology-intensive firms within inner city production districts has contracted significantly, as part of the crash of the dot.coms. however, new survey research has disclosed the emergence of 'hybridized' firms combining creativity and technology toward the production of high-value goods and services, signifying a new phase of development within the metropolitan core of advanced societies (hutton, ) . these trends therefore demonstrate both the volatile nature of recent phases of service industry development, as evidenced by the accelerated processes of transition and succession, as well as the distinctive role of the inner city as site of innovation. stages of urban service industry development within the asia-pacific the preceding narrative described important distinctions in the broader tertiarization experiences as observed within the old atlantic core and the new core of the pacific realm. at the same time, there are also quite profound differences in stages or levels of service industry development among (and within) asia-pacific nations, just as there are important contrasts in levels and rates of industrialization. the construction of typologies of urban tertiarization among asia-pacific city-regions is hampered by data constraints and conceptual problems, and more recently by the shortterm impacts of the crisis of currencies and financial markets of and afterwards. although this crisis was seen to depress prospects for the asia-pacific generally, the impacts have been spatially quite uneven, and as the fiscal-economic malaise spread within the regions of the asia-pacific, and within social and political domains, it is by no means beyond the realm of possibility that the medium-to long-term outlook for certain urban centres has been seriously compromised. thus, to the overall perception of dynamism among the urban service sectors and industries of the pacific region, we must add considerable uncertainty. there is also a clear need at the outset to acknowledge the increasing complexity of overall urban development patterns, within which (we are arguing in this paper) service industries are increasingly playing larger roles. to illustrate, terry mcgee, in a retrospective paper on his concept of 'the southeast asian city' published in following years of extensive fieldwork, observed that "while urbanization levels will continue to rise there will be much differentiation between countries which will make the construction of any one model of the southeast asian city impossible" (mcgee, : ) . in this interpretation, models (or typologies) cannot reasonably function as templates of "supposedly universalizing tendencies" (mcgee, : ) , but rather should reflect the importance of specificity and exceptionalism in urban development experiences. it may at least, however, be possible to structure a basic and highly simplified typology of tertiarization stages among representative classes of asia-pacific city-regions, as a means of gaining insights into the range of urban tertiarization trajectories, the nature of specialization in services among city-regions, and the association between service development and urban hierarchy in the region. here, a typology of urban service centres within the region, while inevitably masking considerable nuance, may at least serve to depict some basic features of functional differentiation. while tertiarization stages and levels vary widely among asia-pacific city-regions, service industries are certainly performing significant roles in urban growth and development across a range of city types and urban scales. there is by no means a strict correlation between urban rank-order and level of service industry specialization within the asia-pacific region. to illustrate, there are medium-size cities with considerable global reach in terms of corporate power and important specializations in strategic service industries, such as finance and information technology (notably singapore and seattle), while a number of mega-urban regions (for example jakarta and manila; see mcgee and robinson ( ) ) contain limited advanced services capacity relative to their overall urban scale. therefore, a typology of cities engaged in specialized services production and trade should incorporate 'suites' of services specialization and developmental progression, as well as attributes of scale and hierarchy. accordingly, table positions asia-pacific cities and settlements within seven principal categories of specialized tertiary activities, distributed spatially within urban clusters, corridors, or 'outposts' within the western and eastern littorals of the pacific basin (depicted cartographically in fig. ) . at the peak of the pacific urban hierarchy we find tokyo and los angeles, the dominant corporate control centres within this extensive economic and trading zone. these massive city-regions contain to be sure huge concentrations of manufacturing, and, indeed, exhibit greater industrial strength than many of the first order global cities of the atlantic realm, such as london, paris, and new york. both tokyo and los angeles have important, global scale advanced-technology industrial sectors, situated within their metropolitan and immediately proximate territories, including orange county (in the case of los angeles) (scott, ) , and the new production spaces of the tokyo metropolitan region (tmr) (fujita and hill, ) . however, while both tokyo and los angeles retain an impressive base of modern manufacturing capacity, their most insistent claim to global city status rests on their downtown complexes of international banking and finance, and headquarters of mncs, supported by highly specialized producer services and superior international communications systems and transportation networks. los angeles and tokyo are also global centres of cultural production and dissemination, media concentration, and applied design and creative industries. they contain major universities of high international standing, including ucla and usc (los angeles), and tokyo university and waseda within the japanese capital. of these two pacific regional first-tier global cities, tokyo has conventionally been ranked as the leading centre, in view of its base of multinational head offices, and more particularly, its concentration of major banks, securities firms and trading companies, but this status may need to be reconsidered in light of the fall-out from the crisis (and, indeed, the failure to effectively address structural and institutional problems in the national banking and financial sector over the last decade). tokyo has considerable underlying industrial and overall economic power, but there is certainly the prospect of serious erosion in its financial sector over the mediumterm at least, which may jeopardize its position within the triumvirate of highest-order world centres (which also includes london and new york). fig. . asia-pacific urban service centres: hierarchy and specialization. doel and beaverstock ( ) observe that despite the claims and assumptions of fully globalized capital markets, the asian financial crisis has had relatively little negative impact on london and new york banks and financial corporations. indeed, many of the european and north american investment banks, for example, have (at least quietly) rejoiced in the misfortunes of the japanese banks in particular, as the asian financial crisis has (at least for the moment) 'seen off' their japanese competitors. category within our provisional typology includes six second-tier global cities: hong kong, singapore, seoul, osaka, san francisco, and sydney. despite significant contrasts in urban scale (to illustrate, there is seoul with a population of over million; and singapore at million), each represents a major asia-pacific financial, corporate and business centre. they are all characterized by ( ) very large cbd corporate complexes of head offices, multinationals, international banking and financial activity and producer services; ( ) strategic gateway functions and major international airports; ( ) major universities and knowledge-based institutions; ( ) large concentrations of executives, professionals, managers, entrepreneurs and other higher-order service occupations within the metropolitan labour force, and ( ) a powerful international corporate 'reach', competing in some sectors or areas with other second-(and even some first-) tier global cities. in each of these six asia-pacific financial and business centres, we also observe new precincts of specialized services within the inner city, including design and creative services, multimedia and post-production firms, internet providers and dot.com firms, reflecting the 'advanced tertiarization' stage of urban spatial development depicted in table this typology serves to highlight very broad variations in tertiarization levels among selected city-regions within apec, but even a cursory examination of individual cases discloses considerable variation in the trajectory of restructuring and service industry development within each category. for example, both singapore and hong kong specialize in advanced service industries, including finance and banking, producer and other high order services, tourism and convention activities, and higher education. each is now a major exporter of services; hong kong is ranked as the th leading exporter of services globally (hang seng bank, ) . manufacturing has declined from . % of hong kong's employment in , to only . % in , a level comparable to that of the most highly tertiarized atlantic core societies (asian development bank, ) . upper-tier service industry professionals, managers and entrepreneurs constitute the dominant social class in hong kong (kwok, ) . however, hong kong's emergence as a centre of specialized service production and trade has been impelled principally by an exceedingly liberal regulatory regime, while singapore's restructuring trajectory has been enhanced by a more direct application of policy measures. following a brief but sharp recession in , the singapore government resolved to transform the city-state from a branch-plant industrial enclave to a regional (and world) centre of tertiary production and trade, with the aim of becoming the 'switzerland of asia' by . this overarching economic development and transformation goal has been to a large extent realized, and singapore now represents a policy experience that other nations (notably china) are endeavouring to emulate. although hong kong's classically laissez-faire approach contrasts sharply with singapore's explicitly dirigiste development strategy, selective public policy initiatives have facilitated hong kong's economic restructuring. as observed by taylor and kwok ( ) , hong kong experienced an accelerated transformation process over three decades, from an 'industrial metropolis' (export manufacturing phase) in the s, to a 'postindustrial' status (information service phase) over the s, and emerging as an 'international metropolis' by the s. a sequence of policy and (especially) physical planning measures were deployed to promote economic transition and transformation, including the industrial new town programme of the s, the expansion of the hong kong cbd eastward toward wanchai and causeway bay in the s, and the recent investments in transportation infrastructure, as in the linking of hong kong with guangzhou by expressway, and the construction of the international airport at chek lap kok. there have also been substantial new public investments in tertiary education, training and housing, underscoring a substantial government commitment to upgrading the quality of hong kong's human resources and social capital. these investments and land use policy initiatives suggest that contrasts between singapore's and hong kong's approaches to economic transformation which insist on sharply dichotomous contrasts may be somewhat overstated, although the extent (and sustained commitment) of direct policy intervention in the singapore case is in many respects singular. our third category includes second-and third-tier global cities, which feature large and generally fast-growing service sectors, established on a base of world-scale manufacturing and industrial production capacity in each case. we can identify two sub-categories (table ) within this aggregation: first, three 'advanced' business and industrial centres (nagoya, kobe and taipei) situated within leading east asian economies; and secondly, a set of 'transitional' urban centres which still possess some features of early phase industrialization and a relatively large informal sector, including 'floating' or transient labour contingents (beijing, shanghai, guangzhou, bangkok, and kuala lumpur). however, each of these large cities exhibits relatively high growth in producer services, including engineering and business services. other defining attributes of these centres are ( ) important international gateway roles, ( ) major public and private sector investments in higher-order services infrastructure, and ( ) ambitious local/metropolitan strategies for new, specialized service industry roles and 'vocations', supported in most cases by national government policies and projects. the japanese experience of tertiarization provides particularly instructive case studies, in light of the priority accorded industrial development up to the s, the lead role of the central government and its constituent ministries over the last decade in assigning new development roles incorporating specialized service and technology-based industries for the major cities, and the outcomes of these initiatives among different japanese cities (edgington, ) . in general, the central government has been concerned both with the need to maintain a leading edge position in industrial production within the asia-pacific, while preparing the large cities for more advanced roles in specialized services industries, both for the domestic economy, and for trade purposes. much of the research on economic restructuring in japan has emphasized 'hard services,' notably technology, and its role in transforming both industrial production modes and urban economic structures (glasmeier, ) , while another major body of scholarship deals with the transformation of tokyo, while hong kong has initiated over the past years numerous specific projects and programmes to support the expansion of service industries, singapore has enunciated policies and programmes to promote strategic services (e.g. banking and finance, producer services, and it) within more formal policy statements and structures, consistent with the city-state's distinctive policy culture and administrative styles. the recent expansion of design and technology-based services in heritage districts outside the cbd represented one of the few 'spontaneous' (or unplanned) economic phenomena in the city-state's recent history (interview with urban redevelopment authority official, july ), although there is now policy support for cultural industries administered by the tourism development board. japan's first-order 'world city' (masai, ) . important themes concerned with tokyo's transformation include tensions and conflicts between the capital's international roles and local functions (fujita, ) , and the problems of accommodating (or, prospectively, relocating) central government functions from tokyo's metropolitan core (isomura, ) . however, there has also been some important work focusing on the restructuring (and, more specifically, tertiarization) of other principal japanese city-regions. these experiences include the economic restructuring of tokyo (machimura, ) , the expansion of advanced services such as finance, information services, and education in the major industrial city of nagoya over the last two decades (hayashi, ) , and the new emphasis on advanced knowledge-based service industries for the transition of yokohama from gateway port (and 'shadow city' for tokyo), to a more independent role as international business centre (edgington, ) . the experience of metropolitan transformation among the largest chinese city-regions over the past several decades represents a striking example of the influence of policy priorities within a command economy, and the potential for accelerated tertiarization following an adjustment of central government policy direction. following the industrialization policies and programmes of the period over the s, s, and s (including the ruinous 'great leap forward'), chinese cities "were endowed with a massive and diffuse manufacturing capacity, and provided with few incentives (until the last decade) to develop the services sector" (hamer, : ) . the economic policy reforms of (and more specifically) the mid- s embodied a recognition that modernization would require the more efficient deployment of cities and their resources, and thus heavy manufacturing was increasingly decentralized to outlying areas, and services (especially financial and producer services) were encouraged, both by economic planners in beijing, and by local authorities. in order to achieve growth in advanced production and transition to a more knowledge-based economy, hamer estimates that "up to % of the local labour force will have to be employed in the producer services sector" (hamer, : ) , a proportion that seems high even by the standard of more advanced oecd cities, but is perhaps nonetheless indicative of municipal aspirations. lin also underscores the crucial role of cities in the modernization of the chinese economy as represented by their concentrations of advanced service industries and occupations which enable higher levels of creativity, efficiency, and internationalization (lin, : - ) . recent trends in beijing, shanghai, and guangzhou serve both to generally underline the growing importance of service industries within the development trajectories of major chinese cities, while at the same time demonstrating the exceptionalism of specific cases. in beijing, an acknowledgement of the inappropriateness of the soviet-style heavy industrialization of the ancient capital, with its attendant environmental and displacement impacts, sets the stage for a new development strategy reasserting political, administrative and cultural roles. the goal of the - master plan (approved october ) is to develop the "historic city into a modern, economically prosperous and socially secure international metropolis of first class world standard in services, infrastructure and environmental quality" (mao and jin, : ) , representing an abrupt departure from the industrial city model of the s and s. as the contemporary beijing master plan invokes the re-establishment of the capital's traditional administrative and cultural roles, shanghai's current transformation recalls financial and trading functions de-emphasized following the ascendancy of the communists to power. immediately prior to the ascension of the chinese communist party in , shanghai's financial sector included foreign banks, private and government banks, trust companies, and currency exchangers: "with such a large number of financial institutions, representing a high degree of concentration of capital, shanghai was in a position to control the economy of the entire nation" (fung et al., : ) . a succession of five-year plans emphasized the primacy of manufacturing for shanghai's industrial transformation, with a particular emphasis on heavy industry and the production of capital goods. by the completion of the first five-year plan (in ), shanghai had experienced a transition from an outward-looking financial centre to the leading industrial centre of an almost autarkic chinese state. the economic policy reforms of the late s and mid- s presaged the onset of yet another fundamental change in economic priorities for shanghai, and, more specifically, for the reconstitution of shanghai's financial, trading and business service functions. to a considerable extent, this massive effort in economic restructuring is intended to offer china a strategic access to the global economy (yeh, ) , but (at least at a subtextual level) the question of achieving a competitive position vis-à-vis hong kong in financial and trade services must be acknowledged. in this respect, shanghai has certainly attracted an impressive quantity of investment in banking and commercial (and supporting public) infrastructure, as well as a growing number of mncs and mnes, but has not yet achieved the high concentrations of domestic and expatiate professional expertise in specialized services that is a defining hallmark of highest-order global cities. (indeed, as kris olds has observed, shanghai's globalization strategy has been highly dependent on the engagement of the 'global intelligence corps' of elite professionals; olds, ) . here, hong kong is likely to hold a competitive advantage over other chinese cities over the short to mediumterm by virtue of the territorialization (storper, ) of this expertise and specialized human capital. the two fundamental shifts in shanghai's development trajectory over the past several decades can be interpreted empirically. in , the 'tertiary sector' (i.e. commerce, finance, communications, science and technology, education and culture) constituted . % of shanghai's regional gdp. following years of investment in manufacturing capacity and employment, this proportion was reduced to only . % by . the intensive promotion of advanced service industries during the s resulted in an increase in the tertiary sector's share of gdp to % by , while shanghai's economic development strategy called for an increase in this proportion to about % by (fung et al., ) , led by the advanced services complex in the pudong redevelopment mega-project. (shanghai's service sector grew by % in , and by % in ; chreod ltd, ) overall, shanghai's experience of accelerated industrialization and subsequent re-tertiarization must represent one of the most dramatic episodes of economic restructuring among large metropolitan cities in the post-war period. guangzhou is, of course, smaller than beijing or shanghai, but it performs strategic gateway roles for guangdong province and southern china as a whole, and has undergone significant processes of restructuring and tertiarization (xu and yan, ) . as in other large chinese cities, economic policy priorities following entailed the transformation of guangzhou from a 'consumer city' to a 'producer city'. this strategy of large-scale industrialization was perhaps less fully realized than in the case of shanghai, because of the persistence of entrepreneurial traditions in the province, and guangzhou's distance from the national capital, which enabled at least a degree of autonomy. building on its well-established gateway and entrepôt functions, guangzhou was strategically positioned to immediately benefit from the opening up of chinese coastal cities. in the period - , growth in services exceeded that for agriculture or manufacturing, with lead tertiary sector industry groups including finance and corporate support services (nanjiang, ) . guangzhou is the urban centre for the pearl river delta economic region, which represents (with the lower yangtze region and southern fujian) major growth regions and access points for china to the broader asia-pacific and global markets (johnson, ) . the issue of whether guangzhou can extend its regional role more fully into the national realm remains an open question (tsang, ) , as are the 'terms of co-existence' with hong kong following the latter's post-colonial status as a special administrative region of the prc as of july . there is to be sure potential for complementarity as well as competition as characteristics of the relationship between guangzhou and hong kong within the pearl delta extended urban cluster, a theme to be addressed in more detail below, but over time guangzhou will aspire to greater shares of the region's international financial and business activity. the fourth aggregation of city-regions depicted in table comprises metropolitan areas characterized by the advanced tertiarization of the urban economy and labour force. this fourth category of asia-pacific cities includes two sub-groups: first, advanced, highly tertiarized cities with substantial manufacturing capacity and associated labour cohorts, and propulsive corporations, notably seattle, melbourne, and yokohama; and a larger contingent of specialized services cities with relatively modest industrial production sectors, including vancouver, portland, fukuoka, and brisbane. in many respect these jurisdictions embody features of service industry development observed within the mature urban and regional economies of the old atlantic core, which typically include (a) a dominant status for services within the metropolitan industrial mix, export base, and occupational structure; (b) the formation of corporate complexes within the cbd; (c) the emergence of new, creative services (culture, applied design, multimedia) on the cbd fringe and inner city; (d) the influence of suburban business centres and 'edge cities' in regional multinucleation; (e) intersections between services growth and changes in urban housing markets; and (f) the increasing role of services in the reformation of urban identity, politics, and lifestyles (ley and hutton, ) . at the same time, many of the city-regions within pacific america and australasia also exhibit tendencies common to other asia-pacific metropolitan areas, such as (relative) economic dynamism and higher growth rates in services, and are also linked to asia-pacific cities, markets and societies by increasingly diverse networks of trade, investment, immigration and travel. as a crucial intersection of two principal processes of urban development, large-scale immigration, especially from asian societies, has in important respects augmented urban tertiarization processes, reinforcing entrepreneurial, professional and management occupations, and contributing to export services trade by enhancing the connectivity between trading centres. we can therefore position these cities as geographically peripheral, but functionally integral, nodes of the asia-pacific urban system and as important examples of a distinctive stage of urban tertiarization within the pacific realm. the fifth category within our provisional typology of asia-pacific cities engaged in services production includes several southeast asian 'mega-urban' regions, jakarta, manila, and (more tentatively) ho chi minh city. the emergence of relatively small service sector occupational elites within mega-urban city-regions such as jakarta, and manila must be set against a vastly larger informal sector of hawkers, vendors, and peddlers, which mcgee described as the urban 'proto-proleteriat' (mcgee, ) . even in second-tier cities, such as bandung, economic restructuring incorporating both industrial development and tertiarization has promoted a deeply polarized social structure (pribadi and sofha, ) . the imposition of advanced, high order services within the central and inner-city areas of southeast asian mega-cities has produced a distinctive juxtaposition of socio-economic classes, typified in part by the persistence of shanty towns, squatter settlements and informal sector activities proximate to high-rise office towers, high-end shops and boutiques, and other accoutrements of the later th-century corporate complex (leaf, ) . as leaf observes, the explanation for this notionally incongruous pattern of traditional social morphology and modern capitalist development features "lies in the segmentation of urban land markets…which is now most commonly expressed in terms of formal and informal sectors…derived from early patterns of land use not governed by market principles" (leaf, : ) . in the case of jakarta, in which about three quarters of the population live in informal settlements (kampung), social class differentiation is expressed "not so much by zone or neighbourhood, such as what one would expect in the capitalist city, but at a more minute scale, between streetside and inner block locations within the same neighbourhood" (leaf, : ) underscoring the complex (and often deeply problematic) impact of economic restructuring on urban social structure within developing societies. the continuing economic crisis within southeast asian economies has no doubt impacted the poor disproportionately, but has also damaged the small service elite of professionals, financial and business services workers within the region's primate cities. in addition to the direct effects of this crisis on the employment and incomes of the service elite themselves, it seems likely that wider ramifications may include the diminution of the advanced services production capacity of these developing economies, as well as an erosion of the (already small) middle and upper-middle classes within their respective societies. ho chi minh city (formerly saigon) also exhibits a highly dualistic socio-economic structure, but differs from manila and jakarta in some important respects. more particularly, the introduction of the 'doi moi' (renovation) economic policy has forcefully inserted a before the 'crash' of there was a generally growing constituency favouring economic, social, cultural and even political association among the nations of the pacific basin, derived in part from a shared vision of mutual economic interests and visions of progress, as well as a preference among some observers to view the 'modernist project' in pacific asia through the western critical tradition (preston, ) . in the short term at least the fiscal and economic crisis of the past years in asia has diminished the enthusiasm of some in the americas and australasia to be associated with the wider concept of the 'asia-pacific'. there are also signs of a more 'inward' (i.e. intra-asian, as opposed to transpacific) sensibility on the part of (for example) japanese corporations and the chinese, japanese and malaysian governments, although the motivations for these attitudinal changes vary. former japanese vice-minister of finance eisuke sakakibara, for example, suggests that the membership of the us within apec precludes the latter from being a 'true regional organization,' while vice-minister ito observes that "[t]he task for asian countries is to ensure that regionalism in asian really complement global trading and financial systems, like other regional arrangements in north america and europe" (quoted in t. armstrong, 'asia is going it alone', the globe and mail, monday february : all). market presence within an established socialist political and social order, with polarizing outcomes for ho chi minh city's labour force and society. advanced services are emerging as defining elements of the new ho chi minh city as depicted in an approved mural extolling " years saigon and ho chi minh city: industrialization and modernization", the modernist imagery underscored by a dominant motif of point towers (drummond, ) . in this regard ho chi minh city is something of a 'frontier city', characterized by significant autonomy from hanoi, a situation somewhat analogous to that of guangzhou in southern china, which operates as a bastion of market enterprise in contrast to the more formal cultural and political style of beijing. at the same time, hanoi too is endeavouring to expand its engagement with the global economy in its development strategy, while maintaining a measure of local policy protection for long-established informal services, implying a bipartite planning approach to service industries (leaf, ) . the final two categories depicted in the typology of asia-pacific urban service centres comprise more narrowly specialized cities and settlements. category includes important port cities with (in most cases) substantial industrial sectors, and some service industries ancillary to port functions, but otherwise relatively underdeveloped advanced tertiary sectors. this set of port/industrial cities includes, to illustrate, pusan, kaohsiung, kitakyushu, oakland, and tacoma. a number of these cities are aggressively pursuing industrial diversification strategies in order to escape dependence on older (in some cases distinctly obsolescent) manufacturing activity; these include kitakyushu, pusan, and kaohsiung. each of these cities is actively promoting new service industries which are seen as more progressive development modes or vocations for the st century, and at least two, pusan and kitakyushu, are joint signatories to official co-operation agreements. the seventh category includes generally smaller cities and settlements specializing in travel and tourism. these include tropical centres, such as denpasar and kona, as well as the major skiing and winter sports centres of sapporo and whistler, the latter now the largest ski resort in north america. these centres may also be candidates for major international events: sapporo has hosted a winter olympics, while whistler is an integral part of vancouver's bid for the winter olympic games. as we have seen advanced services exhibit strongly polarized spatial patterns within the asia-pacific, reflecting the power of urban and agglomeration economies, and the locational centrality of higher-order services in metropolitan areas. at the same time, we can envisage the emergence of spatially extended territories of specialized services production and exchange at the broader regional level, configured as multi-centred urban corridors. these corridors (or clusters) comprise in most cases regions with a dominant first-or second-order global city and a chain of interdependent, and generally smaller, but nonetheless important urban centres. the conceptual bases for the emergence of these there is of course some ambiguity in this terminology, but in general corridors encompass essentially linear arrangements of cities, as exemplified in the pacific north west corridor (vancouver -seattle-portland), while clusters can describe patterns of functionally linked (but dispersed or non-linear in form) cities within extended regional settings (for example the california bay area, which includes san jose, the silicon valley, oakland and berkeley, as well as san francisco). specialized functional territories can be traced to gottmann's seminal idea of megalopolis (gottmann, ), whebell's theory of corridors as urban spatial systems (whebell, ) , and mcgee's notion of extended metropolitan regions (mcgee, ) . they perform strategic service functions (including finance, corporate control, administration, information and communications, cultural and gateway roles), are linked both to regional production systems and to global networks of services trade, and exhibit aspects of complementarity as well as competition. fig. shows the location of major urban service corridors or clusters within the asia-pacific sphere: five in east asia (central japan -honshu corridor, the lower yangtze corridor, the pearl river delta cluster, and the taiwanese and korean corridors); one in southeast asia (the southern malay peninsula corridor); one in australasia (the southeast australian corridor); and three on the pacific coast of north america (the southern california corridor, the california -bay area cluster, and the pacific north west corridor). reflecting the corporate power of the asia-pacific's firstorder global cities, the two most important extended urban services territories are the central japan -honshu corridor, which includes tokyo, yokohama, osaka, nagoya, and kyoto; and the southern california corridor, incorporating los angeles, anaheim, orange county, and san diego. these first-tier metropolitan services corridors contain truly global-scale concentrations of most of the specialized service industry suites listed in table , including banking and finance, corporate control, producer services, gateway functions, advanced-technology and creative services, education and culture. however, there are certainly global-or international-scale service industry concentrations situated within other principal service corridors and clusters, as exhibited in table . these include, to illustrate, the california bay area (global-scale advanced-technology and creative services, higher education, tourism), the korean corridor (banking and finance, corporate control, gateway roles), the pearl delta (banking and finance, corporate control, gateway roles), and the southern malay peninsula (banking and finance, gateway roles, advanced-technology services, education). within the more compact urban service clusters, the expansion of specialized services territories acknowledges the need to accommodate back-office functions and local services in smaller regional centres, and to situate new airports and port facilities, university sites, and research and development facilities in peripheral or exurban areas outside the dominant metropolis, with the pearl delta cluster as an example. culture, amenity and lifestyle may constitute supporting elements of intra-regional services development in some cases, notably in the transboundary pacific north west corridor. advanced services have been crucial to the post-staples development of the pacific north west; at the same time, the amenity provided by wilderness areas is widely seen as a positive inducement to the specialized services and advanced-technology industries which increasingly define the economic base of this region, and is also embedded in social values and lifestyles. within certain of the larger territories, notably the central japan -honshu corridor, the recent development of metropolitan service centres reflects the changing division of production labour at regional and even national levels, presenting possibilities of reciprocal specialization in services within hierarchical and otherwise competitive urban systems. at the same time, there are to be sure examples of the 'uneasy co-existence' of national primate and second-and third-order cities within extended clusters, derived from hegemonic inter-city relations; the examples of seoul and pusan, and tokyo and osaka, come to mind. the dynamics of regional competition and complementarity can further be illustrated by reference to the pacific north west corridor, which includes the three major ports of vancouver, seattle, and tacoma. there is to be sure considerable competition among the three ports (which is likely to increase as major shipping lines continue to rationalize their trans-pacific rotations), but we can also observe aspects of specialization and complementarity: seattle and tacoma are major container ports, while vancouver specializes in bulk commodity exports and cruise ship travel (the port of seattle has recently increased its efforts to attract cruise ship traffic, with at least a measure of success.). at a broader level, the reciprocal strengths of services specialization observed in seattle, vancouver and portland enable the north west corridor to compete in some trade sectors with the san francisco bay area cluster (for example in international gateway functions), about km to the south. in each case the emergence of these multi-nucleated, interdependent services production corridors may presage the reorganization of regional economic space to enable economies of scale, scope, and specialization, in response to the pressures (and opportunities) of globalization. within certain of these corridors, for example the yangtze delta cluster, and the southern malay peninsula corridor (incorporating singapore and the kuala lumpur -putrajaya -cyberjaya technology corridor) this developmental aspiration is a matter of quite explicit political strategy (see for example the discussion in corey, ( ) ). in the japanese case, the central government has attempted to promote complementary clusters or corridors of advanced-technology industries and services within three hierarchical levels, in order to maximize efficiency gains, and minimize damaging inter-regional competition (edgington, ) . there is a perceived need to transcend the everyday rivalries of regional competition, in order to promote powerful international-scale banking and finance, corporate control, education and culture services, production and trade platforms, along the lines of mature counterparts within the old 'atlantic core', such as the us northeastern 'megalopolis' corridor, the paris-ile de france region, and the london-oxford -cambridge triangle. a demonstration of the mutual benefits of inter-city complementarity and co-operation in this sphere may in turn facilitate broader efforts at inter-regional and international colloboration, as encouraged by douglass ( ), among others. at the moment, cities within the region tend to see themselves as entities within essentially competitive international urban systems, with an obligation to devote more policy attention and public resources to fostering competitive advantage, at the expense of planning efforts designed to enhance local welfare (thornley, ) . over the last decade or so urban policy approaches to service industry development have evolved significantly, reflecting in part a more informed appreciation of the centrality of advanced services to urban development. however, in other respects shifts in planning approach in this policy domain incorporate responses to the challenges and opportunities of globalization, and innovation in planning styles, as well as efforts to reconcile regulatory and distributive issues with important developmental aspirations. as in the fundamental processes of urban tertiarization described in preceding chapters, we observe a number of important contrasts in urban service industry policies between societies of the pacific and atlantic 'cores', notably a much stronger emphasis on growth and development aspirations among the former, as well as some commonalities. accordingly, this chapter will entail a discussion of defining shifts in urban policy approaches to service industries, leading to a presentation of six leading models of service industry models, together with illustrative reference cases, in the following chapter. we can identify several principal phases of local planning and policy responses to the growth of the urban service sector over the past quarter century. broadly, the initial period emphasized development control policies, to manage negative externalities associated with growth in speculative office development; the second phase included developmental programmes, acknowledging the increasing significance of service industries to local economies and labour markets; and the third period has seen more assertive policies which deploy advanced services as instruments of industrial restructuring, modernization, and globalization, as well as increasing policy innovation and experimentation. first, the rapid growth of offices within central city areas over the s and s gave rise to a suite of regulatory local planning policies toward the urban service sector (daniels, ) . planning concerns during this period included the implications of rapid office development for the over-specialization of the urban economy, for the displacement of non-office industries and housing, and for long-distance commuting within the regional commuter shed. indeed, the journey-to-work problem, shaped by the expansion of the cbd's office complex, and the simultaneous decentralization of the urban residential population and labour force, was broadly seen as a defining metropolitan planning issue in many city-regions (davis and hutton, ) . the planning response to high levels of central city office development over the s and s included both increasingly stringent development control policies for the core (including downzoning, the imposition of annualized development quotas or thresholds, and fiscal measures), as well as efforts to promote new office subcentres within suburban areas. local planning responses to office activity and other service industries in this critical policy phase at times took on a strongly ideological tone. in britain and in other parts of western europe, left-leaning councils actively discouraged service industries, which were seen as displacing traditional manufacturing industries. this essentially prejudicial local attitude toward service industries was in part conditioned by research which subordinated the tertiary sector to secondary manufacturing within the urban or regional economy, based on measures of export performance, productivity, and sales and employment multipliers. however, to some extent stringent local planning controls on (especially office-based) services were strongly influenced by political opposition to the speculative property market, which was seen to favour office development over industry and housing, reflecting higher returns on investment (roi) for office development relative to other land use categories. examples of this ideologically derived planning response to urban tertiarization included the greater london council and most inner city boroughs during the s and early s. urban authorities continued to experiment with development control options for service industries, but by the mid- s a more positive (or balanced) local policy approach was in evidence among a growing number of local authorities. this more favourable local policy posture toward office activity and other service industries was influenced both by the implications of industrial decline in many large-and medium-sized cities, impelled by the collapse of traditional fordist industry, as well as by new research which underscored the key roles played by specialized services in advanced (daniels, ) . more particularly, the specialized intermediate (or 'producer') services were identified as crucial to the operation of 'flexible' production systems, to high-wage urban labour formation, to industrial productivity, to the urban export base, and to local revenues. in this new situation, urban governments and planning authorities began to introduce policies for (at least selectively) encouraging important service industries, notably banking and finance, transportation, business services, higher education, and tourism (coffey, ) . examples of more positive local planning and policy instruments for the urban service sector are depicted in table , together with corresponding instances of development control and other regulatory measures, across a spectrum of local policy fields. table contrasts planning approaches toward service industries according to preferences for 'developmental' or 'growth management' policy objectives, although in practice many local authorities tended to implement a blended suite of promotional programmes and regulation . however, important examples of quite dramatic policy shifts can be referenced, notably within cities of the broadly defined asia-pacific region. in the well-known case of singapore, a short, sharp economic downturn in the mid- s led almost immediately to aggressive new policies favouring specialized, high-value, exportable services, in part reflecting concerns about the prospects for singapore's manufacturing industry and regional entrepôt roles. in hong kong, the colonial government assertively supported the expansion of office activity and other key intermediate services, exemplified by the territorial expansion of the cbd, by public investments in education, and by increased international marketing (taylor and kwok, ) . and in vancouver, a centre-left city council approved an economic development strategy which set out a series of policies and programmes to foster important service sectors and industries, together with co-operative measures to be undertaken among key institutions, labour cohorts, and business groups (city of vancouver, ) . at the same time, the city of vancouver continued to co-operate with the regional planning authority, the greater vancouver regional district, in managing externalities of rapid growth in services, for example by supporting office development in designated regional town centres (rtcs), exemplifying the tendency to 'blend' both regulatory and developmental programmes within local policy suites. the experimentation with development programmes for urban service industries over the s and s marked a significant departure from the strongly regulatory promotion of a better spatial balance between employment generation and housing growth a principal policy goal information services support for active marketing of tertiary services in domestic and international markets promote or market secondary centers in the suburbs (e.g. by publicizing cbd/ suburban rent differentials) government liaison/ 'partnerships' lobbying of central/middle tier governments to promote tertiary industry development; including for changes in government policy/regulatory environments (e.g. in the sphere of finance and banking, air bilaterals) support for government decentralization policies involving public and private sector tertiary employment source: after hutton ( ). experiences of the previous two decades. however, major changes in urban development conditions in the most recent period have led to a new phase of urban policy innovation, with policies for advanced services at the heart of much of this experimentation. these new policy conditions include the following processes, trends, and events: . continuing processes and pressures of globalization, stimulating local and regional policies promoting competitive advantage at the city-region level (as well as wellpublicized protests and demonstrations), but also encouraging interest in the possibilities of co-operative programmes between cities and local governments situated within 'extended metropolitan regions ' (mcgee et al., ) . . the severe (although spatially differentiated) impacts of major exogenous shocks on regional and national economies, including the aftermath of the / experience in new york, the bali night-club explosion of october , and the lingering effects of the fiscal and economic crisis in the asia-pacific. these impacts have included inter alia sharply diminished air travel and tourism in many regions, increasing unemployment, and problems of corporate illiquidity and bankruptcies. we can also acknowledge the recent impact of sars (severe acute respiratory syndrome) upon major asia-pacific service industries, notably airlines, hotels and retail trade. . economic and developmental implications of a series of unresolved security crises within asia and the middle east especially, including the apparently intractable palestinian question, the iraq crisis, and the problem of north korea's incipient nuclear capacity. these implications include a more problematic investment climate within affected nations and proximate regions. . the rapid rise (and even more dramatic contraction) of the so-called 'new economy', over the last years. the collapse of the dot.coms notwithstanding, however, information and telecommunications industries constitute essential features of all advanced economies, and are playing increasingly central developmental roles within the asia-pacific region (corey, ) . . the emergence of the 'urban cultural economy', underpinned by what allen scott describes as the convergence of culture and urban development, and comprising both cultural production and consumption as leading sectors within a growing number of cities and city-regions (scott, ) . cultural industries (including creative design industries, media and multimedia, and film, video and music production) represent increasingly important sectors of the urban economy, in cities such as los angeles, tokyo, kyoto, singapore, bangkok, and melbourne. . sharply divergent economic fortunes of the asia-pacific's major nation-states, including the remarkable growth of advanced industrial production and trade in china, the continuing japanese economic malaise, and slow growth in the american economy (the stagnation of american consumer markets has also seriously retarded exports from other asia-pacific nations.). . continuing processes of restructuring and transition among the advanced economies of east and southeast asia, including taiwan, south korea, and singapore, as well as in 'threshold' nics such as malaysia, thailand, and vietnam. to illustrate, an "important feature of asean economic development has been the growth of their services sector" (tongzon, : ) , as reflected in gdp and employment data. . new phases of development within the industrial structures and space-economies of asia-pacific city-regions, exemplified by processes of accelerated tertiarization, decentralization, and multinucleation among major chinese coastal city-regions (yeh and wu, ) , and by the emergence of 'new economy' clusters within inner city sites of cities such as tokyo, singapore, san francisco, and vancouver. . increasing awareness within the asia-pacific of ecological implications of accelerated development (and more particularly rapid industrialization), including resource depletion and overall environmental degradation, stimulating interest in principles of sustainable development. . exacerbation of urban social problems (increasing income disparities, social polarization, and community dislocation), both in rapidly growing states (notably china) and also in some lagging countries and regions within the asia-pacific. these social costs are discounted by some as inevitable outcomes of rapid economic growth, but there has also been evidence of interest in exploring possibilities for reducing social inequities, both in terms of new socio-political 'compromises' at national government levels (scott et al., ) , and also commitments to social planning as an integral feature of local government and administration. this illustrative listing of new development conditions inevitably masks quite highly differentiated experiences at the national, sub-national, and local levels, but may provide a backdrop to a new phase of experimentation in policy formulation and institutional innovation. clearly, these development conditions will influence new planning choices and directions across the full range of local and regional policy domains. in the aggregate, these conditions tend to 'stretch' local policy capacity and to place increasing pressure on urban planning systems, staff and resources. however, there may be promising opportunities for policy experimentation within the realm of the urban service sector, in light of the increasing centrality of service industries to trajectories of urban development, and the far-reaching implications of tertiarization for urban form and the built environment, the metropolitan space-economy, and the city's social structure (as well as derived demand for housing and transportation). in chapter we will explore some of the leading models of urban policy for service industry development within the broadly defined asia-pacific region. planning for new trajectories of services-led urban development as observed previously, urban planning and policy responses to tertiarization within the asia-pacific region include ambitious programmes which deploy service industries as instruments of development and transformation. a review of urban policy experiences over the last decade and a half discloses explicit associations between services (especially advanced, specialized and intermediate service industries) and plans for globalization, restructuring and modernization. while the mix of policy measures varies from place to place, these service industry programmes typically incorporate substantial public investments, inducements to attract private capital and the commitment of market players (foreign and domestic), adjustments to regulatory regimes, spatial planning elements, and sets of ancillary policies, notably in transportation and housing. the record of these ambitious (and even grandiose) policy initiatives includes some significant successes, in terms of the basic transformational aims (and business objectives of market actors), although the experience is also replete with examples of institutional conflicts and tensions. these include 'structural tensions' in some cases between local agencies mandated to vigorously promote growth and change, which tend to embrace narrowly economistic principles and objectives, on the one hand, and local planning departments which may prefer more holistic programmes, with broader, more inclusive public purposes. there may also be conflicts between central and local governments concerning policy preferences for service industries and economic development more generally. aside from these institutional tensions there are also growing concerns about social and environmental implications of rapid urban economic growth and transformational change. these include social costs such as community dislocation and social polarization, as well as environmental impacts which may include the destruction of heritage buildings within areas undergoing rapid change, encroachment of cities on adjacent agricultural and natural terrains, and the degradation of air and water quality within the regional biosphere. there are also examples of growing awareness of the financial and ecological costs of intense inter-city competition for investment, new service industries, and employment generation, which in some cases takes the form of a proliferation of facilities within extended metropolitan regions (as exemplified by airport development within the pearl river delta). these more problematic features of accelerated urban growth and transformation, coupled with the changing development conditions identified in the conclusion of chapter in britain this institutional tension at the local level is exemplified by the (sometimes conflictual) relationships between local 'regeneration' agencies mandated to promote new investment, industry, and job creation, and the local planning departments which perform a range of regulatory and management functions. similar tensions between local development agencies and municipal planning departments can be observed in west coast cities of north america, including vancouver. with respect to institutional tensions between local and central governments within the asia-pacific, we can cite the recurrent conflicts in development aspirations between the okinawa prefecture and tokyo ministries over the nature of okinawa's growth and change, exacerbated by structural problems of core-periphery asymmetry and dependency, as well as the increasingly problematic us armed forces bases on the principal island. , have stimulated new interest in planning innovation at the metropolitan and local government levels within the broadly defined asia-pacific region. while urban policies emphasizing transformational growth and change, underpinned by globalization and modernization aspirations, and by imperatives of competitive advantage, are still pervasive within the region, we can also discern significant interest in alternative (and perhaps more progressive) urban planning models. these include, for the purposes of illustration, experiments in sustainable urban development, community economic development (ced), and co-operative regional development. the purpose of this chapter then, is to depict the breadth of urban policy initiatives involving programmes for service industries, at the city-region and local levels, underscoring the dominance of transformational policies throughout much of the region, but disclosing as well interesting (and potentially significant) policy experimentation and innovation. while a comprehensive description of urban service industry approaches (and the programmatic details of these policies) is beyond the scope of this paper, it may at least be possible to structure a number of the leading models for comparative purposes. accordingly, table depicts six strategic policy models which deploy service industries as important instruments or modalities, together with some representative programme elements, underlying principles and values, and exemplary reference cases within the asia-pacific urban network or hierarchy. accordingly the framework of urban policy models depicted in table includes three ensembles associated with the dominant developmental paradigm of the latter period of the th century (associated with globalization aspirations, industrial restructuring, and modernization), and a set of three policy models which reflect current or emerging directions which seem to offer more progressive developmental possibilities. these latter three urban policy ensembles include policies for service industries which emphasize possibilities of co-operation with the broader regional setting, examples of initiatives which support the idea of the 'sustainable' city-region, and, finally, planning for the new urban cultural economy, acknowledging what allen scott describes as the strategic convergence between culture and urban development (scott, ) . what follows is a description and concise discussion of each of these defining urban policy models. over the past two decades both local and senior-level governments have deployed policies for certain service industries as key instruments of globalization (or internationalization) strategies within the asia-pacific region. objectives in this policy realm have included overcoming scale limitations of local markets and regional entrepôt roles (e.g. singapore and vancouver in the s); integrating regional and national economies within global markets, to attract foreign capital and promote modernization within the domestic economy (as in the case of certain chinese coastal cities since ); and pursuing strategic trade and co-operation partnerships with selected foreign cities (for example fukuoka since the early s). inter-city competition, concepts of competitive advantage, urban hierarchy; discounting of social costs (daniels, ) singapore (since mid- s); shanghai, osaka, fukuoka deregulation/privatization foreign direct investment urban mega-projects (after olds, ) service industries and 'postindustrial' trajectories pursuit of 'growth services' and propulsive intermediate service industries within context of industrial decline/obsolescence; acceptance of dislocation and displacement effects (hall, ) nagoya, hong kong, singapore land use policy change human capital investments targeted industry support programmes service industries and the 'new economy' assertive technocratic vision which privileges the future; idea of it as principal instrument of urban transformation and modernization; 're-imaging' of the city via policyinduced technological development (bunnell, ) kuala lumpur-putrajaya, singapore, vancouver support for r&d promotion of urban 'technopoles' spatial planning and land use policy service industries and the 'cooperative regional cluster' model acknowledgement of complementarity (as well as competition) among centres within extended metropolitan regions (emr's), after mcgee (douglass, ) hong kong/pearl river delta, sijori, san francisco-bay area region institutional co-ordination joint planning and marketing efforts spatial rationalization of new investment service industries and the 'sustainable city-region' model principles of social and environmental policy; idea of 'efficient and equitable' city-region; acknowledgement of sustainability as planning paradigm or framework (goldberg and hutton, ) sydney, vancouver, pearl river delta planning for suburban service industry subcentres services within 'compact' and 'complete' communities extensive designated 'green zones' service industries and the urban 'cultural economy' idea of strategic convergence between culture and urban development (scott, ) ; significance of creative industries and workforce (florida, ) los angeles, singapore, vancouver public support of the arts policy support for inner city clusters heritage planning promotion of the ' h' city we can identify a distinctive range of policy modalities that have been introduced to exploit the globalization potential of advanced, specialized service industries and institutions within the asia-pacific region. these have included: (a) building capacity in strategic urban transportation and communication, infrastructure and facilities, such as seaports, airports, and teleports; (b) promoting the export of specialized services (such as 'producer' and other intermediate services), in order to exploit local comparative advantage in services to replace diminished goods export capacity, to improve terms of trade, and to achieve greater scale economies within regional industries; (c) stimulating the globalization of cities in situ, as exemplified by the series of urbanmegaprojects (umps) within the region which have included important service industry elements, such as the pudong ump in shanghai (olds, ) , and the mm ump in yokohama, which tend to promote the inflation of local land markets, the increased presence of foreign firms and multinationals in the central areas, and the comprehensive re-imaging of the city; and (d) exploring the possibilities of mutual benefit through reciprocal, two-way trade in services (including educational and cultural services, as well as in business services) with designated cities as elements of international 'sister cities' or 'city partnerships', exemplified by fukuoka's 'global reach' programme (fukuoka municipal government, ) , and the city of vancouver's 'strategic cities' programme (city of vancouver, ). clearly there are important, substantive economic development and trade purposes associated with these globalization strategies, but there are also (explicit or implicit) reimaging aspirations in many cases. the classic example within the asia-pacific is the restoration of shanghai as a global centre of finance, corporate control, and business services, supported by assertive regional and central government policies and programmes, massive foreign investment, and the conscious engagement of elite international architects, planners, and developers in shanghai's accelerated transformation olds ( ) . other examples include yokohama's goal of escaping a constrained role as tokyo's 'shadow city' by means of the ambitious mm docklands scheme, as well as osaka's search for a larger international profile, to be furthered in part by the redevelopment of the cbd and the massive osaka -kansai international airport project. these urban globalization strategies have been centrepieces of local and regional development strategies for an increasing roster of asian-pacific cities over the past decade or so, with commensurate heavy commitments in local financial, policy, and human resources. in light of these major investments, a number of these globalization programmes have achieved a measure of success, in terms of accelerating growth, integrating cities within global markets, and other essentially economistic goals. however, there have also been significant social and environmental costs associated with these programmes, and high levels of local exposure to a variety of risks, as social and ecological values have (despite policy rhetoric to the contrary) been substantially discounted against the perceived benefits of accelerated globalization (see douglass ( ) for a treatment of the tokyo case study). the single-minded pursuit of transformational urban development through market integration, enhanced (or induced) comparative advantage in export service trade, and comprehensive local re-imaging has led to large-scale community displacement and dislocation (as in shanghai), high corporate and municipal financial exposure (yokohama's mm project, and tokyo's waterfront development), and inflation in local property markets (many instances throughout the region). these significant social and environmental costs tend to be associated with the more comprehensive, grandiose projects. correspondingly, more selective, smaller-scale or 'managed' internationalization programmes are likely to generate fewer such costs. again, examples of these more selective internationalization programmes would include the fukuoka experience, in which mutual benefit between urban communities represents an explicit aim; and the vancouver case, in which the city's internationalization programme in the s included both considerable stakeholder input, and measures to ameliorate social costs of accelerated urban globalization (hutton, ) . the development record of most cities within 'advanced' societies over the last three decades or so includes generally increasing shares of employment, gdp and exports accounted for by service industries. there have of course been debates about whether this trend toward the tertiarization of the urban labour force, output and trade represents a 'natural' process or progression, but what is incontestable is that some cities have endeavoured to accelerate the shift from basic manufacturing to services, especially specialized and intermediate service industries and employment. as noted briefly in preceding chapters, the asia-pacific region encompasses numerous case studies of this policy preference. central to the policy values underpinning urban programmes for restructuring which favour service industries and institutions is the (explicit or implicit) endorsement of the 'post-industrial thesis', first enunciated by the american sociologist daniel bell, which postulated a pronounced shift from goods to services production as a defining feature of advanced urban societies. (see table (a) and (b) for a more comprehensive set of urban tertiarization attributes). as kong chong ho has observed, cities have been obliged to respond to restructuring processes (ho, ) , including retraining programmes for displaced workers, and welfare programmes and transfer payments as well as policies to promote industrial restructuring as part of modernization strategies (hall, ) . in a number of cases, urban programmes of accelerated tertiarization have been undertaken within a context of urban-regional industrial decline or obsolescence. this has been observed within the japanese metropolitan system, where the 'hollowing out' of the national industrial economy has been deeply felt, in terms of factory closures (or relocation offshore) and protracted structural unemployment. for some of these cities, new service industries and associated labour cohorts, production and trade constitute a possible new urban development trajectory or 'vocation'. as noted earlier, too, urban development planning and programmes have been influenced by research which has established certain advanced services as urbanregional 'propulsive industries', based on associated productivity measures, inputoutput relations and sales and employment multipliers, export propensity, and skilled labour formation. here, the large-sample survey of export services undertaken by beyers et al. in the mid- s for the seattle-central puget sound economic development district (cpsedd) has been especially influential in providing an empirical justification for services-oriented metropolitan development strategies (beyers et al., ) , complemented by theoretical work undertaken by peter daniels, jean gottmann, and others. important case studies of accelerated tertiarization within the asia-pacific include singapore, hong kong, and nagoya. in the case of the former, a short but sharp recession in the mid- s stimulated a comprehensive policy research exercise in singapore, culminating in an important development policy shift favouring intermediate services with high export propensity (or potential). underpinning this defining policy shift was the work of a special subcommittee exploring the merits of manufacturing-versus services-led urban development and growth. the subcommittee concluded that advanced, specialized services enterprises "contribute about twice as much value-added as manufacturing firms" (clad, ) , and constituted a more promising growth sector than most forms of goods production. accordingly the government of singapore embarked upon a comprehensive programme to accelerate growth in specialized services in , including incentives for foreign investors, new expenditures in education and training, sweeping fiscal changes (including major tax cuts, and reductions in payroll taxes), service industry support programmes, and marketing and information strategies. in hong kong over the same period the colonial government was also engaged in policy support for an increasingly post-industrial economy and workforce. as observed by bruce taylor and reginald win-yang kwok, this accelerated tertiarization strategy comprised important policies for urban structure and land use, including major land reclamation in wanchai and causeway bay to accommodate the expansion of hong kong's cbd, the ongoing industrial new town programme in the new territories to enable relocations from the central district and kowloon, and new investments in rapid transit (taylor and kwok, ) . as a measure of the effectiveness of this programme (coupled with the influence of market-driven change), services now account for over fourfifths of hong kong's labour force, and there is more employment in intermediate (or business) services than in consumer services (asian development bank, ) . in both the hong kong and singapore examples it can be argued that these policy shifts essentially reinforced (or accelerated) post-industrial urban vocations already in progress. however, the experience of certain japanese cities offers a quite different set of policy conditions and experiences. david edgington has written extensively about the role of industrial restructuring policies for the important nagoya -chukyo region, a key part of japan's industrial heartland. he depicts schematically a progression of new industrial vocations for chukyo over the second half of the th century, which includes (first) a mix of heavy industry (aircraft production and munitions) up to the s; secondly, a shift to heavy industries (steel and petrochemicals) and consumer products over the s; followed by strong growth in auto production (toyota), heavy engineering, and light industries during the s and s. however, the last decade in the nagoya -chukyo region has seen new local (prefectural and municipal) policies and planning in support of a 'new vocation' of knowledge-intensive industries, including aerospace, advanced electronics, new ceramic materials, information technology, biotechnology, and fashion design and production (edgington, : ) . this new vocation builds upon the nagoya -chukyo region's embedded excellence in advanced industrial production, but with greatly enhanced services, design, and technology inputs to production. here, the role of local government (as distinct from the well-known national government industrial support programmes) has emphasized "strengthening regional culture, design and general amenity upgrading for chukyo" as an "important part of regional restructuring" (edgington, : ) . the nagoya -chukyo experience represents an example of complementarity between central and local governments in promoting industrial restructuring at the regional level. the emergence of a 'new economy' characterized by propulsive roles for advanced information and communications technologies (ict), although to be sure a contested concept, has stimulated considerable interest among governments and policy communities within the asia-pacific. for a number of jurisdictions, policies for supporting ict are seen as means of rejuvenating urban and regional industrial production sectors (notably in japan), while in others investments in ict, implemented by spatial planning, land use, and human capital planning programmes, provide a means of 'leapfrogging' stages of economic development (malaysia). technology-driven development has also been central to new urban development experiments, as in the case of the tsukuba science city in japan. as a planning preference, support for accelerated ict development and other new economy activity can be seen as the endorsement of an assertive technocratic vision of urban and regional development, as observed by manuel castells in his discussion of 'the informational city' (castells, ; scott, ) . ict is deployed as a key instrument of urban transformation and modernization, with both 'substantive' effects (higher productivity and value-added production; business start-ups and labour formation) and 'symbolic' outcomes (re-imaging of local/regional societies and economies), although there are to be sure concomitant costs and dislocations (bunnell, ) . within the asia-pacific, we observe a number of instructive examples of ict-driven development strategies at the urban and regional levels. there are of course the globalscale advanced-technology regional complexes of silicon valley and orange county in california, seen as essentially 'spontaneous' (i.e. market-driven) enterprises, although the role of state-supported universities and other public agencies should be acknowledged. then there are the large r&d formations (applied research, prototype development) within japan, largely funded by major japanese multinationals and industrial conglomerates, but also influenced significantly by central government ministries and agencies. these massive american and japanese r&d complexes have of course been established for many years, and represent in some ways an earlier model of technologydriven spatial development linked to large industrial corporations. a number of other, newer examples of new economy exhibit in some respects different attributes, including larger roles for government and public agencies, more emphasis on integrated service industry engagement (including creative and design services, as well as financial, business, and communications services), and contrasts in scale. the range of examples in this more recent cohort of technology-driven enterprises varies from the extensive putrajaya -cyberjaya project in malaysia, described by kenneth corey as a defining project of malaysia's national economic development programme (corey, ) , to a series of inner city new economy experiments within a large and growing number of cities, including singapore and vancouver. these recent inner city new economy projects are clearly differentiated from the 'first generation' urban and regional technopoles in a number of ways, not only in the matter of scale, location, and provenance, but also in the mix of industries and activities. key to these new inner city formations is the concept of the metropolitan core as a special, in some ways unique, 'innovative milieu', providing advantages of socio-cultural, as well as economic, agglomeration, to constituent firms. there is also, as noted, a stronger service industry element, as in both the singapore and vancouver examples the explicit strategy involves fostering developmental synergies between technology (especially ict), culture (in the form of creative and design service industries), and 'place', as expressed in the innovative milieu of the inner city. these inner city new economy sites are characterized by intense interaction (formal and informal), deployment of both 'placed-based' and 'cyber-based' production networks, and a distinctive demography, emphasizing mostly younger creative and technological workers and entrepreneurs. . . . service industries and the 'co-operative regional cluster' model as is well known, the development experience of the asia-pacific region over the past four decades has been characterized in large part by prevailing attitudes of competition for shares of investment, trade, and new employment formation, between (and among) nationstates, regions, and even cities. this animating sense of competition between jurisdictions has at times been exacerbated by contrasts in stages of development, by ideological factors, and more forcefully by the pressures of accelerating globalization. development policy postures have therefore in many cases been influenced by a perception of regional development opportunities as a 'zero-sum' process of clear 'winners' and 'losers', leading to an emphasis on nurturing localized positions of competitive advantage (douglass, ) . assumptions of development as an essentially competitive process are of course still powerful influences on policy formation within the region, but there are also significant (and likely expanding) movements toward inter-jurisdictional co-operation, shaped by progressive ideas of reciprocal trade benefits, knowledge-sharing, and developmental complementarity. this is seen at the broadest spatial scale in the establishment of the apec grouping, an association which endeavours to promote liberalized trade and cooperative development within the pacific sphere (as well as providing a counterweight to other continental-scale bodies, notably the eu and the nafta states). at the regional level asean provides a forum for dialogue and trade co-operation among the states of southeast asia. then there is a steady proliferation of less formal regional co-operative associations, including a number of such entities in northeast asia (kim, ) , and joint international development projects, exemplified by the sijori (singapore-johore-riau) growth triangle in southeast asia, and the tumen river area development project in northeast asia (marton et al., ) . many of these developmental arrangements are replete with significant institutional asymmetries and tensions, but they may suggest the possibility of greater tendencies toward regional co-operation, perhaps working over the longer term to approach the levels of engagement and co-operative commitment of the 'associative regions ' (mcgee et al., ) of the eu. more specifically, it may be possible to envisage regional co-operation arrangements based in part on the functional complementarities of regionalized service industry clusters and corridors, described in chapter . as will be recalled, it is possible to identify at least conceptually ten major service clusters or corridors within the asia-pacific, each containing multiple cities and important ensembles of specialized service industries, institutions, and facilities. as in other co-operative ventures at the regional scale, there is an initial need for governments, business interest, and other stakeholders to recognize and acknowledge possibilities of complementarity and mutual benefit associated with these complexes of specialized service industries. in the absence of joint governance, common taxation regimes, and revenue sharing (in addition to issues of (for example) labour market standards and environmental norms) these co-operative regional arrangements may be problematic, but the difficulties may not be insuperable. indeed, the nature of service industry specialization may in many cases lead itself to a broader recognition of co-operative possibilities, even in cases where inter-jurisdictional competition has been the prevailing spirit. co-ordination of investments, operations, and marketing for strategic transportation and communication facilities, for example, can enhance the comprehensiveness of 'gateway' functions for an extended regional corridor or cluster. co-operative planning and programmes for regional tourism initiatives, involving a diverse range of assets, amenities, and hosting infrastructure (e.g. hotels and convention centres) which offer greater potential attraction to visitors than the individual, localized sites within the region, can yield mutual benefits. potentially these principles of co-operation and co-ordination could apply in other important service sectors and industries, for example higher education and specialized health case, acknowledging the advantages of 'packaging' services and expertise offered by diverse firms and institutions within extended regional territories. through greater levels of co-ordination and planning of specialized service functions, regions can achieve stronger competitive positions within international and global markets. within the asia-pacific, the hong kong -pearl river delta offers a particularly instructive case study. following the economic reforms introduced by deng xiao-ping in , the pearl delta experienced extraordinary levels of growth in investment, business start-ups, employment formation and physical development. much of this growth was in the goods production sector, especially light manufacturing, but (as observed in chapter ) the prd also experienced rapid expansion in services. however, there was a chaotic pattern to much of this development, as evidenced in the growth of the shenzen special economic zone (sez), and in the proliferation of new airports within the delta. this period of rapid growth was also characterized by an almost 'free for all' competitiveness among the urban centres of the region. although the prd has experienced high levels of growth over the past two decades within an essentially competitive context, there is significant evidence of co-operation and co-ordination in recent years, especially since the establishment of the hong kong special administrative region (sar) following the reversion of the former crown colony to china in . these efforts to pursue co-operation in economic development have been documented in a recent book edited by anthony gar-on yeh et al. ( ) , titled building a competitive pearl river delta region: co-operation, co-ordination, and planning. to some extent, of course, this desire to achieve co-ordination is related to the need to avoid wasteful, inefficient duplication of functions, to preserve resources, and to rationalize spatial planning in a congested, high growth region. there is also a need to 'manage' competition between the two major centres of the region, hong kong and guangzhou (kwok and ames, ; cheung, ) . however, an important principle underpinning the increasing levels of co-operation within this administratively fragmented and complex region is the exigency of responding to pressures (and opportunities) of globalization. in this respect, the pearl river delta contains both a dense pattern of manufacturing and industrial production, as well as concentrations of specialized service industries, institutions, and functions, including banking and finance, seaports, airports, higher education, cultural and creative services, and public administration. these specialized services represent the best prospects for future growth and development in the region, and greater co-operation and co-ordination of these key services can significantly strengthen the prd's competitive position within east asia and global markets. there is considerable potential for co-operation in the planning and development of other major regional service clusters and corridors within the asia-pacific. the basic idea is to explore means of managing competition between service industries and installations within regional settings, while capitalizing on functional complementarities to achieve stronger international competitiveness. much of the regional co-operation within the region over the past years has been undertaken for areas specializing in manufacturing and industry, as in the sijori and tumen river area projects cited earlier. however, given the momentum of tertiarization within the asia-pacific, and the strategic global functions performed by certain service industries, institutions, and firms, co-operative management and co-ordination of regional service clusters present especially promising possibilities for future urban and regional development within the asia-pacific sphere. there is a need to strengthen regional governance and administration as a pre-condition, however, as the lack of effective regional institutions represents a major constraint. as an example, the association of bay area governments (abag) in the san francisco bay region provides a forum for inter-jurisdictional dialogue and a certain amount of coordination, but lacks the capacity to promote effective regional development co-operation. in addition to the transformational roles described earlier, service industries are increasingly deployed as key elements of spatial and land use planning within the asia-pacific, including a new generation of regional plans influenced by principles of sustainable development. although the specific forms of these new city-region plans of course vary from place to place, we can discern features of three important traditions of spatial (or physical) planning, as follows: (a) elements of spatial planning derived from the classic 'containment' model of planning for metropolitan city-regions, incorporating stringent development control on commercial development in the central city, the establishment of green belts or zones, and the designation and development of new (or expanding) towns on the regional periphery, as seen in the post-war planning of london and the south east region of england (hall et al., ) , and updated in the sequence of 'structure plans' for english counties in the s; (b) attributes of 'new urbanism' planning models (and related concepts) introduced in the s, which included the ideas of 'compact' (as opposed to dispersed) and 'complete' (in contrast to dormitory) communities within city-regions, an emphasis on transit-oriented development (tod) (and the increased management of automobile traffic), and a preference for 'traditional' (or 'neo-traditional') housing styles and vernaculars; and (c) principles of 'sustainability' (or 'sustainable development'), which have increasingly influenced the planning of city-regions (as well as 'natural' or 'resource regions') since the rio 'earth summit' of , and which encompass ideas of ecological preservation, biodiversity, the integrity of ecological systems, and the need to manage (and eventually reduce) the human 'ecological footprint'; i.e. the impress of human activity on the world's natural resources and biosphere. in the urban context, sustainability principles can also be applied to the city-region's economy, culture, and social 'capital'. the extent to which principles derived from these major models of urban and regional planning is dependent not only on considerations of urban scale, environmental setting, industrial structure, and growth rates, but also on the structure of urban governance, the nature of political control, characteristics of the local planning system and policy agencies, the quality of leadership, and other institutional factors. at the broadest level, however, there is a kind of structural tension associated with contemporary spatial planning for metropolitan regions, between the need for flexibility to accommodate changing locational demands of business and industry (including the so-called 'new economy' activities) and new residential preferences, on the one hand, and the imperative of deploying policies to impose a measure of order on the growth of human settlements, in accordance with ecological and social values. service industries have been assigned roles within each of the three principal spatial planning ensembles cited earlier, although these have been demonstrably subject to change. within the 'first-generation' containment models growth management, development control, and the accommodation of population growth by means of supporting designated regional centres were dominant aims, and services (including offices) were addressed primarily by a suite of regulatory policies in the early post-war programmes, as described in chapter (goddard, ) . however, a 'second generation' of regional plans in the s, derived from the containment model in britain, canada, and numerous other states, included the idea of rtcs (or commercial subcentres), within which office development and firms were assigned important roles. these new suburban or regional subcentres were intended to attract new office development, not only to manage development pressure on the cbd, but also to provide more employment opportunities in areas of rapid population and labour force growth, thereby also reducing commuting pressures. within the rubric of new urbanism, offices and other service industries were also seen as important spatial planning elements. to illustrate, concentrations of relatively high-density service development can enhance prospects for the formation of 'compact' (as opposed to dispersed and low-density) communities, while the inclusion of service functions and employment were central to the implementation of 'complete community' strategies. finally, although sustainable development has emphasized the primacy of ecological values and environmental planning, service industries have a number of important implications for sustainability planning. the status of services as the most rapidly growing elements of many urban economies has ramifications for resource consumption (including land), while the mismatch between service employment concentrations and residential development exacerbates the metropolitan commuting and traffic congestion problems, impacting regional air quality. at the same time, the fortunes of the service sector and its constituent industries also have a clear connection to the socio-economic sustainability of the metropolis, especially in light of contractions in fordist manufacturing. . . . . experiences within the asia-pacific. the highly differentiated stages of development and local institutional arrangements among asia-pacific city-regions offer a rich array of experiences in policies for service industries within spatial plans. these include a substantial sampling of metropolitan cities which have deployed containment strategies or 'structure planning' concepts, incorporating the designation of secondary office-commercial centres or subcentres. this has been especially the case in jurisdictions strongly influenced by british planning models, notably australia, canada, singapore, and hong kong, but resonances of the containment model and its defining features (green belts, new residential communities, and designated service industry subcentres) are also discernible in japanese city-regions. we can also identify aspects of the new urbanism and sustainability models in a growing number of city-region plans, although in most asian cities the experience is in incipient stages. a (necessarily concise) selection of reference cases follows. as observed earlier, the location and development of service industries within guangzhou and the pearl river delta (as well as other fast-growing chinese cityregions) has become a major spatial planning issue over the past decade, and underscores the tensions between accommodating growth and the pursuit of sustainable development. within the guangzhou city-region, the combination of liberalized development policies, a greatly expanded role for the market, and high levels of growth have reshaped urban structure and land use over the last years, as disclosed in a recent empirical study by fulong wu and anthony gar-on yeh. during this period, there has been substantial redevelopment within guangzhou's central city, but its overall spatial reconfiguration "is changing from a compact city to a dispersed metropolis as a result of reforms which introduced land values and markets to its urban areas" (wu and yeh, : ) . a measure of this dispersal and sprawl consists of industrial estates, but new service industries and commercial development, driven in large part by foreign investors, also play a role in this process. as wu and yeh conclude, "[the] conflict between urban spatial restructuring and development control is inevitable" (wu and yeh, : ) in high-growth cities characterized by the decline of central planning and inadequate local planning powers. michael leaf goes even further, asserting that in these dynamic chinese cities, "the practice of urban planning may have passed from irrelevance under the command economy of the past to gross ineffectiveness in the socialist market economy of today" (leaf, : ) . moreover, local planning systems in at least some chinese cities are developing more sophisticated planning styles, and an increasing number of planning professionals are engaged in exploring sustainability principles, so it may be that the next generation of city-region plans will incorporate stronger elements of sustainable development. other reference cases within the asia-pacific provide quite different experiences of spatial planning and contrasting perceptions of the role of services in regional sustainable development. the evolution of spatial planning in metropolitan vancouver represents a sequence of new roles for service industries, from 'containment' to sustainable development. in vancouver's first regional plan, the livable region region - (approved , the classic elements of the post-war containment spatial plan were all present, including green zones (incorporating special protection for agricultural land, an emphasis on public transit, and the designation of four regional (suburban) town centres, each of which was to attract one million square feet of office space over the term of the plan. at the same time, the regional plan proposed strong development control policies for the cbd, both to ameliorate commuting and to enhance office development prospects for the rtcs (hutton and davis, ) . two decades later, a new livable region strategic plan (lrsp) ( ) affirmed the multinucleation strategy of the earlier plan, and indeed added several new rtcs, but also introduced policies for 'compact' and 'complete' community formation, influenced by the new urbanism spirit. service industries were allocated important roles in the lrsp, as the concentration of new offices in the (now eight) rtcs would support the principle of compact settlement forms, while a more diversified range of both intermediate and final demand services (including commercial, retail, and educational services) would promote the formation of complete communities within the city-region, integrating important service functions and local employment opportunities with residential development. more recently, a new public process has been initiated by the greater vancouver regional district, the regional planning agency for metropolitan vancouver, with a view to more vigorously asserting sustainability values and principles in the lrsp. this initiative includes the possibility of strengthening the (already-substantial) ecological conservation measures of the regional plan, but there is also a new emphasis on the importance of economic sustainability as a critical planning priority. in this new planning consultation process, key informants, stakeholders, and the general public are invited to propose new ideas for enhancing the economic sustainability of the region, including the spatial planning implications of new service industry development. these include the cbd (now seen as a unique and valuable regional assets rather than principally a generator of negative externalities, as interpreted in the metropolitan plan), the eight designated rtcs, the port of vancouver, vancouver international airport, the region's universities and colleges, and a number of 'new economy' sites, both in the suburbs and in the metropolitan core. spatial planning measures for service industries that promote multinucleation within metropolitan strategies can be seen as supporting economic sustainability (nurturing of high growth service industries, building capacity for industrial transition, enhancing regional economic resilience) as well as ecological sustainability (conservation of scarce urban land resources, mitigation of commuting-related air pollution). agglomeration of advanced service industries promotes the 'cluster-driven' process of advanced urban development, as seen in the vancouver example described earlier. other important examples within the asia-pacific include the global-scale concentration of advanced-technology service industries clustered in redmond, washington, within the metropolitan seattle-king county city-region, and the recent development of sydney's north shore high-tech corridor. this corridor has seen a functional and spatial evolution over the past four decades, initiated in the s by a secondary cbd in north sydney, at the north end of the sydney harbour bridge, followed by the establishment of a major regional shopping centre in the s, and the development of macquarie university on a nearby site (o'connor et al., ) . with these activities serving as a base, the last two decades have seen the dramatic growth of new technology-based industries and advanced services: the north shore corridor is anchored by microsoft corporation at one end, and cable and wireless optics at the other, with five commercial clusters situated between these two major poles (o'connor et al., ) . by the mid- s, employment within the north shore corridor exceeded , included jobs situated within member companies of the australian information industry association (o'connor et al., ) . sheehan quotes a property consultant as describing the north shore corridor as "technology land, but it's not physical production, it's brain power and computer power, biased toward sales, service and management rather than research, development and production" (sheehan ( : ) , as quoted in o' connor et al. ( : - ) ). clearly, on this evidence, market players (investors, entrepreneurs, and professionals) have been central to the development of sydney's north shore corridor, but government and public agencies have played leading roles in terms of regional spatial planning, municipal land use policy, and in tertiary education investment. the sydney north shore corridor experience also vividly depicts the functional evolution of service industry clusters over time, in this case from a secondary office and shopping centre to an incipient high-technology site, and finally to a large-scale 'new economy' site of national significance, including advanced-technology industries and specialized service functions. urban centres within the asia-pacific region, as elsewhere, have played important roles as repositories of signifying local, regional, and national cultures, as exemplified by cities such as beijing, kyoto, and hanoi, and many others. these important cultural roles are manifested in (for example) language and dialect, in museums, galleries and archives, in institutions of higher learning, in the built environment, and in social organizations and agencies. these cultural activities have economic as well as social value, as expressed in direct employment generation and incomes, tourism receipts, and the capital value of infrastructure, including heritage buildings. these traditional cultural roles continue to be important (albeit recurrently renegotiated by political acts and social experiences, and subject to new cognitive filters), but are now significantly augmented by fresh processes of reproduction, innovation, and economic development, both in the market and public domains. over the last decade or so, we have witnessed dramatic growth in a range of creative, design-based and 'new cultural' industries. as allen scott has observed in a well-known treatment of 'the cultural economy of cities', "[a]s we enter the st century, a very marked convergence between the spheres of cultural and economic development seems to be occurring" (scott, : ) . within cities, the expansion of this new cultural sector includes film, video and music production, graphic artists, industrial design, fashion design, and architecture, as well as 'hybridized' firms which combine creative and technological outputs toward products (goods and services) imbued with high design content, including multimedia and 'new media' activities, internet graphics and imaging, and software design. again to reference scott, "an ever-widening range of economic activity is concerned with producing and marketing goods and services that are infused in one way or another with broadly aesthetic or semiotic attributes" (scott, : ) . creativity is an essential element of the city's role as centre of innovation, in cultural, industrial, and intellectual realms (hall, ) . within the broadly defined asia-pacific region we can readily identify some leading exemplars of this 'new urban cultural economy', such as los angeles (film production and post-production, music, and media), tokyo (media and communications, architecture, design-based industries), seattle (software design, music production), hong kong (music, creative and design-based industries, media and communications), singapore (advertising and corporate branding, multimedia), melbourne (creative and design-based industries), and vancouver (graphic design and multimedia). the rapid expansion of these important new industries can be seen as the most recent development phase in the continuing evolution of the urban service economy, and the enduring competitive advantage of cities for specialized cultural production, as well as the reassertion of production activity in the inner city districts of some urban areas. moreover, these new forms of specialized cultural services production are characterized by a distinctive interface with consumer markets, as many of these industries supply what scott terms 'cultural products' (scott, : ) which influence public tastes and preferences, and are concerned with differentiating consumer market segments. the 'new cultural economy' represents a leading-edge urban policy area. within the mature urban societies of the atlantic core, there is a significant record of policy innovation. for example, within the eu, there are numerous programmes for both national and local governments to support cultural industries, including the annual designation of 'european cultural cities'. at the national level, the british government has produced detailed inventories of cultural industries, including employment, sales, and exports, as well as policy guidance for local authorities. in north america richard florida has written about the crucial importance of the 'creative class' of service workers for advanced urban economies, and has emphasized the need for progressive policies (liberal immigration policies, generous public support of the arts) to attract and nurture this creative workforce (florida, ) . within the asia-pacific, the new cultural economy should emerge as an increasingly important component of service industry strategies and more comprehensive economic development programmes. in singapore, the tourism board is active in promoting activities which intersect the new economy (technology-intensive industries) and the new cultural economy, including internet design firms, advanced design, and other creative services, concentrated within designated sites in chinatown, just west of singapore's cbd. as another example, far east properties has entered into an agreement with the government of canada, nortel networks, and the eu to sponsor a new business centre in another area of traditional chinese shop houses, just east of cross street, demonstrating again the possibilities of co-operative development in the advanced service economy. the refurbishing and subsequent 'recolonization' of these important heritage districts suggests that culture and social memory can be reconciled at one level with economic innovation, although there are of course sublimated tensions in these processes of transition and appropriation (see yeoh and kong, ( ) for insightful treatments of these issues). west coast cities in north america are also active in promoting the new cultural economy sector. los angeles and san francisco have agencies which promote new activity including these new cultural economy industries. in vancouver, the municipal government has undertaken comprehensive land use and rezoning to facilitate the transformation of a large ( ha) inner city site from traditional industry, warehousing and industry to new industries which interface with the technology and cultural sectors. this project includes a new campus (great northern way campus) comprising units of four vancouver-area universities and colleges, which has been established both to stimulate industrial innovation in the larger site, and also to encourage synergies between design-based and technology-based industries. there is also support for cultural and creative service industries among certain chinese cities. as observed earlier beijing's current plan strongly endorses the city's traditional cultural role, but there is also significant innovation in contemporary art and creative industries among beijing's universities and art schools (fackler, ) . in shenzen, a new three-year study of the city's dynamic cultural industries will include empirical research on clustering, linkage patterns (both place-and web-based), and the discourse of cultural landscapes, both to enlarge scholarly appreciation of these industries, and to inform policy (li, , personal communication) . on the other hand, the city of shanghai is demolishing the warehouses along suzhou creek which have provided a distinctive milieu for artists, artisans, and other creative workers. this eradication of shanghai's artist-loft district has been criticized as inimical to the fostering of cultural industries which complement the commercial functions of world cities, and to the emergence of an important 'spontaneous' (as distinct from induced) creative services cluster. lu yongyi, a professor urban planning at tongji university, has asserted that "[i]t will be too late when they realize these ruined communities were things of value that can never be rebuilt" (fackler, ) . by way of contrast, the residential high-rise towers which will replace the suzhou creek warehouse district, while meeting to be sure social needs, are replicated throughout the city, and could have been accommodated elsewhere in the comprehensive redevelopment of shanghai. finally, an increasing number of cities are exploring the ' h city concept' as a means of supporting the lifestyles of workers engaged in creative and 'hybridized' designtechnology enterprises. research has indicated that many of these professionals, artists, and entrepreneurs have irregular working hours, and are attracted by the h urban amenities of restaurants, night clubs, and all-night 'raves', as well as alternative recreations, such as skateboarding. these all-night activities do create tensions in residential areas within the inner city. here, there are possibilities for effectively integrating social planning, cultural programmes, and advanced service industry policies to nurture the development of these important new cultural and hybridized industries which constitute ascendant features of the st century inner city among advanced urban societies. conclusion: an agenda for scholarly investigation the purpose of this exploratory paper has been to establish tertiarization as an increasingly important process of urban development within the asia-pacific. the growth of advanced service industries will be crucial to the development of asia-pacific city-regions (and indeed to national economic progress) over the first decades of the new century. more particularly, advanced, specialized service industries will be central to employment and human capital formation, to the expansion of the urban middle class, to the more efficient operation of advanced industrial production systems and trade networks, and both to urban competitive advantage and the socio-economic sustainability of asia-pacific cities. reinforcing this latter point, many of the region's large industrial metropoles will begin to 'shed' manufacturing employment (as experienced in the wrenching deindustrialization of mature atlantic city regions, and in the 'hollowing out' of japanese manufacturing capacity), and will need services growth to partially offset these contractions. at the same time, growth in advanced service industries and employment will require greater public policy commitments, not only in the areas of infrastructure and supporting systems, and in land use policies, but also in education and training. here, we can return to an earlier comparative theme addressed in this paper, by acknowledging that effective policies for services (incorporating developmental as well as regulatory elements) have been seen as lacking in the old atlantic core coffey, ) , despite a relatively early experience of growth in advanced services within the region as a whole. the cities of the asia-pacific (and their respective central and regional governments) will need to develop more innovative policy approaches toward service industries over the next decade and beyond, reflecting the increasing significance of advanced services for economic transition and modernization. moreover, it must be acknowledged that policy selection in this sphere entails value choices (and conflicts). the facilitation of advanced services growth can, as we have seen in a number of asia-pacific cities, entail the dislocation of traditional industries, informal services, and residential populations. a balance must be struck between the imperatives of economic modernization and the claims of social justice, as well as respect for diversity and pluralism. a progressive urban planning posture should support the preservation of informal services and historic city districts, both of which sustain the authenticity of local identity, while at the same time promoting the intermediate, technology-based, creative and other specialized services essential to development. the idea of sustainable development, which has been articulated in some urban strategic plans within the region (at least at a rhetorical level), may present a progressive planning framework for integrating social, economic, and ecological values. recent research has disclosed that there may in fact be significant policy complements intersecting urban sustainability and competitive advantage, including policies for compact urban structure and land use, efficient transportation and transit, and education investments (goldberg and hutton, ) , which may inter alia support advanced service industry development, as well as enhancing social welfare and ecological sustainability. to some extent the expansion of service industries within the asia-pacific has assumed basic features of the earlier urban tertiarization experience within the mature regions of the atlantic core, but in other respects has been quite distinctive. these contrasts can be attributed in part to different models of intermediate services production and exchange, to the special roles of government policy in promoting accelerated services growth, and to the marked disparities in overall development at national and regional scales within the asia-pacific. these contrasts were identified and incorporated in our provisional typology of urban service specialization. the differentiated growth rates and levels of specialization in advanced services decisively influences urban hierarchy within the region, as well as patterns of services trade and exchange, and global city-region status (rimmer, ) . indeed, one of the salient issues for the future will be the extent to which full globalization processes may override established regional service markets, for example in finance, property and real estate, among others. the specialized service centres and corridors described earlier may emerge as platforms for the globalization of services produced within the asia-pacific, as well as engines of development within the region. the narrative suggests a mandate for scholarly inquiry into the growth and development of service industries within the broadly defined pacific realm, derived from attributes of the tertiarization experience which include ( ) relatively high growth rates of service industries and employment in an expanding number of pacific societies over the past decade or so; ( ) the larger developmental implications of rapid tertiarization, whether viewed as an important extension of industrialization, or as essentially a new phase of socio-economic development; ( ) the more specific consequences of rapid services growth for urban (and more categorically metropolitan) areas, and especially the role of tertiarization in processes of urban transition and transformation; ( ) the distinctive interface between public policy and market forces in the acceleration of service industry growth in many cities and regions of the asia-pacific; and ( ) the more problematic outcomes and impacts of service industry development within the pacific new core, including displacement and polarization impacts, exacerbation of globalization pressures on existing industries and local communities, and the special problems presented by the larger economic crises within east and southeast asia in particular, a phenomenon which has had serious consequences for the service industries of the region. no doubt other themes could be elucidated (beyers, ) , but even this necessarily selective inventory of strategic considerations presents a rich, stimulating and potentially consequential agenda for scholarly research. in addition to these empirical problems and policy issues, there are important theoretical questions to be addressed, associated with the role of tertiarization processes in the structure, growth and transformation of city-regions within the asia-pacific. there is a need to reconsider urban models embedded within the industrialization paradigm, in order to accommodate the increasing influence of service industries in the development of urban regions within the pacific realm. these theoretical exercises will naturally acknowledge the centrality of industrial trends and economic factors, but will ideally transcend narrow economistic parameters to consider both the social implications of services growth, as well as the socio-cultural basis of advanced tertiarization, following the lead of progressive urban scholarship both in the atlantic and pacific spheres (moulaert and gallouj, ; kim et al., ) . more specifically, there is a clear need for conceptualization of trajectories of service sector development within the asia-pacific which embody experiences of differentiation and exceptionalism that abound within the region, as well as more widely observed features. beyond this important theoretical terrain, urban scholarship should address the relationships between the location of service industries and the reconfiguration of regional structure and the metropolitan space-economy. innovative new research in this realm includes larissa muller's work on business services in southeast asia, incorporating commentary on opportunities 'for localizing international investment' within the region (muller, ) . at the larger metropolitan scale, these models would position services as decisive influences on multinucleation, and would encompass spatial linkages between advanced services and manufacturing enterprises in regional production systems. at a more localized level, new urban spatial models should incorporate the emergence of emerging clusters of specialized services within reconstructed precincts of the inner city, including constituent ensembles of integrated services production networks. this should include research on the 'new economy' industries and cultural and creative activities which comprise the most recent phase of urban service industry development. finally, we can identify rich potential for socio-economic models of urban tertiarization that depict the role of services in social change within the region. there is an opportunity to investigate the hypothesis of a 'new middle class' (ley, ) as an ascendant social constituency among those asia-pacific cities which have experienced rapid growth in services. another research frontier concerns the new social divisions of service labour within asia-pacific cities, reflecting the convergence of culture, technology and urban milieu, observed in a growing number of new service production spaces within the region. then there is the overriding influence of global processes on the occupational and social structures of urban communities, including the role of mncs, the changing international division of production labour, innovation in telecommunications, and international migration. the extent to which these three powerful sets of forces-an ascendant new middle class of elite service workers, emerging social divisions of service labour, and globalization processes-influence social change and exacerbate social polarization tendencies within asia-pacific cities will surely assume greater theoretical and normative importance over the next decade and beyond. australian cultural diversity and export growth, office of multicultural affairs, canberra. asian development bank social transformations in the global city: singapore the coming of the post-industrial society services and the new economy: elements of a research agenda the service economy: export of services in the central puget sound region multimedia utopia? a geographical critique of high tech development in malaysia's supercorridor tropes of transboundary economic regions and the problems of greater china the informational city: information technology, economic restructuring, and the urban-regional process the expatriatisation of holland village building a competitive pearl river delta region: cooperation, coordination, and planning the yangtze delta metropolis. paper presented to a joint meeting of the chs-ubc asian the business of living in singapore modernism and the vernacular: transformation of public spaces and social life in singapore city of vancouver, . an economic strategy for vancouver in the s long-neglected services get new attention employment growth and change in the canadian urban system the new international division of labor, multinational corporations and urban hierarchy information technology and telecommunications policies in southeast asian development: cases in vision and leadership intelligent corridors: outcomes of electronic space policies office location: an urban and regional study report of the working group on tertiary industries, metropolis association economic development and producer services growth: the apec experience globalization, producer services and the asian city the planning response to urban service sector growth some planning implications of the expansion of the urban service sector london's and new york's response to the asian financial crisis the future of cities on the pacific rim transnational capital and the social construction of comparative advantage in southeast asia the 'new' tokyo story: restructuring space and the struggle for place in a world city the 'developmental state' and the asian newly industrialized economies globalization, intercity competition and civil society in pacific asia. keynote address to workshop on southeast asian urban futures, centre for advanced studies socializing the modern vietnamese family new strategies for technology development in japanese cities and regions economic restructuring in yokohama: from gateway port to international core city planning for technology development and information systems in japanese cities and regions planning for industrial restructuring in japan: the case of the chukyo region, centre for human settlements the death of shanghai's sotto. the globe and mail (toronto) the rise of the creative class world city formation: an agenda for research and action a world city and flexible specialisation: restructuring of the tokyo metropolis industrial districts and economic development in japan: the case of tokyo and osaka global reach, international relations section china's coastal cities: catalysts for modernization edge city: life on the new frontier the japanese technopolis programme: high-tech development strategy or industrial policy in disguise? the future of canadian city-regions: intersections of urban sustainability and competitive advantage megalopolis: the urbanized northeastern seabord of the united states urban centrality and the interweaving of quarternary activities the world cities, weidenfeld and nicolson the restructuring of urban economies: integrating urban and sectoral policies cities in civilisation, weidenfeld and nicolson the containment of urban england the human side of development: a study of migration, housing and community satisfaction in pudong new area, peoples republic of china chinese cities and china's development: a preview of the future role of hong kong the expanding role of hong kong as a service centre. hang seng economic monthly city profile: nagoya studying the city in the new international division of labor, department of sociology working papers industrial restructuring and the dynamics of city-state adjustments industrial restructuring, the singapore city-state, and the regional division of labour corporate regional functions in asia-pacific blood, thicker than water: networks of local chinese bureaucrats and taiwanese investors in southern china a profile of vancouver's service sector, monograph prepared for a meeting of the metropolis service industry working group service industries, economic restructuring and the spatial reconfiguration of asian pacific city-regions the transformation of canada's pacific metropolis: a study of vancouver reconstructed production landscapes in the postmodern city: applied design and creative services in the metropolitan core the new economy of the inner city: processes, patterns, and planning issues the role of office location in regional town centre planning and metropolitan multinucleation: the case of vancouver location, linkages and labor: the downtown complex of corporate activities in a medium size city the capital city development in japan from collective economy to collective economy? spatial transformation in the pearl river delta in the post-reform period culture and the city in east asia last colonial spatial plans for hong kong: global economy and domestic politics planning for qiandian (front shop): metroplan of hong kong a framework for exploring the hong kong-guangdong link corporate strategies for the asia-pacific inner city neighbourhood development redevelopment before development: asian cities prepare for the pacific century, asian urban research network, centre for human settlements vietnam's urban edge: the administration of urban development in hanoi the myth of continents: a critique of metageography the new middle class and the remaking of the central city the service sector and metropolitan development in canada personal communication re: dr leilei li's project on cultural industries in shenzen changing theoretical perspectives on urbanization in asian developing countries china's industrialization with controlled urbanization: anti-urbanism or urban-biased? identity, mobility, and the making of the chinese diasporic landscape: the case of hong kong the persistence of proto-proletariat: occupational structures and planning of the future of third world cities labour force change and mobility in the extended metropolitan regions of asia the emergence of desakota regions in asia: expanding a hypothesis reconstructing the southeast asian city in a post-modern era. paper presented to the workshop on southeast asian futures, centre for advanced studies footprints in space: spatial restructuring in the east asian nics - the mega-urban regions of southeast asia from corridors to intercity networks: the role of emerging urban systems in building regional networks in northeast asia. paper presented to the fifth annual ubc-ritsumeikan seminar the urban restructuring process in tokyo in the s: transforming tokyo into a world city urban development and planning in beijing metropolitan region restless landscapes: spatial economic restructuring in china's lower yangzi delta. phd dissertation northeast asian economic cooperation and and the tumen river area development project tokyo as a global city the locational geography of advanced producer firms: the limits of economies of agglomeration advanced business services in southeast asia: an opportunity for localizing international investment the development and transformation of guangzhou, centre for urban and regional studies the economic transformation of american cities editor's preface, special issue of asia pacific viewpoint australia's changing economic geography: a society dividing globalization and the production of new urban spaces: pacific rim mega-projects in the late th century globalizing shanghai: the global intelligence corps and the building of pudong globalization and urban change: capital, culture, and pacific rim mega-projects where there is sugar, there are ants: planning for people in the development of batam, indonesia pacific asia in the global system economic and industrial development and its implications in the jakarta-bandung mega-urban area, department of regional and city planning making democracy work: civic traditions in modern italy southeast asia: the human landscape of modernization and development japan's world cities international transport and communications interactions between pacific asia's emerging world cities the global city high technology industry and territorial development: the rise of the orange county complex metropolis: from the division of labor to urban form the cultural economy of cities the cultural economy of cities global city-regions planning for cities and regions in japan ten kilometres of dot.com haven producer services development and trade: malaysia and asean in the uruguay round the new economy, allenheld and osmun territories, flows, and hierarchies in the global economy worlds of production: the action framework of the economy the autumn of central paris: the defeat of town planning - from export center to world city: planning for the transformation of hong kong the internationalisation of producer services and the integration of the pacific basin property market the economies of southeast asia: before and after the crisis hong kong's economic prospect in a changing relationship with china: a speculative essay services in asia and the pacific: selected papers, united nations asean-eec trade in services corridors: a theory of urban system urban spatial structure in a transitional economy: the case of guangzhou development of land use and urban planning of guangzhou, centre for urban and regional studies bangkok's restaurant sector: gender, employment and consumption shanghai: transformation and modernization under china's open policy building a competitive pearl river delta region: cooperation, coordination, planning portraits of places: history, community and identity in singapore changing southeast asian cities: urbanization and the environment in international perspective the culture of cities sources for this project included extensive site visits and field trips to cities within the asia-pacific; communication with numerous colleagues, and key informants; participation in conferences and special workshops; and a review of several distinct literature domains, including the services research literature, asian urban studies, and the urban change and transformation scholarship. visits to chinese and southeast asian cities were undertaken as part of a much larger asian urban research project managed by the ubc centre for human settlements, supported by the canadian international development agency (cida centre of excellence grant # -s ). this study includes references to research undertaken by colleagues within partner institutions in asia, as well as theses produced by ubc graduate students supported by this cida grant. site visits and study tours of japanese cities were enabled by grants from the japan foundation, the japanese ministry of education, and the ubc hampton research fund. fieldwork in san francisco was supported in part by a grant from the ubc vice-president's (research) discretionary fund. an exploratory workshop on 'service industries and new trajectories of urban development within the asia-pacific', involving many of the leading international scholars in service industry scholarship and in asian urban studies was convened at the university of british columbia in march, , generously supported by the peter wall institute for advanced studies, ubc. this workshop significantly contributed to new knowledge on the role of service industries in processes of urban change within the asia-pacific, substantially informed this current paper, and generated manuscripts to be included in a new book to be co-edited by peter daniels (university of birmingham), kong chong ho (national university of singapore), and me.i also want to acknowledge the generosity of the centre for advanced studies at the national university of singapore in making possible my sojourn as visiting scholar in july of . this enabled me to liaise with (new and existing) colleagues, to conduct fieldwork, and to present a selection of findings to a cas colloquium. in particular i would like to express my appreciation to brenda yeoh, k.c. ho, peggy teo, and kris olds of cas (the latter now at the department of geography, university of wisconsin at madison), and to henry yeung of the nus department of geography.finally, i want to acknowledge the essential contributions of ubc colleagues. michael leaf (director, centre for southeast asian research, and faculty associate at chs) and david edgington (director, centre for japanese research, and associate professor in the department of geography) have generously contributed many expert insights on development planning issues in china, southeast asia, and japan. i am very grateful indeed for the administrative support of ms karen zeller, and the unfailingly professional and patient assistance of ms sharon kong in the preparation of this manuscript; for the high levels of technical assistance provided by ms christine evans; and for the excellent cartographic services of mr eric leinberger of the ubc department of geography. key: cord- - ka y y authors: chau, pui hing; li, wei ying; yip, paul s. f. title: construction of the infection curve of local cases of covid- in hong kong using back-projection date: - - journal: int j environ res public health doi: . /ijerph sha: doc_id: cord_uid: ka y y this study aimed to estimate the infection curve of local cases of the coronavirus disease (covid- ) in hong kong and identify major events and preventive measures associated with the trajectory of the infection curve in the first two waves. the daily number of onset local cases was used to estimate the daily number of infections based on back-projection. the estimated infection curve was examined to identify the preventive measures or major events associated with its trajectory. until april , there were confirmed local cases. the infection curve of the local cases in hong kong was constructed and used for evaluating the impacts of various policies and events in a narrative manner. social gatherings and some pre-implementation announcements on inbound traveler policies coincided with peaks on the infection curve. the world health organization (who) declared the coronavirus disease (covid- ) as a pandemic [ ] . it has been demonstrated that social distancing, contact tracing, patient isolation, early diagnosis, city lockdown, and travel restrictions were effective measures in slowing down the spread of covid- [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] . for the public to be prepared for dramatic changes, both physical and mental, a pre-implementation announcement is usually made. depending on the actual time of the announcement, the time gap ranges from less than h to a couple of days. to date, the impact of this window of infection and its unintended consequences have not been investigated. apart from using simulations under the susceptible-exposed-infectious-removed (seir) model, an examination of the trajectory of the epidemic curve provides some insight into the impacts of various policies and events in a narrative manner. with one exception [ ] , to date, those investigations on the effectiveness of preventive measures were based on epidemic curves mainly constructed using the date of diagnosis or onset [ , , [ ] [ ] [ ] [ ] [ ] [ ] . the estimated mean incubation period of the covid- varies from . to . days across studies [ ] . the epidemic curve based on the infection date, however, would be more accurate to assess the effectiveness of various measures and the impacts of the events. as the date of infection is unobservable, it has to be estimated. the back-projection technique was originally developed to construct the infection curve for the human immunodeficiency virus (hiv)/acquired immune deficiency syndrome (aids) epidemic [ , ] . in , the authors applied the back-projection method to the severe acute respiratory syndrome (sars) epidemic [ ] . the current study constructed an epidemic curve based on the date of infection estimated by the back-projection method to minimize the effects of the incubation time and reflect the possible impacts of various measures and events better. up until august , hong kong had confirmed covid- cases with deaths. from january to april , most of the cases were imported and clustered with known sources, and were considered as the first two waves of the infection. the third wave started in july, still continuing at the time of this publication. most of those cases were local, and the sources of many of which were unknown. the present study focused on the first two waves of local infections in hong kong. all the government announcements were systematically recorded on the official website, thus providing reliable information on the pre-implementation announcement dates and the implementation dates of the preventive measures. this provided a trusted source to examine the possible association between the pre-implementation announcements and the infection curve in a narrative manner. our objective was to estimate the infection curve of the local cases of the first two waves of covid- in hong kong using the back-projection method and explore the effectiveness of the preventive measures, including the possible impacts of the pre-implementation announcements by the local government. the daily number of confirmed cases of covid- reported by april was obtained from the website of the centre for health protection, hong kong (https://www.chp.gov.hk/). a confirmed case was defined as a person with laboratory confirmation of covid- infection, irrespective of clinical signs and symptoms [ ] . as the date of infection of the imported cases cannot reflect the impact of the preventive measures implemented locally, all imported cases were excluded from the analysis. until april , there were confirmed cases in hong kong, of which were local cases and included in this study. among the cases, were asymptomatic and the date of onset was proxied by the date of report in the primary analysis. a sensitivity analysis was performed by excluding the asymptomatic cases. an infected person goes through an incubation period before the onset of the symptoms. the time when the symptoms appear is the onset time. the term "onset cases" was used to refer to the cases with onset of the symptoms on a particular day. there was also a delay between the onset of symptom(s) and the confirmation of cases. figure shows the temporal relation between infection, onset, and confirmed cases. in this study, daily onset cases were used for the back-projection method. let t = , , . . . , τ denote the days, where t = denotes january . as the earliest onset date was january , it was assumed that there was no infection days prior to that date. furthermore, this was consistent with the fact that the earliest arrival date of imported cases was january . as the last time point was april , τ had been set to . the daily mean number of onset covid- cases (µ t ) was expressed in terms of the daily mean number of infection (λ s , s= , . . . , t) by the convolution equation: where f t-s,s is the probability function of the incubation period, that is, the probability that an individual infected at time s developed a symptom after a period of length t-s. in other words, infected cases on day went through an incubation period of t- days with the probability specified by the probability function of the incubation period and had onset of symptoms on day t; then infected cases on day went through an incubation period of t- days; infected cases on day went through an incubation period of t- days and so on, up to infected cases on day t that went through an incubation period of days. the sum of all these cases was the total number of onset cases on day t. based on a recent meta-analysis on the incubation period established from eight studies [ ] , the probability function of the incubation period of covid- was taken as a log-normal distribution with scale and shape parameters of . and . , respectively. this corresponded to a mean of . days, a median of . days, and a th percentile of . days. the ems (estimate-maximize-smooth) algorithm was used to estimate the daily number of infection and pointwise % confidence interval was constructed by the bootstrap procedure. details of the back-projection method are reported elsewhere [ , ] . python was used for running the algorithm [ ] . the estimated infection curve was closely examined in relation to the major events and policies announced and/or implemented by the local government. the major events and policies were obtained from the official websites (www.info.gov.hk/gia/ and www.news.gov.hk). table s shows the selected government policies and major events in the period under examination. the number of covid- infections over this period was estimated to be . figure gives the estimated daily number of covid- infections, the pointwise % confidence intervals on the estimated infection number, and the observed daily number of onset cases for the period from january to april . it was estimated that the first infection occurred around january , roughly four days after the arrival of the first imported case on january . the highest peak was estimated around mid-march , which was in the middle of the second wave of infection which started in march. zero infection was estimated since april . in the first wave, the estimated infected cases in late january could be mainly attributable to the social and family gatherings around the chinese new year. it was reported from contact history tracing that infected people attended a family dinner in north point on january , infected people attended a family gathering at a party room in kwun tong on january , and infected people visited a buddhist worship hall in north point between january and early february . in the second wave, it was reported that there were two large-scale gatherings on march , one involved guests at a wedding party and the other involved over guests at a private party. a total of confirmed cases were reported from those two gatherings. this was consistent with the peak in the infection curve on march . furthermore, staff and customers of some pubs and bar areas were infected, and more confirmed cases had epidemiological link to these cases. the onset date of this infection cluster was reported to be from march to april , implying infection from around early march to early april. on march , it was reported that people went to a karaoke and all were infected. on january , an announcement was made to ban inbound travelers who had visited the hubei province in the past days prior to its actual implementation at midnight on january . from to january , numerous policies were announced and implemented, including activation of the emergency response level, cancellation of large-scale events, quarantine of close contacts of confirmed cases, health advice to residents returning from the hubei province and other parts of china, suspension of non-emergent government services, closure of public facilities, home office arrangement for civil servants, and substantial reduction of traffic between mainland china and hong kong. as the peak of the first wave around - january was dominated by cluster infections during social gathering, it was difficult to observe potential influence from these policies. the announcement on february about mandatory quarantine for inbound travelers who had been to emilia-romagna, lombardy, or the veneto regions in italy or iran in the past days coincided with a local maximum. the curve, however, slightly went down after implementation of the policy on march . there was also an announcement on march about the health declaration requirement on all inbound travelers effective from march . the curve declined slightly forthwith. the peaks on - march and - march were the key features of the second wave. during - march , some non-emergent government services and public facilities resumed, and civil servants returned to work in the office. various policies on inbound travelers were announced and implemented during that period. however, their associations with the infection curve might be masked by the cluster infections in the wedding party, private party and the pubs and bar areas during the same period. on march , the government announced mandatory quarantine on inbound travelers from the whole of italy, france (bourgogne-franche-comte and grand est), germany (north rhine-westphalia), japan (hokkaido), and spain (la rioja, madrid, and pais vasco). this announcement coincided with the rise on the infection curve. on march , the government further announced mandatory quarantine on inbound travelers who had visited the schengen area countries. moreover, on march , mandatory quarantine was announced on all inbound travelers who had traveled to ireland, the united kingdom, the united states, and egypt. then, on march , mandatory quarantine was announced for all inbound travelers from all overseas places, which activated the downward trend again. starting from march , inbound travelers with symptoms of upper respiratory symptoms were tested at designated test centers and they had to wait for the results. for the second time, non-emergent government services and public facilities were closed from march , and the civil servants resumed to home office arrangement again. after implementation of these policies, the infection curve declined. against the declining trend, the infection number rebounded on march . however, the increase appeared to be not related to the pre-implementation announcements on march , which involved (i) strict operational instructions on the catering business (limiting the number of seats to half of the capacity, minimum distance of one and a half meters between tables, and a maximum of four seats per table); (ii) closure of scheduled premises (including amusement game centers, bathhouses, fitness centers, places of amusement, places of public entertainment, and party rooms); and (iii) ban of groups over four people in public places. the first two policies were implemented on march and the third policy was implemented on march . furthermore, closure of karaoke, mahjong-tin kau, and nightclub establishments was announced on april and closure of bars and pubs was also announced on april , and implemented on and april , respectively. after implementation of all those policies, the infection number continued to fall to zero by april . the sensitivity analysis that excluded the asymptomatic cases ( figure s ) gave a similar trajectory of the infection curve. it was noted that the local maxima from february to march and from march to april were not observed in the sensitivity analysis that excluded the asymptomatic cases. the peak on march in the sensitivity analysis was lower than that which included the asymptomatic cases. it might be that those infected in those periods were mostly asymptomatic. the current study constructed the infection curve of local confirmed covid- cases in hong kong. from studying the estimated curve closely with the major events and preventive measures, it was observed that a strict mandatory quarantine order on inbound travelers coincided with the decline from the peak in the infection number. however, some pre-implementation announcements of such policies and social gatherings corresponded with sharp increases in the infected cases. the closure of public facilities and home office arrangement might have helped to slow down the spread. it is common practice around the globe to pre-announce government policies. in hong kong, the press conference was usually held at : pm. for policies to be implemented the following day, such an announcement would only leave several hours before the actual implementation. to stir up reactions, such a short period may not be sufficient. for transportation from overseas countries to hong kong, more time is needed for preparation. thus, the announcements of mandatory quarantine on people returning from overseas were made over h prior to implementation. instead of using the time to well plan for the -day quarantine, those from overseas, however, rushed back to hong kong to avoid the mandatory quarantine. it was reported that confirmed imported cases (the largest daily imported cases) entered hong kong on march , just before implementation of the mandatory quarantine policy. to make things worse, social gathering still went on during that period when cluster infections related to some bars and pub areas were reported. it is understandable though for the government to announce the policies in advance to allow the people to be better prepared. however, in hong kong, many residents rushed back before the implementation to avoid the mandatory quarantine, thus increasing the risk of transmission in the community. to minimize the opportunity of infection, pre-implementation announcements should be made as close to the implementation date as possible. meanwhile, comprehensive support plans for those being quarantined and groundwork should simultaneously be in place. quarantines on inbound travelers appeared to be effective. according to a study in singapore, rapid identification and isolation, quarantine of close contacts, and active monitoring of other contacts were effective measures in controlling covid- [ ] . nevertheless, it should be noted that quarantine should be combined with other public health measures to achieve the best result [ ] . quarantine polices are important and overall well-being should be catered for too. during the sars epidemic, people felt isolated and hopeless, which resulted in a rise in the suicide rate [ , ] . while controlling the spread of the epidemic, the mental well-being of the residents should also be taken care of [ ] . fortunately, with the many social media devices, social connectedness and emotional closeness can still be maintained when practicing physical distancing. it is important to ensure those quarantined do not feel left out or forgotten. meanwhile, it appeared that screening for covid- at the airport might not be effective enough in catching a significant proportion of cases [ ] . however, sample testing for all inbound travelers seemed to work well in preventing the cases from entering the hong kong community. since such a policy was in force together with the mandatory quarantine policy, its effect alone could not be evaluated. the suspension of non-emergent government services, closure of public facilities, and home office arrangement for civil servants at the end of january coincided with the drop in the number of covid- infections at the end of january. moreover, resumption of these services and work at the office in early march seemed to correlate with an increase in the infection. subsequently, the suspension of these services and home office arrangement were implemented again at the end of march. the implementation of other policies included the suspension of education and schools. however, as these policies were implemented concurrently, an evaluation on the individual effectiveness of each policy was not possible. indeed, a review suggested that the effect of school closure was less than that of other social distancing interventions [ ] . this could be true in view of an example in taiwan where schools and offices were not closed, yet the infection could still be maintained at a low level. it has also been reported that highly effective contact tracing and case isolation were sufficient to control a new outbreak of covid- [ ] . in this regard, hong kong has been performing contact tracing exceptionally well, nonetheless, its effect also could not be assessed in the current study. the strength of this study was the estimation of the infection curve based on the back-projection method. the limitation of this study was that the date of onset was subject to recall bias, and a proxy date of onset was assumed on asymptomatic patients. a sensitivity analysis was conducted by excluding the asymptomatic cases, and the trajectory of the infection curve remained roughly the same. an assumption made on the incubation period might also affect the estimated infection curve. nevertheless, this study utilized the pooled estimate from a meta-analysis based on eight studies [ ] . this study was a narrative study, and causality cannot be assessed. in addition, if there were more than one policy or event occurring in parallel, it would be difficult to distinguish their impacts. at the same period, there were also social events such as healthcare on strike, protests for various reasons, and panic purchase of food and toilet paper, which involved the gathering of people and reduced social distancing, yet this study did not analyze their impact. future studies might consider using the estimated infection curve to assess the effectiveness of various preventive measures and events using the quantitative approach. to conclude, the infection curve of covid- could be constructed by the back-projection method. the findings of this study were consistent with previous studies on the effectiveness of some preventive measures. this study suggests that social gatherings and policy announcements and implementation sometimes coincide with changes in the infection curve; however, prospective studies designed to evaluate causality are needed to further understand this observation. rolling updates on coronavirus disease (covid- ) impact assessment of non-pharmaceutical interventions against coronavirus disease and influenza in hong kong: an observational study feasibility of controlling covid- outbreaks by isolation of cases and contacts the effectiveness of quarantine of wuhan city against the corona virus disease (covid- ): a well-mixed seir model analysis interventions to mitigate early spread of sars-cov- in singapore: a modelling study evaluation of the effectiveness of surveillance and containment measures for the first patients with covid- in singapore quarantine alone or in combination with other public health measures to control covid- : a rapid review association of public health interventions with the epidemiology of the covid- outbreak in wuhan, china effectiveness of the measures to flatten the epidemic curve of covid- . the case of spain evaluation of the lockdowns for the sars-cov- epidemic in italy and spain after one month follow up description of covid- cases along with the measures taken on prevention and control in zhejiang covid- social distancing in the kingdom of saudi arabia: bold measures in the face of political, economic, social and religious challenges backcalculating the incidence of infection with covid- on the diamond princess incubation period of covid- : a rapid systematic review and meta-analysis of observational research a method of non-parametric back-projection and its application to aids data reconstructing the incidence of human immunodeficiency virus (hiv) in hong kong by using data from hiv positive tests and diagnoses of acquired immune deficiency syndrome monitoring the severe acute respiratory syndrome epidemic and assessing effectiveness of interventions in hong kong special administrative region global surveillance for covid- caused by human infection with covid- virus (interim guidance) python reference manual; createspace the impact of epidemic outbreak a revisit on older adults suicides and severe acute respiratory syndrome (sars) epidemic in hong kong physical distancing and emotional closeness amidst covid- ncov working effectiveness of airport screening at detecting travellers infected with novel coronavirus ( -ncov) school closure and management practices during coronavirus outbreaks including covid- : a rapid systematic review key: cord- -mmlwh u authors: tso, ivy f.; park, sohee title: alarming levels of psychiatric symptoms and the role of loneliness during the covid- epidemic: a case study of hong kong date: - - journal: psychiatry res doi: . /j.psychres. . sha: doc_id: cord_uid: mmlwh u public health strategies to curb the spread of the coronavirus involve sheltering at home and social distancing are effective in reducing the transmission rate, but the unintended consequences of prolonged social isolation on mental health have not been investigated. we focused on hong kong for its very rapid and comprehensive response to the pandemic and strictly enacted social distancing protocols. thus, hong kong is a model case for the population-wide practice of effective social distancing and provides an opportunity to examine the impact of loneliness on mental health during the covid- . we conducted an anonymous online survey of residents in hong kong to examine psychological distress in the community. the results indicate a dire situation with respect to mental health. an astonishing . % ( % c.i. = [ . %, . %]) of the respondents reported clinical levels of depression, anxiety, and/or stress. moreover, . % ( % c.i. = [ . %, . %]) of the respondents were showing signs of psychosis risk. subjective feelings of loneliness, but not social network size, were associated with increased psychiatric symptoms. to mitigate the potential epidemic of mental illness in the near future, there is an urgent need to prepare clinicians, caregivers and stakeholders to focus on loneliness.  strict social distancing, implemented widely to curb the spread of covid- , has the unintended consequences of prolonged social isolation and adverse impact on mental health.  we conducted an online survey to examine the impact of loneliness on mental health during covid- in hong kong, a model case for the population-wide practice of effective social distancing.  an astonishing . % of the respondents reported clinical levels of depression, anxiety, and/or stress, and . % were showing signs of psychosis risk.  loneliness, but not social network size, explained . % to . % of variance in these psychiatric symptoms.  to mitigate the potential epidemic of mental illness in the near future, there is an urgent need to prepare clinicians, caregivers and stakeholders to focus on loneliness. the corona virus disease , first started in china in december , has spread across the globe within a few months and was declared a pandemic on march th , . many mental health professionals and scholars predict that the pandemic will have profound and long-lasting impact on mental health worldwide (holmes et al., ) . even prior to the current pandemic, mental illness was a global public health issue. according to the global burden of diseases study, psychological disorders were the fifth leading cause of disability worldwide . anxiety disorders and major depressive disorder each affected over million people, and acute schizophrenia carried the highest disability weight of all diseases vos et al., ) . based on past observations of surges of psychiatric disorders and deaths by suicide following large-scale, life-threatening epidemics-for example, sars in (cheung et al., mak et al., ) , the - ebola epidemic (jalloh et al., ) , and the - influenza pandemic (mamelund, ; wasserman, ) -and the unprecedented scale of the covid- pandemic, the extraordinary societal burden of mental illness is likely to grow further and rapidly in the near future. many expect a significant increase in the incidence of posttraumatic stress disorder (ptsd), depression, anxiety, substance use, suicide and other mental disorders, post-covid among the survivors, their caregivers, and healthcare workers (holmes et al., ) . indeed, preliminary results from china and italy confirm the high prevalence of ptsd, anxiety, depression, and perceived stress among the survivors of covid- , and healthcare workers (bo et al., ; rossi et al., ) . the mental health impact of covid- will not be limited to those who are directly confronting (or have confronted) the disease. to contain the spread of the virus, nearly every country has implemented unprecedented levels and scales of quarantine, physical distancing, and even community lockdown. although effective in flattening the epidemic curve (matrajt and leung, ) , these public health strategies severely disrupt daily social life and limit interpersonal interactions with adverse consequences of social disconnection and loneliness, which play a central role in poor physical and mental health outcomes (cacioppo et al., ) , loneliness has been linked to premature death from stroke and cardiovascular diseases (valtorta et al., ) , altered expression of genes involved in inflammation and antiviral response (cole et al., ) , as well as increased depression, generalized anxiety disorder, panic disorder, suicide risk and psychosis (badcock et al., ; beutel et al., ) . with the prolonged social distancing related to covid- , the general public will soon experience a surge in physical and mental illness. indeed, emerging data from china suggest increased incidence of mental illness among the general population following the covid- epidemic (gao et al., ; wang et al., ) . preliminary data also support the association between increased loneliness and greater depression (killgore et al., ) , although this relationship may be moderated by other psychological factors (shrira et al., ) . further studies are needed to confirm the role of loneliness in mental health during covid- with important factors likely impacting wellbeing controlled, and extend the investigation from depression and anxiety to other mental health concerns such as substance use and symptoms indicative of more severe disorders (e.g., psychosis). the present study examined wellbeing of the general public following prolonged social distancing during the covid- pandemic, and the role of loneliness and social network. we selected one of the first regions affected by covid- with strictly enforced quarantine and social distancing protocols since late january -hong kong. hong kong is a special , ) . however, this early rapid response also means that the community has been living in prolonged social isolation since january . we conducted an online survey of hong kong residents between march st and may th , to assess the physical and mental wellbeing after the city had implemented widespread social distancing for two months. we expected to observe high rates of common psychiatric symptoms (depression, anxiety, stress) as well as symptoms indicating emergence of severe mental illnesses (psychosis risk). furthermore, we expected that high levels of loneliness would be observed and would significantly explain health and mental health status, even after controlling for other key factors likely impacting wellbeing. respondents of this online survey were adults (age or above), regardless of ethnic backgrounds and nationalities, currently residing in hong kong. a total of unique visitors viewed the survey overview page in the period from march st , to may th, , out of which were eligible for the survey by answering or above for age and selecting "yes" or "part of the time" for the question of hong kong residence. of the eligible participants, ( . %) completed at least the demographics section and ( . %) completed the entire survey. only respondents completed at least the demographics section (n = ) were included in the analyses below. these respondents on average completed . % (median = %; sd = . %) of the survey. the survey was available in two languages (traditional chinese and english) and was run on the qualtrics online platform (provo, ut). links to the survey were circulated on social media, local online forums or websites, and via words of mouth to reach the target population of hong kong residents. the survey was anonymous as no identifying information (e.g., name, date of birth, contact information, ip address) was asked or recorded. the median time respondents spent on the survey was min s. this study received exempt determination from the university of michigan institutional review board (irb# hum ). the survey consisted of questions assessing participants' demographics, general health, mental health, loneliness, and social network. the demographics and general health questions used in this survey (english version) can be found in supplementary information . items related to mental health, loneliness, and social network can be found in prior publications (detailed below). for mental health, the -item version of the depression anxiety stress scales (dass- ) (p. f. taouk moussa et al., ) was used to assess depression, anxiety, and stress levels. scores for depression, anxiety, and stress were calculated for each individual and classified into severity levels (normal, mild, moderate, severe, or extremely severe) according to the published norms (s. h. . the -item version of the prodromal questionnaire (pq- ) (ising et al., ) was used to screen for psychosis risk symptoms. for each individual, total score (i.e., number of items endorsed) and distress score (sum of distress related to endorsed items) were computed. a total score of or higher was considered screened positive for psychosis risk syndrome (ising et al., ) . the ucla loneliness scale (russell, ) was used to assess the respondent's perceived loneliness. the social network index (sni) (cohen, ) was used to measure diversity (i.e., number of social roles) and size (number of people with whom the respondent has regular contact) of social network. respondents' demographics, general health, and mental health (dass- and pq- scores), loneliness (ucla total score), and social network (sni diversity and size scores) were examined with descriptive statistics. to understand the relationship of loneliness and social network to health and mental health, hierarchical regression analyses were conducted. this model comparison approach allows us to examine whether loneliness and/or social network can explain health and mental health above and beyond other demographic, psychological, and socio-political factors that likely have influence one's wellbeing. these include age, sex, exposure to domestic abuse, and worries about covid- . given the current political context of hong kong where the residents had already been exposed to prolonged societal unrest and distress, we also considered the level of participation in the protest as a potentially influential factor. therefore, in step of the hierarchical regression analyses, age, sex (two dummy coded variables: female, and no response to question of sex), frequency of domestic violence/abuse, level of concern about covid- , and level of participation in the protests were entered as predictors into the reduced model. in step , stepwise method was used to add loneliness (ucla total score) and social network (sni diversity and size) measures as predictors into the full model. the dependent variables included: ) self-report overall health; ) numbers of days (over the past days) in which physical health was not good; ) numbers of days in which mental health was not good; ) number of days in which poor physical or mental health affected usual activities; ) number of days in which pain affected usual activities; ) number of days in which the respondent felt worried, anxious, or tense; ) dass- depression; ) dass- anxiety; ) dass- stress; ) pq- total score; and ) pq- distress score. since level of participation in the hong kong protests was not a significant predictor when included in any of the reduced or full models, and that nearly % of the respondents had a missing value on the item of (they chose not to answer the question), we removed this variable from the regression analyses to increase the sample size. the results of the regression analyses with or without this variable were virtually identical. we only report the results without this predictor variable below. because some respondents did not complete all the questions, the percentages reported below were calculated using the number of respondents completed the corresponding section as the denominator. summary of the respondents who completed the demographics section is presented in comparatively, concern about the current covid- epidemic was much higher, with ( . %) of the respondents expressing moderate or extreme concern (figure ). respondents completed the general health section. for self-perceived overall health, rated on a - scale (representing "excellent," "very good," "good," "fair," and "poor"), most respondents ( . %) reported "good" or better (median = . , mean = . , sd = . ). about a third ( . %) endorsed one or more of the following types of illnesses in the past days: head cold or chest cold ( . %); gastrointestinal illness with vomiting or diarrhea ( . %); flu, pneumonia, or ear infections ( . %); an ongoing or chronic medical condition ( . %). only . % were in mandatory or self-quarantine related to covid- (median duration = days). none were in inpatient hospital care. few ( . %) of the respondents were cigarette smokers (mean = . packs/day, sd = . ) or alcohol drinkers ( . %; mean = . drinks/week, sd = . ). however, among those who smoke or drink, many endorsed having been smoking ( . %) or drinking ( . %) more than usual in the past days. the number of days in which various health-related problems occurred over the past days are summarized in figure . overall, the respondents reported more days affected by mental health issues than by physical health issues. respondents completed the ucla loneliness scale. the mean score was . (median = . ; sd = . ), more than one standard deviation above the published norms obtained from samples of college students and nurses in north america (russell, ) . respondents completed the social network index, reporting a mean number of social roles of . (median = . , sd = . , range = - ). the mean number of people with whom the respondents have regular contact (i.e., at least once every weeks) was . (median = . , sd = . , range = - ). the model statistics of the hierarchical regression analyses are summarized in table ; coefficients statistics are presented in supplementary information (table s ). briefly, even after controlling for the effects of key variables that could impact health and mental health (age, sex, domestic violence exposure, and level of concern about covid- ), loneliness significantly explained variance (r -change ranging from . % to . %) in all of the health and mental health measures (except the number of days in which usual activities were affected by pain). this amount was even higher for models using scores of validated scales of psychiatric symptoms (i.e., dass and pq ) as the dependent variable, with r -change ranging from . % to . %. social network diversity and size did not significantly explain any of the health and mental health measures. the findings of this survey paint a very disconcerting picture of the mental health status among people in hong kong during the covid- pandemic. although many respondents reported overall good physical health and few days in the past month in which they were affected by physical health or pain issues, they suffered mental health issues frequently in that they experienced poor mental health or feeling worried, anxious or tense, on average, in more than one-third of the time over the past month. their responses to validated scales of psychiatric symptoms suggest that almost two-thirds ( . %) reported clinical levels of depression, anxiety, and/or stress. population-wide incidence and prevalence of psychiatric disorders prior to covid- have been tracked by the large community-based studies of mental health lee et al., ) ; weighted prevalence was estimated at . % for any past-week for any psychiatric condition, with mixed anxiety and depressive disorder being the most frequent diagnoses. therefore, our results from the current survey indicate a significant increase in the risk for mental illness in the general population. yet more concerning is the high rate ( . %) of elevated risk for a psychotic disorder observed in this study. previous studies using the same measure found only . % of help-seeking young people in north america screened positive for psychosis-risk (ising et al., ) . a prior population-based household survey for mental disorders estimated a lifetime prevalence of all psychotic disorders to be approximately . % among the chinese adult population in hong kong (chang et al., ) ; this estimate is similar to the prevalence reported globally, suggesting that the elevated psychosis risk found in this study was not due to a higher "baseline" psychosis risk among hong kong people. this is a population with low rates of smoking ( . %) or drinking alcohol on a regularly basis ( . %). while the smoking rate in this sample was similar to that reported in the census ( . %) (census and statistics department, ), the drinking rate was much higher than the . % reported in the population health survey / (centre for health protection, ). among those who smoke or drink alcohol regularly, many reported having been smoking ( %) or drinking ( %) more heavily in the past month. taken together, these findings indicate that the societal impact of the covid- in hong kong extends beyond the illness itself and well into the future, with sharp increases in the risk for depression, anxiety, stress, psychosis, and substance use. in addition to psychiatric symptoms, level of loneliness was very high in this hong kong sample: it was one standard deviation elevated compared with samples of similar education attainment (college students and nurses) in north america (russell, ) . furthermore, loneliness significantly explained physical and mental health across measures, even after accounting for the effects of other important variables (age, sex, domestic abuse/violence frequency, and level of concern for covid- ). the only health measure not significantly explained by loneliness was the number of days affected by pain, likely due to the very low frequency of pain in this sample. whilst the prevalence of psychological distress found in this sample during the pandemic is daunting, our finding that loneliness is playing a central role may give us a handle to address this public health emergency at a societal level. to mitigate the potential epidemic of mental illness in the near future, there is an urgent need to prepare clinicians, caregivers and stakeholders to focus on loneliness. reducing loneliness could result in reduction of mental illness across all diagnostic categories. our finding that social network size (number of social roles, and number of people in the social network) failed to explain any of the health and mental health measures suggests that it is the quality rather than quantity of interpersonal relationships that matters. therefore, interventions that can strengthen social connectedness (e.g., training in communication and social skills, consistent group activities) may exert larger impact than focusing only on increasing the amount of social encounters. furthermore, interventions need to be implemented at a broad societal level rather than for a small fraction of the population. creative solutions, including those leveraging technology, are likely needed to help achieve this goal. it is important to remember that individuals with preexisting psychiatric conditions or those who were already marginalized in society are likely to be impacted even more by the social distancing protocols introduced to reduce the transmission rate of the virus and economic aftermath of the pandemic (tsai and wilson, ; yao et al., ) , and we must deploy more resources and social capital to address the mental health needs of people disproportionately affected by the pandemic. ongoing pro-democracy movement (reuters, ) , which has been assailed by an unprecedented level of violent crackdown (amnesty international, ; time, ) and persecution by the authorities (pang, ) . this sociopolitical context must be considered when interpreting the findings of this study. the city was already embattled with a mental health crisis before the pandemic. a study conducted in late , just before the covid- epidemic in hong kong, showed high rates of probable posttraumatic stress ( . %) and depression ( . %) among the residents, especially the younger (age - ) cohort who show higher level of support for the protests (ni et al., ) . the pandemic further deteriorated people's mental health, not only through prolonged social distancing, but also economic decline (lam, a) , surge of unemployment rate (lam, b) , and public mistrust of the government (marlow and hong, ; radio television hong kong, ) . therefore, the alarming covid- related mental health status found in this study was likely amplified by ongoing societal problems, some of which are in common with other countries and some are unique to hong kong. this study has several limitations. the sample was relatively young and highly educated, unlikely to be fully representative of the hong kong population. this was a cross-sectional study and lacked longitudinal data to track changes in mental health over time during the pandemic. however, the rates of psychiatric symptoms founded in this study were higher than the estimates reported in a study of a representative sample conducted in december (ni et al., ) , just before the first confirmed case of covid- was reported. this provides some preliminary evidence for the adverse consequences of covid- on mental health across broad domains including psychosis. additionally, although level of participation in the hong kong protests was not a significant predictor of mental health status in the regression analyses, it should be noted that a non-trivial proportion of the respondents (~ %) chose not to answer this question. it is possible that respondents who participated frequently in the protests were more likely to skip this question because they were worried about political or legal repercussions. however, it is also possible that those who never or rarely participated in the protests tended to skip this question because of social desirability (the protests are widely supported by people in hong kong). it is unclear whether the data of this question were missing at random or not. in so far as we could test from the available data, we could only conclude that level of participation in the hong kong protests did not predict health/mental health status. this may be because the political crisis and social unrest affected everyone negatively regardless of one's political orientation. obviously, this result applies only to this sample at this given point in time. the political situation has significantly worsened since our survey, so it is possible that the impact of participation in political protests has changed as well. finally, the survey data were collected mostly in april ; it is unknown how mental health outcome would be impacted by the lifting of social distancing protocols worldwide, potentially followed by a second-or even third-wave of the pandemic. close monitoring of the mental health impact of this pandemic is warranted. to conclude, this study investigated the mental health status of ordinary citizens and the impact of loneliness in a city that was one of the first regions that practiced population-wide social distancing during the covid- pandemic. the results indicate a dire situation with respect to mental health, with highly elevated rates of significant psychiatric symptoms including depression, anxiety, stress, and signs of psychosis risk. subjective feelings of loneliness, but not social network size, significantly explained these increased psychiatric symptoms above and beyond other demographic factors. these findings together suggest that there will likely be an epidemic of mental illness in the near future, and preparing clinicians, caregivers and stakeholders to focus on alleviating loneliness would be one effective way to mitigate this impending public health crisis. the authors thank the respondents for donating their valuable time to complete this survey. this research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. note. all predictive models included predictive variables: age, sex (two dummy coded variables: female, and no response to the question of sex), frequency of domestic abuse/violence, level of concern about covid- , and ucla loneliness score. change statistics were relative to the reduced model, which contained only predictive variables (i.e., all variables except ucla loneliness score). physical health was not good: mean = . days (sd = . ). b) mental health was not good: mean = . days (sd = . ); c) usual activities were affected due to health problems: mean = . days (sd = . ); d) usual activities were affected due to pain: mean = . (sd = . ); and e) feeling worried, anxious, or tense: mean = . days (sd = . ). coronavirus disease (covid- ) in hk [www document multidisciplinary research priorities for the covid- pandemic: a call for action for mental health science. the lancet psychiatry the validity of the -item version of the prodromal questionnaire (pq- ) to screen for ultra high risk of developing psychosis in the general help-seeking population impact of ebola experiences and risk perceptions on mental health in sierra leone letter to the editor. loneliness : a signature mental health concern in the era of covid- pandemic and politics push hong kong's economy into record slump hong kong's unemployment rate rises to highest since prevalence, psychosocial correlates and service utilization of depressive and anxiety disorders in hong kong: the hong kong mental morbidity survey (hkmms) a community study of generalized anxiety disorder with vs. without health anxiety in hong kong the structure of negative emotional states: comparison of the depression anxiety stress scales (dass) with the beck depression and anxiety inventories manual for the depression anxiety & stress scales long-term psychiatric morbidities among sars survivors the impact of influenza on mental health in norway hong kong police arrest protesters for violating social distancing guidelines evaluating the effectiveness of social distancing interventions to delay or flatten the epidemic curve of coronavirus disease depression and post-traumatic stress during major social unrest in hong kong: a -year prospective cohort study hong kong police detain veteran democracy activists in raids hundreds of medical workers walk off in protest timeline: key dates in hong kong's anti-government protests [www document mental health outcomes among frontline and second-line health care workers during the coronavirus disease (covid- ) pandemic in italy ucla loneliness scale (version ): reliability,validity, and factor structure disability weights for the global burden of disease study covid- related loneliness and psychiatric symptoms among older adults: the buffering role of subjective age psychometric properties of a chinese version of the -item depression anxiety stress scales (dass ) covid- : a potential public health problem for homeless populations loneliness and social isolation as risk factors for coronary heart disease and stroke: systematic review and metaanalysis of longitudinal observational studies immediate psychological responses and associated factors during the initial stage of the coronavirus disease (covid- ) epidemic among the general population in china the impact of epidemic, war, prohibition and media on suicide: united states, - patients with mental health disorders in the covid- epidemic key: cord- -cxvnv dy authors: chastel, c. title: Émergence de virus nouveaux en asie : les changements climatiques sont-ils en cause ? date: - - journal: médecine et maladies infectieuses doi: . /j.medmal. . . sha: doc_id: cord_uid: cxvnv dy résumé l’afrique tropicale n’est pas la seule région du monde où des virus dangereux pour l’homme aient récemment émergé. l’asie, en particulier la chine et le sud-est asiatique, a également connu l’émergence de viroses humaines graves, telles que la dengue hémorragique (les philippines, ) ou plusieurs pandémies grippales, la grippe asiatique (n h ) en , la grippe de hong-kong (h n ) en , et la grippe russe (h n ) en . mais, c’est surtout au cours des dix dernières années que les émergences virales s’y sont multipliées avec l’apparition de la fièvre hémorragique à virus alkhurma en arabie saoudite ( ), de la grippe aviaire h n à hong-kong, en , de l’encéphalite à virus nipah en malaisie, en , et surtout du sras, en chine du sud en . les facteurs climatiques n’ont probablement joué qu’un rôle réduit dans le succès émergentiel de ces viroses, favorisé plutôt par des facteurs humains : le développement d’élevages industriels d’animaux de basse cour augmentant les risques d’épizooties, les habitudes alimentaires, les pressions économiques et démographiques, les négligences dans la surveillance épidémiologique et la déclaration des premiers cas. abstract tropical africa is not the only area where deadly viruses have recently emerged. in south-east asia severe epidemics of dengue hemorrhagic fever started in and flu pandemics have originated from china such as the asian flu (h n ) in , the hong-kong flu (h n ) in , and the russian flu (h n ) in . however, it is especially during the last ten years that very dangerous viruses for mankind have repeatedly developed in asia, with the occurrence of alkhurma hemorrhagic fever in saudi arabia ( ), avian flu (h n ) in hong-kong ( ), nipah virus encephalitis in malaysia ( ,) and, above all, the sars pandemic fever from southern china ( ). the evolution of these viral diseases was probably not directly affected by climate change. in fact, their emergential success may be better explained by the development of large industry poultry flocks increasing the risks of epizootics, dietary habits, economic and demographic constraints, and negligence in the surveillance and reporting of the first cases. au cours des cinquante dernières années, la plupart des virus « nouveaux » qui ont émergé provenaient d'afrique subsaharienne : fièvres hémorragiques africaines (marburg, lassa, ebola), sida, monkeypox, donnant l'impression que le continent africain était le réservoir de virus essentiel de la planète. mais d'autres virus nouveaux ont également émergé en asie, dont ceux de plusieurs pandémies grippales, de la dengue hémorragique et, plus récemment, le virus h n de la grippe aviaire, le virus nipah et le coronavirus du sras. quant aux virus du sida, ils continuent de progresser chaque jour en asie, notamment dans les pays les plus peuplés, l'inde, la chine et l'indonésie. le but de cette revue est non seulement de dresser le bilan des dernières émergences virales sur ce continent, mais aussi d'apprécier la part relative des facteurs humains et des facteurs environnementaux dans l'émergence et la réussite émergentielle [ ] de ces virus. pendant cette période, les techniques virologiques étaient encore sommaires. elles ont cependant permis l'isolement de certains des tous premiers virus reconnus pathogènes chez l'homme. ils sont répertoriés dans le tableau . ce sont tous des agents de zoonoses rurales entraînant chez l'homme une pathologie sévère et une mortalité pouvant dépasser le tiers des malades. parmi les survivants des encéphalites, les séquelles neurologiques sont fréquentes et graves. si leur nature virale a été assez rapidement prouvée pour l'encéphalite japonaise ( ) , pour l'encéphalite vernoestivale russe ( ) et pour la fièvre hémorragique de crimée ( ) , il a fallu attendre la fin des années pour que le virus de la fièvre hémorragique de corée mandchourie, maladie connue depuis les années sur les deux rives du fleuve amour, soit enfin isolé et caractérisé [ ] . il existe un bon vaccin contre l'encéphalite japonaise, le vaccin biken inactivé, produit sous licence par pasteur-mérieux. il convient pour la protection des personnes vivant ou se déplaçant en zone d'endémie (cf. géographie, tableau ), pour leur travail ou leurs loisirs. pour se protéger éventuellement de l'encéphalite vernoestivale russe, on dispose du vaccin inactivé fsme -immuno ® inject. il a été mis au point en autriche contre le virus de l'encéphalite européenne à tiques. cette dernière virose est transmise par la tique ixodes ricinus et son agent est un variant ouesteuropéen du virus russe. en france, ces vaccins sont accessibles dans les centres de vaccination contre la fièvre jaune. les progrès de la virologie ont permis de beaucoup améliorer nos connaissances sur les virus asiatiques. ainsi, la dengue hémorragique est apparue en aux philippines et elle a envahit ensuite tout le sud-est asiatique [ ] . plus qu'une émergence virale, c'était celle d'une nouvelle forme clinique, plus grave, parfois mortelle, de la « dengue classique » habituellement bénigne [ ] . contrairement aux fièvres hémorragiques précédemment décrites en asie (cf. . ), il s'agissait d'une maladie urbaine, frappant surtout de jeunes enfants autochtones et les vecteurs n'étaient pas des tiques mais des moustiques, aedes aegypti et aedes albopictus [ ] . plus tard, de jeunes adultes furent également atteints. pour expliquer son apparition, on a invoqué des facteurs essentiellement anthropiques. le développement monstrueux des grandes métropoles asiatiques, au cours des années - , a provoqué la prolifération des vecteurs, surtout d'a. aegypti, en même temps qu'une démographie galopante assurait un volant constamment renouvelé de jeunes enfants réceptifs. la circulation accélérée des quatre types sérologiques du virus de la dengue a provoqué une sensibilisation immunologique séquentielle de ces enfants, par ces flavivirus [ ] . il en est résulté une cascade d'événements immunopathologiques conduisant à la fragilité capillaire, aux hémorragies et au choc hypovolémique, mortel dans à % des cas. on ne dispose toujours d'aucun vaccin efficace contre la dengue qui est devenue, chez l'enfant, l'un des principaux problèmes de santé publique, en asie du sud-est. par ailleurs, deux autres fièvres hémorragiques virales, de distribution géographique plus restreinte et de moindre importance en santé publique ont été décrites. en , la fièvre de la forêt de kyasanur a été identifiée en inde, dans l'état de karnātaka, et la fièvre hémorragique d'omsk l'a été en , en sibérie occidentale. toutes deux sont transmises par des tiques et leurs agents étiologiques sont des flavivirus [ ] . le tableau clinique, fait d'hémorragies et de troubles neurologiques, est voisin dans les deux maladies et la mortalité ne dépasse pas %. mais le principal événement virologique fut l'apparition de pandémies grippales a : en , la « grippe asiatique » (h n ) et en , la « grippe de hong-kong » (h n ). elles ont permis de dégager une doctrine permettant d'expliquer l'apparition en chine du sud de virus grippaux entièrement nouveaux, par réassortiment génétique [ ] . l'existence dans de nombreuses régions rurales de ce pays, d'élevages de canards et de porcs, en étroite promiscuité avec la population, favorise le phénomène. le réservoir principal des virus grip- l'asie a subi, alors, comme le reste du monde, l'impact de plusieurs pandémies virales. ainsi, des enterovirus nouveaux ont, en - , envahi la planète, provoquant une pathologie jusque là inconnue : la conjonctivite hémorragique épidémique. cette virose oculaire extrêmement contagieuse provoque du larmoiement, des douleurs oculaires violentes, des hémorragies sous-conjonctivales et, éventuellement, une kératite. apparue en afrique occidentale ( ), elle a ensuite gagné rapidement le reste de l'afrique, l'europe et l'ensemble de l'asie, tout particulièrement l'inde, le japon et singapour ( ) . deux virus différents en étaient responsables : un variant du coxsackievirus a et l'enterovirus [ ] . l'inde fut à nouveau touché en . il n'existe ni traitement spécifique, ni vaccin. mais la pandémie la plus grave est, sans conteste, celle du sida, reconnu à partir de . les virus responsables ont été rapidement isolés et caractérisés, le vih en et le vih en . depuis, la maladie ne cesse de s'étendre dans le monde, l'asie constituant le deuxième foyer mondial, après celui de l'afrique subsaharienne. les pays les plus peuplés de la terre, l'inde (~ millions de personnes infectées) et la chine (~ infections) sont gravement atteints ainsi que tout le sud-est asiatique. fin , la région asie-pacifique comptait , millions de sujets infectés [ ] . l'asie est aussi une terre d'élection des hépatites virales. les virus a et b y sont largement répandus et c'est à taiwan que fut confirmé, de façon indiscutable, le lien existant entre l'hépatite b et le cancer primitif du foie [ ] . À la fin des années , les progrès de la virologie moléculaire ont montré que les virus c et e étaient également très présents en asie [ , ] . de plus, c'est en inde que la notion d'extrême gravité de l'hépatite e chez la femme enceinte (mortalité %) a été établie [ ] . enfin, en , on a observé la réémergence du virus grippal a (h n ), responsable de la « grippe russe ». le virus est apparu pratiquement simultanément en chine et en sibérie [ ] . ces émergences se sont produites à un rythme accéléré et certaines ont été particulièrement spectaculaires. elle est provoquée par un flavivirus nouveau qui a émergé en chez des bouchers d'abattoir, à djedda, en arabie saoudite. proche du virus de la forêt de kyasanur (kfd), alk provoque comme ce dernier une fièvre hémorragique sévère ou, plus rarement, une encéphalite [ ] . la source de la contamination est constituée par des moutons. actuellement, cas ont été identifiés à djedda et à la mecque, avec une mortalité de % [ ] . le génome du virus a été entièrement séquencé confirmant ses parentés génétiques avec le virus kfd [ ] . mais les virus kfd et alk occupent des niches écologiques totalement distinctes : une forêt humide dans le nord de l'inde, peuplée de singes et infestée de tiques pour kfd ; un environnement semi-désertique pour alk. outre le contact avec le sang de moutons infectés, la maladie pourrait être transmise par des tiques ou, encore, par la consommation de lait cru de chamelle. elle sévit en deux pics annuels : mai-juin et septembre-octobre [ ] . aucun vaccin n'est disponible actuellement. lorsqu'en , l'épidémie de grippe a (h n ), d'origine aviaire, éclata à hong-kong, elle eut immédiatement un fort retentissement médiatique. ce pouvait être le début, tant redouté, d'une nouvelle pandémie grippale qui, telle celle de - , pouvait faire des millions de morts [ , ] . les choses avaient débuté à bas bruit. en mai , un garçon de trois ans était mort d'une pneumonie grippale compliquée d'un syndrome de reye. la souche virale isolée à cette occasion était un virus grippal a non caractérisable par les méthodes courantes. c'était en réalité un virus grippal aviaire, de formule antigénique h n , jamais rencontré chez l'homme [ , ] . fin , nouveaux cas survinrent à hong-kong entraînant cinq autres décès, ce qui portait la mortalité totale à %, chiffre jamais atteint dans la grippe humaine. la plupart des malades avaient moins de ans, mais il y avait d'autres sujets nettement plus âgés. depuis le printemps , il y avait eu trois épizooties dans des élevages de poulets à hong-kong. elles étaient également dues au virus h n [ ] et les souches isolées de la volaille étaient identiques génétiquement à celles des cas humains. toutes les souches, humaines et animales, étaient d'un type purement aviaire. stupéfaction ! un virus grippal a aviaire avait franchi directement la « barrière d'espèce » humaine, sans réassortiment génétique préalable chez le porc. on extermina un million et demi de poulets fin et l'épidémie s'arrêta. il fut démontré que la transmission inter-humaine n'avait joué aucun rôle dans la propagation de l'épidémie, les malades s'étant tous probablement contaminés auprès de poulets infectés. le virus n'avait pas diffusé plus avant dans la population de hong-kong, justement du fait qu'il n'y avait pas eu de réassortiment avec les souches humaines. mais pourquoi le virus h n de hong-kong avait-il entraîné des infections d'une telle gravité chez l'homme ? l'autopsie de deux patients décédés a montré des altérations diffuses, un syndrome hémophagocytaire, de la nécrose des hépatocytes et des tubules rénaux, avec une forte déplétion lymphocytaire. pendant la maladie, il y avait eu une hyperproduction des cytokines inf-c et il- , et du récepteur soluble de il- [ ] . quant aux souches virales elles-mêmes, elles présentaient un site polybasique de clivage de l'hémagglutinine, caractéristique des souches aviaires très virulentes [ ] . [ ] . ils avaient voyagé dans la province de fujian, dans le sud-est de la chine, les souches virales isolées de ces derniers malades étaient de type aviaire, mais différaient génétiquement de celles isolées en [ ] . enfin en janvier , h n a réémergé chez l'homme au vietnam, au cambodge, au laos et en thaïlande, tandis que des élevages de poulets et de canards étaient infectés dans ces mêmes pays et en corée du sud, en chine, au pakistan et au japon. et le massacre de la volaille a repris de plus belle... un faucon pèlerin (falco peregrinus) a même été trouvé mort à hong-kong, infecté par h n . on redoute toujours, à l'occasion de ces réémergences multiples, un réassortiment génétique désastreux pour notre espèce. d'autant plus que la diversité génétique des souches de h n circulant dans la région semble avoir beaucoup augmenté depuis . c'est peut-être la conséquence des vaccinations réalisées dans les élevages de poulets, en chine, avec un vaccin insuffisamment immunogène. il aurait pu masquer la symptomatologie chez les poulets infectés, sans empêcher que ceux-ci diffusent l'infection autour d'eux (newscientist, février ). pour le moment, il n'existe aucun vaccin à usage humain contre h n . ce virus a émergé brusquement en malaisie, en , provoquant une grave épidémie d'encéphalite chez des éleveurs de porcs [ ] . les États de negri sembilan, pérak et sélangor ont été les plus touchés : cas humains ont été enregistrés entre septembre et avril , entraînant la mort de malades, soit , % [ ] . c'était le prolongement humain d'une épizootie porcine qui avait tué % des porcs atteints. on crut d'abord avoir affaire à une poussée d'encéphalite japonaise, mais les données épidémiologiques n'étaient pas en faveur d'une telle hypothèse, même s'il y eut probablement des infections mixtes. en fait, les malades étaient des hommes adultes, souvent vaccinés contre l'encéphalite japonaise et ayant eu des contacts professionnels avec des porcs malades [ , ] . en mars , un autre foyer épidémique apparut à singapour, touchant travailleurs des abattoirs, infectés par des porcs importés de malaisie ; il n'y eut heureusement qu'un seul décès [ , ] . l'étude anatomopathologique de cas humains a révélé des lésions diffuses de capillarite nécrosante, notamment au niveau de l'encéphale [ , , ] . le virus nipah, grâce à sa protéine v, peut inhiber l'action antivirale des inf-a et c, in vitro [ ] . pour la seule fédération de malaisie, plus d'un million de porcs furent euthanasiés [ ] , ce qui a représenté de lourdes pertes économiques pour ce pays, fort exportateur. deux militaires sur les engagés dans ce programme contractèrent une encéphalite tandis que six autres étaient infectés de façon inapparente, malgré le port de masques, de gants, de lunettes et de bottes [ ] . le virus nipah est apparenté au virus hendra isolé précédemment en australie où il a tué des chevaux et des personnes en contact directe avec ces derniers [ ] . ces virus appartiennent à un genre nouveau, henipavirus, de la sousfamille des paramyxovirinae. comme le virus hendra est associé à des chauves-souris on a, naturellement, recherché des traces d'activité du virus nipah chez les chiroptères du sud-est asiatique. effectivement, des anticorps neutralisant ce virus ont été décelés chez cinq espèces de chauves-souris de malaisie, tant frugivores (surtout des roussettes) qu'insectivores [ ] , et chez des roussettes (pteropus lylei) proposées à la consommation dans des restaurants, au cambodge [ ] . finalement, le virus nipah a été isolé des urines de la roussette pteropus hypomelanus, en malaisie [ ] . ces chiroptères sont donc, très vraisemblablement les réservoirs du virus nipah dans la nature. depuis l'extermination des porcs infectés, on a plus signalé de cas d'encéphalite à virus nipah, mais il convient de rester vigilant car les roussettes et les porcs sont très nombreux dans tout le sud-est asiatique. heureusement, la ribavirine semble pouvoir réduire la mortalité chez l'homme [ ] et un vaccin recombinant pasteur-mérieux est à l'étude [ ] . c'est la première pandémie du xxi e siècle, apparue en chine méridionale, à la fin de . elle a démontré à la fois la fragilité de nos systèmes de santé et l'intérêt évident d'une coopération scientifique internationale. le mars , l'oms a lancé une alerte mondiale concernant l'apparition à hong-kong, d'une épidémie inquiétante de « pneumonie atypique transmissible », baptisée sras peu après. cette maladie atteignait plus volontiers le personnel des services d'urgence et des sujets relativement âgés, mais pas exclusivement. l'évolution clinique était progressive et la mortalité se situait entre et %. ce n'était pas non plus de la grippe. l'épidémie a ensuite gagné hanoi, singapour, beijing, bangkok, toronto et vancouver, se manifestant dans une trentaine de pays. quelques cas furent rapportés en europe, dont sept en france, heureusement non mortels. le personnel des soins intensifs et les proches parents, ceux qui étaient en contact très étroit avec des malades, étaient les plus atteints. l'incubation durait de heures à sept jours. en fait, dès la mi-novembre , cette épidémie s'était manifestée en chine du sud, dans la province de guangdong, où elle avait tué plus de personnes, sans que les autorités chinoises informent la communauté internationale. bien plus, elles retardèrent l'accès de la région aux experts de l'oms. le virus responsable fut rapidement isolé et caractérisé au point de vue biologique et génétique [ ] . c'était un coronavirus entièrement nouveau, le sars-cov dédié au docteur carlo urbani, le représentant de l'oms à hanoï, mort dans les premiers du fait de son dévouement. ce virus différait complètement des coronavirus que l'on connaissait déjà chez l'homme et les animaux domestiques ou de compagnie [ ] . la coopération de laboratoires nationaux de virologie, coordonnés par l'o.m.s., a permis ce résultat spectaculaire qui aurait pu être encore plus rapide si les autorités politiques et sanitaires chinoises avaient preuve d'un peu plus de responsabilité [ ] . ce succès ouvrait la voie à la mise au point de tests diagnostiques fiables, de vaccins, d'antiviraux et à la compréhension de la pathogénie du sras. contrairement à ce qui a pu être dit, les coronavirus ont une certaine résistance dans le milieu extérieur, en particuliers ceux qui infectent les porcs [ ] . cela pourrait expliquer la facilité avec laquelle le sras a diffusé, à partir d'un seul cas-index, dans le « amoy gardens apartment block » de hong-kong, infectant résidents. chez les malades (comme chez les animaux), le virus est présent non seulement dans les sécrétions nasales et pharyngées, mais également dans les selles ( % par rt-pcr), et % des patients sont diarrhéiques [ ] . d'ailleurs, comment expliquer autrement que par une certaine résistance des virus, les infections de laboratoire rapportées fin à singapour et à taiwan. on a aussi suspecté les rats domestiques d'avoir propagé le sras dans le « amoy gardens » [ ] . reste l'épineuse, mais essentielle question de l'origine du virus. l'hypothèse la plus vraisemblable est celle d'un réservoir de virus animal. l'attention des virologistes de hong-kong s'est rapidement portée sur la faune sauvage ou semisauvage, proposée à la vente sur les marchés du sud de la chine, afin de satisfaire les goûts culinaires des gastronomes locaux. on y trouve des pangolins, civettes, blaireaux, chauves-souris, singes, serpents, etc., dans une extraordinaire promiscuité avec l'homme. sur le marché de shenzhen, dans la province de guangdong qui fut l'épicentre de l'épidémie de , ils ont isolé [ ] un coronavirus très proche de celui du sras chez plusieurs civettes de l'himalaya (paguna larvata) et chez un chien viverrin (nyctereutes trocyonoides). au même endroit, un blaireau chinois (melogale moschata) fut trouvé porteur d'anticorps spécifiques. les souches virales isolées de ces animaux diffèrent de celles de l'homme atteint de sras par la présence, dans leur génome, de nucléotides supplémentaires [ ] . ce n'est probablement pas la consommation de leur viande qui assure la contamination humaine, car ces virus ne résistent pas à la cuisson. ce serait plutôt le stockage en cage, la vente, le dépeçage et la préparation en cuisine qui permettrait au virus de franchir la « barrière » de notre espèce. alors que de nouveaux cas de sras sont apparus en chine, début , de plus en plus d'arguments virologiques et épidémiologiques désignent la civette de l'himalaya, sinon comme le réservoir primaire du virus, du moins comme le vecteur de l'infection, avec peut-être également les rats [ ] et les chats domestiques, ces derniers ayant été trouvés infectés dans le « amoy gardens ». ces conclusions récentes ont valu à plus de civettes d'élevage un pogrome très médiatisé. le sras n'a certainement pas fini de faire parler de lui. des vaccins sont à l'étude. la ribavirine semble avoir une certaine activité sur le virus. . face à l'émergence de nouvelles zoonoses virales, la notion de « barrière d'espèce » peut même s'avérer dangereuse, en conduisant les autorités sanitaires à sous-estimer les risques pour l'homme d'une maladie animale quelle qu'en soit la nature. on a encore en tête, l'émergence chez l'homme, en , du nouveau variant de la maladie de creutzfelt-jakob, dont une soit disant barrière devait nous protéger. ensuite, il est de plus en plus évident que la chine et le sud-est asiatique représentent une formidable machine à faire émerger des virus dangereux pour notre espèce. par ailleurs, si l'on cherche à comprendre pourquoi les émergences virales récentes en asie ont eu des succès émer-gentiels variables, il faut faire appel à la biologie moléculaire des virus à arn. en , à hong-kong, l'épidémie de grippe h n s'est arrêtée après que les poulets responsables aient été tous exterminés. il n'y a pas eu d'extension interhumaine de la maladie car h n n'a pas eu le temps ou l'opportunité, de se réassortir avec des souches du virus grippal a humaines. toutefois, il faut rester vigilant. les réémergences récentes de h n au vietnam, en corée du sud, au cambodge, en chine, au japon et en indonésie risquent d'apporter à ce virus de nouvelles occasions de réassortiment génétique, d'où l'inquiétude justifiée de l'oms. le coronavirus du sras apparaît, à priori, le plus dangereux. il a bien réussi sa première émergence [ ] , infectant plus de personnes, dans une trentaine de pays différents. il se transmet très bien d'un malade à son entourage immédiat, médical ou familial. si on applique au sras le concept du ro (« basis reproductive number »), c'est à dire la capacité moyenne à se transmettre, d'un individu infecté à un ou plusieurs sujets réceptifs d'une population non immune [ , ] , le sras bénéficie d'un ro nettement supérieur à un, du moins au cours de certaines étapes de sa propagation planétaire. par comparaison, les infections à h n ou nipah sont caractérisés par un ro voisin de zéro. enfin, si l'on cherche à estimer le poids des facteurs humains et des facteurs environnementaux tels que le réchauffement planétaire, dans le succès émergentiel de ces virus, il est clair que le principal responsable est l'homme lui-même. c'est lui qui a installé des élevages industriels, parfois monstrueux, de volailles (chine : , milliard de poulets pour la seule province de guangdong), de porcs (malaisie) ou de civettes (chine du sud), constituant autant de milieux artificiels favorables à l'éclosion d'épizooties. la mauvaise foi des autorités chinoises face aux problèmes du sras ou de h n , relève de la nature humaine. en revanche, les changements climatiques, le phénomène el niño [ ] , dont la réalité ne peut être niée, représentent pour les virus examinés ici, peu de chose face aux comportements humains et aux habitudes culturelles, notamment alimentaires. les maladies virales, susceptibles d'être influencées par le réchauffement planétaire sont des infections à transmission vectorielle, faisant intervenir des tiques, des moustiques ou des rongeurs [ ] . ce n'est le cas ni pour la grippe aviaire h n , ni pour l'encéphalite à virus nipah, ni pour le sras. les infections virales dont l'épidémiologie pourrait être modifiée par des changements climatiques, dans le sudest asiatique, sont plutôt l'encéphalite japonaise et la dengue, mais pour le moment rien n'a été publié dans ce sens. Émergences virales chez l'homme et réussite émergentielle isolation of the etiologic agent of korean hemorrhagic fever mosquito-borne hemorrhagic fevers of south and south-east asia réflexions sur deux viroses d'actualité: la fièvre jaune et la dengue pathogenesis of dengue : challenges to molecular biology arbovirus transmis par des tiques et pathogènes pour l'homme ou pour les animaux domestiques pandemic influenza: a zoonosis les virus responsables de conjonctivites hémorragiques le point sur l'épidémie de sida hepatocellular carcinoma and hepatitis b virus: a prospective study of men in taiwan les sous-types génomiques du virus de l'hépatite c : épidémiologie, diagnostic et conséquences cliniques répartition géographique des génotypes du virus de l'hépatite e incidence and severity of viral hepatitis in pregnancy the next influenza pandemic: lessons from hong-kong isolation of a flavivirus related to the tick-borne encephalitis complex from cases in saudi arabia le virus alkhurma (famille des flaviviridae, genre flavivirus) : un pathogène émergent responsable de fièvres hémorragiques au moyen-orient a pandemic warning grippe aviaire a (h n ) : cul-de-sac épidémiologique ou prémices d'une nouvelle pandémie ? human influenza a h n virus related to a highly pathogenic avian influenza virus characterization of an avian influenza a (h n ) virus isolated from a child with a fatal respiratory illness characterization of avian h n influenza viruses from poultry in hong-kong pathology of fatal human infection associated with avian influenza a h n virus induction of proinflammatory cytokins in human macrophages by influenza a (h n ) viruses: a mechanism for unusual severity of human disease? lethal h n influenza viruses escape host antiviral cytokin responses fatal encephalitis due to nipah virus among pig-farmers in malaysia nipah virus: a recently emergent deadly paramyxovirus identification d'un nouvel agent d'encéphalites en malaisie : le virus nipah, proche du virus hendra outbreak of nipah-virus infection among abattoir workers in singapore nipah virus infection; pathology and pathogenesis of an emerging paramyxoviral zoonosis nipah virus v protein evades alpha and gamma interferon by preventing stat and stat activation and nuclear accumulation nipah virus infection among military personnel involved in pig culling during an outbreak of encephalitis in malaysia a morbillivirus that caused fatal disease in horses and humans nipah virus infection in bats (order chiroptera) in peninsular malaysia antibodies to nipah-like virus in bats isolation of nipah virus from malaysian island flying foxes treatment of acute nipah encephalitis with ribavirin nipah virus: vaccination and passive protection studies in a hamster model characterization of a novel coronavirus associated vith severe acute respiratory syndrome coronavirus : une émergence réussie china's missed chance enzymatic and acidic sensivity profiles of selected virulent and attenuated transmissible gastroenteritis viruses of swine clinical progression and viral load in a community outbreak of coronavirusassociated sars pneumonia: a prospective study possible role of an animal vector in the sars outbreak at amoy gardens isolation and characterization of viruses related to the coronavirus from animals in southern china sars virus infection of cats and ferrets epidemics-in-waiting the role of evolution in the emergence of infections diseases el niño and health incidence des changements climatiques planétaires sur les arboviroses transmises à l'homme par des moustiques et des tiques key: cord- -tsm zoe authors: slaughter, laura; keselman, alla; kushniruk, andre; patel, vimla l. title: a framework for capturing the interactions between laypersons’ understanding of disease, information gathering behaviors, and actions taken during an epidemic date: - - journal: j biomed inform doi: . /j.jbi. . . sha: doc_id: cord_uid: tsm zoe this paper provides a description of a methodological framework designed to capture the inter-relationships between the lay publics’ understanding of health-related processes, information gathering behaviors, and actions taken during an outbreak. we developed and refined our methods during a study involving eight participants living in severe acute respiratory syndrome (sars)-affected areas (hong kong, taiwan, and toronto). the framework is an adaptation of narrative analysis, a qualitative method that is used to investigate a phenomenon through interpretation of the stories people tell about their experiences. from our work, several hypotheses emerged that will contribute to future research. for example, our findings showed that many decisions in an epidemic are carefully considered and involve use of significant information gathering. having a good model of lay actions based on information received and beliefs held will contribute to the development of more effective information support systems in the event of a future epidemic. there is a great deal of current interest in preparing for outbreaks of infectious disease. both national and international efforts are aimed at developing strategies for rapid containment in the event of an outbreak [ ] . government officials seek to contain an infectious disease through the cooperative efforts of the public by providing information either directly (pamphlets, web sites, posters, etc.) or through mass media news. the public also finds information concerning an outbreak from television programs and newspaper articles as well as from various ''non-official'' sources (e.g., socially through word-of-mouth). recent initiatives [ ] show support for research that concerns tailoring public health messages during an outbreak disaster to the lay public ''with care so that information reported is easy to understand, is appropriate and is relevant. '' in this paper, we propose a qualitative methodological framework that characterizes human behavior during epidemics. this methodological framework, based on narrative analysis, is a tool for learning about how laypersons use information to build representations of an epidemic situation and how the results of this process influence their decisions to act. two factors, social influences and emotional triggers, are considered as mediators of actions and are therefore also of concern to this work. the methods we use allow insights into actions taken that are interpreted within the partici-pantÕs situation (i.e., from the participantÕs own viewpoint). this type of work is essential for tailoring health messages that are useable by people during an epidemic and effective at changing risky behaviors. we outline our methods using illustrative examples from data collected during the sars epidemic of [ ] . section discusses theoretical background with a specific focus on lay information gathering, lay understanding of disease, and lay health decision actions in a naturalistic setting. in section , we outline the basis for our methodological approach and describe our techniques used for capturing the interactions between the informational influences on lay actions. the data analysis techniques are also presented in section . an illustrative example using data collected during the sars outbreak of is discussed in section . our methodology was refined through application of the framework to the analysis of these data. in section , we summarize the lessons learned and provide direction for future research. the authors of this paper argue that a qualitative approach is necessary in order to obtain a macroscopic view of lay reactions to an epidemic crisis and to map out variables for large-scale studies. the related work we cite in support of this study does not fit neatly into the boundaries of a single field. health-related information seeking theories [ ] and guidelines for constructing health messages for the public [ ] have not been explicitly connected to lay explanations of illness and their behaviors during an epidemic. the main purpose of presenting our methodology is to demonstrate how the data analysis techniques can characterize the relationships between lay information gathering, understanding of information received, and actions taken. we briefly review literature related to information seeking, perceiving information needs [ , ] , and emotional effects that play into lay perceptions of information [ ] . we also point to cognitive theories related to lay comprehension and reasoning about illness [ , ] in addition to theories of naturalistic decision-making [ , ] . we have defined ''information gathering'' in the broad sense, to include both passive reception of informational messages in the environment and active searching [ ] . general models of active information seeking [ , ] describe the process of how a person seeks information, from an emerging awareness of a ''gap'' in current knowledge to communication of this information need as a query that will locate the missing information. within the domain of health information seeking, the models that relate to a gap in knowledge alone were found to be insufficient because they focus exclusively on rational processes. they cannot explain information-seeking behavior when patients do not seek medical information even though they are aware of gaps in their knowledge [ ] . for health-related information seeking, theories of stress and coping have been integrated with two cognitive states that have been proposed as central to understanding an individualÕs response to an adverse health-related situation: orientation towards a threat (referred to as monitoring) and turning attention away from the threat (referred to as blunting) [ ] [ ] [ ] . the first studies that incorporated stress/coping theories with monitoring/blunting divided people according to personality types, as measured by the miller behavioral style scale (mbss). van zuuren and wolfs [ ] studied undergraduate students using the miller scale to assess whether a person is a monitor or a blunter. they found a direct association between problem-focused coping and monitoring. this study also showed that monitoring is related to unpredictability. they concluded that monitoring was positively related to the perceived degree of threat in a situation, that is, the higher the perceived threat the more information would be sought. using van zuuren and wolfÕs techniques of dividing a sample based on the mbss, researchers such as baker [ ] studied the information preferences of health consumers (in bakerÕs study using women with multiple sclerosis). her results indicated, ''monitors were more interested in information about ms than were blunters and further, that their interest occurred earlier in the disease than did the interest of blunters.'' in recent articles, the notion of personality type influencing information seeking has been challenged. rees and bath [ ] studied information seeking behaviors of women with breast cancer with results indicating that individuals may fluctuate between seeking and avoiding information, with the process being dependent on situational variables, such as how controllable the threat is perceived to be. due to the results given above, our data analysis attends to participantÕs discussions about risk perceptions that are connected with information seeking acts. our expectation is that narrative data will reveal how information-seeking behaviors are affected by emotional stress and fear of infection (high risk perception). this idea is further supported by the literature from the field of public health that examines how heath information disseminated during a crisis is interpreted by laypersons [ , ] . after information is gathered, it must be understood in order to be useful. gaining an understanding, or mental representation, occurs through the process of comprehension [ ] . research on lay mental representations has shown that knowledge about disease consists of a combination of representations constructed from both informal social channels (i.e., traditional remedies learned from extended family) and formal instruction of scientific knowledge [ ] . these two types of knowledge may be partly overlapping and contradictory when they deal with different aspects of the same disease. in cases where more than one model is used, a person tries to satisfy the requirements of each model even though this results in some redundant activity. research by keselman et al. [ ] concerning adoles-centsÕ reasoning about hiv provides an example of contradictory and overlapping models. they found that middle and high school students often relied on practical knowledge of disease, rather than on known facts about hiv. for example, one student acknowledged known facts about hiv, such as the fact that it is incurable. however, other explanations of the disease process later came into play while reasoning through a scenario about hiv. the scenario asked the student to discuss whether it was possible to expel hiv from the body. the same student who acknowledged the fact that hiv was incurable also believed that by drinking and exercising heavily it would be possible to expel hiv from the body. this student stated, ''cause people can stop it like that. by exercising, like they said. like that lady, like i told you, she exercised her way out of cancer, so i think this is true, you can exercise your way out of hiv probably.'' informally learned remedies and cultural beliefs sometimes play a major role in determining lay interpretations of epidemic events. for instance, raza et al. [ ] examined lay understanding of the plague with persons belonging to the economically weaker sections of society in delhi and gurgaon india. in identifying the factors that influence the public understanding of science, they found significant amount of lay understanding based on ''extra-scientific belief systems'' (e.g., sins committed by people contributed to the outbreak), which were prevalent in the context of the plague epidemic. other studies have also looked specifically at the use of mental representations in relationship to decision-making. patel and colleagues [ ] showed how physicians with different levels of expertise construct dissimilar problem representations on the basis of the same source information, which leads them to differing diagnostic decisions. as another example, sivaramakrishnan and patel [ ] showed how understanding of pediatric illnesses influenced mothersÕ choice of treatment for their children. their study showed how mothers interpreted concepts related to biomedical theories of nutritional disorders. they found that traditional knowledge and beliefs played an important role in interpretation and reasoning, which lead to decisions that were influenced by nonscientific traditional ideas. our work focuses on comprehended representations that are constructed by laypersons based on the information received during the epidemic (e.g., mass media, conversations with friends). we are interested in how these resulting representations lead to actions. the naturalistic approach to decision-making investigates decisions made in constantly changing environments, with ill-structured problems and multiple players [ ] . these studies are conducted in real-life settings and investigate high-stakes decisions by looking at how people assess the situations they face, determine the problems they need to address, then plan, make choices, and take actions. this approach is related to our work since the actions taken by laypersons during an outbreak occur in an uncertain environment, with information changing over time, and with a highly personal threat. blandford and wong [ ] has taken the key features of naturalistic decisions and combined them to form his integrated decision model. he used this framework for investigating decision processes and strategies of ambulance dispatchers. the ambulance dispatcher study used retrospective narrative data to build a model of decision-making in a dynamic, high-stakes environment. in summary, this model is based on the decision features: ( ) situation assessment is important to decision making, ( ) feature matching and story building are key to situation assessment because of missing information and uncertainty about available information, ( ) piecing together the situational information is difficult because it arrives over a period of time and not in the most optimal manner, and ( ) analytically generating and simultaneously evaluating all possible actions does not occur in dynamic environments. instead decision makers seek to identify the actions that best match the patterns of activities recognized in the situation assessment, one option at a time. although the framework provided by this study was formed from investigations of medical per-sonnelÕs decisions, we believe that these observations will apply to our work and can be extended to layper-sonsÕ actions in a high stress health-related situation. in our study, the infectious disease we are concerned with is severe acute respiratory syndrome (sars), which is a highly contagious respiratory illness that emerged in the guangdong province of china during the winter of . the sars virus caused widespread public concern as it spread with exceptional speed to countries in asia, the americas, and europe. there were confirmed cases in march when the world health organization (who) officially announced the global threat of a sars epidemic. in one month, the number of cases jumped to with more than deaths. the sars epidemic had been halted by july , with a total of cases reported to who and deaths [ ] . the countries affected by the outbreak of sars launched mass media campaigns to educate the public. information about what actions to take, the symptoms of sars, and other essential news changed on a daily basis as scientists and doctors treating sars cases reported new findings. the publicÕs ability to understand and react to the information they obtained played a key role in stopping the spread of sars. the multifaceted control efforts including quarantine, tracing the contacts of sars patients, travel restrictions, and fever checks were essential to containment. all of these required that the public understand the sars-related information being conveyed and take actions to help protect themselves and others from spreading the disease. the sars epidemic provided a useful test case for our work and provided us with an opportunity to refine our narrative analysis-based methodology. there have been various methodologies used to study human behavior during epidemics and these offer different perspectives on lay response patterns. one approach is to study historical accounts [ ] [ ] [ ] . these are usually told from a single personÕs perspective on a groupÕs response. while conclusions drawn from these types of texts might lend themselves to a global picture of an epidemic situation, there are potential drawbacks to using these as a basis for our present day outbreak preparation efforts. for instance, the occurrence describes peo-pleÕs reactions during a different time period (not living in our current culture) and these texts might be biased towards the view of the author. another method of understanding lay reaction is through questionnaires/ surveys following a real-life episode [ ] or a simulation of an outbreak [ , ] . these questionnaires use pre-defined categories leading to large amounts of data on select variables of interest (e.g., whether or not people believe they would follow quarantine restrictions). the questionnaires impose a pre-determined structure onto the respondent and force the respondent to reply using the investigatorsÕ categories. in our work, participants discuss events occurring during a recent outbreak that directly affected their life (occurring in close proximity to their home). a ''storybased'' interview allows data analysis of what information was obtained through the environment (e.g., media, web searches, rumors, and conversations with friends), reactions to the information, and the actions taken in the context of the participant who experienced it. these personal accounts, or narratives, of first-hand experience are a valuable source of data that can offer insight into a situation as it unfolded over time. by studying a sequence of events told as a retrospective narrative, an investigator can see how individuals temporally and causally link events (episodes) together. this approach falls under the qualitative paradigm and is referred to as narrative analysis [ ] ; these methods have to do with the ''systematic interpretation of interpretation [ ] .'' narrative analysis is commonly used as a methodological tool in health psychology [ , ] and anthropology [ ] . stories people tell are based on their mental representations of illness or ''learned internalized patterns of thought-feeling that mediate both the interpretation of ongoing experience and the reconstruction of memories'' [ ] . narratives tell us something about how individuals understand events and construct meaning out of a situation. illnesses are often explained by reconstructing events in a cohesive story-like manner. for example, garro [ ] discusses how people talk about illness; they link their experiences from the past with present concerns and future possibilities. narrative analysis is best used for exploratory purposes, for helping a researcher understand how individuals view a particular situation, and also for illustrating (but not by itself validating) theory. it is based on inductive techniques, rather than deductive hypothesis testing. this means that the researcher outlines top-level questions, which will be elaborated on and altered as the process of data analysis proceeds. personal narratives tell us a great deal about social, cultural, and other beliefs that cannot be accounted for at the onset of the study. the questions used to begin a study are broadly stated and are used, along with background literature, to focus on the initial set of boundaries delimiting the research. we ask how and why (i.e., meaning we are asking for a description) rather than what (e.g., a list of factors) questions. the main idea is to characterize the inter-relationships between laypersonÕs information needs/gathering, comprehension of information received, and actions during an epidemic. participants in qualitative studies, narrative analysis included, are usually selected based on specifically defined criteria. in a study of lay reactions to an epidemic, it is therefore important to select participants who lived in close proximity to the outbreak. the participants should tell their stories to the researcher as close in time to the actual experience as possible (perhaps while the outbreak is still ongoing). depending on whether the researcher wants to do comparative analyses, participants might be selected by and grouped according to various dimensions such as age, socio-eco-nomic status, ethnicity, and/or geographical location. the number of participants selected is dependent on the number of comparisons to be made, and whether the researchersÕ goals are to continue capturing narratives until the majority of the data contain overlapping experiences (almost all of the possible reactions to the epidemic have been uncovered). narrative data are usually collected through the use of an interview. we advocate a semi-structured interview [ ] that lists a pre-determined set of ''loosely ordered'' questions or issues that are to be explored. the guide serves as a checklist during the interview so that the same types of information will be obtained from all participants. the advantage of this approach is that it is both systematic and comprehensive in delimiting the issues to be taken up in the interview. the interviews can remain conversational while at the same time allow the researcher to collect specific data. in many qualitative studies an interview is usually. in many qualitative studies an interview is usually organized around question-answer exchanges, but narrative studies require the use of free openended ''tell me'' questions as the most effective way to elicit a story-like response. it is important to avoid the use of closed, ''yes/no'' questions in order to facilitate narrative, rich descriptions. decisions about how to transcribe data and conventions used for analysis are driven by current theory, the research questions of interest, as well as the personal philosophy of the researcher. our analytic interpretations of epidemic narratives progress through three stages: ( ) thematic coding of the factors emerging from the stories told concerning the epidemic, ( ) organization of various aspects of the story according to chronological order, and ( ) ''influence diagrams'' of factors influencing actions taken. thematic coding [ ] is a type of content analysis and this technique is based on grounded theory (using a bottom-up procedure to identify categories present in the text). narratives may also be coded according to categories deemed theoretically important by the researcher. initially, a set of categories can be derived in conjunction with the semi-structured interviews based on theory from related literature (an initial top-down approach to coding), and this list of categories can grow as the rich descriptive data (a bottom-up procedure) is analyzed. one of the purposes of the ''thematic coding'' stage is to support the subsequent analyses. the categories are used to help untangle the interrelationships between information, understanding, emotions, social factors, and actions taken and systematically map our observations. in addition, an accuracy check can be done to determine whether participants are correct about their understanding of the disease. actions participants stated they have taken can be compared with guidelines from official sources (e.g., cdc). when participants speak freely in telling stories about the events happening this results in quite a bit of ''jumping around'' in time. people do not always begin their stories with the first event that occurred. researchers frequently find it helpful to organize the narrative according to temporal sequence (see labovÕs work [ ] ). for this work, classifying the temporal order of events is a necessary process leading to proper analysis of informational and comprehension-of-situation influences on actions taken. data are temporally coded in order to consolidate events participants expressed as occurring at the same time period (according to the participantÕs perception of events). to illustrate, ''time '' is assigned to link together the segments - shown below and the same code ''time '' is assigned to segments of text lines - found later in the interview. and i spoke to my girlfriend and she said that she was going to leave hong kong and i was really shocked because she was the one that was like myself, just kind of sticking around and saying oh itÕs not a big deal and weÕll manage and uh she um felt that she just got into a panic herself. and what happened around that time at the end of march that there was a rumor that a teenager actually started on the internet, he put it on he like, he said that the airport had been closed and that people couldnÕt get in or out of hong kong and they later deemed of course it was a hoax. but at the time my girlfriend heard this, she didnÕt know, she panicked and she was leaving. . . . later in the interview . . . i did a bit more internet grocery shopping because i did not want to go to the grocery stores. usually, it was really strange because right around, right. . . a week or so before i left i would go to the market. it was actually; it was right around the time that that rumor came out that the hong kong airport had shut down. the store was so packed it was unbelievable. i thought it was a holiday, and i even asked a friend. i said, what is going on with the market? the construction of causal-link maps, sometimes referred to as ''influence diagrams,'' is used for modeling interactions between events [ ] . these types of diagrams formalize laypersonsÕ explanations into connected logical structures that can be examined as an overview of all the events occurring for a subset of time during an epidemic. this process maps the influences on actions taken for each time period identified (following chronological organization of the data described in section . . ). figs. - are each influence diagrams. an example of how we created these diagrams is given using data from the taiwanese participant (see fig. ). we first identify the associative ''participantstated'' relationships between coded themes. in these data segments, we can see that officials are promoting (successfully) washing hands and we can also see that family pressures have an influence on hand washing behaviors. thus, ''informational: officials <promotes> action: washing hands'' and ''social: family pressure <leads_one_to>action: washing hands.'' the categories of interaction labels (e.g., <promotes>) must be standardized for consistency. this process facilitates asking research questions across conditions (e.g., comparisons by socio-economic status) for numerous participants. eventually, the objective is to be able to make generalizations about the interactions between factors/events that influence layperson reactions during an epidemic. what are laypersonsÕ decisions based on? how does social pressure affect decisions? what motivates active searching of information? the evaluation of the validity (or trustworthiness) of a narrative analysis is a critical issue that does not have an easy solution. one way to test whether the results are valid is related to persuasiveness. an analysis can be said to be persuasive when ''the claims made are supported by evidence from the data and the interpretation is considered reasonable and convincing in light of alternative possible interpretations'' [ ] . another way of checking validity is to conduct what is called a ''member check'' [ ] . during a member check, participants in the study are given copies of the research report and asked to appraise the analysis conducted by the researcher, interpretations made, and conclusions drawn. these two measures of validity assess whether the interpreta- tions of the data reflect the views held by the participant; there is no way to compare the results obtained with an objective truth. however, a community of scientists validates knowledge as they share results obtained across multiple studies. as the sars epidemic unfolded, we were in the process of exploring methodologies that would focus on the interactions among the information requirements of laypeople concerning an outbreak of infectious disease, their understanding of that disease, and their actions taken during an outbreak (or during a simulated outbreak). the sars epidemic was used as a test study to refine the narrative analysis-based methodology. in the following sections, we show how these methods were applied and what we learned in the process. our specific research objective is to characterize lay-personsÕ reactions during an epidemic. specifically, we ask why participants take certain actions (or recommended actions stating what should be done) and how their actions are linked to ( ) their understanding of epidemic/sars infection, ( ) the influential informational events (including information gained from a social situation), and ( ) other factors such as feelings that come into play. other research questions can be answered using the data that report on what happened during the sars outbreak. for example, the interview texts also result in a list of information needs expressed by the lay public concerning an outbreak as well as a general list of actions taken for sars prevention. we interviewed eight residents from three sars outbreak regions. two of them were living in asia ( from hong kong and from taiwan) and six were from toronto, canada. participants recalled events taking place from the time when news began about the ''mysterious'' illness until the time of the interview, a time span of approximately - days. none of the participants had a medical background or a degree in biology, or related fields. all of the participants except for the taiwanese male were native english speakers. the interviews with the residents from asia took place in the late spring of . these interviews were conducted in the united states by the first author. the hong kong resident was an american caucasian female who had been living in hong kong for the past four years. she decided in late march to return to the united states temporarily because of the sars outbreak. she was , married and had a one-year-old daughter at the time of the interview. she was interviewed in her home in washington, dc. the other resident of asia was a taiwanese male, aged , of chinese descent, who was living in taipei, taiwan for the entire duration of the epidemic. the interview took place in new york city while he was vacationing. both participants had an undergraduate degree from a university in the united states. the interviews with the toronto residents took place during the early summer of . these interviews took place in toronto and were conducted by a research assistant from the information technology division, department of mathematics and statistics, york university, toronto. toronto resident was a -year-old male, resident was female (no age recorded), resident was a -year-old female, resident was a -yearold female, resident was a -year-old male, and resident was a -year-old male. toronto residents all had bachelorÕs degrees, and residents and also had a masterÕs degree. the complete semi-structured interview is presented in appendix a. the procedure for using this interview guide is to allow for flexibility when probing the respondent. when interviewing, we stressed the importance of keeping in mind the purpose behind each of the probes. we linked lay understanding to information sources using probes, for example, ''how does sars affect a personÕs body?'' followed by ''can you tell me how you learned about this?'' we asked about the action of seeking information and connected this with the partic-ipantÕs current information needs. the two-part probe ''what questions did you have about sars and what caused you to look for information about [fill in with the topic of the question asked]'' is of this type. other actions concerning self, family, or community protection were connected to understanding of sars using probes such as ''for example, did you buy a facemask, vitamins, or do something else?'' ''why did you decide to [repeat preparation given by respondent]?'' and ''how is [repeat preparation given by respondent] going to help prevent sars?'' this instrument design was based on our research goals to link interactions between understanding, information received, and actions taken. the questions ask about the participantÕs sars experience over time, from the time prior to the outbreak and then ask the participant to project their own scenario about what they believe will happen in the coming weeks following the interview. the arrangement of the interview into time periods (before, during, and upcoming events related to the epidemic) facilitates the data analysis when looking at the interactions and influences between informa-tion received, lay understanding, and actions taken. we believe that this type of interview could be used during any epidemic outbreak. the strategy we used for the reduction and interpretation of our narrative data consisted of three stages. in the first stage, we identified the categories of sars epidemic-related events and concerns discussed by our participants. we did thematic coding, in which we ''let categories emerge from the data rather than assign them from a pre-defined list'' [ ] . using the qualitative software program, nvivo [ ] , we iteratively coded emergent categories by marking segments of text that are instances of actions the participant said they took, explanations given concerning sars, information sources used, and information needs expressed. the second stage consisted of reorganizing the events in the narrative into the correct chronological order. this was necessary because participantÕs stories and anecdotes were not always told in the same order that they occurred during the epidemic. the last stage used the time-ordered data from phase two in order to evaluate influences on actions taken. for each action identified during thematic coding (stage one), we looked at partic-ipantÕs explanations, reasoning process, and emotional state prior to the action. we began the process of coding by constructing a rudimentary coding scheme based on the interview probes and by reading through the first transcript. for example, we could anticipate that participants would discuss ''wearing face masks'' and ''washing hands'' as actions taken and these were included in the initial scheme. this coding scheme changed incrementally as we carefully scrutinized all the interview texts (from hong kong, taiwan, and toronto) resulting in the final version of the coding scheme in appendix b. this process is clarified using an illustrative example. the transcripts, in rough form, are read and the researchers specify codes at the phrase level, sentence level or paragraph level. for example, the code ''risk assessment of sars'' was assigned to the phrase (from participant ): in march, early march i started to hear about the sars virus that was in hong kong but it did not seem very, ahhh quite epidemic mode after seeing similar texts concerning the same type of expression, we assigned a more general code called ''sars risks'' to all similar instances in all interviews, such as in phrase (from participant ): however, it was on the news but they didnÕt put a lot of seriousness into the broadcast. each category was defined for further coding consistency. for example, ''information need: containment status'' was defined as ''an information need or question stated that is about any topic related to control of the outbreak (e.g., ''has the virus peaked?''). multiple codes could be assigned to the same text. spreads because itÕs in a really tight confined area [location: tightly confined area] like a hospital room [location: hospital room]'' the double underline is used when overlapping categories (i.e., [location: tightly confined area]) are assigned to text already coded in another category (i.e. ''really tight confined area''). the process of thematic coding resulted in a list of instances of actions, explanations, and information needs expressed by participants in our data. we also looked for ''new'' categories of entities and events that would help us to make sense out of what people were experiencing during the sars outbreak and what factors influenced their perceptions of the epidemic response. although not initially themes in our work, we also coded policy, location of events, persons involved, and other major categories that emerged from the data. from the codes that emerged, we get a sense of: ( ) the types of actions people took (e.g., avoiding others), ( ) social situations they observed during the epidemic (e.g., people are banned from entering someplace because of elevated temperature), ( ) types of actions the participants recommend doing for sars prevention (e.g., get proper rest), ( ) types of explanations described by participants about sars (e.g., cultural influences and cultural factors), ( ) the information needs participants expressed (e.g., participants wanted to know what the potential outcome was for a person who contracted sars), ( ) what emotions people expressed concerning sars (e.g., ''eerie feeling/freaked out''), and what information sources people consulted (e.g., tv media). we began to see some patterns emerging from our eight personal narratives. within the list of explanations of sars, there are none concerning the physiological processes of a virus within the body (because we did not observe a single instance in the data). the sars participants in the asian cities seemed to have a great knowledge of certain facts (about what actions to take). this is not surprising since they were living in places where the threat is presented on a daily basis (e.g., everyone wearing masks on the street) and they were bombarded with information in the media. what was interesting was that these two people felt a need for further information about the mechanisms behind the viral processes and not just a superficial list of what to do. another pattern observed was the expression of suspicion by participants from canada. many of the emotions that were expressed in the coding scheme inventory are related to fear and anxiety. participants, notably the toronto residents, expressed suspicion about a possible cover-up of outbreaks, (i.e., ''why did this occur in toronto and not in the us?''). these participants had questions and concerns about government policy [ ] . to illustrate how the thematic data can be employed to evaluate current guidelines, we used the coded narrative texts to further conduct a comparison of partici-pantsÕ knowledge of sars symptoms, treatment, transmission, and preventions with cdc web site information [ ] . we made this comparison using guidelines from the same time period as when the interviews occurred. to do this, we coded cdc guidelines using the same methodology described in section . . . we then took each sentence from interviews that were coded as a symptom, transmission mechanism, treatment or prevention, and compared those with sentences from the cdc guidelines. overall, participants had beliefs that were consistent with current understanding of sars, with almost % ( / ) of the sentences from the interviews concerning symptoms, transmission mechanism, treatment, or prevention of sars corresponding to those found in the cdc guidelines. such a high level of consistency would be very unlikely in a larger more diverse sample. reorganization of events was necessary to facilitate data reduction and to assist in the interpretation of the narratives. one result of this time ordering was unexpected and resulted in further separation of each personal narrative into several time segment blocks. for each participant, we found that some events were mentioned multiple times and signaled major changes in the participantÕs emotional state, actions taken, understanding, or informational needs and we marked these as ''trigger'' points for change. for example, as the outbreak in hong kong became more serious and more people were infected, the participantÕs behavior and reaction naturally changed leading to new actions taken, a greater understanding, and more attention focused on the daily news report. the data were separated for each narrative so that the end of each time segment block signals major shifts in thinking about the epidemic (e.g., ''and at that point it really got into my consciousness about this virus and that it was very serious''). examples of the ''triggers'' that propelled the participant to change their viewpoint and signaled the beginning of each new time period are marked in italic type in figs. and shown in the section below. we then performed the analysis described in section . . to capture the connections between the events in order to organize and standardize the relationship between information, lay understanding, and actions. we found that constructing visual representations of interactions was very useful for characterizing each overall causal explanation. to illustrate with an example, we use our hong kong participant. figs. - correspond to time segment blocks for that participant from the start of the epidemic (time period ) until the time the participant decided to leave hong kong (time period ). in fig. , we show that she was passively watching the news and did not feel that there was a heavy emphasis on the ''mysterious illness'' that was occurring in the ''new territories.'' her understanding of the disease was generated from these reports and primarily consisted of a belief that ''it was not affecting us.'' (because she is a westerner in hong kong) she did take one precaution, that is, to wash her hands more often and wipe her childÕs hands. this was based on her concern over her childÕs well being to; nevertheless, take precautions against the illness that she thought was ''like a cold or pneumonia.'' in the second time period, fig. , we began to see her concern increasing. this change was triggered by the the trigger leading to increased concern is shown in italic type. fig. . example of coded interactions from the hong kong participant: time period (from an increased awareness of sars as an epidemic to a decision to leave the region). the trigger leading to increased concern is shown in italic type. realization that her neighborhood bank teller lived at amoy gardens and that it could possibly spread to her family. she builds her understanding of sars, focusing on the model of transmission. all of her actions taken are based on this model. for the most part, she followed the guidelines presented in the media, except that she did not wear a mask, in spite of the fact that there was social pressure ''people wearing masks on the street,'' and that she also avoided walking past people because ''i didnÕt want somebody to sneeze or cough on me and me get caught in the drift of that and get it on me' ' we see major changes in anxiety level, actions taken (precautions), understanding, and informational factors in the third time period, shown in fig. . many interactions were recorded that form larger ''influence interrelationships.'' for instance, she made a decision to leave hong kong. this was strongly related to a friendÕs decision to leave as well. the friendÕs decision increased her anxiety and shock, pushing her to make the same choice. she stated that her friend (but she did not state she felt panic) was panicked due to an internet hoax that stated the airports of hong kong were closed and no one could get out. across all the narrative data, we looked at peopleÕs reasons for actions. the major influences on actions are in table below. one important influence on actions was the vocabulary used by an information source (in particular, mass media), which served as a catalyst for major changes in lay reaction. as an example, use of the word ''epidemic'' caused emotional and behavioral changes. a toronto resident stated that seeing the word ''epidemic'' was key ''uh, i wanted to know how fast it was spreading because if i thought it was an epidemic i would make the decision to stay home and not go to work.'' the hong kong resident provides another example of this. after seeing the headline ''sars an epidemic in hong kong,'' this lead her to conduct web searches, which in turn lead to further learning about transmission. she therefore updated her understanding of the virus through the web searches, learning that the ''virus lives on surfaces up to hours.'' these were considered a specific type of ''trigger'' based on source. these media triggers are ''emotionally loaded'' words that caused participants to experience major shifts in thinking about the epidemic. they were identified while reorganizing the narratives to consolidate all events (according to the participantsÕ perceptions) that happened in the same time period. participants stated certain media events (i.e., ''triggers'') over and over again in separate stories, linking different aspects of their experience. we found that there were several primary types of influences on expression (or realization) of an information need. these are listed in table . although partici- ''it kinda freaked me out'' --concern over family ''but since i did have a child'' perception of safety ''so that leads me to believe that the general public is somewhat safer'' because ''you have to'' (social pressure) ''so you have to wear the mask'' we considered line an ''information need'' statement. types of information need statements in the data were consolidated as table . this methodology leads to emerging hypotheses from our data that can be explored in subsequent work. these suggestions were derived after examination of the participant-stated relationships between coded themes (as described in section . . ). the descriptions of these emerging ideas refer back to figs. and . in fig. , we begin to see that epidemic decisions were not based on quick emotional reactions (panic) or social influences entirely. rather, they were based on strong connections between knowledge building, information gathering, and making decisions (e.g. whether to wear a mask). the participantÕs understanding of disease transmission and epidemic status (containment) influenced decisions either directly, or indirectly (through increasing negative emotions). evidence that many decisions in an epidemic are carefully considered and involve use of significant information gathering prior to the actual decision is consistent with some of the literature in public health [ ] -but not in the literature related to decisions in emergency situations [ ] . we found that as concern increased, participants became more aware of information until they felt the need to move beyond scanning to searching databases for information (passive viewing switched to active as fear increased). thus, we hypothesize ( ) that future studies will show this relationship between reactions of concern and increasing use of information sources to investigate the various actions to take during an epidemic. contrary to the effortful, and systemic information seeking described by participants that related to increasing concern, we saw several occurrences in the data when social factors lead to quick and resolute precautionary actions. for example, the participant described a change in her understanding of risk between time periods two (fig. ) and three (fig. ) ''and i spoke to my girlfriend and she said that she was going to leave hong kong and i was really shocked because she was the one that was like myself, just kind of sticking around and saying oh itÕs not a big deal and weÕll manage . . . and once i heard that she was leaving, then it put me into motion thinking i need to get out of here. this is not the place to be right now.'' social aspects tend to highly ''personalize'' the risk involved and alter thinking ''it can affect me.'' the hypothesis ( ) that emerges from this data is that information that personalizes the epidemic can affect the actions taken, leading to quick decisions to protect against infection. in terms of information seeking, the results we have found related to hypothesis are similar to those of van zuuren and wolfs [ ] and rees and bath [ ] described in section . as the personÕs concern (perceived degree of threat) increases during an epidemic, so does information seeking. however, we did not find any intentional avoidance of information that occurs in patients with a serious illness. in the epidemic situation, lack of information seeking was only observed when there was a perceived need to make a quick decision. the two observations made in the above paragraphs are consistent with dual-process models of social reasoning; the elaboration likelihood model [ ] , and the heuristic-systematic model [ ] . these models predict that there are two routes of information processing. in one route information is processed and decisions are made fast and superficially, and in the other route people engage in more time consuming, effortful, and systematic information processing and problem solving. these models, specifically, chaiken et al. [ ] predict that the fast and superficial (like hypothesis ) information-processing route is used in situations when people are not motivated and/or do not have the ability for making decisions. in the case of people in an epidemic situation, future work may pinpoint the situational factors that result in thoughtful versus hasty actions. we have outlined a methodology for characterizing factors that affect information gathering, comprehension, and preventative behavior by lay people during epidemics. we approached the task using literature from all three areas as a framework, where the cognitive aspects underlying acts (behavior) is given a major focus. this perspective suggests that decisions and actions are largely based on individualsÕ cognitive representations of events, which are in turn shaped by prior knowledge and new information, as well as by social and emotional factors. given the complexity of the influencing factors, and the interconnections among these variables, a structured qualitative approach was considered as most appropriate for gathering data. public health guidelines concerning ways to tailor communication describe aspects of messages that are effective during a crisis event [ ] . the goal of this methodology is to be able to specify ways to increase compliance with guidelines and how to reduce behaviors that increase risk. use of this methodology captures the major themes that emerge related to information needs and actions. this allows officials to address the publicÕs concerns and learn about the actions they are taking. yet, the major contribution of this methodology is related to developing detailed causal/temporal models showing the influences between factors. with this, it is possible to identify problematic situational variables and intervene when they may lead people to make rash decisions. this methodology was applied to study lay reactions to the sars virus outbreak of but might be applied to other viral infectious disease outbreaks, either naturally occurring or through terrorism. having a better understanding of the reactions of the layperson will lead to developing information support systems as well as guidelines for preparedness in the event of a future epidemic. information provided through guidelines or ''just-in-time'' (depending on the needs) could help the lay public to respond appropriately during future epidemics. results from studies using these methods can also be used to educate professionals (e.g., hospital administrators, the media, and government policy makers) by providing models to explain, for example, what strategies laypersons use to assess the situation during outbreaks of an infectious disease. buy supplies (e.g., anti-bacterial wipes) centers for disease control (cdc) press release. cdc announces new goals and organizational design cdc imperative : timely, accurate and coordinated communications outbreak of severe acute respiratory syndrome in hong kong special administrative region: case report on user studies and information needs communication for health and behavior change: a developing country perspective question-negotiation and information seeking in libraries ask for information retrieval models in information behaviour research emr: re-engineering the organization of health information reasoning about childhood nutritional deficiencies by mothers in rural india: a cognitive analysis naturalistic decision making: where are we now situation awareness in emergency medical dispatch looking for information: a survey of research on information seeking, needs, and behavior attention and avoidance: strategies in coping with aversiveness. seattle: hogrefe and huber interesting effects of information and coping style in adapting to gynaecological stress: should a doctor tell all monitoring and blunting coping styles in women prior to surgery styles of information seeking under threat: personal and situational aspects of monitoring and blunting a new method for studying patient information needs and information seeking patterns information-seeking behaviour of women with breast cancer a first look at communication theory the story of the great influenza pandemic of and the search for the virus that caused it the coming plague: newly emerging diseases in a world out of balance how to vaccinate , people in three days: realities of outbreak management kaleidoscoping public understanding of science on hygiene, health, and the plague: a survey in the aftermath of a plague epidemic in india community reaction to bioterrorism: prospective study of simulated outbreak the public and the smallpox threat narrative analysis. newbury park: sage publications acts of meaning introducing narrative psychology, self, trauma, and the construction of meaning narrative psychology narrative and the cultural construction of illness and healing models and motives cultural knowledge as resource in illness narratives: remembering through accounts of illness basics of qualitative research techniques and procedures for developing grounded theory the nvivo qualitative project book some further steps in narrative analysis. the journal of narrative and life history qualitative data analysis. california naturalistic inquiry understanding public response to disasters communication and persuasion; central and peripheral routes to attitude change heuristic and systematic information processing within and beyond the persuasion context you can exercise your way out of hiv and other stories: the role of biological knowledge in adolescentsÕ evaluation of myths cognitive psychological studies of representation and use of clinical practice guidelines this work is supported in part by nlm training grant lm - . we thank david kaufman for reading and reviewing the manuscript. key: cord- - cz agx authors: babyn, paul s.; chu, winnie c. w.; tsou, ian y. y.; wansaicheong, gervais k. l.; allen, upton; bitnun, ari; chee, thomas s. g.; cheng, frankie w. t.; chiu, man-chun; fok, tai-fai; hon, ellis k. l.; gahunia, harpal k.; kaw, gregory j. l.; khong, pek l.; leung, chi-wai; li, albert m.; manson, david; metreweli, constantine; ng, pak-cheung; read, stanley; stringer, david a. title: severe acute respiratory syndrome (sars): chest radiographic features in children date: - - journal: pediatr radiol doi: . /s - - - sha: doc_id: cord_uid: cz agx background: severe acute respiratory syndrome (sars) is a recently recognized condition of viral origin associated with substantial morbidity and mortality rates in adults. little information is available on its radiologic manifestations in children. objective: the goal of this study was to characterize the radiographic presentation of children with sars. materials and methods: we abstracted data (n= ) on the radiologic appearance and course of sars in pediatric patients with suspect (n= ) or probable (n= ) sars, diagnosed in five hospital sites located in three cities: toronto, singapore, and hong kong. available chest radiographs and thoracic cts were reviewed for the presence of the following radiographic findings: airspace disease, air bronchograms, airways inflammation and peribronchial thickening, interstitial disease, pleural effusion, and hilar adenopathy. results: a total of patients (suspect= , probable= ) were evaluated for sars. patient ages ranged from . months to years and . months (average, years and months) with a female-to-male ratio of : . forty-one patients ( . %) were in close contact with other probable, suspect, or quarantined cases; patients ( . %) had recently traveled to who-designated affected areas within days; and patients ( . %) were transferred from other hospitals that had sars patients. three patients, who did not have close/hospital contact or travel history to affected areas, were classified as sars cases based on their clinical signs and symptoms and on the fact that they were living in an endemic area. the most prominent clinical presentations were fever, with a temperature over °c ( %), cough ( . %), rhinorrhea ( . %), myalgia ( . %), chills ( . %), and headache ( . %). other findings included sore throat ( . %), gastrointestinal symptoms ( . %), rigor ( . %), and lethargy ( . %). in general, fever and cough were the most common clinical presentations amongst younger pediatric sars cases (age< years), whereas, in addition to these symptoms, headache, myalgia, sore throat, chills, and/or rigor were common in older patients (age≥ years). the chest radiographs of . % of patients were normal. the most prominent radiological findings that were observed in the remaining patients were areas of consolidation ( . %), often peripheral with multifocal lesions in . %. peribronchial thickening was noted on chest radiographs of . % of patients. pleural effusion was observed only in one patient (age years and . months), whereas interstitial disease was not observed in any patient. conclusion: in pediatric cases, sars manifests with nonspecific radiographic features making radiological differentiation difficult, especially from other commonly encountered childhood respiratory viral illnesses causing airspace disease. the radiographic presentation of suspected sars cases ranged from normal to mild perihilar peribronchial thickening. the radiographic presentations, as expected, were relatively more pronounced in the sars probable cases. abstract background: severe acute respiratory syndrome (sars) is a recently recognized condition of viral origin associated with substantial morbidity and mortality rates in adults. little information is available on its radiologic manifestations in children. objective: the goal of this study was to characterize the radiographic presentation of children with sars. materials and methods: we abstracted data (n= ) on the radiologic appearance and course of sars in pediat-ric patients with suspect (n= ) or probable (n= ) sars, diagnosed in five hospital sites located in three cities: toronto, singapore, and hong kong. available chest radiographs and thoracic cts were reviewed for the presence of the following radiographic findings: airspace disease, air bronchograms, airways inflammation and peribronchial thickening, interstitial disease, pleural effusion, and hilar adenopathy. results: a total of patients (suspect= , probable= ) were evaluated for sars. patient ages ranged from . months to years and . months (average, years and months) with a female-tomale ratio of : . forty-one patients ( . %) were in close contact with other probable, suspect, or quarantined cases; patients ( . %) had recently traveled to who-designated affected areas within days; and patients ( . %) were transferred from other hospitals that had sars patients. three patients, who did not have close/hospital contact or travel history to affected areas, were classified severe acute respiratory syndrome (sars) was first identified in guangdong province in southern china in november [ , ] . sars is a severe atypical pneumonia associated with substantial morbidity and mortality rates in adults, now believed to be caused by a novel coronavirus [ , , , , , ] . outbreaks have been reported in asia, europe, north america, and australia [ ] . as of september , a cumulative total of , probable cases and deaths have been reported from countries [ ] . to date, the outbreak of sars in canada has resulted in probable cases and deaths; singapore had probable cases and deaths; hong kong had , probable cases and deaths [ , ] . the diagnosis of sars currently rests upon clinical and epidemiological criteria as defined by the world health organization (who), since definitive tests for sars have not yet been developed and validated [ ] . a suspect case is disease in a person with documented fever (temperature > °c), one or more respiratory tract symptoms (including cough, shortness of breath, difficulty breathing), and close contact with a person believed to have had sars (living with, caring for, or having had direct contact within days of onset of symptoms, exposure to respiratory secretions and/or body fluids of a person with sars) and/or a history of travel (within days of onset of sars symptoms) to an endemic geographic area with documented foci of illness transmission. a probable case is defined as a suspect case with chest radiographic findings of pneumonia, acute severe respiratory distress, or an unexplained respiratory illness resulting in death with autopsy results demonstrating the pathology of acute respiratory distress syndrome without an identifiable cause. probable cases of sars are similar to suspect cases, but often have a more severe illness, with progressive shortness of breath and difficulty breathing, as well as radiographic signs of atypical pneumonia [ , , ] . descriptions of the sars outbreaks in adult patients from toronto [ , , , ] , singapore [ , ] , and hong kong [ , , , , ] have recently been reported. to date, the clinical and radiographic findings in children suspected of having sars have been limited or combined with adult data [ , ] . this article presents the initial chest radiographic findings collated from children diagnosed as probable or suspect sars cases during the recent sars outbreak in toronto, singapore, and hong kong. the limited previously published material is included to provide as complete a pediatric series as possible. a total of pediatric patients, fitting the who case definition [ ] or a modification of this definition [ ] for suspect or probable sars, admitted to hospital from late february to mid-may , were included in this report. patients in this report were admitted to one of the following five hospitals: (a) the hospital for sick children (hsc) in toronto; (b) tan tock seng hospital (ttsh) in singapore; (c) prince of wales hospital (pwh), (d) princess margaret hospital (pmh), or (e) queen mary hospital (qmh) in hong kong. we abstracted data retrospectively from review of patientsÕ medical records for patient demographics, exposure category, clinical presentations, and radiological findings. the hospitalization period (length of stay in the hospital) for these patients varied from days to month after the onset of symptoms. the exposure category included the possible mode of transmission through close contact, health-care setting, and/or travel to, or living in, endemic areas. clinical presentations were reviewed for as sars cases based on their clinical signs and symptoms and on the fact that they were living in an endemic area. the most prominent clinical presentations were fever, with a temperature over °c ( %), cough ( . %), rhinorrhea ( . %), myalgia ( . %), chills ( . %), and headache ( . %). other findings included sore throat ( . %), gastrointestinal symptoms ( . %), rigor ( . %), and lethargy ( . %). in general, fever and cough were the most common clinical presentations amongst younger pediatric sars cases (age< years), whereas, in addition to these symptoms, headache, myalgia, sore throat, chills, and/or rigor were common in older patients (age ‡ years). the chest radiographs of . % of patients were normal. the most prominent radiological findings that were observed in the remaining patients were areas of consolidation ( . %), often peripheral with multifocal lesions in . %. peribronchial thickening was noted on chest radiographs of . % of patients. pleural effusion was observed only in one patient (age years and . months), whereas interstitial disease was not observed in any patient. conclusion: in pediatric cases, sars manifests with nonspecific radiographic features making radio-logical differentiation difficult, especially from other commonly encountered childhood respiratory viral illnesses causing airspace disease. the radiographic presentation of suspected sars cases ranged from normal to mild perihilar peribronchial thickening. the radiographic presentations, as expected, were relatively more pronounced in the sars probable cases. keywords chest ae severe acute respiratory syndrome (sars) ae radiography ae ct ae children the following signs and symptoms: fever, chills, body ache, cough, sore throat, rhinorrhea, dyspnea, tachypnea, crackles, headache, dizziness, hypoxemia, malaise, myalgia, rigor, lethargy, and gastrointestinal symptoms including vomiting and diarrhea. microbiological investigations from the toronto site (hsc, n= ) included nasopharyngeal swabs for direct antigen detection, and culture of respiratory viruses including respiratory syncytial virus, influenza a and b, parainfluenza , and , and adenovirus. we also included the following investigations: a nasopharyngeal swab for sars-associated coronavirus reverse-transcriptase polymerase chain reaction (rt-pcr), a throat swab for bacterial culture and mycoplasma pneumoniae pcr, a stool sample for electron microscopy, and two blood cultures. the rt-pcr test used to detect the sars-associated coronavirus in toronto was developed in-house. from the hong kong sites (pwh and pmh, n= ), paired acute and convalescent sera/feces samples were collected from some patients. the microbiological investigations included viral culture, stool and throat gargle rt-pcr, bacterial culture of blood and sputum, serology, and nasopharyngeal aspirates (npa) for virology. the npa was assessed by rapid immunofluorescent antigen detection for influenza a and b, parainfluenza types , and , respiratory syncytial virus, and adenovirus. the rt-pcr test used to detect the sars-associated coronavirus in hong kong was developed in-house. at the time of this study, patients from singapore were managed on the basis of clinical, epidemiological, and radiographic evidence. microbiological tests were not routinely performed on any patient. all available initial and follow-up chest radiographs obtained in these patients were interpreted by experienced pediatric or general radiologists. these radiographs were not reviewed at a central site, instead the films were read at each participating center independently. the chest radiographs were reviewed for the presence of standard radiographic findings of pulmonary infection in children. specific evaluation criteria included: the presence or absence of pulmonary overinflation, bronchial wall thickening, interstitial disease, atelectasis, airspace disease (ground-glass opacification, patchy, focal or lobar consolidation), nodules, pleural effusion, air bronchogram, hilar adenopathy, and extrapulmonary air. other radiological features, if present, were also noted. a combination of posteroanterior, lateral, and portable anteroposterior views was available. a standard radiographic technique was utilized, with most patients having portable examinations with anteroposterior views only. if a thoracic ct was obtained, the ct findings were also reviewed. a standard ct or thin-section ct technique was utilized as described elsewhere [ ] . from a total of cases, patients (from all the study sites) initially under suspicion of having sars were excluded from the study, as another etiology (other pneumonias or other underlying disease) was determined. patients were excluded from this study if they had another known disease potentially affecting the chest radiographic appearance. institutional review board approval was obtained from two sites, toronto and hong kong, and was waived for singapore. a total of pediatric patients were diagnosed with sars (suspect= ; probable= ) in toronto, singapore, and hong kong. demographic data, exposure category, clinical presentation, and radiographic findings of these cases from the various sites are shown in tables , , and with an overall summary shown in table . patient ages ranged from . months to years and . months (average, years and months) with a female-to-male ratio of : . forty-one patients ( . %) were in close contact with other probable, suspect, or quarantined cases; patients ( . %) had recently traveled to the affected areas; patients ( . %) were transferred from other hospitals with admitted sars patients. three patients from the hong kong patient cohort did not have close contact, hospital contact, or travel history to affected areas, but were included in the study on the basis of their clinical signs and symptoms and because they were living in an endemic region. these patients were classified as probable sars cases, which was possibly community acquired. in toronto, the patient population (n= ) average age was years with a female:male ratio of : . amongst these patients, close contact ( %) with sars probable, suspect, or quarantined family members was the most common mode of possible sars exposure. potential sars exposure through hospital contact or travel to who-defined affected areas within days prior to onset of symptoms was observed in . % and . % of patients, respectively. from the various hospital sites in singapore, the patient population (n= ) average age was years and months with a femaleto-male ratio of : . the mode of possible sars exposure through close contact ( . %) was greater than exposure due to travel ( . %). in hong kong, the patient population (n= ) average age was years and months with a female-to-male ratio of : . the mode of possible sars exposure through close contact ( . %) was also high amongst these patients, whereas three patients ( . %) did not have a history of contact or travel exposure but were living in an endemic region. overall, close contact with a known sars case (family member) was the most common mode of possible sars exposure accounting for cases ( . %). health-care settings accounted for seven cases ( . %) including transfer from other hospitals and, in one of these cases, a visit to a family physician. travel to an endemic region was seen in ten cases ( . %), whereas no known mode of sars exposure was identified in three cases. the most common clinical manifestations noted from toronto patients were fever ( %), cough ( . %), rhinorrhea ( . %), and diarrhea ( . %). from the singapore patient cohort, fever ( %) and cough ( . %) were the most common clinical features. from the hong kong patient cohort, in addition to fever ( %) and cough ( . %), myalgia ( . %), chills ( . %), rhinorrhea ( . %), and rigor ( . %) were also commonly reported. overall, the most common clinical presentation was fever with a temperature over °c ( %), cough ( . %), rhinorrhea ( . %), myalgia ( . %), chills ( . %), and headache ( . %). other reported findings included sore throat ( . %), diarrhea ( . %), rigor ( . %), and lethargy ( . %). in general, fever and cough were the most common clinical presentation amongst younger pediatric sars cases (age< years), whereas, in addition to these symptoms, headache, myalgia, sore throat, chills, and/or rigor were reported in older patients (age ‡ years). only one teenager with probable sars (toronto, age years and . months) developed respiratory distress and required oxygen. from the toronto patient cohort (n= ), the nasopharyngeal swab specimens were negative for the sars-associated coronavirus (toronto rt-pcr test). however, most of the patients who had clinically defined sars and were tested for microbiological agents (n= ) in hong kong had either serological or rt-pcr evidence of infection for the sars-associated coronavirus (hong kong rt-pcr test). four patients were rt-pcr positive on npa; two patients were serology positive; stool rt-pcr and throat gargle rt-pcr were positive for three patients; and stool rt-pcr was positive in one patient. all three sars cases with no history of contact in hong kong were found to have positive paired acute and convalescent serum test results. the sars-associated coronavirus was isolated from npa in two patients and only one patient out of the ten included for microbiological testing was negative for rt-pcr. the chest radiographs of . % of patients were normal. the most prominent radiological findings in the remaining patients were patchy infiltrates, opacities, and/ or areas of consolidation ( . %) with multifocal lesions observed in . %. the location of consolidation was predominantly within the lower lobes. perihilar peribronchial thickening was noted in . % of cases. figures , , , and show the various common radiographic findings. pleural effusion was observed only in one patient, whereas interstitial disease was not observed in any patient. hilar adenopathy, extensive pleural effusions, lung abscess, pneumatocele, or pneumothorax were not seen. these radiographic findings resolved in the majority of cases within a -week interval. ct scans for some patients were obtained only in hong kong (table ) . ct scans showed unifocal or multifocal, central and/or peripheral regions of consolidation and/or ground-glass opacities. figures and b show ct scans obtained from two patients. in general, ct showed more extensive airspace consolidation and ground-glass attenuation than chest radiographs, but no evidence of hilar adenopathy, pneumothorax, or pneumomediastinum was noted in our patient population. as far as we know, to date no pediatric deaths have been reported amongst toronto, hong kong, or singapore patient cases that were included in this study. pneumonia is one of the most common serious infections of childhood with significant morbidity and mortality rates worldwide. in the united states, the reported mortality rate due to pneumonia and influenza for [ ] . based on prospective data collected from pediatric studies of community-acquired lower respiratory tract infections, viral respiratory tract pathogens are responsible for the majority of diagnosed infections in the developed world, particularly in the younger age group [ , , , ] . sars is a new viral disease that must now be considered when faced with a child with fever and respiratory symptoms. highly contagious, sars was first identified in guangdong province in southern china late last year. as in other epidemics of the past, trade and travel have sped up sars transmission between disparate populations. the impact upon affected regions has been significant, both medically and economically. since sars was first identified, a total of casualties and , probable sars cases have been reported from canada, singapore, and hong kong with additional thousands quarantined. to date there have been limited reports in children [ , ] . the great majority of sars victims have been adults [ , , , , , , , , , , ] with a fatality rate of . % based on who surveillance data [ ] . over the past few months remarkable progress has been made in defining the clinical features and etiology of sars. microbiologic evaluation has now revealed a fig. a -month-old boy with probable sars from household contact. clinical presentation included fever ( °c), cough and rhinorrhea. initial chest radiograph revealed mild perihilar peribronchial thickening and patchy, multifocal infiltrates at the left lung base fig. a -month-old boy with probable sars from household contact presented with fever ( . °c) and cough. initial chest radiograph showed a focal area of airspace opacification in the right lower lobe fig. a -month-old girl with probable sars with recent travel history to guangdong province, south china, presented with fever and cough. initial chest radiograph revealed a patchy opacity in right upper lobe and a mild peribronchial thickening extending into the lower lobes. subsequent radiographs showed decreased opacity within the right upper lobe and an increased density within the right infrahilar region fig. a -year-old girl with probable sars exposed through household contact. signs and symptoms of the patient at admission included fever ( . °c), cough, dyspnea, hypoxemia, and bilateral crackles. the initial radiograph revealed dense airspace disease involving the right middle lobe and posterior left lower lobe novel coronavirus as the etiologic agent of sars [ , , , , ] . clinically, children show similar symptoms to those already reported in adults including fever, cough, headache, and myalgia. however, dyspnea, malaise, and hypoxemia are less commonly encountered in childhood. the typical pediatric presentation is rapid onset of high fever with cough. compared with adults, children with sars seem to have a milder clinical course, especially for those under the age of years [ , ] . currently, the who case definitions for suspect or probable sars rely upon patient contact, travel history to endemic areas within days, and commonly encountered clinical and radiographic criteria. many children that were initially suspected of having sars were eventually excluded upon availability of the results of standard microbiologic investigations. for example, at one institution (toronto) we had ten children present with clinical and epidemiological criteria consistent with a diagnosis of suspect or probable sars, but who were later shown to have other infections. these other infections included viral respiratory tract infections such as adenovirus, influenza (a and b) , parainfluenza, and respiratory syncytial virus and bacterial infections, such as streptococcus pneumoniae bacteremia. further, using the current criteria, there are likely to be false-negative cases as well. some children may be inappropriately thought not to have sars due to our incomplete knowledge of the full extent of sars clinical presentations, especially at the early or mild stage of the disease. a few adult close contacts have reported a mild, febrile illness without definite respiratory signs or symptoms suggesting that the illness might not always primarily involve the respiratory tract. this appears to be true in children as well, with some in our study having minimal or no clear respiratory symptoms and a nonspecific febrile illness despite extensive contact history [ ] . although gastrointestinal symptoms are usually absent, some children reported vomiting and/or diarrhea [ , , ] , while several adults have presented solely with severe abdominal pain. the relative infectivity of these patients remains unclear and until more is learned, caution and full infection control procedures are recommended. significant effort still lies ahead to fully characterize the signs and symptoms of sars across all ages and especially to develop reliable means of differentiating it from other lower respiratory tract infections. accurate identification of the causative agent in these situations should hopefully lead to more specific and sensitive diagnostic tests to simplify sars diagnosis. preliminary work with rt-pcr tests for sars is promising; however, it is not yet clear how accurate these tests are, particularly for commonly used nasopharyngeal samples as shown in this study and by peiris et al. [ ] . radiographic findings in children may be normal or may demonstrate airspace disease, which may present as ground-glass opacities or focal, lobar, or multifocal consolidation. other radiographic findings included perihilar peribronchial thickening and linear atelectasis. we did not consider mild peribronchial thickening as pneumonia and these children were classified as suspect sars. as in adults, regions of airspace disease predominated in the lower lobes, especially peripherally, but were also seen elsewhere. distinguishing between atelectasis and consolidation can be difficult fig. high-resolution ct of a -year-old girl who presented with persistent fever for week with chills, rigors, rhinorrhea, and myalgia. there is mixed airspace consolidation and ground-glass opacity in the left lower lobe fig. a , b a -year-old girl, who presented with fever, chills, rigors, myalgia, and headache for days. she had a history of hospital contact with probable sars patients. a chest radiograph on admission is unremarkable with no definite consolidative change. b high-resolution ct on the same day shows a focal consolidation at the right lung base in daily practice. areas of segmental atelectasis are common in viral disease and may often be multiple and fleeting. adenopathy, infrequently encountered with viral diseases [ ] , was not seen in our patients. with clinical recovery, complete clearing of chest radiographs were noted in our patients similar to other reports [ , ] . it is still unclear what the long-term sequelae of sars infection will be on subsequent lung development. in adults, radiographic findings may be more extensive, and also include unilateral or multifocal and bilateral patchy or confluent areas of airspace consolidation or ground-glass opacities [ , , , ] . chest radiographs may be normal during the early febrile prodrome or with mild disease and may progress later on. opacities are most often peripheral or mixed central and peripheral [ , ] . in the more advanced stage of the disease, a widespread ground-glass opacification (likely representing progression to ards) and diffuse patchy or lobar consolidation have also been reported [ , ] . interstitial disease is rare and pleural effusion is uncommon. resolution may occur early on. diffuse miliary disease has been reported in one patient [ ] . ct findings in adults with probable sars have shown predominantly subpleural focal consolidation or ground-glass opacities [ , , , ] . these findings occur predominantly in the lower lobes and may be unifocal or multifocal. less common findings include thickening of interlobular septa and intralobular interstitium, the crazy paving pattern, and spontaneous pneumomediastinum. air bronchograms may be seen. mediastinal nodes, effusions, or central pulmonary emboli have not been observed. chest ct has been helpful in differentiating suspect from probable cases by demonstrating lung findings - days before they become radiographically apparent [ ] . our study showed similar ct features to those previously described with unifocal and multifocal consolidation and ground-glass opacities. we did not observe any of the less common features such as the crazy paving pattern or septal thickening. ct scans were obtained at one site only and were generally used to document early lung findings when the initial chest radiograph was normal or equivocal and suspicion for sars was high. ct scans of the pediatric chest are not routinely needed in evaluation of lower respiratory tract infection, but are generally reserved for investigation of suspected complications including pulmonary abscess, empyema, pulmonary necrosis, recurrent infection, or in immunocompromised individuals [ ] . since the clinical presentation in most of our pediatric cases was mild, ct was not considered necessary in two sites (toronto and singapore). for the hong kong patients (pwh and pmh patient cohort), chest ct was used for patients with suspected sars but with normal chest radiographs, patients with a moderate to severe clinical course of the disease, and patients without contact history. use of ct may be justified if management depends upon positive lung findings; however, suspect sars patients were also admitted and managed in a similar fashion to those with positive chest radiograph findings. it is still unclear whether the infectivity of suspect sars patients is similar to or decreased relative to those with positive radiographic findings. radiography has two major roles in sars. the first role is to recognize pulmonary disease in a patient with clinical symptoms of sars and contact history but who may not have cough. the second role is to recognize radiographic changes that are more characteristic of other diseases including bacterial or granulomatous infections. it is important to differentiate sars from other respiratory infection(s) commonly encountered in children. although, many children with viral lower respiratory infection present clinically with bronchiolitis, it is often impossible to distinguish clinically and/or radiologically between viral and bacterial infections [ ] . while its radiologic manifestations are nonspecific, sars appears similar to other viral infections encountered in children. certain radiographic findings are uncommon in sars, including extensive pleural effusions, pneumothorax, pneumatocele, and lung abscess. these findings were not encountered in our patient population, with exception of one patient with a small pleural effusion (table , probable case no. ). many patients were initially clinically thought to have tuberculosis or other infections, but the lack of radiographic findings such as adenopathy, cavitation, or pleural effusion may aid in suggesting sars or assist in excluding other disorders. recognition of the presence of radiographic changes which are atypical for sars, such as adenopathy and significant pleural effusion, may help to guide therapy as well as show the need for isolation. once the association with travel or case contact is lost in a community, clinical and radiographic recognition of the disease will become increasingly important especially if rapid diagnostic tests remain unavailable. our experience and that of others suggests little risk of transmission from child to adult; however, this remains to be substantiated. although the mechanisms of sars transmission remain to be fully elucidated, the most likely route of transmission is by large droplet and contact [ , ] . data from hong kong have shown the potential of sars-associated coronavirus to persist in stool or urine of sars patients and maintain its viability on various contact surfaces for extended periods [ ] . health-care workers are particularly at high risk, and there is potential for infection in the radiology department. we recommend extreme vigilance in application of infection control practices. further, the use of portable techniques in the ward, where a child can be maintained in proper isolation, helps to minimize the risk of sars virus transmission to staff and other patients. clinicians and radiology technologists need to use appropriate precautions during patient contact including hand hygiene, airborne measures (n- masks, capable of filtering out at least % of particles of a particular diameter), and contact precautions (e.g., caps, gowns, and gloves). goggles or visors are also recommended during direct patient contact, especially for aerosol-generating procedures such as suction or intubation [ ] . cleansing of all radiographic equipment and rooms is important and consideration must be given to ensuring safe patient flow [ ] . training and audit of inappropriate use of infection control measures have been documented as significant factors leading to health-care worker transmission. other factors include failure to apply appropriate isolation precautions to known sars cases or cases which have not yet been identified as sars and, finally, infected workers continuing to work despite infection. it is possible that all respiratory infections at initial presentation will need to be regarded as potential sars cases until proven otherwise. the retrospective nature of our study and the fact that we gathered data from multiple institutions are limiting factors. it is likely that the application of the case definitions was variable to some degree across the different communities and we lack knowledge as to whether the virus remains the same across these three distinct clusters. at this point we cannot be sure that all cases were indeed sars, and potentially other etiologies may have been included. limiting diagnosis to contact with a known case, although a valuable criterion, can lead to false-positive and false-negative cases especially as the disease spreads into the broader community [ ] . community spread has not been identified in toronto and singapore; however, hong kong has encountered this problem at pwh and pmh where three rt-pcr confirmed sars cases were reported without definite contact history. although standard nomenclature was used, other potential limitations of sars diagnosis included the fact that we relied upon local interpretation of radiographs and review of radiology reports, which may be subject to some variation in interpretation of images. in conclusion, sars in children manifests with nonspecific radiographic features making radiological differentiation difficult, especially from other commonly encountered childhood respiratory viral illnesses causing airspace disease. the radiographic presentation of suspect sars cases ranged from normal or mild perihilar peribronchial thickening; however, the radiographic presentation, as expected, was relatively more pronounced in the probable sars cases with airspace disease including ground-glass opacification and consolidation. severe acute respiratory syndrome (sars) outbreak of severe acute respiratory syndrome-worldwide a novel coronavirus associated with severe acute respiratory syndrome sars coronavirus sequencing identification of a novel coronavirus in patients with severe acute respiratory syndrome summary on major findings in relation to coronavirus by members of the who multi-centre collaborative network on sars aetiology and diagnosis identification of severe acute respiratory syndrome in canada coronavirus as a possible cause of severe acute respiratory syndrome severe acute respiratory syndrome (sars) cumulative number of reported probable cases of sars cumulative number of reported probable sars cases in canada severe acute respiratory syndrome (sars) preliminary clinical description of severe acute respiratory syndrome update no. -severe acute respiratory syndrome severe acute respiratory syndrome in the city of hanoi, vietnam; the peopleÕs republic of china including the hong kong special administrative region clinical features and short-term outcomes of patients with sars in the greater toronto area clinical course and management of sars in health-care workers in toronto: a case series identification and containment of an outbreak of sars in a community hospital preventing local transmission of sars: lessons from singapore severe acute respiratory syndrome (sars) in singapore: clinical features of index patient and initial contacts a cluster of cases of severe acute respiratory syndrome in hong kong a major outbreak of severe acute respiratory syndrome in hong kong outbreak of severe acute respiratory syndrome in hong kong special administrative region: case report sars: experience at prince of wales hospital, hong kong epidemiological determinants of spread of causal agent of severe acute respiratory syndrome in hong kong clinical presentations and outcome of severe acute respiratory syndrome in children thin-section ct of severe acute respiratory syndrome: evaluation of patients exposed to or with the disease deaths: leading causes for pneumonia due to viral and atypical organisms and their sequelae etiology of community-acquired pneumonia in hospitalized children childhood community-acquired pneumonia etiology and treatment of community-acquired pneumonia in ambulatory children children hospitalized with severe acute respiratory syndrome-related illness in toronto outbreak of severe acute respiratory syndromeworldwide radiological appearances of recent cases of atypical pneumonia in hong kong sars: imaging of severe acute respiratory syndrome clinical progression and viral load in a community outbreak of coronavirus-associated sars pneumonia: a prospective study comparative full-length genome sequence analysis of sars coronavirus isolates and common mutations associated with putative origins of infection aetiology: kochÕs postulates fulfilled for sars virus roentgenographic features of common pediatric viral respiratory tract infections lower respiratory infections in children rationalised prescribing for community acquired pneumonia: a closed loop audit severe acute respiratory syndrome (sars): information for clinicians sars can live on common surface severe acute respiratory syndrome (sars): infection control key: cord- -biundkbv authors: shek, daniel t. l. title: protests in hong kong ( – ): a perspective based on quality of life and well-being date: - - journal: appl res qual life doi: . /s - - - sha: doc_id: cord_uid: biundkbv triggered by the fugitive offenders and mutual legal assistance in criminal matters legislation (amendment) bill in hong kong (extradition bill), many protests have taken place in hong kong in – . using a perspective based on quality of life and well-being in different ecological systems, it is argued that the process of introducing the bill is the “heat” which has ignited the “fuels” represented by pre-existing and new issues in quality of life and well-being. these issues included distrust in the central government, lack of national identity, political dissatisfaction, economic strains, mental health threats, drop in family quality of life, lack of life skills education, lack of evidence-based national education in the formal curriculum, slow response of the government, and alleged excessive use of force by the police. the fire has been intensified by “four strong winds”, including disinformation and misinformation, anonymity of the protesters, public support for the students, and support given by parties outside hong kong. possible solutions in terms of promotion of quality of life and well-being with reference to the fire triangle are discussed. are well-designed training and operation manuals for protests and strikes which can be easily downloaded from the internet. fifth, vandalism has been extensive in the social event. these included damage of sets of traffic lights, . km of railings along the road, and , square meters of paving blocks (yau ) which require some hk$ million to repair. besides, there was damage of mass transit railway stations and light railway stations, assault and doxing people holding contrary political views, and damage of shops owned by those who did not support the social movement (rthk radio ). perhaps the most striking examples are the damage of the legislative council building on july , and the occupation of the chinese university of hong kong and the hong kong polytechnic university in november . besides, the use of foul language and physical violence to informally "settle" interpersonal conflicts was not uncommon in the movement. sixth, despite the great extent of violence and vandalism, public condemnation of such behavior was not strong. some people even show support for the use of violence in the social movement. for example, a survey showed that roughly % of the respondents supported the use of violence as a tactic and more than half of the pro-democracy respondents endorsed the use of laser pointers against the police (sum ) . finally, the social event is highly political in nature. although its origin was to protest against the extradition bill, it has gradually evolved into a movement with the slogan of "five demands, not one less". these five demands include "full withdrawal of the extradition bill", "retracting the classification of protesters as 'rioters'", "amnesty for arrested protesters", "an independent commission of inquiry into alleged police brutality", and "dual universal suffrage, meaning for both the legislative council and the chief executive" (wong b) . besides, the slogan of "liberate hong kong, revolution of our time" emerged as the social event moved on. during the social movement, protesters have placed advertisements in foreign newspapers and waved us and uk flags during the protests, appealing for support from foreign governments. obviously, quality of life has been much hampered in the social movement. first, the economy has slowed down because of the social unrest. for example, the number of tourists has dropped by % (cheng ) and the unemployment rate has been climbing in the past few months. second, protests have created much disturbance to the ordinary lives of people. for example, during the occupation of the chinese university of hong kong, the east railway system service was much disturbed and the main highway joining the eastern part of the new territories was blocked. the cross-harbor tunnel was also out of service during the occupation of the hong kong polytechnic university by the protesters. as a result, workers had to take leave involuntarily or spent much longer traveling time. third, the social movement has been divisive and polarized for people with different political views. for those who support the protesters and five demands, they are called "yellow ribbons". on the other hand, those who do not support the protesters, they are called "blue ribbons". in many families, social groups, and work settings, people have become alienated and have conflicts with each other (chow ) . finally, the social movement has created well-being problems in people of hong kong. based on a large community sample, ni et al. ( ) reported that the prevalence of probable depression was . % in which was much higher than that during - ( . %) and . % after the occupy central movement in . besides, the estimated ptsd prevalence rate was . %. mogul ( ) also pointed out that ptsd symptoms were common in the protesters. ng ( ) used the term "mental health tsunami" to describe the situation which was brought forth by the repeated and direct involvement in violent conflicts between protesters and police, exposure to violence, disintegration of families and friends, and the declining economic conditions. why the fire broke out? quality of life and well-being issues as fuels we can use "fire" to represent the social event which has lasted for roughly months. obviously, the fundamental question is why the fire broke out. in view of the highly political nature of the social movement, there are views suggesting that the event was initiated and orchestrated by forces outside hong kong. such views are primarily driven by the notion of "color revolution" which has occurred in places like tunisia and ukraine. in addition to western influences, taiwan has been suspected to play a strong role in the social movement. the reasoning is that by highlighting the message that the "one country, two systems" arrangement does not work, the president of taiwan (tsai ing wen) would get more support in the presidential election in . although these conspiracy conjectures make sense on the surface, we need empirical evidence that cannot be easily substantiated. also, conspiracy theories alone do not give full attention to the psychology of the protesters and they cannot explain the perpetual involvement of young people as well as the determination of some of them to die for the sake of producing political changes in hong kong. unfortunately, not many systematic investigations have been conducted to explore the genesis of the social movement. a pioneer paper on the protests in hong kong in was written by purbrick ( ) who argued that in addition to errors in police operations, housing, poverty, and governance are three key factors underlying the social event. in this paper, we attempt to understand the social movement from the perspective of quality of life and well-being. the main thesis is that the social unrest exists because there are threats to and issues in quality of life and well-being in hong kong. from an individual perspective, quality of life is a multi-dimensional construct. according to felce and perry ( ) , overall quality of life is a function of three factors, including objective life conditions, including physical well-being (e.g., personal safety), material wellbeing (e.g., security), social well-being (e.g., acceptance and support), emotional well-being (e.g., respect) and development and activity (e.g., choice and control), subjective feelings of the objective life conditions and personal values and aspirations. obviously, threats to quality of life in these domains would arouse fear and distress for an individual. from a societal perspective, organization for economic co-operation and development (oecd ) proposed the following indicators of human well-being: health status, work and life balance, education and skills, social connections, civic engagement and governance, environmental quality, personal security, and subjective well-being. again, threats in well-being in these domains, particularly in the areas of governance and personal security, would lead to strong reactions from people in the society. according to the ecological perspective, there are different ecological systems governing human development where individuals experience well-being (or ill-being) in different systems. these include the personal system (e.g., threat to freedom and finding life meaning through involvement in a "revolution"), interpersonal system (e.g., peer influence and bonding amongst peer protesters), family system (e.g., lack of family warmth), social system (e.g., sensational social media influence), and political system (e.g., lack of trust in the government and support for protesters from bodies outside hong kong). by examining the quality of life and well-being in different systems, we can get some clues on the related deficiencies and threats in quality of life which have shaped the development of the social event in hong kong in - . the fire triangle: fuels, heat, and oxygen according to the fire triangle, there are three basic elements of fire -fuels, heat, and oxygen. in this paper, we treat the quality of life and well-being issues as "fuels", the extradition bill as "heat", and some contextual influences (such as support from the general public for young people's involvement in protests) as "oxygen". there are ten pre-existing fuels and two new fuels for the "fire" as follows: pre-existing fuel no. : distrust in the central government hong kong had been a british colony from to june , . although hong kong physically returned to china on july , , it has been difficult for hong kong people to develop a high level of trust in the beijing government for two reasons. first, people tend to fixate on the unfortunate history of the cultural revolution and june th incident of . second, as corruption in mainland china has been a thorny problem since the opening of china in the late s, governance in china has been seen in a negative light by hong kong people. empirically, studies showed that the level of trust in the beijing government has been fluctuating with roughly . % of the respondents having no trust in the first months of (public opinion poll, the university of hong kong b). lack of trust in the central government clearly suggests political uncertainty which constitutes a threat to the political well-being of hong kong people. studies have shown that % of the young respondents regarded themselves as "hongkonger" rather than "chinese" (public opinion poll, the university of hong kong a). the weak national identity can be attributed to the vast differences in cultural and social background between hong kong and mainland china, such as views on individual freedom and governance. the negative stereotypes formed for mainland chinese people (e.g., poor hygiene and snobbishness) also constitute blocks to identify with the chinese national identity. as national identity is an important aspect of self-identity, a blurred national identity is a threat to personal well-being, which suggests a sense of rootlessness. under the british colonial rule, the governor was not elected but appointed by the british government (i.e., hong kong people had no say). until the last decade before the handover, the colonial government began to introduce some political reform initiatives. the basic law also stipulates that there would be a progressive change in the election systems of the chief executive and legislative council members. although the political system can be regarded as more "open" after , hong kong people (particularly the youngsters) are not satisfied for two reasons. first, the current political system gives heavier weight to the businessmen who have been blamed to create economic and social inequalities in hong kong. second, as the government of the sar has not been working effectively after the handover, people generally want to have more say in important decisions for hong kong. obviously, dissatisfaction with the political system is a threat to political well-being (oecd ). one related factor that should be considered is the ideals of young people. in the good old days, the formula for youth development is to motivate young people to succeed in academic study (entrance to a government-funded university and study in a professional programme), get a job with a handsome salary and establish a happy family. however, for the generation z (i.e., commonly refers to young people born in the late s and early s), they are more autonomous, technology-oriented and more concerned about social issues (dolot ; gaidhani et al. ) . in other words, putting the material good life as the "carrot" does not really work for students of generation z because material possession may not be their primary concern. pre-existing fuel no. : economic strains (poverty, high housing price and high cost of living) although hong kong enjoyed almost full employment as well as high gpd per capita in early , wealth distribution has been a persistent problem: roughly one in four adolescents grow up in poor families; the gini coefficient is disturbingly high (oxfam ); there were around . million poor people with , poor households in (government of the hong kong sar ). assuming % of the poor people were dissatisfied young people, it means around , young people were on the street protesting against the government. research has showed that poverty is a risk factor affecting the quality of family life and individual well-being, which would in turn undermine the healthy development of adolescents and cause problems such as the development of externalizing behavior. it also impairs the quality of life of the hong kong society. historically speaking, housing has been a thorny problem in hong kong. unfortunately, the problem has been much aggravated after the handover back to china. according to some surveys, the housing price in hong kong and the cost of living were the highest in the world (arcibal ) . there are three consequences of this situation. first, young people would find it difficult to get married, hence creating much frustration in youngsters. for some of the married young couples, they may be forced to stay in sub-divided flats that have security and hygiene problems. second, parents are expected to help children (as reflected in the saying of "the success of young people depends on the hard work of the father") which creates much intergenerational conflict in the family. finally, the rocket high housing price creates a sense of hopelessness in young people because it would be a heavy burden even for young professionals to buy a decent flat. the high housing price obviously triggers much negative emotions in young people. with the extradition bill, it is a good opportunity for them to air out their anger and hopelessness as well as a desire for "mutual destruction" (i.e., let us have nothing together). the high housing price is an obvious threat to physical well-being (shelter), psychological well-being (hopelessness), family well-being (conflict and tension within the family), social well-being (rich-poor divide), and political wellbeing (hatred for the government for its ineffective housing policies). although there was almost full employment in , youth employment has been an issue of concern for many years (government of the hong kong sar ). with the introduction of more self-financed sub-degree and degree programs, many graduates are not able to move up the social ladder because the real income for university graduates has been quite stagnant since the handover (new century forum and new youth forum ). again, lack of upward social mobility triggers negative emotions in young people which eventually promotes a sense of hopelessness in young people (shek and siu b) . this also explains why young people have psychological resistance to return to china because their lives have not improved much after the handover. it is also why some young people waved the british flag during demonstrations which are clearly a sign of remembering the "good old days" for university students under the british rule. obviously, the lack of opportunity for hong kong young people to have upward mobility is a serious threat to individual well-being and societal quality of life. nevertheless, young people are commonly not aware of the fact that the lack of social mobility also exists in many developed countries in the world and there was also much inequality under the british rule. under the influence of the chinese culture, hong kong emphasizes strongly on academic excellence and achievement, with success commonly defined in terms of good grades in public examinations and earning a lot of money. such social mentalities have three consequences. first, striving for academic excellence can be very stressful for young people which impairs their personal well-being. one consequence is that young people are prone to develop internalizing behavior such as depression and suicide. in fact, the appeal for "mutual destruction" can be regarded as a manifestation of mass internalizing behavior. second, the exam-oriented system naturally creates "losers" in young people. as only % of high school graduates can get governmentfunded university places, the number of "losers" created every year is quite substantial. third, it would be difficult for students to find authentic life meaning in study except "getting good grades". most of the time, young people in hong kong have "foreclosure" identity according to the psychosocial theory of erik erikson (i.e., commitment without crisis). hence, when young people face the slogan of "liberate hong kong, revolution of the time", the social movement gives them a noble and romantic life meaning which can be easily incorporated in their identity. in short, the morbid emphasis on academic excellence undermines the academic and personal well-being of students which can be easily filled by some heroic and grand ideals such as revolutionize hong kong to make the tomorrow better. young people in hong kong face many psychosocial stresses, including academic stress, low income, high property price, long working hours, and a small living environment. shek and siu ( b) argued that the developmental context for hong kong adolescents is "unhappy", including unhealthy values, de-emphasis of holistic youth development, rise in hopelessness but drop in life satisfaction, emphasis on academic excellence but de-emphasis on academic quality of life, poverty, parenting issues, and drop in family well-being. obviously, stresses and risk factors in adolescent development can easily be translated into poor mental health amongst young people. there are research findings showing that adolescent hopelessness rises but life satisfaction drops in adolescent years (shek and liang ) . at the same time, their academic stress increases but their perceived support from school decreases (shek and chai ) . in other words, the well-being of adolescents in hong kong is at risk. in the special issue edited by shek and siu ( b) , the papers show that mental health is a growing concern in young people in hong kong. there are also findings suggesting that mental health problems in university students are prevalent (lo et al. . in other words, young people with poor well-being are emotionally charged time bombs waiting to be detonated. finally, students with special educational needs may be a factor that should not be overlooked. when we examine the slogans of the protesters, it is not uncommon to see that there are many incorrectly written chinese characters. there are two possible explanationseither the protesters are poorly educated or they are dyslexic who are commonly having difficulties in writing chinese characters. it is noteworthy that students with special education needs (e.g., those with autistic features or dyslexic) are stubborn in their views. there are several disturbing developments of families in hong kong, including rising divorce and remarriage rates, rising cross-border marriages, worrying child abuse rates, growing number of parents who are not hong kong residents, growing cross-border workers, long working hours, and aging population. these problems negatively affect young people who experience family alienation and conflicts arising from unfavorable family circumstances. obviously, the social event constitutes an excellent opportunity for them to feel the warmth amongst the "comrades" and have deep sharing and mutual concerns amongst the participants who may not have such warm experience before. in other words, low family quality of life is a strong precursor for active and romantic participation in the social movement. nevertheless, there are also reports saying that some parents actually encourage their kids to actively participate in the movement, including engaging in violent behavior. although young people face many psychosocial stresses and challenges, there is weak systematic life skills education for adolescents. in many countries, social-emotional learning, soft skills and psychosocial competence, including the promotion of selfunderstanding, social understanding, interpersonal competence, responsible decision making, and self-management skills are strongly promoted. although critical thinking is emphasized in liberal studies under the new high school curriculum in hong kong, it is argued that students actually learn "criticism mentality" instead of "critical thinking". in a series of cross-sectional and longitudinal studies, showed that while different stakeholders endorsed the importance of life skills education in the formal curriculum, they perceived that life skills education in the formal curriculum was insufficient and life skills development in adolescents was incomplete. without such systematic education, the personal well-being of young people in hong kong cannot be adequately protected (shek and siu a) . the neglect of soft skills education for young people in hong kong means that they do not possess adequate social competence skills to negotiate with other people or resolve conflicts, which are much needed. as intense anger and hatred are involved in the social event, learning how to empathize (look at things from others' perspective), manage one's and others' emotion (emotional quotient), forgive (write off emotional feelings and debts), and re-conciliate (re-build new relationships and move on) are important tasks for adolescents. these life skills are very important because there are studies showing that hong kong adolescents showed narcissistic behavior (leung ) and positive youth development attributes negatively predicted the use of foul language in adolescents (shek and lin ). although there is an area on moral, civic and national education in the formal curriculum, the policy and scope of the national education curriculum are unsystematic and uncoordinated. in a study comparing related moral, character and citizenship education in chinese societies (hong kong, mainland china, and taiwan) and non-chinese societies (singapore, uk, and usa), shek and leung ( ) identified several problems in this area, including absence of comprehensive planning and policy development, blurred concepts and lack of focus on holistic student development, lack of emphasis of moral and character education, problem of "penetrative" approach, absence of formal curriculum materials, problematic operational strategies, and lack of evaluation. besides, while national education is undertaken by the education bureau (formal school curriculum), the home affairs bureau (committee on the promotion of civic education), and the labor and welfare bureau (youth section in the social welfare department), there is little coordinated effort amongst the different bureaus. the lack of related education suggests that the personal well-being of young people in terms of moral competence cannot develop in a healthy manner. obviously, there are two difficulties in implementing moral education in hong kong. the first one is "what" should be covered. if the coverage covers chinese history in the past century, students can learn more about what happened in china, particularly the exploitation under western imperialism. however, as history is multifaceted, how to interpret historical facts is a thorny issue. the second issue is "how" to assess the outcomes. while an increase in knowledge is easy to demonstrate, positive change in attitude and behavior may not be easy to assess objectively. in view of the sensitive nature of chinese history, some schools simply cut the subject under the new education reform. under these circumstances, it is not surprising to note that many young people are not familiar with modern chinese history and geography of china. the responses of the government to the protests since june have been regarded to be slow and ineffective. besides condemning violence and vandalism, the government has relied primarily on the police to deal with the protests. the attempt to have dialogues with the public also does not appear to be very successful. most important of all, although the bill has triggered such a huge social event, no senior government official steps down. this is very interesting because in similar situations in other countries, some senior government officials would have stepped down to take political responsibility. again, this reflects the threat of political well-being in governance which intensifies public worry, anger, and frustration. of course, in understanding the responses of the government, two points must be noted. first, in view of the unprecedented nature and the extent of the protests, it is not easy to handle. as pointed out by the prime minister of singapore (lee hsien loong), singapore would be "finished" if similar protests happened in singapore (sim ) . second, dissatisfaction with the government has been a common theme in protests which intensifies the protests. for example, the commission of inquiry ( ) concluded that "a recent tendencynot only in hong kongto ascribe all the failings of the community to errors by the administration and to make greater demands upon it tends not only to enhance discontent but to exaggerate their extent" (p. ). there are numerous and serious allegations that the police used excessive force, such as in the protests held on june , july and august , (purbrick ). on the other hand, the police was criticized as doing nothing when people in yuen long were attacked by those who did not support the protesters on july , . obviously, such allegations are great threats to the personal well-being of the protesters and the social well-being of hong kong. on the one hand, some videos in the news reports and the internet strongly suggest that excessive force might have been used by the police. while some of the related complaints are still under the investigation of the independent police complaints council (ipcc), the mechanism does not earn the trust of hong kong people for two reasons. first, some ipcc members were appointed by the government, which means that their independence is doubtful. second, many protesters experiencing excessive force by the police do not complain because they have the fear that they will be prosecuted for involvement in riots. on the other hand, it should be noted that "innocence before proven guilty" is the cornerstone of the common law and the establishment of police violence and brutality requires evidence beyond reasonable doubt. besides, objectivity of some videos uploaded to the internet is not clear. in addition, it would not be objective if we ignore the fact that public perceptions of the police had been very good before the social event and the hong kong police ranked very high in terms of professional service in international surveys. for example, in the human freedom index (vásquez and porčnik ) , hong kong police ranked sixth ( th) under the indicator of "reliability of police". in the legatum prosperity index ( ), hong kong police ranked fourth ( th) out of countries and regions under the indicator of "safety and security". similarly, hong kong police ranked fourth ( th) under "order and security" in the world justice project ( ). of course, having an excellent record does not necessarily mean that the alleged police issues do not exist. however, we also need expert views based on credible professionals (e.g., those who have expertise in police operations) using credible evidence from credible sources to make objective and fair judgments. there are several arrangements that create anxiety and threats for hong kong people. first, it extends the scope of extradition to cover mainland china. with the proposed changes, hong kong people who have committed certain crimes in china could be transferred to mainland china. second, there were several rounds of revisions in the process, thus giving people a sense that the whole package has not been well-conceived, and the changes were made to address the concerns of the businesspeople only. third, the proposed safeguards are considered not adequate by the public. finally, the consultation period was too short. some people queried that the consultation was too short for an issue which had not been resolved within years after the handover. at the same time, the buy-in work was not enough, and consultation was not extensive. in particular, no specific strategies were used to address the concerns of young people, particularly via social media. besides, the publicity work of the government was neither creative nor innovative. finally, the government's non-sensitivity about the public reaction to the bill greatly intensified the fear. since the proposal was published, there had been numerous reservations voiced by different sectors of the society, including businessmen, lawyers, and barristers. however, the government did not feel the pulse of the community. also, despite the fact that many people joined the protest held on june , the government still decided to move to the second reading debate on june , . such insensitivity to public reaction eventually triggered the fire. for the political fire on the extradition bill to take place, besides fuels (quality and life and well-being issues) and heat (worries that the bill had created and the public sentiment it had aroused), oxygen is a very important concern. in the social movement, several sources of wind have provided much "oxygen" for the social event. while misinformation refers to inaccurate information, disinformation refers to the deliberate dissemination of false information. in the social movement, there are numerous instances of misinformation. for example, for the number of protesters, it was claimed that there were million and million people joining the demonstrations in june . however, while it cannot be denied that many hong kong people joined the protests, the figures quoted by the organizer were doubted by cnn (mezzofiore ) . concerning the occupation of the legislative council building on july , , the police issued a warning at around : pm condemning the action of the protesters and giving the final warning for them to disperse. however, the watch of the chief superintendent had been altered to pm (wong a) in the video which suggests that the police had set a trap for the protesters. another example is the news reported by da kung pao on the assault on a legislative councilor (ho kwan yiu). while the news was released at noon on november , , the time of release was amended to be : on november , (global times ). based on the amended news, it was claimed that the assault was self-directed by ho. in the initial stage of the protests, many protesters wore surgical masks. in the late stage of the protesters, some protesters wore gas masks and covered their whole face. while it is understandable that gas masks protect the protesters from tear gas, keeping one's identity anonymous actually intensified the scale of violence and vandalism because the fear of being identified would be minimized. besides, communication in social media on protests is also anonymous, hence facilitating the planning and implementation of the protests and vandalism. as it is well-documented in social psychology that people with anonymous identity would be more likely to engage in violent behavior (zimbardo ) , anonymity has supplied much "oxygen" to the intensity and duration of the social event. many people have shown support for the protesters (particularly the students) for several reasons. first, it is commonly believed that the public should give more allowance to students who are just "kids". second, some adults have the fear that the bill would break the "firewall" between hong kong and china. third, some people believe that the students are doing what they have not done, such as a fight for democracy for hong kong. fourth, many people are angry at the slow and nonresponsive responses of the government. fifth, many people support the prevailing but toxic beliefs that "disobey the law to get justice is acceptable" and "violence is sometimes necessary under certain circumstances". finally, many people believe that violence of the protesters is justified because police have used excessive force and there is police brutality. there is also public support in terms of finance. for example, around hk$ million (us$ million) related to the sparkle alliance was frozen by the police (mok et al. ) . the public's support for the protesters (including many professional associations) and not "cutting the mattress" with the violent protesters is definitely a strong reinforcement for the protesters. in the social event, many foreign political leaders have shown support for the protesters. unfortunately, very few of them touch upon the issues of violence and vandalism. such supportive gestures have created the false impression that the movement (including violence and vandalism) is reasonable, sacred and just. material support from taiwan in the form of gas masks was also reported (sui ) . it is apparent that there are many deep-seated quality of life issues behind the social movement. as such, the solution lies in properly addressing these quality of life threats and issues. primarily, it is important to cut or eliminate the pre-existing fuels as follows: . trust in the beijing government: it is important to build up trust in the beijing central government. in social psychological literature, the contact hypothesis suggests that contact is very important to reduce prejudice (pettigrew and tropp ) . hence, increased contact to understand mainland china will be helpful. looking at the bright and dark sides of china (as these two aspects exist in all countries) and appreciating the progress of china in the past four decades such as poverty alleviation for around million people according to the world bank (he ) and acknowledgment of social problems (such as corruption) would be important. . nurturance of chinese national identity: it takes time to nurture because one has to "fall in love" and take pride in being chinese. systematic education at the community, family, and school contexts are indispensable so that young people can develop a sense of shared identity which further strengthens their positive identity. . political well-being: this is tough because the change in the political system will not take place overnight. in addition, as hong kong is an international financial center, it is not easy to reduce the influence of business corporations and related interest groups. however, given the recent overwhelming victory of the pan-democratic camp in the district council election in november , young people who wish to change can still play an active role in the future legislative council and the chief executive elections. in any case, everybody has to learn that in an open and civilized society, we have to respect the views of the majority. . poverty alleviation and solving the housing problem: it is a high time to re-visit the issue of poverty in hong kong which also exists in many countries in the world. besides the work of the commission on poverty, every sector has to rethink about their role. in addition to financial capital, building human capital, family capital and social capital is also important to strengthen the developmental assets of poor adolescents, which can help them escape from the trap of intergenerational poverty. as housing implies physical security which shapes hope, this is the top priority issue to be addressed. . upward mobility: this is not easy to solve this issue because it is a global issue that is not specific to hong kong. however, as many young people do not want to join the manual labor force which can give a reasonable salary, there is a need to change the community culture to one that treasures different talents (i.e., not just scholastic skills) and there are different career paths for young people with different aspirations, interests, and skills. . education reform: there is a need to deeply reflect on the purpose and nature of education so that young people can study for their interests (i.e., not just for the "rice bowl") and multiple intelligences are emphasized. the challenge is not just for the government, but also for parents and the hong kong society. . promotion of adolescent well-being: relevant and adequate services should be provided for young people who need mental health services. a public health approach focusing on universal, selective and indicated prevention should be used. in particular, services for students with special education needs should be stepped up. besides, finding ways to promote hope and life satisfaction is also a priority task. in addition to changing the macro-environmental factors leading to hopelessness, evidence-based programs to cultivate resilience and hope in young people, such as the project p.a.t.h.s. (shek and sun ; ma et al. ) are indispensable. . promotion of family well-being: problem families are the ideal breeding grounds for adolescent externalizing behavior. hence, there is a need to promote family resilience in a high-risk environment and to strengthen parenting, communication as well as conflict resolution skills in the family. it is noteworthy that evidencebased programs on promotion of family resilience are almost non-existent in hong kong. . promotion of life skills education: in the absence of systematic life skills, socialemotional learning skills, and psychosocial competencies training in the formal education curriculum in hong kong, this gap should be urgently addressed (shek and siu a) . young people should learn that: a) "an eye for an eye makes the whole world blind"; b) the essence of democracy is respecting the views of everyone, including those who do not hold the same views; c) it is morally wrong to blackmail the government by kidnapping the innocent public; d) besides rights and social justice, there are other virtues, including love, acceptance, and forgiveness, that are equally important; and e) while one can "criticize" the government, one should also look at things from different perspectives in a "critical" manner. . development and implementation of systematic moral and national education: one unfortunate observation of the social movement is that there is much hatred and deep erosion of the spirit of rule of law (such as widespread use of "doxing" and even physical violence in dealing with those who hold different views). as conflict resolution and mutual respect are not adequately covered in the current moral and national education curriculum, there is an urgent need to review and step up the related policies in hong kong. when implemented, policymakers should be aware of the related fears, such as the worry of brainwashing the young people. as such, practices in other countries can serve as the reference point because "international standards" will be used. regarding the "heat", there are many learning points for the government to reflect, particularly on its efficiency and responses in the whole social movement. for example, sufficient consultation time should be given to sensitive issues like the extradition bill. concerning the influence of social media, there is no way to stop it unless we follow what the spanish government did to deal with the occupation of the airport. however, the public can learn how to critically differentiate correct information, misinformation, and disinformation, particularly information disseminated and acquired through the social media. for anonymity, while it is a protection for not being arrested, people wearing masks should understand that anonymity would unleash the dark side of human nature. concerning public endorsement of violence, several questions should be considered by the public: a) what is the "civilized" and "mature" form of public demonstration? b) assuming the police has used excessive force, is vandalism the best response (i.e., "an eye for an eye")? c) how can we promote peaceful co-existence within diversity in political views? these are obvious quality of life issues awaiting answers. regarding alleged police violence brutality, there is a social consensus on setting up an independent panel of inquiry. however, to be fair to the police and protesters, if an independent panel of inquiry is established, it should examine violence and excessive use of force in both the protesters and police. finally, a critical understanding of the comments made by foreign governments and parties should be realizedwhether they are genuine concerns about hong kong or disguised manifestations of political and/or national interest. in conclusion, pre-existing and new quality of life and well-being threats and issues have shaped the development of the social event in the past months in hong kong. without understanding quality of life issues in different ecological systems (such as fear about losing freedom, lack of political well-being, growing up in a poor environment, always being a loser, living without hope, inability to forgive and re-build), it would not be possible to find workable and meaningful solutions. once again, the case of hong kong demonstrates that economic development alone is not enough to promote human well-being in a society. in the report of the commission of inquiry ( ) reviewing the riots, it was concluded that "we do not believe that political, economic and social frustrations were the direct cause of the riots but within the economic and social fields there are factors, to which we have drawn attention and that need to be watched, lest they provide inflammable material which would erupt into disturbance should opportunity arise in the future" (p. ). after some years, it is interesting to note that some of the deep-seated quality of life and well-being issues, such as inadequate housing, over-crowding, and limited chances in life come into the scene again. the only major difference is that many educated young people are involved in the social event in - , in contrast to the predominance of poorly educated young people in the riots. hong kong tops global list of most expensive housing market again as protests make little dent tourist arrivals take sharpest plunge in november since protests began in hong kong hong kong's protesters are trying to break free from the "old seafood" generation a perspective based on quality kowloon disturbances : report of commission of inquiry the characteristic of generation z. e-mentors quality of life: its definition and measurement understanding the attitude of generation z towards workplace government of the hong kong sar china's subsidies lifting rural villages out of poverty, but is xi jinping's plan sustainable? the legatum prosperity index: a tool for transformation hong kong kids more narcissistic than western kids according to cityu study common mental health challenges in a university context in hong kong: a study based on a review of medical records. applied research in quality of life an innovative multidisciplinary healthcare model in student mental health: experience in hong kong. applied research in quality of life changes in the participants in a community-based positive youth development program in hong kong: objective outcome evaluation using a one-group pretest-posttest design that viral photo of the hong kong protests is not what it seems ptsd and protests: how the violence on hong kong's streets impacts mental health police freeze hk$ million raised by spark alliance for hong kong protesters, with group suspected of using money for personal gain and rewards. south china morning post a comparative study on the income of different generations of university graduates in hong kong mental health crisis in hong kong: its current status and collective responses from mental health professionals in hong kong depression and post-traumatic stress during major social unrest in hong kong: a -year prospective cohort study oecd better life initiative: compendium of oecd well-being indicators hong kong inequality report allport's intergroup contact hypothesis: its history and influence ethnic identity -chinese (per poll people's trust in the beijing central government ( - / - - a report of the hong kong protests commissioner of the hk police the impact of positive youth development attributes and life satisfaction on academic well-being: a longitudinal mediation study a study on the development of chinese students (character psychosocial factors influencing individual well-being in chinese adolescents in hong kong: a six-year longitudinal study use of foul language among chinese adolescents: developmental change and relations with psychosocial competences adolescent mental health policy and services in hong kong: seven unresolved problems waiting for solutions unhappy" environment for adolescent development in hong kong [special issue development and evaluation of positive adolescent training through holistic social programs perceptions of adolescents, teachers and parents of life skills education and life skills in high school students in hong kong singapore's lee hsien loong a social media hero in china for hong kong protest comments hong kong protests: the taiwanese sending , gas masks nearly a fifth of hong kong voters say they support violent actions by protesters, such as attacking opponents or hurling petrol bombs and bricks fugitive offenders and mutual legal assistance in criminal matters legislation (amendment) bill legal service division report on fugitive offenders and mutual legal assistance in criminal matters legislation (amendment) bill united nations development programme the human freedom index hong kong extradition bill: police deny rumours of pre-recording july condemnation video and issue clarification hong kong protests: what are the "five demands"? what do protesters want? youngpost hk$ million bill for repairs on public facilities vandalised by antigovernment protesters the human choice: individuation, reason, and order versus deindividuation, impulse, and chaos publisher's note springer nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations acknowledgements the preparation for this editorial is financially supported by wofoo foundation and tin ka ping foundation. address all correspondence to daniel t.l. shek, department of applied social sciences, the hong kong polytechnic university (daniel.shek@polyu.edu.hk).open access this article is licensed under a creative commons attribution . international license, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the creative commons licence, and indicate if changes were made. the images or other third party material in this article are included in the article's creative commons licence, unless indicated otherwise in a credit line to the material. if material is not included in the article's creative commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. to view a copy of this licence, visit http://creativecommons.org/licenses/by/ . /. key: cord- -lxqcvqca authors: rao, nirmala title: sars, preschool routines and children’s behaviour: observations from preschools in hong kong date: journal: int j early child doi: . /bf sha: doc_id: cord_uid: lxqcvqca all schools in hong kong were closed in april to prevent the spread of sars. this paper considers the influence of the sars epidemic on children’s routines and behaviour when preschools re-opened, after a six-week closure. observations were made in kindergartens and principals of another kindergartens completed questionnaires. the influence of sars was evident in all preschools, be it through teachers and students wearing masks, notices on hand washing or the provision of alcohol dispensers for hand disinfection. the outbreak impacted noticeably upon children’s routines and social exchanges. in all schools, physical contact among children and sharing of food were not allowed. children were also prohibited from talking to their peers when they had removed their masks. the sars outbreak provided us a “natural experiment” to consider the influence of epidemics on preschools. las manos o se instaló una gran cantidad de dispensadores con alcohol para desinfectarse las manos. el brote y las medidas de prevención, afectaron en forma perceptible la rutina y el intercambio social de los niños. en todas las escuelas, se prohibió el contacto físico entre los pequeños, los que tampoco podían compartir alimentos. además, a los niños no les estaba permitido hablar con sus pares si se habían quitado la máscara. el brote de sars nos proporcionó un "experimento natural" para analizar la influencia de las epidemias en los establecimientos preescolares. during the past years, there have been five killer viruses, including the spanish flu ( ) , the asian flu ( ), the hong kong flu ( ), severe acute respiratory syndrome (sars) ( ) and the avian flu ( ) (dunne, ) . flu pandemics have led to the closure of schools as it is assumed that infectious diseases can be rapidly transmitted in school premises. previous research indicates that school closure reduces the incidence of viral respiratory diseases among children during an influenza outbreak (heymann, chodick, reichman, kokia & laufer, ) . it has been suggested that one of the reasons that hong kong flu ( ) was less deadly than the spanish and asian influenzas is that it peaked during the school holidays and children did not spread the virus in school. research also indicates that upper respiratory infections (uris) are much more common in preschool children in centre-based care than those who are looked after at home (nichd eccrn, ) . hence, medical research indicates that preschool closure prevents the spread of viral respiratory diseases and that children in centre-based care are more susceptible to uris. on the other hand, because of the nature of transmission mechanisms, there is an extremely small likelihood that viruses like hiv/aids will be spread in preschools. schools were closed in britain and the united states during the spanish flu (billings, ) . more recently, in , schools were closed in canada, mainland china, singapore and hong kong to prevent the spread of sars. five schools were closed in ontario, canada (health canada, ) . on the other hand, there were mass school closures in asia. in singapore, all schools were closed on march and re-opened in phases after april (singapore government, ) , and in hong kong, schools were closed for at least weeks and also re-opened in phases with secondary schools re-opening before primary schools. preschools in hong kong were officially closed between march and may , . appendix provides the who report on the course of the sars outbreak in hong kong. there were a total of , sars cases in hong kong and deaths occurred because of sars (government of hong kong, ) . it should be noted that there were many unknowns about the transmission of sars at the height of the outbreak. the high population density of hong kong puts her at risk for the rapid spread of infectious diseases. further, since hong kong is used as a gateway between mainland china and the rest of the world, control of the epidemic was a top priority for the hong kong government. in hong kong, preschool institutions are in the private sector. they include child-care centres which serve children from weeks to years and kindergartens which enrol children ranging in age from years months to years. most kindergartens offer bi-sessional classes of around three hours each, while most child care centres offer whole-day programs. about % of children over years of age in hong kong attend preschool programmes. the extent of coverage reflects both government policy and the value that chinese parents traditionally attach to early childhood education. the government determines, monitors, and enforces standards for preschools. adult-child ratios are currently about : in kindergartens and curriculum guidelines are issued by the government. the guide to preprimary curriculum advocates a child-centred approach and stresses all-round development (government of hong kong, ) . it espouses contemporary views on effective early teaching and learning, and provides suggestions for facilitating intellectual, communicative, personal, physical and aesthetic development. the hong kong government was concerned that some kindergartens went too far in presenting formal academic curricula, using inappropriate teaching methods for children below the age of six. hence, in , a list of 'dos and don'ts' for kindergartens was published (government of hong kong, ) . the list of 'dos' includes having a curriculum that covers moral, cognitive, physical, social, and aesthetic aspects of development by organizing activities that promote all-round development; organizing various child-centred learning activities; using the mother tongue as the language of instruction, and respecting individual differences. good programs in any country achieve all these goals, but some are especially pertinent to hong kong idiosyncrasies. for example, chinese culture emphasizes moral development, and it is recommended that the curriculum attends to this perspective. as in other societies, pedagogical practices in hong kong preschools are influenced by cultural beliefs about early learning. in the past, the chinese teacher was characterised as a fountain of knowledge who force-fed peking ducks. however, children spend more time in play-based learning now than in the past and there has been a corresponding decrease in expository teaching. it appears that traditional chinese cultural beliefs about early learning have taken a back seat to what is considered as good educational practice. cultural beliefs about childhood and education also influence pedagogy. for example, kindergartens tend to have highly structured days. this is partly due to children's age, but also a reflection of chinese cultural beliefs about the early years being a time for training young children to be disciplined and behave properly (rao, mchale & pearson, ) . during visits to preschools when they re-opened after the mandatory closure, the author was struck by the marked changes in preschool routines. hence this study was undertaken to provide an objective documentation of these changes. the main objectives of the study were to (i) consider the influence of the sars epidemic on children's routines and behaviour when preschools reopened after a six-week closure; and (ii) consider principals' perspectives on the lessons that had been learned about promoting children's learning and managing preschools during an epidemic. a retrospective study was conducted. the sample, although not randomly selected, was representative of hong kong preschools in terms of location, sponsor, status, size, and tuition fees. surveys were completed by observers in preschools ( kindergartens and child care centres), and principals in another preschools completed questionnaires. survey completed by observers. items on the survey fell into categories including: information about the preschool and children ( questions); routines before the sars outbreak ( questions); learning during school closure ( questions); preparing the kindergarten for re-opening ( questions); students return to kindergartens ( questions); lessons from sars ( questions); and demographic information about the observers. the items on students' return to kindergartens included questions on daily routines ( questions); health issues ( questions); social interaction among children ( questions); preschool management ( questions); and school holidays ( questions). the majority of questions required responses in a fixed choice format. examples of items are presented in the appendix. questionnaires were completed by principals of kindergartens. these addressed similar categories as those in the survey given to the observers but reflected their different perspectives and access to information. the questions to principals included ones on: learning during school closure ( questions); preparing the kindergarten for re-opening ( questions); students return to kindergartens ( questions); and lessons from sars ( questions). we were particularly interested in gathering information from principals about learning during preschool closure. this is because schools in hong kong and mainland china took particular advantage of the information and communication technology available to ensure that learning could take place even though schools were closed. the questions on "learning during school closure" included those related to: decisions about when to close and re-open the school ( questions); teaching and learning ( questions); contacting students ( questions); homework ( questions); and computer-supported learning ( questions). government guidelines and regulations for preschools issued between march and may were perused. the survey for observers and the questionnaire for principals were developed in english and the observers, all of whom were completely bi-lingual (english-chinese), completed the english version of the survey. the questionnaire for principals was translated into chinese and a back-translation procedure was used to ensure accuracy of the translation. principals completed chinese versions of the questionnaire. surveys of preschools ( kindergartens and child-care centres) were conducted by experienced lecturers, who were responsible for the practicum supervision of students in early childhood teacher education programmes. they were given training in the use of the survey, in which to record their observations and they consulted with the student-teacher they were supervising in completing the survey. surveys were conducted within a month of preschools' re-opening. questionnaires were distributed to principals in july and returned by late august. the aim of this study was to document the influence of the sars epidemic on children's routines and behaviour, and consider principals' perspectives on promoting children's learning and managing preschools during an epidemic. in the following section, information garnered from the survey is presented under the following headings: school closure; learning during school closure; school re-opening; changes in routines; change in curriculum/pedagogy; and changes in social interactions. principals' perspectives are presented in the last section. as noted earlier, preschools were officially closed between march and may , . however, % of the preschools closed before that date. the majority of preschools re-opened on may , . teachers in all schools contacted students at least once per week during school closure and % of teachers contacted children twice a week or more often. the mode of contact varied from telephone calls ( preschools), circulars ( preschools) and e-mail ( preschools). in the preschools which were observed, a variety of assignments were distributed for home-based learning. these included worksheets ( preschools); exercise books ( schools); reading assignments ( schools); suggested parent-child activities ( schools); cd roms for demonstrated teaching ( preschools); and suggested websites for home learning ( preschools). according to the observers, many changes were apparent in the school environment when children returned to preschool. all schools had visual displays about hygiene and the preschool environment was much cleaner. disinfection kits were located in most rooms. further, in many schools, teachers wore aprons to hold alcohol spray and extra masks. observers reported that % of the preschools instituted a moderate change in routine. in keeping with government guidelines, children's temperature was measured when they came to preschools and they washed their hands several times a day. in % of the preschools, there was a drastic change in routines, including a shortening of the length of school day. free play was curtailed and snack time was cancelled in some schools. in schools where it was continued, children had to face the wall while eating their snack. physical education (p.e.) and music lessons were cancelled and group size decreased in all schools. a specific example of a change in routine comes from the requirements for children when they entered preschool. in several preschools, children stepped on the disinfection mat outside the main door of the preschool and had their temperature and hands checked. they then had to remove their shoes and wash their hands. in fact, in some schools children had to wash hands up to times within a -hour period. during the sars outbreak, the education and manpower bureau of the hong kong government issued a curriculum for children ranging in age from - years. this included the following independent lessons: learning about sars; personal hygiene ( ); personal hygiene ( ); concern and respect for a sars patient; sars symptoms, wearing masks and washing hands; learning to prevent sars. in all preschools, the curriculum was modified to include sars education. all preschools talked about protection from sars, proper washing of hands, not touching face, and not sharing food. there was a decrease in instructional time in all preschools. some preschools introduced new themes and did not address previously planned themes. activities and games to raise awareness about the prevention of sars and the importance of personal hygiene were included in some schools. observations indicated that some schools accelerated teaching in order to "finish" all themes. teachers typically did not initiate activities such as circletime or story-telling with the whole class. instead more activities were conducted with small groups of children and there was more small group teaching. the latter is considered more developmentally and pedagogically appropriate in the early years (bredekamp & copple, ) . the sars outbreak influenced interactions between the teacher and children and those among children. children and teachers could not see each others' facial expressions because of masks and both children and teachers experienced discomfort when talking while wearing masks. there was also a reduction in social interaction among peers. sharing of toys was prohibited. children were given individual toy packs in some schools and toys/equipment were sterilized every time they were used. it should be noted that physical contact among children was prohibited. this was a function of the government guidelines which specified that physical contact among children should be discouraged. observations revealed that in % of the preschools, desks were moved into rows and children had to face the wall during snack time. there were fewer opportunities to interact in large groups as group sizes were reduced. for example, there was less interactive teaching and opportunities for learning in groups. school activities were affected by sars. field trips were cancelled and outdoor play was suspended or restricted to small groups. observers brought back photographs from the preschools which they visited. all children were wearing masks, and children had individual "stationery" and "toy" kits as sharing was prohibited. in some preschools, teachers wore aprons with pockets which contained alcohol spray, tissues and gloves. as mentioned earlier the education and manpower bureau of the hong kong government developed a programme for preschool children on sars. this was disseminated to all preschools. reports indicate that about per cent of parents refused to pay preschool fees during the school closure. this, coupled with the decrease in demand for preschool education in hong kong because of the falling birth rate, caused financial hardship to many kindergartens. the permanent secretary of education and manpower urged property owners to reduce rents for kindergartens and child care centres, and in an open letter to parents of preschool children, pleaded with them to pay the school fees. the letters to parents were sent out on april and may , . some principals felt that that the government's response to the sars outbreak was too slow. they believed that the decision about mandatory school closure came too late and some preschools had closed before that date. interactions among adults were affected and this possibly indirectly affected children. principals reported that there was more staff teambuilding and better communication between the school and parents. one principal reported that since many social activities were cancelled, preschool children had the opportunity to spend more time at home with their families. they also felt that children developed an awareness of news and community events. by september , preschools appeared to revert to their previous routines. however, the government continued to issue circulars on preventing the resurgence of sars. the aim of this study was to objectively document changes in preschool routines as a result of the sars outbreak in hong kong. some of the changes are similar to those made in singapore when it was confronted with a potential epidemic. for example, the singapore government ( ) issued the following guidelines to keep kindergartens sars free: clean and disinfect kindergarten premises; educate children, teachers and parents on precautionary measures against sars; daily temperature screening procedures for all children; and children who had travelled to sars-infected areas had to stay away from kindergartens for days after their return to singapore. others changes in routines in hong kong preschools are a reflection of their specific circumstances and broader chinese beliefs of learning. all schools were closed during the mandatory period while some closed even before this. the latter reflects the autonomy given to preschools. preschool education in hong kong is not part of the main compulsory education system although over per cent of children ranging in age from to years are enrolled in some form of preschool education (wong & rao, ) . the government does, however, ensure and monitor standards of service and through a fee remission scheme, the government seeks to ensure that no child is deprived of early childhood education because of its financial reasons (rao, koong, kwong & wong, ) . preschools prepared a variety of assignments for children during school closure. eighteen out of preschools which were observed distributed worksheets while others sent exercises and reading assignments home. some preschools burnt cds so children could watch their teacher's instruction. summer holidays were also curtailed so children could "make-up" for missed classes. the provision of assignments and the longer school year reflect the relatively high academic focus prevalent in kindergartens in hong kong and the emphasis placed on completing the syllabus prescribed by the preschool. there were fairly marked changes in children's routines. while all would agree that children's temperature should have been taken before they came to school and they should wash their hands soon after they get there, the drastic changes in some of the routines may be considered excessive. was it necessary for children to wash hands times within hours? did preschool teachers really need to wear aprons with carry alcohol spray, tissues and gloves? did children really need to face the wall while eating their snack? however, these behaviours must be considered in the light of the general context. at the time of the sars outbreak, there were many unknowns about the transmission of sars, and there was panic in the general population. hong kong's typically crowded streets were less so, and about % of the population was wearing surgical masks. a -year-old boy played a prank on the internet and indicated that the territory was going to be quarantined. this led to panic buying and supermarkets ran out of basic supplies. it is also important to re-iterate that hong kong is a very densely populated city and this can lead to fairly rapid transmission of viruses. all preschools modified their curriculum to include education about sars and the government should be credited for the speed at which it prepared curriculum guides and materials for preschools. however, the emphasis on early pre-academic skills evident in some preschools in hong kong is reflected in the fact that some preschools accelerated their teaching in order to finish their syllabus/themes. further all local schools delayed the summer holidays by at least two weeks to make up for the school closure. on the other hand, nearly all international schools in hong kong closed on schedule for the summer holidays. one of the most dramatic changes noticeable was the decrease in social interaction among children. children experienced discomfort when talking while wearing a mask and teachers and students could not read each others' facial expressions because of the masks. children's desks were moved into rows and they were not allowed to change seats during the day. group size was decreased and there was less interactive teaching. there was an increase in solitary play and children were not allowed to share toys and physical contact among children was prohibited. all the changes in social interaction reflected government guidelines. in conclusion, the hong kong government acted efficiently and effectively during the period of school closure. guidelines on the preschool environment were issued, and curriculum materials relevant to sars were available to schools before they re-opened. however, some principals felt that the decision to close schools was made too late. there were moderate to drastic changes in children's routines when preschools re-opened after the closure. sars led to modifications in school activities, and all extra-curricular activities such as school trips were cancelled. there was, not surprisingly, an increased awareness about sars and how to prevent it as a result of visual displays and curriculum changes. there was more small-group teaching and less social interaction among children. in hindsight, we can consider whether some of the changes which resulted in decreased social interaction among children were really necessary. however, it is clear that preschool educators were very resourceful and tried to ensure that the suspension of school did not mean the suspension of learning. …."sars was first carried out of southern china into hong kong, and then on to hanoi, toronto, and singapore in late february. some visitors and guests to the ninth floor of a hong kong hotel became infected through contact, in ways that remain mysterious, with a symptomatic medical doctor from guangdong province, who stayed in the hotel's room . the index case for hong kong's first outbreak, in the prince of wales hospital, visited an acquaintance staying on the same floor during the critical days in february. additional clusters were also subsequently linked to the hotel. sars had not yet been identified as a dangerous new disease when the outbreak hit hong kong's hospitals. doctors and nurses, unaware of the need to isolate patients and protect themselves, became the first victims as they struggled to save lives. in a particularly unfortunate incident, the index patient at prince of wales, admitted on march, was treated four times daily with a jet nebulizer, which probably aerosolized the virus and greatly increased opportunities for spread. in late march, hong kong suffered a major setback when a large cluster, eventually numbering more than , of almost simultaneous new cases was traced to a single building in the amoy gardens housing state. that event, which raised the possibility of an environmental source of infection or even airborne spread of the virus, was investigated by teams of local specialists. the outbreak was attributed to an "unlucky" convergence of environmental conditions that allowed the contamination of vertically-linked apartments. this conclusion, subsequently confirmed by additional studies, calmed fears that the sars virus might be airborne. from the day when the first cluster of cases was recognized, hong kong officials have provided open, honest, and abundant information about sars to both the public and the media. hong kong also benefited from the contribution of its outstanding scientists, epidemiologists, and clinicians, who were at the forefront of efforts to track down source cases in the various clusters, identify the causative agent, develop diagnostic tests, and work out treatment protocols. faced with the largest outbreak outside mainland china, hong kong also pioneered many of the control measures used to successfully contain smaller outbreaks elsewhere. it is gratifying that these measures have now brought hong kong to the point of victory over the virus, although continued vigilance remains vital. on april, who advised the public to consider postponing all but essential travel to hong kong. that recommendation was removed more than weeks later, on may". source: world health organization (june , ) update -hong kong removed from list of areas with local transmission http://www.who.int/csr/don/ _ _ /en/ the influenza pandemic of developmentally appropriate practice in early childhood programs (rev guide to the pre-primary curriculum list of dos and don'ts for kindergartens. schools curriculum circular no. / . government of hong kong, education department: government printer. government of hong kong learning from sars: renewal of public health in canada. government of canada: health canada (publication number: ) influence of school closure on the incidence of viral respiratory diseases among children and on health care utilization child care and common communicable illnesses enhancing preschool education in hong kong predictors of preschool process quality in a chinese context. early childhood research quarterly links between socialization goals and child-rearing practices in chinese and indian mothers preschool education thanks are expressed to ms. maggie koong for her help in all stages of the project and to dr. emma pearson. portions of this paper were presented at the omep world conference ( ), kusadasi, turkey and the meeting of the international society for the study of behavioral development ( ) in ghent, belgium. key: cord- -r qhfsj authors: tomlinson, brian; cockram, clive title: sars: experience at prince of wales hospital, hong kong date: - - journal: lancet doi: . /s - ( ) - sha: doc_id: cord_uid: r qhfsj nan the lancet • vol • may , • www.thelancet.com commentary the prince of wales hospital (pwh) has been at the forefront of the outbreak of severe acute respiratory syndrome (sars) in hong kong. we relate our experience at this hospital. a working definition of sars is important, although clinical conditions rarely remain within artificial boundaries. some patients might not have all features, others may present unusually. fever is a cardinal symptom but not always so, and is sometimes absent in elderly patients. some patients have presented with diarrhoea or, in at least two cases, with severe acute abdominal pain requiring exploratory laparotomy. all these patients developed typical sars. patients presenting with other respiratory infections must now all be regarded as potential sars cases until proven otherwise. contact with a known case is an important discriminator but, if emphasised too strongly in the diagnostic process, may lead to false positives or negatives. the difficulty of making a firm diagnosis until chest radiographic changes appear has important implications for health-care personnel and for surveillance. three major reasons for spread of infection to health-care workers have been: failure to apply isolation precautions to cases not yet identified as sars, breaches of procedure, and inadequate precautions. every patient must now be assumed to have sars, which has major long-term implications for the health-care system. another reason for spread among health-care workers is infected workers continuing to work despite symptoms, such as mild fever. such individuals must now cease working. however, staying at home can also have disastrous consequences for exposed family members. potential cases therefore require early isolation from both workplace and household. extreme measures are required to protect health-care workers, who account for about % of cases. early diagnosis by virus isolation or serological testing is essential to halt the spread of sars. progress has been made with the isolation of the coronavirus. [ ] [ ] [ ] a metapneumovirus was also identified in canada and in many of the cases at pwh. coronavirus appears to be the main pathogen, but dual infections may be possible. such situations are uncommon in human disease, apart from hiv-related infections, but in veterinary medicine combined infections with coronavirus and other agents have been described. , the first cases probably occurred in guangdong province in southern china in november, . the term sars appears to have been first used for a patient in hanoi who became ill on feb , , and was evacuated back to hong kong where he died on march . the physician who raised the alarm in hanoi, carlo urbani, subsequently contracted sars and died. the first case in hanoi had stayed at a hotel in kowloon, hong kong, at the same time as a -yearold doctor who had been treating pneumonia cases in southern china. this doctor was admitted to hospital on feb , and died from respiratory failure soon afterwards. he was the first known case of sars in hong kong and appears to have been the source of infection for most if not all cases in hong kong as well as the cohorts in canada, vietnam, singapore, usa, and ireland, and subsequently thailand and germany. the index patient at pwh was admitted on march , , and had also visited this hotel. he had pneumonia which progressed initially despite antibiotics, but after days he improved without additional treatment. on march , health-care workers at pwh were ill and potential cases among staff were identified later that day. further staff, patients, and visitors became ill over the next few days and there was subsequent spread to their contacts. by march , patients had been admitted to pwh with sars, all traceable to this index case. one important factor in the extensive dissemination of infection appears to have been the use of nebulised bronchodilator, which increased the droplet load surrounding the patient. overcrowding in the hospital ward and an outdated ventilation system may also have contributed. the second major epicentre in hong kong, accounting for over cases, has been an apartment block called amoy gardens. the source has been attributed to a patient with renal failure receiving haemodialysis at pwh who stayed with his brother at amoy gardens. he had diarrhoea, and infection may have spread to other residents by a leaking sewage drain allowing an aerosol of virus-containing material to escape into the narrow lightwell between the buildings and spread in rising air-currents. sewage also backflowed into bathroom floor drains in some apartments. spread to people in nearby buildings also occurred, probably by person-to-person contact and contamination of public installations. although the rapid spread of the disease in some situations may have been explained, many uncertainties remain. why the disease spread in the kowloon hotel has not been clarified, and there are many other important issues. "super-spreaders" may be prone to carry a high viral load because of defects in their commentary sars: experience at prince of wales hospital, hong kong immune system, as could be the case in the patient with end-stage renal failure implicated in the amoy gardens outbreak and another with renal failure at the centre of an outbreak in singapore. subclinical infections may also occur and will not be recognisable until reliable diagnostic tests are available. procedures causing high risk to medical personnel include nasopharyngeal aspiration, bronchoscopy, endotracheal intubation, airway suction, cardiopulmonary resuscitation, and non-invasive ventilation procedures. cleaning the patient and the bedding after faecal incontinence also appears to be a high-risk procedure. treatments have been empirical. initial patients were given broad-spectrum antibiotics but, after failing to respond for days, were given ribavirin and corticosteroids. patients who continued to deteriorate with progression of chest radiographic changes or oxygen desaturation, or both, were given pulsed methylprednisolone. steroids were used on the rationale that progression of the pulmonary disease may be mediated by the host inflammatory response, similar to that seen in acute respiratory distress syndrome, and produced by a cytokine or chemokine "storm". the clinical impression is that pulsed steroids sometimes produce a dramatic response. however, apparent benefits of steroid treatment have proven to be incorrect before, as in infection with respiratory syncytial virus. lack of knowledge of sars' natural history adds to the difficulty of determining the effectiveness of therapy. some patients have a protracted clinical course with potential for relapses continuing into the second or third week, or beyond. long hospital stays, even in less ill patients, are required, and the high proportion of patients requiring lengthy intensive care, with or without ventilation ( % in the cases from pwh ), and the susceptibility of health-care workers bodes ill for the ability of health-care systems to cope. even when the acute illness has run its course, unknowns remain. continued viral shedding and the possible development of long-term sequelae, such as pulmonary fibrosis or late post-viral complications, means that patients will require careful surveillance. this commentary is dedicated to the frontline health-care staff who have shown courageous devotion to duty throughout this epidemic. department of medicine and therapeutics, chinese university of hong kong, prince of wales hospital, hong kong sar, people's republic of china (e-mail: btomlinson@cuhk.edu.hk) world health organization. case definitions for surveillance of severe acute respiratory syndrome (sars) centers for disease control and prevention. cdc lab analysis suggests new coronavirus may cause sars identification of severe acute respiratory syndrome in canada coronavirus as a possible cause of severe acute respiratory syndrome coronavirus and pasteurella infections in bovine shipping fever pneumonia and evans' criteria for causation viral agents associated with poultry enteritis and mortality syndrome: the role of a small round virus and a turkey coronavirus severe acute respiratory syndrome (sars): multi-country outbreak-update a cluster of cases of severe acute respiratory syndrome in hong kong cdc update: outbreak of severe acute respiratory syndrome-worldwide main findings of an investigation into the outbreak of severe acute respiratory syndrome at amoy gardens a randomized, double-blind, placebo-controlled trial of dexamethasone in severe respiratory syncytial virus (rsv) infection: effects on rsv quantity and clinical outcome the dietary fibre debate: more food for thought this issue of the lancet contains two important papers that associate high intake of dietary fibre with a decreased risk of either colonic adenomas or colorectal cancer. the usa-based study done by the prostate, lung, colorectal, and ovarian cancer screening project team (plco) compared the dietary fibre intake of people who on sigmoidoscopy showed no polyps with people who had at least one histologically-verified adenoma in the distal large bowel. the study involved ten different us centres, with very different dietary practices. the european prospective investigation into cancer and nutrition (epic) consortium used a different approach to reach the same conclusion. they prospectively examined the dietary-fibre intake and incidence of colon cancer in people recruited from ten european countries. the findings of both research teams contrast with those of at least three other studies that have been published in the past years, - all of which found no protective effect of dietary-fibre intake on the development of either colonic adenomas or colorectal cancer. the new results give fresh impetus to fundamental research to determine the reasons for the protective action of dietary fibre, or to establish the definitive clinical trial.the us nurses health study was based on numbers of cases of colorectal cancer as large as in epic, and had a considerable impact on thinking. after its publication, doubts were expressed not only about population recommendations for health but even about the need for continued research. for example, santani-rim and dashwood posed the question about whether it was "time to discontinue antigenotoxicity studies of dietary fibre". of equal concern was the downturn in interest of commercial food companies to do applied research in such areas as high-fibre food products.why did these two groups of studies give such different results? although this question is obviously important, it is very difficult to answer. random variation is unlikely, given the numbers in the population groups involved. conflicting studies would be more difficult to explain if dietary fibre was a well- key: cord- - qs w xh authors: kwok, w. c.; wong, c. k.; ma, t. f.; ho, k. w.; fan, w. t. l.; chan, k. p. f.; chan, s. k. s.; tam, c. c. t.; ho, p. l. title: border restriction as a public health measureto limit outbreak of coronavirus disease (covid- ) date: - - journal: nan doi: . / . . . sha: doc_id: cord_uid: qs w xh background: coronavirus disease (covid- ) led to pandemic that affected almost all countries in the world. many countries have implemented border restriction as a public health measure to limit local outbreak. however, there is inadequate scientific data to support such a practice, especially in the presence of an established local transmission of the disease. method: a novel metapopulation susceptible-exposed-infectious-recovered (seir) model with inspected migration was applied to investigate the effect of border restriction between hong kong and mainland china on the epidemiological characteristics of covid- in hong kong. isolation facilities occupancy was also studied. results: at r of . , the cumulative covid- cases in hong kong can be reduced by . % (from , to , ) with complete border closure. at an in-patient mortality of . %, the number of deaths can be reduced from to ( lives saved). however, border closure alone was insufficient to prevent full occupancy of isolation facilities in hong kong; effective public health measures to reduce local r to below . was necessary. conclusion: as a public health measure to tackle covid- , border restriction is effective in reducing cumulative cases and mortality. conclusion: as a public health measure to tackle covid- , border restriction is effective in reducing cumulative cases and mortality. all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted november , . ; https://doi.org/ . / . . . doi: medrxiv preprint article summary a novel metapopulation seir model with inspected migration was developed to investigate the epidemiological characteristics of covid- in hong kong, guangdong and the rest of china (excluding hubei) in the presence or absence of border restriction. the presented model is also suitable for further analysis of other emerging infectious diseases. border restriction is an effective public health measure in reducing cumulative cases and mortality for covid- . interaction was assumed to be well-mixed within patch. the spatial effect in disease transmission within each patch is ignored, which can have a non-trivial effect on the dynamic of infectious disease. the proposed model is deterministic in nature which ignores the randomness in migration and in the interactions among people; a stochastic model would be more realistic especially early in the disease. all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. whereas later cases were predominantly mediated by human-to-human transmission ( ) . transmission through asymptomatic contact also seemed highly probable ( ), a feature that was not previously seen with sars-cov or mers-cov. clinical spectrum of sars-cov- infection ranges from flu-like illness to pneumonia with rapid progression to acute respiratory distress syndrome (ards) and death ( , ( ) ( ) ( ) . among hospitalized patients, % to % had underlying disease and % to % of them required intensive care unit admission. the fatality rates for hospitalized covid- patients varies between · % to % ( , , ) but the true disease-specific mortality rate is unclear because the proportion of asymptomatic and mild infections remains uncertain. all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted november , . ; https://doi.org/ . / . . . doi: medrxiv preprint covid- rapidly evolved and became a pandemic. as of th july , there were more than million covid- over the world ( ) . to limit the scale of local disease outbreak, many countries implemented travel restriction towards travellers from regions with severe covid- outbreak and even all other countries, despite the world health organization (who) advising against implementing travel restriction as a public health measure to tackle covid- . hong kong is a special administrative region of the people's republic of china and border control exists between the two regions. owing to the tight geographical and socio-economic ties, more than forty-million individuals travelled from mainland china to hong kong in a year ( ) . china was the earliest country with covid- outbreak. on rd january , hong kong confirmed its first imported case of covid- from hubei ( ). in the subsequent weeks, the number of imported cases rapidly rose despite initiation of various public health measures. medical professionals and the general public repeatedly urged the hong kong government to close the hong kong-chinese border to stop further influx. however, some questioned the effectiveness of such measure as there was already sign of local transmission in hong kong. some believed that border restriction is not useful in the presence of established local transmissions as the final disease burden might be primarily driven by local transmission instead of importing of foreign cases. all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted november , . ; https://doi.org/ . / . . . doi: medrxiv preprint to date, there is inadequate scientific data to support border restriction as a public health measure to limit local outbreak of an emerging infectious disease in the presence of an established local transmission. the objective of this study is to assess the impact of border restriction on cumulative caseload and hospital occupancy with a novel metapopulation susceptible-exposed-infectious-recovered (seir) model with inspected migration. projection of covid- epidemiology in hong kong and mainland china will be performed as an illustration. all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted november , . ; https://doi.org/ . / . . . doi: medrxiv preprint in this study, a novel metapopulation seir model with inspected migration was applied to investigate the epidemiological characteristics of covid- in hong kong, guangdong and the rest of china (excluding hubei) in the presence or absence of border restriction. guangdong was separately analyzed from the rest of china because guangdong province had significantly higher confirmed cases per population ( · per million) than the rest of china (excluding hubei) ( · per million) as of th february . hubei province, with the highest case density in china ( · per million), was excluded from analysis as all hubei-hong kong travel was banned after the wuhan lockdown on rd january . real world data up to th february was used. seir type models are commonly adopted to simulate epidemiology of infectious disease of a single region over time. it is based on a system of ordinary differential equations (ode) that governs the number of types of individuals: susceptible (s), exposed but latent (e), infectious (i), and recovered (or death) (r). conventional single-patch seir models are not suitable for studying the impact of border restriction of an emerging infectious disease. a novel modified metapopulation seir model with inspected migration was used in this study. in addition to simulating population migration, parameters such as efficiency of custom inspection in blocking infected travellers were also being incorporated. details of the model were described in appendix . assumption all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted november , . ; https://doi.org/ . / . . . doi: medrxiv preprint it was assumed that there were no vital dynamics and well-mixed within patch for simplicity. disease transmission between patches was assumed to be contributed by migra- the mean incubation and infectious period was taken as · and · days respectively ( ) . coronavirus transmissibility has been hypothesized to reduce as temperature rises ( ), hence ܴ is set to be inversely correlated with temperature. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the hong kong public health system had a maximum of isolation beds in isolation single rooms according to the data from hospital authority press conference on st march . it was assumed that all isolation facilities were used exclusively for covid- purposes. all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted november , . of · - · , complete border closure was projected to cause a · - · % reduction in cumulative cases and mortality ( figure and table ). the results suggested that even in the presence of established local transmission, travel restriction remains an effective measure to reduce the cumulative cases in the recipient region. covid- associated mortality can also be decreased with this measure. maintaining complete border closure and having effective public health measures to keep ܴ below . is required to allow hong kong to meet its isolation room require-all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted november , . ; https://doi.org/ . / . . . doi: medrxiv preprint ment. other permutations are shown in table , and graphically represented in figure . countries or cities with a high population density and aged population including hong kong is at risk of severe outbreak of emerging infectious diseases such as covid- . as the disease is spreading rapidly in multiple continents, many countries implemented border restrictions towards regions with severe outbreak in order to reduce local case number and mortality. this is particularly important for developing countries with inadequate medical resources to tackle massive local outbreak. however, the who advised against utilizing travel restriction as an infection control measure. furthermore, it is particularly challenging to implement border restriction in certain regions due to political, social and economical reasons. to date there is inadequate scientific data to support border restriction as a public health measure to limit the scale of local outbreak in the presence of an established local transmission. using hong kong and mainland china as an example, we quantitatively illustrated border restriction is effective in reducing cumulative caseload, mortality and healthcare facility occupancy with a novel metapopulation seir model with inspected migration. it was projected that complete border closure will result in meaningful reduction of cumulative cases ( cases at ܴ of · ), mortality ( deaths at · % in-patient mortality) and a delay in isolation facility overload in hong kong. it is important to emphasize that in our projection, border closure alone is insufficient to prevent healthcare overload, as measured by isolation facilities occupancy. effective all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted november , . in the past few months, multiple regions had exponential rise in covid- cases which caused extreme stress to their local health care system. in wuhan, which was the epicenter of the covid- outbreak in china, severe shortage in isolation facilities urged urgent construction of multiple temporary hospitals. covid- related mortality in regions with severe outbreak tend to be higher due to relative shortage of medical resources outweigh demand. advanced life support facilities such as intensive care unit, ventilators, extracorporeal membrane oxygenation (ecmo) machines and anti-viral all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted november , . ; https://doi.org/ . / . . . doi: medrxiv preprint medications were essential in severe covid- cases but their availability is limited. in addition, covid- also severely hinder other non-covid- related medical services. in hong kong, although the total confirmed covid- cases is less than the available isolation facilities at the moment, a significant proportion of other less urgent medical services include elective investigations and surgeries have been suspended to reserve resources for covid- . in less resourceful regions, the effect may even be more pro- the spread of infectious disease is closely related to the migration of population between regions ( , ) . conventional single-patch seir models are not suitable for such analysis. a novel metapopulation seir model with inspected migration was specifically developed for this purpose. in addition to covid- , the developed model can be used to perform projection for other emerging infectious diseases in the future. furthermore, parameters such as effectiveness of custom inspection were included to improve all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted november , . ; https://doi.org/ . / . . . doi: medrxiv preprint accuracy of projection. the presented model is also suitable for further analysis of other emerging infectious diseases. firstly, interaction was assumed to be well-mixed within patch. the spatial effect in disease transmission within each patch is not directly addressed in the model, which can have a non-trivial effect on the dynamic of infectious disease ( ) . secondly, the proposed model is deterministic in nature which ignores the randomness in migration and in the interactions among people; a stochastic model would be more realistic especially early in the disease. thirdly, key parameters such as rate of spread is still unclear so we assumed a parametric form of the rate of spread with reference to -sars. in general, parameter calibration can be performed by some criteria, for example, minimizing residuals sum of square between the historical and fitted infected cases. meanwhile, missing information, such as travel history across regions, leads to crucial statistical uncertainty. a stochastic metapopulation migration model to explore the corresponding statistical properties with data would be a fruitful direction in the future. while the above shortcomings may be the expected tradeoff between computation time and model simplicity, it will not negate the signal that core message that border restriction reduces cumulative case, mortality and delay healthcare system exhaustion. lastly, economic impact is beyond the scope of this study. while full border closure can have a negative impact on the economy, one cannot ignore the negative economic impact from an otherwise preventable major outbreak. at time of writing, covid- was perceived to have developed into a pandemic situation and global stock market plummeted with the dow jones index and hang seng index both fell more than % percent since / / . all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted november , . ; https://doi.org/ . / . . . doi: medrxiv preprint as a public health measure to tackle covid- , border restriction is effective in reducing cumulative cases and mortality. hospital occupancy can be reduced but effective public health measures to achieve significant reduction in ܴ would be necessary to prevent full occupancy of available isolation facilities. all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted november , . ; https://doi.org/ . / . . . doi: medrxiv preprint this research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. no potential conflict of interest was reported by the authors. the lead author (the manuscript's guarantor) affirms that the manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained. ethical approval is not required as this study does not involve patients. our study is reported according to the gather statement. · data sharing: no additional data available. all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted november , . ; (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted november , . ; clinical characteristics of hospitalized patients with novel coronavirus-infected pneumonia in wuhan a pneumonia outbreak associated with a new coronavirus of probable bat origin early transmission dynamics in wuhan, china, of novel coronavirus-infected pneumonia. the new england journal of medicine transmission of -ncov infection from an asymptomatic contact in germany. the new england journal of medicine a familial cluster of pneumonia associated with the novel coronavirus indicating person-to-person transmission: a study of a family cluster clinical features of patients infected with novel coronavirus in wuhan epidemiologic and clinical characteristics of novel coronavirus infections involving patients outside wuhan -novel coronavirus ( -ncov): estimating the case fatality rate -a word of caution centre for health protection of the department of health h. latest situation of cases of novel coronavirus infection centre for health protection of the department of health h. severe respiratory disease associated with a novel infectious agent epidemiology and clinical presentations of the four human coronaviruses e, hku , nl , and oc detected over years using a novel multiplex real-time pcr method clinical characteristics of coronavirus disease in china impact of public health interventions in controlling the spread of sars: modelling of intervention scenarios population biology of infectious diseases: part ii cities and villages: infection hierarchies in a measles metapopulation no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity understanding the spatial clustering of severe acute respiratory syndrome (sars) in hong kong no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity hospitalized patients with novel coronavirus-infected pneumonia in wuhan, china a pneumonia outbreak associated with a new coronavirus of probable bat origin early transmission dynamics in wuhan, china, of novel coronavirus-infected pneumonia. the new england journal of medicine transmission of -ncov infection from an asymptomatic contact in germany. the new england journal of medicine a familial cluster of pneumonia associated with the novel coronavirus indicating person-to-person transmission: a study of a family cluster clinical features of patients infected with novel coronavirus in wuhan epidemiologic and clinical characteristics of novel coronavirus infections involving patients outside wuhan -novel coronavirus ( -ncov): estimating the case fatality rate -a word of caution centre for health protection of the department of health h. latest situation of cases of novel coronavirus infection epidemiology and clinical presentations of the four human coronaviruses e, hku , nl , and oc detected over years using a novel multiplex real-time pcr method clinical characteristics of coronavirus disease in china key: cord- -l r f sr authors: lee, chi-wei; tsai, yen-shuo; wong, tai-wai; lau, chor-chiu title: a loophole in international quarantine procedures disclosed during the sars crisis date: - - journal: travel med infect dis doi: . /j.tmaid. . . sha: doc_id: cord_uid: l r f sr this study describes a loophole in the international quarantine system during the recent asian severe acute respiratory syndrome (sars) outbreak. specifically, that of travelers disguising symptoms of respiratory tract infection at international airports, in order to board aircraft to return to their home countries—notwithstanding the infection risks this involves to others. high medical fees for treatment to non-residents in epidemic areas were found to be the main cause for this behaviour. this phenomenon revealed a loophole in the control mechanisms of international quarantine procedures, letting travelers carrying a highly contagious virus slip by undetected and causing possible multi-country outbreaks of communicable diseases. clinical evidence collected from medical records at medical centers can highlight this oversight. from november onwards, the severe acute respiratory syndrome (sars) had spread rapidly via international air travel to at least countries. as of december , , reported cases had numbered with deaths. reasons for its rapid global spread were the highly contagious nature of the virus with its air-borne route of infection, the busy links between affected countries, and probably inadequacies in international quarantine procedures. the increasing volume of international tourism and trade has raised the risks for translocation of exotic diseases. in other words, the increased mobility, mixing and congregation of civilian populations from different nations increase the rate of transmissible diseases. , countries need to cooperate more closely in the future, not only on finding the causes and the management of epidemic outbreaks, but also on preventing the further spread of them. for example, sars had affected people in many areas: in canada (toronto); in china (guangdong, hong kong, shanxi, beijing); in taiwan; in singapore; and in vietnam (hanoi). on march , , the world health organization (who) issued a global alert, . recommending that national authorities implement heightened surveillance for cases of sars. recommendations were aimed at limiting the spread of sars and protecting international air passengers. the screening measures for potential sars symptoms instituted by national health officials and port authorities, included interviews with passengers, as well as the taking of tympanic core body temperatures from boarding and disembarking passengers by way of electronic thermometers and infra-red cameras. national authorities also advised travelers with fever to postpone international travel from sars documented areas. international travelers were educated through the public media on the symptoms of sars and were advised to seek immediate medical attention should such symptoms occur. according to the who report, evidence had indicated that since the start of sars global surveillance at the end of february , a number of suspected and probable cases of sars had departed from affected countries on flights to other countries (http://www.who.int/csr/sars/ archive/ _ _ /en/). local transmission could conceivably have occurred inside the cabin of an aircraft to persons seated close to a sars infected person, by way of droplets discharged through coughs or sneezes. in total, nations ( administrative independent regions, including hong kong) were reported up to april , to be infected by the sars epidemic, in part a consequence of international travel. in fact, the international traveler is an efficient vector for sars as well as new respiratory pathogens yet to emerge. the aim of this study is to describe reasons for a loophole in international quarantine procedures. this study was divided into two parts: information was collected at the international airport of kaohsiung (taiwan), on the physical conditions of passengers who flew from hong kong and landed at kaohsiung from april to , . this information was compiled from questionnaires and brief interviews of arriving passengers. in addition, information was gathered from body temperature measurements performed on each arriving passenger who entered taiwan. records from at the emergency department of e-da hospital, in southern taiwan, of patients suffering from symptoms of respiratory tract infection who had departed recently from sars areas from march , onwards were analyzed. the investigation revealed that during this period a total of passengers were symptomatic during transit on board aircraft, meaning that at least and at most passengers per day were found to be symptomatic during their flight. since the flying time from hong kong to kaohsiung is only to minutes, it is reasonable to suspect that symptomatic passengers were actually aware of their symptoms before boarding the aircraft. thus they fully understood that they were possibly infected with the sars virus when departing from an endemic area and before heading for taiwan, despite the aggressive screening procedures put in place by the hong kong customs and department of health at hong kong's international airport. in order to explain the circumstances for this observed phenomenon and the underlying reasons for such behavior, we proceeded to the second part of our study. here, six patients visiting the emergency department of e-da hospital, from march to , , were found to show symptoms from respiratory tract infections, after they had departed from a sars endemic area and had entered the territory of taiwan by air. as shown in tables and , although none of the six patients were eventually diagnosed wild sars, this observed phenomenon disclosed a very important loophole in the control aspect of international quarantine procedures: the inability to prevent persons with a highly contagious virus from slipping past undetected and thus preventing the further spread of epidemics like sars on international travel routes. all of these patients admitted that extraordinarily high medical fees for non-residents in hong kong, was the major reason for them to hurry back to taiwan, where the cost medical care is significantly lower. in this study, we identified that there were loopholes in the international quarantine system for controlling the international spread of contagious disease like sars, especially when travelers lack a strong motivation to cooperate with national health authorities. this arises particularly when the high medical fees are imposed on non-local residents in endemic areas, were a significant financial burden. furthermore, the emergency room's medical records showed that patients were already aware of their symptoms such as cough or indications of high fever (though not necessarily sars) before they boarded their respective fights. nevertheless, they denied being sick before departure when questioned by health authorities, in full awareness of the infection risks, in order to reach taiwan. since taiwanese residents benefit from very low medical fees in their health care system, in contrast to hong kong's high hospital fees for non-residents. taiwan's medical fees are only v . (nt$ ) per attendance in the emergency room and just % of the total medical expense during the course of admission for in-patient care at a district hospital, with the remaining cost being subsidized by the national health care plan (see table ). tables and show a strong correlation in different medical fees for residents and non-residents both in hong kong and singapore. for example, the admission fee for in-patient care (general acute beds) is v . (hk$ ) per day in hong kong for residents or hong kong identity card holders, while a non-hong kong resident has to pay v . (hk$ , ) per day for the same treatment- times higher. in comparison, all taiwan nationals and residents are covered under the policy of the national health care insurance plan, and thus pay less than v . (nt$ ) per day for in-patient care. this cost differentiation for residents and non-residents in hong kong, is a phenomenon observed almost in every country in the world, with similar examples existing among different member countries in the patients admitted that they were symptomatic before their departure from epidemic areas of sars. european union. this is only a natural human response for a symptomatic traveler to disguise his/ her illness at their point of departure, to flee back to his/her home country for medical care at a significantly lower cost. however, this apparent trivial aspect of human behavior turns out to be a very serious problem in terms of epidemics and quarantine control measurements, where communicable diseases could be introduced into a population by the arrival of outside foreign infectives. citing the example discussed here, the possibility exists that travelers may return home from a foreign trip with an infection acquired abroad. while an experimental model indicates that screening and quarantining of infectives can considerably reduce the infective equilibrium. the egocentric human behavior of certain travelers who break quarantine rules, could be modified by better cooperation between governments. in today's highly mobile society, it is crucial to deter international travelers from spreading contagious diseases during an epidemic and lessons may be learned from the worldwide spread of sars so that precautions can be taken in the policy-making process for the future since a similar tragedy may repeat itself anytime, anywhere in the world. in response to the main issue identified in this report, governments need to set sensible medical fees for the temporary hospitalization of 'aliens' staying in their territories during periods of epidemic outbreaks. this cost could be shared by governments across the globe, with coordination by the who, so as to enforce quarantine measurements more efficiently. the existing cross-border care and international payment coverage policy within the european union can be seen as a good reference base for constructing such a cross-linking system to tackle this emergent problem of international quarantine. this measure may stop people from becoming disease-vectors within their home countries and also to other passengers on the same plane who may carry infection to many different destinations all over the world. thus, it is of importance, that governments in endemic areas publicize such policies, targeting foreigners staying within their boundaries during an outbreak. it is estimated that the sum of inter-governmental medical expenses incurred by infective or potential infective patients hospitalized at sensible cost in the 'host countries', would be substantially lower than the total social costs caused by the spread of communicable diseases, if these infectives were allowed to return to their mother countries. thus, the aim of future research should be focused on the health and safety investment as well as risk control methods. since global surveillance of sars began at the end of february , some evidence has suggested that a number of suspect and probable cases of sars were caused by persons being infected during travel on board aircraft (http://www.wpro.who. int/sars/docs/interimguidelines/part .asp). they were probably seated in close proximity to persons releasing droplets in the air on coughing or sneezing. such cases, gives impetus to more rigorous measures to prevent travel-related spread of sars or other communicable diseases. thus stricter travel enforcement must also be evaluated and added to existing quarantine measurements. this is in addition to the main focus of cross-border care and international payment coverage policies for aliens or temporary 'visitors' in afflicted areas. this sars outbreak may be regarded as a test of whether rigorous contact tracing and other stringent public health measures contained further spread, even though a large numbers of persons may have inadvertently been exposed to the virus. one intervention procedure to control the spread of infectious diseases is to isolate some infectives in order to reduce possible transmissions of the infection to susceptibles. total isolation may have been the first historical known infection control method, since biblical passages refer to the ostracism of lepers, then later in time plague victims were often isolated. the word 'quarantine' meant historically a period of days, the length of time that arriving ships suspected of plague were required to lay in anchor off the harbour before being allowed to dock. this practice started in the th century at mediterranean ports during the outbreak of the bubonic plague. the word quarantine has evolved to signify a forced isolation or a stoppage of interactions with others. over the centuries, quarantine has been used to reduce the transmission of human communicable diseases such as leprosy, plague, cholera, typhus, yellow fever, smallpox, diphtheria, tuberculosis, measles, mumps, ebola and lassa fever. the 'influenza pandemic preparedness plan' developed in the united states of america is an excellent model from which every other country in the world should learn and extrapolate its underlying spirit. this plan has as objectives: to limit the burden of communicable diseases, to minimize social disruption and to reduce economic loss in the future when similar outbreaks of pandemic does occur. early in , epidemiologists had warned the world that should the next pandemic be caused by a virus as deadly as that of influenza pandemic, the potential for disaster would be greater than ever. as the world's population is now more than three times greater than it was in , with nearly half that population residing in urban areas, including hundreds of millions crowded into slums and shanty towns in the developing world. faced with today's highly mobile transportation links, a virulent virus could easily spread around the world in a matter of days. another pandemic would challenge the world's public-health resources as never before. therefore, an effective response to future pandemics of viral infection proportions, such as the influenza pandemic, will demand the full support and complete cooperation of the public. yet the global health community is not prepared for the next viral pandemic, according to klaus stöhr (who, geneva, switzerland), speaking at the international congress on infectious diseases (singapore, march - , ) . furthermore, mankind's history and this case study provides evidence that travelers have contributed significantly to the rapid spread of aids , , influenza , and sars, therefore strict international quarantine enforcement, must be considered for future epidemics. only then, would we be ready to confront similar or even tougher challenges of pandemic outbreaks. in fact, bilateral, as well as regional agreements among different governments on visitors' health care are becoming more common. for example, an extensive list of countries has reciprocal health care agreements with the united kingdom. other non-economic reasons for return home of febrile passengers during the sars epidemic include fear for being infected in the epidemic region, reluctance to be isolated in a foreign country, unfamiliarity with foreign culture, planned travel schedule, etcetera. nevertheless, according to the record of the medical history taken in our emergency department, all six patients admitted that the big gap between medical costs in a foreign country and their mother country was the main reason for disguising their fever on departure. in contrast to sea-voyage, air travel journey is relatively short in duration. infected crew or passengers who travel on board ships would have their diseased status shown clearly during the long sea-voyage, and would have died or being quarantined when they arrived at their destined port. however, due to the relatively short duration of air-travel, the clinical condition of infected passengers on board airplane would not have sufficient time to progress to a serious stage which is obvious enough to detected by the custom at the destined airport. here lies the loophole of international quarantine which would be easily overlooked by airport custom, but not sea-port custom. thus, emergency departments or walk-inclinics are playing the important role in safeguarding the community from imported infectious diseases. emergency physicians should maintain a high level of awareness regarding potential outbreaks of infectious diseases of any kind and play a role in alerting public health authorities to any loopholes in quarantine procedures. the vulnerability of animal and human health to parasites under global change the philippines insurrection and the - cholera epidemic: part i-epidemiological diffusion processes in war the philippines insurrection and the - cholera epidemic: part ii-diffusion patterns in war and peace sars-lessons learned so far healthcare access and mobility between the uk and other european union states: an 'implementation surplus models for transmission of disease with immigration of infectives should i stay or should i go? waiting lists and cross-border care in the netherlands health a review of the application of health economics to health and safety in healthcare effects of quarantine in six endemic models for infectious diseases influenza pandemic planning: review of a collaborative state and national process epidemic and pandemic 'flu ready for the next influenza pandemic? hiv and pandemic influenza virus: two great infectious disease challenges travel and the spread of hiv- genetic variants further development of influenza surveillance in china and global impact on influenza control key: cord- - pc eji authors: de jong, menno d.; hien, tran tinh title: avian influenza a (h n ) date: - - journal: j clin virol doi: . /j.jcv. . . sha: doc_id: cord_uid: pc eji since their reemergence in , highly pathogenic avian influenza a (h n ) viruses have reached endemic levels among poultry in several southeast asian countries and have caused a still increasing number of more than reported human infections with high mortality. these developments have ignited global fears of an imminent influenza pandemic. the current knowledge of the virology, clinical spectrum, diagnosis and treatment of human influenza h n virus infections is reviewed herein. periodically, completely novel antigenic subtypes of influenza viruses have been introduced in the human pop- * corresponding author. tel.: + ; fax: + . ulation, causing large-scale global outbreaks with high death tolls. the most devastating influenza pandemic in modern recorded history, known as the "spanish flu", occurred in - , killing up to million people worldwide. other less destructive pandemics during the previous century occurred in and . avian influenza a viruses are key to the emergence of human influenza pandemics. the virus strains implicated in the th century's influenza pandemics originated directly from avian influenza viruses, either through genetic reassortment between human and avian influenza strains ( and ) or possibly through adaptation of purely avian strains to humans ( ) . it was long thought that the restricted host range of avian influenza viruses precluded direct transmission to humans, and that the emergence of pandemic strains required genetic reassortment between avian and human strains. however, occurrences of direct bird-to-human transmission of avian influenza viruses have increasingly been reported in recent years, culminating in the ongoing outbreak of influenza a (h n ) among poultry in several asian countries with associated human infections. these unprecedented developments have resulted in increasing global concerns about the pandemic potential of these viruses. influenza viruses are pleomorphic, enveloped rna viruses belonging to the family of orthomyxoviridae. protruding from the lipid envelope are two distinct glycoproteins, the hemagglutinin (ha) and neuraminidase (na) . ha attaches to cell surface sialic acid receptors, thereby facilitating entry of the virus into host cells. since it is the most important antigenic determinant to which neutralizing antibodies are directed, ha represents a crucial component of current vaccines. na is the second major antigenic determinant for neutralizing antibodies. by catalyzing the cleavage of glycosidic linkages to sialic acid on host cell and virion surfaces, this glycoprotein prevents aggregation of virions thus facilitating the release of progeny virus from infected cells. inhibition of this important function represents the most effective antiviral treatment strategy to date. a third membrane protein, the m protein, is present in small quantities in influenza a viruses. by functioning as an ion channel, this protein regulates the internal ph of the virus, which is essential for uncoating of the virus during the early stages of viral replication. this function is blocked by the antiviral drugs amantadine and rimantadine. the genome of influenza viruses is segmented, consisting of single-stranded, negative sense rna molecules, which encode proteins. the rna segments are contained within the viral envelope in association with the nucleoprotein (np) and three subunits of viral polymerase (pa, pb , and pb ), which together form the ribonucleoprotein (rnp) complex responsible for rna replication and transcription. additional proteins contained within the virion include m and the viral nuclear export protein (nep), which function in assembly and budding, and export of rnp from the nucleus, respectively. based on antigenic differences in np and m proteins, influenza viruses are classified as types a, b, and c. influenza b and c viruses are not divided into subtypes. all avian influenza viruses are classified as type a. further subtyping of influenza a viruses is based on antigenic differences between the two surface glycoproteins ha and na. to date, ha subtypes (h -h ) and na subtypes (n -n ) of influenza a viruses have been identified (fouchier et al., ) . the standard nomenclature for influenza viruses includes the influenza type, the host of origin (excluding humans), the place of isolation, the strain number, the year of isolation, and finally the influenza a subtype in parentheses (e.g. a/duck/vietnam/ / (h n )). the natural reservoir of influenza a viruses are aquatic birds, in which the viruses appear to have achieved an optimal level of host adaptation (webster et al., ) . transmission between birds occurs directly or indirectly through fecally contaminated aerosols, water, feed, and other materials. the spectrum of disease in birds ranges from asymptomatic infection, to mild respiratory illness, to severe and rapidly fatal systemic disease. most avian influenza viruses isolated from birds are avirulent, i.e. result in asymptomatic infection or only mild disease. avian influenza viruses capable of causing outbreaks of severe disease (fowl plague) in chickens or turkeys are classified as highly pathogenic, and are currently restricted to h and h subtypes. infection of poultry by highly pathogenic avian influenza viruses is characterized by disseminated infection, and clinically manifested by decreased egg production, respiratory signs, excessive lacrimation, edema of the head, diarrhea, neurological symptoms, and death. from the principal reservoir of aquatic birds, viruses are occasionally transmitted to other animals, including mammals and domestic poultry, causing transitory infections and outbreaks. through adaptation by mutation or genetic reassortment, some of these viruses may establish speciesspecific permanent lineages of influenza a viruses, and cause epidemics or epizootics in the new host. in the human population, the establishment of these lineages in the th century was preceded by influenza pandemics. transmission of viruses and transitory infections may also occur among the new hosts, e.g. between humans and pigs or chickens and humans. although all ha and na subtypes are found in aquatic birds, the number of subtypes that have crossed the species barrier and established stable lineages in mammals is limited. only three ha and two na subtypes (i.e. h - and n - )) have circulated in humans since . in horses, only two influenza a subtypes (h n and h n ) are found, while, despite susceptibility to all avian subtypes in experimental settings, the only subtypes recovered from pigs in nature are h , h , n , and n . the molecular, biological or ecological factors determining the apparent subtype-specific ability of viruses to cross species barriers and spread among a range of hosts remain largely unresolved. while interspecies transmission does occur at times, there certainly are host range restrictions. human influenza strains preferentially bind to sialic acid residues linked to galactose by the ␣ , linkage, while avian and equine influenza strains recognize sialic acid linked to galactose by ␣ , linkage (connor et al., ; gambaryan et al., ; matrosovich et al., matrosovich et al., , rogers and d'souza, ; . correspondingly, human respiratory epithelial cells predominantly contain ␣ , sialic acid-galactose linkages, while the host cells in birds and horses mainly contain ␣ , linkages (couceiro et al., ; ito et al., ; matrosovich et al., ) . respiratory epithelial cells in the pig contain both ␣ , and ␣ , linkages, which explains why this animal is susceptible to both human and avian influenza viruses (ito et al., ) . because of this trait, the pig is widely regarded as a potential source of new pandemic strains, since it could serve as a non-selective host in which mixed infection of avian and human strains efficiently occurs, potentially resulting in new reassortant viruses, or in which purely avian strains can adapt to human receptor recognition. introduction of an influenza a virus with a novel ha gene in a population which lacks immunity to this ha has the potential to cause a pandemic when the virus posesses the ability to spread efficiently among humans. during the th century, this has happened three times, in , , and , killing millions of people worldwide. in all three pandemics, the viruses originated from avian influenza viruses. the virus strains responsible for the influenza pandemics of and both first emerged in southeastern asia, and both arose through reassortment of genes between avian viruses and the prevailing human influenza strain (scholtissek et al., ) . the "asian influenza" pandemic of was caused by an h n virus that had acquired three genes (h , n , and pb ) from avian viruses infecting wild ducks, in a backbone of the circulating h n human influenza strain. as the asian flu strain emerged and established a permanent lineage, the h n strains soon disappeared from the human population for unclear reasons. similarly, the h n virus causing the "hong kong influenza" pandemic of consisted of two genes from a duck virus (h and pb ) in a background of the human h n strain circulating at that time. the latter virus disappeared with the emergence of the h n virus and since then has not been detected in humans. sequence analysis of the hypothetical precursor strain, which immediately preceded the pandemic h n virus suggested that fewer than six amino acids in ha had changed during the avian-to-human transition . interestingly, a number of these changes may reflect adaptation to the new host since they modified the area surrounding the receptor-binding pocket of ha, including a glu to leu change at position which is particluarly implicated in determining specificity for human receptors. the fact that, beside one or two novel surface glycoproteins, both pandemic strains also posessed a pb gene of avian origin is intriguing and may suggest a role of this gene in interspecies transmission (kawaoka et al., ) . although millions of people died during the and pandemics, the viruses involved did not appear particularly virulent, suggesting that lack of immunity was the main reason for the excess mortality. this was different during the "spanish flu" pandemic of , in which lack of immunity in the human population was combined with an apparent extremely high virulence of the virus, resulting in the demise of up to million people worldwide. because the pandemic occurred before viruses were identified as the causative agents, no intact virus has been available for analysis. this and the similar lack of available human and animal influenza strains circulating before has made it difficult to determine the exact origin of the pandemic h n virus and the reason for its extreme virulence. however, valuable insight has been provided by the recovery of fragments of viral rna isolated from archived autopsy specimens and tissue from alaskan flu victims buried in the permafrost (taubenberger et al., ) . this enabled sequence analysis of five of the eight genes (ha, na, np, m, and ns) (reid et al., ) . phylogenetic analyses of these genes suggest that the h n virus may not have arisen by the same mechanism as the and pandemic viruses, i.e. by reassortment of avian and human influenza viruses, but perhaps by direct transmission from an avian source after adaptation in humans or another permissive mammalian host, such as the pig (reid et al., ) . this is supported by the observation that the pandemic strain retained the amino acid residues at positions and of ha predictive for binding to avian receptors (taubenberger et al., ) . recent chrystallographic studies showed that structural changes in the h ha allowed the virus to recognize human receptors despite the presence of these avian-like residues, which may explain why the virus could nevertheless efficiently infect and spread among humans (gamblin et al., ; stevens et al., ) . the possibility that the strain had retained the structure and biological properties of its avian ancestors while acquiring the ability to recognize and efficiently infect human cells may explain the high virulence of this virus. mathematical modelling studies have suggested that the transmissability of the virus was not remarkably different than regular human influenza strains, suggesting that extremely efficient spread did not account for the high morbidity and mortality (mills et al., ) . while part of the high mortality of the pandemic could be explained by the lack of antibiotics to treat secondary bacterial pneumonia and poor living conditions, the extremely rapid and severe clinical course implies high pathogenicity of the virus as the major cause. the molecular basis for this high virulence remains unclear. the h ha lacks the multibasic cleavage site characteristic of highly pathogenic avian influenza viruses (reid et al., ; taubenberger et al., ) . there are conflicting observations concerning the role of the ns gene in the pandemic strain. in mice, the presence of the complete ns or only the ns segment seemed to confer decreased, rather than enhanced pathogenicity of reassortant h n viruses (basler et al., ) . in contrast, in vitro experiments in human lung cells suggested more efficient inhibition of interferon-regulated genes by h n virus in the presence of the ns gene (geiss et al., ) . the most convincing evidence implicates ha as an important determinant of the high virulence. the presence of ha of the virus conferred high pathogenicity in mice to human strains that were otherwise non-pathogenic in this host (kobasa et al., ) . furthermore, these infections were associated with severe hemorrhagic pneumonia and the induction of high levels of macrophage-derived cytokines and chemokines, strikingly reminiscent of clinical observations in humans during the spanish flu pandemic, as well as of recent in vitro and in vivo observations of infections with highly pathogenic avian influenza h n viruses (cheung et al., ; oxford, ; peiris et al., ; to et al., ) . in recent years, it has become clear that human infections with highly pathogenic influenza h n viruses are associated with severe, often fatal disease. in may , following outbreaks of influenza h n among poultry on three farms in the new territories of hong kong, an influenza h n virus was isolated from a -year-old boy in hong kong, who died of severe pneumonia complicated by acute respiratory distress syndrome and reye's syndrome (subbarao et al., ) . in november and december of the same year, concomittant with outbreaks of influenza h n among chickens in poultry markets and on farms in hong kong, additional cases of human h n infections were identified, of which were fatal (chan, ; yuen et al., ) . the outbreak was contained after the slaughtering of all . million chickens in hong kong. in response to the outbreak, influenza surveillance in poultry was intensified permitting early recognition of other outbreaks of avian influenza in and . no further human h n infections were reported until february , when two laboratory-confirmed cases and one probable case were identified in one family from hong kong (peiris et al., ) . the daughter died of an undiagnosed respiratory infection while visiting fujian province in mainland china. upon their return to hong kong, the father and son developed severe respiratory illnesses of which the father died. h n virus was isolated from both patients. in december , an outbreak of highly pathogenic h n virus was identified among poultry in the republic of korea (lee et al., ) . subsequently, outbreaks by antigenically related viruses were reported among poultry in thailand, viet nam, japan, china, cambodia, laos, malaysia, and indonesia. the reason for this apparent simultaneous occurrence of h n outbreaks in many asian countries remains unclear. however, h n viruses have also been found in dead migratory birds, which may suggest a role of wild birds in the maintenance and spread of h n viruses in the region (chen et al., ; li et al., ) . human infections during the southeast asian outbreaks were first reported in early from viet nam and thailand, followed by still ongoing resurgences of human cases in viet nam, cambodia, and indonesia from then onwards (chotpitayasunondh et al., ; tran et al., ) . at the time of this writing (august ), the total number of confirmed human cases of influenza h n in the countries amounts to (thailand: ; cambodia: ; indonesia: ; viet nam: ), of which were fatal (who, ) . it cannot be excluded and may even be likely that additional cases have gone unnoticed in these and other affected countries due to a lack of clinical awareness, active surveillance, or diagnostic facilities (hien et al., ) . while many countries initially affected by poultry outbreaks in have been declared free of the virus, h n virus seems to have reached endemic levels in poultry and aquatic birds in several asian countries, despite attempts to contain the outbreak by extensive culling of poultry. in these countries, continuing occurrences of bird-to-human transmissions increase the opportunity of the virus to adapt to humans and acquire the ability to spread between humans. in addition, continuing cocirculation of avian and human viruses in these countries, where humans live in close proximity with poultry and pigs, increases the risk of reassortment between both in co-infected humans or other mammalian hosts, such as the pig. the recent isolation of h n viruses from pigs in china (chen et al., ) , and, albeit at low prevelance, the detection of h n antibodies in vietnamese pigs (choi et al., ) , are concerning in this respect. for all these reasons, the current developments in southeast asia seem to justify the global concern that, similar to and , a new pandemic influenza strain may emerge from this region in the near future. at presentation, most cases of human h n infections were characterized by a severe influenza syndrome, clinically indistinguishable from severe human influenza, with symptoms of fever, cough and shortness of breath, and radiological evidence of pneumonia (chotpitayasunondh et al., ; tran et al., ; yuen et al., ) . abnormalities on chest radiographs at presentation included extensive, usually bilateral infiltration, lobar collapse, focal consolidation, and air bronchograms. radiological evidence of pulmonary damage could still be observed in surviving patients several months after the illness. beside respiratory symptoms, a large proportion of patients also complained of gastrointestinal symptoms such as diarrhea, vomiting, and abdominal pain, which are common in children with human influenza, but not in adults. in some cases, diarrhea was the only presenting symptom, preceding other clinical manifestations (apisarnthanarak et al., ; de jong et al., ) . unlike human infections with h or h viruses, conjunctivitis was not prominent in h n -infected patients. the clinical course of the illness in severe cases was characterized by rapid development of severe bilateral pneumonia necessitating ventilatory support within days after onset. complications included acute respiratory distress syndrome, renal failure, and multi-organ failure. evidence that the clinical spectrum of human h n infections is not restricted to pulmonary symptoms was provided by a reported case of possible central nervous system involvement in a vietnamese boy who presented with diarrhea, followed by coma and death. influenza h n virus was isolated from throat, rectal, blood, and cerebrospinal fluid specimens, suggesting widely disseminated viral replication (de jong et al., ) . his sister had died of a similar illness weeks earlier, but no diagnostic specimens were obtained. although highly virulent h n viruses have shown neurotropism in mammals such as mice and cats (keawcharoen et al., ; lipatov et al., ; tanaka et al., ) , these cases may be similarly rare as central nervous system manifestations associated with human influenza (morishima et al., ; sugaya, ) . genetic predisposition of the host to such manifestations may play a role. striking routine laboratory results in h n -infected patients, especially in severe cases, were an early onset of lymphopenia, with a pronounced inversion of the cd +/cd + ratio, thrombocytopenia and increased levels of serum transaminases (chotpitayasunondh et al., ; tran et al., ; yuen et al., ) . high levels of cytokines and chemokines have been observed in several h n -infected patients, suggesting a role of immune-mediated pathology in the pathogenesis of h n infections (peiris et al., ; to et al., ) . this was supported by pathological examination in two patients who died during the outbreak in hong kong, which showed reactive hemophagocytosis as the most prominent feature . other findings included diffuse alveolar damage with interstitial fibrosis, hepatic central lobular necrosis, acute renal tubular necrosis, and lymphoid depletion. although the gastrointestinal, hepatic, renal, and hematologic manifestations could suggest wider tissue tropism, there was no evidence of viral replication in organs outside the respiratory tract . however, viral replication in the gastrointestinal is strongly suggested by reported virus isolation and detection of positive strand viral rna from fecal specimens (de jong et al., ; uiprasertkul et al., ) . while many laboratory-confirmed h n infections were associated with severe, often fatal disease, milder cases have also been reported, especially during the outbreak in hong kong (chan, ; yuen et al., ). an increasing number of milder cases also seemed to occur in viet nam, as the outbreak progressed in (who, ) . while increased clinical awareness and surveillance may account for such observations, progressive adaptation of the virus to humans is the dreaded alternative explanation. the occurrence of mildly symptomatic and asymptomatic infections have also been suggested during the outbreak in hong kong by seroepidemiological studies in household members of h n -infected patients and health care workers. in these studies, of exposed and of non-exposed healthcare workers were seropositive for h n -specific antibodies (bridges et al., ) . seroconversion was documented in two exposed nurses, one of whom reported a respiratory illness days after exposure to an h n -infected patient. more importantly than showing the occurrence of asymptomatic infections, these data indicated that nosocomial person-to-person transmission had occurred, albeit limited to a few cases. an additional case of possible human-to-human transmission during the hong kong outbreak was suggested by h n -seropositivity in a household contact of a patient, who had no history of poultry exposure (katz et al., ) . seroepidemiological studies in health care workers involved in the care of h n infected patients in thailand and viet nam in have not shown evidence of person-to-person transmission, despite the absence of adequate infection control measures in the vietnamese cohort at the time of study (apisarnthanarak et al., ; liem and lim, ; schultsz et al., ) . during the outbreak in thailand in , extensive epidemiological investigations have suggested person-to-person transmission from a child, who died of presumed h n infection, to her mother who had no history of exposure to poultry and had provided prolonged unprotected nursing care to her daughter . an aunt of the child may have been infected by the same route since her last exposure to poultry before infection had been days, considerably longer than the estimated incubation period of - days. there have been several similar family clusters of h n cases in viet nam, which have all ignited concerns about the possibility of human-to-human transmission, but most of which could be explained by common exposure to poultry. while there has been no evidence of efficient transmission of influenza h n virus between humans to date, caution and detailed investigations remain warranted in case of any cluster of infections, especially in view of the relatively rapid evolution h n viruses have exhibited in recent years. in , an h n virus was isolated from geese during an outbreak in guangdong province in china (influenza a/goose/guangdong/ / (a/g/gd/ )) (xu et al., ) . this virus proved to be the donor of the ha gene of the reassortant h n viruses causing the outbreak among poultry and humans in hong kong in . the internal genes of the hong kong h n viruses were closely related to those of an h n virus isolated from quail (guan et al., ) . the origin of the na gene remains unclear, but was notable for a -amino acid deletion in the stalk region (subbarao et al., ) . such deletions may be associated with adaptation of influenza viruses to land-based poultry (matrosovich et al., ) . the ha gene contained multibasic sequences at the cleavage site, in accordance with its classification as a highly pathogenic strain (claas et al., ; matrosovich et al., ) . after the eradication of the hong kong strain, the goose precursor viruses continued to circulate in geese in southeastern china (cauthen et al., ; webster et al., ) . through reassortment between this virus and other avian viruses, multiple antigenically similar genotypes, that were highly pathogenic in chickens but not in ducks, emerged and again were eradicated in hong kong in and . then, in late , h n strains isolated from wild migratory birds and resident waterfowl in two hong kong parks showed marked antigenic drift and exhibited high pathogenicity in ducks sturm-ramirez et al., ) . the latter property is rarely found in nature, and had not been observed in strains isolated during previous years. an antigenically and molecularly similar virus caused the two confirmed human infections in early in a family from hong kong peiris et al., ) . h n influenza viruses isolated from healthy ducks in southern china between and were all antigenically similar to the precursor influenza a/g/gd/ virus (chen et al., ) . it is thought that these ducks played a central role in the generation of the virus responsible for the outbreaks in southeast asia since . detailed genetic analyses of h n strains isolated during the period - from poultry and humans in china, hong kong, indonesia, thailand, and viet nam, demonstrated that a series of genetic reassortment events, all traceable to the a/g/gd/ -precursor virus, ultimately gave rise to a dominant h n genotype (genotype z) in chickens and ducks . this genotype is implicated in the human cases in hong kong in and the outbreaks among poultry and humans since . the evolution of h n viruses in recent years has been associated with increasing virulence and an expanding host range, which beside terrestrial poultry and wild birds, also includes mammals. while all h n viruses isolated from ducks in china between and were highly pathogenic in chickens, an increasing level of pathogenicity was observed in mice with the progression of time: virus isolated in and were less pathogenic than those isolated in and (chen et al., ) . it has been suggested that the increasing ability to replicate in mammals has resulted from transmission between ducks and pigs. the expanding host range is also illustrated by successful experimental infection of domestic cats, and natural infections of tigers and leopards with recent h n strains (keawcharoen et al., ; kuiken et al., ) . in summary, continued evolution of h n viruses since , involving multiple genetic reassortment events between a/g/gd/ -like viruses and other avian viruses and perhaps transmission between birds and pigs or other mammalian hosts, have resulted in a highly virulent genotype with an expanded host range which is now causing widespread outbreaks among poultry and humans in southeast asia. while transmission between birds and humans at present still seems inefficient, as does transmission between humans, this may change when the virus is allowed to continue its evolution through adaptation and reassortment. although virus isolation remains the gold standard of diagnosis and indispensable for virus characterization, rapid laboratory confirmation of suspected human influenza in routine diagnostic laboratories is usually performed by immunochromatographic or immunofluorescent detection of influenza virus antigens, or reverse transcriptase (rt) pcr detection of viral nucleic acids in respiratory specimens. in addition, serological evidence of human influenza a virus infection can be obtained by commercially available elisa kits which detect antibodies to conserved viral antigens, such as the nucleoprotein. in the absence of cocirculating avian influenza strains in the human population, further subtyping of influenza viruses or detection of subtype-specific antibodies are usually not done by routine diagnostic laboratories, but are restricted to reference laboratories involved in epidemiological analyses and planning of vaccine strains. however, in case of an outbreak of avian influenza, efforts to further subtype the virus, e.g. by subtype-specific rt pcr methods, should be made by routine laboratories since immediate knowledge about the infecting influenza subtype is essential for infection control and timely epidemiological investigations. dependence on reference laboratories, which in the case of many southeast asian countries affected by avian influenza outbreaks, are situated abroad, potentially results in unacceptable delays and hampers timely recognition of outbreaks and institution of adequate control measures (hien et al., ) . however, the reality is that diagnostic facilities in many affected countries are scarce and often not sufficiently equipped for virological diagnostics, let alone subtyping of influenza viruses. global efforts to improve diagnostic capacity in resource-poor countries may prove an important step towards the prevention and control of pandemic influenza (hien et al., ) . similar to human influenza viruses, avian viruses can be isolated in embryonated eggs or in cell culture, using permissive cells such as madin darby canine kidney (mdck) cells or rhesus monkey kidney (llc-mk ) cells. unlike human strains and avirulent avian strains and in accordance with their promiscuity for cellular proteases, highly pathogenic avian viruses do not require the addition of exogenous trypsine for efficient replication in cell culture. for safety purposes, the isolation of highly pathogenic avian influenza virus requires biosafety level laboratory facilities or higher. cytopathic effects in cell culture are non-specific. initial identification of influenza a virus can be performed by immunofluorescent staining with monoclonal antibodies against the nucleoprotein. further ha and na subtyping is performed by subtype-specific rt pcrs of culture supernatant or hemag-glutination inhibition and neuraminidase inhibition assays using a panel of reference antisera against various subtypes. in human infections, avian influenza viruses have mostly been isolated from conjunctival swabs and respiratory specimens such as throat or nasal secretions or washings tran et al., ; yuen et al., ) . in one reported case of h n infection, virus was also isolated from serum, cerebrospinal fluid, and a rectal swab (de jong et al., ) . detection of influenza a viral antigens in clinical specimens by direct immunofluorescence or by rapid immunochromatographic assays are widely used for diagnosis of human influenza because of their ability for rapid diagnosis. however, in patients with avian influenza, the usefulness of these assays seems limited due to low sensitivity (peiris et al., ; yuen et al., ) . in addition, some rapid antigen detection kits do not distinguish between influenza types a and b, and none of the currently available immunofluoresent and immunochromatographic assays distinguish between influenza a subtypes. however, developments of h n -specific rapid antigen detection tests are ongoing . rt pcr methods allow for sensitive and specific detection of viral nucleic acids and have shown to increase the diagnostic sensitivity for many viral pathogens when compared to culture or antigen detection methods. during the h n outbreaks in hong kong and southeast asia, rt pcr methods for specific detection of h n viral nucleic acids have proven valuable and seem the diagnostic methods of choice in case of an outbreak of avian influenza (chotpitayasunondh et al., ; tran et al., ; yuen et al., ) . especially when using real-time pcr technology, a reliable subtype-specific diagnostic result can be generated within a few hours after specimen collection. a disadvantage of rt pcr methods is its proneness for contamination and the consequent risk of false-positive results, which should be be minimized by proper precautions, including physical separation of laboratories for pcr preparation and amplification, and the use of the uracil-n-glycosylase system to prevent contamination by carryover of amplimers. in addition, the inclusion of an internal control in rt pcr assays is highly desirable to monitor for false-negative results due to inefficient nucleic acid extraction, cdna synthesis, or amplification. during outbreaks of avian influenza, the detection of subtype-specific antibodies is particularly important for epidemiological investigations. hemagglutination inhibition (hi) assays are the gold standard for detection of antibodies against human influenza viruses. however, their usefulness for detection of antibodies against avian viruses in mammalian species, including humans, seems limited (beare and webster, ; hinshaw et al., ; kida et al., ) . several studies have shown a failure to detect hi antibodies against avian viruses in mammals, even in cases where infection was confirmed by virus isolation. possible reasons for this failure include poor immunogenicity of some avian viruses and lack of sensitivity to detect low titered or less avid antibodies induced by avian viruses (hinshaw et al., ; kida et al., ; lu et al., ; rowe et al., ) . it has been demonstrated that hi testing with subunit ha, but not with intact virus, could detect antibodies against an avian h n virus (lu et al., ) . however, neutralizing antibodies against this virus could readily be detected with intact virus. a direct comparison of hi testing with a microneutralization assay in h n -infected persons from the hong kong outbreak indeed showed the latter to be more sensitive . while an indirect elisa assay using recombinant ha from h n / showed at least equal sensitivity as the microneutralization assay, the specificity in adult sera was inferior, possibly due to the presence of crossreactive epitopes common to all has . based on these observations, neutralization assays are the methods of choice for detection of antibodies against avian viruses in humans. using these assays, it has been shown that the kinetics of the antibody response against h n virus in patients infected during the hong kong outbreak are similar to the primary response to human influenza viruses (katz et al., ) . neutralizing antibodies were generally detected or more days after the onset of symptoms and titers equal to or higher that : were observed or more days after onset. currently, two classes of drugs are available with antiviral activity against influenza viruses: inhibitors of the ion channel activity of the m membrane protein, amantadine and rimantadine, and inhibitors of the neuraminidase, oseltamivir, and zanamivir. the therapeutic efficacy of amantadine in human influenza is unclear due to a paucity of reliable clinical studies, but reductions of fever or illness by day have been observed in adults and children (nicholson et al., ) . major disadvantages of amantadine include neurotoxicity and a rapid development of drug resistance during treatment. resistance is conferred by single nucleotide changes resulting in amino acid substitutions at positions , , , , or of the m protein. rimantadine causes less neurological side effects but is not available in most parts of the world. although several h n -infected patients have been treated with amantadine during the h n outbreak in hong kong, the numbers were too small to draw any meaningful conclusions concerning its activity against this virus (yuen et al., ) . in vitro sensitivity testing of virus isolated from the first patient during this outbreak showed normal susceptibility to amantadine (subbarao et al., ) . strikingly, genotype z h n viruses isolated from poultry and humans in thailand and viet nam in invariably showed an amantadine-resistance conferring amino acid substitution at position of the m protein, indicating that amantadine treatment is not an option during the ongoing outbtreak in southeast asia puthavathana et al., ) . both oseltamivir and zanamivir have proven efficacy in the treatment of human influenza when started early during the course of illness, and are particularly effective as seasonal or postexposure prohylaxis (nicholson et al., ) . zanamivir has poor oral availability and is therefore administered by inhalation, which has limited its use in the elderly and may induce bronchospasm. oseltamivir can be given orally. the development of drug resistance during treatment has been reported for both drugs and is associated with mutations in the active site of neuraminidase or in the hemaglutinin. the latter mutations decrease the affinity of ha for the cellular receptor, thereby obviating the need for neuraminidase to escape the cells. data on the efficacy of neuraminidase inhibitors in avian influenza virus are scarce. the h n strains implicated in the hong kong outbreak were susceptible in vitro to oseltamivir and zanamivir (govorkova et al., ; leneva et al., ) . oral oseltamivir and topical zanamivir also showed therapeutic and protective activities against hong kong h n isolates in murine animal models (gubareva et al., ; leneva et al., ) . recent murine studies suggest that, perhaps due to higher virulence, higher doses of oseltamivir and longer durations of treatment are necessary to achieve antiviral effects in mice against h n strains causing the southeast asian outbreak since , when compared to the hong kong h n strain (yen et al., ) . oseltamivir treatment has been given to several h n infected patients, but no conclusions can be made concerning its efficacy. however, the timing of antiviral treatment may not have been optimal in many cases of avian influenza so far. beneficial effects of antiviral treatment in human influenza are optimal when started within h after onset of the illness. during the h n outbreak in viet nam in , h n infected patients were admitted days or later after onset of symptoms (tran et al., ) . earlier recognition of avian influenza in humans may improve the efficacy of antiviral treatment. while several h n -infected patients have received steroids in addition to oseltamivir, the potential benefits of this need formal evaluation in clinical studies (tran et al., ) . considering the observed cytokine dysregulation in h n -infected animals and humans, a beneficial effect of immunomodulating agents could be hypothesized and perhaps requires further study. finally, neutralizing monoclonal antibodies have been shown effective in treating established influenza a virus infection in mice with severe combined immunodeficiency (palladino et al., ) . although mice are not men, this strategy deserves attention in the treatment of a severe illness such as influenza h n . birds infected with avian influenza excrete large amounts of virus in feces and other secretions, which contaminate the direct environment, such as dust, soil, water, cages, tools, and other fomites. avian influenza virus may remain infectious in soil, water, or contaminated equipment for weeks to months, depending on the temperature and humidity (i.e. longer in colder climates). illness in birds caused by highly pathogenic avian influenza viruses results in systemic replication and the presence of infectious virus in their eggs and many tissues and organs. transmission of avian influenza viruses between birds occurs directly or indirectly through contact with fecally contaminated aerosols, water, feed, and other materials. birdto-human transmission likely occurs via the same route, i.e. direct contact with birds or contaminated fomites. most, but not all human infections with avian influenza viruses involved handling of affected poultry or direct exposure to live poultry in the week before onset of the illness (koopmans et al., ; mounts et al., ; tran et al., ) . case-control studies during the h n outbreak in hong kong identified visiting a stall or market selling live poultry during the week before the illness as a risk factor, whereas eating or preparing poultry products were not (mounts et al., ) . in cases in which no apparent direct exposure to poultry could be identified, contact with contaminated environment, such as water, has been suggested (de jong et al., ) . of note, it has been shown that ducks infected by the currently circulating h n strain in southeast asia remain healthy but excrete large amounts of virus for prolonged periods of time (hulse-post et al., ) . since water in ponds and canals in which large flocks of ducks reside, is widely used for bathing and drinking in rural areas of many southeast asian countries, it may not be unlikely that such water represents a source of transmission when contaminated by infected ducks. in fact, contact with contaminated water is regarded as the most important mode of transmission between aquatic birds. a limited number of possible human-to-human transmissions of influenza h n have been reported, which involved prolonged, close and unprotected contact with infected patients (katz et al., ; koopmans et al., ; ungchusak et al., ) . similar to human influenza, droplet and contact transmission are probably the most effective means of transmission of avian influenza virus between humans, should the virus acquire the ability for efficient spread, but airborne transmission remains a possibility. the occurrence of diarrhea in h n -infected patients, which may contain infectious virus, represents a potential non-respiratory route of transmission, which needs to be considered in infection control practices (apisarnthanarak et al., ; de jong et al., ; tran et al., ) . data concerning excretion patterns and periods of potential infectivity are lacking for human infections with avian influenza viruses. based on exposure histories, the incubation time for human h n -infections has been estimated - days, but it is not known whether excretion of virus occurs during this time (tran et al., ; yuen et al., ) . based on the current (lack of) knowledge, infection control measures during contact with potentially infected birds or environment, or with patients with suspected or confirmed infection should prevent contact, droplet, and airborne transmission. these measures include mask (preferably high efficiency masks, with surgical masks as a second alternative), gown, face shield, or goggles and gloves. the efficacy of neuraminidase inhibitors as seasonal or postexposure prohylaxis against human influenza is high (nicholson et al., ) . offering prophylactic treatment to potentially exposed people in the setting of a poultry outbreak of avian influenza, as has been done during h -outbreaks in the netherlands and canada (koopmans et al., ; tweed et al., ) , is rational but hardly feasible during the ongoing outbreak in southeast asia for logistical and financial reasons. postexposure prophylaxis to unprotected healthcare workers and close contacts of infected patients is advisable. the potential use of specific monoclonal antibodies for prophylaxis warrants further investigation. eliminating the source of infection, i.e. infected birds, remains the most effective infection control measure. culling of all infected poultry have proven succesful during avian influenza outbreaks in hong kong, the netherlands and canada (chan, ; koopmans et al., ; tweed et al., ) . however, considering the geographic extensiveness of the outbreak in southeast asia, the different farming practices, and the reported h n infections in migratory birds (chen et al., ) , it seems very unlikely that culling of poultry alone will contain the outbreak in that region. the bulk of human influenza vaccines are produced from inactivated viruses grown in embryonated eggs. vaccine production against highly pathogenic avian influenza viruses is complicated because of the requirement for high biosafety containment facilities, and the difficulty, in some cases, to obtain high virus yields in embryonated eggs because of the virus' pathogenicity (stephenson et al., ; wood and robertson, ) . several other approaches have been used in an attempt to overcome these obstacles, including the use of reverse genetics techniques, generation of recombinant hemagglutinin, dna vaccination and the use of related apathogenic h viruses with and without different adjuvants (nicholson et al., ; stephenson et al., ; webby et al., ; wood and robertson, ) . experimental h n vaccines in which important virulence determinants were altered using plasmid-based reverse genetics, have shown protective efficacy to homologous and heterologous h strains in animal models and may prove an attractive approach (li et al., ; lipatov et al., ; takada et al., ) . studies in humans using an h n vaccine developed from a apathogenic avian virus showed high rates of seroconversions to the vaccine strain and heterologous h n strains after three doses, but only when the vaccine was given with the adjuvans mf . in animal models, baculovirusderived recombinant h vaccines were immunogenic and protective, but results in humans were disappointing even when using high doses (crawford et al., ; treanor et al., ) . h dna vaccines protected mice from infection by homologous, but not by heterologous h n viruses (epstein et al., ; kodihalli et al., ) . the increasing frequency of outbreaks with highly pathogenic avian influenza viruses among poultry and direct transmission of these viruses to humans, culminating in the ongoing extensive h n outbreak in southeast asia, has ignited grave concerns about an imminent influenza pandemic. indeed, two of three prerequisites for a human pandemic have been met in the southeast asian h n outbreak: the emergence of an antigenically novel strain to which the population has no immunity, and the transmission of this strain to humans in whom it can cause severe disease. to date, there is fortunately no evidence of efficient spread of h n virus between humans, but continued circulation of this strain, which now has reached levels of endemicity among poultry in several southeast asian countries, increases the opportunity to adapt to humans through mutation or genetic reassortment in humans or intermediate mammalian hosts. as suggested by the "spanish flu" pandemic of , extremely high transmissability is no prerequisite for a severe pandemic killing tens of millions of people, and as shown by the severe acute respiratory syndrome (sars) virus epidemic in , viruses can rapidly spread across the globe in the current age of intense global travel. as a consequence of all this, pandemic preparedness has become an important issue worldwide. pandemic plans, which include stock-piling of antivirals and candidate vaccines, are being developed by an increasing number of countries worldwide, and alternative methods for rapid vaccine production and potential methods enabling dose reduction of vaccines are increasingly propagated (schwartz and gellin, ; stephenson et al., ; webby et al., ; webby and webster, ; wood and robertson, ) . notwithstanding the importance of these efforts to prepare for a possible h n pandemic, more structural and longer term global efforts are needed to allow for early recognition of novel influenza viruses or other emerging pathogens infecting humans in the future. in , a who global agenda for influenza surveillance and control has been adopted, of which the main objectives are to strengthen surveillance, improve knowledge of the disease burden, increase vaccine use, and accelerate pandemic preparedness (stohr, ) . it is essential that these objectives are increasingly focused on the southeast asian region, which has been the source of previous pandemics and is the epicentre of the current pandemic threat. many southeast asian countries currently lack the expertise, financial means, and infrastructure for human and animal diagnostics and surveillance. global investments to improve public health care infrastructures and laboratory facilities, and to transfer clinical, epidemiological, and technical knowledge to these countries are much needed (hien et al., ) . the window of opportunity in the era of global travel is narrow. local capacity, and less dependence on foreign laboratories and expertise, will allow for earlier recognition and quicker responses to epidemics. in addition, local availability of clinical, scientific, and laboratory capacity facilitates and expedites clinical, virological, and epidemiological analyses needed to optimize outbreak control, infection control, and clinical managment. it also guarantees the timely availability of virus strains for monitoring virus evolution and planning of vaccines by reference laboratories. such global investments to enhance local infrastructure and expertise will increase the chances of success of containing an influenza pandemic at the source by antiviral prophylaxis and other preventive measures suggested by recent mathematical modelling studies (ferguson et al., ; longini et al., ) . seroprevalence of anti-h antibody among thai health care workers after exposure to avian influenza (h n ) in a tertiary care center sequence of the pandemic influenza virus nonstructural gene (ns) segment and characterization of recombinant viruses bearing the ns genes evolution of the h influenza virus hemagglutinin from human and nonhuman hosts replication of avian influenza viruses in humans risk of influenza a (h n ) infection among poultry workers continued circulation in china of highly pathogenic avian influenza viruses encoding the hemagglutinin gene associated with the h n outbreak in poultry and humans outbreak of avian influenza a(h n ) virus infection in hong kong in the evolution of h n influenza viruses in ducks in southern china avian flu: h n virus outbreak in migratory waterfowl induction of proinflammatory cytokines in human macrophages by influenza a (h n ) viruses: a mechanism for the unusual severity of human disease? studies of h n influenza virus infection of pigs by using viruses isolated in vietnam and thailand in human disease from influenza a (h n ) thailand human influenza a h n virus related to a highly pathogenic avian influenza virus receptor specificity in human, avian, and equine h and h influenza virus isolates influenza virus strains selectively recognize sialyloligosaccharides on human respiratory epithelium; the role of the host cell in selection of hemagglutinin receptor specificity baculovirus-derived hemagglutinin vaccines protect against lethal influenza infections by avian h and h subtypes fatal avian influenza a (h n ) in a child presenting with diarrhea followed by coma dna vaccine expressing conserved influenza virus proteins protective against h n challenge infection in mice strategies for containing an emerging influenza pandemic in southeast asia characterization of a novel influenza a virus hemagglutinin subtype (h ) obtained from black-headed gulls avian influenza a virus (h n ) associated with human conjunctivitis and a fatal case of acute respiratory distress syndrome specification of receptor-binding phenotypes of influenza virus isolates from different hosts using synthetic sialylglycopolymers: non-egg-adapted human h and h influenza a and influenza b viruses share a common high binding affinity for -sialyl(n-acetyllactosamine) the structure and receptor binding properties of the influenza hemagglutinin cellular transcriptional profiling in influenza a virus-infected lung epithelial cells: the role of the nonstructural ns protein in the evasion of the host innate defense and its potential contribution to pandemic influenza comparison of efficacies of rwj- , zanamivir, and oseltamivir against h n , h n , and other avian influenza viruses emergence of multiple genotypes of h n avian influenza viruses in hong kong sar h n influenza: a protean pandemic threat molecular characterization of h n influenza viruses: were they the donors of the "internal" genes of h n viruses in hong kong? characterization of influenza a/hongkong/ / (h n ) virus in a mouse model and protective effect of zanamivir on h n infection in mice avian influenza-a challenge to global health care structures replication of avian influenza a viruses in mammals role of domestic ducks in the propagation and biological evolution of highly pathogenic h n influenza viruses in asia molecular basis for the generation in pigs of influenza a viruses with pandemic potential antibody response in individuals infected with avian influenza a (h n ) viruses and detection of anti-h antibody among household and social contacts avian-to-human transmission of the pb gene of influenza a viruses in the and pandemics avian influenza h n in tigers and leopards potential for transmission of avian influenza viruses to pigs enhanced virulence of influenza a viruses with the haemagglutinin of the pandemic virus dna vaccine encoding hemagglutinin provides protective immunity against h n influenza virus infection in mice transmission of h n avian influenza a virus to human beings during a large outbreak in commercial poultry farms in the netherlands avian h n influenza in cats characterization of highly pathogenic h n avian influenza a viruses isolated from south korea efficacy of zanamivir against avian influenza a viruses that possess genes encoding h n internal proteins and are pathogenic in mammals the neuraminidase inhibitor gs (oseltamivir phosphate) is efficacious against a/hong kong/ / (h n ) and a/hong kong/ / (h n ) influenza viruses genesis of a highly pathogenic and potentially pandemic h n influenza virus in eastern asia recombinant influenza a virus vaccines for the pathogenic human a/hong kong/ (h n ) viruses lack of h n avian influenza transmission to hospital employees neurovirulence in mice of h n influenza virus genotypes isolated from hong kong poultry in efficacy of h influenza vaccines produced by reverse genetics in a lethal mouse model containing pandemic influenza at the source failure to detect hemagglutinationinhibiting antibodies with intact avian influenza virions the surface glycoproteins of h influenza viruses isolated from humans, chickens, and wild aquatic birds have distinguishable properties avian influenza a viruses differ from human viruses by recognition of sialyloligosaccharides and gangliosides and by a higher conservation of the ha receptor-binding site human and avian influenza viruses target different cell types in cultures of human airway epithelium transmissibility of pandemic influenza encephalitis and encephalopathy associated with an influenza epidemic in japan case-control study of risk factors for avian influenza a (h n ) disease influenza a pandemics of the th century with special reference to : virology, pathology and epidemiology virus-neutralizing antibodies of immunoglobulin g (igg) but not of igm or iga isotypes can cure influenza virus pneumonia in scid mice re-emergence of fatal human influenza a subtype h n disease molecular characterization of the complete genome of human influenza h n virus isolates from thailand origin and evolution of the "spanish" influenza virus hemagglutinin gene evidence of an absence: the genetic origins of the pandemic influenza virus receptor binding properties of human and animal h influenza virus isolates receptor determinants of human and animal influenza virus isolates: differences in receptor specificity of the h hemagglutinin based on species of origin single amino acid substitutions in influenza haemagglutinin change receptor binding specificity detection of antibody to avian influenza a (h n ) virus in human serum by using a combination of serologic assays on the origin of the human influenza virus subtypes h n and h n avian influenza h n and healthcare workers vaccination strategies for an influenza pandemic cross-reactivity to highly pathogenic avian influenza h n viruses after vaccination with nonadjuvanted and mf -adjuvanted influenza a/duck/singapore/ (h n ) vaccine: a potential priming strategy confronting the avian influenza threat: vaccine development for a potential pandemic structure of the uncleaved human h hemagglutinin from the extinct influenza virus the global agenda on influenza surveillance and control reemerging h n influenza viruses in hong kong in are highly pathogenic to ducks characterization of an avian influenza a (h n ) virus isolated from a child with a fatal respiratory illness influenza-associated encephalopathy in japan avirulent avian influenza virus as a vaccine strain against a potential human pandemic neurotropism of the hong kong h n influenza virus in mice initial genetic characterization of the "spanish" influenza virus pathology of fatal human infection associated with avian influenza a h n virus avian influenza a (h n ) in patients in vietnam safety and immunogenicity of a recombinant hemagglutinin vaccine for h influenza in humans human illness from avian influenza h n , british columbia influenza h n replication sites in humans probable person-to-person transmission of avian influenza a (h n ) responsiveness to a pandemic alert: use of reverse genetics for rapid development of influenza vaccines are we ready for pandemic influenza? evolution and ecology of influenza a viruses characterization of h n influenza viruses that continue to circulate in geese in southeastern china cumulative number of confirmed human cases of avian influenza a/(h n ) reported to who from lethal virus to life-saving vaccine: developing inactivated vaccines for pandemic influenza latex agglutination test for monitoring antibodies to avian influenza virus subtype h n genetic characterization of the pathogenic influenza a/goose/guangdong/ / (h n ) virus: similarity of its hemagglutinin gene to those of h n viruses from the outbreaks in hong kong virulence may determine the necessary duration and dosage of oseltamivir treatment for highly pathogenic a/vietnam/ / (h n ) influenza virus in mice clinical features and rapid viral diagnosis of human disease associated with avian influenza a h n virus we thank the staff of the hospital for tropical diseases ho chi minh city, the health service of ho chi minh city and the ministry of health, viet nam. menno de jong is funded by the wellcome trust, uk. key: cord- -qwaoe du authors: walline, joseph harold title: quarantine wristbands, face masks, and personal freedom in hong kong date: - - journal: j emerg med doi: . /j.jemermed. . . sha: doc_id: cord_uid: qwaoe du nan what is the relationship between freedom and health in an era of viral crisis? i write to share my perspective on responses to the coronavirus disease (covid- ) pandemic as an american emergency physician living in hong kong who was recently required to wear a tracker wristband and subjected to mandatory home quarantine. i did my residency training in new york city and have watched with dismay as the covid- pandemic has engulfed my former home and forced many colleagues to work on the frontlines with inadequate supplies of personal protective equipment. what hopes might hong kong's approach to infection control offer for new york and other cities in the united states? i returned to hong kong on march , the first day of the city's mandatory -day home quarantine policy for all incoming travelers. this home quarantine policy was part of a broader infection control system in hong kong involving universal hospitalization of all positive covid- cases, exhaustive social contact tracing, and selective quarantining of high-risk individuals. despite a recent ban on face coverings enacted last october in response to political protests, wearing face masks has also become a universal social practice in hong kong since the first covid- patient was diagnosed here on january ( ). not surprisingly, everyone i encountered on my arriving flight and throughout the airport was wearing a face mask, and some even donned hazmat suits or rain ponchos. after recording my body temperature, no fewer than three different centre for health protection (chp) workers asked me about my recent travel history. compare this with my entry into the united states a week earlier at los angeles international airport (lax), where no temperature checks or forms were provided and i was asked only a single question prior to being admitted to the country: ''you haven't been to china recently, have you?'' i also felt social pressure to remove my face mask to avoid attracting unwanted attention while going through passport control at lax (over weeks prior to the centers for disease control's about-face recommendation on april that all americans wear cloth face masks) ( ) . when i arrived in hong kong, all adults and children older than age years who had traveled anywhere other than taiwan, macau, and mainland china during the standard incubation period were required to undergo a mandatory -day home quarantine (this has since been upgraded to include mandatory testing) ( ). i was instructed to fill out a quarantine order form in duplicate, which requested a home address and mobile phone number. i was then fitted with a ''quarantine tracker'' wristband-a strip of waterproof paper printed with a unique serial number and matching qr code and affixed around my wrist with a plastic clasp (figure ). the chp officer instructed me to expect a short message service (sms) notice on my mobile phone for guidance on my next steps. the sms finally arrived on the second day, instructing me to download and install the ''stay home safe'' application on my mobile phone. after scanning my qr code, the app then informed me i would have minute to walk slowly around the perimeter of my home to mark the boundaries of my confinement in ''cellular'' space. unfortunately, the app stopped tracking after seconds, leaving me midway through my perambulation with my bedroom unscanned. this turned out to be quite significant: every time i ventured out of the scanned zone for the next days, this triggered a loud warning and i was given seconds to tap ''validate'' on the app and confirm my presence at the place of quarantine by scanning the qr code on my wristband. home quarantine violators risked being sent to mandatory government quarantine camps, a maximum fine of , hong kong dollars (hkd), and imprisonment for months ( ). tracker wristbands, monitoring apps, and threats of law enforcement seem anathema to most americans and other citizens of western liberal democraciesperhaps too high a price to pay for public health. yet i would argue that this dichotomy between freedom and health is a false one. i returned to hong kong knowing that i would be placed under quarantine for a defined period. i willingly accepted this mandatory confinement with the knowledge that i would be released in days (or if i fell ill, that i would be guaranteed full medical treatment). people in the united states and europe are experiencing even greater infringements on personal liberty, as national lockdowns and shelter-in-place orders continue to get extended. in hong kong, the quarantine wristbands are a sign of a functioning public health system-even if they are merely strips of paper. by quarantining the most at-risk individuals (including travelers and close contacts), hong kong's approach enables most of the population to maintain freedom of movement-including the confinees after their -day stint. after completing my home quarantine, i was able to venture out from my apartment (with my mask on)-confident in being disease free and that most of those around me were also disease free. i am not saying that hong kong's situation is ideal, as the city faces significant political problems that are simply on hold during the pandemic. but hong kong's experiments with quarantine provide important lessons for other places currently facing lockdowns. the logic in the united states focuses on ''flattening the curve'' and avoiding overwhelming an already overburdened medical system. but this is not enough. in hong kong, quarantining works in tandem with a broader public health system that offers universal health care regardless of employment status, and an integrated set of infection control policies. by quarantining the few for a set period (the -day incubation period), the many can go about daily life with the relative assurance that they will likely not encounter someone infected by covid- . i hope that the extreme measures taken elsewhere will not just ''flatten the curve,'' but also allow time to ramp-up public health responses. i believe that a functioning public health system is what will ultimately secure both freedom and health. government of the hong kong special administrative region. chp announces latest situations and measures on imported cases of novel coronavirus infection recommendation regarding the use of cloth face coverings government of the hong kong special administrative region. dh strengthens health quarantine and testing arrangements for inbound travellers government of the hong kong special administrative region. compulsory quarantine of persons arriving at hong kong from foreign places regulation gazetted clockwise from top right: quarantine wristband, quarantine app detection-in-process, short message service (sms) received on the last day of quarantine, and the ''stay home safe key: cord- -mpr xb a authors: petersen, eskild; wasserman, sean; lee, shui-shan; go, unyeong; holmes, allison h.; abri, seif al; mclellan, susan; blumberg, lucille; tambyah, paul title: covid- –we urgently need to start developing an exit strategy date: - - journal: int j infect dis doi: . /j.ijid. . . sha: doc_id: cord_uid: mpr xb a abstract aim the purpose of this perspective is to review the options countries have to exit the draconian “lock downs” in a carefully staged manner. methods experts from different countries experiencing corona virus infectious disease (covid- ) review evidence and country specific approaches and results of their interventions. results three key factors are important: . reintroduction from countries with ongoing community transmission; . the need for extensive testing capacity and widespread community testing, and . adequate supply of personal protective equipment, ppe, to protect health care workers. lifting social distancing is discussed at length. how to open manufacturing, construction and logistics. the opening og higher educational institutions and schools. the use of electronic surveillance is discussed. conclusion each country has to decide what is the best path forward. however, we can learn from each other and the approach is in reality very similar. with the sars-cov- pandemic passing one million ill people ( , , confirmed cases and reported deaths (who sit rep th april) most countries are occupied with controlling the outbreak. the economic consequences are enormous. the world trade organization (wto) estimate that "commerce could shrink up to % and warns against s-style protectionism" [wto ]. with no vaccine and no proven effective treatment, the tools available are limited to social distancing which include quarantine and travel restrictions. these tools are the same as were available during the black death due to plague in europe in the th century although modern molecular diagnostics and electronic surveillance have modified them slightly. with no manual to follow most countries have taken a broad approach to slow down the spread of the infection, trying to "flatten the curve" to prevent overwhelming the health care systems by enforcing tight restrictions on population movements. this strategy has effectively "shut own" society and reduced economic activity by closing offices and manufacturing plants, closing schools, restricting mobility in public places, closing nonessential shops, restricting traffic (road, air and sea) and closing borders. this comes with a heavy socio-economic price, particularly in low-and-middle income countries with limited capacity to absorb prolonged national 'lockdowns'. many companies have or will file for government support or bankruptcy. unemployment is rapidly increasing, with devastating consequences on the lives of vulnerable populations, particularly in lowand middle-income countries (lmic). it is important to plan for the reactivation of society, restarting work and production, opening up for travels and education. no one knows the future and there have been speculations of "a second wave" which so far is conjectural but may well happen. a strategy or 'roadmap' for deescalating the enforced physical distancing based on epidemiological indicators is needed to inform citizens and policy makers. this review discusses from an epidemiological and medical point of view how strict isolation measures could gradually be lifted. the medical profession must lead the way out of the pandemic just as we shaped the response at the beginning. an evaluation version of novapdf was used to create this pdf file. purchase a license to generate pdf files without this notice. page of j o u r n a l p r e -p r o o f the post peak period -the "opening phase" what is the "post peak period"? there is no clear definition but most experts providing opinions to the media agree that having a plateau of cases or hospital admissions for two weeks signals that the transmission has stabilized and hospitals are able to treat all patients requiring hospitalization for covid- without resorting to crisis standards of care [zhang j et al. ]. this is the time when opening up society should be considered. however, because most of the population has not yet been exposed there are concerns that, with minimal but ongoing local transmission, new clusters might escape into the community triggering a second wave of infections [leung k et al., ]. in the "post peak" period it will be important to classify the epidemiological situation to increase the understanding of and target transmission and we suggest the following, adapted from the who [who march ] (table ) . there are important lessons from countries such as china and korea that managed to control the outbreak after experiencing a peak in the first-wave epidemic; taiwan [wang et al. ] and macau [lo et al. ] which managed to keep case counts low; and places where despite initial control there has been a resurgence such as singapore and hong kong. the experience from these countries point to three main challenges: . reintroduction from countries with ongoing community transmission (still in the outbreak phase) may initiate a new outbreak in the susceptible population. . the need for extensive testing capacity and widespread community testing to identify new cases as early as possible, coupled with effective contact tracing and isolation ability. . the importance of adequate supply of personal protective equipment, ppe, to protect health care workers. the outbreak has demonstrated how easily a respiratory infection can spread across borders. if countries open up for travel before widespread sars-cov- immunity there need to be interventions to reduce risk of transmission from travelers with few or no symptoms. an evaluation version of novapdf was used to create this pdf file. purchase a license to generate pdf files without this notice. page of j o u r n a l p r e -p r o o f post-arrival quarantine has been applied effectively by south korea, but this is impractical and cannot be implemented in most countries. we believe that the international health regulation, ihr, an agreement between countries including all who member states to work together for global health security, has an important role to play in enforcement of more targeted travel restrictions [ihr ]. under the ihr, using a mechanism similar to the yellow fever immunization certificate requirement, travelers could be asked to provide proof of previous infection, and therefore immunity, by having sars-cov- specific igg antibodies [petersen et al. ] . seronegative travelers could be asked undergo rapid testing (antigen or pcr in the airport pre-departure). however, rapid testing technologies are not yet available for routine implementation [petherick a et al. ]. in hong kong, truck drivers are required from the end of this week ( th april ) to produce evidence of a "sars-cov- negative medical certificate" when they cross the hong kong -mainland border, as required by the chinese government; these ~ , drivers play an important role of ensuring that hong kong have food and commodities during the "lockdown". south korea imposed two weeks mandatory quarantine on all travelers entering the country from the st april; persons with previous infection as documented by positive serology are exempt. this is analogous to healthcare workers who are required to document immunity to varicella, measles, mumps, rubella and hepatitis b before working in most healthcare institutions. risk-based approaches to travel restrictions could also be considered. for example, travel restrictions could be eased between countries "past the peak" with local transmission at low levels. for instance, travels between germany and china could be opened under certain conditions that persons from third countries with high transmission rates would not be eligible for. another approach could be to open travel from countries with good surveillance systems, transparent reporting, and few local cases where risk of importing infected cases would be low. opening aviation routes would require agreement between the two countries for direct flights. an evaluation version of novapdf was used to create this pdf file. purchase a license to generate pdf files without this notice. page of j o u r n a l p r e -p r o o f lifting the general restrictions on mobility and social distancing allowing business to open, opening schools and higher education institutions, staring manufacturing and allowing travel should be done after peak incidence. however, circulating virus has not disappeared, and resurgence remains a possibility. determining the rate at which mild disease is spreading in the community is critically important to inform shifts between containment and mitigation strategies. after de-escalation of enforced physical distancing by closing shops and work places, community-based symptom screening and testing must be made widely available to allow early identification of new cases. this will only be effective if supported by contact tracing, quarantine, and isolation that need supervision by public health authorities. in low-andmiddle income countries it will be essential to provide facilities for quarantine and isolation for people unable to safely do so in their homes. in the opening phase access to testing on broad indications must be available to all people to allow identification of new cases and clusters as early as possible. this would ideally be supported by point of care tests that are accurate and reliable. there should also be strong systems of surveillance for influenza-like illness, mortality rates, and sick leave. public health authorities must be properly staffed and equipped. a recent study from california testing patients with respiratory symptoms found that % of influenza-negative were sars-cov- pcr positive [zwald ml ] and such testing at sentinel sites is an important tool to keep track of community transmission. thus, public health capabilities for case identification and isolation must be expanded probably permanently; tools can include physical inspection or use of electronic devices, such as mobile phone-based surveillance and point of care tests as used in taiwan, korea and oman, summarized in table . the examples from korea, singapore and hong kong show that the virus will re-emerge if strict control measures are relaxed. the closure of all social activities and confining people at home has a profound effect on the economy and should only be maintained until other, an evaluation version of novapdf was used to create this pdf file. purchase a license to generate pdf files without this notice. containment efforts could be focussed on populations at highest risk from infection, including people over years old, people living in care institutions, and those with chronic medical conditions. these groups would need to be identified and supported to restrict their movements and practice social distancing for a longer period than the rest of society. communications about such an approach will be critical as the public currently has a strong negative attitude towards any mention of "herd immunity". during times of eased restrictions working from home -"teleworking" -should still be encouraged, and social gatherings discouraged. strategies to reduce workplace transmission include daily declarations of being symptomfree by all staff members, and where feasible, screening of staff by rt-pcr or even serology immediately after lifting of enforced quarantine, but the need to screen everyone at a work place before it opens up must be determined individually. this may be particularly important in higher risk industries such as the hospitality sector (tourists and hotels) and aviation or others with high degrees of interaction with vulnerable populations. the occupational health service will be important when manufacturing and construction industries open to keep a very close surveillance on employees and test and quarantine anyone with symptoms pending test results. similarly to targeted travel restrictions, opening up shops, offices, school and factories could be preceded by rt-pcr testing of asymptomatic or oligosymptomatic persons and/or introduction of widespread serological testing to confirm immunity prior to removal of individual quarantine. this would require massive mobilisation of resources and is unlikely to be feasible in lmics in the short term. it is critical to have communities as partners understanding the need for restriction even while some parts of society start working again. the higher the buy-in and quality of response in every locality, the better the outcome. universal masking has been proposed as an additional strategy for reducing community transmission. a surgical masks may reduce risk of community transmission from infected people [leung cc et al. ; chan kh et al. ]. this appears to have been effective in an evaluation version of novapdf was used to create this pdf file. purchase a license to generate pdf files without this notice. page of j o u r n a l p r e -p r o o f countries such as taiwan and south korea and parts of italy where mandatory mask wearing was implemented, although independent impact is difficult to assess. the who has recently stated that "the use of a medical mask can prevent the spread of infectious droplets from an infected person to someone else and potential contamination of the environment by these droplets" [who e april] and opening workplaces and ask employees to wear a face mask -surgical mask or equivalent -for two weeks after opening is an option which must be discussed with the occupational health service. lombardy in italy imposed mandatory face masks in public places [the guardian ] . we do not know if this will prevent person-to-person spread to the same extent as the closure of shops, factories, educational institutions and offices, but it make sense that masks (including non-medical) will reduce expulsion of large infectious droplets as stated by the who, thus reducing the risk of transmission in public spaces. in china, shops, restaurants, bars, and offices are opening. manufacturing activity is picking up and traffic starts to flow. three-quarters of china's workforce was back on the job as of march, according to one company's estimate. wuhan, where the covid- pandemic originated, is lagging, as is the rest of hubei province-but even there, the lockdown was lifted the th april [normille d ]. the impact of this has yet to be determined. covid- clusters much more in families and households and social contacts of those households (fan j et al. ). more granular geographical information is needed for effective contact tracing, for instance using geographical information systems (gis). the lesson from south korea is that tracking of cases and contacts via modern digital technology to apply focused testing can control community transmission without enforced distancing [korean cdc ] . after identifying a case, contacts will be asked to self-quarantine and monitored by appropriate digital technology. random sampling would help to estimate the number of mild or asymptomatic cases and inform about the true attack rate in the population. an evaluation version of novapdf was used to create this pdf file. purchase a license to generate pdf files without this notice. a well-established and strong core program of infection prevention and control within the healthcare system is central to preparedness and responsiveness. it will also need to be maintained as a priority in the recovery phase of healthcare systems and national exit strategies. as the number of covid- inpatients diminishes and the proportion of inpatients that are covid- naïve rises again, the likelihood of potential nosocomial infection may increase. it is important that there are established hospital surveillance systems that can capture nosocomial infections rapidly and prevent the generation of hospital outbreaks and further waves of transmission. hand hygiene and environmental hygiene must be considered as underpinning priorities in protecting healthcare staff, and efforts must be made to promote social distancing in health care settings. the sars epidemic in hong kong demonstrated how vulnerable front line health care workers (hcws) are. protecting hcws is a major task and sufficient personal protective equipment (ppe) must be available [cheng vcc et al. ]. the protection of hcws and support staff is critical, and the resilience of healthcare systems is dependent on sustaining their safety and their trust. in covid- in comparison to sars, particular attention is needed to ensure that hcws seeing individuals at the earliest stages in the disease are also well protected, this would include those working in the community and in residential and care homes. ppe guidelines for healthcare systems need to be clearly communicated, understood, supported by staff and based on best evidence. however, the ppe recommended in any guidance must have the necessary supporting supply chain well defined and clearly mapped, along with the appropriate logistics and the capacity to maintain this. without continuous adequate, appropriate ppe provision for hcws and support staff, their sustained commitment and trust required for an effective exit strategy may be lost [cheng vcc et al. ; who ipc ] . up to the th march, singapore had reported a total of cases with deaths. the ministry of health (moh) had developed a local case definition already by the nd of january and sars-cov- real-time polymerase chain reaction (rt-pcr) laboratory testing capacity was scaled up rapidly to all public hospitals in singapore to handle , tests a day. all contacts were assessed by telephone for fever or respiratory symptoms by public health officials during the quarantine or monitoring period, thrice daily for close contacts and once daily for contacts at lower risk. in late january the following groups were tested for sars-cov- : ) all hospitalized patients with pneumonia (later expanded to include patients with pneumonia evaluated in primary care settings); ) icu patients with possible infectious causes as determined by the physician; ) patients with influenza-like illness at sentinel government and private primary care clinics included in the routine influenza surveillance network; and ) deaths from possible infectious causes [ng y et al. ]. despite the city state's strict contact-tracing, quarantining and travel restrictions, a second wave of infections from returning residents and local transmissions saw cases spike from to , in one month (scmp rd april). the initial part of the second wave of infections involves singapore residents returning from countries such as the united states and britain. an evaluation version of novapdf was used to create this pdf file. purchase a license to generate pdf files without this notice. page of j o u r n a l p r e -p r o o f the second wave also includes an increasing number of locally transmitted infections and cases with no known links to confirmed patients. in response to the second wave, the city state introduced stricter social distancing measures, barring the entry of all travellers closing bars and nightlife, and eventually introducing a strict lockdown in early april with schools, non-essential shops, places of worship etc. closed for a month as locally transmitted cases routinely exceeded a hundred a day. in hong kong, the first imported case of covid- was reported on jan. , two days before the lunar new year. from the last week of january the government had ordered closure of schools while most borders with mainland china were closed from the first week of february. between february and april control measures were stepped up. ordinance (cap ), compulsory quarantine and social distancing orders became enforced. quarantine covers all people including local citizens entering hong kong. social distancing regulations include prohibition of gathering of more than persons in public areas, restriction of number of customers and the occupancy of catering premises, closure of amusement game centres, bathhouses, fitness centers, bars and other entertainment places. there is no legal restriction on workplaces but the government has, since late january, mandated work-from-home arrangement for civil servants. however, vacation of workplaces affected not only the , -strong government staff-force but also employees of statutory bodies, non-government organizations as well as major businesses. as of april, confirmed cases of sars-cov- infection were reported in the -million population city, with deaths [government of hong kong ]. some % were imported cases or their contacts while local transmission especially dormitories with migrant workers accounted for the rest. over half of the non-imported cases could be traced back to their close contacts with reported local cases. there was marked increase of daily reports from less than in january/february to - since the second half of march, which was attributed to the return of local citizens following acceleration of the european outbreaks, and the scaling up of testing. the main local transmission clusters had occurred in a religious worship area and social activities including dinner gatherings and entertainment bars. transmission linked to contacts in workplace has so far been uncommon. universal masking an evaluation version of novapdf was used to create this pdf file. purchase a license to generate pdf files without this notice. page of j o u r n a l p r e -p r o o f in public areas and on public transport is a common sighting, and in fact forms part of the general hygiene advice. such practice is required by law for staff and people patronizing catering premises, as stipulated in the newly enacted legal regulation. while the epidemic appeared to be less severe than other cities/countries in the region, restrictions have continued to be tightened to guard against major outbreaks. taiwan enhanced covid- case finding by proactively seeking out patients with severe respiratory symptoms (based on information from the national health insurance (nhi) database who had tested negative for influenza and retested them for covid- found of cases. the toll-free number served as a hotline for citizens to report suspicious symptoms or cases in themselves or others; as the disease progressed, this hotline has reached full capacity, so each major city was asked to create its own hotline as an alternative. it is not known how often this hotline has been used. the government addressed the issue of disease stigma and compassion for those affected by providing food, frequent health checks, and encouragement for those under quarantine. this rapid response included hundreds of action items. taiwan citizens' household registration system and the foreigners' entry card allowed the government to track individuals at high risk because of recent travel history in affected areas. those identified as high risk (under home quarantine) were monitored electronically through their mobile phones. on january , the nha database was expanded to cover the past -day travel history for patients from china, hong kong, and macau. on february , the entry quarantine system was launched, so travelers can complete the health declaration form by scanning a qr code that leads to an online form, either prior to departure from or upon arrival at a taiwan airport. a mobile health declaration pass was then sent via sms to phones using a local telecom operator, which allowed for faster immigration clearance for those with minimal risk. this system was created within a -hour period. on february , the government announced that all hospitals, clinics, and pharmacies in taiwan would have access to patients' travel histories. an evaluation version of novapdf was used to create this pdf file. purchase a license to generate pdf files without this notice. south africa is an upper-middle income economy with a population of approximately million people and one of the highest inequality rates in the world. critical concerns are the large population of people living in densely populated peri-urban areas with poor social circumstances plus the high national prevalence of hiv and tb, which may interact with sars-cov- to cause more severe disease. in addition, south africa's health services are already overburdened with limited capacity to absorb a large influx of covid- patients. the first case of covid- was detected on march in a group of travelers from italy and the initial period of the epidemic was limited to imported cases and their contacts, occurring within a specific demographic of more middle class and relatively younger people. the government responded rapidly, announcing a national state of disaster on march after confirmed cases had been reported with evidence of local transmission (figure ). this initial public health response included travel bans from countries with high levels of community transmission and -day mandatory quarantine for all returning travelers from those countries; school closures; cancellation of gatherings of more than people; and expanding testing and isolation capacity. one week after these measures were implemented, and after case numbers had grown six-fold to cases, a strict national week lockdown beginning march was initiated, which prohibited all movement for citizens not involved in designated essential services "except under strictly controlled circumstances, such as to seek medical care, buy food, medicine and other supplies or collect a social grant." despite the profound impact of the lockdown on an already tenuous economy -estimated reduction in growth by . % translating into ~ % contraction of national gdp -the president announced a -week extension on april, following an apparent reduction in the average daily infection rate from % to %. critical challenges for transitioning to a risk-based containment strategy in south africa include limited testing capacity -currently , tests have been performed; matching the per-capita testing of south korea would require , tests -and lack of infrastructure to implement contact tracing and isolation for people living in dense peri-urban environments. an evaluation version of novapdf was used to create this pdf file. purchase a license to generate pdf files without this notice. each country has to decide how to open up society for work and social activities. a study comparing health care systems in hong kong, singapore and japan had three important conclusions [legido-quigley et al. ]. the first is that "integration of services in the health system and across other sectors amplifies the ability to absorb and adapt to shock". the second is that "the spread of fake news and misinformation constitutes a major unresolved challenge". finally, "the trust of patients, health-care professionals, and society as a whole in the government is of paramount importance for meeting health crises". while the surge of cases in these three countries may have altered the analysis somewhat, the general principles still apply. this is a new infection spreading in a nonimmune population and we have no manual -yet we have to take decisions. measures that can be used are summarized in table . as each country chooses its own path, we can learn from each other to determine the optimum approach that works in our setting. funding. the study received no funding table . a reopening of society should be staged according to the local situation restrictions lifted for a specific sector of the society. could be schools, could be certain manufacturing industries, construction industry. could be limited to low endemic areas only. observe for weeks, monitor hospital admissions, perform testing at sentinel sites and all persons with upper and lower respiratory tract infections. extend opening of manufacturing and construction industries open public transport but request face mask in public spaces open schools in more areas open international travels from selected countries, quarantine arrivals from high endemic countries or perform rapid dna test on arrival observe for weeks, monitor hospital admissions, perform testing at sentinel sites and all persons with upper and lower respiratory tract infections. open small shops and restaurants provided social distancing is maintained. open international travels from selected countries, quarantine arrivals from high endemic countries or perform rapid dna test on arrival. observe for weeks, monitor hospital admissions, perform testing at sentinel sites and all persons with upper and lower respiratory tract infections. open up for mass gatherings like football matches, religious gatherings etc. . . . . table . generic electronic surveillance system. the system use information from mobile phones or bracelets. the system is linked to a national electronic surveillance system and to the civil identification number and can be shared with other stakeholders such as police or public prosecution. an "isolation enforcement system" can provide supervision of location of persons in isolation or quarantine outside institutions. isolation tracking app isolation compliance crowdsensing when people in quarantine move out of the isolation facility mobile phone and/or bracelet app self reporting and symptoms analysis self reporting questionnaires translation and language support the bracelet is for a single-use purpose that makes it very cost-effective and will be able to measure the body temperature the system will allow authorities to supervise compliance with quarantine and isolation anti-temper -month battery life perform contact history by linking geographical location of sim card or bracelet risk assessment according to the number of people quarantined or isolated in a specific geographical location. an evaluation version of novapdf was used to create this pdf file. purchase a license to generate pdf files without this notice. table . principles can help countries to plot a way out of the shutdown. . consider easing restrictions when the case count has decreased after the peak, has been stable for weeks and the hospitals can cope with the number of serious cases. cases must be staged into imported, linked to known clusters and cases and unknown source. . expand testing for new and past infections by setting up sentinel testing sites, introduce testing stations in the community providing diagnostic tests to everyone with compatible symptoms and serological testing for surveillance of population immunity. introduce point-of-care (poc) testing when validated tests become available. . consider testing employees with nucleic acid tests and/or antibody test prior to return to work to find silent cases and recovered persons. this can be applied to schools also. in collaboration with the occupational health service establish sustainable workplace policies emphasizing infection control. . consider imposing the use of surgical or non-medical face masks whenever outside the household to reduce risk that persons with an unrecognized infection will contribute to transmission. this must be an adjunct to other ongoing social distancing interventions and hand hygiene. . continue to impose quarantine on arriving passengers from countries with active outbreaks. aim to develop a travel certificate for people with documented immunity with sars-cov- -specific antibodies to be exempt from quarantine rules. . maintain strong infection prevention measures in all health care institutions . the sarc-cov- virus will most probably be in our societies for a long time until we have a vaccine. flare ups, small outbreaks and clusters is expected and thus the public health care system must be developed to take care of new cases, rapidly perform case and contact follow up and ensure quarantine. thus, a permanent upgrade of the public system is needed. covid- epidemic: disentangling the re-emerging controversy about medical facemasks from an epidemiological perspective escalating infection control response to the rapidly evolving epidemiology of the coronavirus disease (covid- ) due to sars-cov- in hong kong epidemiology of novel coronavirus disease- in gansu province, china, . emerg infect dis. ; : . government of hong kong lombardy insists on face masks outside homes to stop covid- . angela giuffrida in orvieto and peter beaumont impact of school closures for covid- on the us healthcare workforce and net mortality: a modelling study middle east respiratory syndrome coronavirus outbreak in the republic of korea disease control and prevention. the updates of the covid- in the republic of korea epidemiology and case management team. contact transmission of covid- in south korea: novel investigation techniques for tracing contacts guideline for covid- response interrupting transmission of covid- : lessons from containment efforts in singapore are high-performing health systems resilient against the covid- epidemic? mass masking in the covid- epidemic: people need guidance first-wave covid- transmissibility and severity in china outside hubei after control measures, and second-wave scenario planning: a modelling an evaluation version of novapdf was used to create this pdf file. purchase a license to generate pdf files without this notice. impact assessment. the lancet evaluation of sars-cov- rna shedding in clinical specimens and clinical characteristics of patients with covid- in macau evaluation of the effectiveness of surveillance and containment measures for the first patients with covid- in singapore can china return to normalcy while keeping the coronavirus in check? the korean middle east respiratory syndrome coronavirus outbreak and our responsibility to the global scientific community covid- travel restrictions and the international health regulations -call for an open debate on easing of travel restrictions developing antibody tests for sars-cov- coronavirus singapore: to , infections in one month. what happened? rd the government of the republic of korea. tackling covid- . health, quarantine and economic measures: korean experience response to covid- in taiwan: big data analytics, new technology, and proactive testing operational considerations for case management of covid- in health facility and community. interim guidance who situation report- . st advice on the use of masks in the context of covid- . interim guidance. geneva th coronavirus disease (covid- ) technical guidance: infection prevention and control / wash. collection of documents an evaluation version of novapdf was used to create this pdf file trade set to plunge as covid- pandemic upends global economy evolving epidemiology and transmission dynamics of coronavirus disease outside hubei province, china: a descriptive and modelling study rapid sentinel surveillance for covid- table . classification of new cases during surveillance in the imported, i.e. likely infections abroad b. part of known cluster, or contact to known case c an evaluation version of novapdf was used to create this pdf file. purchase a license to generate pdf files without this notice all authors contributed equally to the text.an evaluation version of novapdf was used to create this pdf file. purchase a license to generate pdf files without this notice.page of j o u r n a l p r e -p r o o f key: cord- - mrbgwg authors: keck, frédéric title: birds as sentinels for pandemic influenza date: - - journal: biosocieties doi: . /biosoc. . sha: doc_id: cord_uid: mrbgwg nan how can animals send signals of future threats to humans? this question has always fascinated humans and anthropologists, but it gains a new meaning in the contemporary world of biosecurity where health issues are considered as security priorities and coming epidemics are the objects of anticipatory knowledge. understanding how non-humans are enroled in anticipatory knowledge and how this transforms their relations with humans is a key concern for social scientists. a microbiological article that is of particular interest to this body of scholarship was written in by shortridge, peiris and guan: "the next influenza pandemic: lessons from hong kong". published in the journal of applied microbiology, it addresses a broader audience and draws lessons from years of mobilisation against influenza as a public health concern. when microbiologists learn from history, as they have done for aids (dodier, ) , they write in the language of viruses. because of the high mutation rate of the flu virus, new forms of the disease constantly emerge and can become pandemic, as was the case in hong kong in . the question raised by shortridge et al is which flu virus was the candidate for the next pandemic and how it could be detected before spreading widely. for a 'global clinic' (king, ) it is necessary to know what candidate vaccines must be prepared for a future outbreak. however, we have learned from hong kong that stockpiling vaccines is not the only way to prepare for a pandemic. shortridge et al's article draws lessons not only from history but also from geography. being a british colony in , hong kong was the place where the last pandemic flu virus was effectively detected, but it may have emerged in southern china, where little information was available at that time. trained in australia, kennedy shortridge joined the department of microbiology of hong kong university in to provide data on flu viruses to the world health organization. he proposed a hypothesis explaining the role of south china as an 'epicentre' of flu pandemics (shortridge and stuart-harris, ) . flu viruses mutate in waterfowl, particularly ducks, where they develop in the digestive tract without killing the animals. they are transmitted to domestic poultry and pigs, which serve as 'mixing vessels' between birds and humans. influenza is a zoonosis: a disease transmitted from animals with unpredictable effects on humans because of their lack of immunity. south china has a high concentration of waterfowl, poultry, pigs and humans, which speeds up the rate of mutations of flu viruses: it is an "avian influenza virus melting pot" (p. s). serving as a hub between east and west, hong kong is the place from where these new viruses are transmitted to the rest of the world. hence, shortridge's idea is that it should be possible to map flu viruses in their 'animal reservoir' to detect in advance those which will 'jump the species barriers' between birds, pigs and humans. but this raises a new question: how, among all the flu viruses that can be found in animals, to bet on the right 'candidate virus' that will actually cross the species barrier? if this question sounds 'speculative', notice that the only gambling activity allowed in hong kong is horse racing. this is where history comes back in. in , a new flu virus emerged, killing persons out of the it infected. it also killed chickens in poultry farms, and it was estimated that per cent of chickens in the markets had been infected. what was surprising about this virus was its high lethality and the fact that it had jumped directly from birds to humans since it was not found in pigs. this changed the scenario: it was not possible to make a vaccine for this new virus because it killed the chicken embryos used for conventional vaccines ("recombinant and genetically engineered vaccines are being explored", shortridge et al added). but it became possible to imagine a world where this new lethal virus would become pandemic and kill more humans than the 'spanish flu'. it could spread either through humans (although its inter-human transmission had not been proved), through migratory birds (but can sick birds fly?) or through the poultry industry (a factor emphasised by the article). flu viruses are classified by their haemagglutinin (h) and neuraminidase (n) proteins, that allow them to enter and exit from cells. this new virus, called h n , was thus considered as the first candidate for a new pandemic. circulating in birds, h n and h n followed suit. ordering viruses by the range of their pandemicity was not based on probability of genetic mutation but on their actual capacity to jump the species barrier with catastrophic consequences. "it might be possible, for the first time, to have influenza pandemic preparedness at the baseline avian level", wrote shortridge et al ( , p. ): this idea is repeated several times in the article. it means that microbiologists can detect mutations at the species barrier and send out 'early warnings' on those that may become pandemic. the image of a fire is evoked when the authors describe the emergence of h n as "smouldering": if pandemic viruses are detected early enough, they will be like a fire without a flame. this had powerful political consequences. in , in the context of the handover of the british colony to the people's republic, the claim that birds coming from china could start a pandemic from hong kong stirred up tensions. shortridge et al noted: "the incident was the first issue the fledging special administrative region (sar) had to deal with since hong kong's reunification with china. in a sense, the sar felt vulnerable, acutely aware of its international responsibility and that it was being tested" (p. s). in this context, preparing for the pandemic took a military turn, characteristic of 'biosecurity interventions' (lakoff and collier, ) . on december , all the live poultry on the territoryaround . millionwere killed to eradicate the h n virus from its animal reservoir (the term 'incident' may here appear as a euphemism). commenting on 'the controversial slaughter policy', the authors argue that "it is reasonable to believe that this intervention prevented an incipient pandemic progressing to an actual pandemic and thus a pandemic was averted" (p. s). the article thus mixes different registers of anticipatory knowledge: prevention, precaution and preparedness. shortridge et al attributed the idea that a pathogen is detected before it causes a disease to ancient epidemiological principles of prevention in chinese medicine. but the event was analysed as a failure of prevention: it "gave rise to a precautionary principle, essentially a watching brief of preparedness". in the absence of certainty on the h n virus, it was necessary to eradicate it in its animal reservoir "as a preemptive measure" (p. s). if the pandemic had been averted and not prevented, it was certainly imminent: "each year brings us closer to the next pandemic" (p. s). the failure of prevention (building a vaccine for viruses before they become lethal) forced the hong kong government to use precautionary measures, that is, to kill all live poultry, and to strengthen its preparedness by closely monitoring virus mutations in animals. the question for shortridge et al was how hong kong could act as a 'sentinel post'a vocabulary derived from the militarynot only by gathering information on flu viruses on both sides of the human/animal divide, but also by intervening in a situation of uncertainty. if the public and the media, they argued, "could not cope with the uncertainty" (of viral mutations), they would understand public health measures by their impact on food. hence the stress on live poultry markets as a traditional practice that had a major impact on the risk of flu transmission, even if the virus was killed in the process of cooking. the spectre of a coming pandemic became credible to the public when related to the uncertainties of contact with live poultry. this relation between public health and food safety is one of the main drivers for building 'sentinel posts' for avian influenza. if a sentinel post is sensitive to emerging events at the human/animal interface, it can also overreact when betting on the wrong virus (keck and lakoff, ) . it is remarkable that the discussed article was published in just after the outbreak of severe acute respiratory syndrome (sars) in hong kong. the two coauthors of shortridge discovered the human coronavirus responsible for sars (peiris) and its animal origins in south china (guan). but the team initially lost two weeks as it tested for h n , which gives rise to the same symptoms as sars. sars strengthened the position of hong kong as a 'sentinel post' sensitive to diseases emerging from animals and spreading to the rest of the world, but it also showed its vulnerabilities: a biosecurity intervention is a bet on the human/animal interface and its potential outcomes. the article thus concludes: "given the genetic unpredictability of the influenza a viruses, there probably will be many influenza battles to be fought, some to lose some hopefully to win, in the foreseeable future" (p. s). the 'lessons from hong kong' were that the genetic knowledge accumulated on emerging viruses were not enough to face the uncertainties of epidemic outbreaks: hence the need of new relations between humans and animals as 'sentinel devices' where these uncertainties could be converted into early warning signals.t as an anthropologist of science, nature and culture bookend my reading and my thinking, from lévi-strauss to ortner and strathern, from haraway's naturecultures to latour's nature-culture hybrids, from nature/culture as a foundational dichotomy in human thought to the destabilizing of universal binaries, and from stable categories to complexity, gray areas and blurred boundaries. nature/culture has been one of the most provocative conceptual pairings in the social sciences, and sts has challenged the idea of nature versus nurture from the outset. my research focuses on twin studiessometimes described as the 'gold standard' for distinguishing between genetic and environmental influences on health and behaviorso questions about nature and nurture are ever-present, both in my informants' work and my own. scholarship in sts and anthropology challenged me to think about the ongoing work that goes into separating nature from nurture, but reading the work of francis galton, the infamous 'father of eugenics', is what helped me understand the enduring role of twins in the construction of a porous boundary between nature and nurture. galton's research took him in many strange directions, and he made contributions in areas as varied as statistics, fingerprints and family resemblance. he was the first researcher to propose studying twins to differentiate between the effects of 'nature and nurture', a phrase he coined in his influential article "the history of twins, as a criterion of the relative powers of nature and nurture", first printed in fraser's magazine in . he is still cited today by scientists using twins to study the effects of genes and environments, and i first came across his work through tracing alison cool is a mellon sawyer postdoctoral fellow in the department of anthropology at new york university. her research is based in sweden and focuses on collaborations between life scientists and economists who are using twin studies to investigate genetic influences on economic behavior. leçons politiques de l'épidémie de sida security, disease, commerce: ideologies of postcolonial global health an influenza epicentre? the history of twins, as a criterion of the relative powers of nature and nurture. fraser's magazine quoted from the reprint in key: cord- -vw cno p authors: du, yaxing; mak, cheuk ming title: improving pedestrian level low wind velocity environment in high-density cities: a general framework and case study date: - - journal: sustain cities soc doi: . /j.scs. . . sha: doc_id: cord_uid: vw cno p an acceptable pedestrian level wind environment is essential to maintain an enjoyable outdoor space for city residents. low wind velocity environment can lead to uncomfortable outdoor thermal experience in hot and humid summer, and it is unable to remove the pollutants out of city canyons. however, the average wind velocity at pedestrian level is significantly lowered by closely spaced tall buildings in modern megacities. to improve the low wind velocity environment at pedestrian level in high-density cities, a general framework and detailed guidelines are needed. this study is the first time to develop such a framework, and provide detailed guidelines for improving pedestrian level low wind velocity environment in high-density cities. additionally, a detailed review and summarisation of evaluation criteria and improvement measures are presented in this paper, which provide additional options for urban planners. to investigate the performance of the framework, the hong kong polytechnic university campus was utilised as a case study. results showed that pedestrian level wind comfort was greatly improved with the developed framework. the outcomes of this study can assist city planners to improve the low wind velocity environment, and can help policy makers to establish sustainable urban planning policies. outdoor spaces are considered vital constituents of urban environments because they can host entertainment activities that are fundamental to the character of a city and the quality of life of city residents (chen & ng, ) . in particular, outdoor human comfort is extremely important in city planning because it can not only improve the physical and mental health of city residents, but also can help reduce power consumption in residential buildings (amindeldar, heidari, & khalili, ; chatzidimitriou & yannas, ; elnabawi, hamza, & dudek, ; kong et al., ; li, huang, wu, & xu, ) . actually, an enjoyable outdoor thermal comfort can encourage city residents to spend more time in outdoor spaces (chen & ng, ; du, mak, huang, & niu, ) . however, congested airflow at the pedestrian level has become a major concern in the high-density cities because it is the driving force for the transfer of pollutant, heat, and water vapour (ai & mak, ; chatzidimitriou & yannas, ; ignatius, wong, & jusuf, ) . this problem is more serious in densely built cities at low or mid latitudes, such as hong kong and singapore, which suffer from urban heat island and global warming kong et al., ; ng, ; o'malley, piroozfar, farr, & pomponi, ; yang, wong, & jusuf, ). therefore, improving pedestrian level wind environment in high-density cities has become a pressing issue for the establishment of comfortable, healthy, and sustainable cities. a strong relationship between low wind velocity environments at pedestrian level and unfavourable outdoor living environments has been widely identified in high-density cities (ignatius et al., ) . for sub-tropical and densely built cities, such as hong kong, the wind speed and radiant temperature are the most influencing factors of pedestrian thermal comfort in hot and humid summers . in particular, cheng, ng, chan, and givoni ( ) reported that even in shaded environments, the thermal sensation of respondents was not neutral when wind velocity was below . m/s during the hot and humid summer of hong kong. the cooling effect of wind flow can contribute to the reduction of heat stress in urban cities (memon, leung, & liu, ; priyadarsini, hien, & wai david, ; yang & li, ) . it was identified that a wind speed of m/s to . m/s could lower the air temperature by nearly °c (erell, pearlmutter, & williamson, ) . thus, low wind velocity environment has a negative effect on outdoor thermal comfort, particularly in hot and humid summers. in addition, the dispersion and dilution of airborne pollutants in the urban environment depend strongly on wind flow because it can help remove pollutants to external surroundings (ai & mak, a ,b, hang & li, ; kim & baik, ; n'riain, fisher, martin, & https://doi.org/ . /j.scs. . . received may ; received in revised form july ; accepted august littler, ) . the outbreak of severe acute respiratory syndrome (sars) in hong kong urged the officials and city residents to consider the pollutant dispersion in their living environment (li, duan, yu, & wong, ) . by analysing the results from field measurements, jones, fisher, gonzalez-flesca, and sokhi ( ) indicated that traffic pollutants could not be properly dispersed or diluted with weak wind conditions in urban areas. moreover, low wind velocity environments in the street canyons could not form the coupling process to remove the pollutants from the street canyons to the upper atmosphere (jones et al., ; vignati, berkowicz, & hertel, ) . there have been a substantial investigations into the improvement of pedestrian level wind environment in the past few decades (blocken, stathopoulos, & van beeck, ; du, mak, huang et al., , c hang, sandberg, & li, ; kubota, miura, tominaga, & mochida, ; liu, niu, & xia, ; mirzaei & haghighat, ) . tsang, kwok, and hitchcock, ( ) conducted wind tunnel tests to investigate the influence of building dimensions, separations, and podiums on pedestrian level wind environment. their results indicated that wide buildings with podiums should be discouraged in building designs in high-rise cities, for resulting in large areas of low wind velocity environment around buildings. in the study of kubota et al. ( ) , the relationship between the gross building coverage ratio and the wind environment at pedestrian level from actual japanese city was quantitatively studied using wind tunnel tests. the results showed that a small gross coverage ratio should be adopted in city planning because a high gross coverage ratio results in low wind velocity at pedestrian level, especially for the detached houses. niu et al. ( ) conducted field measurements in a university campus in hong kong, and their findings indicated that local wind amplification could be achieved by utilising an innovative building design (lift-up design). numerically studied the wind environment in idealized high-rise urban areas, and reported that building height variation could improve pedestrian level wind environment. apart from the above mentioned measures, the hong kong government has issued the air ventilation assessment (ava) scheme to enhance wind flow movement at pedestrian level (ng, ) . later, new wind comfort criteria were proposed by , which were aimed at assessing wind comfort in low wind velocity environments. however, no general framework that provides detailed application procedure has been presented. therefore, a general framework that can be applied to improve pedestrian level wind environment is in urgent needed. in this study, a general framework for improving low wind velocity environment at pedestrian level was developed, and this paper provides detailed guidelines for the framework. moreover, measures that have been utilised in improving the low wind velocity environment in highdensity cities were thoroughly reviewed. meanwhile, the evaluation criteria aimed at assessing low wind velocity environment at the city scale are summarized in this paper. a case study of the hong kong polytechnic university (hkpolyu) campus model was used to elaborate this framework and demonstrate its performance. the remainder of this paper is structured as follows: section describes the general design framework for improving the low wind velocity environment and describes its detailed guidelines. sections and summarise the evaluation criteria and improvement measures. the performance of the design framework was investigated with a case study of hkpolyu campus, which is presented in section . concluding remarks are given in section . this section describes the design framework and guidelines in detail. note that the present study only concerns the improvement of low wind velocity environments in high-density cities. however, the general framework developed in this study can also be used to mitigate the nuisance caused by strong wind conditions. in doing so, the improvement measures and evaluation criteria need to be re-determined. a flow chart of the design framework for improving the pedestrian level low wind velocity environment in a high-density city is shown in fig. . meanwhile, the basic parameters for the design framework are summarized in fig. . based on figs. and , the detailed guidelines for the improvement of pedestrian level low wind velocity environment are presented as follows: • step : basic information on the target area should be collected before evaluating the wind environment at pedestrian level. this includes the target area, surrounding area, local wind climate, building information, and geomorphological information. it is well known that urban wind flow is very complex and is closely related to the urban morphology, especially in high-density cities. thus, for scaled models, accurate reproduction of the buildings and geomorphological features of the target area are very important. these y. du, c.m. mak sustainable cities and society ( ) - geometric data can be obtained from gis or government departments. moreover, the target area should include surrounding buildings and infrastructure, which have a significant impact on the pedestrian level wind environment in the target area. furthermore, the local wind climate should be acquired from nearby weather stations. • step : based on the obtained basic information, the wind environment at pedestrian level can be obtained by field measurements (jones et al., ; niu et al., ) , wind tunnel tests (du, mak, huang et al., ; kubota et al., ; tsang et al., ) or computational fluid dynamics (cfd) simulations (blocken, janssen, & van hooff, du, mak, liu et al., ; du, mak, & ai, ; tominaga, mochida, murakami, & sawaki, ) . the field measurements should be conducted for a long time due to the uncertainty and unsteadiness of meteorological conditions (schatzmann & leitl, ; schatzmann, rafailidis, & pavageau, ) . moreover, the building models in the wind tunnel tests or cfd simulations should be replicated as close to the real buildings as possible. in addition, the prediction process should rigorously follow the practice guidelines and regulations, such as the awes and asce quality assurance for wind tunnel (asce, ; awes, ) and cost and aij guidelines for cfd simulation (franke, ; tominaga, mochida, yoshie et al., ). step : the low wind velocity area that needs to be improved can be determined by combining the prediction results obtained in step and the evaluation criteria. the main features of the evaluation criteria and parameters for improving low wind velocity environments are summarized in section . step : the low wind velocity environment can be improved by adopting improvement measures such as using the lift-up design to create a void space underneath the building (du, mak, liu et al., ; niu et al., ) or adopting openings in building design to guide wind flow through buildings (fan, chau, chan, & jia, ; yuan & ng, ) . the main findings of previous studies on improving weak wind environment by adopting innovative building designs are detailed reviewed in section . • step : the pedestrian level wind environment should be re-evaluated after adopting improvement measures. if the improved wind environment meets the requirements of the evaluation criteria, the wind environment in the target area is then viewed as an acceptable wind environment. otherwise, new improvement measures should be adopted in the target area as illustrated in fig. . similar to the fact that strong wind conditions can be evaluated by using the existing wind comfort criteria (hunt, poulton, & mumford, ; isyumov & davenport, ; lawson, ; melbourne, ; willemsen & wisse, ) , the low wind velocity environment should be assessed by suitable evaluation criteria. the wind comfort criteria aimed at assessing low wind velocity environments in high-rise cities have been established in past years. this section presents a detailed review and summarisation of the evaluation criteria for low wind velocity environments, as well as the evaluation parameters for outdoor wind environments. in order to enhance pedestrian level wind ventilation, the hong kong government has stipulated elaborate technical guidelines and protocols, titled "feasibility study for establishment of air ventilation assessment (ava) system" (ng, ). this ava scheme was established specifically for low wind conditions in the high-density urban area. the main purpose of the ava scheme is to improve wind flow movement at pedestrian level and to assess the influence of newly built developments on the neighbouring wind environment. the principle of the ava scheme is "the more, the better"; and thus only a low wind threshold value was established in this scheme (ng, ). this means that the pedestrian level wind environment is acceptable when the wind velocity is over . m/s for % of the time. it can be seen that the ava scheme aiming for enhancing pedestrian level wind environment has no specific regulations on wind comfort. unlike the wind comfort criteria adopted from overseas, which mainly focuses on strong wind conditions (hunt et al., ; isyumov & davenport, ; lawson, ; melbourne, ; willemsen & wisse, ) , the new wind comfort criteria proposed in our earlier study are intended specifically for low wind velocity environments . additionally, the new wind comfort criteria are established seasonally in consideration of the subtropical weather conditions in hong kong. a low wind threshold parameter from ava scheme was adopted for hot season criteria. moreover, the parameters in the new wind comfort criteria were chosen by thoroughly reviewing the existing wind comfort criteria to adapt to low wind conditions. similar to the indicators in the ava, the mean wind velocity ratio (mvr) and overall mean wind velocity ratio (omvr) were utilised as indicators in the new wind comfort criteria. these two indicators are defined as follows: here, i is the approaching wind direction; mv pi is the mean wind velocity at any area of pedestrian level when the approaching wind direction is i ; mv r is the mean wind velocity at a reference height ( m in the prototype) when the approaching wind comes from i direction; and p i is the occurrence probability of approaching wind coming from i direction. as mentioned earlier, the omvr is used directly instead of using actual wind velocity because of its convenience for scaled models, namely cfd simulation which can provide sufficient spatial data or wind tunnel measurement when sufficient measurement points are used. note that the application of wind comfort assessment can also be achieved by on-site measurement on the condition that the monitored points are sufficient enough and the wind data has been monitored for a long time, i.e. several months or years. details of the new wind comfort criteria are listed in table . apart from the above two criteria that focus on low wind environment at pedestrian level, different parameters for evaluating the outdoor wind environment in urban areas have also been proposed and utilised in current researches. some of them were adopted from indoor ventilation research. detailed descriptions of the commonly used assessment parameters and their corresponding studies are summarized in table . in view of the congested airflow in high-rise cities, many innovative building designs (passive and active) have been intensively investigated in the past few years. since the geometric characteristics of buildings can modify airflow patterns at pedestrian level, specific building designs should be deployed to improve pedestrian level wind environment. this section provides a detailed review of the improvement measures in current studies, which also provides additional options for city planners to improve the low wind velocity environment at pedestrian level. the lift-up design, in which the main building structure is elevated off the ground by pillars or a combination of columns and shear walls, is a potential solution for improving the low wind velocity environment at pedestrian level. a schematic diagram and a photo of the lift-up design in a university campus are shown in fig. . the void place underneath the elevated building is known as the lift-up area. the main purpose of the lift-up area is to minimize the wind flow obstruction at pedestrian level and to function as a corridor for the wind flow. thus, the wind environment at pedestrian level is improved significantly. moreover, the lift-up area can be utilised as a passageway for pedestrians, recreational zone, and parking zone. several studies have investigated the effect of the lift-up design on improving low wind velocity environment in high-density cities. they reported a clear correlation between wind speed enhancement and the implementation of lift-up design, and suggested that it was necessary to adopt lift-up design in urban planning and architectural design. a field table new wind comfort criteria for hong kong . wind comfort criteria for cold seasons category threshold velocity exceedance probability activity description category threshold velocity exceedance probability activity description flow rate (q) calculated as the ratio between the flow entering the target area and the "free" flow rate far upstream of the same area in windward opening. a small q value means that the domain has a low ventilation rate. generic/ d/circular block with or sectors (skote, sandberg, westerberg, claesson, & johansson, ) generic/ d/parallel buildings (blocken, carmeliet, & stathopoulos, ) generic/ d/round shaped, square, rectangular city model (hang, li, sandberg, & claesson, , a generic/ d/courtyard (moonen, dorer, & carmeliet, ) purging flow rate (pfr) the net flow rate needed to remove pollutants. a small pfr value means that the domain has limited airflow movement. generic/ d/two-building model and building arrays (bady, kato, & huang, ) generic/ d/high-rise square arrays generic/ d/aligned arrays, semiopen street roof (hang et al., ) generic/ d/aligned and staggered building arrays (lin, hang, li, luo, & sandberg, ) generic/ d/street void model (bu, kato, ishida, & huang, ) air change rate (ach) the value of air change in volume per hour for the domain. a small ach value means that the domain has limited airflow movement. generic/ d/street canyon (li, liu, & leung, ) generic/ d/street canyon generic/ d/long street canyon (hang et al., ) generic/ d/aligned arrays of cubes (hang & li, a,b) local mean age of air (τp) the time required for a portion of the airflow to get to a specified point after entering the domain. a small τ p value means that the domain is poorly ventilated. generic/ d/round, square, long rectangular city model (hang et al., a) generic/ d/long street canyon ) generic/ d/aligned arrays, semiopen street roof (hang et al., ) generic/ d/building array of cubes (buccolieri et al., ) y. du, c.m. mak sustainable cities and society ( ) - measurement study in the hkpolyu campus found that wind speed was amplified by the lift-up design in a local precinct . xia, liu, niu, and kwok, ( ) assessed the influence of the lift-up design on the pedestrian level wind environment using wind tunnel measurement, and found that integrating the lift-up design in existing building configurations can enhance the wind speed around buildings. in a study of du, mak, liu et al. ( ) , the effects of the lift-up design on pedestrian level wind environment in different building configurations, namely the slab shaped building, the corner shaped building, the semi-open shaped building and the close shaped buildings, were quantitatively evaluated using cfd simulation. the results showed that the lift-up design could effectively improve the low wind velocity environment and its enhancement highly relied on the approaching wind direction. tse et al. ( ) found that the lift-up core dimensions govern the pedestrian level wind speed around an isolated building using wind tunnel measurement, and suggested that proper core dimensions should be selected before implementing the lift-up design in architectural design. similarly, du, mak, and li ( ) proposed a multi-variable optimization method to determine the appropriate liftup dimensions for an optimum wind environment at pedestrian level using cfd simulation. liu et al. ( liu et al. ( , studied the pedestrian level wind environment around isolated buildings with and without the lift-up design using cfd simulation, and found that the lift-up design could improve the wind speed around isolated buildings, but the effects were only limited to the neighbouring area. the above mentioned studies confirm that the lift-up design is a promising solution for low wind velocity environments in densely built urban areas, especially at pedestrian level. the arcade design, known as "semi-open spaces", in which an outcorridor is formed from a line of arches on the side of a main building, as shown in fig. . it is frequently utilised as a pathway for pedestrians because it can provide shelter from direct solar radiation and rain. a number of studies have been conducted about the effect of the arcade design on improving the low wind velocity environment in densely built-up areas. the cfd simulation study conducted by hang, luo, sandberg, and gong ( ) showed a direct relationship between the arcade roof designs and the natural ventilation characteristics in two ideal urban models with different wind directions. wen, juan, and yang ( ) studied the effectiveness of the arcade design on the improvement of flow aeration in ideal urban canyons using cfd simulation, and concluded that the arcade design had the ability to improve low wind velocity environments at a city scale. juan, yang, wen, lee, and wang ( ) optimized the wind environment in real urban streets by manipulating the configurations of the arcade design in cfd simulation. the results indicated that a wider arcade provided a better wind environment around buildings in a high-density city, which corresponds with the results obtained by du, mak, li et al. ( ) . it can be concluded from the above studies that the arcade design has the potential to improve the low wind velocity environment in high-rise urban cities with proper arrangement. the building opening design is a solution that enhances wind speed by increasing the permeability of buildings. fig. shows a schematic diagram of a building opening and a photo of the opening design utilised in a real building. based on the cfd simulation results, yuan and ng ( ) concluded that building openings could enhance wind speed in compact urban canyons without losing land use efficiency. their study also suggested that a higher pedestrian level wind velocity could be achieved when the opening was closer to the ground level and when the size of the opening was larger. in a study conducted by fan et al. ( ) , different types of building openings inside canyons were investigated using cfd simulation. the study concluded that building openings could effectively improve the low wind velocity environment, and considering the values in the development floor area, an opening value of % was enough to improve the low wind velocity environment. moreover, the cfd simulation studies by hang and li ( a) , hang and li ( ) indicated that the airflow ventilation rate could be improved significantly when buildings in a compact array were openbased (have openings underneath the building). thus, the building opening design presents prominent advantage in improving the low wind velocity environments in compact high-rise cities. aside from the specific architectural designs that can be integrated into building configurations, building disposition has been proven to improve pedestrian level wind environment around compact and tall buildings. to improve the low wind velocity environment, strategies including low building area density ( , buccolieri, sandberg, & di sabatino, ; hang & li, a) , low building aspect ratio ho, liu, & wong, ; liu, leung, & barth, ) , non-uniform building height (gu, zhang, cheng, & lee, ; hang & li, a; nelson, pardyjak, klewicki, pol, & brown, ) , street orientation (hang, sandberg, & li, , b, ramponi, blocken, de coo, & janssen, and aligned arrays (coceal, thomas, castro, & belcher, ; hanna, tehranian, carissimo, macdonald, & lohner, ) have been used in precinct planning. the key findings of the building arrangements and their contribution towards improving low wind velocity environments are summarized in table . it is noteworthy that the above mentioned measures are passive strategies to improve low wind velocity environments in high-density cities. in studies conducted by mirzaei and haghighat ( ) , mirzaei and haghighat ( ) , an active pedestrian level ventilation system was proposed. the basic idea of this system was that it induced airflows from the roof of the building through ventilation ducts to pedestrian level in the street canyon. the performance of the ventilation system under different atmospheric conditions was numerically studied using cfd simulations of stable, neutral, and unstable conditions. additionally, different ventilation strategies had been proposed for the ventilation system. their investigation results indicated the application feasibility of the pedestrian level ventilation system. more detailed information on this active pedestrian ventilation system can be found in the studies of mirzaei and haghighat ( ) ; mirzaei and haghighat ( ) . from the above the above literature review, the effectiveness of different improvement measures can be summarized as follows: (i) the building dispersion can improve wind environment in the whole city, and the pedestrian level wind environment can be affected subsequently. however, this improvement measure may lead to low land use efficiency and it is impractical for the existing urban areas. (ii) the arcade design and the lift-up design can enhance wind ventilation at pedestrian level directly without sacrificing any land use, but the result of the arcade design is less effective than the lift-up design. (iii) the position and size of the building opening can affect the effectiveness of the improvement. (iv) the active strategy of the pedestrian level ventilation system is more controllable than the above passive building design, but it requires energy consumption. thus, the passive strategy should be preferred over active strategy for the sustainability of city development. the hkpolyu campus was selected as the study area in this study. the campus is located in the downtown area of hong kong, which is closely surrounded by tall and dense buildings. despite the meteorological advantage of being adjacent to the victoria harbour, the pedestrian level wind environment in the campus is low due to the compact neighbouring buildings. to accurately reproduce the wind environment in the campus, surrounding buildings that were up to km from the campus were also included in the model. the campus building information was obtained from architectural drawings, and the geographical data of surrounding buildings were acquired from government department. to obtain the pedestrian level wind environment in the campus, the wind tunnel test approach was utilised in this study. the clp power wind/wave tunnel facility (wwtf) at the hong kong university of science and technology (hkust) were used to conduct the wind tunnel tests. the scaled ratio for the campus model with its surroundings was : , and the campus model was reproduced in great detail (see fig. (a) ). wind directions were measured during the wind tunnel tests at an interval of . °from °(north) to °. a reference sensor was located at m high ( m in full-scale) above the edge of the turn table on the windward side. the approaching wind profiles were acquired by grouping and fitting from previous topographic study, which could represent local wind conditions in real life. the measured and target values of the wind profiles and their corresponding approaching wind directions are presented in fig. (b) , where the mean wind velocity at the reference height ( m in prototype) was around m/s. the measured errors were within %, which confirmed the confidence in the measurement data. the similarity requirements were strictly examined during the wind tunnel tests, and the blockage ratio was . % with reynolds numbers (re) over × . these met the requirements of the quality wind tunnel test standards asce ( ) and awes ( ) manuals). the kanomax velocity sensors were utilised for the measurements of pedestrian level wind environment, and they were y. du, c.m. mak sustainable cities and society ( ) - evenly distributed in the campus model. moreover, the kanomax velocity sensors were carefully calibrated before the wind tunnel measurements. as indicated in section . , the new wind comfort criteria proposed by were developed specifically for low wind velocity environment. in particular, the parameters in the new wind comfort criteria were chosen explicitly to adapt to the low wind velocity environment in hong kong. moreover, the new wind comfort criteria were established seasonally in consideration of the subtropical weather conditions in hong kong. thus, the proposed new wind comfort criteria are adopted as the evaluation criteria in this case study. a detailed description of the new wind comfort criteria is presented in section . . with respect to the fact that the hot and humid summer is the critical season in hong kong, only the wind comfort for summer is considered in this study. it should be mentioned that the mean wind velocity at m (reference height) in hong kong is m/s in the summer season (planning department of the hksar, ). the wind comfort levels and their corresponding threshold values for the hkpolyu campus are presented in table . the local wind climate for the hkpolyu campus was acquired by calibrating hourly wind data from to from a nearby weather station, namely the king's park meteorological station of the hong kong observatory. detailed information on the meteorological station can be found in the website (observatory, december ). the wind rose in summer for hkpolyu campus is presented in observatory ( ) fig. . studies on the building arrangements and improvements of low wind velocity environments. model configuration results reference low building area density generic/ d/ aligned square building arrays the city model with lower building area density had faster wind flow movement inside street canyons than that with higher building area density. (hang & li, ) generic/ d/ aligned square building arrays lower building density provides a better wind environment in both main streets and secondary streets, especially in downstream regions. (hang & li, a) generic/ d/ cubical buildings arrays the wind environment inside the city model worsened with increasing packing density, and the model with low packing density had a good wind environment. (buccolieri et al., ) low building aspect ratio generic/ d/ long street model the larger the value of the street aspect ratio was, the weaker of the wind environment inside the street model was when the approaching wind was parallel to the street model. generic/ d/ street canyon model a smaller street aspect ratio presented lower aerodynamic resistance to the approaching wind, and thus the wind environment was better than that of the model with a larger street aspect ratio. (ho et al., ) generic/ d/ street canyon model a smaller street aspect ratio had better air ventilation performance and a greater pollutant removal rate than that of the model with a larger street aspect ratio. non-uniform building height generic/ d/ square building array larger standard deviations in building height variability could lead to better pedestrian level ventilation. generic/ d/ aligned square building array building height variation improved the low wind velocity environment in secondary streets. (hang & li, a) generic/ d/ street canyon large-scale wind flow change was found in non-uniform street canyons, which in turn improved the wind environment inside street canyons. (gu et al., ) actual street canyon/ d/ actual street canyon field measurements in an actual street canyon indicated that heterogeneous building heights could enhance wind speed by means of horizontal transport and enhanced turbulence. (nelson et al., ) street orientation generic/ d/ round-shaped model for the round-shaped city model, an oblique approaching wind to the main street produced a better wind environment than that with a parallel approaching wind direction. (hang et al., a, b) generic/ d/ generic urban model the wind environment was better with oblique and perpendicular approaching wind directions to the main street than that with a parallel approaching wind direction. (ramponi et al., ) aligned array generic/ d/ cubical obstacle staggered square building arrays had a stronger form drag than aligned arrays. (coceal et al., ) generic/ d/ simple obstacle array higher wind speed was found in between the building obstacles in aligned arrays compared to that in staggered arrays. (hanna et al., ) y. du, c.m. mak sustainable cities and society ( ) - to facilitate the illustration of the developed framework, the lift-up areas in the campus model were firstly blocked during the wind tunnel tests, as shown in fig. . this means that there was no lift-up design in the campus model for this case (preliminary case). the evaluation results of wind comfort in summer for the preliminary case are presented in fig. . it can be seen that in the central part of the campus, the areas around building y and the area between core a and core b had higher omvr values than the other parts of the campus. thus, these areas had acceptable wind comfort. besides, the majority of the campus had low omvr values, which lead to unfavourable wind comfort. furthermore, nearly % of the spaces in the campus were unfavourable for any pedestrian activity. in general, the wind comfort in the campus was not suitable for pedestrian activities in hot and humid summers. taking the sustainability of the city development into consideration, the passive building designs are used in this case study. as concluded in section . , the arcade design and the lift-up design can both improve the pedestrian level wind environment directly, but the lift-up design is more effective than the arcade design. thus, the lift-up design is adopted as the improvement measure in this case study. buildings that adopted the lift-up design are indicated on the campus map by blue dashed lines in fig. . fig. presents the wind comfort evaluation results after adopting the lift-up design in the campus. as shown in fig. , the central parts of the campus had higher wind speeds than other parts of the campus, and most of the lift-up area had acceptable wind comfort. for the podium area in the campus, the area of acceptable wind comfort was larger than that in the preliminary case. overall, less than % of the spaces in the campus were unfavourable for pedestrian activities. compared to the preliminary case, the wind comfort in the campus was greatly improved after adopting the lift-up design. however, large areas in the campus still had unfavourable wind comfort. the opening design is also effective in improving pedestrian level wind environment. as summarized in section . , the location and size of the building opening are important in improving pedestrian level wind environment. thus, the opening design is adopted in building y because the building y is the highest and slab-shaped building in the campus. since the building y is on the edge of the campus, the opening design is located in the centre of the building y. fig. shows the photo of the opening design in building y during wind tunnel tests. note that the dimensions in fig. are in prototype. fig. shows wind comfort evaluation results after adopting the lift-up design and the building opening in the campus model. compared to fig. , the wind comfort of the areas between building m and building y had significantly improvement after adopting the opening design in building y. besides, more than % of the places in the campus had acceptable wind comfort, which suggested satisfactory wind comfort for pedestrian activities. thus, the wind comfort in the campus for summer was significantly improved after adopting lift-up design and opening design. considering that the majority areas in the campus had acceptable wind comfort, the wind comfort in the campus could be viewed as acceptable in general. to quantitatively assess wind comfort by adopting the above mentioned improvement measures, this section presents the results of omvr in three cases. the results of omvr in three cases are given in fig. . it can be seen that when the campus had no improvement measures (preliminary case), nearly % of omvr values were below . , which meant that nearly % of the areas in the campus had unfavourable wind comfort. after adopting lift-up design in the campus, the values of omvr had been greatly improved. however, half of the omvr values were still below . . nevertheless, by adding opening in y building, the values of omvr were further improved and more than half of the omvr values were over . . this suggested that more than half of the areas in the campus had acceptable wind comfort. to stress the importance of improving low wind velocity environments in high-density cities, the influences of low wind velocity environments on pollutant dispersion, thermal comfort, and wind comfort were presented in this paper. a general design framework was developed, and detailed guidelines on improving the pedestrian level low wind velocity environment in high-density cities were offered. the general design framework was presented in the form of a flowchart, which was systematic and effective. evaluation criteria that aim to improve the low wind velocity environment were also reviewed in detail, namely the ava scheme, the new wind comfort criteria for hong kong, and city ventilation parameters. moreover, the strategies used to improve low wind velocity environments were reviewed in detail, including the lift-up design, the arcade design, the building opening, building disposition, and the active pedestrian ventilation system. a case study of an existing university campus was used to investigate the performance of the proposed design framework. wind tunnel tests were conducted to obtain the pedestrian level wind environment in the campus model. the choice of the evaluation criteria were chosen based on the review results presented in section , and the new wind comfort criteria were selected. the wind comfort of the campus model was improved by vigorously following the proposed design framework, and the improvement measures were chosen based on the review results presented in section . specifically, three distinctive cases were examined, namely the campus model without the lift-up design, the campus model with the lift-up design, and the campus model with an opening in building y. results showed that the proposed design framework could help in improve the low wind velocity environment at pedestrian level. this study mainly focused on improving congested wind flow caused by tall and dense building arrays. the design framework and guidelines described in this paper were established under the presumption that low wind velocity environments have resulted in serious issues for urban residents. however, this design framework can also be applied to other wind environments, such as strong wind conditions in sparsely populated cities. this can be achieved by replacing the improvement measures and evaluation criteria with the current measures and criteria. moreover, this study indicated that favourable wind environments in local precincts could be achieved by integrating innovative building designs. the low wind velocity environment can be improved by following the proposed design framework, which also corresponds with government policies of enhancing ventilation in high-rise cities. in particular, the evaluation criteria and the improvement measures reviewed in this study can be used in practical developments. for example, the lift-up design could be used to improve the pedestrian level wind environment for an existing urban area. these findings can help urban planners and policy makers improve low wind velocity environments at pedestrian level, and build a sustainable city. large eddy simulation of wind-induced interunit dispersion around multistory buildings from street canyon microclimate to indoor environmental quality in naturally ventilated urban buildings: issues and possibilities for improvement determination of single-sided ventilation rates in multistory buildings: evaluation of methods modeling of coupled urban wind flow and indoor air flow on a high-density near-wall mesh: sensitivity analyses and case study for single-sided ventilation the effect of personal and microclimatic variables on outdoor thermal comfort: a field study in tehran in cold season american society of civil engineers (asce) manuals and reports on engineering practice no assurance manual for wind-engineering studies of buildings (awes-qam- ) towards the application of indoor ventilation efficiency indices to evaluate the air quality of urban areas cfd evaluation of wind speed conditions in passages between parallel buildings-effect of wall-function roughness modifications for the atmospheric boundary layer flow cfd simulation for pedestrian wind comfort and wind safety in urban areas: general decision framework and case study for the eindhoven university campus. environmental modelling & software pedestrian-level wind conditions around buildings: review of wind-tunnel and cfd techniques and their accuracy for wind comfort assessment new criteria for assessing local wind environment at pedestrian level based on exceedance probability analysis city breathability and its link to pollutant concentration distribution within urban-like geometries microclimate design for open spaces: ranking urban design effects on pedestrian thermal comfort in summer street canyon design and improvement potential for urban open spaces; the influence of canyon aspect ratio and orientation on microclimate and outdoor comfort outdoor thermal comfort and outdoor activities: a review of research in the past decade outdoor thermal comfort study in a subtropical climate: a longitudinal study based in hong kong mean flow and turbulence statistics over groups of urban-like cubical obstacles modelling of pedestrian level wind environment on a high-quality mesh: a case study for the hkpolyu campus towards an integrated method to assess effects of lift-up design on outdoor thermal comfort in hong kong new criteria for assessing low wind environment at pedestrian level in hong kong application of a multi-variable optimization method to determine lift-up design for optimum wind comfort effects of lift-up design on pedestrian level wind comfort in different building configurations under three wind directions thermal perception of outdoor urban spaces in the hot arid region of cairo urban microclimate: designing the spaces between buildings a decision support tool for evaluating the air quality and wind comfort induced by different opening configurations for buildings in canyons best practice guideline for the cfd simulation of flows in the urban environment effect of uneven building layout on air flow and pollutant dispersion in non-uniform street canyons age of air and air exchange efficiency in high-rise urban areas and its link to pollutant dilution ventilation strategy and air change rates in idealized high-rise compact urban areas wind conditions in idealized building clusters: macroscopic simulations using a porous turbulence model wind conditions and ventilation in high-rise long street models natural ventilation assessment in typical open and semi-open urban environments under various wind directions age of air and air exchange efficiency in idealized city models effect of urban morphology on wind condition in idealized city models on the contribution of mean flow and turbulence to city breathability: the case of long streets with tall buildings the influence of building height variability on pollutant dispersion and pedestrian ventilation in idealized high-rise urban areas comparisons of model simulations with observations of mean flow and turbulence within simple obstacle arrays preliminary study of the parameterisation of street-level ventilation in idealised two-dimensional simulations the effects of wind on people; new criteria based on wind tunnel experiments urban microclimate analysis with consideration of local ambient temperature, external heat gain, urban ventilation, and outdoor thermal comfort in the tropics the ground level wind environment in built-up areas the use of measurement programmes and models to assess concentrations next to major roads in urban areas optimization procedures for enhancement of city breathability using arcade design in a realistic high-rise urban area a numerical study of the effects of ambient wind direction on flow and dispersion in urban street canyons using the rng k-ε turbulence model regulation of outdoor thermal comfort by trees in hong kong wind tunnel tests on the relationship between building density and pedestrian-level wind velocity development of guidelines for realizing acceptable wind environment in residential neighborhoods the widn content of the built environment feasibility study of a pcm storage tank integrated heating system for outdoor swimming pools during the winter season multi-zone modeling of probable sars virus transmission by airflow between flats in block e development of a model for the determination of air exchange rates for street canyons quantitative ventilation assessments of idealized urban canopy layers with various urban layouts and the same building packing density on the prediction of air and pollutant exchange rates in street canyons of different aspect ratios using large-eddy simulation combining measured thermal parameters and simulated wind velocity to predict outdoor thermal comfort criteria for environmental wind conditions effects of building aspect ratio and wind speed on air temperatures in urban-like street canyons a novel approach to enhance outdoor air quality: pedestrian ventilation system pollution removal effectiveness of the pedestrian ventilation system evaluation of the ventilation potential of courtyards and urban street canyons using rans and les flow field and pollution dispersion in a central london street properties of the wind field within the oklahoma city park avenue street canyon. part i: mean flow and turbulence statistics policies and technical guidelines for urban planning of high-density cities -air ventilation assessment (ava) of hong kong a new method to assess spatial variations of outdoor thermal comfort: onsite monitoring results and implications for precinct planning urban heat island (uhi) mitigating strategies: a case-based comparative analysis observatory king's park meteorological station microclimatic modeling of the urban thermal environment of singapore to mitigate urban heat island cfd simulation of outdoor ventilation of generic urban configurations with different urban densities and equal and unequal street widths issues with validation of urban flow and dispersion cfd models some remarks on the validation of small-scale dispersion models with field and laboratory data numerical and experimental studies of wind environment in an urban morphology comparison of various revised k-ε models and les applied to flow around a high-rise building model with : : shape placed within the surface boundary layer aij guidelines for practical applications of cfd to pedestrian wind environment around buildings wind tunnel study of pedestrian level wind environment around tall buildings: effects of building dimensions, separation and podium adopting 'lift-up' building design to improve the surrounding pedestrianlevel wind environment comparison of air quality in streets of copenhagen and milan, in view of the climatological conditions enhancement of city breathability with half open spaces in ideal urban street canyons design for wind comfort in the netherlands: procedures, criteria and open research issues effects of building lift-up design on the wind environment for pedestrians thermal conditions and ventilation in an ideal city model of hong kong thermal comfort in outdoor urban spaces in singapore building porosity for better urban ventilation in high-density cities -a computational parametric study the work described in this paper was fully supported by a grant from the research grants council of the hong kong special administrative region, china (project no. c - g). key: cord- -bwsw nlr authors: yeung, k.l.; yeung, gladys w.y.; chan, miranda w.s.; lee, sara b.c.; choi, kenny t.y.; lee, larry l.y.; tang, simon y.h.; graham, colin a.; chan, jimmy t.s. title: knowledge of inter-facility transport among emergency nurses in hong kong: a questionnaire survey date: - - journal: int emerg nurs doi: . /j.ienj. . . sha: doc_id: cord_uid: bwsw nlr introduction: inter-facility transport (ift) is a dynamic process and its quality largely depends on pre-transport preparation, emergency equipment support and recognition of possible en route adverse events. this study aims to evaluate knowledge of ift among emergency nurses of three accident and emergency departments in hong kong. methods: questionnaires were distributed to registered nurses of the three departments. data was sought on participants’ characteristics, knowledge on equipment preparation and management of en route adverse events. four clinical ift scenarios were set for participants and answers were scored. measured outcomes were defined as ( ) relationships between clinical experience and relevant training in ift with questionnaire results, ( ) staff knowledge of the equipment carried routinely in ambulances and ( ) the en route adverse events encountered according to the participants’ past experience. results: participants’ test scores ranged from to (out of ) with a mean of . ( % confidence interval . – . ). participants with more clinical experience demonstrated significantly better test scores (p < . ). most participants were familiar with the monitoring devices carried in ambulances but were less familiar with the pharmacologic agents and airway devices available routinely in hong kong ambulances. thirty participants ( %) had encountered en route adverse events in the past. conclusion: nurses in emergency departments in hong kong have good knowledge of ift. extensive clinical experience is related to better ift knowledge. ift training for nurses should emphasize available ambulance service resources and capabilities. ift with questionnaire results, ( ) staff knowledge of the equipment carried routinely in ambulances and ( ) the en route adverse events encountered according to the participants' past experience. results: participants' test scores ranged from to (out of ) with a mean of . ( % confidence interval . - . ). participants with more clinical experience demonstrated significantly better test scores (p < . ). most participants were familiar with the monitoring devices carried in ambulances but were less familiar with the pharmacologic agents and airway devices available routinely in hong kong ambulances. thirty participants ( %) had encountered en route adverse events in the past. conclusion: nurses in emergency departments in hong kong have good knowledge of ift. extensive clinical experience is related to better ift knowledge. ift training for nurses should emphasize available ambulance service resources and capabilities. c elsevier ltd. all rights reserved. the role of inter-facility patient transport (ift) is constantly being extended and expanded especially in smaller scale local hospitals in hong kong. this trend can be explained by three reasons. firstly, there is ongoing centralization of specialist services to tertiary centers and this reorganization of services increases demand for ift. secondly, the difficult first hand experience of the severe acute respiratory syndrome (sars) crisis sensitized all healthcare staff to the importance of maintaining strict infection control measures. strict infection control policies have led to declines in both patient turnover and the capacities of the wards. this clinical framework further aggravated existing bed constraints and a high quality ift service became a must. in addition, ift also plays a role in supplementing the primary trauma diversion program as trauma patients who have airway or breathing compromise that cannot be overcome at the scene or in transit require stabilization in the nearest hospital (cheung et al., ) . ift is a dynamic process which should occur when the benefits to the patient exceed the risks of transport. the decision for transport is inherently risky and it means that accompanying personnel have a responsibility to handle any complications in transit on their own (lee et al., ; warren et al., ) . in hong kong, ambulances are the main choice of transport medium, with only exceptional cases being transported by helicopter or police launch when handling cases from outlying islands or rural hiking spots during adverse weather when air transport not possible (college organizing committee of intensive care, ) . it is unknown what the general level of ift knowledge among registered nurses in hong kong is at present. nurses from the accident and emergency department (aed) are usually assigned the task of escorting seriously ill patients to other hospitals when the need arises, either in conjunction with a paramedic or with a doctor. the aim of this study is to evaluate knowledge levels of inter-facility transport among registered nurses of the aeds in the eastern new territories of hong kong, with special emphasis on equipment preparation and management of en route adverse events. this descriptive questionnaire study took place in three hospitals located in the eastern new territories of hong kong, namely alice ho miu ling nethersole hospital (ahnh), north district hospital (ndh) and prince of wales hospital (pwh). the questionnaire was designed in four parts with questions relating to ( ) participant characteristics, ( ) general information about ift, ( ) equipment preparation and ( ) management of adverse events en route. draft questionnaires were distributed to three local experts for content validity. a pilot study was performed in the aed of another local hospital, the pamela youde nethersole eastern hospital (pyneh), to elicit feedback on the clarity and readability of the questionnaire. amendments were made accordingly following the feedback received. ethic approval was granted by the joint chinese university of hong kong -new territories east cluster clinical research ethics committee (cre- . ) prior to the commencement of this study. participation was voluntary and the questionnaires were distributed to all registered nursing staff working in the aed of the three participating hospitals. participants were expected to complete and return the questionnaires on their own during the calendar month of september . all data was anonymized for further analysis. participant characteristics as well as general information about ift were illustrated with descriptive statistics. participants' performance on the questions about equipment support and management of adverse events were scored (out of a maximum possible score of ). the mann-whitney test was used to compare participants' test scores with their clinical experience and details of any relevant courses taken. all data was entered on to an excel spreadsheet and transferred to spss for further statistical analysis. a total of questionnaires were distributed and responses were received, giving a response rate of %. five responses had to be excluded due to lack of data leaving questionnaires eligible for analysis. nine participants were senior nursing staff (nursing officer or above). twenty-six participants (more than half) had more than years clinical experience and the majority of them ( ) had received relevant training in ift. thirty-three participants had experience of using their escort kits in the past but participants indicated that the escort kit had too much equipment. thirty nurses had encountered en route adverse events during ift and the most common physiologic deterioration was systolic hypotension (n = ), followed by oxygen desaturation (n = ) and neurological deterioration (n = ). thirty-one participants had encountered equipment mishaps during transport (fig. ) . most participants were familiar with the monitoring devices available in ambulances but they were less familiar with the availability of the various airway devices. there was poor knowledge of the availability of resuscitation agents in the ambulance, specifically the drug adrenaline. a summary of participants' knowledge of items available on ambulances is shown in tables and . overall, participants' total scores ranged from to (out of ) with a mean of . ( % confidence interval . - . ). neither higher job ranking nor relevant training were associated with better participant scores. the only factor that gave rise to a statistically significant difference (median difference = . ; % confidence interval . - . ) in scores was clinical experience of more than ten years (p < . , mann-whitney test, fig. ). high quality ift is largely dependent on several factors: ( ) pre-transport preparation, ( ) equipment support, ( ) appropriateness of the transport configuration and ( ) anticipation and management of en route adverse events. pre-transport preparation comprises patient stabilization (wherever possible), communication and documentation. this study showed that % (n = ) of the participants had experienced physiological deteriorations during transport and referring facility therefore should attempt to stabilize the patient prior to dispatch as the presence of physiological instability is associated with greater risks of en route deterioration (tan, ; oakley, ; uusaro et al., ) . however, the benefits of transport may outweigh the risks in some circumstances (for example, transfer to a vascular unit for surgery for ruptured aortic aneurysm) and this principle was essentially revealed by the guidelines written by american college of critical care medicine task force ( ). a reliable communication system including physician-to-physician and/or nurse-to-nurse communication regarding patient's condition is also a fundamental principle of ift (tan, ; warren et al., ) . documentation is vital in ift not only for the quality of the transport, but also to minimize potential medico-legal issues including informed consent, a written plan from attending doctors and an en route observation record (maxwell and miller, ) . in order to supplement the role of nurses during preparatory phase of ift, pre-transport preparation should consist also of pre-transport assessment and preparation of necessary pharmacological agents for management of en route physiological deterioration (maxwell and miller, ; tan, ) . pre-transport assessment implies ensuring all equipments, intravenous lines, tubes and drains are secured and function properly as well as recording vital signs before dispatch. a multitude of equipment mishaps such as dislodged cannulae or loss of tubes can occur during ift that is also demonstrated in this survey. equipment support is a major component regarding preparatory work accountable by emergency nurses (maxwell and miller, ; tan, ; oakley, ; barbara, ) . it can be classified into two parts -escort kits and on board equipments. escort kits are usually pre-packed with minimum recommended devices (airway, monitoring and intravenous) and pharmacological agents (intravenous fluid and medication) (warren et al., ) . as in this survey, the majority of participants felt that escort kits were over-equipped. the content of escort kits commonly overlap with ambulance equipment and a crowded kit may hinder personnel from accessing necessary equipment in a timely manner. the performance of the survey participants was suboptimal with respect to knowledge of drug availability on ambulances -only % of participants could state that adrenaline was routinely stocked in ambulances. a standardized ''vehicle equipment checklist'' and ''trauma kit equipment checklist'' prepared by ambulance command, hong kong fire service department ( ) documents the equipment and drugs stored in each ambulance. future training efforts for ift in hong kong could include distributing these checklists to aed staff to improve awareness. britto et al. ( ) , etxebarria et al. ( ) and blackwell ( ) identified equipment that is often brought on board after including devices for monitoring cardiac rhythm, blood pressure and oxygen saturation; ventilatory support (ventilator and capnometry); and cardiac support (defibrillator, pacing). they should be compact, robust, vibrationresistant, clearly visible and illuminated and have adequate battery power (oakley, ) . nearly two-thirds of participants reported equipment mishaps in this survey. over a third of nurses experienced monitoring device failures and a fifth experienced venous access and endotracheal tube dislodgements during transport. equipment checks and trouble-shooting should form part of the ift curriculum for nurses in hong kong. paramedics remain the commonest provider for ift and are responsible for around % of all trans-ports according to data from quarterly audits on ift of ahnh . it remains unclear as to whether a physician or nurse should be present during ift. configurations can be nurse-paramedic or physician-nurse combination (oakley, ; blackwell, ; barbara, ) . alternative personnel or specialized transport teams may be necessary depending on specific patient conditions (mcginn et al., ; vos et al., ) . there is still no worldwide accepted standard for assigning accompanying personnel for ift (markakis et al., ) . in hong kong, training for ift is not mandatory. this study did not show the significant relationship with training which is different from other studies (tan, ; blackwell, ; uusaro et al., ) . nevertheless, training is still to be recommended for frontline staff in order to enhance and enforce their skills in an unfamiliar prehospital environmentthe noisy, vibrating and bumpy ambulance (american college of emergency physicians, ; australasian college for emergency medicine, ) . adverse events can occur anytime during transport and may affect a variety of organ systems (etxebarria et al., ; uusaro et al., ; markakis et al., ) . we found that thirty nurses had encountered en route adverse events during ift. the management of these adverse events can influence the quality and thus the outcome of transport. physiological deteriorations should be anticipated and managed appropriately if they do occur. an inter-facility transport triage guideline can practically, effectively and objectively stratify risk before actual transport thus anticipating deterioration en route (lee et al., ) . familiarity with monitoring devices and pharmacological agents are essential in ift preparedness due to their frequent use. aed staff need to be familiar with the available resources in ambulances. both well established hardware (clinical guidelines and appropriate escort kits) and competent staff with relevant training are required to minimize risks and maximize outcomes and patient safety. lau ping fat (nursing specialist, aed, pyneh) for examining the draft questionnaires for content validity and for their expert advice. the authors also thank the chiefs-of-service and department operation managers of the three aeds involved for their kind approval and genuine support for the study. ema trauma kit equipment check list. hong kong fire service department ema vehicle equipment check list. hong kong fire service department guideline committee of the american college of critical care medicine principles of appropriate patient transfer minimum standards for transport of critically ill patients provide safe passage for patients interfacility transports. seminars in respiratory and critical care medicine morbidity and severity of illness during interhospital transfer: specialized paediatric retrieval team primary trauma diversion: initial experience in hong kong guidelines on inter-hospital transport of critically ill adult patients prospective application of risk score in the interhospital transport of patients inter-facility and critical care transport medicine team interhospital transfers: decision-making in critical care areas evaluation of a risk score for interhospital transport of critically ill patients smooth the way for safe emergency transfers interhospital transfer of the critically ill trauma patient: the potential role of a specialist transport team in a trauma system interhospital transfer of the trauma patient interhospital and intrahospital transfer of the critically ill patient safe longdistance interhospital ground transfer of critically ill patients with acute severe unstable respiratory and circulatory failure comparison of interhospital pediatric intensive care transport accompanied by a referring specialist or a specialist retrieval team guidelines for inter-and intrahospital transport of critically ill patients available online at www.sciencedirect.com the authors thank mr. stones wong (president of the hong kong emergency nurses association), ms. wong lai king (department operation manager, aed, queen elizabeth hospital, kowloon) and mr. key: cord- -wb mwklo authors: cheng, vincent c.c.; wong, shuk-ching; chuang, vivien w.m.; so, simon y.c.; chen, jonathan h.k.; sridhar, siddharth; to, kelvin k.w.; chan, jasper f.w.; hung, ivan f.n.; ho, pak-leung; yuen, kwok-yung title: absence of nosocomial transmission of coronavirus disease (covid- ) due to sars-cov- in the pre-pandemic phase in hong kong date: - - journal: am j infect control doi: . /j.ajic. . . sha: doc_id: cord_uid: wb mwklo background: to describe the infection control strategy to achieve zero nosocomial transmission of symptomatic coronavirus disease (covid- ) due to sars-cov- during the pre-pandemic phase (the first days after announcement of pneumonia cases in wuhan) in hong kong. methods: administrative support with the aim of zero nosocomial transmission by reducing elective clinical services, decanting wards, mobilizing isolation facilities, providing adequate personal protective equipment, coordinating laboratory network for rapid molecular diagnosis under -tier active surveillance for hospitalized- and out-patients, and organizing staff forum and training was implemented under the framework of preparedness plan in hospital authority. the trend of sars-cov- in the first days was compared with that of sars-cov . results: up to day of the epidemic, ( . %) of , patients being screened confirmed to have sars-cov- by rt-pcr. compared with sars outbreak in , the sars-cov- case load constituted . % ( sars-cov- / sars-cov) of sars-cov infected cases at day of the outbreak. the incidences of nosocomial acquisition of sars-cov per- , -sars-patient-day and per- -sars-patient-admission were . and . respectively, which were significantly higher than the corresponding incidences of sars-cov- (zero infection, p< . ). conclusion: administrative support to infection control could minimize the risk of nosocomial transmission of sars-cov- . pandemic infection of a coronavirus disease (covid- ) due to severe acute respiratory syndrome-associated coronavirus- (sars-cov- ) was declared by world health organization (who) on march , which is days after announcement of a cluster of patients with community acquired pneumonia in wuhan, hubei province by national health commission of the people's republic of china (nhcprc), on december (day ) [ ] . on day , the covid- had already spread to countries or territories in five continents, resulting in , confirmed cases all over the world [ ] . while the epidemic of covid- is slowing down in china, there is active community transmission in europe and north america, resulting in % of disease burden is outside china [ ] . overwhelming number of covid- infections could not only paralyze the healthcare system, but more importantly, result in nosocomial outbreak, associated with increased morbidity and mortality of the hospitalized patients and healthcare workers (hcws). up to february (day ), nhcprc reported that , healthcare workers were infected with covid- , resulting in ( . %) deaths [ ] . this has exceeded the number of hcws death due sars in mainland china after months in [ ] . in hong kong, eight hcws succumbed as a result of nosocomial acquisition of sars-cov [ ] . the top priority of our pandemic preparedness is to achieve zero covid- infection among hcws in hong kong. here, we report our infection control strategy and epidemiology of sars-cov- in the first days (from the official announcement of pneumonia by nhcprc to the declaration of pandemic infection by who), using the historical data on the epidemiology of sars-cov in hong kong for comparison. after the outbreak of sars-cov in , a total of persons were infected and persons ( . %) died [ ] . of healthcare workers (hcws) infected with sars-cov in hong kong, of them ( . %) succumbed. six hcws ( doctors, nurse, and healthcare assistants) of were the employee of hospital authority, the governing body of all public hospitals, divided into cluster-networks, responsible for % of inpatient service in hong kong. a "select committee to inquire into the handling of the severe acute respiratory syndrome outbreak by the government and the hospital authority" was established by the legislative council of the hong kong special administrative region, china to in order to examine the performance and accountability of the government and hospital authority and their officers at policymaking and management levels [ ] . the report includes temporal sequence of events and daily statistics on sars patients with breakdown by healthcare workers and patients. the information is retrieved for analyzing the epidemiology of sars in [ ] . when a novel coronavirus disease, known as covid- due to sars-cov- emerged years later, hospital authority immediately activated our response plan to combat the epidemic and to prevent nosocomial transmission and outbreaks of sars-cov- . the clinical perspective of infection control measures was reported recently [ ] . the epidemiology of sars-cov- until march (at day after the official announcement of a cluster of pneumonia of unknown etiology in wuhan, hubei province, by nhcprc in hong kong) was analyzed. this is also the date when who declared the covid- pandemic. our results were compared with the epidemiological data of sars-cov at day ( april ) after the official announcement of atypical pneumonia in guangdong province, china on february . in addition, we also compared the epidemiology of sars-cov- in hong kong with hubei province, china, which is the most severe affected region by sars-cov- , and the other countries or areas with uncontrolled local transmission at day , including republic of korea, islamic republic of iran, and italy, using the publicly accessible information from the who website [ ] . after the sars outbreak in , a preparedness plan for emerging infectious diseases, including pandemic influenza and middle east respiratory syndrome-associated coronavirus, was formulated under the governance of hospital authority. the preparedness plan to combat against sars-cov- is basically referring to the framework of these plans. according to the risk assessment, the response levels can be categorized into alert level, serious response level (s ), serious response level (s ), and emergency response level [ ] . the command structure depends on the different response levels ( figure ). in the alert and s level, the response plan is coordinated by ad hoc central committee on infectious disease and emergency responses (ad hoc ccider). in the s and emergency response level, the governance will be under the command of central command committee, which is chaired by chief executive of hospital authority, or emergency executive committee, which is chaired by chairman of hospital authority. the response measures at each response level comprises of a series of action, including active surveillance and electronic notification, laboratory network for rapid molecular diagnostic, infection control measures, provision of essential medical services, facility management in the hospital, human resources and staff deployment, staff training, research, and communication. contact tracing for potential secondary cases was performed to investigate for any possible nosocomial infection as reported previously [ , ] . clinical specimens including nasopharyngeal aspirates, nasopharyngeal swabs, throat swab, saliva, sputum, endotracheal aspirates, or bronchoalveolar lavage were subjected to nucleic acid extraction by the emag extraction system (biomérieux, marcy-l'Étoile france) as previously described [ , ] . the presence of the sars-cov- rna in the specimens was first determined by the lightmix modular sebeccov e-gene commercial kit (tib molbiol, berlin, germany) and further confirmed by another in-house real-time rt-pcr assay targeting the sars-cov- rna-dependent rna polymerase/helicase gene [ ] . the fisher's exact test was used to compare independent categorical variables between groups. all reported p values were two-sided. a p value of < . was considered statistically significant. computation was performed using the spss version . for windows. up to march (day after the official announcement of a cluster of pneumonia of unknown etiology in wuhan, hubei province, a total of cases of sars-cov- infection were confirmed in hong kong, while the first patients were reported previously [ ] . with these additional cases, there were males and hcws were infected with sars. ( . %) of them were investigated for nosocomial acquisition of sars-cov in acute hospitals [ ] . the incidences of nosocomial acquisition of sars-cov per , sars-patient-day and per sars-patient-admission were . and . respectively, which were significantly higher than the corresponding incidences of nosocomial acquisition of sars-cov- (p< . ). in the first days, the incidence of sars-cov- in hong kong was . per , populations, which was lower than china (hubei province), europe (italy), asia (republic of korea, and singapore), and middle east (iran) ( table ) . upon receiving the official announcement of a cluster of pneumonia of unknown etiology in wuhan, hubei province, on december (day ), the infection control responses were stepped up by hospital authority according to the rapidly evolving epidemiology in hong kong [ ] . the level of response towards emerging infectious disease was directly elevated from alert to s on day . ad hoc ccider was regularly held among infection control professionals in clusternetworks and senior management team in the head office of hospital authority infection of healthcare workers due to occupational exposure to infectious diseases is always a great challenge to hospital administration and infection control professionals. sporadic cases of occupation related infection among hcws due to various infectious diseases such as mycobacterium tuberculosis, hepatitis b virus, and hepatitis c virus were occasionally reported [ ] . however, the impact of sars transmission among hcws was unprecedentedly high. according to who, hcws accounted for , ( %) of , cases of sars patients in [ ] . it produced a significant psychosocial effects and long-term psychological effects on hcws [ ] . therefore, when the covd- emerged, it is important to maximize our administrative resources and infection control measures to protect our hcws, which is particularly relevant in hong kong as we had hcws died in as a result of nosocomial acquisition of sars-cov [ , ] . administrative support to infection control is important to prevent nosocomial outbreak but it is not well studied in recent years [ ] . however, suboptimal administrative support was attributed to the prolonged outbreak of carbapenemaseproducing enterobacteriaceae in a tertiary care hospital in france [ ] , as well as the major outbreak of sars in hong kong [ ] . therefore, the command structure for serially updated along with the evolving epidemic of covid- [ ] . with the support of hospital administration, the infrastructure of hospitals was improved from the period of sars-cov to sars-cov- by the provision of aiirs in hong kong. early isolation of patients with sars-cov and their close contacts was found to be effective in termination of chain of transmission [ , ] when the viral load sars was peaked at day after symptoms onset [ ] . for sars-cov- , high viral load was detected soon after onset of symptoms onset [ ] . a the evolving criteria of active surveillance was reported [ ] . b aami level isolation gown is used when small amounts of fluid exposure is anticipated. aami level isolation gown can be considered when splashing is anticipated. alternatively, a waterproof apron on top of the aami level isolation gown is also acceptable (with effect from february , day ) c the fourth tier enhanced laboratory surveillance was updated since february (day ). the centre for health protection closely monitors cluster of pneumonia cases on mainland. press release of the department of health accessed world health organization exploring the reasons for healthcare workers infected with novel coronavirus disease (covid- ) in china list of medical professionals who died during the sars outbreak severe acute respiratory syndrome coronavirus as an agent of emerging and reemerging infection sars cases with onset of illness from report of the select committee to inquire into the handling of the severe acute respiratory syndrome outbreak by the government and the hospital authority daily statistics on sars patients with breakdown by healthcare workers, amoy gardens residents and others escalating infection control response to the rapidly evolving epidemiology of the coronavirus disease (covid- ) due to sars-cov- in hong kong coronavirus disease (covid- ) situation reports preparedness and proactive infection control measures against the emerging novel coronavirus in china prevention of nosocomial transmission of swine-origin pandemic influenza virus a/h n by infection control bundle infection control preparedness for human infection with influenza a h n in hong kong improved molecular diagnosis of covid- by the novel, highly sensitive and specific covid- -rdrp/hel real-time reverse transcription-polymerase chain reaction assay validated in vitro and with clinical specimens evidence/documents provided by the administration and related persons for the select committee to inquire into the handling of the severe acute respiratory syndrome outbreak by the government and the hospital authority infectious diseases in healthcare workers -an analysis of the standardised data set of a german compensation board long-term psychological and occupational effects of providing hospital healthcare during sars outbreak clinical management and infection control of sars: lessons learned the role of the hospital administrator in the control of nosocomial infections prolonged delay for controlling kpc- -producing klebsiella pneumoniae outbreak: the role of clinical management temporal profiles of viral load in posterior oropharyngeal saliva samples and serum antibody responses during infection by sars-cov- : an observatinoa cohort study the lessons of sars in hong kong sars and the removal of personal protective equipment hospitalized patients with novel coronavirus-infected pneumonia in wuhan, china center for diagnosis and treatment of infectious diseases, the ministry of education of china. all authors report no conflicts of interest relevant to this article. key: cord- -dk snw r authors: yang, lin; chan, king pan; wong, chit ming; chiu, susan shui seng; magalhaes, ricardo j. soares; thach, thuan quoc; peiris, joseph syrial malik; clements, archie c. a.; hu, wenbiao title: comparison of influenza disease burden in older populations of hong kong and brisbane: the impact of influenza and pneumococcal vaccination date: - - journal: bmc infect dis doi: . /s - - - sha: doc_id: cord_uid: dk snw r background: influenza and pneumococcal vaccine uptake in the older population aged years or over of hong kong dramatically increased since the sars outbreak. this study is aimed to evaluate the impact of increased coverage of influenza and pneumococcal vaccines by comparing the change of disease burden in the older population of hong kong, with the burden in the older population of brisbane with relatively high vaccine coverage in the past fifteen years. methods: time series segmented regression models were applied to weekly numbers of cause-specific mortality or hospitalization of hong kong and brisbane. annual excess rates of mortality or hospitalization associated with influenza in the older population were estimated for the pre-sars (reference period), post-sars and post-pandemic period, respectively. the rate ratios (rrs) between these periods were also calculated to assess the relative change of disease burden. results: compared to the pre-sars period, excess rates of mortality associated with influenza during the post-sars period in hong kong decreased for cardiorespiratory diseases (rr = . , % ci . , . ), stroke (rr = . , % ci . , . ), and ischemic heart diseases (rr = . , % ci . , . ). the corresponding rrs in brisbane were . ( % ci . , . ), . ( . , . ), and . ( . , . ), respectively. only the mortality of ischemic heart diseases showed a greater reduction in hong kong than in brisbane. during the post-pandemic period, excess rates of all-cause mortality increased in hong kong, but to a lesser extent than in brisbane (rr = . vs . ). conclusion: a relative decrease (or less of an increase) of influenza disease burden was observed in the older population of hong kong after increased coverage of influenza and pneumococcal vaccines in this population, as compared to those of brisbane where vaccination rates remained stable. the lack of significant findings in some disease categories highlights the challenges of evaluating the benefits of vaccination at the population level. electronic supplementary material: the online version of this article ( . /s - - - ) contains supplementary material, which is available to authorized users. globally, influenza has been associated with a heavy burden of mortality and morbidity [ ] . vaccination remains an important strategy to reduce disease severity and virus transmission within the community [ ] . although numerous clinical trials have demonstrated the effectiveness of influenza vaccines in children [ ] , adults [ ] , and healthy elderly people [ ] , few studies have included high-risk groups particularly the elderly with underlying chronic conditions. a recent systematic review also concluded that influenza vaccine only had a modest effect in preventing influenza infections among community-dwelling elderly people [ ] . previous cohort or case-control studies reported that vaccine effectiveness was % in preventing all-cause mortality [ ] . however, according to a study in the us, < % of all-cause mortality was specifically associated with influenza, suggesting that the estimates from the observational studies could have been seriously overestimated [ , ] . another ecological study conducted in ontario, canada also found significant relative reductions in influenza-associated mortality and health care utilization after the introduction of universal vaccination since in those aged < yrs., but not in those aged ≥ yrs. [ ] . taken together, available evidence suggests that there is a need to assess the effect of influenza vaccination at the population level, especially for those aged ≥ years. previous studies in hong kong have shown that annual vaccination rates for community-dwelling elderly people were less than % during the period - [ ] , but increased to more than % in - [ ] . since october , a subsidy of hk$ (us$ . ) for annual influenza vaccine and hk$ (us$ . ) for pneumococcal vaccine has been provided to those aged ≥ years under the elderly vaccination subsidy scheme. the vaccination rate remained nearly % in the elderly in the / season [ ] . in australia, the federal government has been providing free influenza vaccinations for people aged ≥ years since , and the coverage rates in the older population remained between and % during the period of - [ ] . unlike hong kong, where the sars outbreak and a new subsidy program greatly increased influenza and pneumococcal vaccine coverage among the older population, brisbane has had a relatively stable vaccination rate for both vaccines since . here we hypothesize that if influenza vaccine was effective in older people, the dramatically increased uptake among the older population of hong kong since sars could have resulted in a reduced influenza disease burden. we expect such a reduction to be larger than in brisbane, where uptake of the vaccine has remained stable among the community dwelling elderly people. further decrease in disease burden of influenza could have occurred after , as the increased uptake of pneumococcal vaccines in the older population could have reduced the risk of secondary bacterial pneumonia after influenza infections. hong kong is located at a latitude of °n, with a population of . million in residing in an area of km . brisbane is located at a latitude of °s, with a population of . million in and a territory of km . both hong kong and brisbane have a subtropical climate, with average temperatures of °c and °c, and relative humidity of and %, respectively. in terms of socioeconomic conditions, both are developed cities with a comparable gross domestic product per capita ($ , in hong kong vs. $ , in australia in ) [ ] . during the study period, the percentage of the population aged ≥ years was . % in hong kong and . % in brisbane. virology data, death registry data, hospital admission, and meteorological data during the study period of to were obtained from difference data sources of hong kong and brisbane, respectively. the detailed information is provided in additional file : appendix . in hong kong, seasonal influenza peaks during january -march and june -july, whereas in australia the peak usually occurs in august -october (fig. ) . given that seasonal influenza peaks at different times in these two cites, we defined annual study period as january -december in hong kong and may -april of next year in brisbane. these periods begin three months after the usual launch dates for the annual seasonal influenza vaccination campaigns (march in brisbane and september in hong kong), which shall allow for a valid assessment of the vaccination effectiveness. the whole study period was divided into the pre-sars, sars, post-sars, influenza pandemic and post-pandemic periods. the pre-sars period in hong kong was featured with a much lower vaccination rate in the older population compared to the post-sars and post-pandemic periods, whereas the vaccination rate in the older population of brisbane was stable across these periods. the burden during the sars and pandemic periods was not presented, as this was highly affected by different control measures adopted by the health authorities of hong kong and brisbane. the cut-off dates for these periods in hong kong and brisbane are listed in additional file : appendix . we constructed time series segmented regression models to estimate cause-specific mortality or hospitalization risks associated with influenza in the older population during the pre-sars, post-sars, and post-pandemic periods for hong kong and brisbane. the proxy variable for influenza in the model was the percentage of specimens that tested positive for influenza each week out of annual total number in each city. the reason why we decided to use annual percentage instead of weekly proportion used in our previous studies is that total numbers of specimens were not available in brisbane during the whole study period. we added seasonal trends, temperature, humidity, and other respiratory viruses to the model as covariates to estimate influenza-associated excess risks. dummy variables for the pre-sars, post-sars, and post-pandemic periods, together with the interaction terms between these period dummies and the virus activity variables, were also added to test the statistical differences in risk estimates between the different periods, respectively for hong kong and brisbane. the best-fit models were chosen by the minimal generalized cross-validation (gcv), according to our previous study [ ] . baseline rates of cause-specific mortality and hospitalizations associated with influenza were calculated for different periods by setting the virus proxy to zero and the corresponding period dummy to one (other dummies were simultaneously set to zero). we first estimated excess numbers by subtracting baseline rates from the observed data, and calculated excess rates (er) by dividing the excess numbers with age-specific population size. we calculated the % confidence interval (ci) of er by bootstrapping times. because the periods were of different lengths, annual excess rates (aer) of mortality (or hospitalizations) were calculated to facilitate comparisons between different periods. for each disease category, the rate ratios (rrs) of post-sars (or post-pandemic) versus pre-sars were derived by dividing annual excess rates during the post-sars (or post-pandemic) period with those of the pre-sars period (as reference): rr = aer (post-sars) / aer (pre-sars). since the pre-sars period was treated as the reference period in this study, hereafter the post-sars rr refers to the risk ratio of mortality or hospitalization in the post-sars period relative to those in the pre-sars period. similarly, the post-pandemic rr refers to the risk ratio of mortality or hospitalization in the post-pandemic period relative to those in the pre-sars period. the % ci and p-value of rr were derived from a normal approximation of their logarithmic transformations [ ] . we also conducted a subset analysis by using the data of influenza peak seasons only. the influenza season was defined as january to july in hong kong, and may to november in brisbane. we conducted another subset analysis by excluding the data for the mismatched years ( , , and in this study). all of the analyses were conducted in r software version . . . the significance level was set to . for all analyses. during the study period, there were around , and , people older than years living in hong kong and brisbane, respectively (tables and ). compared to hong kong, during the study period brisbane had higher mortality rates for all-cause ( . vs . per , population), cardiorespiratory diseases (crd, . vs . ), stroke ( . vs . ) and ischemic heart diseases (ihd, . vs . ), but a lower rate for pneumonia and influenza (p&i, . vs . ), and a comparable rate for chronic obstructive pulmonary disease (copd, . vs . ) (additional file : appendix ). all the cause-specific hospitalization rates were much lower in brisbane than in hong kong ( . vs . per , population for crd, . vs . for p&i, . vs . for copd, . vs . for stroke), with the only exception of ihd ( . vs . ) (additional file : appendix ). hong kong and brisbane have opposite seasonal climate patterns; the former is located in the northern hemisphere and the latter in the southern hemisphere. mean temperature and relative humidity of brisbane were lower than those of hong kong (additional file : appendix ). compared to the pre-sars period, average number of hospitalizations in hong kong was lower in the post-sars period for most disease categories, with the exception of a three-fold increase in p&i hospitalizations. this significant increase is likely due to the change in coding practice after the sars outbreak (table ). average number of hospitalizations was higher in the post-pandemic period for all the disease categories. weekly figures for mortality and hospitalization in brisbane did not obviously differ across the pre-sars, post-sars, and post-pandemic periods ( table ) . due to negative estimates in the annual excess rates for mortality, the post-sars rr could not be estimated for ihd hospitalizations in hong kong, and p&i mortality, stroke, and ihd hospitalizations in brisbane. similarly, the post-pandemic rr could not be estimated for p&i and ihd hospitalization in hong kong, and stroke and copd hospitalization in brisbane (additional file : appendix ). influenza-associated all-cause mortality rates were found increased after sars in hong kong (post-sars vs pre-sars rr = . ) but decreased in brisbane (rr = . ). the post-sars copd mortality increased in both cities ( . and . in hong kong and brisbane, table ). decreased excess rates of mortality in hong kong were observed for crd, stroke, and ihd mortality (rr = . and . ), while the corresponding rrs in brisbane were . and . , respectively. only ihd mortality had a greater reduction observed in hong kong than in note. weekly positive percentage (%) is defined as the percentage of positive specimens among annual total specimens brisbane (rr = . vs . ). none of rr estimates for the control disease injuries were significant (data not shown). compared to the pre-sars period, excess rates of crd hospitalizations in the post-sars period decreased in hong kong, but increased markedly in brisbane (rr = . vs . ). influenza-associated hospitalizations for p&i and copd increased more in brisbane than in hong kong (rr = . vs . and . vs . ). compared to the pre-sars period, excess mortality rates increased in hong kong for all the disease categories except for ihd, but only all-cause and copd mortality increased in brisbane. difference between hong kong and brisbane was found statistically significant for all-cause and stroke mortality. annual excess rates of all-cause mortality increased in hong kong to a lesser extent than in brisbane (rr = . vs . ), whereas an opposite trend was observed for stroke mortality (rr = . vs . ). subset analysis with peaks seasons only, or vaccine matched years only, generally derived larger rr estimates ( table ). the estimates for crd became significantly higher than one, and the brisbane estimates were much greater than the hong kong ones. many outcomes could not be estimated due to negative values of excess rates. in this study, we estimated excess rates of mortality or hospitalizations attributable to influenza in different periods (pre-sars, post-sars, and post-pandemic) for two subtropical cities hong kong and brisbane. we hypothesized that the influenza disease burden decreased more, or increased less, in hong kong than in brisbane since , because the uptake rate of influenza and pneumococcal vaccines increased more markedly in hong kong than in brisbane during the same period. kwong et al. [ ] compared the relative change of disease burden in ontario, where a universal influenza vaccination program was launched, to that in other canadian provinces without such a policy. they found that influenza-associated mortality fell in ontario and other provinces, but a larger reduction occurred in ontario. in this study, we found that excess rates of ihd mortality decreased more from the pre-sars to the post-sars period in hong kong than in brisbane, but with regard to the other mortality outcomes, excess rates increased more in hong kong. with respect to hospitalization in the post-sars period, significantly lower excess rates were only found for crd in hong kong. p&i and copd hospitalization rates increased in both cities, but to a lesser extent in hong kong. many countries have recommended annual influenza vaccination or providing subsidy programs to the older note. weekly positive percentage (%) is defined as the percentage of positive specimens among annual total specimens population [ ] . however, due to ethical concerns, a large body of knowledge on the effectiveness of influenza vaccine in the older population has been derived from observational studies, as few randomized controlled trials have been conducted in this high-risk population. a review by goodwin et al. found that seroprotection and seroconversion achieved in the older population after vaccination was only - % of vaccine response in younger adults [ ] . a cochrane review concluded that influenza vaccines were of limited effects, which could probably be explained by weak antibody response in the older population [ ] ; however, in a recent reanalysis using the same data, walter et al. made the opposite conclusion [ ] . they estimated that influenza vaccine resulted in a % reduction in complications after influenza infections, % in influenza-like illnesses, and % in laboratory confirmed influenza infections, specifically during influenza epidemics. however, there is still an on-going debate on vaccine effectiveness in the older population. our findings add some evidence of a decrease, or a slow increase, in influenza-associated disease burden among the older population, following a marked increase in influenza vaccine coverage at the population level. however, it should be noted that this effect could have been partially caused by an increase of pneumococcal vaccination at the same time. given that the effectiveness of influenza vaccine is affected by many factors including pre-existing immunity, antigenic shift, and underlying condition, it is not surprising that we failed to find consistent and significant estimates. this also highlights the challenges of evaluating the benefits of vaccination at the population level, even in the most susceptible older populations. a higher disease burden was found in both hong kong and brisbane after , which was consistent with the findings of our previous studies and others [ , ] . the potential explanation could be that h n was more often predominant after and this subtype has been found associated with higher disease burden than h n and b. the point estimates of rrs were sensitive to modeling parameters, and most had wide confidence intervals. this could be due to only a relatively small proportion of deaths or hospitalizations attributable to influenza. according to our previous studies, each year influenza is associated with nearly deaths and , hospitalizations in hong kong, accounting for only and % of annual total deaths and hospitalizations, respectively [ ] [ ] [ ] [ ] . negative estimates of excess rates were occasionally derived from some disease outcomes, making it difficult to assess the relative increase/decrease between two cities. relatively small counts in brisbane could be the reason why we obtained extremely large or small point estimates for the post-sars rr of crd hospitalizations and the post-pandemic rr of stroke mortality in brisbane; hence, these rrs need to be interpreted with caution. unfortunately, good quality mortality, hospitalization, influenza surveillance and vaccination data are available in few subtropical countries/regions. nevertheless, this study is the first to investigate the effectiveness of influenza and pneumococcal vaccination at the population level in warm climates, to our best knowledge. there are several limitations in this study. first, ecological fallacy is unavoidable given the ecological study design. individual vaccination status of those who have died or been hospitalized is unknown and the outcome variables are not specific to influenza. nevertheless, we have used a previously validated modeling approach to estimate disease burden associated with influenza. second, we assume that circulating influenza strains and pre-exisitng immunity at the population level are similar between hong kong and brisbane. therefore, a relative decrease (or less of an increase) in influenza-associated disease burden could reflect the effectiveness of influenza vaccination in terms of reducing adverse outcomes after influenza infections. this assumption may not hold, but there is also no strong evidence against it. third, only two to five years of data were included in each study period, because influenza virology and hospitalization data prior to were not available in hong kong or brisbane. our model obtained some unstable points estimates, especially in the pre-sars period, which could be due to the short time series and low counts. last but not least, although we have carefully adjusted for seasonal trends, temperatures, and humidity in our models, there are many confounding factors that remain unadjusted for in this study, such as the prevalence of underlying condition, and difference in health-seeking behaviors between two older populations. in conclusion, we found some but limited evidence that markedly increased rates of influenza and pneumococcal vaccination among the hong kong older people did lead to a reduction in their influenza disease burden. however, furture cohort studies with individual data are warranted to provide stronger evidence to support the promotion of influenza vaccination among the older population. additional file : appendix . additional information on data sources and statistical analysis. appendix . study periods defined for hong kong and brisbane. appendix . time series plots of weekly numbers of cause-specific mortality data of hong kong (black line) and brisbane (gray line). emerging infections: pandemic influenza influenza vaccines assessment of the efficacy and effectiveness of influenza vaccines in healthy children: systematic review vaccines for preventing influenza in healthy adults efficacy and effectiveness of influenza vaccines in elderly people: a systematic review vaccines for preventing influenza in the elderly effectiveness of influenza vaccine in the community-dwelling elderly mortality benefits of influenza vaccination in elderly people: an ongoing controversy impact of influenza vaccination on seasonal mortality in the us elderly population the effect of universal influenza immunization on mortality and health care use immune response to influenza vaccination in community-dwelling chinese elderly persons preliminary findings of a randomized trial of non-pharmaceutical interventions to prevent influenza transmission in households seasonal influenza vaccination coverage survey for the / season australian institute of health and welfare international monetary fund: world economic outlook database model selection in time series studies of influenza-associated mortality modern epidemiology influenza vaccination in : recommendations and vaccine use in developed and rapidly developing countries antibody response to influenza vaccination in the elderly: a quantitative review cochrane re-arranged: support for policies to vaccinate elderly people against influenza excess mortality associated with influenza a and b virus in hong kong excess mortality associated with the pandemic of influenza a(h n ) in hong kong age and sex differences in rates of influenza-associated hospitalizations in hong kong dietary habits and the short-term effects of air pollution on mortality in the chinese population in hong kong influenza-associated hospitalization in a subtropical city we thank the census and statistics department, hospital authority of hong kong, hong kong observatory, australian bureau of meteorology, australian institute of health and welfare, department of health of the australian government, and queensland health australia for providing the datasets used in this study. this study was supported by health and medical research fund (grant number: ), from the research fund secretariat, food and health bureau, the government of the hong kong special administrative region. the study sponsor was not involved in study design, data collection, analysis, and interpretation of data; nor in the writing of the report and in the decision to submit the paper for publication. the corresponding author had full access to all the data in the study and had final responsibility for the decision to submit for publication. administrative permissions from the data providers were required to access the raw data provided by the census and statistics department, hospital authority of hong kong, australian institute of health and welfare, department of health of the australian government, and queensland health australia). meteorological data are available at the websites of the hong kong observatory and australian bureau of meteorology. the r scripts used in this study are available from the corresponding author on request.authors' contributions ly, cmw, sssc, jsm and wbh designed the study and collected data. ly and kpc conducted data analysis and drafted the manuscript. sssc, rjsm, tqt, acac and wbh interpreted the results and finalized manuscript. all the authors gave final approval of the version to be published.ethics approval and consent to participate because no personal data was collected, individual consent was not required. the ethical approval was obtained from the institutional review board of the university of hong kong/hospital authority hong kong west cluster (reference number uw - ) and from the departmental research committee of the school of nursing, the hong kong polytechnic university (reference number hsears ). not applicable. the authors declare that they have no competing interests. springer nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. key: cord- -cvlq i c authors: li, mimi; fang, lei; huang, xiaoting; goh, carey title: a spatial–temporal analysis of hotels in urban tourism destination date: - - journal: int j hosp manag doi: . /j.ijhm. . . sha: doc_id: cord_uid: cvlq i c this study investigates the spatial associations of urban tourism phenomena by using gis and statistical methods to examine the relationships between hotels and land use types, attractions, transportation facilities, and the economic variables of the tertiary planning units in which the hotels are located. hong kong is used as an example. the study first introduces the spatial characteristics of hotels and attractions development in hong kong. a geographical information system is then used to map hotels and investigate the characteristics of the land use, attractions, and transport facilities around hotels. the spatial relationships are then analyzed with a set of logistic regression models. the results reveal that commercial land type and the number of attractions around hotels are significantly related to the distribution of upper-grade hotels in hong kong. the determinants vary over time and the spatial structure changes accordingly. the analysis is important theoretically as it enriches the methodologies for analyzing the relationships between hotels and urban structure, and for conceptualizing and identifying tourism functional zones. it is important for practitioners as it provides useful information for selecting sites for hotels. interest in urban tourism has grown since the s when it was first recognized as a distinct field (edwards et al., ) . within the field, the spatial structure of tourism in cities has been an important research area (pearce, ) , focusing on the ways in which phenomena are arranged in space, and how this affects urban tourism planning and design applications. one important research direction is to empirically analyze the distribution of tourism-related phenomena, such as selected attractions, supporting facilities (pearce, ) , and accommodations in general, hotels in particular. these studies have identified distinct distribution patterns of particular tourism sectors in certain parts of cities, the most notable being clustering and linear patterns; these patterns can be explained by factors such as accessibility, land rent, planning restrictions, comparative shopping, and proximity to other tourism-related phenomena (ashworth and tunbridge, ; pearce, pearce, , . however, previous studies have largely focused on the influence of the surrounding environment on the selected tourism sector, and have not fully addressed the interactions and associations between all of the urban tourism phenomena. the current study is therefore carried out to use geographical information system (gis) tools and statistical models to investigate the spatial associations of urban tourism phenomena by examining the spatial relationships between hotel distribution and land types, attractions, and other surrounding environmental factors in hong kong. more specifically, this study attempts to ( ) analyze the factors that affect the location strategies of upper-grade hotels; and ( ) identify factors that influence changes in spatial patterns after a hotel's establishment. to achieve these objectives, the association between the level of hotels and the environmental characteristics around the hotels from to are investigated using a set of logistic models. cities have been among the most significant tourist destinations since urbanization began (edwards et al., ; karski, ) . nowadays, tourism occupies substantial amounts of space within urban destinations via tourist-historic urban cores, museums of all kinds, urban waterfronts, theme parks, and specialized precincts (edwards et al., ) . however, before the s, studies of urban tourism were fragmented and it was not recognized as a distinct http://dx.doi.org/ . /j.ijhm. . . - /© elsevier ltd. all rights reserved. field (edwards et al., ) . an upsurge in interest in urban tourism was sparked by ashworth's work in , in which he stated that ". . .the failure to consider tourism as a specifically urban activity imposes a serious constraint that cannot fail to impede the development of tourism as a subject of serious study" (ashworth, : ) . in his pioneer work, ashworth ( ) outlined four extant approaches to analyzing urban tourism: ( ) the facility approach, which focuses on the spatial analysis of the location of tourism attractions, facilities, infrastructure, and zones; ( ) the ecological approach, which focuses on the structure and morphology of urban areas and features the identification of functional zones or districts such as central business districts (cbd); ( ) the user approach, which adopts a marketing perspective focused on tourists; and ( ) the policy approach, which is concerned with a range of policy issues including infrastructure provision and destination marketing (ashworth, ) . establishing the spatial structure of tourism in cities has been an ongoing concern within the urban tourism research field from an early stage (pearce, ) . from a supply-side perspective, this reflects an inherent interest in the ways in which phenomena are arranged in space, and the implications for urban tourism planning and design applications. two broad approaches are taken to this issue: ( ) empirically analyzing the distribution of tourism-related phenomena, especially accommodation; and ( ) conceptually examining the existence and functioning of tourist districts, particularly with regard to heritage and planning. most of the distributional studies have focused on one particular sector of the tourism industry, most commonly on accommodation and hotels. the distribution of selected attractions and supporting facilities has also been examined in these studies (pearce, ) . the studies carried out to date have established distinct distribution patterns, particularly clustering and linear patterns, in tourismrelated phenomena in certain parts of cities. the distribution pattern of a city's tourist phenomena can be explained by factors such as accessibility, land rent, the recency effect, planning restrictions, comparative shopping, and proximity to other tourism-related phenomena (ashworth and tunbridge, ; pearce, pearce, , . based on previous studies, pearce ( ) outlined an integrative framework for urban tourism and illustrated applications with reference to selected aspects of the literature. the framework emphasized the identification of subject cells within a matrix defined in terms of scale (site, district, city-wide, regional, national, and international) and themes (demand, supply, development, and impacts). for instance, rigall-i-torrent et al. ( ) examined the effects of beach characteristics (such as beach length, width, sand type, or beach services) and distance of a hotel from the beach on sun-and-beach hotel prices at the regional level. a study at the city level by yang et al. ( ) investigated potential factors contributing to hotel location choice in beijing by incorporating both hotel and location characteristics. they found that star rating, years since opening, service diversification, ownership, the agglomeration effect, public service infrastructure, road accessibility, subway accessibility, and accessibility to tourism sites are all important determinants. while ruggero and rodolfo ( ) found that structural social capital is the strongest positive determinant of hotel performance, compared with weaker and generally not significant relations linking occupancy and control variables, such as category, size, location. our review of the distributional literature identified two research gaps. first, current studies have failed to provide an integrated interpretation of how tourism in an urban area is related to surrounding spatial elements such as land use types, and therefore the spatial associations were not well explained. second, few studies have examined the temporal variations in the spatial relationships between hotel location and surrounding environmental factors. gis is a useful tool for tackling these research problems. geographical information systems (gis) have been used to develop a number of applications for tourism that allow the analysis of regional information (poslad et al., ) . they can be divided into two basic categories: (a) spatial decision support applications and (b) spatial statistics support applications. the former uses gis systems that are specifically designed to handle spatial relationships to integrate four types of relevant data: tourist characteristics (e.g., lau and mckercher, ) , actual temporal-spatial behavior (e.g., shoval et al., ) , landscape elements and tourist locations (e.g., brown, ) , and the images added to these locations (e.g., gaughan et al., ) . then, a decision-support model is added to the gis to analyze the overall temporal-spatial behavior and to obtain some optimal conclusions (bahaire and elliott-white, ; beedasy and whyatt, ; bertazzon et al., ; boers and cottrell, ; brown, ; dye and shaw, ; gaughan et al., ; lau and mckercher, ; perez et al., ; shoval et al., ; van der knaap, ) . the second type of application uses gis not only to integrate data, but also to analyze the spatial patterns of tourism (allen et al., ; atasoy, ; farsari and prastacos, ; porter and tarrant, ) . allen et al. ( ) developed a parcel-based gis model for assessing land-use change in the past; they built a spatial multivariate logistic regression model and selected variables to predict the possibilities of land-use change for murrells inlet, south carolina. however, the study focused on land-use change in a coastal tourism destination area without investigating the relationship between tourism phenomena and the changes in land use. hotel location selection is a critical element of destination management strategy. the understanding of the determinants of hotel location selection is key to ensure coherent spatial planning at tourism destinations (issahaku and francis, ) . according to previous studies, the main research approach used to explain location choices and spatial patterning of hotels are regression methods based on economic theory (e.g., zhang et al., ; yang et al., ) . the explanatory variables in these regression models are related to labor, culture, capital, and policy characteristics. in addition, as the hotel industry is closely linked to the real estate industries, which are significantly driven by economic conditions and external events, factors that affect these industries should be included in the analysis of the location of hotels (e.g., yang et al., ) . for instance, porter and tarrant ( ) identified and examined inequalities in federal tourism sites and campsites in southern appalachia based on five socioeconomic variables including race, education, household income, occupation, and local heritage. spatial characteristics are also regarded as important determinants of hotel locations. tourism accommodation comprises a bundle of private attributes located in a specific physical environment which embeds public attributes, such as natural environment, public safety or cultural heritage (albert et al., ) . seul ( ) found that hotels compete with more distant neighbors of similar quality than those who are quality-differentiated. in addition, the results also suggest possibility of cooperation among neighboring hotels similar in quality. to increase the demand, hotels are likely to be located in places that are proximate to their potential markets. they are usually highly clustered so as to obtain benefits from agglomeration effects. barros ( ) found that hotels close to their potential markets are more efficient than their counterparts that have poor accessibility. a model proposed by yokeno ( ) indicated that in a mono-centric city, spatial centrality is observed among hotels, due to the large demand for accommodation in the city center such as the central business district (cbd) or the tourist district (yokeno, ; shoval, ) . weaver ( ) argued that this is because tourists prefer a location where a variety of services are available. accessibility to tourist attractions (arbel and pizam, ) and transportation facilities (wall et al., ; ashworth and tunbridge, ) were also found to be important factors influencing hotel locations. this was supported by rigall-i- fluvià ( , ) , who pointed out that hotel products and other tourism-related products can be viewed as bundles of public and private characteristics or attributes, and that the public attributes include characteristics of public good, such as non-rivalry and nonexcludability (samuelson, ) . some examples of attributes that contribute to the public good include, but are not limited to, environmental quality, public safety, public infrastructure availability, and cultural diversity. therefore, these attributes and services are believed to influence both the tourists' utility functions on the demand side and the tourism agents' production functions on the supply side (rigall-i-torrent and fluvià, ) . rigall-i- fluvià ( , ) argued that the supply of attributes related to the public good and services influence hotel's room rates, and hence, generate higher revenue for hotels near rich public infrastructures. based on this argument, hotels are likely to choose locations with a high rate of public good and an abundant supply of services. moreover, a recent study by yang et al. ( ) investigated potential factors contributing to the choice of hotel location with an ordered logit model that incorporated both hotel and location characteristics. they found that factors such as hotel star rating, years since opening, service diversification, ownership, the agglomeration effect, public service infrastructure, road accessibility, subway accessibility, and accessibility to tourism sites are important determinants. it is indirectly suggested that within the metropolitan area, there is a greater degree of substitution in hotel locations for tourism consumers than for business consumers (jacint and josé, ) . to investigate the spatial associations of urban tourism phenomena, a set of logistic models is used with the assistance of arcgis . . we selected hong kong as an example because hong kong is a typical urban tourism destination. tourism in hong kong has developed dramatically since , when the hong kong tourist association (now known as the hong kong tourism board) was constituted, and the city has now established itself as an internationally renowned destination. according to the most recent statistics released by euro monitor international ( )the world's leading independent provider of business intelligence on industries, countries, and consumers -hong kong was ranked as the top city tourism destination in . one of the major characteristics of tourism in urban areas is that it is only one of many functions fulfilled by a city. tourists share or compete with local residents for many spaces and services (hammes, ) and the competition is particularly intense in hong kong which has scarce resources. unlike many other urban tourism destinations, hong kong's compact nature restricts its capacity to expand to suburban areas, and all development is confined to the limited land available. this makes hong kong a suitable place to conduct the study as the spatial and functional association between tourism-related phenomena and their surrounding environment is more evident and intense. the variables in this study include the level of hotels, commercial land area (cla), traffic land area (tla), the number of mtr stations (nmtr), the land use mix index (lud), gross floor area of commercial use (gfa), and the number of attractions (an). the variables were identified based on the literature review, as discussed in the previous section. all of the attractions were divided into four categories: natural (n an), man-made (m an), cultural (c an), and shopping (s an), according to the classification rules of the hong kong tourism board (table ) . the study uses all the hong kong hotels built during the - period. the names of the hotels were taken from the statistics of the hktb and the census and statistics department of the hong kong special administrative region (hereafter 'hksar') and the address of each hotel was taken from the hotel's website. the address matching method of the gis software was used to plot the hotels on the map. the hong kong tourism board of hksar divides the hotels in hong kong into three classes (hktb, a (hktb, , b (hktb, , c (hktb, , : high tariff a hotels, high tariff b hotels, and medium tariff hotels. for this study, the level of the hotels, the dependent variable, is further categorized into lower-grade hotels (representing medium tariff hotels) and upper-grade hotels (high tariff a and high tariff b hotels). cla and gfa represent market demand and market size, both of which may have positive effects on the location of hotels because they directly affect the occupancy rates. as tourists are likely to choose hotels near traffic facilities, we also investigate the effect of traffic by incorporating tla and nmtr. in addition, one of the purposes of a hotel is to provide accommodation for leisure tourists who are interested in shopping and sightseeing (yang et al., ) . therefore, the attractions around hotels in hong kong may be positively related to hotel location (arbel and pizam, ; shoval, ) . lud represents the diversity and complexity of land use types that may, to a large extent, reflect the complexity of business activities in an area. the effect of mega-events such as international festivals and sports competitions on the tourism industry has also drawn much attention from researchers. the main argument is that these megaevents affect local tourism and the local economy (e.g., burgan and mules, ; lee and taylor, ; malfas et al., ) . cities compete for the opportunity to host events that draw large crowds of visitors because such visitors tend to spend a great deal in hotels and restaurants. as hong kong's hosting of the equestrian competitions at the olympic games may have affected the spatial distribution of star hotels, the influence of mega-events is also explored in this research. it should be pointed out that some factors such as socio-economic variables that may also affect the spatial distribution of hotels are not included in the model. however, the influence of socio-economic factors will be to a large extent reflected in the changes in land use patterns. the land use data ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) were extracted from paper maps of land utilization in hong kong; the data are compiled from the planning department of the hksar and other relevant sources including spot satellite images. the transformation from a paper map to a digitized vector map was performed using envi, which is the premier software for processing and analyzing geospatial imagery. as mentioned above, previous studies have found that commercial and traffic land use types may have significant close relationships with hotel locations. hence, this study focuses on these two land use types and broadly divided the land use data into three categories (commercial, traffic, and other). the area surrounding each hotel is defined using buffers with a -m, -m, or -m radii. by overlaying land use and buffers with gis data, we are able to derive the land utilization in the environment surrounding each hotel. the net area of each land use type (commercial and traffic) is then calculated. the land use mix is calculated based on the simpson diversity index. this is a biological diversity measurement that evaluates the number of land use categories within a neighborhood. following the formal expression of the index, the land use diversity, denoted as lud, can be calculated by where n is the total number of land use types and ni is the number of land use types in the ith category. after identifying the land utilization within the buffer zones, lud is calculated using eq. ( ). as comprehensive floor use data within each buffer zone are not available, the floor use variable is introduced into our model at the tertiary planning unit (tpu) level. the tpu system is devised by the planning department of hksar for town planning and population census purposes. the tpu in which each hotel is located can be considered the surrounding area of the hotel. due to data availability, gfa in the tpu is treated as a proxy variable. the number of mtr stations is calculated by counting the stations within the buffer zones using the gis. according to the classification rules of the hong kong tourism board, the attractions are divided into four categories: natural, man-made, cultural, and shopping. the number of attractions is calculated by counting the attractions within the buffer zones using the gis. as an example, table shows the descriptive statistics for the independent variables in . the relationships between the level of hotels and various factors are investigated using logistic regression models. in particular, to investigate the temporal effects, a set of models is established for each year. sensitivity analysis is also performed for the m and m buffer radii. we choose m, m, and m as roughly equal to , , and min walking distances at an average walking speed of around m/s. logit regression is a type of regression analysis used for predicting the outcome of a categorical dependent variable based on one or more predictor variables. that is, it is used to estimate the empirical values of the parameters in a qualitative response model. the probabilities describing the possible outcomes of a single trial are modeled, as a function of the explanatory (predictor) variables, using a logistic function. frequently (and subsequently in this study) "logistic regression" is used to refer specifically to a problem in which the dependent variable is binary; problems with more than two categories are referred to as multinomial logistic regressions or, if the multiple categories are ordered, as ordered logistic regressions. logistic regression measures the relationship between a categorical dependent variable and one or more independent variables, which are usually (but not necessarily) continuous, by using probability scores as the predicted values of the dependent variable. its function can be expressed as and equivalently where p denotes the probability that the dependent variable equals , ln p/( − p) refers to the linear function of explanatory variables, x i , ˇ is the intercept from the linear regression equation (the value of the criterion when the predictor is equal to zero), ˇix i is the regression coefficient multiplied by some value of the predictor, and base e denotes the exponential function. the dependent variable of the binary logistic model is the level of hotels with = being upper-grade hotel (high tariff a and high tariff b hotels), and = being lower-grade hotel (medium tariff hotels). in this study a positive coefficient indicates that increasing the value of the variable would increase the chance of the hotel being an upper-grade hotel, whereas a negative coefficient value means the hotel is more likely to be lower grade when the value of the variable is increased. the independent variables are defined and measured as follows: where t means the variables at time t. the proposed model for this according to the tourism statistics for the to period, the number of hotels increased from in to in , with a peak growth of hotels in (see fig. a ). growth peaks of upper-grade hotels are observed in , . of the hotels that existed in , are upper-grade and are lower-grade hotels. fig. shows the spatial distribution of hotels in . visually, the hotels concentrate in the central districts (e.g., the yau tsing mong and wan chai districts). the hotel locations reveal two main trends. first, there is continuous development in the central business district (cbd). second, the hotels are expanding into surrounding districts. this pattern is related to the urban structure of hong kong. older urban areas of hong kong are to the north of hong kong island and tsim sha tsui; between and hong kong began to develop nine new towns to cope with population growth. due to the limited land resources, a large part of the rural land cannot be easily changed to other land use types (e.g., cargo port back-up or large development areas). thus, urban areas have grown slowly since and the city now has a relatively stable spatial pattern (fig. ) . in order to ensure the stability and accuracy of model, multicollinearity test has been conducted before the logistic regression analysis. in the correlation matrix of independent variables, correlation coefficient between nmtr and s an is . , which is the biggest of all the correlation coefficients. in order to confirm this conclusion, tolerance is used to test multicollinearity among the variables. the results show that the minimum value of tolerance is . , which is still higher than the lower limit value . . hence, the logit regression could perform as multicollinearity among the variables being acceptable. table presents the estimation results of models in selected years. as expected, the results of all of the models consistently show that the cla is statistically significant, indicating that shopping and business facilities play important roles in determining the location of upper-grade hotels. as for the variables capturing the location attributes, the negative coefficient of an suggests that the level of hotel has a negative relationship with the distance to attractions, perhaps because it is difficult for investors to establish hotels near natural and cultural attractions due to the resources constraint policies in hong kong. upper-grade hotels are more likely than lower-grade hotels to be closer to the commercial and business areas, rather than to attractions, suggesting that business facilities and shopping play an important role in determining the location of upper-grade hotels in hong kong. however, the negative coefficient of s an, which represents distance to shopping attractions, suggests that super shopping centers impose exclusivity obligations and thus investors cannot change land use in surrounding areas to build upper-grade hotels. it also can be inferred that the upper-grade hotels are located closer to secondary level shopping malls than to super shopping centers. compared to many urban destinations in europe or mainland china, hong kong suffers from a lack of major historical and heritage sites and landmarks. the tourism industry in hong kong therefore relies heavily on business travelers, vfr tourists (those visiting friends and relatives), and tourists who come to take advantage of the shopping facilities (zhang and lam, ; heung and cheng, ) . deniz et al. ( ) investigated perceptions of visitors to hong kong (hk) toward the corporate social responsibility practices of its four-and five-star hotels, results show that environment and mission and vision are the two most important factors affecting service quality, preference to stay, willingness to pay, and brand image. these findings suggest that upper-grade hotels will continue to be established in the commercial and business areas in the future. cla accounts for more than % of the total area in the m buffer zones of most ( %) upper-grade hotels, implying that upper-grade hotels are located in areas with a greater share of commercial land use. to predict the possible location of new uppergrade hotels, we assign a set of random circles with meters radii to identify high density commercial and business areas and repeatedly scan all of hong kong. the circles in fig. delineate possible future locations of upper-grade hotels, calculated using the floating catchment area method (fca) (morrill and earickson, ) . these circles can be regarded as a "constraint window". most hotels are located in this window due partly to land use policies that result in a much stronger hotel agglomeration effect, as land is limited. because of the tourism demand, competition or cooperation between hotels in hong kong is stronger than in other cities. it is also interesting to note that tla and nmtr are not statistically significant. the results show that there is no difference between lower-grade and upper-grade hotels in terms of traffic accessibility. hong kong has highly convenient transport facilities giving each hotel access to potential tourism markets without needing extra accessibility. thus traffic accessibility might not be an important consideration for establishing upper-grade hotels in cities with highly convenient transport facilities. the discrete choice model explains hotel location choice based on the economic principle of utility maximization. it suggests that when hotel investors are facing a spectrum of choices of different locations, they are going to pick the most desirable location to maximize its associated utility subject to certain constraints (yang et al., ) . the non-significance of the land use diversification indicator (lud) shows that the establishment and operation of upper-grade hotels are not dependent on diversity of land use. compared to the significance of cla, the non-significance of gfa is interesting. cla is the area of land zoned for commercial use surrounding hotels, whereas gfa is the gross floor area for commercial use in a tpu. theoretically, both of them should be strongly correlated as the former is the basis of the latter. the difference might be partly attributed to the way we collected the data. the gfa data are collected at the tpu level. upper-grade hotels may be established in the most prosperous parts of a tpu, where commercial land is clustered, making the relationship between cla and hotel location significant. when calculating gfa, we not only include the floor space of commercial and business buildings, but also some residential buildings, because in hong kong many buildings have shops on the lower floors and dwellings on the higher floors. these types of shops might not be any more attractive to upper-grade hotels than to lower-grade hotels. furthermore, many shop owners rent space on higher floors to operate shops, the so-called "upstairs shops." obviously, tourists are unlikely to purchase goods in these shops. models - provide a chronological analysis of the factors influencing the spatial distribution pattern of hotels. models - can be regarded as the cross-sectional data of model . the estimation results of models - give information on the annual changes in hotel spatial patterns. fig. illustrates the changes in the coefficients shown in table . the effect of commercial land use type on the spatial distribution of upper-grade hotels increased year by year from until it reached a peak in . after standard errors are in parentheses. intercepts are not reported for simplicity. * significant at the . level. ** significant at the . level. *** significant at the . level. according to the statistical data of the hong kong tourism board, is usually regarded as the peak period of tourism development in hong kong (hktb, ) . our findings show that in , commercial area had the closest spatial association with uppergrade hotels, indicating that most upper-grade hotels are located in commercial areas. in addition, as the effect of severe acute respiratory syndrome (sars) gave rise to atypical travel and spending patterns in , there was a low growth rate in new hotels established in (see fig. ). this trend is not seen in the spatial patterns of hotels and their surrounding environments, indicating that the spatial pattern in the development of hotels is not sensitive to mega-events. in this study, we use the year in which a hotel is built to identify its establishment period, and the years when the hotel is open for business as the operation period. the determinants for upper-grade hotels in their operation period are investigated in models . the estimation results are used to examine how various factors effecting hotel spatial patterning change overtime during the operation period (model ). the results of models (see table ), we find that some factors, such as land use mix, become significantly related to the spatial patterns of the hotels, suggesting that the operation of hotels influences the land use pattern. to determine the influence of spatial patterns on upper-grade hotels, the results of one model under different buffer radii are compared (see table ). we find that the significance levels and coefficients have small changes when the buffer radius is increased from m to m. this indicates that the spatial pattern of hotels and their surrounding environments is stable within the -m buffer. however, when the buffer radius is increased from m to m, the coefficients change significantly. perhaps, when establishing a hotel, an investor focuses on the spatial structure within a certain distance (around m) of a hotel, but once established, the concrete jungle blocks the propagation of the spatial pattern beyond that limit. this study uses binary logistic models and gis methods and tools to investigate the spatial pattern of urban tourism, with hong kong as an example. generally, the number of attractions in an area is negatively and significantly associated with the likelihood of establishing an upper-grade hotel. commercial land use type has the most significant and positive influence on the spatial distribution of upper-grade hotels. moreover, although tourists are inclined to choose hotels near traffic facilities, we find that traffic land type is not statistically significant. traffic accessibility is not an important consideration for establishing upper-grade hotels in highly convenient transport facilities areas such as hong kong. we also find that determinants vary over time. this study has both theoretical and practical implications. theoretically, it contributes to the literature of urban tourism by conducting a spatial and temporal analysis of urban tourism phenomena. it examines two aspects of urban hotel spatial structure. the first is the effect of the built environment on hotel location choice, which is the main focus of many previous hotel studies. the second, neglected by most previous research, is a temporal analysis of the relationship between hotels and the built environment after the hotels are built. the results reveal that after a certain period of operation, the spatial structure of hotels and their surrounding built environments are significantly changed within a certain radius. although this research is not able to directly examine how a hotel's operation influences the surrounding built environment, the significant temporal variation in the relationship between the dependent and independent variables such as the commercial land use may partly suggest that hotels influence the built environment in the surrounding area. this research also makes a methodological contribution by using logistic models for both the temporal and spatial dimensions. first, it uses a set of yearly models using time series data from to . these models are not only able to explore the relationship between the hotel level and built environment, but are also capable of examining temporal variation so that the changes in spatial structure can be investigated. to analyze the changes in the spatial patterns during the operation period, model is established. second, as the issue of spatial scale may greatly affect the result, different buffers are created so that the way in which spatial interaction varies with spatial scale can be understood. the study also has practical implications. the results suggest that in hong kong, traffic accessibility is not a significant variable, as hong kong is well known for its convenient public transport system, so developers need not consider this factor. furthermore, the establishment of hotels may affect the surrounding land use within a -km radius; for example, it may increase the area of commercial land. this in turn may attract more upper-grade hotels, which prefer to be located near commercial centers. in addition, due to limited land resources and the concrete jungle, some upperfloor shops could be regarded as potential tourism products, but these have not been fully developed. more promotion efforts should be dedicated to these shops to increase the diversity of tourism products and the attractiveness of hong kong as a shopping paradise. finally, several limitations of the study should be mentioned. first, the empirical model is developed under the assumption that there are already hotels at the selected locations, so it cannot analyze and predict the location choice of all types of hotels. second, owing to the limitations of the data sources, we cannot obtain historical data for hotels established before (e.g., the peninsula hong kong in ). if the historical data could be obtained, the results would be more convincing. finally, although it can be inferred that the changes in the spatial pattern of the area surrounding a hotel are related to the hotel's existence, the study is not able to quantify this relationship. future research efforts will be dedicated to developing a method for modeling the effect of hotels on the surrounding environment. some determinants of urban hotel location: the tourists' inclinations do implicit prices for hotels and second homes show differences in tourists' valuation for public attributes for each type of accommodation facility a gis-based analysis and prediction of parcel land-use change in a coastal tourism destination area urban tourism: an imbalance in attention monitoring land use changes in tourism centers with gis: uzungöl case study the application of geographical information systems (gis) in sustainable tourism planning: a review measuring efficiency in the hotel sector diverting the tourists: a spatial decision-support system for tourism planning on a developing island gis applications in tourism marketing: current uses, an experimental application and future prospects sustainable tourism infrastructure planning: a gissupported approach mapping landscape values and development preferences: a method for tourism and residential development planning economic impact of sporting events corporate social responsibility practices in four and five-star hotels: perspectives from hong kong visitors a gis-based spatial decision support system for tourists of great smoky mountains national park urban tourism research: developing an agenda gis applications in the planning and management of tourism. companion tour tourism, forest conversion, and land transformations in the angkor basin resort development impact on labor and land market assessing tourists' satisfaction with shopping in the hong kong special administrative region of a statistical review of hong kong hong kong tourism board, hong kong. hktb, c. hotel room occupancy report. hong kong tourism board visitor arrival statistics visitor arrival statistics. hong kong tourism board dimensions of hotel location in the kumasi metropolis relationship between spatial agglomeration and hotel prices. evidence from business and tourism consumers urban tourism: a key to urban regeneration understanding tourist movement patterns in a destination: a gis approach critical reflections on the economic impact assessment of a mega-event: the case of impacts of the olympic games as mega-events hospital variation and patient travel distances tourist development tourism today: a geographical analysis tourism development in paris: public intervention an integrative framework for urban tourism research use of gis-based models for integrating and developing marine fish cages within the tourism industry in tenerife (canary islands) a case study of environmental justice and federal tourism sites in southern appalachia: a gis application crumpet: creation of user-friendly mobile services personalised for tourism public goods in tourism municipalities: formal analysis, empirical evidence and implications for sustainable development the effects of beach characteristics and hotel location with respect to the beach on hotel prices managing tourism products and destinations embedding public good components: a hedonic approach structural social capital and hotel performance: is there a link the pure theory of public expenditure quality differentiation and conditional spatial price competition among hotels the geography of hotels in cities: an empirical validation of a forgotten model hotel location and tourist activity in cities research report: gis-oriented analysis of tourist time-space patterns to support sustainable tourism development point pattern analyses of accommodation in toronto model of urban tourism for small caribbean islands how do hotels choose their location? evidence from hotels in beijing theoretical, empirical, and operational models in hotel location research la localisation de l'industrie touristique: application de l'analyse de thunen-weber what determines multinational hotel groups' locational investment choice in china? an analysis of mainland chinese visitors' motivations to visit hong kong the work described in this article was supported by a grant from the research grants council of the hong kong special administrative region, china (project no. polyu / h), and the hong kong polytechnic university, china (project no. a-pl ). key: cord- -rrxgr authors: yau, yung title: collectivism and activism in housing management in hong kong date: - - journal: habitat int doi: . /j.habitatint. . . sha: doc_id: cord_uid: rrxgr management of apartment buildings is never straightforward because of the need for collective homeowner action. mancur olson suggests that a rational individual will not participate in collective action which provides no positive net benefit for him or her. based on this premise, it would seem that rationality drives homeowners to free-ride on others’ efforts and that, as a result, no collective action will take place. however, some homeowners do actively participate in housing management, and it is worthwhile to examine why some participate and others do not. building on the wide-ranging applications of the collective interest model (cim) in explaining political participation and environmental activism, this paper expands its relevance to the arena of housing management. the explanatory analysis which is based on the findings of a structured questionnaire survey in hong kong corroborates the central propositions of the cim and provides a theoretical account of housing management activism. in brief, housing management activism is a function of beliefs about personal and group efficacy, the value of the collective good, and the selective benefits and costs of participation. these findings have far-reaching implications for the formulation of government policies promoting homeowners’ active involvement in housing management in hong kong and other megacities. what makes the management of multi-owner housing different from that of single-owner housing is the social and economic interdependence of co-owners (bailey & robertson, ) . because of this particular feature, the proper management and maintenance of multi-owner housing necessitate collective action on the part of co-owners, which in turn depends very much on the latter's active participation. since the outcomes of proper building management and maintenance (e.g., better environmental cleanliness, building safety and security) are non-excludible, the free-rider problem is significant in the context of multi-owner housing management, as suggested by olson ( ) . olson's supposition helps to explain the prevailing mismanagement or disrepair of residential buildings in megacities such as hong kong, shanghai and taipei. although these high-density urban settings feature high-rise developments that allow the efficient use of communal facilities and services like mass transport systems (lynn, ; vlahov & galea, ) , they also pose higher health and safety risks to local communities due to high population density. the outbreak of severe acute respiratory syndrome (sars) in vividly demonstrated the consequences of the poor upkeep of private housing in high-density urban areas (hung, chan, law, chan, & wong, ) . the localised widespread transmission of sars in amoy gardens in hong kong and the wenhua community in taipei created a community health disaster in those cities (culpan & lin, ; hung et al., ) . although olson has a pessimistic view of homeowner participation in building care initiatives, not all buildings appear unmanaged. it is thus interesting to consider why some people choose to participate in housing management and others do not. the phenomenon of homeowner participation in housing management in hong kong provides an excellent laboratory for the study of such collective action behaviour. this paper draws on a cross-sectional household survey of homeowner activism in housing management in hong kong, and the collective interest model (cim) is used to explain homeowner behaviour. the cim posits that people choose to participate in a collective venture when the expected value of their participation exceeds the expected value of their non-participation. this paper is also a response to gaps within the body of academic literature on resident participation in housing management. although there are many previous studies in this field (e.g., leung, ; somerville & steele, ; wood, ) , most of them focus on the justifications for or benefits of engaging residents in housing management. only a few have addressed resident decision-making regarding participation. this paper first reviews the problem of housing mismanagement in hong kong from the perspective of collective action. next is a brief introduction to the cim, followed by the research methodology. a description of the data and the analysis results follow. the implications of the research findings will be discussed before the conclusion to the paper. the extent of the building problem in hong kong with a land area of around km , hong kong was populated by approximately million people or . million households at the end of (census and statistics . while there is an extensive public housing programme, over half of the population ( . %) lived in private permanent housing in hong kong at that time (hong kong housing authority, ) . as of , there are around , private buildings in hong kong, and over , of those buildings are at least years old. of these, some are at least years old (home affairs . in years' time, that number will increase to , (development bureau, ) . the home affairs database indicates that over , private buildings do not have any form of building management i.e., they are not managed by an owners' association or a property management company. it is a general belief that these old unmanaged buildings are most vulnerable to dereliction and dilapidation, jeopardising public health and safety of the community. the contemporary building problem in hong kong can be ascribed to the longstanding lack of building care culture in the city (housing, planning and lands bureau, ) . many homeowners in dilapidated buildings are indifferent to housing management affairs. they are reluctant to carry out safety inspections of their buildings and do not undertake the necessary renovations voluntarily. the natural consequence of building neglect is the unsatisfactory condition of the private building stock in hong kong, which is vividly evidenced by the large numbers of complaints about building dangers and accidents involving building structures in recent years. as shown in table , the number of complaints about building dangers increased at an average annual rate of . % over the thirteen-year period between and . more importantly, deaths and injuries were caused by building-related incidents from to (task force on building safety and preventive maintenance, ). in the last years, there was a new wave of building dangers created by falling building components like aluminium windows and concrete pieces (bowring, ; information services department, ; lo, ) . additionally, the proliferation of unauthorised building works (ubws) also poses safety hazards for building occupants and the general public lai & ho, ) . finally, many buildings in the city are at a high risk of fire due to poor fire safety management and inadequate upkeep of fire service installations. on january , a -years-old apartment building in tokwawan, hong kong suddenly collapsed, resulting in deaths (buildings department, b) . this event once again triggered public worry over building safety in hong kong. generally speaking, the building-related problems mentioned above were results of the lack of proper building maintenance (ho, ; wong, cheung, yau, ho, & chau, ) , which is in turn a consequence of building mismanagement. different attempts have been made to explain the mismanagement of private residential buildings in hong kong. however, the co-ownership arrangement that predominates in most of the multi-storey buildings in the area is commonly claimed to be the main underlying reason for the problem (e.g., walters, ; walters & kent, ; yip & forrest, ) . in hong kong, the vast majority of residents in the private housing sector live in multi-storey residential or apartment buildings that are commonly co-owned. owners of dwellings in these buildings do not actually 'own' their units exclusively (nield, ) . instead, they "each own an individual share in the whole of the building and the ground on which it is built, which they hold together as tenants in common" (nield, : p. ) . in other words, these individual owners have an exclusive right to use their own units, but at the same time, they are co-owners of the entire building structure, including common areas such as entrance lobbies, access corridors, staircases, lifts, lighting, service ducts and water pumps. under this ownership arrangement, the responsibility for managing the common areas and shared facilities in a building is thus jointly or collectively shouldered by all the coowners. in this regard, the co-ownership nature of multi-storey buildings has created social and financial connections between coowners (bailey & robertson, ) . the use, management and upkeep of a building's common areas thus require significant coordination and cooperation among co-owners and, more importantly, their active engagement in building care initiatives. consider, for example, efforts to monitor the performance of property management agents (pmas) in hong kong. the homeowners in a building must lodge complaints with the pma when the services provided by the pma are not sufficient. the motivation of the pma to improve its services is greater if there are many homeowners complaining about the poor services. if the situation does not change, the homeowners can form an owners' corporation for their building and terminate the pma's service contract. to form an owners' corporation, support from homeowners of at least % of the overall undivided shares is required. for service contract termination, % support is required. on these occasions, homeowner participation is needed to instigate collective action to monitor pma performance and penalise incompetence. although the use, management and upkeep of the common areas of multi-family housing are usually governed by a deed of mutual covenant (dmc), homeowners' participation in the management of this type of housing still remains voluntary in nature. proper building management and maintenance can offer homeowners a broad range of tangible and intangible benefits, but time and financial constraints and a lack of skills and knowledge are commonly identified as limitations on building care actions (kangwa & olubodun, ) . on this basis, homeowners may ignore building care rationally. as per the rational choice theory (homans, ; olson, ) , an individual can rationally ignore an issue if the cost of educating himself or herself about the issue which is sufficient to make an informed decision exceeds the expected benefits that he or she could obtain from that decision. to put it another way, given that the homeowners perceive that the benefits derived from their participation cannot cover the associated costs, it would be irrational for them to waste time and effort participating in housing management affairs. more importantly, there are homeowners who make some effort or hire a maid to clean the communal corridors in a building; then, other owners can benefit from the improvements in the environment without making a contribution themselves. the favourable outcome of any voluntary building care initiative is a non-exclusive public good. while it is theoretically possible to keep the 'free-riders' from enjoying the favourable outcome, the transaction costs incurred in monitoring and exclusion can be prohibitive. in this way, multi-family housing management exhibits the characteristics of a public good and is vulnerable to the freerider problem. rational homeowners, from a game-theory perspective, would be better off not to co-operate if they aimed to maximise their own pay-offs (bengtsson, ) . indeed, individuals in any group will attempt to reap the benefits of others' efforts if the group is working to provide a non-excludable and non-rival good (brunner, ; buchanan & tullock, ) . in his seminal work, olson ( ) suggests that non-action or non-participation is a rational choice if the personal benefits derived from taking action are perceived to be less valuable than the personal cost of making the effort. when homeowners must decide unilaterally whether or not to contribute to the provision of a public good, the dilemma of collection action predicts that most owners will behave opportunistically and free-ride on others' contributions (hovi & foss, ; lai & chan, ; walters & kent, ) . are there any solutions to the olsonian paradox of participation or the collective action dilemma? the literature identifies two main solutions. the first is to introduce selective incentives: benefits that participants can only derive from the activity irrespective of whether they manage to provide the public good (olson, ) . selective incentives, which can be in forms of rewards or punishments for individuals, are necessary to motivate homeowners to co-operate. however, bengtsson ( ) objects that selective incentives only lead to marginal solutions that are far from stable. the second solution is to relax the assumption that individuals view the importance of their own participation in the collective effort as negligible. in this approach, participation is explained in terms of collective interests as a combination of individual demands for the public good and perceptions of individual and group efficacy in the collective provision of the good. elster ( ) suggests that collective or community action is likely to occur when members of a 'group' are geographically close, have low turnover or membership, share a common interest and believe that they can succeed. under such conditions, homeowners may feel that participation offers genuine opportunities to influence collective decision-making and make gains. they are more willing to participate, and as a result, collective action is more likely to occur. in hong kong, not all homeowners are free-riders with regard to housing management. therefore, it is worth studying why some people participate and others do not. this study attempts to investigate homeowner participation in housing management in the city from the perspectives of selective incentives and collective interests. an empirical study is carried out in hong kong's private multi-family residential buildings using the cim, which was developed based on olson's ( ) logic of collective action. the cim is useful for investigating stakeholders' expectations regarding participation in collective action. the purpose of the cim is to "incorporate the demand for the public good into an individual's utility calculus without violating the logic of free-riding" (finkel, muller, & opp, : p. ). the model posits that an individual will participate in a collective endeavour if the expected value of participation for him or her exceeds that of non-participation (lubell, zahran, & vedlitz, ) . the calculation of the expected value depends on factors: ( ) the perceived value of the collective good provided by successful active action; ( ) the increase in the probability of success if the individual participates; ( ) the extent to which the actions of the group as a whole are likely to be successful; ( ) the individual's selective cots of participation; and ( ) the individual's selective benefits of participation. the cim predicts that participation hinges on selective incentives and a set of non-zero "collective interest variables" (finkel & muller, : p. ) . generally speaking, an individual's expected value of participation is judged based on the assessment of the total value of the public good (e.g., social welfare, environmental cleanliness and public safety), the influence of his or her participation on the collective outcome, and the selective benefits and costs of participation. since the cim is empirically testable, it has been widely used to explain individuals' participation in mass political activities (bäck, teorell, & westholm, ; finkel & muller, ; finkel et al., ) , institutional collaboration (weible, ) and environmental activism (lubell, ; lubell & vedlitz, ; lubell et al., ) . for example, finkel and muller ( ) find that variables drawn from a cim are important predictors of protest behaviour in germany. lubell ( ) , lubell and vedlitz ( ) and lubell et al. ( ) regard the cim a good candidate for a general theory of collective action behaviour. this is why the cim is applied to collective action in housing management in this study. when the cim is applied to homeowner participation in housing management, the expected value of participation or activism in housing management can be modelled mathematically as where ev(housing management activism) is the expected value of participation, p g is the probability that the group will be successful in providing the collective good (i.e., group efficacy), p i is the perceived marginal influence of the individual's contribution on the probability of success (i.e., personal influence), v is the perceived value of the collective good, c is the selective cost of participation, and b is the selective benefit obtainable from participation. as far as housing management is concerned, the collective good is a housing management outcome that is desirable for all homeowners e the creation of a hygienic, safe and pleasant living environment within the building. the terms in parentheses (v, p i and p g ) are collective interest variables. as indicated by lubell et al. ( ) , the incorporation of these collective interest variables into the cim reflects the fact that the successful provision of the public good depends on the efforts of the majority. in other words, the contribution of a single individual can only slightly increase the chance of providing a collective good successfully. this premise forms the basis for the logic of free-riding in the cim. this analysis uses data acquired through a face-to-face structured questionnaire survey administrated in the summer of . the questionnaire was designed to collect the information necessary for the empirical study. before the survey, the questionnaire was pretested and adjusted according to the tester feedback. faceto-face interviews and self-administered written questionnaires were used to maximise the number of respondents in the survey. a total of homeowners, accommodated in private multistorey residential buildings in the western district of hong kong were interviewed. the western district was chosen as the study area for two reasons. first, it is one of the oldest residential districts in hong kong since the british colonial reign in . secondly, there exists a wide variety of buildings ranging from old low-rise tenement blocks to high-rise apartment towers. this range of buildings creates a high degree of variation in buildings in terms of age, settings, and management regimes, which is essential to obtaining a diversified sample for analysis. the cim in equation ( ) is tested using ordinary least squares (ols) analysis. although a linear additive function form does not truly represent the multiplicative structure posited in the theoretical cim, it is used in this study. alternative strategies such as transformation into a logelog specification and the use of multiplicative scales have been proposed for estimating the multiplicative elements (e.g., finkel et al., ; whiteley, ) . however, lubell et al. ( ) object that these methods do not offer empirical qualities superior to those of linear additive specification. these alternative strategies are also flawed because of their sensitivity to measurement scales and rescaling. accordingly, equation ( ) is adapted as follows: to facilitate empirical testing, the variables in the adapted model are operationalised. table lists the major empirical variables used in the study to operationalise the concepts of the cim. as explained above, a rational individual will choose to participate in housing management if the expected value of his or her participation is positive. the individual will be more willing to participate if the expected value is greater. therefore, the expected value in equation ( ) per se determines the individual's participation level, part, which is used as the dependent variable for analysis in this study. a five-point scale ( ¼ very frequently; ¼ often; ¼ sometimes; ¼ seldom; ¼ never) is used to gauge homeowner levels of participation in five different aspects of housing management: namely, a) organising resident activities for the homeowners' associations; b) attending homeowners' meetings; c) speaking at homeowners' meetings; d) making comments and suggestions to the homeowners' association or the pma; and e) participating in the activities organised by the homeowners' association or the pma. the variable part averages the points received in these areas. group efficacy, p g , measures the chance that a group of homeowners will succeed in providing the collective good of housing management. it is estimated using factors, expected reciprocity and perceived group cohesion. expected reciprocity, exre, is measured using a -point likert scale (with ¼ strongly disagree and ¼ strongly agree) and indicates the extent to which an individual believes that other homeowners in his or her building will also participate in housing management. perceived group cohesion, cohe, is also measured using a five-point likert scale (with ¼ strongly disagree and ¼ strongly agree) and indicates the extent to which the individual believes that all co-owners in his or her building share the same values and can co-operate amicably and effectively to provide the collective good. these two variables are especially relevant in housing management. as previously mentioned, homeowner participation is essential for monitoring and maintaining the standard of housing management in a building. additionally, the assent of the majority of the co-owners in a building is required to kick off projects such as the formation of owners' corporations, the termination of a pma service contract or the execution of improvement projects. the activism of other homeowners is thus perceived as an important consideration for an individual homeowner considering participating in housing management. at the same time, if the homeowners are not united or do not form a cohesive unit, it is difficult for them to act collectively and work toward the same goal. in such a case, an individual may feel that no collective good will be produced in the absence of consonant views and actions by all (or the majority of) the homeowners. it is hence hypothesised that both exre and cohe increase housing management activism. personal efficacy, p i , refers to an individual homeowner's belief that his or her participation in housing management will increase the probability that the group will achieve the collective good. in many previous empirical studies (e.g., finkel et al., ; koontz, ; mohai, ) , self-perceived personal efficacy has been identified as a strong determinant of political participation and environmental activism. in the questionnaire for this study, the homeowners were asked to indicate their level of agreement or disagreement with the following statement using a five-point likert scale (with ¼ strongly disagree and ¼ strongly agree): 'your participation in housing management is likely to make a difference in the quality of your living place'. homeowners with greater perceived personal influence on the management outcome, infl, are predicted to be more active in housing management affairs. this study used an indirect approach to measure the perceived value of the collective good, v. the precise valuation of a collective good is difficult if not impossible (eagle, ; graves, ). again, the collective good achievable via housing management activism is a pleasant living environment for all homeowners in the building. this collective outcome will have a greater perceived value for a homeowner if the latter feels that existing conditions differ significantly from what would be expected. thus, in this sense, v represents the individual's level of dissatisfaction with the existing management of the building. homeowner discontent, disc, including six aspects of housing management outcomes (namely, environmental hygiene, fire safety, upkeep of services, structural safety, security, and control of neighbourhood problems) are assessed in the questionnaire using a five-point scale (with ¼ very satisfied and ¼ very dissatisfied). disc averages the answers to the six questions about homeowner dissatisfaction. a positive relationship between the levels of participation and discontent is hypothesised. an individual's ability to pay the selective costs of participation, c, is largely determined by the availability of the money, time, knowledge and skills necessary for his or her effective participation (brady, verba, & schlozman, ) . based on this concept and the work of lubell ( ) and lubell et al. ( ) , c is reflected by a range of demographic variables in the operationalised model. a total of four demographic variables are included in this study. male is the dummy variable, which equals for males and zero if otherwise. age is a six-category scale for homeowner age ( ¼ e years old; ¼ e years old; ¼ e years old; ¼ e years old; ¼ e years old; ¼ years old or above). edu is a six-category scale for the homeowner's highest education level attained ( ¼ primary school or below; ¼ lower secondary school; ¼ upper secondary school; ¼ matriculation; ¼ sub-degree post-secondary education; ¼ degree or above). hinc is a six-category measure of average monthly homeowner household income ( ¼ below hk$ , ; ¼ hk$ , e , ; ¼ hk$ , e , ; ¼ hk$ , e , ; ¼ hk $ , e , ; ¼ hk$ , or above). two variables are used to estimate selective benefits, b. the first variable is the value of housing management, mval, and indicates the importance of the collective good to the individual's quality of life. each individual was asked to answer the following statement using a -point likert scale (with ¼ strongly disagree and ¼ strongly agree): "better housing management can improve your quality of life". the idea was that if one perceived housing management as being more valuable, a higher level of housing management activism would be the outcome. the second variable is the individual's enjoyment of life as a resident in the building, life, which constitutes a kind of expressive incentive according to the categorisation by bäck et al. ( ) . expressive incentives are rewards that an individual can receive only when he or she participates. the variable is assessed using a -point scale (with ¼ dislike very much and ¼ like very much). after operationalisation, the model becomes where a i (for i ¼ , , ,., ) are coefficients to be estimated and where is the stochastic term. to facilitate the interpretation of the results, all attitude measures, including the dependant variables, are linearly rescaled to the continuous [ , ] range before model estimation. the demographic characteristics of the respondents are summarised in table . most of the respondents represent the low-or medium-income group. the average age of the buildings in question was years at that time. each building has dwelling units on average, and the number of storeys ranges from four to . buildings ( . %) have owner corporations. among the nine buildings without owner corporations, two have mutual aid committees organised by the owners and tenants. table presents the mean responses for these variables before rescaling. the ols analysis results are presented in table . the adjusted r-squared is . , which is quite high compared to the results of other empirical studies of the cim. the analysis results confirm several important aspects of the cim. all collective interest variables are found to be positive and statistically significant at the % level, indicating that expected reciprocity, perceived levels of group cohesion and personal influence on outcome and discontent level all enter into the decision calculus of the average homeowner. of the four collective interest variables, discontent level (disc) is the strongest predictor of part, though its estimated coefficient is not statistically different from that of infl at the % level. homeowners participate more if they have higher levels of discontent with the current housing management outcome. these results confirm yau's ( ) findings that the approach of homeowners to building care in hong kong is predominantly reactive. these residents are not active in housing management affairs unless they can no longer tolerate the problems occurring in their buildings. perceived outcome influence, infl, is found to be nearly as important as discontent level. as implied by the results, even when the perceived collective benefits of housing management activism are high, homeowner participation may be unlikely because homeowners see themselves as incapable of changing the collective outcomes. the positive sign of the coefficient of exre suggests that homeowners who believe that their neighbours will reciprocate expect more benefits than costs from housing management activism, whereas this is not true of those who do not believe that their neighbours will reciprocate. moreover, part increases with cohe, indicating that homeowners who perceive stronger cohesion among the co-owners in their buildings are more active participants. both variables gauging the collective efficacy of the 'homeowners groups' have an influence on individual homeowner decisions regarding housing management activism. these results confirm weible's ( ) proposition that a group's collective efficacy shapes individual members' expectations, which in turn determines their participation (and non-participation). selective cost measures how the typical demographic variables considered in other studies fit into the cim for housing management activism. although gender has no significant effect on housing participation level, better-educated and older homeowners engage more actively in housing management affairs. interestingly, the estimated coefficient of hinc is negative, but it is not significant even at the % level. that means that income shows no effect on housing management activism. this is probably because the higher opportunity costs of participation for high-income offset the benefits. the analysis results indicate that both selective benefit variables are positively correlated with the level of housing management activism. the estimated coefficient of the variable mval is significant at the % level, and the coefficient of the variable life is significant at the % level. nevertheless, there is no statistical difference between the magnitudes of the two coefficients at the % level, indicating that the two variables are of nearly equal importance. as one can infer from these results, homeowners who are more active in housing management affairs tend to value the collective good of better housing management higher. at the same time, expressive benefit is a strong motivator for housing management activism. there are several important points that emerge from these results. first, as far as the sustainable management of the housing stock is concerned, routine maintenance and timely rehabilitation are more preferable to demolition and rebuilding because the former methods are more economical, environmentally friendly and socially favourable (jones & clements-croome, ; yau & chan, ) . however, the empirical findings of this study suggest that although self-perceived personal influence affects the likelihood of housing management activism, homeowners will participate only if they are dissatisfied with housing management outcomes. these findings reflect the reactive nature of these homeowners to housing problems: as long as they can tolerate existing housing management outcomes, they continue letting others do the work for them. this free-riding dogma essentially creates a deadlock in building care in hong kong. secondly, in decisions regarding participation, perceived group efficacy in achieving a desirable outcome is important. a homeowner will not participate in housing management if he or she regards other homeowners as free-riders. in addition, homeowner participation will be unlikely if the individual in question thinks that the group cannot work effectively to achieve better housing management for the building. in other words, participation decisions depend very much on the individual homeowner's perceptions of his or her neighbours. even when a person thinks that he or she is capable of making a change, his or her participation may be in vain if other homeowners do not participate or cannot work well with each other. this observation actually echoes the views of bengtsson ( bengtsson ( , who comments on the resident dynamics in housing management. predictions regarding others' behaviour determine homeowner actions. last but not least, despite the insignificant coefficients of the variables male and hinc, the analysis results generally support the expectations of the cim. the expected value of participation not only depends on selective interests and the cost of participation, which are private but also rests on the perceived value of the collective good to be produced and the chances of success in providing the good. as deduced from the analysis results, an individual homeowner will choose to participate in housing management under the following conditions: ( ) if the homeowner perceives that his or her selective cost of participation exceeds the selective benefit and if the expected collective interest is greater than the negative net selective benefit; or ( ) if there is zero expected collective interest and the net selective benefit perceived by the homeowner is positive. on this basis, we can offer insight into how the housing mismanagement problem in hong kong might be resolved. given that the selective costs of participation are relatively fixed, we can boost the expected value of housing management activism by increasing either the selective benefits of participation or the collective interests. in the first approach, institutional arrangements or economic incentives can play a role. currently, if the majority of homeowners at an owners' meeting come to a consensus (e.g., a decision to upgrade the elevator system), the minority may not participate. the owners' corporation can only bring the case to court to bring the uncooperative owners in line. since this method is often too costly and time-consuming, it is not used very often. the resolution in question will then be discarded or simply put on hold. this frequently occurs and is a major reason why plans for improving building conditions or management are suspended. legislation can be developed to punish uncooperative owners or those who do not participate even if the majority of homeowners in a building collectively agreed. this tactic increases the costs of free-riding, which indirectly increases the selective benefits for those who participate in housing management. the government can also educate homeowners about the economic benefits of better housing management (e.g., higher property rental values and shorter downtime for services) and economic losses that can arise from housing mismanagement (e.g., higher medical costs and huge damages payable to the victims of building-related accidents). however, it is sometimes difficult for the average homeowner to visualise the association between housing management performance and property value because with the exception of physical conditions, the various performance aspects of housing management (e.g., financial management and dispute resolution) are not easily observable by outsiders. therefore, assessment schemes for benchmarking the overall performance of housing management should be devised and implemented for all apartment buildings in hong kong. this step would make additional information available to the market and create a 'league of value' in the form of higher-scored properties that should command a higher rent or value. with a view toward the potential economic benefits, homeowners may perceive greater value in housing management and may be more likely to participate actively in housing management. another approach would be to enhance collective interests by reinforcing social bonding among homeowners. if a strong sense of community and cohesion exists among neighbours within a building, homeowners may hold very similar values regarding housing management. as a result, each of them will expect a greater degree of reciprocity from the other and a close working relationship will be there to keep their building a pleasant place to live. the government and owners' associations can help amplify the collective or group efficacy in achieving the collective good by fostering long-term partnerships among homeowners. more supports or subsidies should be offered by the government and owners' associations to organise social gatherings and activities which can bring homeowners together. mechanisms like mediation should also be put in place to resolve disputes or conflicts between homeowners in an amicable and non-destructive manner. otherwise, a long-term relationship cannot be ensured. a high-density urban setting is economically efficient because it maximises the use of communal facilities and services. on the other hand, it may potentially create health and safety risks for the community because there is a strong link between the built environment and people's state of health. another drawback of high-density living environments is the predominance of high-rise multi-family buildings, the management of which can be particularly difficult. co-ownership arrangements in these buildings create a need for collective action among homeowners in order to achieve effective housing management. nevertheless, because its outcome is a public good, housing management is always subject to the freeriding problem. in investigating the dilemma of collective action among homeowners, this article uses the cim to investigate the benefit-cost expectations associated with participation in the management of apartment buildings in hong kong. based on the analysis results, key elements of the cim e the perceived value of housing management outcomes, personal efficacy, group efficacy, selective costs and selective benefits e were found to be directly and positively related to the level of housing management activism. this study establishes the relevance of the cim as an explanatory framework for homeowner participation in housing management. the findings of this study can have a positive impact on housing management policy-making in hong kong and can also offer insight into the sustainable management of the housing stock in other megacities. additionally, this study should stimulate more research on the dilemma of collective action for homeowners. it may be very interesting to further explore whether homeowner activism is sensitive to the existence of owners' associations and the involvement of pmas. it would also be worth studying how government policies or schemes adjust the decision calculus of homeowners. moreover, given the rise of urban activism (e.g., in fights for public open spaces or heritage conservation) in many asian cities in recent years, the applications of the cim might include future analyses of the behaviour associated with community participation. explaining modes of participation: an evaluation of alternative theoretical models, paper presented at the european consortium for political research joint sessions of workshops management of flats in multiple ownership: learning from other countries tenants' dilemma: on collective action in housing solving the tenants' dilemma: collective action and norms of co-operation in housing. housing beyond ses: a resource of political participation free riders or easy riders? an examination of the voluntary provision of public radio the calculus of consent monthly digest monthly digest monthly digest report on the collapse of the building at j ma tau wai road, to kwa wan hong kong in figures: edition. hong kong: government logistics department cover story: in the wake of the health crisis building safety, discussion paper no. cb( ) / - ( ) for the panel on development environmental amenities, private property, and public policy logic and society rational choice and the dynamics of political action: evaluating alternative models with panel data personal influence, collective rationality, and rational choice, and democratic values in the former soviet union a note on the valuation of collective goods: overlooked input market free riding for non-individually incrementable goods maintenance management of aging buildings in hong kong a survey of the health and safety conditions of apartment buildings in hong kong evaluating unauthorized appendages in private apartment buildings social behaviour: its elementary forms database of private buildings in hong kong housing in figures building management and maintenance: consultation paper. hong kong: government logistics department the collective action problem and some of its solutions industrial experience and research into the causes of sars virus transmission in a high-rise residential housing estate in hong kong towards a sustainable urban environment an investigation into home owner maintenance awareness, management and skill-knowledge enhancing attributes why participate? the collective interest model and citizen participation in watershed groups the formation of owners' corporations in hong kong's private housing estates unauthorized structures in high-rise high-density environment resident participation: a community-building strategy in lowincome neighbourhoods windows plunge in reminder of deadly threat. south china morning post environmental activism as collective action collective action, environmental activism, and air quality policy collective action and citizen responses to global warming megacities sweet dreams or environmental nightmares? environmental science and technology public concern and elite involvement in environmental conservation issues legal framework of deeds of mutual covenant the logic of collective action: public goods and the theory of groups making sense of tenant participation accidents related to building safety since urbanization, urbanicity and health transaction costs of collective action in hong kong high rise real estate institutional economics and property strata title e a survey and case study a collective interest model approach to explain the benefitcost expectations of participating in a collaborative institution rational choice and political participation: evaluating the debate resident participation, social cohesion and sustainability in neighbourhood renewal: developing best practice models are our residential buildings healthy and safe? a survey in hong kong engaging homeowners in building care in hong kong: drivers and barriers to rehabilitate or redevelop? a study of the decision criteria for urban regeneration projects property owning democracies? homeowner corporations in hong kong the work described in this paper was supported by the start-up grant for new staff from city university of hong kong (project no. ). the author would also like to express gratitude to the student assistants at city university of hong kong for their assistance with the data collection process. key: cord- -ai hz uq authors: hung, ivan fan-ngai; cheng, vincent chi-chung; li, xin; tam, anthony raymond; hung, derek ling-lung; chiu, kelvin hei-yeung; yip, cyril chik-yan; cai, jian-piao; ho, deborah tip-yin; wong, shuk-ching; leung, sally sau-man; chu, man-yee; tang, milky oi-yan; chen, jonathan hon-kwan; poon, rosana wing-shan; fung, agnes yim-fong; zhang, ricky ruiqi; yan, erica yuen-wing; chen, lin-lei; choi, charlotte yee-ki; leung, kit-hang; chung, tom wai-hin; lam, sonia hiu-yin; lam, tina poy-wing; chan, jasper fuk-woo; chan, kwok-hung; wu, tak-chiu; ho, pak-leung; chan, johnny wai-man; lau, chak-sing; to, kelvin kai-wang; yuen, kwok-yung title: sars-cov- shedding and seroconversion among passengers quarantined after disembarking a cruise ship: a case series date: - - journal: lancet infect dis doi: . /s - ( ) - sha: doc_id: cord_uid: ai hz uq background: a cruise ship is a closed-off environment that simulates the basic functioning of a city in terms of living conditions and interpersonal interactions. thus, the diamond princess cruise ship, which was quarantined because of an onboard outbreak of covid- in february, , provides an opportunity to define the shedding pattern of severe acute respiratory syndrome coronavirus (sars-cov- ) and patient antibody responses before and after the onset of symptoms. methods: we recruited adult (≥ years) passengers from hong kong who had been on board the diamond princess cruise ship docked in yokohama, japan in february, . all participants had been found to be negative for sars-cov- by rt-pcr days before disembarking and were transferred to further quarantine in a public estate in hong kong, where they were recruited. participants were prospectively screened by quantitative rt-pcr (rt-qpcr) of nasopharyngeal and throat swabs, and serum igg and igm against internal nucleoprotein and the surface spike receptor-binding protein (rbd) of sars-cov- at baseline (upon entering quarantine) and on days , , and of quarantine. findings: on feb , , adults were recruited, of whom nine ( %; % ci – ) were positive for sars-cov- by rt-qpcr or serology and were hospitalised. of these nine patients, nasopharyngeal swab rt-qpcr was positive in eight patients ( %; – ) at baseline. all nine patients were positive for anti-rbd igg by day . eight ( %; – ) were simultaneously positive for nasopharyngeal swab rt-pcr and anti-rbd igg. one patient who was positive for anti-rbd igg and had a negative viral load had multifocal peripheral ground-glass changes on high-resolution ct that were typical of covid- . five patients ( %; – ) with ground-glass changes on high-resolution ct were found to have higher anti-nucleoprotein-igg od values on day and and anti-rbd igg od value on day than patients without ground-glass changes. six ( %; – ) patients remained asymptomatic throughout the -day quarantine period. interpretation: patients with covid- can develop asymptomatic lung infection with viral shedding and those with evidence of pneumonia on imaging tend to have an increased antibody response. positive igg or igm confirmed infection of covid- in both symptomatic and asymptomatic patients. a combination of rt-pcr and serology should be implemented for case finding and contact tracing to facilitate early diagnosis, prompt isolation, and treatment. funding: shaw foundation hong kong; sanming-project of medicine (shenzhen); high level-hospital program (guangdong health commission). a modern cruise ship is like a travelling city, with a common food and water supply, shared sanitation and airconditioning systems, and a large population confined together. the individuals are often from a middle-toupper social class, with different cultures, immunisation backgrounds, and health statuses. the proximity of passen gers and crew members in a semi-enclosed environ ment, with interactions in the dining halls, recreational rooms, spas, and pools, creates a unique environment for the person-to-person transmission of microbes. contamination of commonly shared and frequently touched surfaces, food, or water supply or sanitation systems can occur and can cause considerable morbidity and mortality. cruise passengers tend to be older people, with the - -year-old group accounting for the majority, who are more likely to have underlying chronic medical comorbidities and thus be more susceptible to infection and associated complications than the general population. common reported out breaks on cruise ships have included respiratory infections with influenza a h n and h n , legionnaires' disease, and acute gastroenteritis due to norovirus. , [ ] [ ] [ ] [ ] since the emergence of severe acute respiratory syndrome coronavirus (sars-cov- ) in december, , the virus has caused a pandemic affecting more than · million people, with more than deaths in countries. [ ] [ ] [ ] [ ] on jan , , an -year-old man from hong kong boarded the diamond princess cruise ship in yokohama, japan, and disembarked in hong kong on jan , (figure ). on feb , , he was hospitalised with fever and tested positive for sars-cov- . the cruise continued to vietnam and taiwan, then returned to yokohama, at which time ten passengers were diagnosed with coronavirus disease (covid- ), and a -day quarantine order was imposed for all passengers and crew on board. between feb , and feb , , the japanese health ministry tested all passengers by throat swab rt-pcr; individuals who tested positive were isolated in local hospitals. individuals who tested negative were kept on board confined to their cabins and were only allowed out of the cabin for h per day to exercise. the ship remained docked in the port of yokohama. by feb , countries were allowed to air-evacuate citizens back to their home nations. therefore, the hong kong government chartered two flights on feb and feb to transfer passengers who had tested negative to hong kong for a further days of quarantine in a newly completed public estate. as of may , , ( %) of the passengers and crew had been infected with sars-cov- , and deaths had occurred among those with confirmed infection. we investigated the sequential sars-cov- shedding and the specific antibody response in this cohort of passengers quarantined in hong kong. hong kong citizens were air-evacuated from the diamond princess cruise ship on feb and feb , , and entered quarantine in the chun yeung estate, a newly built and vacant public estate in hong kong, on feb . each unit had a bathroom and kitchen and housed one to two people. during the -day quarantine period, they were placed in complete isolation. only health-care workers from the hong kong department of health would visit daily to do health checks and to deliver meals. family visits and contact with the general public were not allowed and individuals were asked to handle their own laundry. with approval by the department of health, we visited and collected samples from the individuals together with the aforementioned health workers. all adult passengers aged years and older were screened and given the choice to join the study. there were no exclusion criteria. all participants provided written informed consent and could withdraw from the study at any point. the institutional review board of the university of hong kong and hospital authority approved this study. participants were screened by quantitative rt-pcr (rt-qpcr) for sars-cov- in nasopharyngeal, throat, and rectal swabs at baseline (feb , ), day , day , and day , and tested for serum igg and igm against both internal nucleoprotein and the surface spike receptorbinding protein (rbd) of sars-cov- , at baseline, day , day , and day . the following participant data were entered into a database: name, hong kong personal identification number, age, sex, medical history by completion of a questionnaire, presenting symptoms and signs, and laboratory, radiological, virological, and serological evidence before this study we searched pubmed on march , , with no date restrictions, for articles in english, using the terms "covid- ", "coronavirus", "antibody", "viral load", "cruise ship", "quarantine", "shedding", and "seroconversion". our search did not identify any reports on the prospective follow-up of severe acute respiratory syndrome coronavirus (sars-cov- ) viral shedding and seroconversion in a cruise ship setting. we identified one case report on the clinical presentation of two individuals on the diamond princess cruise ship, and an article estimating the effectiveness of public health measures on controlling the covid- epidemic potential on a cruise ship. to our knowledge, this is the first cruise ship study of the clinical evolution and seroconversion from coronavirus disease (covid- ) from last possible exposure to the pathogen to the end of the suspected incubation period. the study showed that asymptomatic individuals might seroconvert while carrying a high viral load and continue to shed the virus. patients who had viral pneumonitis detected by high-resolution ct tended to have a higher antibody response. high-resolution ct also helped to establish a clinical diagnosis and detect cases of asymptomatic lung infection. asymptomatic covid- infection with continuous viral shedding makes infection control difficult. therefore, a combination of rt-pcr and serology should be implemented for case finding and contact tracing in a community outbreak of covid- to facilitate early diagnosis, prompt isolation, and treatment. high-resolution ct could also help to detect cases of asymptomatic infection. findings. participants who developed symptoms or who were found to have virological or serological evidence of sars-cov- infection at the time of screening were admitted to the queen mary hospital or the queen elizabeth hospital in hong kong for further investigation and treatment. all hospitalised participants under went chest radiograph and high-resolution ct examination. nucleic acid extraction and rt-qpcr were done as previously reported. enzyme immunoassays for nucleoprotein and rbd and optical density (od) cutoff values at nm and nm were established as previously described. the cutoff value for positivity was based on the mean value plus sds of the negative control, using archived serum specimens collected in from anonymous individuals without sars-cov- infection. descriptive statistics are presented. findings of the participants who tested positive for sars-cov- are presented as a case series. all data were analysed with spss (version . ). the funders of the study had no role in study design, data collection, data analysis, data interpretation, or writing of the report. the corresponding author had full access to all the data in the study and had final responsibility for the decision to submit for publication. of passengers and crew members on board the diamond princess cruise ship, passengers ( %) were from hong kong (appendix). the passengers returned to yokohama on feb , , and were quarantined onboard for a further days (figure ). by feb , , passengers from hong kong were hospitalised in japan after testing positive for sars-cov- by throat swab rt-pcr, of whom two individuals died from complications of the infection (appendix). passengers from hong kong who tested negative were allowed to disembark, of whom decided to stay in japan and passengers ( adults and three children) returned to hong kong for further quarantine. the three children were excluded from the study because their clinical data were not available for assessment. ten passengers declined to join the study and remained well until discharge. thus, adult participants were enrolled. baseline charac teristics of participants who tested positive (n= ) and negative (n= ) for sars-cov- were well matched (table ) . nine ( %; % ci - ) of participants were found to have evidence of sars-cov- infection and were hospitalised. these nine individuals were not related to each other; they boarded the ship in hong kong on jan , , when the index passenger had already disembarked and therefore had no contact with him (figure ). at the last onboard covid- testing by throat swab on feb , , all nine individuals tested negative. both parents and the grandfather of patient had tested positive for sars-cov- at the initial governmental screen in japan. they were subsequently discharged from hospital in japan after testing negative, and they returned to hong kong in march, . we have ordered the nine patients who tested positive for sars-cov- in the probable order of infection, according to their viral load and serological profile ( patients vs none). three ( %; % ci - ) of the nine patients with sars-cov- were men, and six ( %; - ) had underlying diseases, including hypertension, ischaemic heart disease, diabetes, hyperlipidaemia, old pulmonary tuberculosis, and non-toxic multinodular goitre. the median age was years (iqr - ). the median (iqr) laboratory findings were: haemoglobin · g/dl ( · - · ), white cell count · × ⁹ per l ( · - · ), neutrophil count · × ⁹ per l ( · - · ), lymphocyte positive viral load could precede the onset of symptoms, as evidenced by patient . the median nasopharyngeal viral load at baseline was · log copies per ml (iqr · - · ), on day was · log copies per ml ( · - · ), on day was · log copies per ml ( · - · ), and on day was · log copies per ml ( · - · ). three patients ( %; % ci - ) were found to be positive for sars-cov- on throat swab rt-qpcr (table ). the median throat swab viral load at baseline was · log copies per ml (iqr · - · ) and at day was · log copies per ml ( · - · ). the viral loads in the throat swabs were lower than those in the nasopharyngeal swabs at the same timepoints. rectal swab viral load was negative in all nine patients. the nasopharyngeal sars-cov- rt-qpcr median viral load was higher in symptomatic patients than in asymptomatic patients ( · log copies per ml vs · log copies per ml). chest radiographs showed changes consistent with interstitial pneumonia in four patients ( %; % ci - ), with right lower lobe changes in patient , right middle lobe changes in patient , left lower lobe changes in patient , and right lower lobe changes in patient (table , figure ). chest radiographs were normal in four patients ( %; % ci - ) and patient had old granuloma from previous pulmonary tuberculosis. highresolution ct (table , figure ) showed ground-glass changes typical of covid- in five patients ( %; % ci - ): patients and had right lower lobe ground-glass changes, patient had right upper and lower lobe changes, patient had right middle lobe changes, and patient had left upper and lower lobe changes. patients , , and had normal chest radiograph and ct results, but tested positive on nasopharyngeal swab rt-pcr (table ) . patients and were asymp tomatic, whereas patient developed fever and rhinorrhoea on day - . three patients (patients , , and ) had pulmonary ct changes but were asymptomatic. all nine patients were found to be positive for anti-rbd igg ( % seroconversion) on days and (table ) . to our knowledge, this is the first study that investigates the real-time progression of a group of individuals who were initially negative for sars-cov- on rt-pcr after exposure to an outbreak of covid- on a cruise ship. nine individuals later tested positive on rt-pcr from nasopharyngeal swab, had high-resolution ct changes, or showed seroconversion, and were thus found to be infected with sars-cov- . despite the positive clinical findings, six of the nine patients remained asymptomatic throughout the -day quarantine after leaving the ship (ratio of symptomatic to asymptomatic patients : ). if the cruise ship epidemic is a microcosm of the community outbreak scenario, then individuals with or without pneumonia could carry the virus for a long period but remain asymptomatic. , asymptomatic patients with few or no comorbidities could spread the disease, whereas symptomatic patients represent only a small, but visible, proportion of total cases. this finding is particularly important in densely populated cities like hong kong, with an average living space of · m² per person, equivalent to half a parking space. viral shedding from asymptomatic individuals could be transmitting the virus to others, making it difficult to identify and isolate index patients by contact-tracing for early quarantine. trans mission from asymptomatic individuals could explain in part the rapid increases in numbers of new cases in high-incidence countries such as the usa, russia, the uk, brazil, and european nations. sars-cov- could be spreading via respiratory droplets or through direct and indirect contact via the respiratory and gastrointestinal tracts. , considering that most outbreaks on cruise ships are of respiratory and gastrointestinal infections, the risk of infection and associated morbidity and mortality in passengers increases with longer duration of travel and colder weather. , the period of exposure on the diamond princess cruise ship was weeks, during which the passengers were unable to disembark, which is consistent with the high number of passengers (n= ) who contracted the infection. the situation was likely to have been made worse by infected but asymptomatic crew members who continued to work unprotected, but who could have been shedding the virus. a recent modelling study estimated that the initial basic reproduction number (r ) of the outbreak on the diamond princess cruise ship was · , before any infection control measures had been implemented and while the passengers were a completely naive group. the r then decreased to · after the quarantine and transfer interventions were initiated (feb - , ). this estimation of r was lower than that of · ( % ci · - · ) that was suggested at the beginning of the outbreak in wuhan, although a higher r of more than has also been reported. an r of · for covid- would be similar to that of sars and influenza. nevertheless, evacuation of all passengers and crews early on in the outbreak would probably have prevented more infections, as suggested by the current findings. because the screening test was done between early february and mid-february, before the air evacuation, we assumed that passengers could have acquired and been incubating the infection shortly before the test, and therefore tested negative, or they could have acquired the infection after the test. based on this assumption, we screened passengers by serial virological, serological, and radiological methods. our findings show a dynamic clinical presentation of sars-cov- . of the three diagnostic methods we used, the immunoassay for igg and nasopharyngeal swab rt-qpcr were the most sensitive. throat swab rt-qpcr was less sensitive; it identified only the two patients who consistently had the highest viral load in nasopharyngeal swab rt-qpcr and did not identify the other six patients identified by nasopharyngeal swab rt-qpcr. the apparent low sensitivity of throat swab rt-qpcr might also account for the negative screening test done on board the ship by the japanese health ministry. the three patients who were febrile felt transiently unwell, with concomitant symptoms of malaise, unproductive cough, and rhinorrhoea. the higher baseline nasopharyngeal swab viral load in symptomatic than asymptomatic patients in this study could be explained by the difference in time and degree of exposure to the virus, and might not be related to the symptoms. nevertheless, the per sistent nasopharyngeal viral load in asymptomatic patients is a major concern for infection control. rectal swabs were negative in all nine patients, which was expected because none of the patients presented with diarrhoea. important initial laboratory markers, including lymphocyte count, c-reactive protein, and lactate dehydrogenase, remained normal in these asym ptomatic patients. seroconversion occurred in all nine patients and it was the only diagnostic marker that was positive for one patient in this cohort who had high-resolution ct changes characteristic of a recent sars-cov- infection. for those patients who might have acquired the infection earliest and only shortly before the screening test, they might have seroconverted with a high igg titre and remained asymptomatic with a negative rt-qpcr, with high-resolution ct radiological evidence of sars-cov- pneumonitis with ground-glass changes. the immunological response could be explained by the lower respiratory tract infection consistent with pneumonia. similar to influenza viral infection, patients with severe disease and pneumonia had the highest antibody response. this finding could be related to the more severe viral infection resulting in a stronger induction of the host's adaptive immunity mediated by b and t cells. because sars-cov- and sars-cov have % amino acid homology for nucleoprotein and % amino acid homology for rbd, serum from patients with sars-cov might cross-react with our sars-cov- immunoassay, as shown by another group. however, the cross-reactivity between sars-cov- and other human coronaviruses is expected to be lower, because the amino acid homology with nucleoprotein is less than %. based on our previous study, the sensitivity of the serology assay was % for anti-nucleoprotein igg, % for anti-nucleoprotein igm, % for anti-rbd igg, and % for anti-rbd igm. as stated in the methods, the cutoff was based on a pre-pandemic general population cohort of individuals without sars-cov- infection. therefore, we expected that % would be outliers. the clinical presentation of the nine patients in this cohort ranged from mild to severe. among the mild cases, patients could remain asymptomatic (patients , , and ) or symptomatic (patient ), with no lower respiratory tract involvement, as suggested by normal chest radiograph and high-resolution ct. their antinucleoprotein and anti-rbd igg levels were low. patients with moderate infection had lower respiratory tract involvement, as suggested by the ground glass changes on high-resolution ct. nevertheless, they could still remain asymptomatic (patients , , and ) or become symptomatic (patient ). these patients had higher antinucleoprotein and anti-rbd igg than patients with mild disease. patient , who acquired the infection more recently, developed symptoms upon hospitalisation. the infection was more severe, involving the lower respiratory tract, with ground glass changes on high-resolution ct. seroconversion took place during the observation period, with anti-nucleoprotein and anti-rbd igg still increasing at the end of the observation period. overall, anti-rbd igg was the most sensitive serology marker, although the anti-nucleoprotein igg response was stronger. the difference in anti-rbd igg and antinucleoprotein igg could be related to the severity of the viral infection, in which anti-rbd igg was positive even in patients with upper respiratory tract infection, but at low od values. indeed, serology provides a feasible strategy to track sars-cov- infections. we also investigated changes in igm/igg ratio for anti-nucleoprotein and anti-rbd and did not identify any trends that might reflect the timing of infection. similar to findings from one of the largest case series from china, high-resolution ct provided a reasonable diagnostic tool, especially in asymptomatic patients. in this cohort, it was able to detect lung ground-glass opacities in five of nine patients, including the three patients with asymptomatic lung infection. similar to other studies, right-side changes were more common. individuals with more severe radiological changes tended to have higher nasopharyngeal viral load. high-resolution ct could also detect an rt-qpcr-negative asymptomatic patient (patient ) who had high igg and igm titres, suggestive of a recent infection. nevertheless, individuals who develop only an upper respiratory tract infection could still have a normal high-resolution ct. chest radiograph detected radiological changes in only four patients. this study has several limitations. we did not have access to the data of patients who were hospitalised in japan. we also did not have the cabin number and location of the participants when they were on board the ship, which could have provided some insight into how the infection was transmitted. ten passengers did not give consent to participate in the study, and therefore we did not have their virological or serological data. lastly, the study period was limited by the quarantine period and we could not follow up the participants beyond days. the participants could have become rt-pcrpositive or antibody-positive after the quarantine period. the cruise ship setting provided an unusual opportunity to study the viral shedding and seroconversion of sars-cov- , mimicking the start of a community outbreak. passengers who are exposed to the virus might seroconvert while remaining asymptomatic with a high viral load, and they could continue to shed the virus. highresolution ct also helped to establish a clinical diagnosis and to detect cases of asymptomatic lung infection. a combination of rt-qpcr and serology should be done to screen for community outbreaks and effectively perform contact tracing. we declare no competing interests. infections on cruise ships how old is the average cruise passenger? outbreaks of pandemic (h n ) and seasonal influenza a (h n ) on cruise ship a large outbreak of influenza a and b on a cruise ship causing widespread morbidity molecular characterization of influenza b virus outbreak on a cruise ship in brazil respiratory infections and gastrointestinal illness on a cruise ship: a three-year prospective study a familial cluster of pneumonia associated with the novel coronavirus indicating person-toperson transmission: a study of a family cluster clinical features of patients infected with novel coronavirus in wuhan, china clinical characteristics of coronavirus disease in china who. coronavirus disease (covid- ) situation report- covid- outbreak on the diamond princess cruise ship: estimating the epidemic potential and effectiveness of public health countermeasures about new coronavirus infection improved molecular diagnosis of covid- by the novel, highly sensitive and specific covid- rdrp/hel real-time reverse transcription-polymerase chain reaction assay validated in vitro and with clinical specimens temporal profiles of viral load in posterior oropharyngeal saliva samples and serum antibody responses during infection by sars-cov- : an observational cohort study covid- in persons with mild upper respiratory symptoms on a cruise ship hong kong's poor live in homes smaller than prison cells-study can we contain the covid- outbreak with the same measures as for sars? gastrointestinal manifestations of sars-cov- infection and virus load in fecal samples from the hong kong cohort and systematic review and meta-analysis travellers and influenza: risk and prevention incidence and risk factors of diarrhoea in dutch travellers: consequences for priorities in pre-travel health advice early transmission dynamics in wuhan, china, of novel coronavirus-infected pneumonia covid- outbreak progression in italian regions: approaching the peak by the end of march in northern italy and first week of april in southern italy pattern of early human-to-human transmission of wuhan audio interview: what clinicians need to know in diagnosing and treating covid- sars-cov- viral load in upper respiratory specimens of infected patients effect of clinical and virological parameters on the level of neutralizing antibody against pandemic influenza a virus h n host immune response to influenza a infection severe acute respiratory syndrome coronavirus -specific antibody responses in coronavirus disease patients singapore claims first use of antibody test to track coronavirus infections radiological findings from patients with covid- pneumonia in wuhan, china: a descriptive study we thank all our health-care and laboratory colleagues from the queen mary key: cord- -sig h authors: yeung, may ps; ng, stephen kam-cheung; tong, edmond tak fai; chan, stephen sek-kam; coker, richard title: factors associated with uptake of influenza vaccine in people aged to years in hong kong: a case–control study date: - - journal: bmc public health doi: . /s - - - sha: doc_id: cord_uid: sig h background: in hong kong, people aged – years were added as a recommended priority group (recommended group) for influenza vaccination by the department of health (dh) starting from / onwards. the coverage rate of influenza vaccination for this age group was suboptimal at . % in / . this study investigates the factors associated with the uptake of influenza vaccination among adults in hong kong aged – years. methods: a case–control study was conducted in communities by street intercept interviews from july to august . cases were adults aged – years who had received the influenza vaccine in / or / , while controls were the same as the cases, except they had not received the influenza vaccine in / or / . multiple logistic regression analysis was performed on the data to explore the associations between vaccination status and the variables. results: six hundred and four respondents in total were interviewed and included in the analysis. there were cases (vaccinated) and controls (non-vaccinated), with a case-to-control ratio of : . . the following were strongly associated with vaccination compared to other factors: ‘eligible for free government vaccine’ (or . , % ci, . - . , p < . ); ‘willing to receive flu vaccination for free’ (or . , % ci, . - . , p < . ); ‘perceived having severe or moderate symptoms when contracting flu’ (or . , % ci, . - . , p = . ), and ‘convenient to reach a vaccination location’ (or . , % ci, . - . , p = . ). the majority of the cases ( . %) and controls ( . %) were not aware that they belonged to a recommended group for influenza vaccination and most (> %) were willing to be vaccinated if it was free. conclusions: factors related to free and convenient vaccination, the perception of the severity of symptoms when contracting influenza had a comparatively strong association with influenza vaccination uptake amongst – year olds, compared to other factors. seasonal influenza vaccination (referred to as 'influenza vaccination' , 'vaccination' or 'vaccine' , below) remains an effective measure to protect individuals and communities from severe morbidity and mortality induced by influenza. to mitigate the disease burden of influenza, many developed countries recommend vaccination for high-risk groups. some exceptions are the united states (us), austria and estonia, which have universally recommended people aged months or above to receive influenza vaccination [ ] [ ] [ ] . few european countries, such as belgium and ireland, included those aged - years in their recommended groups [ ] . although the vaccine did not provide an overall economic benefit in some communities, it yielded significant health benefits by reducing severe complications from influenza [ , , ] . meta-analysis and literature reviews demonstrated that the influenza vaccine had a moderate effect in reducing the clinical symptoms of influenza in healthy people from to years [ , ] . many middle-aged adults have undiagnosed medical conditions, such as diabetes mellitus, and are at higher risk of severe influenza-related complications [ , ] . in hong kong, people aged - years were added as a recommended priority group (recommended group) for influenza vaccination by the department of health (dh) starting from / [ ] . the major driver behind this inititiative was a real increase in influenzaattributed intensive care unit (icu) admissions and deaths among the middle-aged group in / , [ ] plus an anticipated increase in the years to come when the influenza a(h n )pdm strain was predicted to circulate in the population. after this new vaccination policy was launched, however, the vaccine was not well received and the vaccination coverage in this new target group was very low at . % [ ] . no free or subsidised influenza vaccination service was provided by the government to this group, except those who already belonged to the other free or subsidised recommended high-risk groups and those with financial difficulties, i.e., comprehensive social security assistance (cssa) recipients. healthy - year olds, without other risk indicators, had to pay if they wanted to be vaccinated. this study aimed to find out which factors were associated with the low uptake of influenza vaccination among people aged - years in hong kong. a survey was conducted in a community setting in hong kong from july to august , following which a case-control analysis was used to investigate the study hypothesis. street intercept interviews were undertaken in districts (out of a total of in the territory). cases were (i) those who received the influenza vaccine in / or / , i.e., from september to august ; (ii) aged - years in - ; and (iii) citizens who were resident in hong kong. controls were the same as the cases in (ii) and (iii), except they had not received the influenza vaccine in / or / influenza seasons. some controls had received the influenza vaccine before september . they were classified as control because they were not included as the recommended group in / and before. the sample size was calculated with a significance level of . (two-sided) and a power level of . . the calculation of the sample size was done by the fleiss formula for unmatched case-control studies with dichotomous exposure variables. a minimum sample size of was required with a case-to-control ratio of : [ ] . the interviewers were assigned a random time slot, covering weekdays, weekends, office and non-office hours. the questionnaire was conducted in summer before the next influenza vaccination season, which usually begins in september of each year. primary data were collected by four trained research interviewers who were fluent in chinese and english. the interviewers were stationed in areas of high pedestrian traffic, such as near underground train stations and shopping malls, during the assigned random time slot. this research had been approved by the human subjects ethics sub-committee of the hong kong polytechnic university and the ethics committee of the london school of hygiene and tropical medicine. before each interview, the interviewer would inform the respondent about the nature and purpose of the study and invited their voluntary participation. interviewees were asked to respond only after informed consent was obtained. no incentive was given. the hypothesis of this study was there were differences in associated factors (variables) between those hong kong residents aged - years who received the influenza vaccine in / and / , and those who did not. the null hypothesis assumes no such association. the questionnaire was designed with reference to past vaccination questionnaires from health authorities [ , ] and relevant studies [ ] [ ] [ ] . the draft questionnaire was then sent for comment to a multi-disciplinary team, comprised of an infectious disease specialist, an epidemiologist and general practitioners. the questionnaire was in chinese and english and had questions including on demographic data and covering the factors (variables) to be examined. statistical analyses were performed using the software sas . . categorical demographic data and variables were compared using the pearson chi-square test, crude and adjusted odds ratios (ors) with corresponding % confidence intervals (cis) and p-values. multiple logistic regression analysis was performed. any variables with p values < . and those with important associations demonstrated in the literature were selected for regression analysis (backward stepwise regression algorithms). the regression model is a built-in formula in the sas software. all statistical tests were two-tailed and variables were considered significant at a significance level of . . the study included cases (vaccinated) and controls (non-vaccinated), with a case to control ratio of : . . this sample size reached the required range in the sample size calculation. the average interview time was min (standard deviation ± min) for each questionnaire, and the response rate was . %. during street intercept interviews, there were more non-vaccinated individuals (controls) than vaccinated ones (cases). after the required number of non-vaccinated was recruited, the excess approached by the interviewers were counted as non-responders. in total man-hours were spent on the interviews. the differences between baseline demographic data of cases and controls were statistically insignificant regarding sex, ethics, education level, employment status, personal monthly income, current smoking and drinking status. the demography of cases and controls are shown in table . there was no apparent discrepancy in the sample and the target population. one exception was in the sampled respondents; there were proportionally higher numbers of females than males (m:f = : . ), while the overall ratio in the target community was : . other demographic parameters of the sampled population, such as the age proportion between groups, education level, ethnicity, and the percentage of those in employment, were comparable to the target population (i.e., hong kong general population aged - years). the majority of the respondents were chinese, and there were more female than male respondents ( . % vs . %). most ( . %) of those who were in employment were aged years or below. overall, half of the respondents ( . %) had no income. one in four ( . %) was a housewife and one fifth ( . %) was retired. the majority of them ( . %) had received at least years of education up to secondary level. the majority of all the cases ( . %) and controls ( . %) were not aware that the health authority had recommended vaccination against influenza. however, the cases were more aware of the recommendation for influenza vaccination than the controls, (or . , % ci . - . , p = . ). there were health knowledge differences between the cases and controls in all the questions asked on knowledge, including government vaccination services, vaccine reduction in influenzarelated hospital admission, and vaccine protection for healthy adults. however, these associations were statistically insignificant after the or was adjusted ( table ) . when compared to the controls, more of the cases had chronic diseases; more frequently 'visited doctors in the past months' and 'lived with children below years or elders above years'. however, none of these associations was statistically significant after the or was adjusted. there was no association between vaccination and smoking/drinking. most cases ( . %) stated that they were likely or very likely to receive the vaccine in / , compared to only . % among the controls. this implies those who had previous vaccinations in / and / would choose to be vaccinated again in the future. in general, more cases perceived there to be a higher risk of contracting influenza in the next months and/ or having severe influenza or moderate symptoms when there were no associations between differences in response to the government telephone reminder service for vaccination, if there was one. in respect of vaccination, the cases were more heavily influenced by others' opinions and actions than were the controls. when compared, more cases would 'accept advice from health professionals' (or . , % ci . - among the controls (i.e., never received vaccination or received vaccine on or before / ), . % of them had previously received the vaccine. the following were common reasons given by the controls for not receiving a vaccine: considered vaccination unnecessary ( . %); believed they were not in a high-risk group ( . %); and concerns about side effects of vaccination ( . %). of the controls that had previously been vaccinated, % had received the vaccine at a public clinic. a subgroup analysis was performed on those who received influenza vaccination but did not know they were recommended group by the department of health (dh). there were cases (who were vaccinated) and among them answered yes to "knowing oneself to be in the recommended group for flu vaccine" and answered no. in these people the five commonest reasons for vaccination were: advice from healthcare professionals ( . %), vaccine was useful in protect oneself against flu ( . %), flu shot had additional benefits, e.g. protect family member ( . %), perception of not having very good or good health ( . %) and eligible for free government vaccine ( . %). more than half ( %) of these people received their influenza vaccine at government public clinics, and most of the remaining ( %) at private general practitioners. this is a case-control study with vaccination status as the 'outcome' and personal or external environmental factors as 'exposures'. a case-control study design was chosen because of a low prevalence of eligible cases. a street intercept interview method enabled the interviewers to screen and approach a larger number of people, according to the outward appearance of their age. this probably lowered the rejection rate and enabled a greater control in completing the questionnaire. it was estimated that a larger number of people would have had to be approached should a telephone or postage survey been used. the low response rate ( . %) was attributable to the difficulty in finding cases, as the excess controls approached by the interviewers were counted as non-responders. moreover, the interviews were conducted in summer time when the street temperature was > °c, the streets were crowded and no incentive was offered. multi-dimensional factors have contributed to people's choice of whether or not to receive vaccination. these factors comprise of social, environmental and economic dynamics in a specific context. the factors were put in a multiple logistic regression model and statistically adjusted for age, employment status, in receipt of social security, and all independent variables. before statistical adjustment, most of these factors had statistically significant crude odds ratios. the variables affected each other and many became non-significant after adjustment. there would be a confounding effect between variables. the majority of the cases ( . %) and controls ( . %) were not aware that they were in a group recommended by the health authority to receive influenza vaccination. among the controls, a higher percentage ( %) deemed vaccination to be 'unnecessary'. this revealed a failure of dh and health professionals in communicating the message that 'vaccination is recommended' to this age group. given that there was an association between 'knowing oneself to be in the recommended group for flu vaccine' and vaccination, better communication of the risks might have improved the vaccination rate. a health promotion strategy on empowerment and enhancement of knowledge on this issue needs to be planned and supported by health-care policy. studies suggested that previous influenza vaccination was a predictor for subsequent vaccination (or . - . ) [ ] [ ] [ ] [ ] . however, past behaviour does not provide an insight into the reasons why a person chooses to be vaccinated. the vaccination coverage rate is price sensitive. this was demonstrated in this study and in countries which provided vaccine reimbursements to users [ , ] . to receive influenza vaccination, most ( %) people aged - years in the general hong kong population had to pay out-of-pocket. in this study, the odds of the cases being 'eligible for free government vaccine' were . times the controls. among the cases, half ( %) of them attended a private clinic or hospital and paid the vaccination fee. many study cases and controls expressed they were willing to receive the vaccine if it was free or subsidised. such a vaccination service could possibly increase the vaccination rate. there was only a mild association between chronic disease(s) and vaccination and the association was insignificant after the or was adjusted (or . , % ci . - . , p = . ). this result contradicted the findings of many studies that indicated that the presence of chronic diseases was one of the most persistent factors associated with vaccination [ , , [ ] [ ] [ ] [ ] [ ] [ ] . ' accept advice by health professional' was moderately associated with vaccination (or . , % ci . - . , p = . ). several other studies have shown that doctors' and health professionals' advice was associated with influenza vaccination [ , ] . health professionals had a duty to recommend vaccination to high-risk groups in order to protect them from influenza and severe complications. 'had family member received flu vaccine' was associated with people's uptake of the vaccination, but 'accept advice from relatives and friends' was not. in japan, advice from health professionals, family and/or close friends was strongly associated [ ] . in the usa and other western countries, advice from family and/or close friends was not a significant factor in acceptance of influenza vaccination [ , ] . this could possibly be due to the differences in cultural backgrounds between individuals in these countries. this study showed no association between vaccination and smoking and drinking. it is uncertain whether people were consistent in their health behaviours. studies have proven that smoking is not associated with vaccination [ , ] . no data was found on other health behaviours, such as drinking or frequent exercise, having a link to vaccination. given past experiences of infectious disease epidemics in hong kong, people may be more inclined to receive vaccination to protect themselves in anticipation of the occurrence of a disease epidemic such as sars or swine influenza. previous research has suggested that newly issued recommendations are not quickly embraced by the majority of citizens. in the us, government national health interview survey data did not show a marked increase in vaccination rates among adults aged - and - years after the us advisory committee on immunization practices expanded its recommendations to these subgroups in and , respectively [ , ] . this vaccination policy limited the government vaccination free service to those suffering economic hardship and chronic diseases among - year-olds. although the price of receiving an influenza vaccination constitutes a minute percentage of monthly income, this does not necessarily mean socio-economically deprived groups who are ineligible for free vaccination would be willing to pay for the vaccine. subsidised vaccination would attract those who are willing to pay at a discounted price. health providers could be engaged, with or without incentives, to promote the benefit of vaccination. in addition, dh should consider health promotion messages addressing factors with strong associations to encourage payment by the individual. these factors included 'the perception of having severe or moderate symptoms when contracting flu' , 'knowledge of being in the recommended group for flu vaccine' and 'good vaccine protection for healthy adults'. a case-control design enabled the measurement of many different exposures at once and for the combined effects of exposures to be examined. in addition, data were collected within a short time-frame. one of the important limitations of this case-control was the temporal sequence and reverse causality. it is difficult to interpret the time sequence of the exposures and the outcomes. for example, it is uncertain whether perception of the safety of the influenza vaccine was a cause or a consequence of vaccination. other limitations of this casecontrol include the information and recall bias of the respondents, and the inability to estimate the coverage of vaccination in this age band. one limitation of using the street-intercept method would be the possibility that the interviewers approached those who looked - years and, potentially missed a number of younger and older looking individuals; the extent of this bias is difficult to assess. another bias would be due to the sampling of respondents from different locations, e.g., on public and private estates, in train stations and shopping malls. a comparison of the demographic characteristics of the samples collected in different locations, and those of the relevant population, would be useful to identify potential bias. the study results have important implications for the general population aged - years in hong kong. there would be considerable differences between cultures, beliefs, norms and external environments -such as health systems and service provision -which have to be taken into consideration when applying the results to other populations. further studies on the local vaccination policy and the views of health professionals would provide a comprehensive account of the low vaccination coverage in this age group. factors related to free and convenient vaccination, perception of the severity of symptoms when contracting influenza had a comparatively strong association with influenza vaccination uptake among - year olds, compared to other factors. differences in national influenza vaccination policies across the european union, norway and iceland risk groups and other target groups -preliminary ecdc guidance for developing influenza vaccination recommendations for the season - prevention and control of seasonal influenza with vaccines. recommendations of the advisory committee on immunization practices-united states influenza vaccination in austria from to : a country resistant to influenza prevention and control the effectiveness of vaccination against influenza in healthy, working adults effectiveness and cost-benefit of influenza vaccination of healthy working adults: a randomized controlled trial vaccines for preventing influenza in healthy adults efficacy and effectiveness of influenza vaccines: a systematic review and meta-analysis undiagnosed diabetes-data from the english longitudinal study of ageing seasonal influenza (flu) specific groups: people at high risk ofdeveloping flu-related complications scientific committee on vaccine preventable diseases. recommendations on seasonal influenza vaccination for the seasonal influenza vaccination coverage survey for the / season statistical methods for rates and proportions seasonal influenza vaccination survey in eu/eea, influenza season - . venice ii consortium department of health. evaluation of the publicity of human swine influenza vaccination programme development of a survey to identify vaccine-hesitant parents: the parent attitudes about childhood vaccines survey influence of family on acceptance of influenza vaccination among japanese patients survey on hong kong citizens' knowledge and opinion of influenza vaccination hong kong prevalence of influenza vaccination and correlates of intention to be vaccinated among hong kong chinese comparison of different risk perception measures in predicting seasonal influenza vaccination among healthy chinese adults in hong kong: a prospective longitudinal study influenza vaccination uptake among the working age population of japan: results from a national cross-sectional survey predictors of influenza vaccine acceptance among healthy adults influenza vaccination in europe: an inventory of strategies to reach target populations and optimise vaccination uptake seasonal influenza vaccination coverage rates in countries in africa vaccination coverage rates in eleven european countries during two consecutive influenza seasons influenza vaccination uptake and socioeconomic determinants in european countries patient's perceptions and information provided by the public health service are predictors for influenza vaccine uptake factors influencing acceptance of influenza vaccination given in an ed predictors of flu vaccination among urban hispanic children and adults influenza vaccination coverage against seasonal and pandemic influenza and their determinants in france: a cross-sectional survey healthy young and middle age adults: what will it take to vaccinate them for influenza? vaccine patient acceptance of influenza vaccination compliance with influenza vaccination. its relation with epidemiologic and sociopsychological factors no intention to comply with influenza and pneumococcal vaccination: behavioural determinants among smokers and non-smokers behavior and beliefs about influenza vaccine among adults aged - years we would like to thank the interviewers from the hong kong rehabilitation power; cathel hutchison for providing the language editing service; and ss lee, nguyen-van-tam and mark jit for their invaluable expert opinions. authors' contributions mpsy was the principal investigator and generated the research framework and methods, collected, analysed, interpreted the data and drafted the manuscript. skcn and etft contributed to the study methodology, analysis and revision of the manuscript. sskc contributed to the questionnaire design and statistical analysis. rc contributed to the conception, design, analysis and interpretation of the study, and critically revised the manuscript. all authors read and approved the final manuscript. key: cord- -elzkwyz authors: day, brennan; burnice mckay, ruth; ishman, michael; chung, ed title: the new normal: lessons learned from sars for corporations operating in emerging markets date: - - journal: nan doi: . / sha: doc_id: cord_uid: elzkwyz the modern industrialized world was completely caught off guard by the recent sars outbreak. fortunately, for most organizations, the impact has been short lived, but management has been provided with a reminder of the impact of the external environment in a world of ever increasing globalization. as seen with the sars outbreak, a lack of preparedness can have devastating effects on business and warrant inclusion in a business definition of a crisis. this paper uses the recent sars epidemic as a background to highlight the importance of crisis planning, particularly in emerging economies, and suggests how organizations can address these concerns. the implementation of environmental scanning in strategic planning is critical to the survival of an organization. that businesses operate in the context of some larger system, not a vacuum, is today part of the accepted business perspective. however, we ought to recognize that scanning and the related processes of contingency planning presume our ability to discern future patterns. many well-known business mistakes, such as the big three's disastrous handling of the energy crisis in the s, can be attributed as much to inadequate managerial skills as ignorance about environmental trends. after all, it was not any existing predators that eradicated the dinosaurs, but instead it was something never before seen and hence could not have been anticipated. the fact that the meteor was not in the dinosaur's vernacular did not prevent a meteor from changing the course of earth's history. the scope of our environmental scanning activities expands as our knowledge increases. such scanning is informed by new developments that have often been prospering just below the corporate radar screen. the recent (and arguably not over) sever acute respiratory syndrome (sars) outbreak is a case in point. even though contagious diseases are well-known, and their fatal impact acknowledged, e.g. pneumonic plague, spanish-flu and bubonic plague, the world was caught completely off-guard by the sars outbreak. despite superhuman efforts by the many health-care workers around the world, it was months (and many deaths) before the world health organization pronounced the epidemic temporarily halted. the health-care establishment could not have predicted the outbreak. as devastating as it was for many businesses, strategic planners would have to be psychic to have anticipated the disease and to incorporate it in the planning process. however, it would be useful to delineate lessons that can be learned from the recent sars (and other) outbreaks, and discuss how strategic management may benefit from an appreciation of these lessons. in preparation for unforeseen external events organizations should have a plan in place to reduce the influence on the organization and provide an operation manual in the event of a crisis. however, many fortune , firms do not have a crisis-management plan at all (hickman and crandall, ) . as seen with the sars outbreak this lack of preparedness can have devastating effects on business and warrant inclusion in our business definition of a crisis. a crisis is defined as a low probability/high consequence event, caused by human actions, that threatens the most fundamental goals of an organization (weick, ) . mitroff and pearson ( ) categorized crises according to two dimensions: normal to sever and technical/economic to human/social. however, their crisis analysis included only industrial health problems, not epidemics. there is a need to broaden the scope of crisis to include epidemics. our paper aims to provide this addition. this paper will start by presenting background information on the sars epidemic and the impact on organizations, especially those operating in emerging markets. next, characteristics of countries termed emerging markets will be identified and the inherent risks and challenges organizations face operating in these markets will be discussed. third, we offer recommendations for minimizing the impact of operating in an emerging market where contagious diseases are a reality. this represents an important first step towards developing (and implementing) a robust contingency plan for purposes of business continuity. on the basis of purchasing power parity, emerging and developing economies account for percent of the world's economy (gingrich, ) . conservative predictions conclude that by the year the developing world will account for over percent of the total world output (belous et al., ) . given the substantial growth in these economies, it is not surprising that the us department of commerce's international trade administration recently predicted that the greatest commercial opportunities will be found in the big emerging markets such as the people's republic of china (china), india, singapore, mexico, vietnam, or south africa (qureshi, ) . china provides perhaps the clearest illustration. for example, in china received $ billion in direct foreign investment, overtaking the united states to make it the world's biggest recipient of direct foreign investment (buckman, ) . according to the us bureau of economic analysis in , china and hong kong accounted for nearly a quarter of the income of us overseas subsidiaries (karmin, ) . however, the recent sars outbreak has shown how quickly commerce can be impacted in the global market. according to richard miller, an economist and vice president of the world travel & tourism council: "never before has there been a massive impact of this nature other than a war shutting down an economy totally" (prystay, ) . as of june , , outbreaks of sars have occurred in countries, resulting in , individuals being infected and subsequent deaths (world health organization, ) . economists are predicting that china, as a result of sars may see gdp growth drop below percent to its lowest level in nearly a decade (leggett, ) . some areas have been hit more harshly than others. in the chinese province of guangdong, the place where sars is believed to have started, the country's largest export-trade fair saw orders drop in april nearly percent (leggett, ) . in beijing, draconian measures were imposed to try to stem the spread of sars. public schools and universities were closed, migrant workers were told to stay in the capital and make-shift roadblocks were set up in villages to prevent city dwellers from entering (kaufman and chen, ) . in may, hong kong retail sales were down to percent, restaurants and their suppliers were going broke and hotel occupancy rates were in the single digits. airlines were also severely impacted. cathay pacific airway during this time dealt with an percent decrease in air traffic from a year earlier (meredith, ) . such a decrease in travel is not surprising given the overall drop in business air travel globally. in a survey conducted by the society for human resource management in the usa, based on human resource professionals, percent reported cuts in employee travel as a result of sars (usa today, ) . kingsway international holdings limited, a hong kong investment holding company that engages in securities brokerage, corporate finance advisory services, fund and asset management, securities investments, and strategic investment in technology-related businesses has seen earning per share drop from $ . in june to $ . in june . the company attributes the results to the difficult operating conditions including the influence of sars (infomart, ) . march sales of desktop computers in hong kong plunged percent, laptop sales dropped percent and mobile-phone sales fell percent (leggett, ) . cell phone sales dropped percent in guangzhou, the shanghai auto show only drew one quarter of its expected visitors and motorola shut its -story asia pacific headquarters building in beijing (engardio et al., ) . businesses located in developed nations have also been impacted. in australia, some small-to-medium sized businesses could face losses of up to $ million due to sars. westpac bank has predicted that sars could reduce australia's economic growth by . percent (chong, ) . multinational corporations are also being impacted. for example m, the makers of the n face mask, one of the few face masks that are percent effective at filtering out airborne diseases like sars, does percent of its $ billion in annual sales in the asia pacific region. j.p. morgan lists m as well as intel and united technologies as american companies that could be hurt by sars (freedman, ) . other companies suggesting revenues will be down as a result of sars include american international group inc., yum brand inc., goodrich corp. (karmin, ) and cara operations ltd. (flavelle, ) . another industry feeling the impact of sars is the phone makers. motorola, a company holding percent of the chinese mobile phone market, has warned that it may fall short of sales and profit forecasts for the second quarter and year end citing weakening demand in asia because of sars (timmons, ) . four season's hotel inc. has a net loss in the first quarter of cents per share compared to net income of cents per share a year earlier (infomart, ) . sars is seen as a key contributor to this loss. the city of toronto also provides an indication of the economic impact of sars claiming the cost to the government for health care and income compensation for those quarantined for the first six months of totaled us$ million (chowdhury, ) . while the above figures are indicators of the effect of sars, the true impact may never be known. it is believed that china, in order to maintain a semblance of stability and economic prosperity at the time of changing government leaders, covered up the md , truth about the extent of sars. it went so far as to remove sars patients from hospitals to deceive inspectors from the world health organization (jue, ) . in april, jiang yanyong blew the whistle on chinese authorities' deceit regarding the truth about sars in beijing. in a letter to journalists, when beijing was saying that only people in the city were infected with sars, dr jiang disclosed that the true number of sars patients was at least , including ten who had died. in response to dr jiang's revelation the health minister and beijing mayor were fired. for a regime with a long history of deception and denial, this event has been viewed as a revolution in official openness (york, ) . in a step to reinforce openness the chinese government has threatened to execute anyone who knowingly spreads the sars virus (dean, ) . however, this may have the reverse impact of making people hesitant to admit they have sars for fear of punishment. by lying about the true number of sars patients, beijing damaged what little faith international economist has in its numbers. for example, repeated yearly claims of percent annual gdp may be questionable. for the new chinese leadership the incentive to cheat is even greater than usual. strong gdp growth has been the key to the communist party's hold on power. the new government would not want to be associated with instant economic failure (august, ) . in addition to the sars outbreak there is news that another deadly virus has emerged in southern china through the winter. the associated press ( ) reported an outbreak of encephalitis in southern china that has (at time of writing) affected several hundred people and resulted in more than a dozen deaths. at the same time as this new disease is spreading in china and hong kong, the government in hong kong is pushing ahead with tough new security laws which journalists fear could inhibit future reporting of crisis. under the new legislation reporters could well be jailed for publishing details of state secrets and confidential communication between hong kong and beijing. thomas crampton, president of the foreign correspondents club of hong kong stated that in a country where health statistics are a state secret the legislation "puts a pall of uncertainty over reporting in hong kong. it encourages self-censorship" (korporaal, ) . for businesses operating in this and related regions, another outbreak and the possibility of another chinese cover up could not be good news. while it is hard to beat the wage rates of to cents an hour in china, it is a constant corporate challenge to operate in an environment where propaganda and obfuscation are used as government marketing tools. given the rapid onset of sars, the presence of other contagious diseases in the world and the government and infrastructure challenges for corporations operating in emerging markets, it is essential that corporations are prepared for future contagious disease outbreaks. it is not clear if sars can be eradicated. the disease could gain a toehold in the southern hemisphere, or it could lie low until cold weather returns (regalado, ) . while sars is taking the center stage, areas in europe are dealing with another disturbing virus that is spreading among chickens and in some cases humans. the avian flu has been found in the netherlands, belgium and germany. the virus, which rarely causes serious illness in humans, infected people who came in contact with infected birds (fuhrmans, ) . it is also conceivable that corporations may be operating in regions of the world where they will face bio-terrorism. as an indication of the possibility of such sabotage the us department of justice and the federal emergency management agency staged a mock terrorist attack on chicago airports in may . this is the second such exercise, the first being staged at a denver concert hall in may . in this year's exercise, terrorists sprayed unseen germs over chicago airports, infecting thousands with a lethal pneumonia. the exercise was undertaken to determined level of preparedness in the event of bio-terrorism (chase, ) . according to the australian state chamber of commerce chief executive officer, margy osmond, "(t)he lack of preparation by many businesses in terms of handling workplace issues and risks arising from the (sars) virus is . . . a concern". she also notes that percent of corporate respondents had a risk management plan to deal with potential disruptions created by sars but only percent had made this plan known to their staff. benefits of a fast response can be seen in the fast reaction of the canadian health authorities dealing with sars preventing the outbreak from reaching unmanageable numbers. according to castillo-chavez, a mathematical epidemiologist at cornell university, if the canadian outbreak had been left to run unchecked it could easily have infected as many as , in the toronto area (brown, ) . the toronto sars experience is a warning that even a giant thriving city can be laid low by a nasty and highly contagious disease (vogel, ) . since emerging markets are increasingly important to the world economy and are at the same time susceptible to outbreaks of infectious diseases, we need to understand how we are linked together on an interdependent global level. that interdependency is highlighted in the following section. the days of national economies existing as relatively self-contained entities are rapidly disappearing. individual economies are no longer isolated from each other by barriers to cross-border trade and investment -by distance, time zones, and language -and by national differences in government regulation, culture, and business systems. national economies are merging into an interdependent global economic system and, consequently, the rich industrial countries are dominating the world economy relatively less than they used to. at the beginning of its fiscal year (ending on june ), countries had been identified by the world bank as developing economies (international bank for reconstruction and development /the world bank, , p. ). the developed world, however, currently represents more than percent of total world output, while the developing nations represent less than percent. this proportion is poised to change in the near future though, with conservative projections indicating that by the situation could be reversed, with the developing world representing well over percent of total world output (belous et al., , p. ). the developing countries that have been the frontrunners in economic advancement have been designated as emerging economies by the economist. this classification is based on both the gross domestic product of each nation and the capitalization of their stock markets. these countries have historically played an unparalleled role in the global economy -a role that is well positioned to steadily expand in international importance. the emerging economies are home to approximately percent of the world's population and the population growth rates of these economies are the highest of all countries. the five largest developing nations, home to . billion people, have a combined population that is four times that of the g- countries. the populations of china and india alone, . billion and more than billion respectively, easily outnumber those of many developed countries combined (cavusgil et al., , pp. , ) . many of the world's developed countries now have birth rates below those that are required to maintain their present population levels. furthermore, individuals in the developed world are living progressively longer and leaving the work force earlier. with fewer workers generating output, and with more of the population dependent on those who do, income growth, savings levels, and economic growth will all be lower. in contrast, the populations of emerging countries are comparatively young. the working-age population in these markets -which will be the portion of the population driving economic and consumption growth -will grow at rates three to four times that of the developed world. the emerging markets also offer a large pool of low-cost, unskilled labor and it has become increasingly commonplace for large, multinational corporations to transfer their assembly and production plants from developed locations to these areas (gingrich, ) . the size of the consumer markets in the emerging countries now rivals those of the developed markets in many cases. for instance, the combined gross domestic product of the ten largest emerging markets is now nearly two-thirds the size of that of the g- counties in purchasing power parity terms. five emerging economies -china, india, brazil, mexico, and indonesia -are among the largest economies in the world and have a combined purchasing power already half of that of the g- . according to the international monetary fund (imf), developing countries will achieve a growth rate of more than percent per year over the next two decades, whereas industrialized countries are likely to average . percent (cavusgil et al., , p. ) . if just three of the asian emerging economies -china, india, and indonesia -are able to maintain this growth rate of percent per year, the organisation for economic co-operation and development (oecd) has estimated that by approximately million people in those countries will have an average income equivalent to that of spain today. as a group, they are roughly equivalent in population to the usa, japan, and europe combined (us department of commerce, , p. ). given these trends, multinational corporations (mncs) face profound changes in the economic landscape. over the next to years, most of the total world growth in consumption of consumer goods will likely be concentrated within the emerging economies. the emerging markets have also become major suppliers of many of the natural resources that the industrialized world relies on. for example, mexico, venezuela, and indonesia, in addition to several middle eastern countries, are major sources of oilstill the most vital energy source for developed countries. similarly, brazil, russia, and china, along with developing countries papua new guinea and jamaica, supply half of the world's bauxite (aluminum ore) (day, , p. ) . looking to the future, the supplier role of the emerging countries will expand since the exploitation of natural resources in many of the wealthy countries has reached its limit. either the oil fields, mines, or forests have been tapped out, or environmental regulations reduce new exploration and development. industrialized nations are therefore becoming increasingly dependent on emerging markets to ensure that sufficient levels of natural resources are available. overall, development in the emerging markets has been steady, but none of these countries have been fortunate enough to avoid certain growing pains along the way. one historical trend of many emerging markets is the inability of their currencies to hold value. rather than attack the principal causes of currency depreciation, many governments opt instead for a short term, cosmetic solution. after several years of declining currency value, they might print a new currency that "lops off two zeros" from the denomination of the older currency (hooke, , p. ) . in , for example, mexico initiated the new peso that was worth , old pesos. these superficial actions diminish investor confidence. additionally, widespread corruption exists in virtually all emerging markets, with hong kong and singapore being the most notable exceptions. many politicians view a government career as similar to a private sector job, with one primary goal in mind: making money. with many top officials setting a poor example, low-level bureaucrats are active in demanding payments for business licenses, permits, and concessions. since public sector jobs, as compared to a private sector position, have low salaries and no stock options, the difference is often made up through bribes and insider deals. public employees and elected officials accept these prerequisites in exchange for government contracts, licenses, and privileges (hooke, , p. ) . environmental issues in the emerging world often run unchecked. due to their size, their growing industrialization, and the urgency they attach to business expansion and job creation, many emerging markets have barely begun to put in place effective environmental programs. they often lack, or claim to lack, the financing capability to address the environment at this stage of their development, especially in light of competing priorities such as infrastructure. despite these ever-present risks and challenges that exist in the emerging world, the staggering economic impact of many of these countries coupled with their substantial population growth has created a growth potential too significant to be ignored by the developed world. accordingly, many private sector and government analysts continue to point to emerging markets as a potential major source of western economic growth and profit in the coming years (day, , p. ) . over the past three decades emerging markets have consistently shown growth rates well above those of more mature economies and this trend is expected to continue. the economies that make up the emerging world will almost undoubtedly have an even greater impact on the overall global economy throughout the foreseeable future. emerging markets can present tremendous opportunities as well as unforeseen challenges for global organizations. the recent sars epidemic highlights how a disease centered in countries identified as emerging can create formidable obstacles for managers. in order to examine the potential long-term effect of sars on emerging economies, an examination of infectious disease is required. the next section provides a brief historical look at the impact of epidemics on communities and organizations. despite the advents of modern medical science, infectious diseases such as malaria continue to wreak havoc. "if seven boeing s, filled mostly with children, were crashing into mount kilimanjaro each day, something might be done about it. that, in the memorable phrase of wen kilama, a tanzanian researcher, is roughly the scale of the carnage wrought by one disease, malaria, mainly in africa" (the economist, ) . more recently, the spread of sars captured center stage, due as much to the disease's proclivity as to media's desire for the next major headline. augmented or not, that sars has been (and may continues to be) destructive is unequivocal. indeed, because md , most of the inflicted jurisdictions are important developing economies, sars poses serious implications for businesses around the world. as surowiecki ( ) noted in the new yorker magazine, "before sars, china was going to be the factory floor to the world. now it has to worry about becoming the sick ward of the east". it is important to note, however, that menacing as sars is, it is but one epidemic in a long series of infectious outbreaks that have plagued human history. and in spite of its highly vilified image, sars has caused relatively minor damage compared to past epidemics. as one commentator puts it, "sars has not yet reached the scope or virulence to be described as a pancosmic. so far it is a fleabite compared to previous plagues. you are more likely to be struck by lightning than sars" (howard, ) . a history of plagues is beyond the scope of this paper. however, it is important to offer some background on infectious diseases and their impact on humanity over the centuries. we also wish to point out that, quite aside from sars, infectious diseases (some with much more deadly and rapid effects) continue to threaten the world. while most have heard of the black death and yellow fever, perhaps the most famous plague of all happened centuries ago in athens ( - bc). though it is impossible to know with certitude what the disease actually was, it was of such devastation that even vultures refused to touch the corpses of the dead (howard, ) . fast forward to the s, black death swept across europe. as "recently" as the seventeenth century, the great plague of london killed , people, followed by the plague that killed up to , people in china and hong kong. indeed, within the next years, plagues had killed more than million people worldwide. lest we thought the plague is a thing of the past, outbreaks of bubonic and pneumonic plagues in killed more than in india (king, ) . recent reports by the washington post suggest that rotaviral infections, a virus that causes acute gastroenteritis, are fast becoming an emerging problem in the former soviet union. north america has never been exempt from the devastations of infectious diseases. the advance of european cultures over first people in north america, such as the mohawks and algonquin nations, was due to the importing of diseases such as tuberculosis (tb) that devastated the established cultures killing millions of people. yellow fever ravaged philadelphia in , killing thousands in the then capital of the usa (dalrymple, ) . in and , spanish influenza killed more than half a million people in the usa alone (king, ) , and many insurance companies saw their profits wiped out and had to reduce dividend payments because of the claims made from the illness (bell, ) . today, tb is perhaps one of the most lethal infectious diseases. even though was the tenth consecutive year of declining tb cases in the usa, each year some two million people die from tb and an estimated one-third of the world's population is infected with the bacteria (center for disease control, ) . other diseases such as malaria and ebola continue to claim the lives of thousands, and since they occur predominantly in under-developed economies with poor infrastructure and health services, their effects are staggering. a disease like ebola, for example, can have mortality rates as high as percent (washington post, ) . it is informative to note the difference between epidemics and endemic diseases, though with the ease of modern travel and human contacts, the lines are somewhat blurred. endemic diseases are those that are localized in certain regions. unlike epidemics which really have no "home base," so to speak, endemic diseases are associated with particular geographic locations (surowiecki, ) . usually because of inadequate infrastructure, these jurisdictions are ill-equipped to stem the disease. the disease not only negates current economic growth but also acts as a barrier to future economic growth since investment flows tend to avoid these regions where companies remain concerned about the health of their employees. as business becomes increasingly globalized, companies large and small will encounter infectious diseases of both the epidemic and endemic varieties. in the latter case, it may well be in business's interest to work with local and global health officials to improve local infrastructures, such as hospitals and health services, not only as a means to generate goodwill and promote good corporate citizenship, but also as a way to help create a more hospitable operational environment. for example, the state-run china national offshore oil corporation donated million renminbi (just over us$ million) to aid research on sars. one of the most widespread and publicized epidemics today is hiv/aids. while the disease may be well publicized, its connection with the business community is not often elaborated upon. in fact, otherwise innocuous actions on the part of businesses have a hand in spreading the disease. for instance, truckers working for long-distance transportation companies have been identified as a major transmitter of the disease throughout africa and asia. hiv/aids also has devastating effects on businesses themselves. barclay's bank of zambia, for example, reported losing more than a quarter of its senior managers to the disease. a mattress company in zimbabwe hires and trains three people for every position due to attrition by the disease (forstater et al., ) . aids has become south africa's biggest single killer. in a south africa's medical research council calculated that percent of the deaths of those aged between and in the previous year were due to the aids pandemic. in recognition of the impact hiv/aids is having on its work force, daimlerchrysler south africa has, since , provided funding for standardized treatment for hiv-related diseases and anti-retroviral medication for its employees (daimlerchrysler, ) . according to the african vice president of the world bank, callisto madavo, hiv is the single greatest threat to future economic development in africa. of equal concern though is the growth rate of aids in asia. aids is growing fastest in asia leading many health experts to believe that it may overtake africa in the number of people infected with hiv. this will create a vexing problem for investors in europe and north america as their economies peak and they increasingly turn to the third world for profits. inexpensive labor is appealing but what if you cannot find employees to complete an order (jeter, ) ? the above discussion seeks not to provide a chronological listing of infectious diseases, but to highlight the dangers the world continues to face. businesses, indeed the world community, cannot afford to be complacent in the efficacy of modern medicine and assume that sars is an anomaly. infectious diseases are a fact of life and will continue to impact human society in the future. it is imperative that businesses develop coherent strategies to deal with such diseases when necessary. there should be no excuse for being "caught off-guard". the following section will look at specific impacts of the sars epidemic on commerce and present suggestions for organizations to protect themselves against similar future spread epidemics. in this section a distinction is made between the impact on large and small organizations. suggestions for contingency planning in face of epidemics so far we have attempted to provide a comprehensive discussion of how infectious diseases can gravely impact a firm's ability to function smoothly, unless adequate contingency planning is incorporated into its strategic management function and crisis management plan. in this section, we attempt to provide suggestions to minimize the impact of operating in an emerging market where contagious diseases are a reality. there are several areas that a contingency plan should address, in order to deal with the kind of epidemics that we have recently witnessed. further work will be needed to more fully develop the precise parameters of these dimensions, but for our purposes, we offer below some of the key areas that we feel a contingency plan should seek to address. businesses will need to re-examine the level of inventory, so as to provide some level of buffer in case of emergency. certainly we recognize that this adds to the cost of doing business, but we suggest that operationally this merely represents an additional variable in modeling the optimal level of inventory necessary. furthermore, businesses will need to assess whether it is practicable to secure their supplies from more than one source. diversification, as we know, spreads the risk. as much as possible, we need to incorporate technology into our operations, and re-evaluate location attractiveness with an eye towards the ease of technology replication as well as emergency backups. when opportunities arise move employees around global locations. these moves can be for short stints. the objective is to share understanding of competitive advantage. this may help upper management in reestablishing their competitive advantage in an alternative location. it is also important that values central to the business be ingrained in the workers to the extent possible. in this instance, continual efforts of re-education may be a useful step to take. we posit that companies would be concerned about how its workers are affected by the epidemic in terms of health, safety, and even emotion. as major epidemics such as sars could not be foreseen, it is imperative that managers take an emergent approach to plowing through the problem. companies in the many emerging markets where government regulations and transparency are lacking may particularly need to do more than simply adopt the official government line regarding the effects of the epidemic. to the extent possible, businesses should consider hiring local management talents as well as rotating key personnel to multiple locations of operations so as to build a solid base within the company from which local knowledge and expertise can be tapped. it is critical also that this knowledge is not only the exclusive domain of senior management, but that open communication be instituted throughout the company to enable workers at all level to know what is going on and what to expect. one of the unfortunate results of secrecy is that it often leads to unfounded rumors that only serve to aggravate a dangerous situation. corporations need to revisit their health plan to consider the need to establish health policies for suppliers. the "we didn't know" defense does not work too well any more in today's world of instant communication. businesses need to not only have in place their own health policies related to epidemics, but should determine whether their suppliers have adopted effective health policies to deal with such crises. regardless of all that we know, we acknowledge the impossibility of predicting future events. consequently, companies should not waste time and resources attempting to plan for patterns that are simply unpredictable. rather, it is critical that companies pay appropriate attention to contingency planning (such as crisis management plans); the basis of which are already well understood. what we have done is to tease out the important lessons from the sars epidemic. we have looked at its impact on organizations operating in emerging markets and drawn suggestions from this event. crisis management plans must be robust enough to handle all forms of the unexpected. as events arise that give us insight into the unforeseen, it is essential that organizations reexamine their crisis management plans to see if they were designed effectively enough to handle the unique features of our evolving environment. for those organizations that have operated without a crisis management plan, sars is a reminder of the importance of designing such a plan. the sars epidemic also shows how a crisis management plan must be integrally connected with an organization's strategic planning, thus being emergent rather than static in structure. it would be informative to take stock of what has transpired since the outbreak of the sars epidemic. a year after the disease first broke, it would be of intellectual (and practical) interest to assess what, if anything, the business community has put in place to combat such medical challenges. furthermore, inasmuch as we have offered some useful suggestions in this paper to deal with similar crises, we believe the exercise would be well served by couching our recommendations in a framework based in theory. such a future study should reveal whether the business community has adopted any important lessons that might be learned from the sars outbreak, and render our proposed contingency planning recommendations more practical in light of actual corporate actions. encephalitis outbreak in mainland china statistics are first casualty flu pandemic hit insurers hard emerging markets and international development: options for us foreign policy china isn't the only alluring partner for investors: despite worries, southeast asia still draws firms doing business in emerging markets: entry and negotiation strategies exercise in terror municipal affairs minister david young says he hopes ottawa will 'rethink' its compensation offer for the province's sars outbreak how congress coped in the age of yellow fever emerging markets of the global marketplace the sars outbreak: cases flare in taiwan; china gets draconian sales take a holiday airline woes: sars take toll on cara masked peril europe struggles to eradicate avian flu outbreak five rules for winning emerging market consumers before disaster hits: a multifaceted approach to crisis management emerging markets: a practical guide for corporations, lenders, and investors infomart ( ), available at: www.infomart.ca/doss/doss_db_display.php?key ¼ corp/cfps international bank for reconstruction and development/the world bank aids plants crop of death in africa many us firms fear sars will hurt profits this quarter beijing imposes new sars curbs: city's theaters and cafés are shut down as china lists another cases epidemic disease since the black death hong kong worries about bill to curb sars reporting china's growth may fall below percent: sars causes drop in sales of electronic products, closing of stock exchanges crisis management: a diagnostic guide for improving your organization's crisis preparedness sars squeezes asia's travel sector: industry study says virus may cost economies billions of dollars, millions of jobs emerging markets and international development: options for us foreign policy infection rates might drop as spring temperatures rise the high cost of illness nokia warns of lower sales, blaming economy and sars the big emerging markets: outlook and sourcebook local health official continue to plan for crisis cumulative number of reported probable cases of sars china cool toward md who told sars truth: whistleblower treated both as a hero and political threat, writes geoffrey york in beijing key: cord- - imi v authors: tang, a. c. y.; kwong, e. w. y.; chen, l.; cheng, w. l. s. title: associations between demographic characteristics, perceived threat, perceived stress, coping responses and adherence to covid- prevention measures among healthcare students in china: a cross-sectional survey with implications for the control of covid- date: - - journal: nan doi: . / . . . sha: doc_id: cord_uid: imi v objectives: to investigate the associations between demographic characteristics, perceived threat, perceived stress, coping responses and adherence to covid- prevention measures in chinese healthcare students. design: a cross-sectional survey collecting data in hong kong and fujian province of china. self-administered questionnaires were collected via online platform in april . participants: a convenience and snowball sample of students aged years or older and studying a healthcare programme in hong kong or fujian. setting: students were recruited in tertiary education institutions/universities in hong kong and putian (a prefecture-level city in eastern fujian province). the institutions offered various healthcare programmes in degree or sub-degree levels. main outcome measures: compliances to social distancing and personal hygiene measures were assessed by -item social distancing scale and -item personal hygiene scale respectively. path analysis was performed to identify factors associated with the compliance outcomes. results: the participants reported high compliances to both social distancing and personal hygiene measures. confidence to manage the current situation, wishful thinking and empathetic responding directly predicted compliance to social distancing ({beta}=- . , p< . ; {beta}= . , p= . ; {beta}= . , p< . respectively) and personal hygiene measures ({beta}=- . , p< . ; {beta}= . , p< . ; {beta}= . , p< . respectively). gender, geographical location, and clinical experience were the only three demographic variables having direct and/or indirect effects on social distancing and personal hygiene measures. the final model constructed demonstrated a very good fit to the data (chi-square x = . , df= , p= . ; x /df= . ; gfi= . , cfi= . , tli= . , rmsea= . ). conclusions: the predictive model constructed in this study is the first one to explore factors associating with the compliance to infection control measures in healthcare students amid the covid- outbreak. the findings suggest that students who are male, habituate in hong kong, have more clinical experience and weak confidence to manage the threat tend to have lower compliance to social distancing and personal hygiene measures. wishful thinking, contrasting to previous studies, was first found to positively associate with adherence to covid- control measures. since china first identified and reported a pneumonia case in wuhan to the world health organization (who) country office on december , covid- has infected over million people in more than countries, resulting in , deaths as of june . the extent of community spread of covid- is significantly greater than that for previous viral outbreaks such as severe acute respiratory syndrome (sars) in , h n influenza in , and middle east respiratory syndrome (mers) in and . the highly contagious nature of covid- , even during the incubation period, favours the insidious and rapid transmission of sars-cov- (the virus responsible for the covid- outbreak) from person to person via respiratory droplets and contact, as asymptomatic people are unaware of being infected. [ ] [ ] [ ] in efforts to swiftly control the continuous spread of the virus, many countries have been launching a series of stringent infection prevention and control measures (icps), such as mandatory quarantine, massive lockdowns, border control, and suspending schooling to seal off transmission. however, these aggressive icps have unprecedentedly restricted daily living and hampered global economic activities. reports warn that the covid- pandemic will shrink global gdp by almost one percent in , hitting people's livelihoods hard due to the resulting depression of the employment market. , to mitigate the socioeconomic impact of the pandemic, governments have been gradually resuming normal social and economic activities along with less restrictive but essential icps to control the spread of the virus. rationale of the proposed study at present, implementing essential icps is the sole approach to mitigate virus spread in the community. who and national health agencies have compiled a recommended list of covid- icps for the general public to follow, including social distancing, avoiding crowds, wearing face coverings, handwashing with soap and water or using hand sanitizer with at least % alcohol, and regular cleaning and disinfection of touched surfaces. , , reports related to numerous community cluster infections have indicated the importance of strict compliance with the recommended icps to minimise viral transmission. for instance, the nightclub cluster in south korea, which was initiated by a man visiting several nightclubs without wearing a mask, led to a resurgence of new infections in south korea. understanding the underlying factors that determine people's compliance with icps in a community setting is therefore a pressing need. evidence regarding compliance with icps in the context of the covid- pandemic is currently underreported. with reference to previous studies concerning factors related to icp adherence during the earlier sars and h n outbreaks, notable regional and demographic differences were observed in the adherence to the icps by the general public. [ ] [ ] [ ] [ ] [ ] [ ] older, more educated females are generally reported as having higher compliance with the icps. , - moreover, higher icp compliance is also associated with those who have a higher anxiety level, higher perceived risk of infection, better knowledge about the infection, and belief in the effectiveness of the recommended icps. , - greater trust in authorities has also been found to favour engaging in icps. this study targeted healthcare students, a group that is currently under-investigated regarding their compliance with icps. relevant studies have often targeted healthcare workers during virus outbreaks. [ ] [ ] [ ] [ ] [ ] according to the scanty evidence available, healthcare students were not as knowledgeable and competent as their seniors regarding icps. even medical students' significant improvement in hand hygiene practice after experiencing sars was still considered insufficient. in contrast, nursing students were found to exercise moderate compliance with universal precautionary measures when they possessed sufficient knowledge about infection control precautions. when healthcare students participate in internship/practicum in hospitals/clinics, insufficient compliance with icps on their part may facilitate viral spread from community to hospital, or vice versa. therefore, the present study aims to investigate the determining factors associated with compliance with covid- icps by healthcare students to fill in gaps in the existing body of knowledge and help stakeholders devise effective public health interventions to enhance healthcare students' compliance with icps. for the purpose of understanding adherence to covid- icps, a hypothesised health behaviour model was formulated based on the health belief model and transactional model of stress and coping to explain the associations among potential contributing factors and compliance with icps during the covid- pandemic (figure ). engaging in behaviours that promote health (i.e. covid- icp behaviour) is influenced by the perceived threat of covid- , such as the chance of becoming infected, the prognosis, and the perceived stress level, which is affected by the degree of perceived threat. an increase in the stress level will bring about an evaluation of coping responses to overcome the stress, which will eventually provoke a series of health behaviours to cope with stress. for the general public, specifically, who and national health agencies have recommended social distancing and personal hygiene measures to prevent covid- transmission in the community. examples of social distancing are avoiding crowded places and refraining from shaking hands, while measures related to personal hygiene measures include wearing a mask and handwashing with hand sanitizer. for the coping response in this study, we chose wishful thinking and empathetic responding, which were found to be commonly adopted by individuals during outbreaks of sars and west nile virus. , wishful thinking is a type of emotion-focused coping response that refers to an individual's effort to cognitively escape from or avoid a situation by simply fantasising or hoping the situation will go away or will somehow be over. evidence has shown that wishful thinking is often associated with negative health outcomes such as poor adjustment to illness. empathetic responding is a relationship-focused coping response in which the individual attempts to understand what others are experiencing and makes an effort to offer support and assistance. lee-baggley et al. found wishful thinking was positively associated with avoidant health behaviours such as eschewing public areas and people during a sars outbreak. conversely, empathetic responding was associated with proactive prevention behaviours such as mask wearing and exerting caution in personal hygiene. , the previous literature has suggested that demographic characteristics play a significant role in people's health behaviours. consequently, demographic characteristics were included in the hypothesised model as they were believed to indirectly influence engagement in icps through perceived threat, perceived stress, and coping responses. path analysis was adopted to verify the hypothesised associations among the studied variables in this model. the objective of this study was to investigate the associations between demographic characteristics, perceived threat, perceived stress, coping responses, and adherence to covid- icps in chinese healthcare students using path analysis. the main hypothesis was that demographic characteristics, perceived threat, perceived stress, and coping responses associate with social distancing and personal hygiene measures. we conducted a cross-sectional study, collecting data in hong kong and fujian in china. in hong kong, the samples included students from two universities and one tertiary education institution. students from three tertiary education institutions in putian, a prefecture-level city in eastern fujian province, were also a part of the study. these universities/tertiary education institutions offer various healthcare programmes at degree or sub-degree levels such as nursing, chinese medicine, physiotherapy, and occupational therapy. students undertaking these programmes must take taught courses and undergo clinical practicums in hospital and community settings. practicum hours vary among programmes. eligible students were recruited via online platforms in april . participants completed selfadministered online questionnaires that collected data on demographic characteristics, perceived threat, perceived stress level, use of wishful thinking, and empathetic responding and adherence to social distancing and personal hygiene measures in response to covid- . completing the entire questionnaire required about minutes. the participants were informed of the objectives and . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. (which was not certified by peer review) the copyright holder for this preprint this version posted july , . . https://doi.org/ . / . . . doi: medrxiv preprint procedures of the study and their rights of participation before beginning the survey. returning the completed questionnaire implied consent to participate in the study. the manuscript was written according to the strobe guideline for observational studies. participants eligibility criteria included fulltime students aged years or older and engaged in one of the healthcare programmes offered in the universities or the tertiary education institutions for this study. such programmes included general/obstetric nursing, medical laboratory science, chinese medicine, radiation therapy, pharmacy, occupational therapy, and physiotherapy. students were ineligible if they were studying in a programme other than those listed. mass emails were sent to the students via school emails to invite them and their friends to complete the online questionnaire. total participants numbered , , and the number of parameters to be estimated in the predictive model was . this sample size was adequate for modelling, in which the ratio of sample size to estimated parameters should be : . outcome measures compliance with social distancing and personal hygiene measures our main outcome of interest was adherence to covid- icps, comprising social distancing (sod) and personal hygiene measures (phm). the scales for measuring sod and phm were developed based on the who's and centers for disease control and prevention's guidelines for preventing and controlling the spread of covid- for the public and individuals, , along with questionnaires developed by the sars collaborative research group in . sod was measured using ten items, including "avoided travel to covid- infected areas," "avoided eating in restaurants," and "avoided shaking hands." phm was measured by five items, such as "wearing a mask," "washing hands more often," and "using disinfectants." participants were directed to rate their likelihood of performing the actions described in the items to prevent covid- on a -point likert scale, where was "very unlikely," and was "very likely." the total sod score and phm score were the aggregation of the corresponding item scores. the higher the score was, the more likely the respondent was to engage in the corresponding measures. perceived threat (pt) was measured by four items extracted from the perceived threat scale originally used to measure an individual's perceived threat due to sars. the participants were asked to rate the extent to which four statements were true for them at the current moment on a -point likert scale, ranging from "not at all" ( ) to "a great extent" ( ) . item examples are "i feel nervous about getting covid- ," and "covid- is threatening my health." a summation of the items' scores formed the total pt score. the higher the score, the greater was the perceived threat to the individual. perceived stress (ps) was measured by the perceived stress scale (pss- ) developed by cohen and williamson. the pss- is a -item self-reported questionnaire that asks respondents to rate the frequency of their feelings and thoughts about life events and situations over the previous month using a -point scale ranging from ("never") to ("very often"). according to our results after confirmatory factor analysis (table ) , the pss- was divided into two subscales that measured stress level (ps ) and confidence about managing the current situation (ps ). ps was measured by six items, such as "in the last month, how often have you been upset because of something that happened unexpectedly?" and "in the last month, how often have you found that you could not cope with all the things that you had to do?" a higher score indicated greater stress. ps was measured by four items, including "in the last month, how often have you felt confident about your ability to handle your personal problems?" and "in the last month, how often have you felt that things were going your way?" ps was inversely scored, meaning that a higher total ps score indicated lower confidence about handling the current situation. . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted july , . . https://doi.org/ . / . . . doi: medrxiv preprint wishful thinking (wt) and empathetic responding (er) were measured by two items taken from the wishful thinking subscale of the ways of coping questionnaire and six items taken from the relationship-focused coping scale, respectively. participants rated the items from the two scales on a point likert scale, ranging from "not at all" ( ) to "a great deal" ( ) to indicate the extent to which they had managed their concerns or fears about covid- through wishing or helping others. the two items for measuring wt were "wishing covid- would go away or somehow be over with" and "hoped a miracle would happen." examples of items measuring er included "tried to understand the other person's concerns about covid- ," "tried to understand how the other person felt about covid- ," and "tried to help the other person(s) by listening to their concerns about sars." higher total scores for the scales indicated a greater likelihood of using wishing and helping others to manage stress. demographic variables described characteristics of the students and their programme of study. age, gender, year of study, and clinical experience were variables collected for student characteristics. programme characteristics included geographical location of the institution, academic level of the programme, and professions. age was measured on a continuous scale, while the other variables were measured via categories. all scales and demographic information were translated into chinese for collecting the data in putian. they were first translated into chinese by a research team member and backward translated by a nurse educator. a dentist who is a native english speaker confirmed that the two versions of the scales contained the same meaning. the chinese scales were then validated by five experts in nursing education, psychology, infection control, epidemiology, and public health nursing. the content validity of all scales ranged from very good to satisfactory (cvi = . - ). table provides a summary of the scales included together with their psychometric properties. psychometric analyses were conducted for each scale used in this study. first, confirmatory factor analysis was performed to assess the underlying structure of each scale. internal consistency (cronbach's alpha) was calculated for each scale and its potential factors. in summary, our psychometric testing indicated that the study scales had good internal consistency, interpretability, and adequate factor structure. as a result, the scales were considered reliable, valid measures of the variables in the study. statistical analysis amos was used to conduct analyses. for all tests, we used -sided p-values with alpha <= . as the level of significance. we estimated the mean and standard deviation or frequency and percentage of the study variables. missing values, normality, and outliers were first checked prior to the main analysis. no missing values nor outliers were found in the dataset. the dataset did not deviate from multivariate normality, as the mardia value obtained was lower than the mardia's coefficient cutoff of with observed variables. for the main analysis, we ran a path analysis to explore the associations between covariates and outcomes. maximum likelihood (ml) was used to estimate the regression coefficient of each path presented in the model. the model was trimmed until all insignificant paths were eliminated. path coefficients were computed, including standardised and unstandardised regression coefficients with a % confidence interval. the model fit was determined by fit indices that included goodness-of-fit index (gfi) > . , comparative fit index (cfi) and tucker-lewis index (tli) >= . , , root mean square error of approximation (rmsea) < . , and relative chi-square (x /df) < . subgroup analyses were conducted for geographical location, gender, professions, and clinical experience, as the former two demographic variables were reported to have a significant impact on health behaviours, while the latter two might affect a person's knowledge about the infection. , - a . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted july , . . chi-square test was performed to examine the difference of categorical socio-demographic variables between region, gender, professions, and clinical experience, while an independent t-test or one-way anova test with tukey post hoc test was employed for the continuous independent variables and the outcomes. socio-demographic characteristics responses from a total of , students from healthcare professions were analysed. most participants were from fujian. the average age was . (sd= . ). out of the total number, . % were female. about half were pursuing an associate degree, and . % were studying for a bachelor's degree, with around % studying nursing. about % of the participants were year or year students. more than % did not have clinical experience. in general, the pt scores of the students averaged . (sd= . ), while their mean ps and mean ps scores were . (sd= . ) and . (sd= . ), respectively. regarding the coping responses, the mean wt score was . (sd= . ), and the mean er score was . (sd= . ). the mean sod score was . (sd= . ) , and that for phm was . (sd= . ). the mean scores for pt, ps , and ps were around the midpoint of the corresponding score ranges, indicating that the participants felt moderate threat and stress regarding covid- and had moderate confidence about their ability to manage the situation. the mean scores for both wishful thinking and empathetic responding were on the high side of the corresponding score ranges, indicating that the respondents often used wishful thinking and empathetic responding to manage their stress. the participants revealed high compliance with sod and phm, as the high mean sod and phm scores reflected. table outlines the descriptive findings of the study. the hypothesised model with all paths were tested first. gradually, all non-significant paths were dropped until only significant paths remained. figure depicts the final predictive model with significant pathways and correlations. the trimmed path model shows good fit indexes, with chi-square x = . , df= , p= . ; x /df= . ; gfi= . , cfi= . , tli= . , rmsea= . . table presents path coefficients with their standard errors and their significant levels for the model. the variables, which had significant direct and/or indirect effects on sod and phm, included gender, geographical location, clinical experience, perceived threat, perceived stress, and coping responses. ps , ps , wt, and er were significantly associated with sod. among them, ps , wt, and er displayed the greatest contributions to sod, with unstandardised regression coefficients (β) of - . ( %ci=- . to - . , p< . ), . ( %ci= . to . , p= . ), and . ( %ci= . to . , p< . ), respectively. fujian students had a higher mean sod score than those in hong kong by . scores ( %ci= . to . ). this result indicates that compared to hong kong students, fujian students were more willing to engage in social distancing. female students showed higher compliance with sod than their male counterparts, with β of . ( %ci= . to . , p= . ). those having clinical experience had a lower mean sod score than those without (β =- . , %ci=- . to - . , p< . ). these results imply that students with clinical experience are less likely to avoid going to public places than students without such experience. similar to sod, ps (β=- . , %ci=- . to - . , p< . ), wt (β= . , %ci= . to . , p< . ), and er (β= . , %ci= . to . , p< . ) were the three variables with the greatest contributions towards phm, though they exhibited lesser effects compared to those on sod. ps exerted an indirect impact on phm through wt and er. gender was the only significant demographic variable that had a direct impact on phm (β= . , %ci= . to . , p< . ), in that female students were more likely to comply with personal hygiene measures than male students. the negative associations of ps with sod and phm indicate that a high level of confidence about managing the current situation . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted july , . . https://doi.org/ . / . . . doi: medrxiv preprint increased compliance with sod and phm. unlike the hypothesised model, pt did not have a direct impact on both sod and phm but infiltrated its impact into the two outcomes by way of ps and er. the three demographic variables and ps exhibited their indirect influences on sod and phm through other variables in addition to their direct effects. geographical location was positively associated with pt and er, with β of - . ( %ci=- . to - . , p< . ) and . ( %ci= . to . , p< . ), respectively. this result means that fujian students perceived less threat and adopted more empathetic responding than hong kong students. gender positively associated with pt (β= . , %ci= . to . , p= . ), ps (β= . , %ci= . to . , p= . ), and wt (β= . , %ci= . to . , p< . ). students having clinical experience had a higher pt score than those without (β=- . , %ci=- . to - . , p< . ), indicating that students with clinical experience tended to feel more threat than those without. students with higher confidence towards managing the current situation drew on wishful thinking and empathetic responding to cope with the situation as reflected in the significant negative association between ps and wt (β=- . , %ci=- . to - . , p< . ), and between ps and er (β=- . , %ci=- . to - . , p< . ). the hong kong students exhibited significantly higher pt (p< . ) and ps scores (p< . ) but a lower ps score (p< . ) than their fujian counterparts. the fujian students had a significantly higher er score and were more likely to comply with sod and phm than the hong kong students ( table ) . female students had a lower pt score and higher ps , wt, sod, and phm scores in comparison to male students (table ). students with no clinical experience revealed significantly lower pt and ps scores than those with clinical experience (p< . ). participants without clinical experience were found to practise higher compliance with sod compared to the other two groups (p< . ) ( table ) . physiotherapy students had the highest pt score, followed by occupational therapy students. the same pattern was observed for ps , though it is not statistically significant (table ). in summary, fujian female students, irrespective of profession, showed greater compliance with sod and phm. students with no clinical experience adhered more to sod compared to those having clinical experience. in this study, the use of path analysis to construct the predictive model revealed the direct and indirect contributions of demographic and independent variables to compliance with social distancing and personal hygiene measures. the final predictive model for covid- icps demonstrates that the significant demographic variables (i.e. gender, geographical location, clinical experience) and stress level do not merely contribute to social distancing and personal hygiene measures directly but also impose indirect effects on them through other studied variables in the model. perceived threat, as expected, does not have a direct effect on compliance with covid- icps. wishful thinking and empathetic responding directly and positively contribute to the two outcomes. demographic characteristics the significant associations of gender and geographical location with infection control measures reported in this study were similar to those in previous studies in which females showed greater compliance with infection control measures such as handwashing than males among college students and healthcare workers. , [ ] [ ] [ ] healthcare workers in different countries were reported to have varying adherence to personal protection measures. [ ] [ ] [ ] the contributions of the present study are twofold. first, the negative association between clinical experience and compliance with social distancing suggests that healthcare students with clinical experience comply less with social distancing. second, geographical location and clinical experience directly and positively associate with compliance with social distancing only, though not personal hygiene measures. the higher compliance with social distancing found in fujian students might be the result of a difference in regulations regarding social distancing between . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted july , . . https://doi.org/ . / . . . doi: medrxiv preprint hong kong and fujian. restrictive measures were launched at an early stage of the covid- outbreak in fujian. as a consequence, the fujian government imposed the strictest measures to control social contact among people, such as banning social gatherings and suspending public transportation. in contrast to fujian, the regulations affecting social distancing in hong kong have been less restrictive at that time. for instance, in hong kong, people could have gatherings, though these were limited to four attendees at most. public transport was still in operation, but passengers were required to put on facemasks. in addition, students and workers in mainland china are used to travelling across cities and provinces seeking better study and job opportunities. residents of fujian may thus be more vigilant about the potential for infection caused by contact in public areas with strangers from high-risk cities. regarding the negative association of clinical experience and compliance with social distancing, we should interpret it with caution, as students with clinical experience were mainly clustered in the hong kong samples. as hong kong students were found to have significantly lower compliance with social distancing than the fujian students in the subgroup analysis, the negative association of clinical experience with compliance in social distancing might be biased by the skewed samples. further studies shall be launched to confirm this association. perceived stress pss- is a widely used scale to assess the perception of stress in response to life events in an adult population. unlike previous studies that commonly used the total scale score for analysis, we split the scale into two domains -stress level (ps ) and confidence about managing the present situation (ps )when performing the path analysis. the present model suggests that confidence about managing the situation has a stronger predictive effect than one's stress level for both social distancing and personal hygiene measures. confidence about managing an encountered difficulty relates to one's sense of selfefficacy. this sense is a major behaviour-specific cognitive factor contributing to engagement in behaviour that promotes health. a high level of self-efficacy can reduce the perception of barriers, improving the likelihood of engaging in healthful practices. public health interventions may focus on enhancing people's self-efficacy to increase adherence to icps for covid- . coping responses wishful thinking and empathetic responding were both found to positively associate with social distancing and personal hygiene measures, results that are incongruent with those from previous studies regarding sars and other epidemics. , in this study, wishful thinking and empathetic responding both directly and positively contributed to adherence to social distancing and personal hygiene measures. conversely, lee-baggley et al. reported that wishful thinking did not relate to personal hygiene measures in sars samples. the distinctive nature of covid- may explain the incongruent findings between previous studies and ours. the transmissibility of covid- is much higher than that for viruses encountered in previous incidents. the progress of the current virus is fluctuating, and no medications are available at this time to cure the infection. people are in fact facing many unknowns and uncertainties that exert a significant impact on their psychological wellbeing. recent studies have reported that covid- has compromised the psychological wellbeing of healthcare workers and the general public. [ ] [ ] [ ] people suffering from despair may turn to wishful thinking to relieve their psychological burdens in an attempt to preserve their mental health. although the literature often associates wishful thinking with higher stress level and poorer health outcomes, , , the use of wishful thinking in the face of the covid- pandemic may have a protective effect on people's mental wellbeing. the positive correlation between wishful thinking and empathetic responding may support the protective effect of wishful thinking on the participants' mental health in that greater employment of wishful thinking would simultaneously increase the use of a proactive stress-coping strategyempathetic responding to manage the stress. in addition, the participants with more confidence about managing the threat practise more wishful thinking as reflected by the negative association between ps and this type of mental focus. . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted july , . . https://doi.org/ . / . . . doi: medrxiv preprint the present study showed that empathetic responding had a greater influence on social distancing than on personal hygiene measures, as the unstandardised regression coefficients of the corresponding paths in the model reflected. conversely, previous studies found that empathetic responding had a higher association with personal hygiene measures in sars and west nile virus samples. , the different findings among studies may be explained by the differences in the key strategies to control viral spread in different outbreaks. in covid- , social distancing is a key strategy to mitigate community spread of the infection, along with personal hygiene measures. however, in the case of sars, personal hygiene measures were emphasised to quell the outbreak. empathetic responding thereby relates to key specific public health strategies to control the corresponding outbreaks. another possible explanation for the incongruence may involve the sample characteristics in the present study. in our samples, over percent of the participants were from fujian. this number is significant because the fujian group was found to have a significantly higher mean empathetic responding score than the hong kong group in subgroup analysis. the greater use of empathetic responding observed in the fujian group may be attributable to the social norm to maintain close relationships within neighbourhoods and support each other in mainland china. although public health measures to control covid- have forced the participants to isolate themselves from others with whom they used to be in close contact, they may continue to interact as usual through other means such as communication apps or social media to share their stress and difficulties. further, the mainland students are accustomed to leaving their hometowns to seek better study opportunities in more prosperous cities. because some of the students were forced to stay in hostels during the outbreak because of the lockdown and suspension of transportation, they may exhibit empathetic behaviours to support each other to transcend a difficult situation. this study is the first to use path analysis to explore factors associated with compliance with infection control measures for the control of covid- among healthcare students. both direct and indirect effects of potential factors contributing to compliance with covid- icps were revealed. this approach is more advantageous than regression analysis in the sense that any indirect effects of the factors would not be masked in path analysis. the statistically significant paths and the good fit of the model provide empirical support for the study hypotheses. stakeholders may refer to the present model to provide interventions targeted not only at factors directly associated with social distancing and personal hygiene measures but also factors associated with confidence in managing the situation and coping responses that can improve compliance. although this study contributes to the knowledge of factors associated with compliance with covid- icps, several limitations may limit the validity of the findings. first, the convenience and snowball samples may not reflect the full characteristics of the entire population. for instance, the participants were mainly from junior years, and only a few senior students who would have more clinical experience were included. thus, the negative association found between clinical experience and compliance with social distancing may be biased because the samples were dominated by junior students. second, since the data collection was conducted in china, the predictive model may not apply to other countries with different socio-cultural backgrounds and dissimilar implementation policies for covid- icps. third, a self-reported survey was used to collect students' perceptions and likelihood to comply with covid- icps. thus, the data may be subject to social response bias. fourth, the present model was established based on cross-sectional data, making it difficult to draw causal inferences about the relationships between variables. a world-wide study should be designed to collect subjects from more countries to enhance study validity. also, the use of random sampling and inclusion of more objective data collection methods should be considered to minimise biases caused by unbalanced sample characteristics and subjective responses. further research should additionally examine the causal relationships using longitudinal methodologies. . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted july , . . https://doi.org/ . / . . . doi: medrxiv preprint the predictive model developed in this study is the first to explore factors associated with compliance with infection control measures by healthcare students amid the covid- outbreak. the findings help stakeholders to identify students at risk for poor compliance. the findings suggest that students who are male, reside in hong kong, have more clinical experience, and exhibit weak confidence about managing the threat tend to display lower compliance in terms of social distancing and personal hygiene measures. wishful thinking, which has been generally connected to negative health outcomes, was found to be a positive factor in complying with infection control measures for covid- . public health interventions should target groups susceptible to poor compliance to strengthen the control of covid- spread. . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted july , . . . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted july , . . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted july , . . . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. (which was not certified by peer review) the copyright holder for this preprint this version posted july , . . . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. (which was not certified by peer review) the copyright holder for this preprint this version posted july , . . https://doi.org/ . / . . . doi: medrxiv preprint . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. (which was not certified by peer review) the copyright holder for this preprint this version posted july , . . is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted july , . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. (which was not certified by peer review) the copyright holder for this preprint this version posted july , . . world health organization. who coronavirus disease (covid- ) dashboard special expert group for control of the epidemic of novel coronavirus pneumonia of the chinese preventive medicine. an update on the epidemiological characteristics of novel coronavirus pneumonia (covid- ) centers for disease control and prevention. how covid- spreads world health organization. coronavirus disease (covid- ) advice for the public covid- likely to shrink global gdp by almost one percent in coronavirus kills . million us jobs in april in historic collapse factors associated with critical-care healthcare workers' adherence to recommended barrier precautions during the toronto severe acute respiratory syndrome outbreak protecting health care workers from sars and other respiratory pathogens: organizational and individual factors that affect adherence to infection control guidelines differences in the compliance with hospital infection control practices during the influenza h n pandemic in three countries factors affecting healthcare workers' compliance with social and behavioural infection control measures during emerging infectious disease outbreaks: rapid evidence review. medrxiv hand hygiene among physicians: performance, beliefs, perceptions jordanian nursing students' knowledge of, attitudes towards and compliance with infection control precautions the health belief model: a decade later stress: appraisal and coping coping with the threat of severe acute respiratory syndrome: role of threat appraisals and coping responses in health behaviors coping and health behaviors in times of global health crises: lessons from sars and west nile the association of coping to physical and psychological health outcomes: a meta-analytic review strengthening the reporting of observational studies in epidemiology principles and practice of structural equation modeling perceived stress in a probability sample of the united states the relationship between coping and emotion: implications for theory and research the interactional context of problem-, emotion-, and relationship-focused coping: the role of the big five personality factors gender and ethnic differences in hand hygiene practices among college students the impact of a health campaign on hand hygiene and upper respiratory illness among college students living in residence halls infection prevention and control compliance in tanzanian outpatient facilities: a cross-sectional study with implications for the control for the control of covid- . the lancet global health differences in the compliance with hospital infection control practices during the influenza h n pandemic in three countries avian influenza and south jakarta primary healthcare workers: a controlled mixed-method study primary care physicians in hong kong and canada -how did their practices differ during the sars epidemic? self-efficacy mechanism in human agency the health belief model: a decade later factors associated with mental health outcomes among health care workers exposed to coronavirus disease psychological stress among health care professionals during the novel coronavirus disease outbreak: cases from online consulting customers. intensive and critical care nursing awareness, risk perception, and stress during the covid- pandemic in communities of tamil nadu, india. psyarxiv anxiety, perceived stress and coping strategies in nursing students: a cross-sectional correlational descriptive study mental well-being, and coping strategies during stress for preclinical medical students in vietnam relationship between mental health of nursing students and coping, self-esteem and social support key: cord- -tx m gu authors: wan, kin-man; ka-ki ho, lawrence; wm wong, natalie; chiu, andy title: fighting covid- in hong kong: the effects of community and social mobilization date: - - journal: world dev doi: . /j.worlddev. . sha: doc_id: cord_uid: tx m gu the globalized world economy has been affected by the covid- pandemic since early february . in the midst of this global public health crisis, a prompt review of the counterinsurgencies that have occurred in different jurisdictions is helpful. this article examines the experience of hong kong (hksar), which successfully limited its number of confirmed cases to approximately until early june . considering the limited actions that the government has taken against the pandemic, we emphasize the prominent role of hong kong’s civil society through highlighting the strong and spontaneous mobilization of its local communities originating from their experiences during the sars outbreak in and the social unrest in , as well as their doubts regarding the pandemic assessments and recommendations of the hksar and who authorities. this article suggests that the influence of civil society should not be overlooked in the context of pandemic management. ( words) its number of confirmed cases to approximately until mid-june . considering the limited actions that the government has taken against the pandemic, (wang, ng, and brook ) . however, it is worth studying the roles of public personnel in the covid- situation and the ways in which society responds to this pandemic. in this article, we examine the experience of the hong kong special administrative region (hksar) to explain the importance of civil society and social mobilization as decisive elements of the fight against the pandemic. in the time between the outbreak of covid- in mainland china during the month of january to mid-june, there have been approximately confirmed cases of the virus in hong kong, which is densely populated with over million people ( fig. ) . in addition to the government's efforts to limit the spread of the virus, the role of civil society is prominent to combat the surge of infection. paradoxically, the strong and spontaneous mobilization observed in hong kong was a consequence of the population's devastating memories of the sars outbreak in and the social unrest in , as well as of their skepticism of the pandemic figures, assessments and recommendations given by the authorities of hksar, mainland china, and the world health organization (who). the lesson that can be learned from hong kong is that of an alternative approach to ensuring the effectiveness of pandemic management. for details regarding the measures taken by the hksar government, please refer to appendix a. the advent of covid- (also known as sars by hku and the public) reminded the public of their experience during the sars outbreak in , which led to cases and deaths as well as economic depression in hong kong. as a result of this experience, the public learned the importance of social distancing, personal hygiene, and the use of surgical masks in the context of sars-like pandemics (lau et al., ) . among their asian neighbors, hong kong citizens were the first to react to the pandemic. using apple mobility trend data, fig. shows that hong kong citizens rapidly reduced their frequency of walking out of their homes by over % (from to approximately ) after the first reported case in hong kong on jan . this trend continued even during the lunar new year public holiday occurring days after. a survey also found that approximately . % respondents avoiding going to crowded places (cowling et at. ), which is highly consistent with the apple mobility trend data. driving data from apple also exhibits a similar trend as does the walking data. for these similar results using data drawn from the google community mobility report, please see appendix b. extant works have suggested the crucial role of the state in the context of a pandemic; however, its effectiveness is dependent on the public's perception of the legitimacy of the government (wallner, ; gibson, caldeira and spence, ) . initially, the public demand for preventive measures from the government was high, and these measures included a full closure of the border between hong kong and mainland china and a sustainable supply of surgical masks. however, the hksar government was reluctant to act proactively and thus exacerbated the tension and distrust that had already been deeply established during the anti-extradition bill movement of . indeed, the prominent dissatisfaction of hong kong citizens is accompanied by declining trust towards the government. in fig. , we can observe a dramatic decline in the government trust from june , when the anti-extradition bill movement began. in the early stages of the pandemic (january to march), the rate of support for the chief executive was also recorded below over , and less than % of the population trusted the government and were satisfied with the police force (hong kong public opinion research institute, d; ho, ). it was argued that this attitude towards the police force has become a major divide between the citizens of hong kong and the hksar government (chau and wan, ). these attitudes have led to considerable public doubts about the measures that the government has taken and the policies that it has implemented in response to covid- . for instance, the prevention and control of disease ordinance, which prohibits all public gatherings of more than eight people, is perceived as a double standard, as police officers cited the ordinance for crowd control purposes in march but the government permitted the reopening of amusement parks and the hong kong book fair in june. this gathering is a monthly event held to commemorate certain protesters being attacked by riot police at a metro station. over half ( %) of the people of hong kong believe that the social distancing rule is a means for political suppression rather than for fighting against the pandemic (hong kong public opinion research institute, a). the hksar government's reluctance to fully shut down its border and the deeply rooted distrust between society and the government have raised questions regarding the rationale and priorities behind the government's policy-making process. some believe that the government has placed national interest and pride over public safety and local interest, which resulted in the following actions and responses from society. district councilors from january to early february. over % of the district councilors held at least one sharing activity in january, and this number increased to % and % in early and late february, respectively. these mask distributions were prioritized to serve the disadvantaged and groups with a high level of exposure risk , as these groups are the most vulnerable to covid- (jordan, adab, and cheng ). it is argued that the pro-democratic councilors, as a proxy representing a higher level of government distrust, were the first to act. fig. shows that the density of mask sharing in these pro-democratic districts is considerably higher than that of the pro-beijing districts before march. this implies that the higher the distrust towards the government is in a district, the faster the response of this district was. in addition to ppe sharing, this distrust of the government also led to more progressive actions against government measures. in late january, the hospital authority employees alliance (hkea), a union formed by medical professionals, organized a strike to demand a complete border shutdown after the chief executive refused to shut down the high-speed railway to china and restricted incoming travelers from wubei. over % of the public consistently supported this strike, and the government eventually announced that it would be partially shutting down the high-speed railway to china in early february (hong kong public opinion research institute, a). thus, the strike of hkea prevented a potential large-scale outbreak caused by travelers from infected regions. furthermore, the public distrust and social unrest occurring since the summer of the pro-beijing councilors are much more resourceful than the pro-democratic (wong ) . we also provide more supportive evidence and placebo test in appendix, please refer to tables a to a , and shown how to test unqualified ppe, and taught how to make cloth masks and hand sanitizers at home. a real-time dashboard, which included details regarding the cases, high-risk areas, questionable pharmacies, etc. , was established far before the government official dashboard was established. these platforms provided publicfriendly access to covid- -related information; this was essential in the fight against covid- , since unequal access to information due to differences in socioeconomic status would impede the effectiveness of the society's response to this public health crisis (lin et al., ) . a social and community-based network formed by these self-help models has promoted the protection of the public, especially that of disadvantaged groups and high-risk workers. the fast and transparent circulation of information has enabled citizens to overcome the collective challenges that have faced them (putman ). an important discussion regarding successful pandemic management centers on governance capacity, including information transparency and timely responses to potential threats. taiwan and hong kong are identified as outstanding cases regarding the containment of the deadly covid- virus due to the low number of confirmed cases and deaths in these places. while taiwan's success was identified as a model of high governance capacity, this article presented hong kong's success as a case supported by civic society and social mobilization. existing studies have suggested that trust between society and the government is crucial in responding to epidemics (blair et al., ) , and it is possible that the public gained a higher approval of leadership and a higher sense of national unity during this crisis, as the "rally-round the flag" concept suggested (mueller ; baum ) . in this article, we demonstrated that public distrust of the government may not necessarily lead to a failure of pandemic control. in contrast, skepticism of ineffective policies and the presence of a strong civic society driven by state society tensions may contribute positively to pandemic management. the case of hong kong exhibits a sharp deviation from the mainstream discourse that places a dual emphasis on capacity and accountability in effective crisis management. however, it should be made clear that our findings should not be interpreted to undermine the important role of the state in pandemic management. we are rather suggesting that the influence of civil society should be taken into serious consideration in the context of public health crisis-related studies (eimer and lutz, ) . the constituent foundations of the rally-round-the-flag phenomenon public health and public trust: survey evidence from the ebola virus disease epidemic in liberia the relationships between democratic experience, adult health, and cause-specific mortality in countries between and : an observational analysis surgical mask partition reduces the risk of non-contact transmission in a golden syrian hamster model for coronavirus disease pour (tear) gas on fire? violent confrontations and anti-government backlash in hong kong the role of community-wide wearing of face mask for control of coronavirus disease (covid- ) epidemic due to sars-cov- most hongkongers unhappy with official covid- response, post poll shows impact assessment of non-pharmaceutical interventions against coronavirus disease and influenza in hong kong: an observational study the role of executive time horizons in state response to aids in africa developmental states, civil society, and public health: patent regulation for hiv/aids pharmaceuticals in india and brazil why do people accept public policies they oppose? testing legitimacy theory with a survey-based experiment legitimization & de-legitimization of police: in british colonial & chinese sar hong kong community health module popularity of chief executive people's trust in the hksar government people's satisfaction with the disciplinary force-hong kong police force covid- : risk factors for severe disease and death avoidance behaviors and negative psychological responses in the general population in the initial stage of the h n pandemic in hong kong hong kong's summer of uprising ethnic politics, risk, and policy-making: a cross-national statistical analysis of government responses to hiv/aids media use and communication inequalities in a public health emergency: a case study of - pandemic influenza a virus subtype h n presidential popularity from truman to johnson making democracy work: civic traditions in modern italy legitimacy and public policy: seeing beyond effectiveness, efficiency, and performance response to covid- in taiwan: big data analytics, new technology, and proactive testing the impact of regime type on health: does redistribution explain everything electoral politics in post- hong kong we declare there is no conflict of interest among the authors and their funding bodies conceptualization, methodology, data curation, visualization, writing -original draft. lawrence ka-ki ho: conceptualization, writing-original draft, writing-reviewing and editing. natalie w. m. wong: conceptualization, writing-original draft, writing-reviewing and editing writing-original draft, writing-reviewing and editing key: cord- -exmk gmu authors: chan, sophia s.c.; leung, doris y.p.; leung, angela y.m.; lam, cindy; hung, ivan; chu, daniel; chan, chi kuen; johnston, janice; liu, shao haei; liang, raymond; lam, tai hing; yuen, kwok yung title: a nurse-delivered brief health education intervention to improve pneumococcal vaccination rate among older patients with chronic diseases: a cluster randomized controlled trial date: - - journal: international journal of nursing studies doi: . /j.ijnurstu. . . sha: doc_id: cord_uid: exmk gmu abstract background the -valent pneumococcal polysaccharide vaccine is recommended for elders, especially those with chronic conditions. objective the aim of this study was to determine if an additional multi-component health education intervention increases the uptake rate of the pneumococcal vaccination among older patients with chronic diseases. methods a cluster randomized controlled trial was conducted from december to march . the clusters were the individual weeks within five hong kong outpatient clinics over a -week period. a sample of patients aged or above with chronic diseases was recruited. intervention group received a -min brief telephone education intervention before and a -min face-to-face intervention during scheduled medical appointments at the respective clinics. all subjects received standard care including health education leaflets and/or a video show at the clinics. pneumococcal vaccination rate and awareness of the vaccination at -month follow up were measured. results the vaccination rate was higher in the intervention group compared to the control group ( % vs %; relative risk= . , % ci= . – . ), but the two groups did not differ significantly in their awareness of the vaccination at -month follow up ( % vs %, relative risk= . , % ci= . – . ). discussion a nurse-delivered brief health education intervention was effective in increasing uptake of pneumococcal vaccination among older patients with chronic diseases. what is already known about this topic? pneumococcal vaccination has been recommended for elders by the hong kong sar government since october . pneumococcal vaccination is relatively new to people, especially in hong kong. no study on testing the use of health educational programmes to promote pneumococcal vaccination uptake in the asian countries. evaluation of a nurse-delivered health education intervention which aimed to improve pneumococcal vaccination rate among older patients with chronic diseases. the vaccination rate was higher in older patients who received a -min brief telephone education intervention and/or a -min face-to-face intervention than those only received standard care including health education leaflets and/or a video show at the clinics. the two groups did not differ significantly in their awareness of the vaccination at -month follow up. streptococcus pneumoniae causes invasive pneumococcal diseases (ipd) including septicaemia, meningitis and bacteraemic pneumonia in all age groups, especially in children, elders, and persons with chronic illnesses (centers for disease control and prevention, ) . the incidence rate of ipd in older people is triple of those aged - years, and they have the highest risk of death from ipd (robinson et al., ) . globally, ipd had caused . million deaths annually in (world health organization, . in developed countries, the annual incidence rates of ipd range from to per , with higher incidence rates in those aged years ( - per , ), whilst in hong kong the average annual incidence rate of ipd was . per , from to (center for health protection, ). the -valent pneumococcal polysaccharide vaccine (ppv) is recommended for elders, especially those with chronic conditions. ppv is efficacious in reducing the risk of systematic infection in institutionalized elders (hutchison et al., ) , and preventing mortality due to pneumonia (fisman et al., ; jackson et al., ; loeb, ) from observational studies, but its efficacy from randomized controlled trials in older patients with chronic diseases, is still unclear and subject of debate (moberley et al., ) . as pneumococcal infections become increasingly difficult to treat due to drug resistance, vaccination is an important and efficient way for preventing ipd due to s. pneumonia (spindler et al., ) . despite recommendations made by governments in many western countries including finland, sweden, uk, us and some regions in spain to deliver ppv to the elders and patients with chronic diseases, the vaccination rates vary substantially across countries. the uptake rates ranged from % in finland to % in the us (ruutu et al., ; united states department of health and human services, ) . several strategies involving health care professionals in improving the uptake rate of ppv have been proved effective in randomized trials. a computerized system reminding health professionals about the eligibility of patients for ppv increased the uptake rate from . % to . %, while an education program for patients through videotape-brochure was more effective than video-only and the control group (dexter et al., ; thomas et al., ) . a program with educational outreaching visits about the importance of vaccination to practicing physicians and a nurse-delivered education intervention to patients on discharge increased the vaccination rates (siriwardena et al., ; thomas et al., ) . however, to the best of our knowledge, no study on testing the use of a nurse-delivered brief telephone and face-to-face health education intervention to promote ppv uptake in asian countries has been reported. ppv has been recommended for elders by the hong kong sar government since october (hutchison et al., ) . prior to , vaccination for pneumococcal infection was not common and the estimated use of ppv was less than % for those aged over years (ho et al., ) . the uptake rate of influenza vaccination was also very low even after the outbreak of severe acute respiratory syndrome and substantial promotion from the government, as reflected by a study in hong kong which estimated that about % of patients visiting a public clinic did not have influenza vaccination within the past years of the clinic visit (mok et al., ) . consequently, additional efforts, other than mass media promotion, are needed to improve the uptake rate of vaccination. as ppv is relatively new to people in hong kong, it is important to implement and evaluate appropriate health education interventions to promote ppv and improve the vaccination rate, especially in vulnerable older patients with chronic diseases. nurses are the largest group of health care professionals who have the greatest frequency and duration of contact with patients, and thus have a strong potential to influence patients' behaviors. results: the vaccination rate was higher in the intervention group compared to the control group ( % vs %; relative risk = . , % ci = . - . ), but the two groups did not differ significantly in their awareness of the vaccination at -month follow up ( % vs %, relative risk = . , % ci = . - . ). discussion: a nurse-delivered brief health education intervention was effective in increasing uptake of pneumococcal vaccination among older patients with chronic diseases. ß elsevier ltd. all rights reserved. this large cluster randomized controlled trial, therefore, was conducted to test the effectiveness of a nursedelivered multiple component health education intervention on the uptake rate of ppv and awareness of ppv at month follow up among older patients with chronic diseases in hong kong. a single-blinded cluster randomized controlled trial with stratification by clinic was conducted from december to march for weeks (excluding the weeks of christmas and chinese new year) in the five hong kong hospital authority west cluster outpatient clinics. each week of the week study period was randomized to either intervention or control using random numbers generated by http://www.random.org. for each location, five weeks were allocated to intervention and five to the control. thus, there were clusters (i.e. study weeks) in the intervention and clusters in the control, making a total of clusters. two of the participating clinics are specialist outpatient clinics (sopcs) providing acute patient care and specialist services in cardiothoracic and pulmonary diseases, respectively. the remaining three clinics are general outpatient clinics (gopcs) which provide comprehensive primary medical care, serving an estimated population of . million in the central, western and southern districts of hong kong island, hong kong. subjects were eligible for inclusion if they were aged years or above, had chronic diseases (hypertension, cardiac diseases, diabetes, respiratory diseases, kidney diseases, liver diseases, and cancers), had no prior ppv and had scheduled medical appointments at the study sites during the study period. older patients who were cognitively impaired, not able to communicate effectively, had any febrile respiratory illnesses or other active infections were excluded. this study was approved by university of hong kong and the hong kong west cluster of hospital authority institutional review board on november , . lists of all patients with medical appointments from : am to : pm of the five study sites each of the study weeks were obtained from the respective clinics. one week before the medical appointments, two groups of trained research nurses (rns) of the project called the eligible subjects in the intervention and control groups separately to confirm whether their self-reported medical diagnosis matched the inclusion criteria, and if yes, they were invited to participate in the study while those could not be reached before their scheduled appointments were considered as missing the opportunity for enrollment into the study. after obtaining oral consent, the project rns responsible for the intervention group administered the baseline questionnaire and delivered the telephone health education intervention. the project rns responsible for the control group administered the baseline questionnaire only. the baseline questionnaire collected information on subjects' awareness of ppv, perceived stress, self-efficacy to manage disease in general, history of diseases and vaccinations, lifestyles and demographics. during the selected -week medical appointment sessions of the participating clinics, all patients, regardless of whether they had consented to participate in the study, received either the face-to-face health education intervention or standard care including promotional leaflets, poster displays, and health education video show, according to the cluster randomization. the -min face-to-face health education was delivered by the project rns or a group of two medical/nursing students (during their clinical practicum) supervised by one of the project rns in case there were students attending clinical practicum at the study clinics. however, only those who had consented and completed the baseline questionnaires before the medical appointments were included in the current study. ppv, if accepted, was administered by the nurses of the participating clinics to the patients according to the respective clinical procedures. all subjects were contacted via telephone at -week and -month follow-up after their medical consultations. trained research assistants who were blinded to subject group assignments conducted the telephone interviews using a structured follow-up questionnaire. the follow-up questionnaire collected information on subjects' selfreported ppv status, awareness and beliefs of ppv, barriers of not up taking ppv, perceived stress and self-efficacy to manage disease in general. a subject was considered as lost-to-follow-up after non-response to eight telephone calls made at different times of the day/night. the health education intervention comprised of parts, a -min brief health education telephone intervention before and a -min face-to-face health education intervention during subjects' medical appointments. the telephone briefing and face-to-face interventions, designed using the framework of pragmatism (baert, ) , included learning the facts of the health problem (pneumonia) and intervention (vaccination), and then the older patients were guided to interpret the given information from their own perspectives (to consider the pros and cons of receiving or rejecting the vaccination) so as to make decisions on whether to take the vaccination. the -min brief health education telephone intervention focused on the advantages and side effects of ppv, and highlighted the vaccine was free-of-charge at the selected clinics at the selected time. the face-to-face health education covered knowledge of ppv, including its nature and benefits, possible side-effects and care and support after receiving ppv. the control group received a reminder on their upcoming medical appointment after completing the baseline questionnaire. all study sites provided standard care including promotional leaflets, poster displays, and health education video show throughout the study period. fig. records the details of the health education intervention used in the current study. all the rns and medical and nursing students who were responsible to deliver the intervention had attended a oneday workshop delivered by the research team leaders on knowledge of ppv including its benefits and side effects, details of both parts of the health education interventions, study procedures and questionnaires, as well as communication skills with older patients. the primary outcome was the hospital authority clinical management system (cms)-recorded uptake rate of ppv by may . the secondary outcome was awareness of ppv at -month follow-up. in addition, reasons for not taking the ppv were examined at -week follow-up. the estimated % uptake rate of ppv reported previously in hong kong was not used for sample size calculation due to the changing situation in ppv provision in the community where ppv used to be only available in private clinics on a fee-for-service basis, and the hksar government now provides free ppv in selected public hospitals. thus, the required sample size calculated in the current study was on the basis of an increase in the vaccination rate from % to % (thomas et al., ) , a ratio of control to intervention participants of : , % power, and a significance level of %. we did not have prior information regarding the intra-class correlation coefficient (icc) on ppv in outpatient clinics in hong kong. previous studies reported icc was typically around . for primary care trials and usually less than . for community-based randomized trials (campbell et al., ) . as the current study included chronic patients receiving secondary care treatment in the clinics, we took the icc = . in calculating the sample size. this gave a target sample size of a total subjects, with subjects in each group. we enrolled subjects in each study week (one cluster) since there were study weeks ( weeks in clinics) available in the trial. proportions and means were used to summarize subject characteristics. generalized estimating equations (gee) at the individual level to allow adjustment for clustering by study week using an exchangeable correlation structure were performed to compare the primary outcome and the secondary outcomes between the intervention and control groups. in gee, models were fitted with adjustment for study week, clinic, three baseline variables of patient's educational level (primary level or below vs above primary level), whether had any type of vaccination in the past months, and whether was aware of ppv. a sensitivity analysis using gee was conducted by treating patients in the control group who also received the -min face-to-face health education at the clinic in the intervention group. relative risks (rrs) and their % confidence intervals (cis) were reported whenever applicable. fisher exact tests were used to compare the reasons for not receiving ppv at -week follow up. all analyses (except the sensitivity analysis) were performed using spssv . in and by intentionto-treat principle which is a strategy that compares study groups in terms of the treatment to which they were randomly allocated, rather than the treatment they actually received. in other words, analyses were performed according to the assigned treatment group, regardless of participant compliance, withdrawal or protocol deviation. also, for the secondary outcome of awareness of ppv at month, the patients who were lost to follow-up were treated as not aware of ppv. a total of , patients were screened for study eligibility in the participating clinics. of the eligible subjects, a total of ( %) agreed to participate with in the intervention group and in the control group. in the intervention group, ( %) of the subjects had received both the brief telephone intervention and the on-site face-to-face intervention (full compliance), while ( %) received the brief telephone intervention about ppv only (partial compliance). however, an on-site nurse reported that subjects in the control group also had also received the intervention but they remained in the control group by the intention-to-treat principle. a total of subjects ( %) in the intervention group and ( %) in the control group were successfully followed up at -week (follow up rate of %); and ( %) in the intervention group and ( %) in the control group at -month follow up (follow up rate of %) (fig. ) . the -month follow up was completed in june . the baseline variables between the intervention and control groups were similar (table ) . by may , , a total of ( %) subjects received the ppv injection during the study period as recorded in the cms, with ( %) subjects in the intervention group and ( %) in the control group. the icc of the cmsrecorded ppv uptake in the study by randomizing the study time in the participating clinics was . . when adjusted for clustering effects using gee, the adjusted relative risk (arr) for cms-recorded ppv uptake associated with the intervention was . ( % ci = . - . ). the intervention effect remained significant (arr = . , % ci = . - . ) after treating the patients in the control telephone briefing one week before the scheduled medical consultation . pneumococcal vaccine is now available free-of-charge at the selected sopcs/gopcs . you are encouraged to take this vaccination in the upcoming medical consultation at these sopcs/gopcs . the benefits of taking this vacc ination and possible side effects . we will meet you at the scheduled consultation session for further discussion . what is pneumococcal vaccine? . how does pneumococcal vaccine help to prevent pneumonia? . what are the possible side-effects? . how often should the vaccination take place? . what should be done in the post-vaccination period? . pneumococcal vaccine is now available free-of-charge at the sopcs/gopcs and you are encouraged to take this vaccination group who received the face-to-face health education as intervention subjects in the sensitivity analysis. the two groups, however, were similar in awareness of ppv at -month follow up (n = , % vs n = , %) and its corresponding icc was . . from the gee results, the adjusted relative risk for the awareness of ppv at month follow up was . ( % ci = . - . ), indicating no intervention effect. the intervention effect on the awareness of ppv remained insignificant (arr = . , % ci = . - . ) in the sensitivity analysis. at -month follow up, ( %) subjects of the intervention group and ( %) of the control group reported that the nurses had advised them to receive ppv, while only ( %) subjects of the intervention group and ( %) of the control group reported they received advice from the doctors. of the subjects completed -week follow up survey, ( %) subjects in intervention group and ( %) in control group did not receive the vaccination. exploratory analysis of these subjects revealed fewer subjects in the intervention group reported no need for the vaccination, had received all necessary vaccinations, and lack of knowledge about the availability and accessibility of the vaccination, while more subjects in the intervention group reported they did not want to receive ppv, as compared to the control group (table ) and these differences were statistically significant. it is worth noting that ( . %) subjects of the intervention group and ( . %) of the control group reported that they were suggested not to receive ppv by their physicians. a multiple-component brief health education intervention including a -min telephone briefing and a -min faceto-face education intervention was effective in motivating ( %) of the older patients to receive ppv vs ( %) in the control group, a % increase. although not directly comparable, the uptake rate in the intervention group was similar to a previous study using a nurse-delivered intervention with face-to-face patient contact. winston et al. ( ) reported a much lower uptake rate using a similar 'telephone outreach' intervention (< %) among a community older adult group (winston et al., ) ; and other studies reported a comparably higher uptake rate ( %) with a more intensive approach such as promotional intervention, educational brochures, and a reply card (krieger et al., ) . these results indicated that there are multiple strategies to improve vaccination uptake, and it seems that uptake rates may increase with intensity of the intervention. furthermore, both intervention and control groups showed a marked increase in the overall awareness of ppv (n = , %) at -month follow up comparing at baseline (n = , %), although there was no between group difference. the overall standard promotion of ppv at the clinics, and the telephone calls prior to the scheduled appointments for completing the baseline questionnaires might have exerted some effects on raising the awareness of ppv in both groups. providing health information such as promotional leaflet, poster, and educational video can raise the awareness of patients about the health problems, but adding a multiple component health education intervention, with direct communication with the older patients offering an opportunity for support can further motivate older patients to receive ppv. subjects in this study were older patients with chronic diseases and low education levels, and table baseline characteristics of subjects in the intervention and control groups, n (%) unless otherwise stated. intervention group (n = ) ppv, pneumococcal polysaccharide vaccine. a subjects in the intervention group and subjects in the control group did not complete the scale and were excluded from the analysis. b subjects in the intervention group and subjects in the control group did not complete the scale and were excluded from the analysis. hence these patients might need a more direct approach in communicating health messages such as face-to-face counseling, so that opportunities were given to ask questions, if any. about one-third of the patients who did not receive the vaccination reported that there was no need to receive the vaccine, suggesting more intensive intervention is needed to understand the reasons behind such thoughts and to motivate this group to consider the vaccination. although previous studies showed that advice from physicians on ppv was one of the crucial factors in promoting the uptake of the vaccination (united states department of health and human services, ) , family doctors at the clinics in hong kong have a very heavy workload that they can only spend a few minutes with every patient (hedley, ) . hence nurses can fill this important gap, and as indicated in this study, about two-third of the patients reported they had received advices from nurses about receiving ppv. it is worth noting that % (n = ) of the intervention group who did not receive ppv reported it was because of the expected side effects of ppv as compared to % (n = ) in the control group. this result suggested that the older patients might have negative perception on the health information provided by the nurses and developed some anxiety toward the vaccination leading to an adverse effect on the ppv uptake rates in the intervention group. further programmes thus should allow more time to discuss the side effects and adopt an appropriate balance of highlighting the benefits and possible side effects of ppv injection. finally, the study has provided estimate of icc on older patients with chronic diseases with regular visits to clinics for secondary care prevention which is very important in large vaccination studies as such an estimate of icc can enable accurate sample size estimation in further studies in a similar context. nevertheless, there were a few limitations in this study. first, the subjects were limited to older patients with chronic diseases and hence the results may not be entirely comparable to other studies which targeted all elders aged over years. furthermore, although all the five selected clinics were from the same region in hong kong, they had variations in their services provided and population served. for example, the three gopcs provided primary medical care services and their patients had less acute chronic illnesses such as hypertension, while the two sopcs provided follow up consultations, and their patients might have more acute illnesses and usually require more frequent follow ups. further studies with a wider coverage of all elders from different regions in hong kong would be desirable. second, only . % (n = ) of the patients in the intervention group had received both telephone briefing and on-site faceto-face intervention in the real clinical situation, hence the intervention effect could have been weakened. this situation was due to the busy day-to-day clinic routine, thus preventing the nurses from approaching all the randomized patients. in addition, some patients in both groups did not turn up at their scheduled appointments and hence did not receive the onsite intervention, leading to a . % (n = ) of the intervention group only received telephone briefing. although the sensitive analysis showed the intervention effect remained significant by treating the patients in the control group who had received the faceto-face health education at the clinics, future studies would require integrating health education into clinic procedures to improve efficiency. third, we had underestimated the icc in sample size calculation that the icc in this study was similar to clinical studies, not in between clinical and community studies (campbell et al., ) as expected. the underestimation of icc inevitably lowered the statistical power of the study. a retrospective calculation of the power of the study using an estimated icc of . indicating the study only has a power of . to detect a difference on % in the ppv uptake rates between the two groups at a % significance level. fourth, the physical space of some clinics was very small and crowded with patients with no designated space for delivering health education, hence limiting the quality of delivering the intervention. fifth, we had included medical and nursing students to deliver the second component of the intervention which might have induced variability in the quality of the intervention, although prior training was provided. because they had less experience in health promotion, the intervention effect might have been weakened. finally, only one-third of the eligible patients consented to the study which might also limited the generalizability of the current findings. the situation, however, was expected as ppv was very new to people in hong kong and a certain degree of reluctance to try a new type of vaccination is expected. furthermore, the study included multiple components and follow-up telephone calls and older patients might not want to be engaged into these activities. as a result, those participated in the study could be more cooperative and willing to take risks (from the patient's perspective) and hence willingness to receive ppv might be greater in both groups. a nurse-delivered brief multi-component health education intervention was effective in promoting and increasing uptake of ppv among older patients with chronic diseases. the traditional mode of uni-directional health education using pamphlets and videos can increase the awareness of health actions, but may not be able to change behaviors. physicians' advice has shown to be effective in increasing the uptake of ppv, but as nurses have more frequent contact with patients, they can fill this important gap and provide more direct communication with patients in motivating them to take appropriate health actions such as receiving ppv. pragmatism as a philosophy of the social sciences developments in cluster randomized trials and statistics in medicine prevention of pneumococcal disease: recommendations of the advisory committee on immunization practices (acip) a computerized reminder system to increase the use of preventive care for hospitalized patients prior pneumococcal vaccination is associated with reduced death, complications, and length of stay among hospitalized adults with community-acquired pneumonia problems in the delivery of primary health care in the public and private sections fluoroquinolone and other antimicrobial resistance in invasive pneumococci clinical effectiveness of pneumococcal vaccine. meta-analysis effectiveness of pneumococcal polysaccharide vaccine in older adults increasing influenza and pneumococcal immunization rates: a randomized controlled study of a senior center-based intervention pneumonia in older persons vaccines for preventing pneumococcal infection in adults prevalence of influenza vaccination and correlates of intention to be vaccinated among hong kong chinese epidemiology of invasive streptococcus pneumoniae infections in the united states, - : opportunities for prevention in the conjugate vaccine era communicable diseases cluster randomised controlled trial of an educational outreach visit to improve influenza and pneumococcal immunisation rates in primary care effects of a large-scale introduction of the pneumococcal polysaccharide vaccine among elderly persons in improving rates of pneumococcal vaccination on discharge from a tertiary center medical teaching unit: a prospective intervention patient education strategies to improve pneumococcal vaccination rates: randomized trial united states department of health and human services increasing pneumococcal vaccination in managed care through telephone outreach pneumococcal conjugate vaccines we would like to express gratitude to the five hong kong hospital authority west cluster outpatient clinics under hospital authority for their assistance during the study period.conflict of interest: none declared. funding: this study was supported by a donation from the li ka shing foundation, the university of hong kong and the hospital authority. key: cord- - hovffso authors: cherry, james d; krogstad, paul title: sars: the first pandemic of the (st) century date: journal: pediatr res doi: . / .pdr. . .fc sha: doc_id: cord_uid: hovffso nan sars (severe acute respiratory syndrome) was a new disease in the fall of , which first occurred in guangdong province, china and spread to countries with cases and fatalities ( ) ( ) ( ) . after an unprecedented global public health effort, the epidemic was controlled within mo of its original occurrence ( ). the scientific effort demonstrated unusual international cooperation and was facilitated by electronic communication. media coverage was incredibly accurate and provided worldwide pictures to augment scientific data. as of march , , there were citations related to sars in the medical literature. of interest, however, is that of these citations only . % are related to pediatric experiences. the purpose of this mini-review is to examine the unique pediatric aspects of sars, to review the epidemiology of the sars-cov in regard to future epidemics, and to use the sars experience as a model for future pandemics. the first train of transmission of sars occurred in fosham city, guangdong province, china ( , ) . during the period from november , , until february , , there were cases reported in guangdong province. sars was spread to hong kong on february , , by a patient from guangdong province who, before his hospitalization, stayed in the metropole hotel in hong kong for d. ten secondary cases occurred in hotel guests, and these infected persons led directly to tertiary cases in two hong kong hospitals and outbreaks in singapore, toronto, and hanoi ( ) . in march , a novel coronavirus (sars-cov) ( fig. ) was isolated from patients with sars and subsequently sequenced ( - ) . this virus was rapidly identified and characterized by a combination of classical virological methods and cutting-edge molecular biology. electron microscopic examination of swabs and sputum specimens from affected patients revealed the presence of viral particles. fortuitously, this newly identified agent replicated in vero cells, in contrast to other human coronaviruses. cytopathic effect was seen by - d after inoculation. in a technological blitzkrieg, the genome was completely and rapidly sequenced by several laboratories. a low-stringency, random primer reverse transcription pcr method was used by drosten et al. ( ) to amplify short fragments of dna using rna recovered from culture supernatants as the template. this method, previously used to identify the human metapneumovirus, was successful again: of fragments identified showed homology to known coronavirus sequences. in a similar approach marra et al. ( ) began by the construction of random primed and oligo-dt primed cdna library, beginning with viral rna recovered from a highly purified virus preparation. these and other molecular tricks of the trade were used to rapidly establish complete sequences of the sars-cov. this was no small feat. coronaviruses have the largest genomes ‫ , ف(‬ bases of positive-sense rna) found in any rna virus. these sequence data not only permitted the rapid development of highly specific diagnostic tests, but also helped in the epidemiologic tracking of the pandemic. moreover, cataloging the genome from human cases assisted in the search for the origin of this disease, when viruses related to the sars-cov were identified in animals [himalayan palm civets (paguma larvata) and raccoon dogs (nyctereutes procyonoides)] in a live animal market in shenzhen, china ( ) . viral genomes from nasal swabs from palm civets were . % homologous to the human sars cov, and represented a distinct phylogenetic group from the human isolates. moreover, early in the epidemic, open reading frame sequences from human isolates were identical to those from palm civets, suggesting animal to human transmission. as the pandemic progressed, most human isolates contained a sars-cov sequence with a deletion of nucleotides in this open reading frame. signature sequences were also identified in the amino acid sequences of the spike protein, which is involved in the attachment of viral particles. it is unclear whether these changes represent adaptive mutation to replication in humans. however, coronaviruses, like other rna viruses, mutate rapidly as a consequence of the error-prone nature of rna polymerases and their characteristically short replicative life cycles. thus, minor (perhaps inconsequential) mutations can emerge rapidly and persist as a founder effect. despite the known high rate of recombination seen with other coronaviruses ( ), there has been no evidence to date that this pandemic reflected the recombination of human and nonhuman coronaviruses, although this predilection could conceivably enhance the diversity of the sars-cov and result in a larger catastrophic pandemic. also of interest, in the investigation in the live animal market, was that of ( %) wild animal traders and of ( %) of those who slaughter the animals had antibody to the animal coronaviruses ( ) . in contrast, only of ( %) vegetable traders in the same market were seropositive, supporting the hypothesis that the sars-cov originated in these animals. the epidemiology of sars is both extremely interesting and frightening ( , , ) . as noted above, sars spread to hong kong on february , . the ten secondary cases associated with the metropole hotel lead to worldwide dissem-ination, which eventually involved countries ( ). how the secondary cases acquired the disease at the metropole hotel is not known. eight of the cases resided on the th floor, which was the same floor as the primary case. since the index patient vomited in the hall of the th floor and this was subsequently cleaned by vacuuming, it is possible that an aerosol was created. of particular interest was the point source outbreak, which involved the amoy gardens housing complex, kowloon bay, hong kong ( , , ) . the primary case in this outbreak was a -y-old man who lived in shenzhen. he had chronic renal disease and he frequently visited his brother in amoy gardens when he made visits to the prince of wales hospital, where his renal disease was being treated. on march and , , he visited his brother who lived in a flat in block e of the housing complex, which had high-rise units (blocks). the patient had diarrhea at the time of his visits and used the toilet in his brother's unit. during the following month, sars cases occurred in amoy gardens, with % occurring in block e residents. the peak of the outbreak occurred on march , , and the block e cases appeared earlier and showed a point-source-type distribution. subsequent study suggested that the secondary cases in block e were due to aerosolization of contaminated sewage through floor vents when toilets were flushed and exhaust fans in bathrooms were switched on. the transmissibility of the virus and human disease is a paradox. on the one hand, in the initial phases of the spread of sars in hong kong, singapore, and toronto, a disproportionate number of health care workers became ill and apparent "superspreader" cases were noted ( - , , , - ) . in contrast, the secondary illness rate in households was only % in a hong kong study and % in a study in singapore ( , ) . these household-contact rates are significantly less than occur with other respiratory infections such as pertussis and measles. with the exception of the amoy gardens outbreak and the secondary cases in the metropole hotel, most other instances of superspreading involved contact by hospital personnel who gave care and had contact with the primary cases without carrying out infection control precautions. sars spread rapidly around the world during march by infected persons who traveled by airplane. surprising, there were relatively few secondary cases acquired by co-airline passengers ( , ) . between february and may , , there were known airline flights with symptomatic probable cases on board ( ). a total of only secondary cases have been linked to probable cases of sars who traveled while symptomatic. however, on one flight from hong kong to beijing with one symptomatic passenger, of the ( %) contacts became ill. the incubation period of sars is - d, with a median of - d ( ). the attack rate in children is reported to be less than that of adults, but when consideration is given to the large number of nosocomial cases in original data sets, it appears that children have similar rates as adults. clinical disease in children is clearly less severe than disease in adults ( , , , , ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) . adolescents have illness similar to adults, but the case fatality rate in adolescents is significantly less. although there is evidence that unrecognized infections occur, there is only one reported instance of a possible asymptomatic infection with the sars-cov ( ) . details of clinical illness in children have been presented from studies in hong kong, singapore, toronto, and eastern taiwan. the largest single experience occurred at the princess margaret hospital in hong kong ( ) . the experience there was unique in that ( . %) of the hospitalized children were from the amoy gardens point-source outbreak. in a review of pediatric patients seen in toronto, singapore, and hong kong, the following clinical findings were noted: fever, %; cough, %; rhinorrhea, %; myalgia, %; chills, %; and headache, % ( ) . in patients Ͻ y of age, the most common findings when initially seen were fever and cough, whereas older children (Ն y) also had headache, myalgia, sore throat, chills, and/or rigor. in this study, all cases categorized as probable sars had abnormal chest radiographs or computerized tomography (ct). the most prominent radiographic findings were patchy infiltrates, opacities, and/or areas of consolidation. multifocal lesions were seen in % of the radiographs. hilar adenopathy, extensive pleural effusions, lung abscess, pneumatocele, or pneumothorax were not observed. on ct scan, unifocal or multifocal regions of consolidation and/or ground-glass opacities were observed throughout the lung fields. the most striking laboratory finding is absolute lymphopenia. this occurs in nearly all pediatric patients. in one study, % of children had lymphopenia on presentation, and this frequency rose to % ( ) . the mean value was . Ϯ . ϫ Ϫ /l. other frequently abnormal laboratory findings include thrombocytopenia and elevated lactate dehydrogenase and creatinine phosphokinase. the vast majority of children who were hospitalized with sars were treated with i.v. or orally administered ribavirin. in hong kong, most children were also treated with steroids, whereas in toronto none of the children received steroid treatment ( , , ) . only a small number of children required oxygen supplementation and intensive care and, to our knowledge, no fatalities in children have occurred. the initial diagnosis of sars was based upon clinical and epidemiologic data. the world health organization sars case definition is presented in the . high fever (Ͼ °c) and . cough or breathing difficulty, and . one or more of the following exposures during the d before onset of symptoms: close contact ‡ with a person who is a suspected or probable sars case-patient, history of travel to an area with recent local transmission of sars, residing in an area with recent local transmission of sars. probable case-patient: a suspected case-patient with: . radiographic evidence of infiltrates consistent with pneumonia or respiratory distress syndrome (rds) on chest x-ray or . consistent respiratory illness that is positive for sars coronavirus by one or more assays, or . autopsy findings consistent with the pathology of rds without an identifiable cause. ( ) . laboratory confirmation of a sars-cov infection can be determined by the demonstration of serum antibody by elisa, isolation of the virus from a clinical specimen, or the detection of sars-cov rna by a reverse transcription pcr assay ( , , ) . at the present time, there are two key questions that relate to sars: will the disease reoccur? and, if it does, how should it be treated and can it be contained? this year, two laboratory confirmed cases of sars have been identified in guangong province, china, and no secondary cases have occurred ( ) . severe disease in humans who are infected with animal viruses are an ever-present danger. although perhaps hiv infection is an exception, the only animal viruses that have caused pandemic human disease and continued human to human spread over periods of years are influenza a viruses. other severe diseases acquired from animals such as rabies, lassa fever, and ebola hemorrhagic fever, all of which can be transmitted from person to person, have not resulted in sustained human disease. it would appear that the sars-cov should also be similarly grouped. the sars pandemic of - had two initial events that led to its worldwide dissemination. in retrospect, it seems likely that aerosolization of the virus at the metropole hotel, amoy gardens, and perhaps in some nosocomial situations made the introduction of this virus different from experiences with lassa and ebola viruses. however, concern has to be raised as to the possibility of a future genetic recombinant virus with the sars-cov and a human respiratory cov such as oc or e strains. because live animals and humans have close contact in southern china and infections with human cov are common, dual infection seems quite possible. however, this type of recombination among different groups of cov has, to our knowledge, never been documented. far more likely, however, is the occurrence of a recombinant between a strain of avian influenza (such as h n ) and a circulating human strain (such as h n ). from past experience it appears that an influenza pandemic will occur in the next few years. hopefully, lessons learned from the international response to sars will contribute to its control. the pathophysiologic events in sars are not clear. the illness in adults is biphasic and occasionally triphasic ( , , , - , , ) . the biphasis illness is characterized by an initial febrile period, which is otherwise relatively symptom free, and then a period of respiratory symptoms, chills/rigor, and vomiting and diarrhea. maximum virus shedding occurs during the second phase. about % of adults will have a third phase characterized by acute respiratory distress syndrome. children in general have a single-phase disease and illness in adolescents is biphasic but generally less severe that that seen in older adults ( , , - ) . initial therapy, which was developed on medical services, used both antiviral (ribavirin) and anti-inflammatory (steroids) treatment. the rationale for steroids was based on the perception that severe lung damage was occurring as a result of a "cytokine storm" ( ) . this thought was enhanced by the fact that illness in sars was similar to illnesses in adults due to infection with avian influenza (h n ). laboratory studies with h n virus in tissue culture noted the induction of proinflammatory cytokines ( ) . the most notable laboratory finding in sars is the profound lymphopenia. cui et al. ( ) noted that cd ϩ t cells were reduced in all patients, cd ϩ cells in %, b-lymphocytes in %, and natural killer cells in % of patients. in patients who recover from sars there is a rapid restoration of lymphocytes in peripheral blood ( ) . sars-cov experimental infections in macaques suggest that pulmonary pathology is due to a direct viral effect on type pneumocytes ( ) . at the present, when therapy of pediatric sars patients is considered, it seems clear that there is no indication for routine treatment with steroids inasmuch as children in toronto who did not receive steroids did equally well as those treated in hong kong with steroids. in regard to antiviral therapy, it is disappointing that no laboratory data have become available regarding the evaluation of ribavirin treatment ( ) . at the present time, the use of ribavirin either i.v. or orally is the standard of care. laboratory studies have suggested that pegylated interferon-␣ and interferon-␤ might be useful therapeutic agents ( , ) . an uncontrolled study in adults in toronto suggested that patients treated with interferon alfacon- plus steroids had more rapid recovery than patients treated with steroids alone ( ) . although it seems unlikely to us that pandemic infection with the sars-cov will ever occur, there has been considerable effort to develop a vaccine ( ) . to us, this seems ill advised for two reasons. first, if a reoccurrence of pandemic disease were to occur, it is likely, since its origin will be from an animal, that the new virus will be different from the present human sars-cov. secondly, vaccines against known animal cov have had varied results. of particular concern in this regard is the possibility of enhanced sars rather than protection. this has happened before in humans with other rna viruses (measles and respiratory syncytial virus) and it has happened in the animal setting with a feline cov vaccine (denison mr, personal communication). at the present time, the most important factor in preventing a future epidemic or pandemic of sars, as well as epidemics or pandemics with other new viruses, is sound public health policy and the use of standard infection control procedures. sars gained a foothold because of an unusual event (probable aerosol dissemination), and the failure to recognize the problem and to initially use respiratory isolation procedures, and to use quarantine measures. in the united states in we were lucky because very few of the probable cases were actually infected with the sars-cov. in the spring of , one of us surveyed a number of hospitals, including our own, and found that if a patient with sars were to visit a clinic or emergency room, large numbers of persons would have been exposed before the problem was recognized. a further problem is that all hospitals built during the last y and those being built today do not have the capacity to handle large numbers of patients who require respiratory isolation. world health organization. summary of probable sars cases by onset of illness from severe acute respiratory syndrome (sars) consensus document on the epidemiology of severe acute respiratory syndrome (sars) update: outbreak of severe acute respiratory syndrome-worldwide the severe acute respiratory syndrome identification of a novel coronavirus in patients with severe acute respiratory syndrome characterization of a novel coronavirus associated with severe acute respiratory syndrome sars working group a novel coronavirus associated with severe acute respiratory syndrome the sars coronavirus: a postgenomic era isolation and characterization of viruses related to the sars coronavirus from animals in southern china recombination in large rna viruses: coronaviruses. semin virology outbreak of severe acute respiratory syndrome (sars) at amoy gardens, kowloon bay, hong kong, main findings of the investigation cluster of severe acute respiratory syndrome cases among protected health-care workers-toronto, canada severe acute respiratory syndrome (sars) in singapore: clinical features of index patient and initial contacts a major outbreak of severe acute respiratory syndrome in hong kong secondary household transmission of sars probable secondary infections in households of sars patients in hong kong transmission of severe acute respiratory syndrome on aircraft clinical features and short-term outcomes of patients with sars in the greater toronto area acute respiratory distress syndrome in critically ill patients with severe acute respiratory syndrome hku/uch study group clinical progression and viral load in a community outbreak of coronavirus-associated sars pneumonia: a prospective study severe acute respiratory syndrome in children infants born to mothers with severe acute respiratory syndrome inflammatory cytokine profile in children with severe acute respiratory syndrome severe acute respiratory syndrome in children: experience in a regional hospital in hong kong other members of the hospital for sick children sars investigation team children hospitalized with severe acute respiratory syndrome-related illness in toronto a young infant with severe acute respiratory syndrome adolescent twin sisters with severe acute respiratory syndrome (sars) severe acute respiratory syndrome (sars): chest radiographic features in children asymptomatic severe acute respiratory syndrome-associated coronavirus infection world health organization case definitions for surveillance of severe acute respiratory syndrome (sars) update: influenza activity-united states, - season detection of sars coronavirus in patients with suspected sars combining clinical and epidemiologic features for early recognition of sars sars-one year later severe acute respiratory syndrome-associated coronavirus in lung tissue induction of proinflammatory cytokines in human macrophages by influenza a (h n ) viruses: a mechanism for the unusual severity of human disease expression of lymphocytes and lymphocyte subsets in patients with severe acute respiratory syndrome significant changes of peripheral t lymphocyte subsets in patients with severe acute respiratory syndrome pegylated interferon-␣ protects type pneumocytes against sars coronavirus infection in macaques antiviral treatment of sars: can we draw any conclusions? treatment of sars with human interferons interferon alfacon- plus corticosteroids in severe acute respiratory syndrome: a preliminary study caution urged on sars vaccines key: cord- -tj iv v authors: hui, eddie chi man; liang, cong; ip, wai-cheung; ho, david kim hin title: examining structural changes in asian offices market date: - - journal: land use policy doi: . /j.landusepol. . . sha: doc_id: cord_uid: tj iv v it is complicated to measure the effects of various economic events on office markets within a non-parameter modeling framework. in response to this issue, a non-parametric statistical method-wavelet analysis is introduced in this study. based on this innovative technique, we not only could detect the abrupt change points with a comparatively small data sample, but also could evaluate the impact from the abrupt change points by reconstructing the wavelet coefficient/de-noising the raw data, which had never been considered in previous studies of office markets. our empirical results suggest that the wavelet reconstruction method, to some extent, makes it easier for the detection of the existence of structural change points. more interestingly, our findings also indicate that free market economies (i.e. hong kong and singapore) are mainly influenced by the effects of global events, whereas the actual (net) impact on socialist economies (i.e. beijing and shanghai), depends on both the openness of the economies, and the magnitude of counter domestic forces put in place. how do economic events affect real estate markets? it is one of the topics that has long been getting the attentions of researchers and policy makers alike. loosely speaking, economic events which have significant effects on real estate markets are usually classified into two categories: global events and domestic events. it is believed that real estate markets are subjected to global economic events in market economies (renaud, ) . meanwhile, in socialist economies, governments intervene in property markets in response to the impacts of similar events (tian and ma, ). in other words, the real estate markets in different economic systems are influenced by different factors. for instance, on july , the day after hong kong's handover to china, the asian financial crisis began. hong kong's real estate market had been badly hit, with property price index having fallen by more than %. even to this day, the real estate index has yet to return to its peak level prior to the handover. meanwhile, the chinese government responded to the financial crisis by stabilizing the renminbi (rmb). therefore, the non-convertibility protected rmb's value from speculative activities on it. besides, by maintaining the peg of rmb, china's standing within asia has improved. it has been reported that this policy measure effectively protected china's real estate markets during the crisis. a study of how latent structural changes in real estate markets (i.e. housing prices), with respect to similar events, differ between free market economies and socialist economies would fill the existing knowledge gap in the literature. it has been pointed out in a variety of studies that housing price is affected by factors such as interest rate, land supply, and inflation rate (tian and ma, ; tsatsaronis and zhu, ) . previous researches have usually concentrated on parameter models such as regression models on housing price and on the correlations between price and various factors. in order to generalize the regression analysis for practical reasons, some assumptions are needed to be set regarding the sample data. this method, however, not only overlooks the issue of multicollinearity of the sample data, but also dismisses the jumps. it is observable from the market that jumps may appear in time-series housing price index data. moreover, the study on the magnitude of the jumps, or the impact from events, is rarely seen in real estate literature. in this paper, we intend to investigate whether or not a change appears when an economic event takes place in an office property market. more specifically, we will apply the method, introduced by ip et al. ( ) and donoho and johnstone ( ) , of wavelet change point detection and wavelet coefficient reconstruction techniques to study the office indices of four renowned asian cities: beijing, shanghai, hong kong, and singapore. one feature that distinguishes this method from the others is that it is applicable to smaller data samples within a non-parameter framework. besides, we aim to employ the wavelet coefficient reconstruction method to explore office markets in cities under different economic systems and to find out how the latent structural changes differ among these markets. a study of which could provide a useful reference for future investigations of housing markets of other international cities. this paper is organized as follows. after a brief introduction, we discuss relevant literature on the approaches for detecting cusps, jumps and change points in 'literature review' section. 'model' section presents the wavelet analysis model for jump point detection and de-noise reconstruction. 'empirical studies' section reports the findings, and hence identifies and discusses some important events in the corresponding points. the last section concludes the paper. a great number of approaches have been utilized for testing structural change points (wu and chu, ; bernier, ; perron, ) . mathematically, fourier transforms and statistical methods are common methods to detect change points. rachev and sengupta ( ) studied the "stability" properties of laplace and a mixture of laplace and weibull in modeling price changes. lombard ( ) detected cusps by a fourier analysis. indeed, the fourier transform only converts the data into a signal process, whilst neglecting other information such as the location of the frequency. in other words, the method is unable to inform us the location effect within various time periods. to address this particular issue, muller ( ) introduced a non-parametric method to estimate the location of cusp(s) and its(their) size. this approach is closely related to the boundary kernels framework. nevertheless, it is still hard to find a criterion to detect a jump point. compared to the model provided by muller ( ) , eubank and speckman ( ) employed a semiparametric approach to detect the discontinuities in the derivatives of regression functions. they loosened the requirements of smooth higher derivatives for the function. however, similar to muller's method, eubank and speckman's approach also requires a large data sample. statistically, andrew and meen ( ) employed aggregate time-series data to find the relationship between house prices and transactions in the u.k., and discovered a change point during the s. lavielle and teyssière, used the method proposed by andrew and meen ( ) to analyze the returns from real estate and financial investments. lavielle and teyssiere also considered the bivariate series of returns on ftse and s&p index, and the results showed that some major changes upon economic events are detected. another study by strikholm ( ) focused on the us ex-post real interest rate series. he used a sequential method to determine the number of breaks in piecewise linear structural break models. hillebrand and schnabl ( ) concentrated on the effect of japanese foreign exchange interventions on the volatility of the yen/dollar exchange rate. a change point detector was used for the segmentation of the data. furthermore, bourassa et al. ( ) developed a model of the repeated sale of residential single-family properties and investigated the impact of housing characteristics on the rate of appreciation. their findings suggested that the average change in house prices is related to changes in national and local macroeconomic variables or marketwide bubbles. nonetheless, their method only applies under the hypothesis that housing price adjustments only depend on housing characteristics as well as change in the strength of the housing market. elíasson and pétursson, studied the structural change in the icelandic housing market, with the focus mainly on the regression analysis. more recently, hui et al. ( a,b) presented a new abrupt change point detection method -a wavelet analysis on hong kong's residential real estate market. they pointed out that the detected change points are closely related to events, which are not observable directly. however, hui et al. ( b) only used a conservative standard for the selection of the benchmark/threshold in identifying these change points. in addition, the study did not proffer an efficient way to measure the impact of each change point. as wavelet analysis has some desired properties, it is suitable to deal with the problems containing the information from real estate markets, which do not require any hypotheses with regard to the market (e.g. market equilibrium). donoho and johnstone ( ) brought about selective wavelet reconstruction technique, which generalized the traditional wavelet detection analysis using smaller samples. wang ( ) suggested a method to detect jumps and sharp cusps in a function, which was observed with noise by checking if the wavelet transformation of the data has significantly large values (in absolute terms) across fine scale levels. the limitation of his method is probably the assumption of uncorrelated white noise about the data series. ip et al. ( ) proposed a wavelet approach to detect jumps or cusps of a discontinuous function in the presence of a noise. they applied their method to the daily exchange rate of us dollar against deutsche mark from august to july , with convincing results in which all the points detected reflected strong economic and political impacts. compared with the three other methods, their method was the most reliable one. more recently, lai and huang ( ) applied wavelet transform in china's real estate stock market, but due to the lack of data support, the analysis rendered to be qualitative in nature. overall, wavelet analysis is a powerful and versatile tool in detecting and measuring abrupt change points by using relatively small sample data sets. in the following section, we intend to employ ip et al. ( ) and donoho and johnstone ( ) in our change point analysis. the following global events are believed to have had major impacts on the real estate office market. this is followed by a discussion of specific asian events. ( ) the asian financial crisis was a period of financial crisis that gripped much of asia beginning in july , and raised fears of a worldwide economic meltdown due to financial contagion. as the crisis spread, most of southeast asia saw slumping currencies, devalued stock markets and other asset prices, and a precipitous rise in private debt. hong kong was hurt by the slump, while the people's republic of china and singapore were less affected, although all suffered a loss of demand and confidence throughout the region. ( ) the subprime mortgage crisis is an ongoing real estate and financial crisis triggered by a dramatic rise in mortgage delinquencies and foreclosures in the united states, with major adverse consequences on banks and financial markets around the globe. the crisis, which had its roots in the closing years of the th century, became apparent in and exposed the pervasive weaknesses in financial industry regulations and the global financial system. approximately % of u.s. mortgages issued in recent years to subprime borrowers were adjustable-rate mortgages. when u.s. house prices began to decline in - , refinancing became more difficult and as adjustable-rate mortgages began to reset at higher rates, mortgage delinquencies soared. securities backed with subprime mortgages, widely held by financial firms, lost most of their value. the result was a large decline in the capital of many banks and u.s. government sponsored enterprises, tightening the credit granted around the world. it is expected that this serious effect from u.s. would "contaminate" asian real estate markets. ( ) as the news of lehman brothers' bankruptcy broke out in mid-september , the global financial market soon fell into an abyss of pessimism, giving rise to the sharp reduction in the scale of production. from the investors' point of view, the global financial crisis hit the real estate market the hardest, and the change point was found in asian real estate markets. asian cities' events singapore ( ) in , the unemployment rate of singapore rose to a -year high, and million square feet of office spaces were vacant due to the worst recession in the past four decades. home price, office price and rent dropped drastically. high unemployment rate indicates that more people have to delay their homeownership plans due to the lack of a stable source of income. housing demand is expected to decrease. in addition, high vacancy rate of office spaces would have indirect influence on housing market. companies were expected to contract their scales, meaning that the economic depression would likely continue. ( ) in february , prices of luxury residential properties rose by - % with strong demand from overseas companies. straits times index rose to its highest in years. the price increase in the luxury residential market would have spill-over effects on the non-luxury residential and office markets. even though overseas companies have no interest in non-luxury residential housing and office, local investors may turn to these houses since they may consider that these houses would have higher return than luxury houses. (ding, ) . ( ) in q , the state council launched a second round of supply-side regulations as well as regulations on foreign investment on the housing market. during that time, gosc issued a notification urging all municipality governments to improve the housing supply structure, in order to stabilize the appreciation of housing prices. therefore, a slow down on housing price adjustments would be expected in the long run, given the possibility that more housing units are to be supplied under the restriction on unit size (tian and ma, ). as our objective is to investigate change points in the real estate office markets, consider the following non-parametric model introduced by ip et al. ( ) : where x(t) is the data observed from the markets, usually with the noise term, and x(t) ∈ r (real set), s(t) is the true value signal, a deterministic function with finite discontinuous points and n(t) is a zero-mean stationary noise. the signal s(t) is assumed to possess p jump points, i.e., there exists t < t < · · · < t p , such that where s(t k − ) and s(t k + ) are the left-limiting and rightlimiting values of s(t) respectively and p is a positive integer. except these points, s(t) is differentiable on r with bounded derivatives. the problem associated with the detection of change points is ascribed to test following hypothesis: h : = = · · · = n h : = = · · · = j / = j+ = · · · = n with unknown index j, j stands for the expected value of the data at time j. however, as indicated in ( ), the model is nonparametric, which means that the model is distribution free so that it is not possible to test the mean value of collected data directly. therefore, we consider the discrete wavelet transform. define the wavelet function where « (t) is called the mother wavelet. then the wavelet transform of a function s(t) is w j,k r s(t) j,k (t)dt, k ∈ z, j = , , . . . . which will result in a sequence of wavelet coefficients. z is the integer set. consider wavelet « (t) of meyer function as defined by: thus far, a series of coefficients through wavelet transform is acquired from formula ( ). however, we still need to know the threshold (benchmark) value for the testing of the hypothesis as listed above. as such, we consider the minimax threshold rules, as introduced by donoho and johnstone ( ) , which retain only observed data that exceeds a noise level. let where w i is the wavelet coefficient transformed via formula ( ), and , is the threshold value. Á s and Á h stand for hard threshold and soft threshold respectively, and |a| stands for the abstract value of a. in the following section, we focus on the soft threshold Á s in the following section. define the minimax quantities: * n ≡ inf sup min( , ) n − + min( + ) ( ) * n ≡ the largest attaining * n above ( ) consider the analog quantities where the supremum over the interval [ ,∞) is replaced by that over the endpoints { ,∞}. thus, we denote n ≡ inf sup ∈ { ,∞} min( , ) n − + min( + ) it is quite clear that n = * n (donoho and johnstone, ) . then we wish to estimate the -loss to find out the minimax threshold * n , with the following equality equation: where  = ( ,  . . .  n ), ε is a constant. then the minimax threshold * n should be the one that satisfies for further detail of the above ( )-( ), see donoho and johnstone ( ) . as the orthogonality of the discrete wavelet transform has a fundamental statistical consequence: w is the orthogonal transformation matrix. hence, if {x j,k } are the wavelet coefficients of (x(t)) n− t= collected according to model ( ), then w j,k are the wavelet coefficient of (s(t)), then with the property of isometry of risk, our interest is to find an estimateŝ of s = (s(t)) in the other domain by: whereŵ andŝ obey the parseval relation ||ŵ − w|| = ||ŝ − s|| . ||a − b|| is the distance between a and b in the -order laplace space, or the space of functions whose square-term has a definite integral. as an advantage for using the wavelet detection and reconstruction, we intend to use ( ) as well as ( ) to detect the change point at the outset, and carry out our discussion by utilizing ( ) in the following section to de-noise the raw data, and then to further analyze the residuals/estimate of the change points error based on the findings. the reasons to study the four real estate office markets (beijing, shanghai, hong kong and singapore) are obvious. first, these four markets are prominent metropolitan cities in asia, in terms of business scale, gdp, and population size. recently, these four cities are termed as the top four cities for real estate investment by forbes. http://www.forbes.com/pictures/gg ejhmd/ -singapore/#gallerycontent second, beijing and shanghai are emergent markets in a developing country, so much so that they are being called the frontline cities in china (liu et al., ) , where the business and real estate markets are vibrant. as a result, real estate office markets of these two chinese cities may have sensitive market reaction towards various events. hong kong and singapore are the developed markets that respond to these events quickly. as such, a study of these markets provides a good understanding of real estate office markets between developed regions and developing regions. in addition, an investigation of the jump points hidden in the real estate office markets is to be carried out as well. the relationship between office price indices of four selected asian cities (beijing, shanghai, hong kong and singapore) from the st quarter of to the nd quarter of is also examined in this section. the reason to choose the office price index attributes to the fact that changes in office real estate markets are much more sensitive than those in stock markets. in fact, office real estate markets are often subjected to unemployment rate, foreign investment, and government policies (tse, ; hui and yu, ) . office price lags behind stock market by about three months (hui et al., ) . so the use of quarterly data is considered both reasonable and feasible for our data analysis. to facilitate our analysis, it is assumed that the detected change point, corresponding to the real estate market, is found at least three months after an event takes place. in addition, we attempt to analyze the wavelet coefficients for each city and then to illustrate that the change points are closely related to either local or global events. the historical data of these four asian cities are collected from jones lang lasalle. fig. shows the time series plot of the office price indices of the four cities. it is quite obvious that the trends of singapore's and hong kong's indices were quite similar. both began with a slightly downward trend, followed by a short period of fluctuations that took place before a marked upward trend. after that, both indices noticeably fell from their peaks around q . in contrast, the indices of shanghai and beijing seem to have maintained a relatively stable trend. in order to examine the linear relationship between these four office markets, we calculate the correlation coefficients, which are illustrated in table . it is apparent that the correlation coefficients between beijing and any one of hong kong, singapore and shanghai office markets are quite similar, which means, any of these three cities is nearly uncorrelated (the perfect correlated coefficients is ). on the contrary, shanghai is closely correlated to hong kong as well as to singapore. hong kong shows a perfectly correlated status with singapore, which coincides with our initial discussion above. it is shown that change points hidden in office real estate market are not easy to detect via observations. on utilizing the non-parametric change point method-wavelet analysis, the data for each office real estate market was transformed to wavelet coefficient. for coefficients that significantly pass through the note: the symbol " √ " indicates that at least one abrupt change point happen during the corresponding period. benchmark (minimax threshold), they are regarded as structural change points. these change points represent the statistical landmarks that are over the chosen threshold value. the current wavelet technique can detect multiple change points, if they exist. this technique is much superior to that of cannarella et al. ( ) since they allow to detect only two change points. the detected abrupt change points are roughly - months behind the occurrence of certain events (table ) , which coincide with the findings of hui et al. ( a) , and are in line with general belief. surprisingly, for each event, there is no consistent effect for the four office markets during the same period, which somewhat differs from the result in ip et al. ( ) . this outcome is mainly due to the fact that these four markets are within different economic systems. for instance, shanghai and beijing are planned economies, while hong kong and singapore are market economies. specifically speaking, before , change points are found in the beijing and shanghai office markets. during this period, chinese office real estate markets had experienced severe acute respiratory (sars) in , and later the "state council's eight points" and "the regularity notification with regard to further strengthen and stabilize the foreign direct investment in real estate". the latter two reflect the chinese government's determination to regulate the real estate market, especially the office market. hence, it is not surprising that these abrupt change points are primarily found between and . in contrast, without direct government intervention in their respective property markets, hong kong and singapore were comparatively more susceptible to economic events such as the two financial crises in and respectively. as a result, a series of change points have been detected during this period (fig. ) . as illustrated by the de-noise plot of the four office markets (fig. ) , however, an apparent and sharp downturn can be observed for beijing's office market in q , as compared to the original data plot. de-noise technique is used to estimate the true value signal s(t). the comparison in fig. is in fact the comparison between x(t) and the estimation of s(t). few differences between these two graphs emphasize that traditional methods cannot detect much more change points using de-noise data compared with either original data. it is showed that the wavelet analysis is preferable. this indicates that the non-parametric non-linear smoothing process alternatively strengthens our belief that the detected change points during that period are the structural change points. those structural changes result in long-term effects to office markets. as wavelet analysis has properties for detecting the abrupt change points in a non-parameter non-linear modeling framework, it is much more powerful and thus more useful to investigate the structural changes in office markets than traditional statistical methodologies such as linear regression models. also, as the wavelet analysis is applicable to smaller data samples, it allows for the exploration of newer office markets such as those in chinese cities. our study has compared the change points' effects ( fig. ) of various cities under different economic systems and the findings point out that some change points in the office markets of four asian cities have been detected and that they occurred - months after significant global and local events. the office sector is not significantly affected by the financial crisis in beijing and shanghai. yet, government interventions in the economy are not able to deal with non-financial, local crises such as the outbreak of epidemics. in contrast, free market economies (i.e. hong kong and singapore) appear to be more susceptible to global events/crises, but subsequently would trigger a self-adjusting mechanism to recover from a changing environment. house price appreciation, transactions and structural change in the british housing market: a macroeconomic perspective statistical detection of changes in geophysical series house price changes and idiosyncratic risk: the impact of property characteristics unit roots and structural change: an application to us house price indices policy and praxis of land acquisition in china ideal spatial adaptation by wavelet shrinkage the residential housing market in iceland: analysing the effects of mortgage market restructuring nonparametric estimation of functions with jump discontinuities a structural break in the effects of japanese foreign exchange intervention on yen/dollar exchange rate volatility detecting jump and cusp points of asian real estate markets jump point detection for real estate investment success office price index lagging in singapore and hong kong de-lagging hong kong's office price indices via state space model with kalman filter on comparison of jump point detection for an exchange rate series the application of wavelet transform in stock market detection of multiple change-points in multivariate time series the classification and value-added calculation of real estate industry detecting change points by fourier analysis change-points in nonparametric regression analysis dealing with structural breaks. working papers series wavelet methods for time series analysis laplace-weibull mixtures for modeling price changes the - global real estate cycle: are there lasting behavioral and regulatory lessons? determining the number of breaks in a piecewise linear regression model government intervention in city development of china: a tool of land supply what drives housing price dynamics: cross-country evidence impact of property prices on stock prices in hong kong jump and sharp cusp detection by wavelets kernel-type estimators of jump points and values of a regression function this paper is funded by the hong kong polytechnic university internal grant (project #: g-yk , -zzc , and -zzc ). key: cord- -tjnt ld authors: argyroudis, george s.; siokis, fotios m. title: spillover effects of great recession on hong-kong’s real estate market: an analysis based on causality plane and tsallis curves of complexity–entropy date: - - journal: physica a doi: . /j.physa. . . sha: doc_id: cord_uid: tjnt ld this paper investigates the impact of the sub-prime loan crisis on the real estate market of hong-kong. based on permutation entropy, complexity–entropy causality plane and tsallis complexity–entropy curve, we characterize the complexity of the housing indices-both in terms of size and region-and distinguish the level of informational efficiency. by calculating the quantifiers we report that most indices exhibit a behavior equivalent to a persistent stochastic dynamics with hurst exponents between . and . . the outbreak of the crisis had changed the dynamical structure of the indices decreasing the level of randomness and increasing considerably their regularity and predictability. only the index of the kowloon area seems not impacted by the crisis, exhibiting higher levels of informational efficiency. the results are robust based on the utilization of two different entropy definitions: the shannon and tsallis-q entropy. lastly, with the temporal evolution of the indices, we identify periods where the underlying dynamical structure of the market was impacted by certain events like the sars epidemic and the imposition of special stamp duty on housing. the - financial crisis in the u.s.a. caused an unprecedented international turmoil. the substantial growth both in mortgage credit and in housing prices initiated an increase in mortgage delinquencies, as interest rates increased sharply. the burst of the housing bubble and the meltdown of the associated prices triggered a chain of reaction to other financial markets, both domestically and internationally. asset prices across the globe fell, while financial volatility rose substantially. among the markets, where prices plummeted considerably, were the housing markets and particularly those that historically have exhibited higher volatility. the aim of this paper is to investigate the effects of the u.s. real estate collapse on other housing markets and particularly on hong-kong area. the rationale for testing the particular region is that the hong-kong housing market could be considered as an ideal laboratory, based on the robust demand for properties, the relatively low interest rates environment for a long period of time and the large and frequent increases in property prices. more precisely, house prices have tripled in hong-kong from to while construction surged sharply. the real estate sector, and particularly the housing market under stress has been much less studied compared to other economic assets, and also little is known as far as the information efficiency of real estate markets is concerned. moreover, an important discourse in the discussion of the real estate market is the relevance of the theory of efficient market hypothesis (emh). according to emh, efficient prices reflect all available information, and follow a rather ''random walk'' where it is impossible to make a profit systematically, or above average return (fama [ , ] ). put differently, the market is able to absorb the information of yesterday's price change, without influencing today's price change, making thus the stock market memory-free. the well-known example in malkiel [ ] of a chimpanzee throwing darts to select a portfolio that would do as well as the portfolio of an expert displays the notion about the emh. nevertheless, the intellectual dominance of the emh and the assumption that prices are random walks was put into question, a number of times especially during anxious times. according to empirical evidence, levels of inefficiency can be found even in the most competitive markets. shiller [ ] challenged emh and asked why an efficient stock market should be that volatile, when the actual price should have been the same as the optimal forecast? the dot-com crisis demonstrated that for a short period of time pricing irregularities and predictable patterns can take place. after all, as grossman and stiglitz [ ] noted, prices cannot reflect all available information, because if they did, there would not have been any incentives for the informed traders to spend their resources to receive compensation. the emh theory was unconfirmed in the findings of numerous articles. for example, barkoulas and baum [ ] with spectral analysis applied to stock returns of some companies included in the dow jones industrial index, found no fractal structure but some evidence of long memory. ito and sugiyama [ ] showed that the market efficiency in us stock market is not stable but rather fluctuates through time; it was more inefficient during the late s, and became efficient around . moreover di matteo et al. [ ] reported an inclination from pure brownian motion. eom et al. [ ] report a positive relationship between the predictability of the hit rate and the degree of efficiency, concluding that the prediction of future price changes is feasible by using the hurst exponent as a measurement. bariviera et al. [ ] studied the long varying behavior of sovereign and corporate bond markets of seven eu countries. using the detrended fluctuation analysis (dfa) and the sliding window technique, they report different memory dynamics in bond indices, after the great recession. against the theory of randomness by bachelier [ ] , zhang [ ] introduced a new approach named conditional entropy, which measures possible profit pockets that could be revealed from the inefficiency margin in market dynamics. zunino et al. [ ] in an attempt to discriminate the market dynamics report that developed stock markets have lower number of forbidden patterns and higher normalized permutation entropy than the emerging ones. in zunino et al. [ ] , the complexity-entropy causality plane is used to classify the stage of stock market development. the developed stock markets show higher entropy and lower permutation complexity, while the emergent stock markets behave in the opposite way, with signs of time correlation and inefficiency. also, zunino et al. [ ] presents a complexity-entropy causality plane for bond indices, a non-exhaustively studied sector. the findings confirm that permutation entropy is higher for the developed countries, and market size is correlated with permutation entropy, showing that developed and emerging bond markets differ. bariviera et al. [ ] investigated the impact of two economic situations on the informational efficiency of european sovereign bond markets. the establishment of the common currency produced diverse informational efficiency levels among the countries and was negatively affected by the financial crisis. in serinaldi et al. [ ] the position of chaotic deterministic systems are located in the upper left region of the plane, while the stochastic and noisy signals are closed to the limit point ( , ). bariviera et al. [ ] use the concepts of permutation entropy and permutation statistical complexity to reveal the temporal correlation of interest rates, and more specifically the libor rate. using sliding window to show the evolution of these quantifiers, a complex behavior is revealed, and temporal correlations in libor rates are shown. zunino et al. [ ] analyzed the efficiency of the european corporate bond sectorial indices before and during the financial crisis of . the sectors that are connected to the financial economy like financial banks, insurance, basic resources and financial services have presented lower informational efficiency. on the other hand, sectors related to the real economy like healthcare, food & beverage and utilities presented less change in the informational efficiency. in bariviera et al. [ ] , the efficiency of crude oil market is questioned. the authors concluded that during important economic events the efficiency of the oil has changed. lastly, several works applied the entropy concept to quantify the efficiency level in various financial markets, oh et al. [ ] , risso [ ] , alvarez-ramirez et al. [ ] , martina et al. [ ] , and ortiz-cruz et al. [ ] . in this paper we examine the evolution of the informational efficiency of the real estate market in hong kong on a size-based and on a region-based perspective during the - period. we want to understand the changes in the statistical characteristics of the real estate market during a period of anxious time. by identifying the statistical properties of the housing market indices under stress, we hope to improve our perception about the mechanism behind the dynamics of the real estate market and to develop predictive models for real estate price changes. we are studying the informational efficiency level, before and after the financial meltdown of , by using the permutation entropy concept. different hong kong price indices are used based on (a) region namely the hong kong mass, hong kong island, kowloon, new territories east, new territories west, and (b) size like the general housing price index for overall flat sizes, large housing price index and medium/small housing price index. flats with net floor area over sq. ft. are included in the large housing price index. the remainder of the paper is organized as follows. in the following section we describe the information-permutation theory, in terms of shannon and tsallis entropies. in section we describe the data used followed by the presentation and discussion of the empirical results obtained from the different indices of the housing markets. in section we summarize the findings of the paper and conclude. entropy is a general concept of information theory, and it is expressed in terms of a discrete set of probabilities. the estimation of the associated probabilistic distribution comprises as the first step for the calculation of the so-called entropy quantifier, for a given time series. various methods have been suggested for the estimation of the probability distribution. these methods are, the fourier analysis, introduced by powell and percival [ ] , the wavelet transformation by rosso and mairal [ ] , the symbolic analysis by daw et al. [ ] and the amplitude statistics (micco et al. [ ] ). in our case we utilize the permutation entropy, a procedure introduced by bandt and pompe [ ] (b&p) in order to construct a probability distribution from a time series. the b&p approach is based on the celebrated shannon entropic measure, and several applications drawn from scientific disciplines; from medical issues, like observing the results of anesthetic drugs (jordan et al. [ ] , li et al. [ ] , olofsen et al. [ ] , li et al. [ ] ), or epileptic seizures (cao et al. [ ] , li and richards [ ] , bruzzo et al. [ ] ) to various uses refer to astrophysical plasmas (weck et al. [ ] ), and financial markets as well. the complexity of arbitrary time series is calculated using an ordinal pattern, and then time causality is assessed from the comparison of the adjacent values. the main advantages of permutation entropy, as set forth by zunino et al. [ ] are its robustness, simplicity, its invariance considering nonlinear monotonous transformations, applicability to any type of time series, the fact that it does not require a large sample size like for instance in fractal analysis, and lastly that it provides a fast computational algorithm. for the permutation entropy the degree of structure in a process is not quantified by randomness measures, and therefore it is necessary to obtain measures of statistical complexity. those measures were firstly introduced by lopez-ruiz et al. [ ] , which manage to identify essential dynamics, and distinguish different degrees of periodicity and chaos. also, the embedding dimension d defines the number of symbols that formulae the ordinal pattern, and guides for the necessary length of time series in a way that the condition m ≫ d! is necessary for reliable statistics. given a time series {x t : t = , . . . , m}, an embedding dimension d > , and a time delay τ , we consider the ordinal patterns of order d which are generated by a segment s→(x s−(d− )τ , x s−(d− )τ , . . . , x s−τ , x s ). the ordinal pattern of the time series is the permutation π = (r , r , . . ., r d− ) of the index set ( , , . . . , d − ) corresponding to the ranking of the x in ascending order, namely x s−r d− τ ≤ x s−r d− τ ≤ · · · ≤ x s−r τ ≤ x s−r τ . in order to get a unique result we consider that if x s−r i τ = x s−r i− τ then r i < r i− . for all the d! possible permutations π i of order d, their associated relative frequencies can be computed by where # stands for frequency of occurrence of π. also p = {p(π i ), i = , . . ., d!}. the permutation entropy is defined as the shannon entropy of this probability distribution, i.e., we get the normalized permutation entropy by dividing the shannon entropy by lnd! the normalized permutation entropy lies between and . memory restrictions, and as staniek and lehnertz [ ] also state, one cannot have reliable statistics about the ordering dynamics. the embedding dimension is set to d = , but d = and d = are used for comparison purposes. the time delay τ , which is the time separation between symbols is set as τ = . we also search for the degree of correlational structure in the time series with the use of statistical complexity (lopez-ruiz et al. [ ] , lamberti et al. [ ] , rosso et al. [ ] ). a complexity measure developed is the so-called jensen-shannon complexity c js, which is a functional of the discrete distribution p of n probabilities associated with the time series (martin et al. [ ] ). it is a range of c js's values provided in the range of c min and c max given for an entropy value. once the jensen-shannon complexity normalized such as ≤ c js ≤ then where s is the shannon entropy, h[p] is the normalized shannon entropy and pe = { /n, . . . /n} is the uniform probability. the jensen-shannon complexity has been introduced in nonlinear dynamics analysis to detect essential details of the dynamics and discriminate different degrees of periodicity and chaos (lamberti et al. [ ] ). although the jensen-shannon complexity is widely used, another monoparametric generalization of the statistical complexity and normalized shannon entropy, based on the tsallis q entropy has been recently developed. we are able to produce a group of complexity measures and understand some of the different meanings of complexity, with the values of the parameter q in the tsallis entropy (ribeiro et al. [ ] , martin et al. [ ] ). therefore following the above works we attempt to create a series of q values that will help in constructing the so-called q-complexity entropy curve and we will compare the tsallis causality curve (h q [p] and c q [p]) with the jensen-shannon plane (h s [p] and c js [p]). the normalized tsallis entropy is given as for a full derivation of the normalized tsallis q and the associated complexity-entropy curve please see ribeiro et al. [ ] and martin et al. [ ] as well as rosso et al. [ ] which considers q = . for the jensen complexity measure c q [p], divergence and q are also calculated as the complexity for the tsallis entropy is calculated as where the disequilibrium q = jensen divergence * q . the the permutation entropy and the statistical complexity are calculated for embedding dimension d = and delay τ = , based on the b&p criterion that satisfies m ≫ d!. we also performed the analysis for two extra embedding dimensions d = and d = . the results seem to be independent of the embedding dimension selected for the symbolic reconstruction of the original time series, therefore we focus on d = . we start our analysis by presenting in fig. , panel (a) and (b), the shannon complexity-entropy causality plane (cecp) for all real estate indices in hong kong, partitioned by size and location. panel (a) presents the calculated quantifiers of the pre-crisis period based on size indices. all indices before the crisis appear to have higher permutation entropy and lower complexity value, than the quantifiers of the post-crisis period. in particular, prior to the crisis entropy and complexity values range from . to . and . to . and after the outbreak of the crisis, the quantifiers are . to . and . to . respectively. it can be concluded that the financial crisis has affected the dynamic structure of the indices, increasing their regularity and predictability. in terms of efficiency, which according to fama's sense means that the time series are random, the general index and the large and small/medium size flats indices show a lower efficiency level, during the post-crisis period, compared with the prior period. in other words, the results for the post-crisis period suggest that last week's price influence next week's price. panel (b), fig. , presents the analysis of the four sub-regions of hong kong, namely hong kong island, kowloon, new territories east, and new territories west. although most indices depict the same picture as the one with the size, where the after crisis period quantifiers exhibit lower permutation and higher complexity than with the pre crisis period, kowloon index behave much differently. based on the quantifiers, the index for the post-crisis period exhibits higher permutation and lower complexity than the pre-crisis period, signifying that the dynamical structure of the kowloon index is affected the opposite than the other indices. likely, the index was not affected by the crisis, evidently by the increased informational efficiency which by the way, is higher than the level before the crisis. a possible explanation of the apparent departure could be found on the following reasons. kowloon is a major part of the decentralized trend, due to hong kong island's high prices for office and retail space, and, also, a major recipient of strong demand for residential space manifestly by the major construction projects that took place, especially after the second half of the -decade. in order to show the robustness of the previous results we present in fig. the quantifiers of the shuffled data. please note that the quantifiers of the shuffled data are close to in terms of permutation and for statistical complexity, necessary conditions for a time series to be considered as a gaussian random process (white noise). according to fama's notion, this optimal combination ( , ) characterizes the strong form of the emh, where the market is strongly efficient reflecting both private and public available information. for the exact estimation of all quantifiers for each sub-period with embedding dimension d = and τ = are detailed in table . in order to compare the results, derived by the symbolic permutation entropy, with the hurst exponent h, we generate a time series with the use of the fractional brownian motion. as is well known, values of h = . means that the process is purely random while values of over . means that positive (or negative) steps are followed by positive (or negative) steps. if the value is less than . then a positive step is followed by a negative step and the opposite. thus, we perform the analysis of fractional brownian motions (fbms) using different hurst exponents. although there is a wide use of correlated stochastic processes for financial time series modeling, in our case, we generate numerical independent realizations of fbms with hurst exponent h ∈ { . , . , . , . , . , . , . , . , . , . , . , . }. the length of data is n = data points and we use the algorithm proposed by abry and sellan [ ] , and bardet et al. [ ] . the fbms generated curves are illustrated in fig. in both panels, along with the quantifiers from the permutation entropy method. the values of the entropy complexity plane as discussed before are very close to the ones obtained by fbms process, meaning that they share some similar dynamical properties. the h exponents of fbms are within the range of . - . , and few of them close to . , particularly for the pre-crisis period, a sign of uncorrelated dynamics. next we consider the tsallis q entropy and complexity, and present in fig. the q-complexity-entropy curve. using the fractional brownian motion, following hosking's procedure (hosking [ ] ) we apply various hurst exponents ( . , . , . . ., . ) for the embedding dimension d = and d = . the plots are average values from realizations of length time series of the entropy and complexity causality plane, with the parameter q ranging from q = + to q = with evenly spaced points between them. the d = and d = results of our real estate indices in fig. , panel (a) and (b) resemble those of the fractional brownian motion in the last two panels (c) and (d). all form loops with different size for the pre and after crisis period and the larger the value of h the broader the loop. since most of the indices behave similarly as the general index, we present only the general and the kowloon indices. more specifically, the general index depicted in fig. revealed broader loops for the after crisis period, while for the kowloon index, the loop for the after-crisis period is much smaller, for both d = and d = . except for the kowloon case, the results confirm the notion that during the outbreak of the crisis, the housing market indices exhibit larger hurst exponents. the dependence of q values on the hurst exponent is shown in fig. . as in ribeiro et al. [ ] , hurst exponent h = ( , . , . , . . ., ) is presented along with minimum value of the normalized entropy, as a function of q at q = q h , and the maximum value of the complexity as a function of q, when q = q c . fig. panel (a) shows for d = the positive correlation between q h and the hurst exponent, while in panel (b) the q c increases monotonically as h increases. panels (c) and (d) present the values of q the q = q h and q = q c for different embedding dimensions, i.e. d = , , . the extreme values q h and q c have similar trend, therefore we present only the general index. when d = , q h for both periods prior and after the crisis exhibit higher value followed by d = and d = , respectively. on the other hand, the values of q c are almost the same for both indices, regardless of the embedded d value. all q values optimizing h q and c q are presented in table . we now investigate the time evolution of the quantifiers in an attempt to test if the underlying process changes before and after the great recession. considering a weeks window, which corresponds to about business days (or two years) and shifting through the time series with a step of one week, we measure the time variation of both permutation entropy and statistical complexity. this methodology is utilized in order to detect changes in the underlying stochastic processes. for each index the sample size is divided into two periods, with the first spanning from to , and the second from to . fig. , presents the entropy complexity causality plane for both shannon and tsallis methods, with d = , for the general, new territories west and kowloon indices. although, both methods behave similarly, clearly, the entropy complexity causality plane discriminates between the two periods, as seen by the different locality of the points. for the calculation of the time evolution of the quantifiers, kullback-leibler and jensen-tsallis methods were used. since they offer similar results, we present the jensen-tsallis ones. for the first two indices, the after-crisis period show lower permutation entropy and higher statistical complexity, compared to the prior-crisis period, while the opposite emerges for the kowloon index. the kowloon index exhibits greater degree of randomness, since the outbreak of the crisis, consistent with a totally random stochastic process. lastly, kowloon index is one trend of its own. furthermore, all tsallis entropy results for each index for every q (q = . , . , . ) behave in the same pattern, therefore q = . is selected. both methods exhibit similar fluctuations in permutation entropy values. the results of the two methods confirm what we have observed in the previous fig. : before the crisis the entropy values are higher and around at the beginning of they start to fall significantly. the information efficiency, based on the quantifiers seems to decrease in value after the outbreak of the crisis, for most of the indices except the kowloon index. the upward trend of the informational efficiency, since the outbreak of the crisis could be explained firstly, on hong kong's government intention to transform kowloon into a second central business district (cbd). secondly, on the increasing inflow of investors' capital from mainland china to kowloon housing market, due to hedging against rmb depreciation (hui et al. [ ] ), and because they consider kowloon area as a strategic gateway. lastly, people are moving out of cbd of hong kong for less expensive real estate areas (cbre ). both permutation entropy approaches seem to capture well some particular incidents that took place during the period under investigation. the first event occurred few years before the crisis, on march and had to do with the socalled severe acute respiratory syndrome (sars) epidemic (lam et al. [ ] ). after the outbreak of the epidemic all indices declined in terms of permutation entropy value for more than two years. another event generating lower entropy value, magnifying the impact of the financial crisis was the resignation of five hong kong members of the parliament, in january , demanding more civil liberties. finally, the last decrease in permutation entropy values occurs in the first quarter of , where a special stamp duty on hong kong housing was imposed and the rating agencies announcement of the sovereign downgrade of nine european economies, (including france, austria, spain, and italy). in this paper we investigate the behavior of hong kong's housing market indices prior and after the u.s. financial crisis. based on normalized permutation entropy and statistical complexity we calculate the informational efficiency level. we found that the financial crisis modified the degree of randomness and the complexity of the housing indices. in all cases but one, the indices, measured in terms of size and region, exhibit lower permutation entropy and higher complexity, meaning that the financial crisis event affected the dynamical structure of the indices, increasing their regularity and predictability. but the kowloon index quantifiers exhibit higher permutation entropy value denoting greater informational efficiency or less regularity and loss of complexity. this outcome seems to be robust by utilizing the tsallis-q entropy methodology. in addition, by taking a -week long window, shifting through the time series with a step of one week, we calculate the time variation of the permutation entropy for representative indices. both, shannon and tsallis-q entropy methods display very similar trends and values. it seems that they capture well the impact of the financial meltdown on hong-kong's housing market indices, but with a small time delay. again, based on time variation the kowloon index depicts a different trend with the quantifiers to increase their values even during the outbreak of the crisis. lastly, the permutation entropy captures well the other major events such as the sars epidemic, the eurozone crisis and the resignation of the house representatives. efficient capital markets: a review of theory and empirical work efficient capital markets: ii a random walk down wall street on the impossibility of informationally efficient markets long-term dependence in stock returns measuring the degree of time varying market inefficiency long-term memories of developed and emerging markets: using the scaling analysis to characterize their stage of development hurst exponent and prediction based on weak-form efficient market hypothesis of stock markets a comparative analysis of the informational efficiency of the fixed income market in seven european countries theory of speculation toward a theory of marginally efficient markets forbidden patterns permutation entropy and stock market inefficiency complexity-entropy causality plane: a useful approach to quantify the stock market inefficiency on the efficiency of sovereign bond markets revisiting the european sovereign bonds with a permutation-information-theory approach complexity-entropy analysis of daily stream flow time series in the continental united states the (in)visible hand in the libor market: an information theory approach monitoring the informational efficiency of european corporate bond markets with dynamical permutation min-entropy crude oil market and geopolitical events: an analysis based on information-theory-based quantifiers market efficiency in foreign exchange markets the informational efficiency and the financial crashes is the us stock market becoming weakly efficient over time? evidence from -year-long data multiscale entropy analysis of crude oil price dynamics efficiency of crude oil markets: evidences from informational entropy analysis a spectral entropy method for distinguishing regular and irregular motion of hamiltonian systems characterization of time dynamical evolution of electroencephalographic epileptic records a review of symbolic analysis of experimental data randomizing nonlinear maps via symbolic dynamics permutation entropy: a natural complexity measure for time series electroencephalographic order pattern analysis for the separation of consciousness and unconsciousness parameter selection in permutation entropy for an electroencephalographic measure of isoflurane anesthetic drug effect permutation entropy of the electroencephalogram: a measure of anaesthetic drug effect using permutation entropy to measure the electroencephalographic effects of sevoflurane detecting dynamical changes in time series using the permutation entropy predictability analysis of absence seizures with permutation entropy permutation entropy to detect vigilance changes and preictal states from scalp eeg in epileptic patients. a preliminary study permutation entropy and statistical complexity analysis of turbulence in laboratory plasmas and the solar wind a statistical measure of complexity parameter selection for permutation entropy measurements intensive entropic non-triviality measure distinguishing noise from chaos generalized statistical complexity measures: geometrical and analytical properties characterization of time series via rényi complexity-entropy curves characterizing time series via complexity-entropy curves the wavelet-based synthesis for fractional brownian motion proposed by f. sellan and y. meyer: remarks and fast implementation generators of long-range dependence processes: a survey modeling persistence in hydrological time series using fractional differencing speculative bubbles in mass and luxury properties: an investigation of the hong kong residential market an artificial neural network and entropy model for residential property price forecasting in hong kong we would like to acknowledge the careful work and constructive criticism of the referees. key: cord- -ltil hwl authors: cheng, cecilia; tang, catherine so‐kum title: the psychology behind the masks: psychological responses to the severe acute respiratory syndrome outbreak in different regions date: - - journal: asian j soc psychol doi: . /j. - x. . .x sha: doc_id: cord_uid: ltil hwl severe acute respiratory syndrome (sars) was first reported in china, and spread to regions, affecting over people worldwide. for the general public, the psychological impact of sars may have been greater than the physical health danger of the disease. the present paper proposes the influence of psychological factors on people's cognitive, affective, and behavioral responses during the sars outbreak. the various papers in this special issue of the journal reveal how people have reacted during the sars outbreak: people's general coping styles may be related to their health behavior during the outbreak. cultural differences were evident in the perception of sars, and individuals’ perceptual styles may have influenced their ability to cope with the outbreak. the way in which individuals coped with sars‐related stressful events was different from their usual practices of managing daily stress. individual differences in the adoption of preventive measures were related to the distinct susceptibility to several social‐cognitive biases. then spread to east asia, and further to canada and other parts of the world. the virus was reported in areas and affected over people, with more than deaths. the unknown nature of the virus immediately encouraged researchers to unveil its biomedical mechanisms. the epidemiological, laboratory, radiological, and clinical features of sars were published shortly after the onset of the outbreak (drosten et al ., ; lee et al ., ; tsang et al ., ; wong et al ., ) . the most important finding was that a new coronavirus, unlike any known member of the genus coronavirus, was the major causative agent of the disease. however, during the sars outbreak, there may have been two diseases looming. in addition to the actual physical health danger posed by sars, a new psychological problem appeared. this problem can be termed 'sars phobia' (cheng c., in press ). on april , a hoaxer in hong kong caused public panic by hijacking a major newspaper website and posting a bogus news item, which claimed that hong kong would soon be declared a sarsinfected region and sealed off from the rest of the world. this news quickly spread around the city, causing panic-stricken people to mob stores to buy necessities. on april , a -year-old man from taiwan who suspected that his family members had contracted sars committed suicide in a hospital ward. in canada, although less than canadians died of sars, a significantly greater portion of people were affected by the psychological effects of the disease (carr, ) . moreover, the psychological anxiety and hype related to sars even led some people to claim that sars was to the chinese what the september tragedy was to the americans (einhorn, ) . this analogy was based on the sudden occurrence of the incidents, both of which caused a considerable number of deaths and economic turmoil in the affected regions. the worldwide impact of the sars outbreak has also been compared to that of the flu pandemic that killed million people, and to the current hiv crisis (british broadcasting corporation, ) . this suggests that the fear of sars has become a more severe pandemic than the disease itself (world health organization, ) . the disease has been widely publicized as 'fatal pneumonia', 'lethal pneumonia' and 'killer pneumonia' by the media. the life-threatening aspect of sars was vividly described and frequently brought to people's minds. according to the availability heuristics (tversky & kahneman, , , an individual's judgment of the likelihood of an event is biased by the ease of recall from memory. consistent with this heuristic, a population survey conducted in hong kong in early april (lam et al ., ) revealed that about % of the respondents believed that the probability of contracting sars was greater than that of contracting a common cold and dying from a traffic accident. this perception seems to have been irrational and biased, which may be attributable to the dearth of information regarding the causes, modes of transmission, and methods of treatment of this novel virus. the dearth of information allows individuals to interpret the disease in an idiosyncratic manner. to cope with this health threat, governments in many regions introduced a number of strategies, such as health declarations at immigration checkpoints and setting up quarantine systems. publicity campaigns were launched to inform the public about the disease (see the websites of the department of health, hong kong; ministry of health, singapore; and health canada). apart from providing more information about sars, the campaigns also included the dissemination of information about precautionary measures, such as urging people to wear face masks, to pay more attention to personal hygiene, to build up physical health, and to see a doctor if they had pneumonia-or influenza-like symptoms. people in sars-affected regions adopted precautionary measures. the most common included wearing face masks on the street and at work, seeking information and monitoring up-to-date news about sars, and avoiding crowded areas. individuals differ considerably in the type and extent of preventive measures undertaken. psychologists were quickly aware that psychological factors played a role in the sars outbreak, and were interested in a number of important questions. could the current knowledge yielded from coping research help in the understanding of people's attempts to handle the sars outbreak? because sars affected a number of regions, including people from both asian and western cultures, did individuals from different cultures perceive and cope with the crisis in distinct manners? did people attempt to handle the sars epidemic in ways that were similar to those with which they attempt to handle stressful daily events? to cope with the outbreak, why did some people engage in preventive health behavior while others ignore the use of preventive measures? this special issue of the journal, 'the psychology of sars', is devoted to answering these questions by exploring the psychological impact on people all over the world, especially the hard-hit regions of china, hong kong, singapore and canada. the studies herein unveil how individuals from different parts of the world perceived and attempted to cope with this life-threatening virus. these issues are addressed from a variety of perspectives, including the cognitive-behavioral, motivational, social-cognitive, and cultural perspectives. lee-baggley, delongis, greenglass, and voorhoeave explore the relationships between strategy deployment and sars-related health behavior. their online questionnaire assessed global coping strategies and specific health behavior in response to the sars outbreak. the participants were from different walks of life, and most of them were from regions that were not affected by sars. the findings revealed that participants who tended to use wishful thinking were more likely to avoid going to public areas and avoid people who they believed to be affected by sars. those who tended to adopt empathic responses were more likely to undertake measures to prevent sars, such as wearing face masks and exercising regularly. these results suggest a link between general coping strategies and specific health behavior to avoid contracting sars, which applies to people in areas that were and were not affected by sars. ji, zhang, usborne, and guan examine cross-cultural differences in optimistic thinking between the chinese and european canadians during the sars outbreak. the participants were recruited from beijing and toronto, and the two samples demonstrated unrealistic optimism, that is, the perception of oneself as less likely than an average person to contract sars. compared to their canadian counterparts, the chinese participants showed greater unrealistic optimism when estimating their own risks of being infected, but took more preventive measures. the authors concluded that the chinese dialectical thinking style may have promoted the belief that both negative consequences and positive changes could coexist during the sars crisis. this belief may have propelled the chinese to think about their future in a more positive light, and enhance their motivation to adopt a preventive approach to cope with the crisis. chang and sivam also examine how cultural factors influenced perception and coping tendencies in the context of sars. they explored whether heritage values were related to sars-related fears, defensive pessimism, and preventive measures in a sample of singaporeans. their results revealed positive associations among all of the psychological variables assessed in the study. specifically, compared to singaporean participants who endorsed fewer of the chinese values (i.e. prudence, industry, and civic harmony), those with a greater tendency to adopt these values were characterized by higher levels of sars-related fears, greater defensive pessimism, the adoption of more health behaviors, and the experience of more adverse outcomes related to the outbreak. the implication is that cultural factors are important to psychological research on sars. gan, liu, and zhang compare how beijing university students handled the sars epidemic with how they handled stressful daily events. for these two types of stressful situations, they examined the participants' flexibility in cognitive and coping responses across a diversity of events. the participants tended to distinguish among different stressful daily events in the extent of controllability, and deployed more problem-focused coping to handle daily stressors with controllable outcomes. however, they tended to perceive most sarsrelated stressful events as uncontrollable, and used more emotion-focused coping to handle such events. these findings indicate that individuals had a propensity to be less flexible, both cognitively and behaviorally, in their attempts to handle the sars epidemic than in their usual practice of handling stress. based on these findings, the authors proposed that encountering an unknown but contagious disease may hamper individuals' ability to: (i) distinguish among the characteristics of events related to the disease; and (ii) respond flexibly to meet the specific demands of distinct events. tam, lau, and chiu examine two samples of hong kong high school students in terms of social-cognitive biases after the sars outbreak. they found that compared to those who practiced sars preventive behavior (i.e. the practicers), those who did not (i.e. the nonpracticers) were more prone to two types of social-cognitive biases: false consensus bias and the actor-observer bias. to elaborate, the non-practicers tended to underestimate the prevalence and importance of prosocial concerns in the preventive behavior that was commonly adopted by practicers during the outbreak. these findings shed light on how hong kong adolescents evaluated prevailing norms and their own motives in the prevention of an emerging epidemic. the authors pointed out that non-practicers of health behavior may believe that their behavioral pattern is widely shared and acceptable in the community, and may thus be less motivated to change their behavior. finally, cheung contributes an insightful commentary on the importance of psychological factors to the sars epidemic. the strengths and limitations of the five aforementioned studies are discussed. cheung concludes by advocating the extension of the biopsychosocial model to the context of sars. this commentary, together with the five articles, provides valuable information on the ways in which people from different regions of the world responded affectively, cognitively, and behaviorally to the sars outbreak. this information may be useful not only for enhancing the understanding of the psychological impact of sars, but, more importantly, for designing preventive workshops for the general public and intervention programs for people who have contracted sars and their family members. in conclusion, this special issue highlights the role of psychological factors in people's cognitive and behavioral responses to the sars outbreak. the impact of psychological factors may even have had a greater impact than the virus itself. the articles in this issue may contribute to the identification of possible psychological mechanisms entailed in the interaction among the virus, people, and the social-cultural milieu. apart from biomedical studies, psychological studies and cross-cultural studies are also instructive in fostering the understanding of sars. the sars epidemic alerted the world that public health is no longer a local issue. in this era of globalization, not only people and information but also viruses flow freely without borders. the treatment and prevention of novel, unknown diseases require the joint effort of government bodies and health-care professionals from various countries. it is hoped that lessons can be learnt, and awareness of the possible psychological impact of sars on the general public can be increased. should sars return in the future, fears will be kept in perspective, social-cognitive biases will be minimized, and effective preventive measures will be undertaken if we know more about the psychology of sars. sars: is global panic justified? bbc news psychological toll of sars greater than physical toll, psychologist says to be paranoid is the standard? panic responses to the sars outbreak in the hong kong special administrative region identification of a novel coronavirus in patients with severe acute respiratory syndrome where sars stands on the disaster scale public perceptions and preventive measures of hong kong citizens concerning atypical (coronavirus) pneumonia a major outbreak of severe acute respiratory syndrome in hong kong a cluster of cases of severe acute respiratory syndrome in hong kong availability: a heuristic for judging frequency and probability judgment under uncertainty: heuristics and biases haematological manifestations in patients with severe acute respiratory syndrome: retrospective analysis severe acute respiratory syndrome (sars): status of the outbreak and lessons for the immediate future the authors would like to thank the contribution of francis cheung as the managing editor of this issue of the journal. key: cord- -jaaqvzfd authors: lau, joseph t.f.; kim, jean h.; tsui, hiyi; griffiths, sian title: perceptions related to human avian influenza and their associations with anticipated psychological and behavioral responses at the onset of outbreak in the hong kong chinese general population date: - - journal: american journal of infection control doi: . /j.ajic. . . sha: doc_id: cord_uid: jaaqvzfd background anticipated psychological responses and perceptions of risk have not been examined prior to the outbreak of an epidemic. methods using a cross-sectional, telephone survey, chinese adults in hong kong were interviewed anonymously in november, to examine beliefs related to h n avian influenza and anticipated responses. results of respondents, . % and . %, respectively, believed that bird-to-human or human-to-human h n transmission would occur in the next year. in the event of a bird-to-human or human-to-human outbreak in hong kong, many anticipated high fatality rates ( . % and . %, respectively), permanent physical damage ( . % and . %, respectively), inadequate vaccines ( . % and . %, respectively), insufficient medicine supplies ( . % and . %, respectively), inadequate hospital infection control ( . % and . %, respectively), high susceptibility of family members contracting h n ( . % and . %, respectively), and impact on oneself/family worse than those of severe acute respiratory syndrome ( . and . %, respectively). most anticipated at least of the studied stress-related responses (e.g., panic) or the adoption of at least of the studied preventive behavioral measures (e.g., avoiding going out). conclusion panic and interruption of daily routines may occur in the event of a human avian influenza outbreak. dissemination of accurate, timely information would reduce unnecessary distress and unwanted behaviors. perceptions related to human avian influenza and their associations with anticipated psychological and behavioral responses at the onset of outbreak in the hong kong chinese general population introduction it is widely anticipated that a global h n avian influenza pandemic will occur in the near future. high pathogenesis and fatality are expected, and some experts have estimated that there could be as many as . million deaths. from january until february , , laboratory confirmed cases and deaths from bird-to-human transmissions were reported in countries. there are frequent, detailed reports in the media about this newly emerging infection, and people may be forming and rapidly changing their perceptions about this disease in the absence of complete knowledge, as seen in the severe acute respiratory syndrome (sars) epidemic. concerning human avian influenza, given the high fatality rate, the number of countries being affected, as well the sars experience, it is expected that an outbreak of the disease would result in a high level of psychological distress in the affected communities. human avian influenza preparedness needs to include the understanding and monitoring of diseaserelated perceptions and psychological responses. during the sars epidemic, such perceptions affected the practice of public health behaviors such as frequent hand-washing and the wearing of face masks, which, in turn, contributed to the control of the epidemic. , a high level of distress due to sars was documented in the community, which was associated with sarsrelated perceptions and public health behaviors; this underscores the need for psychological preparedness. this study investigated the prevalence of perceptions related to human h n avian influenza, anticipated psychological responses, and anticipated avoidance behaviors in the event of a local outbreak (i.e., if - new human cases of h n were to be reported in hong kong). factors that are associated with these anticipated psychological and behavioral responses were investigated. in this study, psychological and behavioral responses to human avian influenza were in reference to two situations: the onset of birdto-human outbreaks and the onset of human-tohuman outbreaks (measurements). the study population consisted of hong kong chinese adults aged to years. an anonymous cross-sectional telephone survey, using a structured questionnaire, was conducted in november of (n ). random telephone numbers were selected from up-to-date telephone directories. telephone calls were made by trained interviewers in the evening (from : pm to : pm) to avoid overrepresentation of unemployed persons. for unanswered calls, at least other independent calls were made before considering the number to be invalid. similar methods have been used in several studies on sars as well as a study on avian influenza. , the household member whose birthday was closest to the date of the interview was invited to join the study. verbal informed consent was obtained from the respondents and ethics approval was obtained from the ethics committee of the chinese university of hong kong. the response rate, defined as the number of completed interviews divided by the number of eligible households, was approximately %. financial support was provided by the school of public health of the chinese university of hong kong and institutional review was conducted by the chinese university. background variables were measured. respondents were asked ( ) about their level of emotional distress during the sars epidemic on a scale ranging from (not at all) to (extremely distressed); ( ) whether they avoided visiting hospitals in the last months for fear of contracting avian influenza; ( ) whether they had been eating less poultry meat in the last months; and ( ) whether they anticipated birdto-bird, bird-to-human, and human-to-human h n outbreaks to occur in hong kong, in mainland china, or in other places in the next months. respondents were asked their perceptions about anticipated bird-to-human h n outbreak in hong kong, including medical-related perceptions (perceived fatality, physical harm to patients, whether symptoms would be similar to those of sars); preparedness of the local health authorities (adequacy of vaccines, medicine for treatment, and hospital infection control); susceptibility of one's family members to avian influenza infection; and comparisons between consequences of an anticipated avian influenza epidemic with those of the sars epidemic (in terms of infectivity, impact on oneself and his/her family, economic impacts, duration of the epidemic, and total number of people affected). anticipated psychological distress from human avian influenza at an onset of bird-to-human h n transmission (if - new human cases were to be reported) in hong kong was assessed by items, including whether the respondent would worry much about oneself or one's family members contracting the virus, be in a panic, be very upset, become very emotionally disturbed, face large impacts on one's daily life, and lack confidence in protecting oneself or one's family from contracting the virus. avoidance behaviors that were examined included avoidance of hospitals, crowded places, going out, and going abroad, and the likelihood of not sending their children to school. the above-mentioned perceptions and psychological/behavioral items related to bird-to-human h n transmission in hong kong were asked only to a subset of all respondents (n ). for the rest of the respondents (n ), the same items were asked in the context of an anticipated human-to-human h n outbreak in hong kong to keep the study instrument at a reasonable length for a telephone interview. test-retest reliability has not been established. anticipated occurrence of the types of h n transmission in the next months in hong kong was tabulated by different socio-demographic factors. corresponding perceptions and anticipated psychological and behavioral responses related to bird-to-human and human-to-human h n transmissions were compared by multivariate odds ratios (ors), adjusting for socio-demographic factors (age, gender, educational level, marital status, employment status). univariate ors of factors in association with psychological and behavioral responses were presented. univariately significant variables were used as candidates for multivariate logistic regression models. we used spss for windows (version . ), and a p-value of ,. was considered to be statistically significant. the socio-demographic characteristics of the respondents are summarized in table . of all respondents, . % said that they had avoided visiting hospitals because of a fear of contracting avian influenza, and . % reported they had been eating less poultry in the last months (table ) . most of the respondents ( %) expected that birdto-bird h n outbreaks would occur in the coming year (table ). corresponding figures were . % for bird-to-human h n outbreaks (in hong kong, . %; mainland china, . %; other places, . %) and . % for human-to-human h n outbreaks (in hong kong, . %; mainland china, . %; other places, . %). those who were younger, better educated, and never married were more likely to anticipate birdto-bird, bird-to-human, or human-to-human h n outbreaks occurring in some locale in the next months (education level was not associated with anticipated occurrence of human-to-human h n outbreaks in some locale in the next months) ( table ) . similar perceived high fatality rates were observed in the scenarios of bird-to-human and humanto-human h n transmission ( . % and . %, respectively) ( table ) . perceived permanent physical damage and perceived similarity between symptoms of human avian influenza and sars are reported in table . of the respondents, . % to . % believed that local health authorities would not be adequately prepared in aspects (vaccine, availability of medicine, control of nosocomial infection) in an anticipated local bird-to-human h n outbreak. similar figures ( . %- . %) were obtained with respect to control of a local human-to-human h n outbreak (table ) . of the respondents, . % and . %, respectively, perceived high or very high susceptibility for their family members to contract the virus at the onset of a human-to-human h n outbreak or at the onset of a bird-to-human h n outbreak in hong kong. in the case of a local human-to-human h n outbreak, respondents tended to believe that local health authorities were less prepared (adjusted or range, . - . ), and that their family members were highly susceptible (adjusted or, . ; table ), as compared with a local bird-to-human h n outbreak. high percentages of respondents believed that a human-to-human h n outbreak in hong kong would be worse than the past sars experience in hong kong in terms of infectivity, impact on respondents were asked to rate their level of emotional distress during the sars epidemic on a - point scale. a higher score denotes a higher level of emotional distress and the th percentile is . oneself/family and on the economy of hong kong, duration of the pandemic, and total number of people affected ( . %- . %; table ). the differences in the prevalence of perceptions with respect to birdto-human versus human-to-human h n outbreaks in hong kong were statistically significant for a number of affected persons and local economic impacts (table ) . more respondents would worry about themselves or their family members being affected by h n at a human-to-human h n outbreak ( . % and . % respectively), as compared with a bird-to-human h n outbreak ( . % and . % respectively) ( table ). similar trends were observed for perceived large impact on daily life ( . % versus . %) and panic ( . % versus . %). of the respondents, . % and . %, respectively, would expect to have at least one of the items indicating distress (or, . ; p , . ; table ). the prevalence of anticipated avoidance behaviors relating to the scenarios of human h n outbreaks (bird-to-human versus human-to-human) transmission were, however, not significantly different from each other (table ). in either case, more than % of respondents would avoid visiting hospitals, crowded places, going out, or going abroad, and close to % would not allow their children to go to school (table ) . the multivariate results (table ) showed that those who felt much emotional distress (. th percentile) during the sars epidemic (or, . ), and those who were eating less poultry in the last months (or, . ), believed that human-to-human h n transmission would occur in the coming year (or, . ), perceived that their family members would be highly susceptible to contracting the human-to-human h n virus (or, . ), believed that hong kong would not have adequate medicine for treatment at the time of a human-to-human outbreak (or, . ), and perceived that there would be a larger impact on oneself and family members as compared with their sars experience (or, . ). these individuals also were more likely to anticipate a higher level of psychological distress (i.e., showing or more responses that are associated with distress, table ) if to new cases of human-to-human h n transmission were to be reported in hong kong (table ) . several variables were significant only in the univariate analysis (table ) . for the scenario of an anticipated local bird-tohuman h n outbreak, the multivariate results (table ) showed that those who had avoided visiting hospitals in the last months (or, . ), ate less poultry in the last months (or, . ), perceived their family to be highly susceptible to contracting h n (or, . ), believed that bird-to-human avian influenza would cause serious permanent physical damage (or, . ), perceived that bird-to-human avian influenza would have symptoms similar to those of sars (or, . ), and perceived that the bird-to-human avian influenza epidemic would have a worse economic impact on hong kong as compared with sars (or, . ) would be more likely to anticipate a higher level of distress at the onset of a bird-to-human transmitted h n outbreak in hong kong. some variables that were significant in the univariate analysis were not significant in the multivariate analysis (table ). the multivariate results showed that those who were older (or, . ), felt highly emotionally distressed (. th percentile) during the sars epidemic (or, . ), had avoided visiting hospitals because of avian influenza in the last months (or, . ), were eating less poultry in the last months (or, . ), perceived that h n would have a very high fatality (or, . ), or perceived that avian influenza would have larger impacts on oneself and family as compared with sars (or . ) were more likely to anticipate practicing more avoidance behaviors (i.e., . of the studied avoidance behaviors) if to new cases of human-tohuman h n transmission were to be reported in hong kong (table ) . concerning an anticipated onset of a local birdto-human h n outbreak, similar multivariate results showed that those who had avoided visiting hospitals (or, . ), those who believed that the bird-tohuman h n would have very high fatality (or, . ), or that the bird-to-human h n would have higher infectivity than did sars (or, . ) would be more likely to anticipate practicing more avoidance behaviors (i.e., . of the studied avoidance behaviors) ( table ). high levels of panic and distress in the general public were reported during and after the sars epidemic. , the fact that over one-half of the population anticipated a bird-to-human transmission in hong kong and that a large percentage of the local population reported that they would practice many avoidance behaviors in the event of an epidemic both suggest that it is likely that any human h n outbreak would cause a very high level of psychological distress, even at the initial stages. anxiety is expected to be greater if to new cases of human-to-human transmission are reported, as compared with the reporting of to new bird-to-human transmission cases in hong kong. during a local full-blown human avian flu outbreak, the level of psychological distress would be much higher than those just described. fear of the unknown may be a common feature of newly emerging infectious diseases. therefore, the government should take steps to prevent general panic in the public from occurring. similar results to those reported in studies of stress and quality of life during the sars epidemic were found, and the perceived chance of one's family members contracting avian influenza also was associated with anticipated distress. therefore, family counseling and psychological support would be an essential part of the response to an epidemic. implicit comparisons between human avian influenza and sars may have been made by many respondents, because more than % of the respondents believed that sars and human avian influenza have similar symptoms. the level of distress experienced during the sars epidemic was associated significantly with anticipated distress and avoidance behaviors. the sars epidemic caused tremendous damage to hong kong's population and many individuals exhibited posttraumatic stress symptoms. , hence, human avian influenza may elicit recollections of the respondent's painful sars-related experience, which may elevate the perceived level of distress that is due to human avian influenza. therefore, particular attention must be given to those who were affected greatly by the sars epidemics (e.g., patients, health care workers). most of the respondents anticipated that outbreaks of bird-to-human h n would occur in some locale in the next year, but they were split in anticipating whether human-to-human h n outbreaks would occur in the next year. fewer respondents believed that such outbreaks would occur in hong kong than in mainland china and other countries, possibly because no h n cases had been reported in birds or in humans in hong kong from march until the time of the survey (november ). more people may anticipate human-to-human h n outbreaks in hong kong in the near future because birds that are infected with h n have been reported continuously in hong kong since january . therefore, another surveillance study is warranted. those who anticipated a human-to-human h n outbreak in some locale in the coming year also were more likely to perceive higher levels of distress with the onset of a local human-to-human h n outbreak. with the likelihood of a pandemic, the level of distress in a community cannot be determined by local factors only; panic in other countries may start a chain reaction. international efforts to reduce panic are respondents were asked to rate their level of emotional distress during the sars epidemic on a - point scale. a higher score denotes a higher level of emotional distress and the th percentile is . ; . , p , . . *p , . . **p , . . ***p , . . z anticipated psychological distress responses listed in table . warranted. in , humans who were affected by h n had been reported in hong kong, but not in other countries. according to our observations, not much distress seemed to exist in the public in hong kong, although this was not documented. therefore, it is argued that whether a newly emerging infectious disease results in distress in the public depends on external factors (e.g., whether other countries are being affected) and local factors, such as experience with other diseases (e.g., sars). human avian influenza was seen by many respondents to result in serious medical consequences that are in line with its high reported fatality. it is interesting to see that even before the onset of a newly emerging infectious disease (in our case, human avian influenza), people may be changing their behaviors (e.g., avoiding visiting hospitals because of fear of contracting avian influenza infection and eating less poultry meat). this study showed that such behavioral changes were associated significantly with anticipated distress and anticipated avoidance behaviors. with the onset of a human avian influenza outbreak in hong kong, more than % would adopt at least out of the avoidance behaviors studied. there is little doubt that the local economy would be affected, even at the onset stage of a local human influenza epidemic. it is likely that the level of distress would be enhanced in a vicious cycle, as seen in the sars epidemic. , respondents were asked to rate their level of emotional distress during the sars epidemic on a - point scale. a higher score denotes a higher level of emotional distress and the th percentile is . ; . , p , . . *p , . . **p , . . ***p , . . z anticipated avoidance behaviors listed in table . despite efforts made by the government, the respondents were not convinced that the local authorities are well-prepared for a human h n epidemic. these beliefs also were associated with perceived distress and avoidance behaviors. the government needs to reassure the public continually about its preparedness, and to take behavioral and psychological community responses into account. although most key daily societal operations in hong kong and in other countries were maintained during the sars epidemic, this could not be taken for granted in a full-scale human avian influenza epidemic, in view of the perceived high fatality and infectivity. there are areas of doubt-for example, whether health care workers and other frontline workers who have to work closely with affected patients will comply with their job instructions-as was found in the sars epidemic. a study of this topic is warranted. emergency plans and rehearsals need to be prepared by the government to deal with crisis, because there is a chance that some essential services may break down. the current governmental plans seem to be confined to vaccination, treatment, social distancing, and infection control, assuming all mechanisms will run smoothly. psychological preparedness in the general population and in different social groups (e.g., health care workers) may have been overlooked. timely dissemination of accurate information may reduce unnecessary panic. this may be the first essential step in promoting psychological preparedness within the community. this study has several limitations. first, it was conducted using telephone surveys and some households may not have been included. in hong kong, however, almost all households have telephones and a large number of local published studies on sars - or avian influenza , have used this method. because the attitudes and perceptions measured may change over time, especially when circumstances changes (e.g., reporting of new infection), telephone surveys have the advantage-over household surveys-of collecting data within a short period of time. the response rates of both types of surveys are comparable in the local setting. second, the response rate of the study was not high. again, the response rate was similar to many of the other local studies that have been published, , with the distributions of -to -year-old and -to -year-old age groups being comparable to those obtained from the census data ( . % and . %, respectively). when we asked about the perceived adequacy of vaccine, we used the term ''vaccine'' and did not specify what type of vaccine, because an h n vaccine is not available. this is assessing the subjective perception of a hypothetical situation in the future, and the way of asking should be acceptable. the gender distributions ( . % male and . % female) also were comparable to the census distributions ( . % male and . % female). adoption of behavioral responses was self-reported and had not been validated. test-retest reliability was not established; however, during this preoutbreak stage, it is unlikely that social desirability strongly biased the reporting of these behaviors. recall bias also is unlikely to be significant because of the short recall period of to months. in summary, high proportions of respondents anticipated that bird-to-human and human-to-human h n outbreaks would occur in hong kong or in some other locale in the coming year. it is very likely that even at the onset of a human avian influenza epidemicregardless of whether it is a bird-to-human or humanto-human transmission-widespread distress, panic, and avoidance behaviors would occur in hong kong as well as in the other affected countries. it is very likely that the economy and daily life in the affected societies will be affected severely. because a pandemic may occur, the level of distress may be worse than that during the sars epidemic. therefore, psychological preparedness in the community is essential; however, caution should be exercised in extrapolating the observed results to other countries because hong kong has its own unique sars experience. other countries that are concerned about avian influenza should carry out their own assessment and surveillance on the potential impact of avian influenza. the government should proactively reassure the public about its preparedness and include provision of family psychological counseling services and emergency plans to deal with any crisis situation. surveillance of perceptions and responses of the general public also should become a regular part of the preparatory plans. funding for this study was provided by li ka shing institute of health sciences. world health organization. ten things you need to know about pandemic influenza confirmed human cases of avian influenza a(h n ) monitoring community responses to the sars epidemic in hong kong: from day to day sars-related perceptions in hong kong sars transmission, risk factors, and prevention in hong kong avian influenza risk perception positive mental healthrelated impacts of the sars epidemic on the general public in hong kong and their associations with other negative impacts british broadcasting corporation. sars Ôcould cost asia $ bn centre for health promotion. hong kong's preparedness for influenza pandemic-prevention and protection prevalence of common chronic pain in hong kong adults perceptions about status and modes of h n transmission and associations with immediate behavioral responses in the hong kong general population discriminatory attitudes towards people living with hiv/aids and associated factors: a population based study in the chinese general population population by age group and sex key: cord- -b un authors: chan, sophia s.c.; so, winnie k.w.; wong, david c.n.; lee, angel c.k.; tiwari, agnes title: improving older adults’ knowledge and practice of preventive measures through a telephone health education during the sars epidemic in hong kong: a pilot study date: - - journal: international journal of nursing studies doi: . /j.ijnurstu. . . sha: doc_id: cord_uid: b un abstract background the outbreak of severe acute respiratory syndrome (sars) in hong kong posed many challenges for health promotion activities among a group of older adults with low socio-economic status (ses). with concerns that this vulnerable group could be at higher risk of contracting the disease or spreading it to others, the implementation of health promotion activities appropriate to this group was considered to be essential during the epidemic. objectives to assess the effectiveness of delivering a telephone health education programme dealing with anxiety levels, and knowledge and practice of measures to prevent transmission of sars among a group of older adults with low ses. design pretest/posttest design. settings subjects were recruited from registered members of a government subsidized social service center in hong kong and living in low-cost housing estates. participants the eligibility criteria were: ( ) aged or above; ( ) able to speak cantonese; ( ) no hearing impairment, and ( ) reachable by telephone. of the eligible subjects, older adults completed the whole study. methods the interviewers approached all eligible subjects by telephone during the period of – may . after obtaining the participants’ verbal consent, the interviewer collected baseline data by use of a questionnaire and implemented a health education programme. a follow-up telephone call was made a week later using the same questionnaire. results the level of anxiety was lowered (t= . , p< . ), and knowledge regarding the transmission routes of droplets (p< . ) and urine and feaces (p< . ) were improved after the intervention. although statistical significant difference was found in the practice of identified preventive measures before and after intervention, influence on behavioral changes needed further exploration. conclusion the telephone health education seemed to be effective in relieving anxiety and improving knowledge of the main transmission routes of sars in this group, but not the practice of preventing sars. telephone contact appears to be a practical way of providing health education to vulnerable groups when face-to-face measure is not feasible and may be useful in raising health awareness during future outbreaks of emerging infections. empirical evidence on the effectiveness of telephone health education among older adults with minimal or no formal education is lacking. low health literacy among the older adults may hinder understanding of mass health education against sars, which might be essential for effecting behavioral change. telephone counseling could be an effective means in improving health knowledge by providing individual counseling on health behaviors and social support among older adults who lives alone. this is the first systematic study to assess the effectiveness of delivering telephone health education to older adults during the outbreak of sars in hong kong. the findings of the study added some knowledge on feasibility and effectiveness of providing telephone intervention for older adults during an infectious disease epidemic, thus enlightened its applicability in possible pandemics such as avian and other influenzas telephone health education is a safe measure to provide health education when face-to-face measures are not feasible during outbreaks of infection. the aging population is growing in hong kong, as it is elsewhere. in hong kong, an adult aged or above is considered as an older adult because of the lowering age of retirement (neugarten, ) , with approximately . % (n ¼ , , ) of the total population aged years or above (hong kong census and statistic department (hkcsd), december ) . unlike other demographic groups in hong kong, literacy rates are low in this group with more than . % not having undertaken any formal education. among those who have undertaken some formal education, . % completed primary schooling only (hkcsd, october ) . in other words, only a small proportion of older adults in hong kong are educated above primary level. this situation presents many challenges for health promotion and disease prevention activities, as many of the usual methods of disseminating health information are not appropriate for this population. such challenges were particularly noticeable during the outbreak of severe acute respiratory syndrome (sars) (february-june ) in hong kong. over the course of the outbreak, cases were reported with deaths. adults years of age or older were . % of the sars cases (hksarsec, ) ; however, the age-specific mortality rate for this age demographic was about . % (leung et al., ) . the hong kong government launched a campaign to keep the city healthy and clean. measures to prevent the transmission of sars related to personal hygiene and environmental sanitation were publicized daily in the media as a way to minimize infection. however, the presence of functional impairments resulting from chronic illness or knowledge deficits due to low literacy levels among the older adults may affect their understanding and perceived relevance to habitual hygiene practice. their compliance to recommended infection control measures may be low. thus, more concern about older adults especially those living alone was expressed by health care providers and in the media (kong, ) . the non-compliance to health measures among this susceptible group could pose higher risks for contracting sars and transmitting the virus to others once becoming a carrier. in view of this challenge, an alternative means to provide health education and support for them was considered essential to ensure the effectiveness of communicating the necessary health messages to this vulnerable group, especially during the outbreak of sars. according to the world health organization (who, n.d.), e-health refers to the use of electronic means into the practice of protecting and promoting health. it can help provide health information and services to the public who have difficulty in accessing healthcare institutions due to physical illness, insufficient resources, environmental constraints or other reasons. e-health relies on a variety of technologies ranging from simple systems (e.g., telephone, facsimile machines) to complex systems (e.g., satellite links, and integrated services digital network). among various types of technologies, the telephone can offer an inexpensive, convenient and simple method of delivery for health information, education and psychosocial support for older adults at home (blixen et al., ; hiltunen et al., ) . ninetythree percent of the population have a telephone at home (hong kong office of telecommunications authority, , january ) and it is also considered to be a safe measure of communication during the sars epidemic. several studies have indicated that telephone contacts can have a positive effect on various health promotion or disease prevention programmes (hull et al., ; zhu et al., ) . hull et al. ( ) examined the effect of telephone appointments for influenza immunization at a nurse-run clinic for older adults in the united kingdom. they found that the uptake of immunization among the older adults was boosted by % using telephone appointment. zhu et al. ( ) investigated the effectiveness of a telephone quit smoking service for about participants in the usa. using a randomized controlled trial design, they found that the rates of smoking abstinence for the intervention group were significantly higher than for the control group (po . ). similar results regarding telephone counseling for smoking cessation (stead et al., ) , attitude towards current treatment (theiler et al., ) , knowledge on disease (branch et al., ) and prescribed regular medications (ayanian et al., ) were also reported. although not all literature supports the positive effects of telephone education on health promotion activities (gallagher et al., ; stoddard et al., ) , for the purposes of this study, it was considered to be a cost-effective means of communication, and safe for both older adults and interviewers under the spirit of minimal contact during the sars epidemic. a group of faculty and nursing students of a university in hong kong therefore implemented a telephone health promotion programme for a group of older adults. the aims of the study were: ( ) to assess the baseline data of older adults regarding their level of anxiety, knowledge of the main transmission routes of sars, and measures taken to prevent the transmission of sars. ( ) to provide older adults with knowledge related to the transmission modes of sars and preventive measures as well as support through a health education programme. ( ) to examine the effectiveness of the programme in terms of the participants' anxiety, knowledge about the main transmission routes of sars and measures for preventing sars. the study used a pretest/posttest design. potential subjects were recruited from registered members of a government subsidized social service center in the southern district of hong kong which provides various services to older adults such as home visits, social activities and meals-on-wheels service. the eligibility criteria were subjects who: ( ) aged or above; ( ) were able to speak cantonese; ( ) had no hearing impairment, and ( ) were reachable by telephone. initially, registered members of the social service center were contacted by telephone to determine their eligibility; a total of older adults were successfully contacted at baseline for health assessment and health education (i.e., response rate ¼ . %). however, only completed the post intervention questionnaire (i.e., follow-up rate ¼ %). the attrition in the follow-up was mainly due to refusal and non-response telephone calls ( fig. ). a survey instrument developed by leung et al. ( ) was modified and adapted for the use in this study. the original survey instrument comprised questions and is divided into seven parts: ( ) self-perceived general health status and level of anxiety; ( ) use of health services; ( ) possibility of contacting diagnosed sars cases; ( ) belief of contracting sars; ( ) knowledge of transmission of sars; ( ) measures taken to prevent transmission of sars; and ( ) socio-demographics. other details of the instrument have been described in so et al. ( ) and leung et al. ( ) . in this paper, the level of anxiety, knowledge level regarding sars transmission modes, and practice of preventive measures will be presented. twenty-six nursing students from the university of hong kong received a training programme conducted by faculty with expertise in gerontology, health education, and counseling. the training program aims to improve the students' knowledge and skills and it include: ( ) the purpose of the research including the research questions; ( ) how to conduct a telephone survey (e.g., communication techniques, how to obtain informed consent, consistent use of the study procedure, and data recording); ( ) how to communicate with the elders and to handle questions; ( ) assessment of their learning and ability through observation during role play and practice; and ( ) elucidate and reinforce compliance with study protocols. the institutional review board approved this study. all the potential subjects were approached via telephone during the period between and may to determine their eligibility. after gaining their verbal consent, interviewers collected the baseline data regarding the level of anxiety, knowledge and preventive measures taken to prevent transmission of sars. based on the results of the baseline data, the interviewer provided health education to the participants and clarified their misconceptions. a follow-up phone call was made week after the collection of the baseline data and interviewers used the same questionnaire for evaluation. the level of anxiety, knowledge and practice of preventive measures regarding sars were the main article in press outcome variables. descriptive statistics were used to assess all variables. paired-sample t-test was used to assess the level of anxiety before and after the intervention. the mcnemar test was used to examine the change of the level of knowledge about the transmission routes of sars prior to and after the intervention. sign test was used to investigate the change of practice of preventive measures before and after the intervention. an alpha of . or less was considered significant. information about the demographics of the participants is presented in table . the majority of the participants were female ( . %). more than half of the participants ( . %) did not live with the family. the majority did not have any formal education ( . %) or received low educational level ( . %). about . % were retired and did not have a monthly income. the levels of anxiety before and after the intervention are presented in table . only . % perceived a medium level of anxiety or above. while their anxiety level was generally low before the intervention, it was significantly lower following the intervention (t ¼ . , df ¼ , po . ). changes of the participants' knowledge of the three main transmission routes (droplets, direct physical contact, and urine/feces) before and after the intervention are presented in table . a significant difference was found in their knowledge of droplet (po . ) and urine/feaces (po . ) transmission. although no statistically significant change was found in the transmission route of direct physical contact (p . ), more participants answered correctly following the intervention. results of taking preventive measures before and after the intervention are presented in table soup (po . ), wearing mask in public (po . ), and avoiding the use of serving towels (po . ). older adults showed less frequent practice in some measures while more practice in others after the intervention. overall, the participants experienced low levels of anxiety at the time of baseline data collection. this may be due to geographic location among the participants who lived in an area with the least severe outbreak of sars. although their level of anxiety was low at both measurement periods, the mean total scores of anxiety were significantly lower after the intervention. more participants reported a low level of anxiety following the telephone intervention. these findings support those of car and sheikh ( ) , who reported that the provision of care through telephone is an effective means to provide psychosocial support to clients at home. significant changes of the knowledge of the two main transmission routes of sars (i.e., droplet and urine/ feaces) were noted after the intervention. although no statistical significant changes were found in the knowledge of direct physical contact transmissions before and after intervention (p . ), more participants' misconceptions were corrected after intervention. while the telephone could be an effective means of delivering health education to this vulnerable group, older adults usually take a longer time to acquire new knowledge and information (eliopoulos, ) , and continuing health education or further follow up calls may be necessary to monitor their knowledge regarding transmission of sars. our results showed that older adults had less frequent practice on some preventive measures at follow up. (spielberger, ) . mcnemar test was informed and no significant changes were found in all levels of anxiety. ÃÃà po . ; ns ¼ not significant; na ¼ not applicable. however, the mean difference between the preventive measures before and after the intervention was less than one, and therefore, the results could not reflect the actual behavioral outcomes. in fact, several factors may have affected the less frequent practice of the precau-tionary measures in the older adults. at the time of follow up, the situation of the sars epidemic had much improved, and the practice of preventive measures such as wearing masks may not be considered necessary by the older adults. however, personal hygiene practices such as washing hands after sneezing/coughing and contact with possible contaminated materials, had shown a slight increase in frequency of practice and it may imply that these practices could have been internalized as a routine practice and sustained after the intervention. other preventive measures as advised by the department of health, such as using serving spoons/chopsticks at mealtime and avoid using serving towels may not be relevant in this group because they lived alone. changing health behavior is a complex issue and individual as well as social contextual factors need to be taken into consideration. a single telephone call may not be sufficient to influence practice, but nevertheless it served as a means of support for the elderly during such epidemic. additional research is needed to clarify the lack of compliance to these measures, and how to influence the change of such behavior. although who removed hong kong from the sars list in june , the possibility of another outbreak of sars or other infectious diseases still exists. recently, the hong kong government emphasizes the importance of preparedness for an influenza pandemic table knowledge of main transmission routes of sars before and after intervention (n ¼ ) after intervention (n) p-value note: *** po . ; ** po . ; ns ¼ not significant. (hong kong health, welfare and food bureau, n.d.) and healthcare professionals play a vital role to deliver health promotion and education to the public. it is, therefore, important that healthcare professionals understand how to deliver key health-related information to the public effectively, particularly to vulnerable groups such as older adults with low socio-economic status (ses). in contrast to the general population, older adults in hong kong are comparatively socially isolated and have low literacy rates. alternative methods of disseminating essential information to older adults are important to enable them to acquire updated information and take appropriate preventive measures to maintain health. e-health is an effective method for health education and promotion and many older adults are more likely to have access to information technologies such as telephone and television. results of the study supported that telephone health education was effective in relieving anxiety and improving knowledge of the main transmission routes of sars in older adults, but not fostering practice of preventing sars. therefore, the strategy that this study used could be helpful for the future development of health education and promotion for older adults. a combined measure, such as television health education and telephone follow up calls may be desirable to improve health behaviour practices, especially when dealing with possibly pandemics such as avian and other influenzas. first, the older adults in this study were recruited from a district that was later reported to have the lowest infection and mortality rate of sars among the districts in hong kong. therefore, generalization of the results to all older adults in hong kong is questionable. furthermore, the study results indicated a low level of anxiety in the older adults, which could have resulted from living in a relatively ''safe'' district. second, the small sample size and a relatively short time period between the intervention and the follow-up may have resulted in the insignificant differences in the practice of preventive measures after the intervention. third, the infection rate of sars was gradually decreasing during the study period. the hong kong daily infection rate of sars (leung et al., ) was about cases per day during baseline data collection (may - , ) , and it further declined to about case per day during the -week follow-up. this could have affected the perceived importance of practicing the preventive measures since the overall risk seemed to have reduced as the epidemic was waning. further follow-up could be useful in identifying sustainable changes of relevant behaviors and practices. fourth, although providing telephone intervention was the safest means to communicate with the older adults during the sars epidemic, there were several drawbacks. for example, there is only limited amount of information that one can provide in a single telephone call. thus, the interviewers have to balance the time spent on each call and to ensure the provision of adequate information for each respondent. it is not advisable to overload the older adults with too much information, as they may not be able to capture and remember all the contents in one single telephone call. finally, the older adults might be exposed to other health education and preventive measures on sars via television and other media during the outbreak. therefore, it is difficult to attribute the positive changes solely to the interventions. this is the first systematic study to assess the effectiveness of telephone health education in improving older adults' knowledge and practice of preventive measures during the sars epidemic. our initial findings are encouraging in demonstrating the effectiveness of a telephone health education programme in relieving anxiety and improving knowledge of the main transmission routes of sars in older adults. however, an effective intervention to change the embedded health behaviors remains to be established and tested. the use of technologies such as telephone appears to be an effective means to educate and provide social support to the vulnerable older adults during outbreaks of sars and other possibly pandemic crises. future research should explore the effectiveness of health promotion programmes using multiple information technologies that are accessible to, and appropriate for, older adults in changing their health behavior practice. use of cholesterol-lowering therapy by elderly adults after myocardial infarction urinary incontinence knowledge among community-dwelling people years of age and older a pilot study of health education via a nurse-run telephone self-management programme for elderly people with osteoarthritis telephone consultations gerontological nursing effects of a telephone counseling intervention on psychosocial adjustment in women following a cardiac event implementation of efficacy enhancement nursing interventions with cardiac elders population census: hong kong resident population aged and over by quinqennial age group and educational attainment (highest level attended) hong kong's preparedness for influenza pandemic-prevention and protection sars in hong kong: from experience to action. retrieved october boosting uptake of influenza immunization: a randomized controlled trial of telephone appointing in general practice message from the president. the hong kong geriatrics society newsletter. the hong kong geriatrics society the epidemiology of severe acute respiratory syndrome in the hong kong epidemic: an analysis of all patients the impact of community psychological responses on outbreak control for severe acute respiratory syndrome in hong kong the meanings of age: selected papers of bernice l the knowledge level and precautionary measures taken by older adults during the sars outbreak in hong kong manual for the state-trait anxiety inventory (form y): self-evaluation questionnaire. consulting effectiveness of telephone counseling for mammography: results from five randomized trials rofecoxib improves quality of life in patients with hip or knee osteoarthritis world health organization (n.d.). e-health evidence of real-world effectiveness of a telephone quitline for smokers we thank the aberdeen kai fong welfare association social service centre for their cooperation, the bachelor of nursing students for conducting the telephone interviews, and professor judith parker for reviewing the manuscript. lastly, we are grateful to the sars research fund, the university of hong kong, for providing funding for this study. key: cord- -pxfwe t authors: leung, gabriel m.; chung, pui-hong; tsang, thomas; lim, wilina; chan, steve k.k.; chau, patsy; donnelly, christl a.; ghani, azra c.; fraser, christophe; riley, steven; ferguson, neil m.; anderson, roy m.; law, yuk-lung; mok, tina; ng, tonny; fu, alex; leung, pak-yin; peiris, j.s. malik; lam, tai-hing; hedley, anthony j. title: sars-cov antibody prevalence in all hong kong patient contacts date: - - journal: emerg infect dis doi: . /eid . sha: doc_id: cord_uid: pxfwe t a total of , asymptomatic close contacts of patients with severe acute respiratory (sars) from the epidemic in hong kong were serologically tested, and ( . %) were positive for sars coronavirus immunoglobulin g antibody. sars rarely manifests as a subclinical infection, and at present, wild animal species are the only important natural reservoirs of the virus. s ince severe acute respiratory syndrome (sars) and the coronavirus (sars-cov) that causes it have emerged and spread, considerable progress has been made in understanding the biology, pathogenesis, and epidemiologic features of both the virus and the disease. epidemiologic studies of hospitalized patients suggest that the overall transmissibility of sars (as indicated by the basic reproductive number r = . , % confidence interval [ci] . - . ) ( ) is relatively low compared to other pathogens. however, such studies could not take into account possible episodes of mild or moderate illness that did not require inpatient medical care and could not address whether asymptomatic community spread played a role in the epidemic. if this type of spread occurred, sufficient herd immunity against sars-cov to protect against another large-scale outbreak might have been developed in the population. the full spectrum of disease associated with sars-cov infection should be examined to define more precisely what constitutes a case requiring quarantine and isolation to minimize potential human-tohuman spread. understanding these issues requires the systematic study of the seroprevalence of sars-cov antibody in a large sample stratified by age and other baseline characteristics, especially since children were disproportionately less affected by sars, both in terms of reduced incidence and severity of infection. serologic surveys can be based on a random sample from the total population with appropriate stratification, on serum collected for other reasons (e.g., blood donors, all hospital admissions), or on surveys of persons who resided in sites of superspreading events or who have had close contact with a confirmed sars patient. we report a serologic survey for immunoglobulin (ig) g against sars-cov in a representative sample of close contacts of all sars patients in hong kong (> % had laboratory confirmation of sars by either paired serology or repeat reverse transcription-polymerase chain reaction (rt-pcr) according to world health organization [who] criteria [ ] ). during the epidemic, close contacts were prospectively identified by the hong kong special administrative region government department of health through standardized telephone interviews with all , confirmed sars patients within week of hospital admission (february -june , ). a close contact was defined as a person who had cared for, lived with (in the same household), or came into direct contact with body fluids of the sars patients within days before hospital admission. a total of , close contacts were recorded; were diagnosed as having sars. of the remaining , contacts, , ( %) had a telephone number available, as reported by the primary patient. we successfully contacted , ( %) from october to november , , and , ( % of those eligible) consented to a telephone interview after the purpose of the study was explained to them by trained public health nurses. the interview consisted of questions that assessed the relationship between the patients and contacts; the timing, intensity and frequency of contact; precautionary measures adopted during contact with the patient; known contact with other sars patients; clinical symptoms of febrile, respiratory, gastrointestinal, or constitutional illness since february ; medical and travel history; and sociodemographic details. participants were then invited to provide blood samples for serologic testing. shopping coupons (worth u.s. $ . ) were given to participants after blood was collected as compensation for time and travel costs. samples were screened by the government virus unit of the department of health by using viral lysate enzymelinked immunosorbent assay (elisa) (gbi biotech, beijing). positive results were confirmed with immunofluorescence assay (ifa) and neutralization tests. for the ifa, microscopic slides coated with sars-cov-infected frhk cells were incubated with serum samples at serial twofold dilutions starting from : . a positive test is indicated by cytoplasmic fluorescence under uv microscopy. by using ifa as the standard, the elisa detects antibody with ifa titer of > (i.e., sensitivity of %) and has a specificity of %. neutralization test was performed by standard virologic method with vero e cells and sars-cov isolate . a titer of > was considered positive. the reported sensitivity of % was for convalescentphase serum samples taken a few weeks after the onset of infection in sars patients, which should apply to our study. during the early phase of infection, igm predominates; the elisa kit we used detects igg only. therefore, the sensitivity is %- % (depending on the number of days after illness onset when the serum samples were taken). however, this sensitivity should not have affected our findings, which were based on tests carried out at least months after the last reported case of sars in hong kong. the study received ethics approval from the department of health ethics committee, which complies with the declaration of helsinki. of the , samples analyzed, ( . %, exact % ci . %- . %) had a positive titer ( : to : on ifa compared to at least : in most recovered sars cases) for sars-cov igg antibody. neither participant with a positive sample reported a chronic medical condition or being sick with febrile or respiratory illness from february to august. both seropositive participants arose from two superspreading events in hong kong, i.e., prince of wales hospital nosocomial outbreak and amoy gardens environmental point source community outbreak ( , ). the contact of the prince of wales hospital seropositive participant reported one other close contact, who was interviewed but declined to be tested. the other seropositive index patient living in amoy gardens was separately identified by three intrafamilial index patients, all of whom lived in the same household and reported only each other as close contacts. the participants who consented to testing were broadly similar to those who declined, except that the first group had relatively fewer children and fewer of the first group were men (table) . however, those who declined testing were more likely to report more frequent contact and closer relationships with sars patients, more febrile or respiratory illness episodes since february, and a travel history to sars-affected regions, which may have biased our seroprevalence estimate upwards. the extent of seroconversion in close contacts of confirmed patients should provide the upper limit of sars-cov antibody seroprevalence in the general population, given the relatively intense exposure history of these persons to sars patients. our finding of the near absence of transmission resulting in asymptomatic infection in this representative high-risk group of close contacts indicates that the prevailing sars-cov strains in hong kong almost always led to clinically apparent disease. whereas some sars patients, especially healthcare workers, might have been initially admitted to reduce transmission to family members, virtually all sars patients (perhaps with very few exceptions in children [ ] ) had severe disease requiring inpatient treatment; thus, we can infer that infection with sars-cov inevitably caused severe disease requiring hospitalization. although our results suggest that sars-cov was a new virus in humans without a close precursor or an antigenically related virus that would have induced at least a small degree of cross-reactivity on serologic testing, a recent study on a select group of healthy hong kong adults, whose serum had been previously stored as part of a hepatitis b serosurvey in , indicated that . % of the sample had acquired a sars-cov-related virus infection at least years before the sars outbreak ( ) . the investigators speculated that the virus that affected these healthy, seropositive persons was antigenically closer to the recently isolated animal sars-cov-like virus ( ) than human sars-cov, but interspecies transmission from animals to humans was probably inefficient, as the virus might not have adapted in the new host. this hypothesis would explain why only a few persons became infected and why they were likely to have been asymptomatic. this hypothesis would be compatible with the presumed asymptomatic infection observed in guangdong animal traders, especially in those who handled masked palm civets, who had a seropositivity rate of . % (exact % ci . %- . %) in the absence of prior overt clinical disease ( ) . the limitations of the study include incomplete contact tracing, especially in the earlier parts of the epidemic, and potential recall bias from underreporting of contacts by some patients who were too sick to answer questions. another possible shortcoming is the lack of a survey of close contacts who did not report a telephone number, although there is no reason to suspect they had a systematically different serologic profile. in fact, these were mostly nonhousehold contacts who would have had less intense exposure to sars patients. in addition, because peak infectivity, as indicated by viral load, usually occurred during week of illness ( ), when most of the patients would have been isolated in hospital (the mean onset-to-admission interval decreased from a maximum of . days in late february to . day by mid-may) ( ) , transmission to close contacts in the later stages of the epidemic was less likely. finally, contacts who refused to participate ( ) or refused to have serologic testing ( ) might have done so because they were concerned about having had sars (possibly because of having had sars-like symptoms) and did not want to be identified and stigmatized as having been infected with sars-cov. surveys in other countries with large-scale outbreaks such as canada, china, singapore, and taiwan should be undertaken to confirm our findings. includes washing hands before touching mouth, eyes, and nose; washing hands with soap; wearing face mask; using serving utensils during meals; adopting precautionary measures when touching possibly contaminated objects, washing hands after touching possibly contaminated objects; adopting home preventive measures (such as maintaining good ventilation and using bleach to clean surfaces and home appliances) against sars; and adopting workplace preventive measures (such as maintaining good ventilation, using bleach to clean surfaces and office furniture, and not allowing staff who are sick to come to work) against sars. transmission dynamics of the etiological agent of severe acute respiratory syndrome (sars) in hong kong: the impact of public health interventions use of laboratory methods for sars diagnosis isolation and characterization of viruses related to the sars coronavirus from animals in southern china clinical presentations and outcome of severe acute respiratory syndrome in children sars-related virus predating sars outbreak, hong kong prevalence of igg antibody to sars-associated coronavirus in animal traders-guangdong province clinical progression and viral load in a community outbreak of coronavirus-associated sars pneumonia: a prospective study epidemiological determinants of spread of causal agent of severe acute respiratory syndrome in hong kong we thank colleagues in the disease prevention and control division, regional offices, elderly health service and public health nursing division of the department of health for assistance in recruiting participants, collecting survey data and blood samples, and collating and processing multiple data sources used key: cord- -yetjd g authors: deng, ying; chan, edwin h.w.; poon, s. w. title: challenge-driven design for public housing: the case of hong kong date: - - journal: frontiers of architectural research doi: . /j.foar. . . sha: doc_id: cord_uid: yetjd g abstract public housing (ph) has existed in hong kong for six decades. previous and current challenges that have been encountered over time function as a collective driver for design progression. however, such challenges have remained under research to be able to draw useful lessons from them. to understand how this established motif can suit the sustainability-conscious era, this study uses hong kong as a representative case for sub-tropical compact cities by critiquing its ph design against multiple constraints. the objective of this study is to trace the historical relationships between challenges and design progress as well as to assess current and future implications of sustainability trends on ph design. by synthesizing data from literature, policy documents, and empirical evidence, this research develops an evolution map for ph design in hong kong that is driven by seven major challenges. based on this map, a conceptual framework for intersecting considerations that envisages five main future prospects toward future ph design is also established. ph became a major theme in residential architecture after the second world war (broto et al., ) as a response to the sharp decline in the number of available houses and the drastic increase in population across war-torn cities. the term for ph and its eligibility criteria may vary across regions, but the objective of providing affordable dwelling to those in need remains the same. even when urban backdrops are markedly different nowadays, ph still represents a considerable portion of the overall housing provision in some asian economies, i.e., . % in hong kong (census and statistics department (csd) , a) and over % in singapore (housing and development board (hdb), ). mainland china comprises % of the global population, but affordable housing in this area only makes up approximately % of its total housing portfolio (mok, ) . this situation explains the ambitious target of mainland china, i.e., an output of million units by (national development and reform commission (ndrc), ) . after decades of development, how have ph designs evolved against multiple challenges and kept abreast with the present era of sustainability, particularly in the aforementioned asian economies that still rely considerably on ph to address housing inequity? according to its dictionary definition, a challenge is a demanding but stimulating situation, task, or problem that requires considerable determination, wisdom, and strength to satisfy (cambridge advanced learner's dictionary and thesaurus, ; collins english dictionary, ) . although the concept of sustainability traverses across geographical boundaries, challenges remain context-dependent and can significantly influence the formulation of policy priorities and vernacular identities. nevertheless, challenges that are encountered over time under a particular context are seldom employed as an integrative driver in design progression. sustainable development has been commonly noted as underlining the capability of satisfying both short-and longterm requirements of different generations in symbiosis. however, only a few studies have mentioned that an overarching concern should be expressed toward the needs of individuals at the bottom of the economic pyramid, given that poverty and inequity significantly increase the chance of environmental and other types of crisis (united nations (un), ) . considering that environmental degradation, population growth, and poverty are inextricably bound, and each issue is impossible to address independently (un, ) , ph provides a good opportunity to manage these issues holistically. however, the unique contribution of ph to realizing the vision of multi-spherical sustainability is frequently understated. under the triple-pillar principle (un, ) , sustainable ph implies adopting intergenerational social equality to approach economical accommodation within ecological carrying capacities. following this logic, ph design should adapt to a sustainability challenge to balance budget consciousness, environmental enhancement, and social inclusiveness. to fill in this gap, this study is based on hong kong being a regional exemplar during its years of ph design progress against a persistent mismatch between the high demand for housing and the intermittent shortage in land supply, among other challenges. situated in the sub-tropical pearl river delta region of china, hong kong stands as one of the densest metropolises in the world, with a mid- population density of persons per km (csd, a). as illustrated in fig. , the city comprises hong kong island (the island), the kowloon peninsula (kowloon), and the new territories. the three major regions collectively occupy a land area of km . with only % of the areas being naturally developable (yeung and wong, ) , most of the remaining developed lands are created through reclamation. by mid- , . % of the territorial population of . million (csd, b) relies on ph in two major forms- . % in public rental housing (prh) and . % in subsidized sale flats (housing authority (ha), a). as a major ph provider, the hong kong ha has been statutorily committed to develop, retrofit, and manage an increasing stock of ph estates since . by march , the prh estates of ha are accommodating over million people (long term housing strategy steering committee (lthssc), ). to address the re-emergence of ph supply deficiency, the government of the hong kong special administrative region plans to provide approximately , prh units within a -year time frame starting in . the target annual prh supply accounts for nearly % of the total local housing supply (transport and housing bureau (thb), ). addressing the existing undersupply problem represents a key part of the contemporary history of hong kong. moreover, this process can offer useful insights to the east asian region by sharing the experience with areas that have similar compact urban settings as hong kong and with mainland china. the latter is an ambitious ph player with a pressing need to flatten its learning curve in this regard. this study aims to synopsize the history and reality of ph design in hong kong, as well as to contribute a conceptual framework by outlining major considerations toward sustainable ph design, in general. the history and reality referred to in this paper are divided by the year . the major reason for such division is the outbreak of the severe acute respiratory syndrome (sars) epidemic, which heightened awareness of ph design professionals and the society as a whole on the crucial relationships between occupant health and environmental degradation. such relationships were previously considered insignificant in vertically compact high-rise living quarters, including ph estates in hong kong. the three objectives of this study are as follows: to profile historical challenges and assess their influence on design progression, to understand the local implications of global trends on urban regeneration and building sustainability for local ph design, and to outline emerging and future prospects for satisfying sustainability challenges in ph design. desk and evidence-based studies were conducted to complement each other. factual data were obtained from policy documents, official reports and circulars, and academic publications on local ph development. empirical evidence was collected through housing workshops and conferences. in addition, field trips were made in regions where ph estates are concentrated. the rest of this paper is organized in as follows. section provides a brief review (from to ) of ph design progress in hong kong. section focuses on onwards by analyzing the latest policy initiatives and design innovations. section synopsizes the key findings into an evolution map of ph design in hong kong, which has been driven by seven major challenges since . by combining historical and current perspectives, the final section also concludes the article by providing a conceptual framework for considerations and five future prospects toward sustainable ph design. kong ( kong ( - the central theme of this section is to present how challenges that have been encountered over time influence ph designs in hong kong. as a crucial but missing component of extant ph literature, this section provides an overview of the seven major challenges encountered in ph. these challenges are presented in chronological order, but can be meaningfully grouped into three sub-categories based on their nature. one shortage -shortage in land provision (a leading longterm obstacle); three crises -squatter hazard, social unrest, and three shifts -shift in living pattern, demands, and demography. references are obtained from an enriched body of related literature. considering that some important events or milestones are described or debated on by virtually each author, albeit from different viewpoints, a list of all citations is provided to avoid unnecessary interruptions and repetitions for easy reading. the list includes: civil engineering and development department (cedd), , dickinson ( ) , gabriel ( ) , grange ( ) , ha ( - ha ( , a ha ( , b ha ( , c ha ( , b , housing authority and housing department (hahd), , hm ( , lthssc ( ), tong and wong ( ) , tsang ( ) , yan ( ) , yeung and wong ( ) , yip ( ) , yuen and yeh ( ) . as hong kong rose to become a major trading port during the mid- th century, its hilly geography became a major hindrance to its housing development and caused a congestion of tenement buildings along the harbor front. the large influxes of immigrants since the s exacerbated this problem and resulted in a sprawling area of timber squatter huts across the forested hills. such make-shift houses, which were constructed in the face of financial hardship, posed tremendous fire risk. on christmas night in , a huge fire destroyed a squatter camp and left , people homeless. this tragic event marked the beginning of ph development, which had not yet received political priority in any period in history. government provision became the only means to address such massive housing shortage. in , the fire victims were successfully settled in emergency housing units. on average, five adults shared an m unit. cooking was carried out at the corridor outside the unit, whereas tap water and sanitary facilities were centralized. the ground floor was partly reserved for basic community facilities and partly as an open space for natural ventilation. this hallmark of stilt houses, which is ubiquitous in sub-tropical southern china, remains as a feature of current ph estates. the resettlement department, which was the predecessor of the housing department, was established in to provide long-term housing options to other people who need them, apart from the fire victims. the first multistorey ph estate was completed in . considering the persistent squatter problem and the steady increase in income of local residents, the local government announced its ph policies in to accelerate the provision of resettlement estates. by , ph residents reached million. nevertheless, intermittent riots, which were partly triggered by the overcongestion problem in resettlement estates, erupted during the late s hence, formulating the first ten-year housing program ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) became reasonable. this program aimed to provide permanent and self-contained housing to . million people (out of the total population of . million during the time). however, implementing this ambitious program inevitably caused an immediate surge in land demand. on the side of hong kong island, the distance between the relatively flat waterfronts and the hilly regions is averaged at approximately . km, which physically limits infinite land acquisition. by the late s, most developable lands on the island and in kowloon had been virtually used up. the pressing need to decentralize the increasing population in these overcrowded urban regions ushered in a new town development model to practically implement the ten-year housing program by stages. this new development model, which mixed public and private housing developments, also offered an unprecedented opportunity for housing architects and urban planners to work together and create a new-generation ph prototype of the twin tower blocks. apart from an increase in flat size and an optimized layout, these high-rise estates were equipped with self-contained social and recreational amenities and were modeled largely on the british planning philosophy of self-contained community development. during the s, advances in construction technologies made building high-rise estates with up to stories possible. although these technological improvements significantly increased land-use efficiency and substantially reduced construction costs, the vertically compact housing style led to increasing concerns regarding its influence on internally and externally built environments. flat design optimization was carried out in various aspects, including the elimination of windowless rooms in each flat, the shortening of long and dark corridors, and allowing selfpartitioning by residents. as quality public spaces and amenities increasingly became a design focus in ph estates, landscape architects started to join the scene during the s and later became fully involved in designing open spaces and outdoor recreational facilities with housing architects. during its beginning, ph still largely functioned as an emergency resort. following the flat design norm, minimal space allocation was adopted to meet time pressures, overcome cost constraints, and achieve construction efficiency. the changing demographic and economic backdrops that began in the s resulted in the increasingly diversified demands of ph residents. consequently, spatial standardization was no longer a panacea for optimizing development potentials. by contrast, rigid design formulas were under intense debate because of the negative effects of their proliferation, namely, monotonous streetscapes that sharply contrast with the internationally acclaimed harbor-front skylines, cookie-cutter estates with low individual community identities, and low flexibility in furniture and fit-out arrangements for residents. some breakthroughs were gradually made during the s to provide a variety of flat mixes. the standard design approach was finally superseded in by the non-standard approach under the new site-specific strategy. the issue of the increasing aging population ( years and above) first emerged during the s the traditional housing design was aimed primarily for the needs of families and physically able individuals, which left single elders inadequately housed, particularly in the older estates. the enactment of the residential care homes ordinance in forced the closure of many private homes for elders. this event further intensified the demand to rehouse this longneglected yet rapidly expanding population group. with the implementation of the ten-year housing program ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) , the concept of "aging in place" was promoted to satisfy the life cycle requirements of residents. a universal design approach was introduced to new-generation ph estates, in which additional attention is given to interior fit-out details, multi-room layouts, barrier-free facilities, and convenient access to transportation, shopping, and other amenities. the outbreak of sars in raised public awareness on health and hygiene issues that stem from the compact, and sometimes, overcrowded living patterns that are ubiquitous in hong kong. during the peak of the epidemic, various public spaces were closed while communities were engaged in hygienic measures to reduce the incidence of respiratory viral infections. the outbreak also caused design professionals to rethink on how energy efficiency can be simultaneously satisfied with people-oriented issues in the advent of sustainable building designs. promoting sustainable communities became an underlying factor of subsequent housing policies to boost the local economy, and consequently, stimulate a supply-side pursuit for value-added housing design to regain public confidence. environmental sustainability has become a priority in designing new prh estates and retrofitting existing housing stock with continuing efforts to green ph estates and their surroundings. to specifically address the possible transmission of diseases through old drainage systems, which had been identified as the medium through which the sars virus had spread, ha collaborated with local academic institutions in developing innovative solutions to update drainage and ventilation systems, with good prospects in market applications. ph in hong kong was primarily a response to the aftermath of the squatter fire, which was a result of the widespread problems of squatter sprawl and housing congestion. lasting solutions that can eradicate serious housing inequity that undermines social cohesion were urgently required from the government side. the four major shifts in years of development are summarized as follows. low-cost housing: an emergency resort to offer temporary shelters to the fire victims and resettlement estates to low-income groups during the s and s quantity in housing: the ten-year housing program during the s offered permanent housing to citizens who need them and rehoused those living in resettlement blocks. quality housing: a paradigmatic shift during the s that resulted from the shifts in demography, demands, and living pattern. sustainable housing: adoption of a people-oriented strategy that began in the s to satisfy increasing public demand for sustainable communities. given that land acquisition became a major obstacle in sustaining the ten-year housing program implemented in , ph development in remote urban peripheral areas had been at the forefront in shaping the nine new towns in the new territories and in kowloon (fig. ) . table summarizes the evolution of local ph design since in key dimensions. excluding the three short-term crises, the rest of the obstacles identified in the previous section persist to the present. ph design at the local level has been further complicated by urban regeneration and building sustainability, which are the two key drivers of globally built environments. in many post-industrialized cities, most difficulties in urban regeneration originate from districts and old-generation new towns with aging housing stock, lagging infrastructure, serious environmental problems, and high concentration of low-income families. the local housing situations are further complicated by the following issues, among others. . situations are different from those of years ago when most local residents lived in hong kong island. a contributing factor to this shift is the relentless effort to develop nine new towns as an effective decentralizing strategy to accommodate the continuously growing population over the last four decades. among the nine new towns, seven are situated in the new territories and one is located in kowloon. by , the nine new towns collectively accommodate approximately . million people, and the number is expected to rise to . million by (cedd, ) . the significant concentration of ph population in the new territories and in kowloon indicates a high concentration of low-income population in these regions. moreover, among the , prh flats in , . % are years old and beyond the block age (ha, b). this figure, which presents a significant increase from the record of . % in , indicates aging and substandard housing stock amid accelerating environmental degradation. the increasing volume of unfit housing that requires retrofitting or replacement has a considerable influence on the urban regeneration process. under significant demographic shifts and severe social and environmental problems, "urban living space" was identified as one of the three key niches that are relevant to longterm local sustainability, whereas the strategies of redevelopment, rehabilitation, preservation, and revitalization were promoted to address degeneration of old urban quarters (center for sustainable design (cfsd), ). to satisfy long-term requirements for housing and infrastructure, several land supply options, including rezoning land, redevelopment, land resumption, and reuse of ex-quarry sites, have been adopted (cedd, ). among other efforts to alleviate the reemerging shortage in ph is a . ha development that can provide , prh flats (legco, ) . with the theme "homes in the park," this new project is part of the ha kai tak development to transform the former airport region into an international hub for tourism, sports, housing, and business (cedd, ). an unparalleled advantage of this mixed-use model lies in the shared network of transportation infrastructure and public amenities. however, initiating ph development at this scale is virtually impossible in the built-up inner city districts on the island and in kowloon, wherein numerous market-led land-use claims are competing. from the perspectives of economy and affordability, land price is sufficiently high to discourage any attempt to turn such prime locations into ph estates. to address this dual shortage, all suitable sites (regardless of size) have been acquired to maximize ph production (hahd, ) . a number of additional small developments on or adjacent to established ph neighborhoods are currently being established. these projects are the latest versions of sporadic pencil development, which has been favored for a long time by many local private developers and is typically characterized by a single high-rise development on a small infill site (adams and hastings, ) . on one hand, pencil development can boost ph production in every bit of renewable land in already intensified living quarters with spatial, geotechnical, environmental, and regulation constraints. on the other hand, the negative effects of weakening the existing vicinity by disregarding the need to upgrade or expand key infrastructure, public amenities, and transport networks in due course still need to be controled or curbed in such sporadic developments. this community-level issue is closely related to another global trend at the building level. in many established economies, a significant portion of the post-war housing stock that was mass-produced during the post-war era is now outdated (lawrence, ) . design insufficiency characterized by stereotyped minimalism, decontextualization, and environmental ignorance is regarded to have significantly contributed to such issue (brown et al., ; gu, ; williamson et al., ) . in principle, the organisation for economic co-operation and development ( ) recommends that sustainable buildings should be resource efficient, energy efficient, pollution preventive, environmentally harmonious, and methodically integrated. in practice, building performances are increasingly being monitored by innovative and comprehensive sustainability tools such as life cycle assessment and performance benchmarking systems in nearly countries and regions (kibert, ) . in hong kong, environmental sustainability in ph design has become a social imperative in the wake of the sars epidemic. although improving poor air quality has long been a focus of environmental improvement, health and social issues that are closely associated with environmental degradation remained low on the local policy agenda even after the sars epidemic (ng, ) . in , the local government began aiming for a voluntary carbon intensity reduction of %- % (from the level) by to position hong kong as a green exemplar of china (environmental protection department (epd), ). this program was followed by the launching of the first sustainable building assessment tool tailored for hong kong, i.e., the building environmental assessment method plus (beam plus). given the sub-tropical climate and the predominantly high-rise built environment in hong kong, beam plus considers a sustainable building to be safe, healthy, comfortable, functional, and efficient (green building council (gbc), ). as of , prh projects were assessed under beam plus and achieved platinum level (ha, d). despite the general lack of concern for economic-environmental and social-environmental sustainability before the implementation of beam plus, local ph design has been at the forefront of building eco-friendly, safe, healthy, sustainable, user-oriented, and cost-effective living communities (thb, ) . a site-specific and value-driven approach has been developed to optimize site potential, improve flat suitability, and enhance estate identity (legco, ). compiled from various sources (epd, ; fung, fung, , - hahd, ) , table presents nine major types of ph design initiatives and innovations established since to achieve improved design quality. for example, fully adopting a flexible housing production mix model requires strong inputs in both design and technical aspects, which leads to reforms in procuring consultancy services. since , an independent consultancy mechanism has been positioned as part of the integrated feedback and knowledge management system, upon which the modular flat design can be revised and optimized (ha, ) . in , the updated version of beam plus introduced an alternative route to assess building energy by encouraging the passive design strategy (gbc, ) to achieve comprehensive efficiency in space and energy use as well as in construction and operation costs. in line with the sustainable building design guidelines promulgated in (ba, ), model client briefs and contract specifications were introduced to ensure that all new ph projects would be beam plus-ready, with a minimum of gold rating for / onward (ha, d). aside from fostering industry-wide awareness in building sustainability, the granted extra gross floor area concession can be used to increase the number of dwelling units. this strategy is one of the latest approaches to address the undersupply of both land and housing. this section combines the findings from both historical and current perspectives and draws conclusions from these two dimensions. key initiatives and innovations site acquisition and land-use participation in strategic and regional studies to identify suitable residential land rezoning of non-residential sites "beam plus ready" -gross floor area concessions with beam plus registration urban planning and design strategic partnerships with academic institutions "enhanced two-envelope system" to put more weighing on the performance and design input "open design competition" to secure optimal site specific design for featured ph project "design and build" to pursue a more integrated design and production processes "direct appointment of consultants of different disciplines" to seek interdisciplinary expertise design optimization integrated feedback and knowledge management system independent consultancy mechanism to conduct resident surveys for new ph projects after a month move-in period ict-aided design building information modeling (bim) for generating highly accurate d data adoption of web-based geographic information system (gis) homesan on-line collaboration and management platform for stakeholders in accessing the whole project cycle information drawing management system as the first cross-divisional platform for drawing management seven major local challengesthree short-term crises, three long-term shifts, and one persistent obstacle. in form and function, ph in hong kong has evolved from simple low-rise living quarters with single-room flats and communal sanitary facilities into sophisticated high-rise buildings with self-contained multi-room flats. community facilities and amenities have also developed both in variety and sophistication. coupled with financial and climatic constraints, the shortage of land supply, as the leading challenge, has largely made high-rise living predominant since the s given that each block is regarded as a vertical community, the unique urban environment is endowed with amenities and landscape that exhibit vernacular and regional identities such as pillared arcades, podium/sky gardens, and social and commercial facilities connected by covered walkways. the incremental upgrade, which has been driven by multi-dimensional challenges over time, indicates that sustainability should not be considered as an add-on feature but as a process that should be attained stage by stage. some of these challenges are unique to the territory, several are common in the asia-pacific region, and others are globally relevant. moreover, this progress has dual implications for crises. first, the positive role of a crisis in revealing a fatal weakness that would be otherwise be left unattended during normal days is frequently ignored. despite its disastrous outcome, a crisis can catalyze a profound change, e.g., the squatter fire, the late s social unrest, and the sars epidemic provide strong evidence, among others. in addition, as exemplified in the case of hong kong, an emergency response, instead of being an end in itself, becomes a prologue to a comprehensive undertaking that places great importance to a city and its people. this phenomenon conveys another important message, i.e., although a crisis may short circuit some political procedures to catalyze a paradigmatic change, continuing to make progress for the sake of the users over time requires increased determination and additional systematic inputs regardless of how incremental the procedures have been. hong kong deserves credit in this regard. one practical implication for mainland china is the lesson that its ambitious social housing target cannot be achieved in an instant but through perseverance. given that economic hardship motivates fighting for value, challenges such as land availability, high density, and environmental degradation function as key drivers in seeking effective housing solutions that are easy to scale for mass production, high performance, and resource consciousness. although the preceding challenges have given significant impetus to achieve noticeable progress in ph, designs must respond to several emerging realities that are outlined as follows. although ph design has shifted away from traditional function optimizing and form making to place making and community building, a spectrum of urban issues with extensive social influences must be considered. for example, would the reemergence of the highly controversial pencil development be upgraded from merely being a quick fix to being applied as a means to renew old housing stock and satisfy the demands of the new ph population? by inheriting both positive and negative housing legacies from previous eras, pursuing a careful approach to initiating developments or redevelopments without overburdening existing neighborhoods and environments is imperative. consequently, design must extend the logic of buildings to community and city scales, which requires framing districtbased housing problems with community representatives and collaborating with organizations that work toward urban regeneration. the public sector that develops and manages substantial ph stock under budget constraints will always face the prioritysetting issues of where and how to best budget and finance housing adaptation, improvement, and maintenance. the ever-diversifying user demand resulting from demographic shifts will place an unforeseen pressure on housing stock, which is required to be adaptable to cater to the growing variety of households. employing forward thinking in designing enduring and adaptable housing is instrumental in reducing the recurrence rate of urban decay, which largely results from the fast-forward and low-cost driven housing design of the post-war era. with the primary objectives of mass production, minimal services, and low budget, ph has relied on a highly standardized design code over the past decades. however, future designs will be driven by the diverse needs of occupants for flats and estates with more variety, higher performance, and greater flexibility than old models. design processes will be subjected to comply with extensive and strict statutory obligations, as well as client specifications and supplementary guidelines. however, a highly standardized design process is a double-edge sword. codecompliant buildings should not be achieved at the expense of stilted creativity, and simultaneously, solutions should not be sought merely to score high in sustainability evaluation systems. pressing environmental degradation issues and devastating disasters have forced housing professionals to rethink the value of passive design strategies. worldwide, vernacular architecture has resulted from gaining experience in satisfying contextual challenges. such architecture creates the best possible built environment with locally available resources. history provides rich and diverse passive solutions to produce sun-oriented and insulated, as well as naturally ventilated and lighted housing, with smartly landscaped surroundings and well-preserved ecosystems. lowtech and high-tech solutions to sustainability should evolve in parallel. with the rapid progress in information communications and technology (ict), design has become interdisciplinary and participatory oriented. the interplay between adaptable sustainability and ict demands that the decision-making process should be synergized with physical, cultural, environmental, and aesthetic considerations with financial, technological, and network capacities. hence, a string of changes ensues. an example of an already noticeable change is that localized indices and methods are developed to assess the local feasibility of different options. consequently, housing professionals will be required to develop a strong familiarity with sustainability assessment tools. the fact that local regeneration projects have always been conflict-laden indicates a pressing need to increase constructive interaction with client and user groups, intensify inputs for design team management, and develop close collaboration with facility management crews. tapping the infinite potentials of ict in using design as a communication platform will provide considerable challenges and opportunities. to design contextually sustainable ph such as those discussed in preceding sections, fig. presents a conceptual framework for considering several intersecting portions of the three main aspects of sustainability. developing a sustainable ph design involves seeking economically and environmentally sound paths to address housing inequity as one of the biggest challenges in building an inclusive society. this logic applies to any given economy, regardless of whether ph accounts for a small or large portion of the overall housing provision. . . design challenges for public housing (ph) urban renewal in hong kong: transition from development corporation to renewal authority building design to foster a quality and sustainable built environment public housing: designs and inspirations. page one cambridge advanced learner's dictionary & thesaurus, . cambridge advanced learner's dictionary & thesaurus kai tak development project profile new towns and new major urban developments. hong kong: civil engineering and development department a first sustainable development strategy for hong kong kong: the facts. hong kong: information services department, hong kong special administrative region government report of the working party on government policies and practices: with regard to squatters, resettlement, and government low cost housing. the working party hong kong's climate change strategy and action agenda: consultation document. environmental protection department innovative noise mitigation designs and measures quality housing: partnering for change striving for continuous improvement innovative trends in the new era: hong kong housing authority's r&d strategy designing housing for the elderly in hong kong beam plus version . assessment method economic transformation and public housing reform in hong kong. contemporary china research project order of buildings and cities: a paradigm of open systems evolution for sustainable design model client brief for small households developments. hong kong housing authority hong kong housing authority sustainable housing: new horizons: / sustainability report. hong kong housing authority (i) measures to increase greening ratio of new public rental housing (prh) estates and (ii) provision of recreational facilities in existing estates actual public rental housing production block types public housing development sustainability report / . hong kong housing authority housing authority public rental housing portfolio. hong kong housing authority housing in figures. hong kong housing authority public housing: homes for the community: sixty years of public housing: cornerstone of hong kong's development. hong kong housing authority sustainability report / . hong kong housing authority hahd, . planning, design, and delivery of quality public housing in the new millennium. hong kong housing authority public housing in singapore memories of home - years of public housing in hong kong sustainable construction: green building design and delivery better understanding our cities: the role of urban indicators provisions for green, safe and healthy living in new public rental housing developments. hong kong: legislative council panel on housing public rental housing developments at kai tak sites a legislative council panel on housing lthssc, . long term housing strategy: building consensus, building homes consultation document. hong kong: long term housing strategy steering committee china could learn from singapore's public housing model the outline of the twelveth five-year plan for national & social development of the people's republic of china a critical review of hong kong's proposed climate change strategy and action agenda environmentally sustainable buildings: challenges and policies legislative council panel on housing: provisions for green, safe and healthy living in new public rental housing developments speech by the secretary for transport and housing at the legislative council special finance committee meeting (housing). retrieved the advantages of a high density meeting the needs of the elderly in public housing: the role of the hong kong housing authority. hong kong housing authority report of the world commission on environment and development: our common future report of the united nations conference on environment and development understanding sustainable architecture public housing in hong kong past, present and future: chartered institute of housing fifty years of public housing in hong kong: a golden jubilee review and appraisal the chinese university press for the hong kong housing authority greening initiatives in public rental housing estates. hong kong housing authority high-rise living in asian cities key: cord- -gt ey wz authors: wang, weiwen; ng, edward title: air ventilation assessment under unstable atmospheric stratification — a comparative study for hong kong date: - - journal: build environ doi: . /j.buildenv. . . sha: doc_id: cord_uid: gt ey wz in most current air ventilation assessment (ava) studies, a simple neutral assumption that does not consider thermal effects is adopted, particularly for numerical simulation practices. with statistics of daytime observations during summer in hong kong as an example, this study demonstrates that neutral atmospheric boundary conditions occur with a very low probability, which implies that current practices are indeed far away from reality. this study is devoted to addressing this knowledge gap by cross-comparisons of field measurements, wind tunnel tests, and large-eddy simulations (les) under neutral and unstable conditions. it is found that les-computed velocity ratios under unstable conditions are in line with field measurements, while results of simulations under neutral conditions are close to those of wind tunnel tests. enhanced vertical mixing due to surface heating produces improved ventilation performance in the unstable case. the neutral assumption tends to underestimate pedestrian-level velocity ratios compared to a diabatic condition; hence it is deemed conservative when it is adopted in ava practices. moreover, stronger wind direction variance under unstable conditions results in weaker correlation between velocity ratios and frontal area indices than neutral conditions, which implies that street orientations become less important in ventilation under unstable conditions. wind comfort and wind safety for pedestrians are important requirements for city design and urban planning [ ] . for subtropical high-density cities such as hong kong, in order to mitigate the negative effects of the urban heat island, good ventilation is required for healthy living and comfortable thermal sensations [ , ] . after hong kong was hit by the severe acute respiratory syndrome (sars), from which many people died in , the hong kong government started discussions among various government departments and consulted relevant professional institutes and stakeholders regarding the standards, scope, and mechanism for application of an air ventilation assessment (ava) system to improve the urban wind environment [ ] . afterwards, a set of planning guidelines was promoted based on a series of studies. the housing, planning and lands bureau and the environment, transport and works bureau jointly issued the air ventilation assessment technical guidelines (ava-tc - ) in . meanwhile, a new chapter on ventilation assessment was also incorporated into the hong kong planning standards and guidelines (hkpsg). these two documents, setting out the framework and requiring all major government departments to include ava as one of their planning and design considerations, were the first to address weak wind problems [ ] . unlike the guidelines of many countries for dealing with wind gust problems, the hong kong ava is specifically designed to deal with weak wind conditions in congested urban areas under a hot and humid subtropical climate [ ] . the world's first weak-wind urban ava system has been applied in hong kong in the city's design and planning practices for more than a decade. however, the current ava methodology is known to have limitations in that it cannot correctly predict urban air ventilation performance in some areas of hong kong where convective motion is prominent due to inhomogeneous surface heating in weak wind conditions [ ] . one possible cause is that the current ava methodology adopts the neutral assumption for the atmospheric boundary condition, which is justified only when mechanical turbulence has a greater influence on ventilation than buoyancy-induced turbulence under high background wind speed. however, the neutral assumption does not adequately represent the actual situation, as the daytime atmospheric boundary is likely to be unstably stratified, particularly under clear sky and low wind conditions [ ] . more importantly, the most crucial situations for urban ventilation are those in which only a low-speed background wind is present. the neutral assumption that supposes that buoyancy-induced turbulence has only a minor influence on ventilation is not true in such a condition. the atmospheric stability of the urban boundary layer is well known [ ] . meanwhile, many urban ventilation studies have used wind tunnel testing and computational fluid dynamics (cfd) models with a neutral assumption [ ] [ ] [ ] [ ] [ ] [ ] [ ] . but very few studies have addressed the effects of diabatic conditions on urban ventilation. a study of thermal effects on turbulence coherent structures found that when thermal effects are included by surface heating in large-eddy simulation (les), the spanwise flow is stronger within an idealized building array compared to the neutral case [ ] . another les study suggested that roof heating, in combination with building walls and ground heating, is important in the strength and location of the canyon vortex [ ] . both of these les studies used idealized urban geometries (cubical building arrays). using reynolds-averaged navier-stokes (rans) simulations of two simplified hong kong city models, yang and li pointed out that airflow in street canyons is dependent on thermal stratification when wind speed is small relative to the buoyancy force [ ] . however, how pedestrianlevel ventilation under thermal stratification differs from neutral conditions in a realistic urban complex is indistinct. the neutral assumption is widely adopted in ava practices, mainly because of its low computational cost and the ease with which it can be realized in numerical simulations and wind tunnel tests. when thermal conditions, specifically unstable stratification, are considered in ventilation, there will be additional challenges: first, a larger model domain is required to catch the larger turbulent structures in unstable simulations than in the neutral condition, while the grid size has to be kept small to sufficiently resolve the street-level air flows [ ] . second, special attention should be paid to the lateral boundary conditions to ensure that they will not artificially modify the wind environment within the assessment region. for instance, the radiative outflow condition in the non-cyclic boundary requires a positive outflow at all times [ , ] . therefore, while a weak background wind is provided for generating buoyancy-driven turbulence, extra model domain is needed on the leeward side of the city. this also requires extra computational cost. third, more uncertainties will be incorporated in the estimation of initial thermal conditions. heat fluxes are more difficult to monitor than winds. in such cases, validation of model results can be another obstacle. the objective of this study is to demonstrate the knowledge gap between current practices and reality by comparing wind tunnel test results, field measurements, and a pair of les experiments in hong kong, and to propose possible adaptations for future ava practices based on the comparative results and knowledge of atmospheric boundaries under various conditions. in ava studies, we are especially interested in pedestrian-level wind velocity. the wind velocity ratio (vr) is used as an indicator, which is calculated by vr = v p /v ∞ , where v p is the wind velocity at the pedestrian level ( m above the ground), and v ∞ is the wind velocity at the boundary layer not affected by ground roughness. apart from the meteorological data used in estimating the atmospheric stability class, this study includes some wind tunnel test results and field measurements from previous ava studies, and a pair of les experiments are undertaken for cross-comparison. utilizing observations from two urban weather stations in hong kong during - , we estimate the probability of stability classes according to pasquill's atmospheric stability classification scheme [ ] . hourly cloud cover data are taken from hong kong observatory headquarters, while wind speed and global solar radiation data are taken from king's park. the locations of these two weather stations are indicated in fig. . we consider daytime hours ( a.m.- p.m.) during all summer (june-august) days in - . as listed in table , atmospheric turbulences are categorized into six stability classes, namely a, b, c, d, e, and f, with class a being the most unstable, class f the most stable, and class d corresponding to neutral conditions. thresholds for wind speed and cloud cover are quantitatively specified, while the threshold for daytime insolation is given only qualitatively, in terms of "strong," "moderate," and "slight," which has to be transferred as specific values. based on hourly observations of global solar radiation from a.m. to p.m. on summer days, the th, th, and th percentiles are computed as . , . , and . mj m − , respectively. according to table , daytime stability is classified. for example, when wind speed is lower than , classifications a and b are divided by the th percentile of solar radiation; when wind speed is between and , classifications a and b are divided by the th percentile of solar radiation, classifications b and c are divided by the th percentile, and so forth. the probability of various classes of stability is calculated using all summer data during - . the estimated result suggests that neutral conditions occur with a very low probability of about only %; even the weak unstable class c occurs less than % of the time. during most of the daytime (about %), atmospheric stratification in urban hong kong can be classified as moderate and strongly unstable (classes b and a). however, the estimation may not be very accurate due to some deficiencies of this methodology. there are three limitations to the use of the pasquill stability classification scheme: first, the pasquill scheme is widely used mainly because it requires only routine meteorological data, but it was originally developed in the united kingdom at a location some miles from the coast, and should be restricted to the insolation values and climate conditions there. it has been found that various stability classification methods result in large discrepancies [ ] . second is the restriction of local observations to hong kong. hko is one of the two sites that have cloud cover observations (the other site is hong kong international airport). it is located in a small park that is surrounded by a high-density urban area in tsim sha tsui (fig. ) , with an altitude of m above mean sea level. kp is surrounded by a relatively larger green space on a small hill with an altitude of m on the kowloon peninsula. the uncertainties introduced to the classification of stability by such environmental conditions are difficult to control. finally, there is no information available as to how the parameters of strong, moderate, and slight should be chosen when the pasquill scheme is used locally in hong kong. due to the abovementioned limitations of stability classification using the pasquill scheme and ordinary meteorological observations, we use some samples of radiosonde observations to further demonstrate the probability of various types of atmospheric conditions in hong kong in summer. the radiosonde data are observed at king's park (fig. generally, sounding data are available only at : and : greenwich mean time (gmt), that is, : and : hong kong local time. in this study, sounding data recorded at : local time are used. we demonstrate the results from september (fig. ), when the street-level field measurements (introduced in section . ) are conducted. meanwhile, data from july , representing midsummer of the same year, are shown in fig. as well. fig. a boundary conditions should increase during summer afternoon hours compared to this time. in september, when the weather is cooler, the probability of unstable conditions decreases while the probability of stable and near-neutral conditions increases compared to july (fig. b ). in general, using both the pasquill stability classification scheme and the vertical gradient of θ e from radiosonde observations suggests that the probability of a neutrally stratified boundary layer in urban hong kong in summertime is not high; specifically, it is lower than the possibility of a thermally stratified boundary layer. the assumption of a neutral atmospheric boundary condition in air ventilation studies of hong kong is not representative. wind tunnel data are taken from an earlier ava study [ ] . the study was conducted by local researchers under the instruction of the hong kong planning department (hkpd). final reports can be downloaded from the hkpd web page [ ] . the wind tunnel tests were undertaken in accordance with international practice requirements and conducted at the clp power wind/wave tunnel facility (wwtf) of the hong kong university of science and technology [ ] . the clp power wwtf has a state-of-the-art subsonic boundary-layer wind tunnel. the overall size is . ground measurement data are adopted from the field measurements in "urban climatic map and standards for wind environment -feasibility study" [ ] . spot measurements were conducted using handheld equipment along preselected paths in tsim sha tsui. measurements were made along the paths at fixed points (fig. ) . the equipment used in the measurement included a -function sensor probe from testo [ ] for the measurement of air temperature and wind speed, and a testo data logger for instant processing of the measured data. the data logger was set with a sampling time of s and an averaging time of min. all the equipment was iso certified and was cross-calibrated in the laboratory before actual measurements were taken. field measurements carried out on september from : to : local time are utilized. it was a sunny and hot summer day. the air temperature observed at hko during the field measurements was - °c, and the relative humidity was %- %. the field measurements covered measurement points and reference point at the seafront in tsim sha tsui (fig. ) . twelve trained researchers were employed and grouped into teams to conduct the measurements. each group started the measurements at the first point (close to the seashore) of their corresponding path at the same time; that is, group started at g - , while group started at g - , etc. (fig. ) . during the measurements, measuring sensors were located m above the ground and logged the data. when the measurement time was up, the researchers recorded the data and moved on to the next point at the designated time. both temperature and wind speed were measured, but only wind data are used in this study. the values are listed in table . the rightmost column of table gives the time of measurement. mapping of the spatial distribution requires relatively stable weather conditions during the entire measurement period; that is, temporal variation of the weather conditions should be insignificant [ ] . this requirement has been fulfilled for the field measurements used in this study. however, as all test points cannot be measured at the same time, uncertainties that could affect the results of the comparison between the measurements and numerical simulations are unavoidable. moreover, the limited sampling time ( min) for each point could import another uncertainty, as the les represents a more stable situation with an hourly average. the realistic environment is difficult to fully consider in numerical modeling-for instance, the effects of greenery and traffic. we employ an les model to carry out cfd simulations in this study. les overcomes the deficiencies of the rans model by explicitly resolving large, energy-containing turbulent eddies and parameterizing only subgrid-scale (sgs) turbulence [ , ] . les provides not only mean flow fields but also instantaneous turbulences, which are especially important for human comfort at the pedestrian level in the urban canopy layer. the les model used in this study is the parallelized les model (palm), which was developed in , when it was one of the first parallelized les models for atmospheric research [ ] . the les model has six prognostic quantities by default: the velocity components u v w , , on a cartesian grid, the potential temperature θ, specific humidity q v or a passive scalar s, and the sgs turbulent kinetic energy e. the governing equations are based on the non-hydrostatic, filtered, incompressible navier-stokes equations with boussinesq approximation and are filtered implicitly using the volume-balance approach of schumann [ ] . the governing equations of palm are given in maronga et al. [ ] . the modified version [ , ] of the . -order deardorff scheme [ ] is used for turbulence closure. the temperton algorithm [ ] for the fast fourier transform is used to solve the poisson equation for the perturbation pressure. for the time integration, a third-order runge-kutta scheme [ ] is used. the advection scheme used is the secondorder scheme of piacsek and williams [ ] . alternatively, a fifth-order scheme developed by wicker and skamarock [ ] can be utilized. the monin-obukhov similarity theory (most) is applied between the surface and the first grid level. following the most, a constant flux layer is assumed as the boundary condition between the surface and the first grid level where scalars and horizontal velocities are defined [ ] . a prandtl layer is assumed at each surface. if non-cyclic horizontal boundary conditions are used, palm provides the possibility of generating time-dependent turbulent inflow by using a turbulence-recycling method, which follows the one described by lund et al. [ ] with modifications introduced by kataoka and mizuno [ ] . in front of the simulation domain, a recycling area is attached. the outflow boundary of this recycling area is the recycling plane, from where the turbulence signal ′ φ y z t ( , , ) is recycled: where x recycle is the distance from the inflow boundary to the recycling plane, that is added to the mean inflow profile after each time step. the recycling area length x recycle should be much larger than the integral length scale of the respective turbulent flow to avoid the same turbulence structures being recycled repeatedly. hence a precursor run, which can have a comparatively small domain horizontally for generating the initial turbulence field of the main run, is promoted [ ] . the computational domain is depicted in fig. . the urban area is taken from the black box in fig. , which encloses an area of km by km on the southeastern edge of the kowloon peninsula. in front of the city, a turbulence recycling area is added to the domain, where the turbulence-recycling method is applied to create a turbulent inflow for the simulation. the size of the recycling area is m by km, and it is m away from the city area. the m × km buffer zone between x recycle and the city helps prevent the blocking effects of the buildings from reaching the recycling area, while the km × km buffer zone on the leeward side of the city helps ensure a positive outflow. as introduced, the radiative outflow condition in this non-cyclic boundary always requires a positive outflow. the topography was rotated °( north is downward) due to the requirement of the turbulence-recycling method that inflow must come from the left. horizontal grid spacing is equidistantly m. grid-sensitive tests using palm . for urban ventilation simulations have been conducted in recent studies and suggest that a grid size of m is sufficient for such a task [ , ] . vertical grid spacing is m below m and is stretched with a stretch factor of . above. with vertical levels, the top level is at about m. in the les model, scalar variables are defined at the grid centers, while velocity components are shifted by half of the grid spacing. therefore, horizontal wind velocity output from the m and m levels is linearly interpolated (averaged) to obtain v p at m above the ground. the no-slip bottom boundary condition and the freeslip top boundary condition are applied to the horizontal velocity components. a cyclic (periodic) boundary condition setup in the spanwise direction is implemented. a low-velocity wind of . ms- is prescribed. as introduced, we focus on the crucial situation for urban ventilation in which only a lowspeed background wind is present. under such low wind conditions, the influence of buoyancy-induced turbulence becomes important, and ventilation will depend on the balance between thermal forcing and wind forcing. in addition, if high wind speed is used, more computational time will be needed because the time step has to be shorter. but a low background wind speed also requires a large buffer zone behind the city to ensure a positive outflow (fig. ) . the time step lengths are optimized in the les model. in the les experiments described below, the mean time step lengths are between . s (for the unstable cases) and . s (for the neutral case). a h precursor run, with a horizontal domain of m × m and the same height as the main run, is promoted for generating initial turbulent inflow profiles. the total simulation time for the main run is h. the first hour is excluded in the analysis of the results, as the turbulences need this time to spin-up. the simulated results of the second hour are averaged for analysis. simulations are performed with different atmospheric stratification. the first simulation features a neutral stratification in which the influence of temperature on the flow field is excluded; that is, the calculation of the temperature equation is switched off. in this case, the major output elements are velocity components. other simulations feature an unstable stratification realized by a prescribed homogeneous potential temperature of k below m and a capping inversion layer above with a potential temperature gradient of k per m, which is a general temperature setup for simulations of a convective boundary layer. more importantly, prescribed heat fluxes are generated from building rooftops and side walls. as in a realistic urban area with rather complex urban form, the thermal conditions and their balance with the velocity field are difficult to quantitatively decide by heat flux table for details. generation in the numerical simulation. therefore, we carry out a set of test runs, namely t , t , t , and t , with various prescribed rooftop and side wall heat flux settings, as listed in table . we deem that the approaching winds are always under neutral stratification due to general high wind speeds and very small surface roughness over open sea waters. therefore, no surface heat fluxes are prescribed in the turbulence recycling area and the buffer zones. the bulk richardson number (r b ) is estimated to examine the unstable stratified boundary layers of the simulations: where = − g m s . is the acceleration of gravity, z ct is the height of the canopy top, estimated at m in this study (refer to fig. ), θ is the potential temperature at the bottom (the lowest model level), and θ ct and u ct are the potential temperature and wind speed at the canopy top ( m), respectively. the parameters in table are averaged from the km × km city area. herein, r b for diabatic test runs is estimated, ranging from − . to − . in table . the more heat fluxes that are given in the les, the larger the absolute r b value that will be obtained. fig. demonstrates the potential temperature profiles averaged from y-z sections that cross the city (at x = m, m, and m in fig. ) from diabatic les experiments. the les model has been validated for simulating flows and turbulence characteristics at the street-canyon and neighbourhood scale [ ] and has been widely used in studies of urban street-canyon flows [ ] [ ] [ ] [ ] , including high-density urban areas in hong kong [ ] and macau [ ] . the code used in this study (palm version . ) has been validated by a cfd guideline [ ] for pedestrian-level ventilation under neutral atmospheric conditions in recent studies [ , ] . for simulation of the thermally stratified urban boundary layer, the model has been validated by uehara's wind tunnel data [ ] for thermally stratified street canyons [ ] . this study focuses on pedestrian-level ventilation. simulation outputs from the les model are cross-compared with wind tunnel tests (under neutral conditions) and field measurements (under unstable conditions), which will be presented in the following section. wind tunnel test data, field measurements, and les outputs are cross-compared to quantify their similarities and differences. we attempt to discover what causes deviations in pedestrian-level ventilation in different atmospheric conditions. in addition to wind speed, wind direction will be investigated as well. but first of all, we have to determine which diabatic simulation (t , t , t , or t ) best represents the typical actual boundary conditions. the atmospheric stability of the urban boundary during the field measurements is estimated by meteorological observations. it is found that the hourly-averaged wind speed and global solar radiation observed at king's park (fig. ) at p.m. on september are . ms - and . mj m − , respectively. according to pasquill's classification scheme (table ) and the thresholds introduced above (here we simply apply the summer thresholds to the field measurement days in september), it can be deduced that there were unstable (class b) atmospheric conditions at the time the field measurements were taken. there are very few data regarding r b in urban areas, and we are short of quantitative measurements for estimating r b in the urban boundary in hong kong. nakamura and oke measured the temperature and wind distribution in a real street canyon and provided an r b range from − . to − . on a clear midsummer afternoon [ ] . the estimated values of r b for the diabatic runs in the present study, ranging from − . to − . (table ) , are close to the field-measured values of nakamura and oke [ ] . the stratified conditions of the les experiments can reproduce those observed in realistic urban areas. meanwhile, taking the comparison of the observed r b in nakamura and oke [ ] into consideration, wind tunnel experiments with thermal stratification by uehara et al. [ ] suggest a set of tested values of − . , − . , and − . for a weakly to moderately unstable stratified urban boundary layer. evaluating our les results in table by this set of tested values in wind tunnel experiments of unstable stratification, t , with an r b of − . , is deemed to be the best at reproducing a typical unstable stratified urban boundary layer. it is noteworthy that the wind tunnel speed v ∞ of uehara et al. [ ] is . ms - as well, the same as the setting in our les experiments. therefore, t , with a mean kinematic heat flux of . km s- (about . w m - ) prescribed to all building rooftops, and a mean kinematic heat flux of . kms - prescribed to all building side walls, is chosen as the final diabatic simulation for the following comparative study. it is difficult to estimate v ∞ in calculating vr for field measurements. the reference point at the seafront (fig. ) is deemed unsuitable, as it measures near-surface ( m above the ground) wind speed in front of the city. we propose the wind observed at waglan island as v ∞ . waglan island is located approximately km southeast of hong kong island and has uninterrupted exposure to winds (fig. ) . with a very small surface roughness over open sea waters [ ] and a relatively high anemometer elevation ( m above mean sea level) [ ] , data collected at waglan island are considered to be representative of the boundary-layer wind approaching hong kong. hourly wind speed observed at waglan island at p.m. on september is . ms - . the wind speeds in table are divided by this value to gain the field-measured vr. wind tunnel tests described in section . are conducted under the neutral assumption. among wind tunnel test points and field measurement points, there are overlapping points (excluding the reference point at the seafront). the ids of these points in both the field measurements and wind tunnel tests are listed in table , together with their corresponding vr values. the mean values in table suggest that the wind tunnel experiments may have underestimated the mean vr compared to field measurements. les-computed vr under neutral and unstable atmospheric conditions in tsim sha tsui are shown in fig. . it is obvious that the overall ventilation inside the city in the unstable experiment is better (with larger vr) than that in the neutral experiment. the overlapping test points of the wind tunnel and field measurements are located on the vr map of les. corresponding values are listed in table to enable crosscomparison. the mean values given in table show that the les experiment under neutral conditions is more comparable to the wind tunnel tests, while the les experiment under unstable conditions is more comparable to the field measurements. this is further demonstrated in the scatter plots and linear regressions in fig. . fig. shows that the wind tunnel predicts a relatively lower vr compared to field measurements, with a regression coefficient of . in fig. a . also, given an r-squared of . , the regression between wind tunnel tests and field measurements is not very convincing. the [ ] . v bl is the boundary-layer velocity. building and environment ( ) [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] regression between the wind tunnel and les neutral is better, with a regression coefficient closer to ( . ) and a larger r-squared of . (fig. b) . the linear relation between field measurements and the diabatic les experiment is like that of fig. c , giving a regression coefficient of . and an r-squared of . (fig. c) . moreover, geometrical features of pedestrian-level vr obtained from these methods are shown in fig. . the best-ventilated areas are located around the main chatham road south (see fig. ) for all cases in fig. . in the narrow streets west of chatham road south, vr is around . for field measurements and the les unstable run, but decreases to about . in the les neutral run and even below . in some areas in the wind tunnel tests. according to our knowledge of boundary-layer meteorology, nearsurface velocity over boundary-layer velocity is larger in an unstable atmospheric boundary layer than in a neutral one (fig. ) . therefore, the wind tunnel tests predict a lower vr for the overlapping test points compared to the field measurements, which should be caused by the difference in atmospheric conditions; that is, neutral in the wind tunnel but unstable in the field measurements. wind profiles under different types of atmospheric boundary layers in fig. also explain why ventilation in the diabatic les experiment is overall better than that under neutral conditions. fig. depicts some les-simulated zonal wind (u-wind) profiles, both in front of the city and in the middle of the city. these profiles demonstrate that the diabatic les experiment produces greater near-surface velocity than the neutral case, especially inside the city where surface (building) heating is provided. the higher wind speed in the diabatic case is related to the additional convective motion caused by heating from the buildings, which increases vertical mixing throughout the boundary layer in and above the city and leads to higher pedestrian-level ventilation compared to the neutral case. the vertical velocity sections in fig. show that in front of the city, the vertical velocity fluxes are generated by the turbulence recycling method, without the surface heating difference, and the diabatic case (fig. b) is similar to the neutral case (fig. a) in the lower levels. the differences in the top levels are produced by temperature gradients in the capping inversion. in the middle of the city, much stronger vertical motion is found in and above the street canyons in the unstable case (fig. d ) than in the neutral case (fig. c) . the previous section illustrates that better ventilation under unstable conditions is caused by surface heating and enhanced vertical mixing. in this section, the differences between the les experiments under neutral and unstable conditions will be quantitatively compared. this is shown in fig. , which compares vrs taken from random test points in the city of the two les experiments. in this procedure, all street (unbuilt) grid points in each les experiment are stored in a one-dimensional array, and , test points (about % of the total unbuilt grid points) are randomly taken from each array. the random function calculates the interval between test points using a normal distribution with a mean of the array size divided by the number of test points ( , ) and a standard deviation of % of the mean. the test points are randomly spread throughout the entire assessment area. sensitivity tests were conducted regarding the number of test points, and no significant differences were found when the number of test points was larger than , , which means that , test points are sufficient to produce the graphs in fig. . both the probability and the boxplot are produced by these , data points. fig. a shows that the diabatic les experiment improves ventilation performance by increasing (decreasing) the probability of vr above (below) . compared to the neutral case. in each box of building and environment ( ) [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] fig. b, the central mark is the median, the edges of the box are the th and th percentiles, and the whiskers extend to the most extreme data points [ ] . it is obvious that all statistics except the minimum value in the diabatic les experiment are significantly larger than in the neutral case. the median of vr in the unstable case is . , twice that in the neutral case ( . ). the maximum vr in the unstable and neutral cases is . and . , respectively. additional convective motion caused by heating in the unstable experiment increases not only wind speed, but also fluctuations in wind direction. we select two points, one located in a narrow street parallel to the input wind direction (point as denoted in fig. ), the other located in a wide street perpendicular to the inflow wind direction (point as denoted in fig. ). the surrounding building shapes of these two points vary largely, but we focus only on the wind variation under the two atmospheric conditions, rather than the surrounding urban wind direction in the parallel street canyon is more homogeneous (fig. a ) compared to that in the perpendicular location (fig. b) , where intense rotations of wind occur in the lee of the buildings. but in both locations, we experience larger variance of wind direction in the unstable case than in the neutral case. additional convective motion and enlarged eddy size due to surface heating should be major contributors to this difference in wind direction variance between the neutral and unstable cases. stronger variation in wind direction under unstable conditions implies that street orientation may be less important in urban ventilation compared to neutral conditions. this is verified by fig. a . the frontal area index (λ f ), which is defined as the frontal area of buildings in a certain wind direction over a site area [ ] , is calculated from building data used in the simulations. this index has been widely used in urban wind environment investigations and is found to be an important morphological factor that influences urban ventilation [ , ] . we compute only the frontal area index, rather than frontal area density, as we have only one inflow wind direction. frontal area density is the accumulation of frontal area indices in all wind directions, weighted by the observed occurrences of different directions. frontal area indices are calculated from m × m averaging areas inside the km × km city domain. in order to obtain more data samples, the averaging areas overlap. this is also a way to guarantee that the results are not influenced by random positioning of the averaging areas. in this procedure, the first averaging area covers a m × m region in one corner, say, the left-bottom corner of the city domain. the next averaging area moves m ( model grids) forward in one (x or y) direction, and so forth. in this way, a total of data samples are obtained in the km city domain. the vrs are also averaged in such a way in both the neutral and unstable cases. fig. a demonstrates that pedestrian-level vr under neutral conditions gives a correlation of − . with the λ f , which is significantly larger than − . in the unstable case. hence, street orientation seems to be less important for urban ventilation under unstable conditions due to larger wind direction variance compared to neutral conditions. the limitation of this is that the relationship between ventilation and λ f is hard to justify given that only one wind angle is tested. fig. b further demonstrates a scatter plot and regression between vr and the ground coverage ratio (λ p ), which is defined as the ratio of ground area that is covered by the building to the site area. this parameter is computed using the same averaging areas and moving-window algorithm that were used in the calculation of λ f . more importantly, λ p is independent of wind direction. fig. suggests that the correlation between vr and λ p is higher than that between vr and λ f in both the neutral and unstable cases. the vr under neutral conditions gives a correlation of − . with λ p , which is still larger than − . in the unstable case (fig. b) . one possible cause is that stronger convective motion (fig. ) and greater wind direction variance (fig. ) in the unstable case reduce the effects of urban form and urban density on ventilation. nevertheless, these results are still restricted by the limited domain and the complexity of the realistic urban morphology tested in the simulations. future studies using parametric urban forms and urban densities while considering more input wind directions should be conducted to expand the preliminary result of this study. in general, the neutral assumption, which does not consider thermal stratification in air dynamics, is a simple but widely accepted assumption for urban wind studies. but the fact that neutral conditions occur with a relatively low probability in summertime, as shown in both the pasquill stability classification scheme and the vertical gradient θ e from radiosonde observations in section . , invokes the consideration of thermal stratification in studies of urban ventilation. in this case study, we cross-compare pedestrian-level vr taken from field measurements, wind tunnel tests, and a pair of les experiments in a high-density area of hong kong. the wind tunnel test under the neutral assumption is found to underestimate the ventilation as measured by pedestrian-level vr compared to the field measurements, which were taken during unstable atmospheric conditions (fig. a) . at the same time, the results of the les experiment under the neutral assumption are consistent with those of the wind tunnel tests (fig. b) , while the unstable les run captures the reality (field measurements) well (fig. c) . such findings theoretically agree with our knowledge that near-surface wind speed over boundary-layer velocity should be significantly larger in unstable stratification than in neutral stratification (fig. ) . the major cause is additional convective motion caused by surface heating, which increases vertical mixing throughout the boundary layer in and above the city. these thermodynamical features are well captured by the les experiments (figs. and ). the quantitative difference in the les results under neutral and unstable conditions are analyzed by vrs taken from random test points in the city (fig. ) . impacts of different types of atmospheric conditions on wind direction variance in simulations of ventilation are evaluated. an unstable boundary induces stronger wind direction variance compared to a neutral boundary in the urban areas (fig. ) . therefore, the effects of street orientation on urban ventilation may be less important in an unstable boundary layer than in a neutral boundary layer. this is demonstrated by the regressions of the frontal area index and pedestrianlevel vr under different types of atmospheric conditions (fig. ) . according to the findings in sections . - . , we can deduce that current ava practices under the neutral assumption are conservative if the actual atmospheric boundary is unstably stratified. but it is also noteworthy that unstable stratification generally occurs under weak wind conditions ( table ) . as the background wind (the boundary-layer velocity in fig. ) is weak, though the pedestrian-level vr under unstable conditions is significantly larger than that under neutral conditions, the actual wind environment, that is, the absolute wind speed at the pedestrian level, will not improve as much as the vr. we considered only neutral and unstable stratifications in this study and did not look at stable stratification. urban ventilation studies under stable atmospheric conditions are difficult due to a lack of in situ observations, and modeling (with a wind tunnel or cfd) of this type of thermal stratification is challenging. but the effects of a stably stratified boundary on urban ventilation should be the subject of a future study. according to fig. , stable boundary conditions may be the worst situation for urban ventilation, as they produce the smallest near-surface velocity over boundary-layer velocity compared to the other two types of conditions, and the background wind is generally not very strong (table ) . to conclude, wind tunnel tests under the neutral assumption underestimate the overall ventilation as measured by pedestrian-level vr compared to field measurements, which were conducted during an unstably stratified atmospheric boundary. vrs in the unstable les case are in line with field measurements, while those in the neutral case are close to the wind tunnel tests. overall ventilation under unstable conditions is found to be better than that under neutral conditions. current ava practices under the neutral assumption are conservative if the actual situation includes an unstably stratified boundary layer. enhanced convective motion due to surface heating in unstable conditions is the main reason the neutral assumption can be conservative. moreover, stronger wind direction variance under unstable conditions results in weaker correlation between vrs and frontal area indices than under neutral conditions. this implies that street orientation is less important in street-level ventilation under unstable conditions than in neutral conditions, due to the importance of surface heating effects in unstable conditions. cfd simulation for pedestrian wind comfort and wind safety in urban areas: general decision framework and case study for the eindhoven university campus urban heat islands in hong kong: statistical modeling and trend detection urban human thermal comfort in hot and humid hong kong, energy build policies and technical guidelines for urban planning of high-density citiesair ventilation assessment (ava) of hong kong urban climate challenges in the tropics: rethinking planning and design opportunities determining site wind availability for air ventilation assessment in hong kong's coastal and highly complex topographical conditions parametric studies of urban morphologies of high density cities and their air ventilation performance under neutral and unstable atmospheric conditions using advanced large-eddy simulations progress in observing and modelling the urban boundary layer building porosity for better urban ventilation in high-density citiesa computational parametric study natural ventilation assessment in typical open and semi-open urban environments under various wind directions pedestrian-level wind conditions around buildings: review of wind-tunnel and cfd techniques and their accuracy for wind comfort assessment impacts of cross-ventilation on the air quality in street canyons with different building arrangements pedestrian level wind environment assessment around group of high-rise cross-shaped buildings: effect of building shape, separation and orientation the impacts of building height variations and building packing densities on flow adjustment and city breathability in idealized urban models cfd simulation of flow in a long street canyon under a perpendicular wind direction: evaluation of three computational settings a large-eddy simulation study of thermal effects on turbulence coherent structures in and above a building array realistic solar heating in urban areas: air exchange and street-canyon ventilation thermal conditions and ventilation in an ideal city model of hong kong effects of unstable stratification on ventilation in hong kong a simple boundary condition for unbounded hyperbolic flows radiation conditions for the lateral boundaries of limitedarea numerical models the estimation of the dispersion of windborne material analysis of various schemes for the estimation of atmospheric stability classification working paper b: wind tunnel benchmarking studies, urban climatic map and standards for wind environment -feasibility study hkpd wwtf methodologies and results of field measurement, urban climatic map and standards for wind environment -feasibility study mapping the urban microclimatic spatial distribution in a sub-tropical high-density urban environment status of large eddy simulation: results of a workshop towards practical use of les in wind engineering palm -a large-eddy simulation model performing on massively parallel computers subgrid scale model for finite difference simulations of turbulent flows in plane channels and annuli the parallelized large-eddy simulation model (palm) version . for atmospheric and oceanic flows: model formulation, recent developments, and future perspectives spectral analysis of large-eddy simulations of the convective boundary layer large-eddy simulation of the stably stratified planetary boundary layer stratocumulus-capped mixed layers derived from a three-dimensional model, boundary-layer meteorol a generalized prime factor fft algorithm for any n = p q r low-storage runge-kutta schemes conservation properties of convection difference schemes time-splitting methods for elastic models using forward time schemes generation of turbulent inflow data for spatiallydeveloping boundary layer simulations numerical flow computation around aeroelastic d square cylinder using inflow turbulence first results of high resolution large-eddy simulations of the atmospheric boundary layer high resolution urban large-eddy simulation studies from street canyon to neighbourhood scale a new aerodynamic parameterization for real urban surfaces analysis of airflow over building arrays for assessment of urban wind environment large-eddy simulation of coherent flow structures within a cubical canopy large-eddy simulations of convective boundary layers over flat and urbanlike surfaces les case study on pedestrian level ventilation in two neighbourhoods in hong kong aij guidelines for practical applications of cfd to pedestrian wind environment around buildings large-eddy simulations of ventilation for thermal comfort -a parametric study of generic urban configurations with perpendicular approaching winds evaluation of satellite-derived building height extraction by cfd simulations: a case study of neighborhood-scale ventilation in hong kong wind tunnel experiments on how thermal stratification affects flow in and above urban street canyons a large-eddy simulation study of thermal effects on turbulent flow and dispersion in and above a street canyon wind, temperature and stability condition in an east-west oriented urban canyon determining the power-law wind-profile exponent under near-neutral stability conditions at sea quantifying urban heat island an introduction to boundary layer meteorology variations of boxplots urban morphology detection and computation for urban climate research improving the wind environment in high-density cities by understanding urban morphology and surface roughness: a study in hong kong quantitative ventilation assessments of idealized urban canopy layers with various urban layouts and the same building packing density key: cord- -h vnfcuq authors: lee, s. h.; lee, w. l. title: site verification and modeling of desiccant-based system as an alternative to conventional air-conditioning systems for wet markets date: - - journal: energy doi: . /j.energy. . . sha: doc_id: cord_uid: h vnfcuq abstract desiccant cooling system for active humidity control and to conserve energy has been in commercial applications for over two decades. however, its use in humid wet markets has never been examined. a gas-fired desiccant cooling system has been installed in a wet market in hong kong. in this study, the annual energy saving in conjunction with the use of desiccant cooling system was investigated by in-situ measurements, site surveys and simulations. the verified computer model was used for further simulations. it was found that for the use of a minimum ventilation rate of . l/s/person, the use of desiccant cooling system as compared to conventional system saved % of the energy and could achieve the desired space conditions. a parametric study under various ventilation rates indicated that use of desiccant cooling system in wet markets in hot and humid hong kong would lead to energy and energy cost savings, as well as co emission reduction amounting from % to %. the savings were more evident when wet markets were designed for a ventilation rate of l/s/person. furthermore, the actual occupancy profile, and lighting and small power densities determined in this study would be useful for future studies on wet market. in most commercial and residential applications, the space relative humidity is not controlled because conventional air-conditioning systems rely on operating the cold coil at very low effective temperatures to enable the removal of moisture by condensation. as such, the desired space relative humidity can only be achieved by matching the equipment (sensible heat ratio) shr with the building shr, but a perfect match rarely happens. this divergence leads to excessive cooling which increases energy use, and moisture problems which accelerate microbial growth, particularly for subtropical climates like hong kong with very humid outdoor air. in solving the excessive cooling and moisture problems, previous studies [ e ] advocate decoupling of dehumidification from cooling for better humidity control and energy performance. desiccant cooling system, which can actively control the humidity level, is often used for achieving the dehumidification objective. recent studies on desiccant cooling system have been done on optimizing the operating variables for better energy performance [ e ]; developing empirical model for investigation of the system performance [ ] ; improving the control and operation by experimental studies [ , ] ; and widening the application to different types of buildings [ e ] . however, it is noted that they are either restricted to applications where ventilation requirements are set to remove heat generated by people, lighting and equipment, or where moisture removal is not a design intent [ , ] . as for applications where ventilation requirements are set for moisture and contaminates removal, little has been found in extant literature. the recent occurrence of sars (severe acute respiratory syndrome), avian flu and anthracnose in some countries makes environmental health one of the most important elements for an airconditioning system [ ] . in achieving the environmental health objective, ventilation requirement for some premises is not just for heat removal, but for moisture and contaminant removal. the wetmarket in hong kong is one typical example. modernized wet markets in hong kong are housed in airconditioned buildings. they traditionally sell fresh meat, fruits and vegetables, and live animals. live animals include fish, shellfish, and poultry. because water is used to wash the floors, keep the fruits and vegetables fresh, and keep animals alive, wet markets are an extremely damp place. for moisture and contaminant removal, wet markets often require very high ventilation rate and this, combined with the humid outdoor air, increases the latent load and thus a huge amount of energy will be consumed if conventional air conditioning system is used. a gas-fired desiccant cooling system has been installed in a wet market in hong kong which may probably be the first installation of its kind in the world. the actual operating data of the pilot installation will be used to validate simulation predictions. upon successful validation, further simulations will be conducted to evaluate the overall performance of desiccant cooling system as compared to a conventional air-conditioning system. given designers are free to design the ventilation rates they deem proper for wet markets, the influence of ventilation rates on the energy and energy cost savings, as well as co emission reduction of desiccant cooling system will further be investigated. desiccant dehumidification differs from conventional airconditioning system in terms of the thermodynamics of the process air. instead of cooling the air below its dew point to condense its moisture, desiccants attract moisture from the air. desiccant has a vapor pressure lower than the air in its active state. this vapor pressure differential drives the water vapor from air onto the desiccant [ ] . figs. and show the psychrometric processes of the two systems. a conventional system typically admits (outdoor air) oa at state to mix with return air at state r to become mixed air (state ). the mixed air will subsequently be cooled to state followed by a reheating process to become supply air (state ) for achieving the desired space temperature and relative humidity (state r). for the removal of moisture by condensation, state is often conditioned to a very low temperature ( e c dry-bulb) and is close to saturation ( e % relative humidity). in a desiccant cooling system, the latent cooling is performed by desiccant dehumidification whilst the sensible cooling is treated by a cold-coil air handler. the oa at state is first brought into the gas-fired desiccant dehumidifier and is dehumidified adiabatically to state . the dried and hot oa is then pre-cooled by the exhaust air at state r through an air-to-air heat exchanger to state . the pre-cooled oa is subsequently mixed with the return air to state followed by a cooling process at the cold-coil air-handler (state ) to become supply air conditions for achieving the desired space conditions (state r). the exhaust air leaving the air-to-air heat exchanger at state is heated up at the gas burner to become hot air (state ) for regeneration of the desiccant dehumidifier. warm and humid air at state will finally be exhausted to the environment. in the regeneration process of the desiccant dehumidifier, the desiccant wheel rotates slowly into the stream of gas-fired hot air (state ), which raises the vapor pressure of the desiccant above that of the surrounding air. with the vapor pressure differential reversed, water vapor moves from the desiccant to the regeneration air, which carries the moisture away from the system. the schematic of the air flow of the desiccant cooling system is shown in fig. . this study evaluates the overall performance of a gas desiccant cooling system as compared to a conventional air-conditioning for application in a case study wet market. the influence of ventilation requirements on the energy and energy cost savings, as well as co emission reduction of desiccant cooling system will also be evaluated. evaluations were based on in-situ measurements, site surveys and energy simulations. in-situ measurements results were retrieved from the remote monitoring system. the retrieved results include the space air conditions and the year round energy use derived from fans (process and regeneration), chilled water circulating pumps, chillers and burners of the gas-fired dehumidifiers. given key parameters like occupancy, and installed lighting and small power densities are not available; site surveys have been conducted to ascertain these parameters. the in-situ measurements and site surveys results were used for simulation validation to facilitate further simulations. a simulation program, energyplus was adopted to simulate the energy use of the major equipments of the desiccant cooling system for energy analysis. a hypothetical wet market (not the studied wet market) was designed to represent typical modernized wet markets in hong kong to facilitate the evaluations. it was formulated after an the case study market is housed on the ground floor of a storey carport in a public housing estate. car parking spaces are provided from /f to /f with a playground on the roof. the total floor area of the market is m ( . m  . m). the headroom is . m high. it is a typical wet market in hong kong which sells all sorts of fresh produce and live seafood and poultry. the desiccant cooling system installed in this market consists of two parallel systems: a dehumidification system comprises of three units of gas-fired desiccant dehumidifiers installed on the roof dedicated to dehumidify oa, and a chilled water system. the chilled water system is not different from a conventional air-conditioning system which consists of two chillers each of kw cooling capacity and the associated circulation pumps. the capacity is sufficient to cover the sensible and latent loads of the three air-handlers for treatment of mixed air with and without the operation of the desiccant dehumidifiers. this serves as a standby provision to ensure relative humidity of the wet market can always be met. to satisfy the minimum ventilation requirement for non-domestic buildings in hong kong [ ] , the market is designed for a ventilation rate of air change per hour (ach). the building, design and system characteristics of the case study wet market are summarized in table . in-situ measurements and site surveys, with details as discussed below, were adopted to collect data for simulation validation. a remote monitoring system is deployed to monitor the performance of the desiccant cooling system. it can relay commands signals to carry out remote control of the dehumidifiers. the operation of the system can be viewed either locally on site or in the remote office through the internet. the records (air states in hypothesis are with reference to fig. ) can be retrieved by this system which includes space air temperature and relative humidity (state r), dried and hot outdoor air temperature and relative humidity (state ), hourly operation schedule and energy use of major equipments. the monitoring system also enables the set points of relative humidity to be adjusted actively in order to achieve individual needs at a different zone. the system configuration is shown in fig. . the indoor and outdoor air conditions and the energy use of major equipments were retrieved from the remote monitoring system for comparison with simulation results. exemplary results in one summer period are shown in fig. . the average indoor temperature and rh were . c and . % respectively. in the site surveys, the wet market was divided into three zones. each zone was assigned with a responsible person to record to the number of customers as well as stall retailers in every min intervals, and to ascertain the installed lighting and small power densities. occupancy flow measurements were taken on three consecutive days to cover weekdays and weekends during which the occupancy levels were recorded from : to : . the hourly average values are summarized in table . the (installed lighting power density) ilpd was ascertained by counting the numbers and types of luminaires installed in the market. there were altogether four types of luminaires including w florescent lamps, w fluorescent lamps, w spot lights and w light bulbs. the surveyed ilpd is summarized in table . the (installed small power density) ispd was determined by a walk-through survey on the power ratings of the fixed and portable appliances including refrigerators, boilers, cooking devices, and ventilation fans. the surveyed ispd is also summarized in table . energy simulation based on the site survey results (including occupancy, lighting and small power densities and occupation patterns), average space air-conditions as indoor set-point conditions ( . c dry-bulb and . % rh), building envelop details (table ) , and physical geometry of the wet-market were input to energyplus for simulating the annual energy use of the major equipments. the power requirement of the chiller was calculated based on the doe- model. the doe- model is an empirical model and its mathematical expressions are shown in equations ( )e( ), in which capft is the cooling capacity factor; eirft is the energy input to cooling output factor; and eirfplr is the energy input to cooling output factor at part load condition [ e ]. where t cw,s is the supply chilled water temperature; t a,e is the condenser air entering temperature, which is the hourly weather conditions of hong kong in (the typical meteorological year for hong kong [ ] ); plr refers to the chiller's part load ratio; a to f , a to f and a to c are the default coefficients in energyplus. capft, eirft and eirfplr equal to (dimensionless) at reference condition. chiller capacity control is to maintain the designed t cw,s (¼ c) at constant flow condition. the energy consumption of the desiccant dehumidifier was simulated based on a default performance model in energyplus. it is a generic model for determining the leaving dry bulb temperature (t l , c) and humidity ratio (w l , kg/kg dry air) of the process air and the specific regeneration energy (e r, j/kg h o) and regeneration velocity (v r , m/s) of the desiccant wheel shown mathematically in equation ( ). where x is the modeled parameter (i.e. t l , w l , e r and v r ); t e and w e are the process air entering dry bulb temperature ( c) and humidity ratio (kg/kg dry air), which follow the hourly weather conditions of hong kong in (the typical meteorological year for hong kong [ ] ); v is the process air velocity (m/s); and c to c are the default coefficients in energyplus which correspond to the parameter modeled. equation ( ) is valid for the following range of process inlet conditions: dry-bulb temperatures of . ce . c and humidity ratios of . kg/kg to . kg/kg. the output of desiccant dehumidifier is to maintain the leaving process air staying at the designed outlet conditions, which in this analysis is moisture content below . kg/kg dry air. in the simulations, a perfect control and feedback system was assumed such that the output of the equipments would match perfectly with the system cooling demand. table compares the actual and simulated energy use results, illustrating that the difference between the two sets of results is between À . % and þ . %. the difference is considered acceptable considering that the best achievable uncertainty in the measured energy use as estimated based on the kline and mcclintock's equation [ , ] is ae . % (assuming all instruments conform to ashrae standard - ). the comparison of energy breakdown of major equipments in table also shows that their difference is ae %. to check consistency of the two sets of energy breakdown, bivariate correlation was conducted. it was found that the correlation coefficient was . to indicate correlation was significant at the . level ( -tailed). to compare the actual and simulated indoor conditions, their standard errors with the set-point conditions in one summer week period ( st to th july) are compared in table . their standard errors are shown to be comparable, illustrating the simulated results agree well with the actual conditions. given the acceptable range of the difference and the fundamental consistency in the two sets of data, validations are regarded as acceptable to conclude that it is reasonable to adopt simulations for further investigations. further simulations were conducted to compare the energy performance of desiccant cooling system with the conventional system. in this comparison study, the actual occupancy (table ) , the measured lighting and small power densities (table ) , and the installed equipment characteristics of the studied wet market were used in the simulation, but not the space air conditions and ventilation rate for which the ashrae recommendations could not be fulfilled [ ] . according to ashrae [ ] , the indoor air condition in summer should have a wet bulb temperature below c and dry bulb temperature between . c and c. thus for the actual space air temperature of . c, the corresponding relative humidity should be set at %. they were therefore set as indoor set-point conditions in the simulation. whilst for ventilation rate, although there has been no guideline for wet markets, it is noted that the actual rate of ach (corresponds to approximately . l/s/person) is far lower than the ashrae recommended rate for supermarkets of . l/s/person [ ] . given wet markets are much more humid than supermarkets, to avoid the possible microbial growth, ashrae's highest recommended rate for the same air class, i.e. . l/s/person, has been adopted in the simulation. with regards to the equipment characteristics, the desiccant cooling system was assumed provided with the actual installed equipments ( table ), only that our pilot simulation indicated that table installed lighting power density (ilpd) and installed small power density (ispd) in the wet market. with lowering the space relative humidity, the moisture removal rate of the desiccant dehumidifier was too small and thus an electric heater was added to increase the temperature of the regeneration air for supplementing the dehumidification requirements. electric heater was chosen for their common use in buildings in hong kong [ ] . the electric heater capacity was kw determined using energyplus auto size option. the conventional air-conditioning system has been assumed identical to the installed chilled water system (table ) . however, to enable a side-by-side comparison of the energy performance of the two systems, despite the fact that conventional air-conditioning systems control only the space air temperature, it has been assumed in the simulation that chilled water flow rate of the conventional system can be varied to cool and dehumidify the supply air to a level for achieving the desired space air temperature as well as relative humidity; whilst overcooling is assumed offset by electric reheating to maintain the space air temperature. the electric heater capacity was again determined using energyplus auto size option. through hour-by-hour simulations, the year-round space air temperatures and relative humidities achieved by the use of the desiccant cooling and conventional systems were found. the standard error between the simulated results and the set-point conditions for the two systems is summarized in table . it can be seen that their standard errors are comparable to confirm that the two systems have been side-by-side compared based on same space air conditions. energy use of the conventional and desiccant cooling systems for achieving the same space air conditions is compared in fig. , in which gas energy is used for the burner and the other equipments are powered by electricity. the desiccant cooling system is shown to be % more energy efficient than the conventional system. note that this is on the basis that gas is used for regeneration of the desiccant dehumidifier. should "free" thermal energy (for example, waste heat from co-generators or solar energy) is available; the total saving can be increased up to % which is comparable to results of a similar installation for supermarket applications [ ] . further benefits can also be achieved for the difference in energy cost and (effective emission factor) eef between electricity generation and gas burning. the associated energy cost and environmental benefits will be discussed in the later sections. the consumption breakdowns of major equipments of the two systems are compared in table . bivariate correlation was again conducted. it was found that the correlation coefficient was . to indicate correlation was significant at the . level ( -tailed). the results indicate that chillers are the dominant energy consumer for the two systems, accounting for more than % of the total energy use. the evaluations confirm that the simulation results are reasonable, and small energy saving can be achieved by the use of desiccant cooling system. the parametric study is to enable the study of the influence of ventilation requirements on the energy performance, co emission level, and energy cost saving of desiccant cooling system. to provide a basis for the parametric study, a hypothetical wet market representing typical wet markets in hong kong was formulated. a survey of physical characteristics of modernized wet markets in hong kong was conducted. it was found that their areas were ranging from m to , m , with a mean of m ; the aspect ratios (ratio of width to length) were between . and . , with a mean of . ; and the headrooms were between m and . m, with a mean of m. considering the collected data are of equal importance and should be given equal weight, mean values were used to set physical dimensions (w  l  h) of the hypothetical wet market which is m  m  m. given it is common to see humid environment is provided with % outdoor air for control of airborne infectious diseases [ ] , the range of variations has been set between l/s/person at l/s intervals and complete outdoor air flow rate corresponding to l/s/person. in the parametric study, the equipment capacities were determined using energyplus auto size option; only that the rated performance of major equipments including chillers, fans, pumps, burners and desiccant dehumidifiers were assumed identical to those installed at the studied wet market. fig. indicates the energy use comparison between the two systems under various ventilation rate conditions. it is noted that the energy use of both systems is comparable when the ventilation rate is at l/s/person which is consistent with the comparison study result in the earlier section. this again confirms the reliability of the parametric study results. parametric study results revealed that further increase in ventilation rate lead to a steady increase in energy use. however, the rate of rise for the conventional system was higher than that of the desiccant cooling system when the ventilation rate was increased from l/s/person to l/s/person. the results indicate that at a ventilation rate of l/s per person, energy saving of % can be achieved by the use of desiccant cooling system. the significant saving can be explained by the fact that the increase in ventilation rate can offset part of the space cooling load in mild season, but further increase in ventilation rate leads to a sharp increase in space cooling load as shown in fig. . based on the energy consumptions of the conventional (e cr , kwh) and desiccant cooling (e dc , kwh) systems; and the energy split between gas (e dc,gas ) and electricity (e dc,elc ) of desiccant cooling system, the percentage energy cost saving and emission reduction (p) can be predicted based on the use of equation ( ) derived as follows: and: where c is the energy cost saving/co emission reduction between the use of desiccant cooling system and conventional system. using equations ( ) and ( ) becomes: where: w ¼ the ratio of gas consumption to total energy consumption of according to clp and towngas, the electricity and town gas tariffs are $ . /kwh and $ . /kwh respectively, and thus (m) in equation ( ) is . (¼ . / . ). fig. compares the annual energy costs of the two systems. it is noted that there is larger energy cost saving as compared to energy saving for the desiccant cooling system because gas tariff is lower. the saving ranged between % and %, and the optimal saving, as expected, occurred when the ventilation rate was at l/s/person. the environmental impact is assessed based on (carbon dioxide) co saving because the amount of co in the atmosphere accounts for about % of the global warming effect [ ] . the (effective emission factor) eef for electricity generation in hong kong based upon the use of different fuels is estimated to be . kg/kwh, and that for gas is . kg/kwh [ ] . to estimate the amount of co saving, (m) in equation ( ) is . (¼ . / . ). fig. compares the annual co emission level of the two systems. it is noted that similar to energy cost saving, there is larger emission reduction for the desiccant cooling system as compared to energy saving because the effective emission factor for gas is much lower. the reduction ranged between % and %, and again, the optimal reduction occurred when the ventilation rate was at l/s/person. a desiccant cooling system was installed in a wet market in hong kong. in this study, the actual energy performance of the desiccant cooling system was evaluated. evaluations indicated that use of gas desiccant cooling system was an effective and flexible mean for providing active humidity control. further evaluations based on in-situ measurements, site survey and simulation studies were conducted. in-situ measurements provided the actual energy use data for comparison with simulated results and for simulation validation. further simulations based on actual system, equipment and operating characteristics of the studied wet market were conducted for prediction of energy benefits of desiccant cooling system as compared to conventional air-conditioning system, which was found to be %. to evaluate the influence of ventilation rates on the associated energy and energy cost savings as well as co emission reduction of desiccant cooling system, a parametric study under various ventilation rates was performed. the parametric study was conducted based on a hypothetical wet market formulated to represent typical physical characteristics of wet markets in hong kong. the study results revealed that use of desiccant cooling system in wet markets in hot and humid hong kong would lead to energy, energy cost and co emission reduction up to % when the ventilation rate is l/s/person. the results of this study would be useful for establishing essential criteria for the use of supplementary energy source with respect to air-conditioning system design. hvac dehumidification systems for thermal comfort: a critical review energy and peak power savings potential of radiant cooling systems dehumidification equipment advances energy savings potential of chilled-ceiling combined with desiccant cooling in hot and humid climates performance improvement of a gas turbine cycle by using a desiccant-based evaporative cooling system experimental analysis on the dehumidification and thermal performance of a desiccant wheel desiccant wheel regenerated by thermal energy from a microcogenerator: experimental assessment of the performances experimental validation of constant efficiency models for the subsystems of an unconventional desiccant-based air handling unit and investigation of its performance parametric analysis of variables that affect the performance of a desiccant dehumidification system integration of microturbine with single effect exhaust driven absorption chiller and solid wheel desiccant system desiccant cooling for swedish office buildings the impact of desiccant dehumidification on classroom humidity levels modelling and experimental verification of a solarpowered liquid desiccant cooling system for greenhouse food production in hot climates hybrid hvac systems with chemical dehumidification for supermarket applications energy consumption analysis on a dedicated outdoor air system with rotary desiccant wheel hvac systems and equipment, chapter desiccant dehumidification and pressure drying equipment practice note for authorized persons, registered structural engineers and registered geotechnical engineer pnap adm- . buildings department. hong kong sar government an evaluation of empirically-based models for predicting energy performance of vapor-compression water chillers evaluation of the suitability of empirically-based models for predicting energy performance of centrifugal water chillers with variable chilled water flow energyplus energy simulation software. eere, us department of energy generation of a typical meteorological year for hong kong measurement systems application and design experimental methods for engineers ashrae standard . ventilation for acceptable indoor air quality guidelines on performance-based building energy code. electrical and mechanical services department control of airborne infectious diseases in ventilated spaces benchmarking the energy efficiency and greenhouse gases emissions of school buildings in central argentina greenhouse gas emissions in hong kong annual co emission comparison under different ventilation rates the authors wish to thank the commercial & industrial marketing department of the hong kong & china gas company limited for their assistance in preparing this paper. key: cord- -n r pzan authors: lau, joseph tf; kim, jean h; tsui, hi yi; griffiths, sian title: anticipated and current preventive behaviors in response to an anticipated human-to-human h n epidemic in the hong kong chinese general population date: - - journal: bmc infect dis doi: . / - - - sha: doc_id: cord_uid: n r pzan background: the prevalence of self-reported preventive behaviors in response to an anticipated local human-to-human h n transmission outbreak and factors associated with such behaviors have not been examined. methods: a random, anonymous, cross-sectional telephone survey of hong kong chinese adults. results: the public in hong kong is likely to adopt self-protective behaviors (e.g., wearing face mask in public venues ( . %), increasing the frequency of handwashing ( . %)) and behaviors that protect others (e.g., wearing face masks when experiencing influenza-like illness (ili, . %), immediately seeking medical consultation ( . %), making declarations when crossing the border with ili ( . %), complying to quarantine policies ( . %)). multivariate analyses indicated that factors related to age, full-time employment, perceived susceptibility, perceived efficacy of preventive measures, perceived higher fatality as compared to sars, perceived chance of a major local outbreak, and being worried about self/family members contracting the virus were significantly associated with the inclination to adopt self-protective measures. similar analyses showed that education level, variables related to perceived efficacy, perceived major local outbreak and such were significantly associated with various behaviors directed towards protecting others. conclusion: in the event of a human-to-human h n outbreak, the public in hong kong is likely to adopt preventive measures that may help contain the spread of the virus in the community. it has been estimated that . million deaths may result worldwide [ ] . during the sars epidemic, preventive measures were commonly practiced [ ] and a number of these behaviors [ ] [ ] [ ] have been sustained by a large proportion of the public even after the sars epidemic subsided in hong kong [ ] . preventive behaviors such as face mask use and handwashing have been suggested to be effective in the control of the sars epidemic [ ] . understanding the correlates of these behavioral changes would facilitate formulation of policies and campaigns to promote appropriate behavioral responses in the event of a human-to-human h n outbreak. this study investigated the prevalence of self-reported preventive behaviors in response to a hypothetical local outbreak of human-to-human h n transmission. these behaviors included both self-protective measures as well and those protecting others from contracting the virus. factors associated with these behaviors were investigated. the study population was comprised of male and female hong kong chinese adults aged - years. an anonymous cross-sectional telephone survey using a structured questionnaire was conducted in november (n = ). table summarizes the background characteristics of the respondents. random telephone numbers were selected from up-to-date telephone directories. telephone surveys have been used in a number of sars and avian influenza studies [ ] [ ] [ ] [ ] . telephone calls were made by trained interviewers from : pm to : pm each night to avoid over-representation of unemployed persons. for unanswered calls, at least other independent calls were made. the household member whose birthday was closest to the date of the interview was invited to join the study. verbal informed consent was obtained from the respondents and ethics approval was obtained from the ethics committee of the chinese university of hong kong. the response rate, defined as the number of completed interviews divided by the number of eligible households, was approximately %. respondents were asked how likely they would be to adopt the following preventive behaviors if a local human-to-human h n outbreak (defined as "if - new human-to-human transmission of h n cases were to be reported in hong kong") were to occur: face mask use in public venues, increased frequency of handwashing, avoidance of eating poultry, declaration of influenzalike illness (ili) symptoms at border health checkpoints, the seeking of medical consultation immediately with the onset of a fever, face mask use in public venues when having ili symptoms and compliance with any quarantine policies. responses were recoded into categories (yes or no) from a -point likert scale. respondents were asked about perceptions related to human-to-human h n transmission, including perceived modes of transmission (whether human-to-human transmission of the h n virus could occur via respiratory droplets, bodily contact, contaminated objects, eating well-cooked poultry), perceived susceptibility to h n in different groups of people (self, family members, children, adults, older people, health care workers, food handlers, food vendors and the general public), perceived chance of having a major outbreak in hong kong in the next months and perceived efficacy of various prevention measures (quarantine of infected people, face mask use in public venues, frequent handwashing, home disinfection, mass extermination of poultry). respondents were also asked their perceptions of the current availability of effective treatments, whether they believed health outcomes would be worse than those of sars (higher fatality and lower treatment efficacy) and the degree of concern they had about oneself or one's family contracting the virus if - new human-to-human h n were to be reported in hong kong. univariate odds ratios of the associations between the studied perception variables and individual studied preventive behaviors were derived. variables that were significant in the univariate analyses were further analyzed using multivariate logistic regression analyses. statistical significance was set at p = . and spss software version . . (spss inc, chicago, il, ) was used for data analyses. the majority would adopt self-protecting behaviors such as wearing face mask in public venues ( . %), increasing frequency of handwashing ( . %), avoiding eating poultry ( . %), wearing face mask in public venues when having ili symptoms ( . %), seeing a doctor immediately when having a fever ( . %), making declarations at border health checkpoints when traveling with ili ( . %), and full compliance with any quarantine policies ( . %). gender and educational differences were, in general, non-significant, whereas some significant age differences were noted. overall, . % of the respondents would practice all types of protective behaviors ( table ) . the majority of the respondents believed that various groups of people would be highly susceptible to the virus. of the respondents, . % believed themselves and . % believed their family members or the general public to be highly susceptible (table ). over % of the respondents perceived "high"or "very high" efficacy in various preventive practices, and . % perceived mass extermination of poultry as an efficacious measure. of the respondents, . %, . %, . % and . %, respectively, believed that respiratory droplets, contaminated objects, body contacts and eating well-cooked poultry to be transmission modes of the virus (table ) . with regard to the impact of the disease, % believed that there would be a major human-to-human h n outbreak in hong kong in the coming year; . % believed that it would have higher fatality as compared to sars and . % would be very worried about oneself or one's family members contracting the virus if an outbreak were to occur. further, half of the respondents ( . %) believed that effective drugs are now unavailable, fewer ( . %) thought that the efficacy of treatment for this disease would be worse that that of sars (table ) . certain factors were significantly associated with self-protective behaviors at the multivariate level. these include older age, full time employment, higher degree of perceived susceptibility, perceived efficacy of using face masks in preventing the disease, higher degree of perceived efficacy of the preventive measures, perceived higher fatality of h n than sars, anticipation of risk of a major outbreak in hong kong in the coming year, and concern about oneself/one's family in contracting the virus (or = . to . , p < . , table ). perceived efficacy related to mask use, handwashing and mass extermination of poultry, perceived higher fatality rate as compared to sars and worry about oneself/one's family in contracting the virus were significant in the multivariate analysis in predicting perceived higher frequency of handwashing (or = . to . , p < . , table ). having ever been married, perceived susceptibility for food handlers, perceived efficacy of face mask use, perception that well-cooked poultry is a mode of transmission and perceived major outbreak in hong kong were multivariately predictive of avoidance of eating poultry (or = . to . , p < . , table ). multivariate results in table indicate education level, perceived efficacy related to face mask and perceived major outbreak in hong kong in the next year were predictive of anticipated use of face mask in public venues when having ili symptoms (or = . to . , table ); perceived likelihood of a major outbreak in hong kong in the next year and perceived efficacy of disinfection of living quarters were multivariately associated with declaring ili symptoms at cross-border checkpoints (or = . and . , respectively); perceived efficacy of mass extermination of poultry was the only factor predicting immediate doctor consultation when having fever (or = . ). evermarried status, perceived susceptibility related to children, perceived efficacy of face mask use were multivariately associated with intended full compliance with any quarantine policies (or = . to . ). these data indicate that the majority of the hong kong general public would adopt preventive measures, even in the event of - reported human-to-human h n transmissions in hong kong. during the sars epidemic, the prevalence of similar preventive behaviors increased sharply in the initial weeks of the outbreak [ ] . currently, we estimate that reasonably half of the general population is washing their hands over times a day (unpublished data). an even higher frequency of handwashing is expected if the anticipated outbreak occurs. this is consistent with the local government campaigns for promoting handwashing [ ] . handwashing has been efficacious in preventing influenza [ , ] and sars [ ] and the vast majority of the respondents ( %) believed that it would be efficacious in preventing human-tohuman avian influenza. such a belief was, in turn, associated with anticipated higher frequency of handwashing. handwashing may have become a commonly accepted means of preventing infectious respiratory diseases. approximately % of the general population reported face mask use in public venues during the peak of the sars epidemic [ , ] . the majority of the respondents would do so if there was a human-to-human h n outbreak in hong kong. many believed that face mask use in public venues was an efficacious method of human-tohuman h n prevention. however, while . % of the respondents reported that they would report ili symptoms at health checkpoints as required at times of a human-to-human h n outbreak, . % of the respondents did not do so during the period of april to january (during and shortly after the sars epidemic) (unpublished data) [ ] . studies have demonstrated the limited effectiveness of such measures implemented during the sars epidemic [ , ] . it is shown that about % of the general population with ili symptoms during the sars epidemic were wearing face masks [ ] , which is comparable to the results of this study showing that about % would wear face masks. the similarities between various public health responses related to sars and avian influenza are reported and it is speculated that the public is modeling their responses to avian influenza outbreak to those of the sars epidemic. during the sars epidemic, the reported prevalence of face mask use when having ili while traveling abroad was not very high, indicating that a substantial proportion of the general population was not practicing behaviors directed towards protecting others [ ] . this is in contrast to the results of this study, which noted very high proportion of respondents stating their intent to adopt of behaviors directed towards protecting others. the perceived severity of h n may elicit more behaviors directed at protecting others. quarantine was an effective means contributing to the control of sars [ , ] but a comparatively low percentage of the respondents ( . %) believed quarantine to be an effective public health measure for control of avian influenza, and . % of the respondents would not fully comply with government quarantine policies indicates there is still a need for education. as perceived efficacy was or m = odds ratios obtained from multivariate stepwise logistic regression using univariately significant (including marginally significant) variables as candidate variables. . < p < . ; *p < . ; **p < . ; ***p < . . ns = not significant. ---univariately non-significant and was not considered in the multivariate stepwise logistic regression analysis. would worry that it is likely/very likely for oneself or one's family members to contract h n (if - new cases were to be reported in hong kong. gender, age group, and perception that the impacts of human-to-human h n would be worse than that of sars in terms of fatality rate and efficacy of treatment were not associated with any of the dependent variables and were hence not tabulated. or u = univariate odds ratio. or m = odds ratios obtained from multivariate stepwise logistic regression using univariately significant (including marginally significant) variables as candidate variables. . < p < . ; *p < . ; **p < . ; ***p < . . ns = not significant. ---univariately non-significant and was not considered in the multivariate stepwise logistic regression analysis. table : factors associated with anticipated preventive behaviors to protect others if to new human-to-human h n cases were to be reported in hong kong (continued) univariately associated with anticipated compliance with any quarantine policies, dissemination of information about its efficacy may be useful. single respondents were less likely to comply fully with quarantine policies are also generally more mobile. these people may have less support if quarantined, and this should be considered by policy makers. from until the present, the reported fatality rate of avian influenza in human has been over % [ ] , which is markedly higher than the . % case fatality of rate sars [ ] . however, only about % of the study's respondents considered human-to-human h n fatality rate to be higher than that of sars. hence, the actual magnitude of behavioral responses might be even stronger, since we found perceived fatality to be significantly associated with self-protective behaviors. it is particularly interesting to note that while associations with self-protective behaviors such as mask use and handwashing were highly significant, perceived fatality rate in comparison to sars was not significantly associated with any of the behaviors directed to protecting others. therefore, different considerations may be involved in making decisions of whether to practice preventive behaviors, depending on whether such behaviors are self-directed or directed towards others. with full population compliance with quarantine policies, the critical battle front of the avian influenza epidemic would shift to effective hospital infection control. it is unlikely that health care workers will be able to comply to all the stringent occupational guidelines in the event of nosocomial human h n outbreaks. high fatality rates may occur in these health settings if panic or widespread non-adherence to safety measures occur. research, counseling and emergency plans are essential to ensure that front-line health care workers are psychologically prepared and that the operations of health systems will not be disrupted. the public regarded older people, children, health care workers and food vendors as particularly at risk of contracting the virus. during the sars epidemic, it was reported that discriminatory attitudes have been expressed toward some at-risk groups, such as health workers [ , ] . it is worth noting that certain social groups, such as health care workers or food vendors, may be stigmatized similarly during an h n influenza. preventing or minimizing this should thus be focus of future study. approximately one-quarter of the respondents believed that they or their family members would likely/very likely be affected by an h n outbreak whereas approximately one-third of the respondents believed this to be true for the general population. it was reported that during the sars epidemic, the general public worried about themselves or their family members' contracting the virus [ ] . this is expected to be repeated if a human-to-human avian flu outbreak occurs. these perceptions were also associated with anticipated preventive behaviors. many studies have documented severe distress in the community during and after the sars epidemic [ , ] and attention should be given in reduce panic at times of a human-to-human h n outbreak. with the potentially high fatality and infectivity, high level of distress in the public is expected. although prevalence of health-seeking behaviors are usually higher among females than males, gender was not associated with any of the studied behaviors in this study. the health threat in this case may have overridden the aforementioned gender differentials. education level was not associated with self-directed preventive behaviors but was associated with one of the others-directed preventive behaviors. it is possible that altruism is associated with education level. the reverse was true with age. another study indicated that higher age was associated with the more use of preventive measures [ ] . in general, factors related to perceived susceptibility, perceived clinical severity of outcomes (e.g. fatality rate, perceived availability and efficacy of treatments) were associated with anticipated preventive behaviors. such variables are the key factors prescribed by the health belief model (hbm), which stated that adoption of health behaviors is a function of an individual's attitudes and beliefs about the health issue/behavior of concern [ ] . these variables were significant in predicting preventive behaviors related to sars and influenza [ , , ] . the hbm is therefore applicable to understanding behaviors for preventing the spread of emerging infectious diseases. the study has a number of limitations. first, the study was conducted using telephone surveys and some households may not have been included. in hong kong, however, almost all households have telephones [ ] and a large number of local published studies on sars [ ] and avian influenza [ , , ] have utilized this method. second, the response rate of the study was not very high. nevertheless, the response rate was similar to many of other published local studies [ , , ] . with the distributions of - and - year age groups being very comparable to those obtained from the census data ( . % and . %, respectively). the study's gender distribution was also comparable to the census distributions ( . % male and . % female) [ ] . adoption of behavioral responses was self-reported and had not been validated. however, during this pre-outbreak stage, it is unlikely that social desirability strongly biased the reporting of these behaviors. while the results of this study may have meaningful regional policy implications, caution should be given when generalizing the results of this study to other countries. it is less clear whether populations which were relatively unaffected by sars and populations that demonstrated less frequent face mask use and other relevant public health measures would exhibit the same magnitude of intended behavioral responses as the population of hong kong. cultural and perceptions factors (such as perceived efficacy of prevention means) would also result in different prevalence of behavioral responses. international comparisons are therefore also greatly warranted. in the event of a human-to-human h n outbreak, the hong kong public is very likely to adopt strong preventive measures in order to protect themselves and others. the magnitude of these behavioral responses may be even greater than those witnessed during the sars epidemic and would be likely to increase if a high fatality rate or high infectivity rate were reported. these preventive behaviors may be an effective firewall to the continued spread of the virus in the community. surveillance of public responses is an integral part of the government's h n preparedness plan. it should address issues related to the potentially underestimated fatality associated with human h n cases. surveillance should also closely monitor prevalence of important public health behaviors such as quarantine compliance and cross-border preventive measures. up-to-date surveillance information is necessary for the government to implement and make rapid adjustments these public health measures. publish with bio med central and every scientist can read your work free of charge world organization for animal health: update on avian influenza in animals (type h world health organization: cumulative number of confirmed human cases of avian influenza a/(h n ) reported to who probable person-to-person transmission of avian influenza a (h n ) who confirms human-to-human avian flu transmission avian influenza viruses and their implication for human health pattern of mutation in the genome of influenza a virus on adaptation to increased virulence in the mouse lung: identification of functional themes world health organization: ten things you need to know about pandemic influenza pang e: sars related preventive and risk behaviours practised by hong kong-mainland china cross border travellers during the outbreak of the sars epidemic in hong kong sars transmission, risk factors, and prevention in hong kong sars preventive and risk behaviours of hong kong air travellers sars-related perceptions in hong kong. emerg infect dis impacts of sars on healthseeking behaviors in general population in hong kong monitoring community responses to the sars epidemic in hong kong: from day to day avian influenza risk perception, hong kong department of health: health advice on the prevention of influenza anonymous: protecting children from the flu: the flu vaccine is one way... and there's handwashing hand washing decreases risk of colds and flu border screening for sars. emerg infect dis public health interventions and sars spread public health measures implemented during the sars outbreak in singapore modelling potential responses to severe acute respiratory syndrome in japan: the role of initial attack size, precaution, and quarantine world health organization: confirmed human cases of avian influenza a (h n ) world health organization: cumulative number of reported probable cases of sars fear of severe acute respiratory syndrome (sars) among health care workers fear and stigma: the epidemic within the sars outbreak the impact of community psychological responses on outbreak control for severe acute respiratory syndrome in hong kong the health belief model and preventive health behavior prevalence of common chronic pain in hong kong adults discriminatory attitudes towards people living with hiv/aids and associated factors: a population based study in the chinese general population hong kong in figures: population by age group and sex thanks are extended to ms. m.w. chan for her assistance in data collection. the study was supported by the li ka shing institute of health science. the author(s) declare that they have no competing interests. jl conceptualized, oversaw the project, drafted and made final revisions of the manuscript. jhk helped to draft the manuscript and assisted in the statistical analysis. hyt participated in the design and coordination of the study and performed the statistical analysis. sg was involved in the conceptualization of the study andediting of the manuscript. all authors read and approved the final manuscript. the pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/ - / / /prepub key: cord- - ie mx l authors: lam, simon ching; arora, teresa; grey, ian; suen, lorna kwai ping; huang, emma yun-zhi; li, daofan; lam, kin bong hubert title: perceived risk and protection from infection and depressive symptoms among healthcare workers in mainland china and hong kong during covid- date: - - journal: front psychiatry doi: . /fpsyt. . sha: doc_id: cord_uid: ie mx l psychological health among healthcare workers (hcws) has become a major concern since the covid- outbreak. hcws perceived risks of contracting covid- , in relation to depression were investigated. it was hypothesized that perceived high risk of contracting covid- (close contact with cases, inadequate provision of personal protective equipment, insufficient infection control training, and presence of symptoms) would be significant predictors of depression. our cross-sectional survey was completed by hcws across three regions (hubei, guangdong, hong kong) between march to april using convenience sampling. depression was assessed using the -item patient health questionnaire (phq- ). prevalence of depression was . % ( % ci: . - . ), . % ( . - . ) and . % ( . - . ) for hcws in hong kong, hubei and guangdong, respectively. the strongest significant risk factors for depression, after adjustment, were hcws who reported the greatest extent of feeling susceptible to contracting covid- and those who reported the greatest difficulty obtaining face masks. hcws whose family/peers greatly encouraged face mask use had lower prevalence of depression. access to adequate supplies of personal protective equipment is essential for the psychological health of hcws working in stressful environments, through potentially easing their perceptions of vulnerability to covid- . in the immediate aftermath of the outbreak of covid- in wuhan, hubei province, china, a number of tertiary hospitals in adjacent regions moved quickly to establish psychological intervention programs to support healthcare workers (hcws) working with infected, and potentially infected patients ( , ) . this reflects the recognition of the centrality of maintaining optimal psychological functioning among hcws for effective healthcare service delivery, and an implicit recognition that hcws are adversely affected by both physical and psychological stresses ( ) . while the effectiveness of these programs, which include the provision of online courses on dealing with common psychological problems, hotlines to provide psychological assistance, and group-based activities designed to reduce stress,( ) has yet to be evaluated, it has been reported that staff are reluctant to engage with such services ( ) . the question remains as to how it can be best achieved to support the psychological well-being of hcws working in high-risk environments under high-pressure and anti-pandemic situations ( ) . identification of specific psychological difficulties and their risk factors are required for a multi-faceted and nuanced approach to developing effective evidence-based support ( , ) . individual responses may vary as a function of intrapersonal risk perception and resilience, and workplace environmental and organizational factors including training, availability and use of personal protective equipment (ppe) (e.g., protective face wear, gloves, aprons, gowns), ( ) all of which may explain the psychological effects frontline hcws experience during covid- ( ) . the majority of hcws report the protection of one's own physical health as a primary concern in pandemic situations ( ) . indeed, hcws are expected to have adequate workplace protection measures ( ) . the limited availability of ppe due to global shortage and perceived risk of contracting the disease when exposed to infected patients may potentially underscore the onset of mental health symptoms. confidence in infection-control measures, such as the effectiveness of face masks may reduce risk perception and may also mitigate and facilitate an adaptive stress response. however, what remains largely absent from the literature to date, is an examination of actual pandemic situations and if perceived risk (vulnerability and fear of contracting) and mitigations (effectiveness of face masks and knowledge of covid- ) are associated with mental health difficulties, such as depression, in physicians and nurses. here we report findings from an online survey of hcws across three regions of china. we conducted an internet-based survey among hcws in hubei (mainly wuhan), guangdong (from the cities of foshan, shenzhen, zhongshan, zhuhai) provinces of mainland china, and hong kong between march , , and april , , using a convenience sampling method. hcws from a variety of practice settings, including hospitals and clinics were invited using various online platforms (e.g., discussion boards of societies of healthcare professionals, facebook, instagram, wechat). for hcws who accessed the link from the online platforms, studyrelated information was presented and respondents were then asked to indicate their consent preference ("agree" or "not agree"). those who provided consent were then presented with the survey questionnaire (described below). participation was voluntary and anonymous. of the hcws who accessed the link, . % ( / ) in hubei, . % ( / ) in guangdong and . % ( / ) in hong kong agreed to participate. there were no exclusion criteria for the study and data from all participants who provided positive consent were included. the study was approved by the human subjects ethics sub-committee of the special geriatric committee of zhongshan medical association (sgczsma ) and was carried out in accordance with the declaration of helsinki. the -item questionnaire, administered in chinese, was comprised of four sections (see supplementary material). section enquired about demographics and their profession. section enquired about the provision of training and face masks/respirators in their hospital/clinic for the covid- epidemic. section explored the factors leading to or associated with face mask/respirator use, using the health belief model framework, modified from previous studies ( ) . section was the nine-item patient health questionnaire- (phq- ), used for screening and measuring the severity of depressive symptoms ( ) . the outcome of interest was the presence of depressive symptoms, as measured by the phq- , which scores each of the nine diagnostic criteria of the diagnostic and statistical manual of mental disorders, th edition (dsm-iv) for depression from (not at all) to (nearly every day) over the previous two weeks ( ) . with a cut-off score of , phq- had a sensitivity of % and a specificity of % for diagnosing major depression in the hong kong chinese population ( ) . for this study, those who had scores of - were considered to have moderate/severe depression. due to the ongoing nature of the covid- outbreak, we considered four exposures associated with covid- , a priori, as potential risk factors for depression among hcws over the previous two weeks. these included: (i) close contact with confirmed or suspected covid- cases; (ii) inadequate provision of personal protective equipment; (iii) insufficient infection control training; and (iv) having symptoms recently similar to those manifested in a covid- infection. participants also rated on a four-point scale (not at all/to a small extent/to a moderate extent/to a very great extent) the degree (i) they felt susceptible to covid- infection; (ii) the fear of contracting coronavirus; (iii) face masks could prevent them from contracting coronavirus; (iv) difficulty obtaining face masks; (v) family/peers encouraged them to wear face masks; and (vi) if their knowledge about covid- was adequate. we computed the mean phq- scores and the prevalence of phq- -positive depressive symptoms, both with % confidence interval (ci) and compared them across the regions (hong kong versus guangdong and hong kong versus hubei) using cohen's d (for phq- scores) and cohen's w (for the prevalence). we estimated the prevalence of depressive symptoms according to the number of risk factors they were exposed to ( , , , ≥ ), and the health belief related to face mask use. we investigated the association between health belief and depression by building two logistic models, which yielded adjusted odds ratios (ors) and % ci. in model , we entered the six health belief variables separately, each adjusting for sex, educational level, marital status, location, profession, ward/unit, year of hospital work experience (continuous), and the presence of a priori risk factors ( , , , ≥ ). in model all health belief variables were mutually adjusted for, in addition to those already entered in model . because of the small number of responses in the "not at all" category, we combined them with "to a small extent" in all variables and considered the new group as the reference category. based on the regression output, we estimated the prevalence of depression according to health belief variables, stratifying for location. all statistical analyses were performed using stata version . (statacorp lp). p-values were -tailed and those < . were considered statistically significant. the sample characteristics of hcws are presented in table , stratified by region. there were more females than males across each location. the percentage of hcws in hong kong reporting inadequate provision of ppe was high ( . %), and the majority of these hcws also reported insufficient infectioncontrol training ( . %). furthermore, . % of hcws in hong kong claimed they were experiencing covid-like symptoms, greater than those in hubei ( . %) and guangdong ( . %). on average, hong kong hcws had a higher phq- score (mean [sd]: . [ . ] ) compared to those in hubei ( . [ . ] ; cohen's d= . ; p< . ) and guangdong ( . [ . ] ; cohen's d= . ; p< . ). the differences in phq- scores across regions were smaller when controlling for demographic and organizational factors ( table ). there was no meaningful difference in the phq- scores between nurses and physicians within each region (see supplementary table ). more than half of the respondents in hong kong met the criteria for depression ( . %), which was considerably higher than those in hubei ( . %; cohen's w= . ; p< . ) and guangdong ( . %; cohen's w= . ; p< . ). after adjusting for the demographic and organizational factors, the prevalence of depression among hcws in hong kong was still considerably higher ( . %, % ci: . %- . %) than that in guangdong ( . %, . %- . %; p= . ) and hubei ( . %, . %- . %; p= . ) ( table ) . there was a dose-response relationship between the number of a priori risk factors (close contact with covid- cases; inadequate ppe provision; insufficient infection control training; and having covid- -like symptoms) and prevalence of depression. for example, in hong kong, % of the hcws with or risk factors had phq- -positive depression compared to . % among those none of the risk factors (see supplementary table ) . data surrounding health beliefs and personal views of face mask use during covid- in relation to depression, by location, are presented in table . of note, % of those in hong kong who felt susceptible to covid- to a very great extent met the criteria for depression. in the same group, . % of those who felt very fearful of contracting covid- screened positive for depression. the prevalence of depression appeared to higher with the increasing the level of perceived vulnerability and fear and frustration of not being able to obtain face masks (see supplementary table ) . after adjustment for a range of potential confounding factors, those with a priori risk factors had to times the odds of screen-detected depressive symptoms compared to those without (or= . , % ci: . - . for risk factor; . , . - . for risk factors; and . , . - . for or risk factors). among the health beliefs, feeling susceptible and fearful of contracting covid- , as well as difficulty obtaining face masks are associated with higher risk of depression ( table ) . those having the strongest feeling of vulnerability and fear of contracting covid- and those who found it extremely difficult to obtain face masks had approximately three times the odds of being screened positive for depressive symptoms, compared to those who did not have such feeling or problem. interestingly, a strong belief that face mask could be protective was not associated with depression (or= . , % ci: . - . ) while encouragement by family and peers to wear a face mask to a great extent appeared to be a protective factor against depression, after adjustment (or= . , % ci: . - . ). the estimated prevalence of depression according to the various health beliefs are presented in supplementary table . to our knowledge, we are the first group to report the mental health status, specifically depression, among a large sample of hcws across both the pandemic and non-pandemic regions of china as well as hong kong and to examine the relevance of perceived risk and protection from infection in relation to depression. we found that the prevalence of self-reported depression was considerably higher among hcws in hong kong, compared to guangdong and hubei (where covid- was first discovered). the observations in guangdong and hubei are similar to those in other surrounding asian countries during the covid- outbreak ( ) . more than a quarter of hcws in hong kong reported symptoms indicative of moderately severe or severe depression. it is important to note that before the covid- outbreak in hong kong, the prevalence of depression among general population in october , during social crisis, was between . % ( ) . however, findings from a crosssectional study that were reported in a local newspaper, stated that depression was . % ( ) . social unrest is therefore likely to have influenced the prevalence of depression during the covid- outbreak among hcws in our study. not surprisingly, among these hcws the feeling of susceptible to and being fearful of contracting the virus were strongly associated with depression. however, what was emerged as a significant predictor among respondents was reporting great difficulty in obtaining face masks in particular. in line with his, our findings also highlighted the encouragement of face mask use from family and peers as inversely related to depression. while on first inspection, it may appear paradoxical that hcws in hubei had low rates of depression compared to other regions, this pattern of differences in depressive symptoms according to location may be attributable to the timing of survey distribution. it is important to note that the pandemic in hubei, where the virus started in late , authorities had almost gained control of the outbreak at the time of survey administration, which may explain the lower levels of depressive symptoms observed in mainland china, including hubei. however, by this time, the number of diagnosed covid- cases rose sharply in hong kong (from on march to on april ), which may explain the higher prevalence of depressive symptoms among its hcws. although the majority of the responders in hong kong were nurses ( . %), previous research has identified that rates of both depression and anxiety are typically higher in nurses compared to other healthcare workers ( ) . this observation may be reflected in the current study, thereby contributing to this increased prevalence. perhaps of greater concern is the higher levels of concern expressed by hong kong hcws expressing in relation to the inadequate provision of ppe ( . % in hong kong versus . % in hubei and . % in guangdong), which we will now discuss. covid- is transmitted by person-to-person contact or droplet transmission of large respiratory particles that can travel approximately one-meter from the infected individual ( ) . the importance of adequate availability of ppe for staff in hospital settings amidst the covid- outbreak has been documented ( ). ppe, which was once ubiquitous in clinical settings, is now sparse across multiple locations due to the influx of hospitalized covid- patients and also a rapid uptake of their use among the general population ( , ) . if hcws are not suitably protected with ppe, or have inadequate supplies, then this unequivocally jeopardizes the physical health by increasing the actual and perceived level of subsequent risk of infection among hcws who work with confirmed or suspected cases ( ) . while the focus of previous research since the covid- outbreak has been on ppe in relation to the physical health of hcws (contracting the virus), our findings suggest that adequate availability of ppe may influence risk perception, as highlighted by previous research that risk perceptions of susceptibility and severity of infection could predict preventative behaviors such as face mask purchase and use during infectious disease pandemics ( , ) . thus, limited availability of face masks is likely to have heightened perceived risk and the fear of becoming infected with covid- in our sample, particularly if the hcws were in direct, close contact with covid- patients. this increased perception of risk and susceptibility may be further heightened by the number of dependents (children, elderly) associated with the hcws, though we did not obtain this data in our study. there is a reciprocal relationship between state anxiety and increased threat perception ( ) . specifically, cognitive biases, when applied to the processing of threat, increase the level of state anxiety. elevated state anxiety, in turn, amplifies or exaggerates cognitive biases. as a result, cognitive behavior therapy (cbt) may be helpful for improving mental health outcomes during the covid- pandemic, given that it is a well-evidenced treatment for psychological disorders ( ) . however, the evidence for cbt as an intervention in hcws remains preliminary ( ) . larger trials that are specifically tailored to the covid- scenario are therefore needed. as such, pre-existing cognitive vulnerabilities, combined with insufficient ppe (exemplified by the difficulty in obtaining face masks), may result in elevated symptomatology in some hcws. this may partially why only a proportion of hcws manifest with symptoms of depression and anxiety ( ) . in addition, one of the driving factors behind the heightened risk of depression which we observed beyond inadequate ppe, was perceived susceptibility and fear of contracting covid- . this latter finding resonates strongly with a cognitive bias model of understanding psychopathology ( ) . in line with our findings, another recently conducted survey among hcws in hong kong revealed that . % reported being concerned about adequate ppe and that . % were worried about contracting covid- ( ) . although the authors did not link the two factors, they did report a total of . % who met the criteria for depression ( . % with mild and . % with moderate) based on the phq- , the same tool that we employed in our study. the only protective factor that we observed in relation to depressive symptoms across our total sample was that of family and peer encouragement for the application of face masks. this may be seen as an act of solidarity, as the encouragement could imply the help to procure of face masks even though they had been not been provided in sufficient quantities in the hospital and were very difficult to be obtained from the market. our observation is consistent with another study that demonstrated significantly lower depression prevalence among those practicing good personal hygiene techniques such as face mask use and regular hand washing ( ) . this is further consistent with previous research that shows how an individual's social support networks is a key factor for mental health and wellbeing ( ) . in particular, social support networks have been specifically linked to depression levels rather than other psychological outcomes. thus, meaningful social relationships and support are likely to play a pivotal role in the mental health and wellbeing of hcws working in high risk environments during pandemics such as covid- . we acknowledge some study limitations. first, our study relied on a convenience sample thus non-response bias is highly likely and may not be inferred to the whole hcw population. it is possible that the a considerable proportion of the hcws who participated in this survey might want to use the opportunity to express their discontent towards the authority as there continued to be a chronic short supply of ppe in hospitals. nevertheless, the same pattern emerged from all three regions suggesting this was not unique in hong kong. second, all data are subjective but it is important to note that beliefs cannot be objectively ascertained, although these may be subject to biases including social desirability and recall, with the latter being a particularly important consideration in cognitively vulnerable individuals. third, we did not obtain any data pertaining to age of our participants, which may be a potential confounding factor of the relationships assessed, although we have used number of years of experience as proxy. fourth, due to the cross-sectional study design, we are unable to determine cause-effect relationships. finally, the focus of our study was depression but we acknowledge that other psychological outcomes are also important although we did not obtain data on aspects such as anxiety and stress. in conclusion, it is possible that waves of depressive symptoms may be observed in hcws across covid- affected countries when cases are peaking. it is essential that ppe demand is met to minimize and protect the mental and physical health of those who are working tirelessly to control the pandemic. the adverse consequences of insufficient physical protection (such as ppe provision and training on infection control) while having close contact with patients are likely to leave hcws with higher perceived levels of risk in terms of fear and susceptibility of covid- , which manifest in depression. psychological services should be provided to all hcws, and social support from family members and peers are also fundamental to the psychological health of hcws. the datasets presented in this article are not readily available because restrictions imposed by the regulatory authorities. requests to access the datasets should be directed to sl, simon.c.lam@polyu.edu.hk. the studies involving human participants were reviewed and approved by human subjects ethics sub-committee of the special geriatric committee of zhongshan medical association. written informed consent for participation was not required for this study in accordance with the national legislation and the institutional requirements. writing-review and editing; dl: conceptualization, methodology, investigation, writing-review and editing; kl: software, formal analysis, writing original draft as well as review and editing progression of mental health services during the covid- outbreak in china staff mental health self-assessment during the covid- outbreak. east asian arch psychiatry ( ) factors associated with mental health outcomes among health care workers exposed to coronavirus disease understanding and addressing sources of anxiety among health care professionals during the covid- pandemic joint international collaboration to combat mental health challenges during the coronavirus disease healthcare workers' willingness to work during an influenza pandemic: a systematic review and meta-analysis. influenza other respir viruses health care workers' risk perceptions and willingness to report for work during and influenza pandemic the use of facemasks to prevent respiratory infection: a literature review in the context of the health belief model validation and utility of a self-report version of prime-md: the phq primary care study. primary care evaluation of mental disorders. patient health questionnaire the phq- : validity of a brief depression severity measure the patient health questionnaire- for measuring depressive symptoms among the general population in hong kong a multinational, multicentre study on the psychological outcomes and associated physical symptoms amongst healthcare workers during covid- outbreak depression and post-traumatic stress during major social unrest in hong kong: a -year prospective cohort study hong kong happiness declaines, survey shows, with quality of life sinking and 'alarming' results for mental health amid protest crisis caring for the carers: ensuring the provision of quality maternity care during a global pandemic sourcing personal protective equipment during the covid- pandemic as covid- cases, deaths and fatality rates surge in italy, underlying causes require investigation the outbreak of covid- : an overview perceptions related to bird-to-human avian influenza, influenza vaccination, and use of face mask psychosocial determinants of immunization behavior in a swine influenza campaign introduction to the special section on cognitive bias modification in emotional disorders the efficacy of cognitive behavioral therapy: a review of meta-analyses preventing occupational stress in healthcare workers impact on mental health and perceptions of psychological care among medical and nursing staff in wuhan during the novel coronavirus disease outbreak: a cross-sectional study immediate psychological responses and associated factors during the initial stage of the covid- ) epidemic among the general population in china social support and social networks in copd: a scoping review we are grateful to all participants who gave their time to this research. we are also grateful to tvb news magazine for publicizing our study, dr yang lin and ms shun chan, hong kong polytechnic university, for their assistance in data collection, and dr charles opondo, university of oxford, for helpful comments on the statistical analysis. the supplementary material for this article can be found online at: https://www.frontiersin.org/articles/ . /fpsyt. . /full#supplementary-material key: cord- -zaguyxm authors: stephenson, iain; nicholson, karl g; wood, john m; zambon, maria c; katz, jacqueline m title: confronting the avian influenza threat: vaccine development for a potential pandemic date: - - journal: lancet infect dis doi: . /s - ( ) - sha: doc_id: cord_uid: zaguyxm sporadic human infection with avian influenza viruses has raised concern that reassortment between human and avian subtypes could generate viruses of pandemic potential. vaccination is the principal means to combat the impact of influenza. during an influenza pandemic the immune status of the population would differ from that which exists during interpandemic periods. an emerging pandemic virus will create a surge in worldwide vaccine demand and new approaches in immunisation strategies may be needed to ensure optimum protection of unprimed individuals when vaccine antigen may be limited. the manufacture of vaccines from pathogenic avian influenza viruses by traditional methods is not feasible for safety reasons as well as technical issues. strategies adopted to overcome these issues include the use of reverse genetic systems to generate reassortant strains, the use of baculovirusexpressed haemagglutinin or related non-pathogenic avian influenza strains, and the use of adjuvants to enhance immunogenicity. in clinical trials, conventional surfaceantigen influenza virus vaccines produced from avian viruses have proved poorly immunogenic in immunologically naive populations. adjuvanted or whole-virus preparations may improve immunogenicity and allow sparing of antigen. sporadic human infection with avian influenza viruses has raised concern that reassortment between human and avian subtypes could generate viruses of pandemic potential. vaccination is the principal means to combat the impact of influenza. during an influenza pandemic the immune status of the population would differ from that which exists during interpandemic periods. an emerging pandemic virus will create a surge in worldwide vaccine demand and new approaches in immunisation strategies may be needed to ensure optimum protection of unprimed individuals when vaccine antigen may be limited. the manufacture of vaccines from pathogenic avian influenza viruses by traditional methods is not feasible for safety reasons as well as technical issues. strategies adopted to overcome these issues include the use of reverse genetic systems to generate reassortant strains, the use of baculovirusexpressed haemagglutinin or related non-pathogenic avian influenza strains, and the use of adjuvants to enhance immunogenicity. in clinical trials, conventional surfaceantigen influenza virus vaccines produced from avian viruses have proved poorly immunogenic in immunologically naive populations. adjuvanted or whole-virus preparations may improve immunogenicity and allow sparing of antigen. few infectious diseases cause such a huge annual toll of morbidity, mortality, and economic loss as influenza. in addition, influenza can unpredictably emerge to cause pandemics. the spanish pandemic spread around the world within months causing up to million deaths. the transmission of avian influenza h n to at least people during the asian h n epizoonotic period , prompted concerns that the next pandemic is imminent. as highlighted by the recent severe acute respiratory syndrome (sars)coronavirus outbreak, international air travel increases global vulnerability to infectious respiratory pathogens. our ability to combat influenza and its complications depends primarily on vaccination. annual influenza vaccine production is a wellplanned process that takes up to months. current facilities may not be suitable for rapid bulk manufacture of avian influenza virus vaccines in response to a world threat. influenza viruses are enveloped negative-sense rna viruses with a segmented genome belonging to the orthomyxoviridae family. they are classified on the basis of their core proteins into three distinct types: a, b, and c. influenza a viruses infect a range of mammalian and avian species, whereas type b and c are essentially restricted to human beings. influenza a viruses are responsible for annual epidemics and occasional pandemics, whereas influenza b viruses cause outbreaks every - years, but are not associated with pandemics. the main antigenic determinants of influenza a and b viruses are two surface glycoproteins: the neuraminidase and the haemagglutinin, both capable of eliciting immune responses in human beings. the haemagglutinin is involved with receptor binding and membrane fusion. the neuraminidase facilitates cleavage of virus progeny from infected cells, prevents viral aggregation, and aids movement through the mucosal respiratory-tract epithelium. virus strains are classified according to host species of origin, geographic site and year of isolation, serial number, and, for influenza a, by serological properties of subtypes of haemagglutinin and neuraminidase. influenza a h and h subtypes circulating in human beings evolve and undergo antigenic variability continuously. a lack of effective proofreading by the viral rna polymerase leads to a high rate of transcription errors that can result in aminoacid substitutions in surface glycoproteins. virus variants with substitutions in the antibody-binding sites can evade humoral immunity and reinfect individuals. this is termed "antigenic drift". the segmented viral genome allows for a second type of antigenic variation. if two influenza viruses simultaneously infect a host cell, genetic reassortment may generate a novel virus with new surface or internal proteins. pandemic influenza viruses arise by this process of "antigenic shift", when a virus with a new haemagglutinin subtype emerges and spreads efficiently in a naive human population. comparisons of pandemic and interpandemic influenza are shown in table . bird populations. , avian influenza a viruses generally do not cause disease in these natural hosts. the principal site of influenza virus replication in aquatic birds is the gastrointestinal tract resulting in high faecal viral titres and viral transmission in migratory feeding areas. despite the range of virus subtypes, only a few haemagglutinin (h , h , h ) and neuraminidase subtypes (n , n ) have established in human beings and have caused widespread respiratory disease. the haemagglutinin of human influenza viruses preferentially binds to sialic acid receptors containing ␣ , -galactose linkages, whereas avian influenza viruses preferentially bind to those containing ␣ , -galactose linkages. these binding preferences correlate with the predominance of sialic acid ␣ , -galactose linkages on human epithelial cells, and ␣ , -galactose linkages on avian intestinal epithelial cells. [ ] [ ] [ ] although the molecular mechanisms responsible for receptor-binding specificity are poorly defined, it is believed that haemagglutinin of avian origin must acquire human receptor-binding specificity to generate influenza strains capable of sustained human-to-human transmission. site-directed mutagenesis studies have shown that only one or two aminoacid mutations are required for this change. limited passage in human beings of a virus possessing an avian haemagglutinin, such as occurring in asia currently, , may be sufficient to generate such a change. during the th century, an h n virus in , an h n virus in , and an h n virus in caused influenza pandemics. human-avian reassortant viruses seem to have caused the pandemics of and . the h n virus differed by three genes (haemagglutinin, neuraminidase, and the rna polymerase pb ) from the h n virus that infected people between and . the h n virus differed by two genes (haemagglutinin and pb ) from the h n virus that infected people between and . in both cases, the h and h haemagglutinin genes were contributed by avian viruses. sequence analyses of early h and h isolates indicate receptor-binding specificity was altered by a single aminoacid substitution soon after human introduction. since pig trachea contains receptors for both avian and human influenza viruses, and can support replication of viruses of both human and avian origin, it has been suggested that genetic reassortment between avian, swine, and human influenza viruses may occur in pigs, and that they represent a "mixing bowl" for the evolution of human pandemic strains. haemagglutinin and neuraminidase of h n viruses isolated from human beings, poultry, and wild ducks have distinguishable properties. chickens seem to support a separate natural reservoir of influenza viruses, indicating a possible role as intermediate hosts in zoonotic transmission. some avian h viruses established in poultry are capable of two-way transmission between domestic ducks, where they are able to generate multiple reassortants with other cocirculating viruses. these reassortant viruses have haemagglutinin receptor-binding sequences potentially capable of human infection, suggesting that new viruses may emerge directly from the avian pool. the close proximity of people to high concentrations of waterfowl, poultry, and swine in southeast asia, and avian influenza activity, has identified this region as a hypothetical influenza epicentre (figure ). avian influenza viruses generally do not replicate efficiently in human beings, even after experimental infection. before , direct transmission of avian influenza viruses to the human respiratory system was not considered possible. however, it is now recognised that at least some subtypes of avian influenza viruses can replicate within the human respiratory tract. although it is unclear whether the recent reported increase in transmission of avian influenza to people (table ) is the result of heightened surveillance, the geographical expansion of h n poultry outbreaks across asia is an unprecedented and new event. more than confirmed cases of transmission of avian h n virus to human beings has increased the possibility that an avianhuman reassortant virus may emerge to effectively transmit among people. caused by immunity in population result pandemic influenza a antigenic shift: emergence of novel or little or no background immunity high attack rates, excess mortality and re-emerging subtype of influenza a (maybe partial immunity in older morbidity in all age groups people if re-emerging virus) interpandemic influenza antigenic drift: evolution of existing little immunity in infants. partial variable outbreaks or epidemics influenza (a or b) strains immunity in adults by cross-reacting with variable morbidity and antibody to previously seen mortality, usually in elderly and young and related strains (h greatest severity) the first association of avian influenza viruses with respiratory illness in human beings was during when six deaths from human cases of highly pathogenic influenza h n occurred during an outbreak among live-bird markets (table ) . [ ] [ ] [ ] all viral genes were of avian origin, indicating that h n had crossed the species barrier without adaptation or reassortment with human viruses. despite the elimination of ducks, geese, and quail (sources of h n and its donor genes) and cleaning days in the markets, h n viruses have subsequently reemerged in hong kong poultry markets, although hong kong remains free from infection in the h n outbreak across asia. , in late , highly pathogenic h n viruses were isolated from dead waterfowl in hong kong (personal communication, m peiris, university of hong kong), which was notable since h n viruses do not typically cause disease in waterfowl. in february , h n reemerged in hong kong in two family members returning from a trip to china. in , pathogenic h n viruses are causing extensive poultry outbreaks in asia with deaths ( %) of human cases reported in vietnam and thailand. , , in hong kong in , and again in , influenza h n viruses were isolated from children with mild respiratory illnesses. , as with h n , no human-to-human transmission was evident. additional human h infections in china, and detection of antibody to h in human serum samples in china and hong kong suggest that further human h infection has occurred. eurasian h viruses circulating since the late s have been classified into three phylogenetic sub-lineages: g , y (g -like), and y . , those established in live-bird and have also transmitted to swine in hong kong and china. [ ] [ ] [ ] some avian h viruses have acquired receptor-binding characteristics typical of human strains, increasing the potential for reassortment within both human and pig respiratory tracts. in early , outbreaks of highly pathogenic avian influenza h among poultry occurred in the netherlands and extended to belgium and germany. , more than workers involved in control of the outbreak developed viral h n conjunctivitis and a few developed respiratory illness. evidence of limited human-to-human spread, and a fatal respiratory infection, highlighted a significant threat to human health. more recently, cases of avian influenza (h n ) infections have been reported in two cullers during control of an h n poultry outbreak in canada. avian influenza (h n ) seems to have crossed the species barrier from poultry to people for the first time. in egypt in april two infants presenting with mild febrile respiratory symptoms had h n influenza viruses isolated from respiratory samples. as well as h , h , and h viruses, the h subtype has acquired the ability to infect chickens and is rapidly becoming endemic in poultry populations. phylogenetic analyses of h n viruses isolated from wildfowl, showing high nucleotide homology of the internal genes to human h n and h n viruses, suggests these subtypes can transfer genetic material between each other and are potential sources of new strains. h n viruses were responsible for the influenza pandemic and circulated as the only human subtype until when it was replaced by h n subtype. the h haemagglutinin gene, along with the neuraminidase and pb genes, were derived from avian sources. since people born after lack immunity to the h subtype, h viruses pose a pandemic threat to this susceptible population. h viruses continue to circulate in wild ducks, although the conditions required for the re-emergence of human h influenza viruses are unclear. although the virulence of avian influenza viruses has been well studied in avian species, their virulence in mammals is not well understood. infection with avian influenza a viruses in birds causes a wide spectrum of disease ranging from subclinical to overwhelming systemic illness (figure ). both h and h subtypes have the ability to evolve into highly pathogenic forms. although virulence is a polygenic trait, a major contributing factor in birds is the haemagglutinin. cleavage of the haemagglutinin into two subunits is essential for viral infectivity. haemagglutinin from strains of low pathogenicity is cleaved by proteases limited to the respiratory tract of mammalian species and the intestinal tract of avian species. by contrast, haemagglutinin from highly pathogenic viruses can be cleaved by proteases present in a range of tissues, resulting in multi-system infection. structural features at the cleavage site determine the cleavability of the haemagglutinin. the acquisition of multiple basic aminoacids in highly pathogenic h or h haemagglutinin enables cleavage of the protein by these ubiquitous proteases and confers virulence. carbohydrate side chains in the vicinity of the cleavage site may also affect the access of the proteases and hence virulence. other factors in addition to the haemagglutinin cleavage site are likely to contribute to virus pathogenicity in mammals. virulence of mouse-adapted influenza a viruses have been associated with the interferon antagonist properties of the ns protein or the ability of the neuraminidase glycoprotein to sequester circulating plasminogen and promote haemagglutinin cleavage. balb/c mice [ ] [ ] [ ] [ ] and ferrets are useful mammalian hosts for the evaluation of human h n pathogenesis. in these mammalian hosts, the multibasic aminoacid motif in the haemagglutinin is necessary but not sufficient for virulence. , , a single aminoacid substitution in pb is associated with high pathogenicity of human h n viruses in mice although substitutions in other gene products are likely to play a part. in human h n infection, disease progression to respiratory failure is unusually severe, with features of haemophagocytosis, leucopenia, and multiple organ failure. , , in-vitro infection of human macrophages with h n human viruses induces high levels of cytokines compared with some human virus strains. in pig respiratory epithelial cells, the h n human viruses were also shown to be relatively resistant to the inhibitory effects of host antiviral cytokines such as interferons. thus, the severity of h n infection in people is likely to be related to the induction of excessive proinflammatory responses that exacerbate tissue injury. it has been suggested that the nonstructural gene has a role. gene sequence analyses of the pandemic virus, which displayed enhanced virulence in human beings has not yet uncovered molecular determinants previously associated with influenza virus virulence. , the molecular determinants and gene constellations that confer virulence of avian, swine, and human viruses, and the circumstances under which virulent phenotypes emerge remains unclear. understanding the basis of virulence is important for vaccine design, particularly of live vaccines, so that viruses can be attenuated. current inactivated influenza vaccines are produced from virus grown in embryonated hens' eggs, and are of three types: whole-virus, "split-product", or subunit "surface-antigen" formulations. whole-virus vaccines are associated with increased adverse reactions, especially in children, and are little used. most influenza vaccines are split-product vaccines, produced from detergent-treated, highly purified influenza virus, or surface-antigen vaccines containing purified haemagglutinin and neuraminidase. vaccines are usually trivalent, containing g each of two influenza a subtypes (h n and h n ) and one influenza b strain. vaccines elicit a relatively strain-specific humoral response, have reduced efficacy against antigenically drifted viruses, and are ineffective against unrelated strains. the who reviews vaccine composition biannually and updates antigenic content depending on prevalent circulating subtypes to provide antigenically well-matched vaccines. protective efficacy of - % in healthy young adults is obtained when there is a good antigenic match between the vaccine and circulating strains. vaccination of the elderly is associated with - % reductions in hospitalisation for pneumonia and influenza, - % reductions for all respiratory conditions, and - % reductions in all-cause mortality. new influenza vaccines must elicit protective immunity. the haemagglutinin-inhibition test is most commonly used for the detection of antibody to influenza, although single radial haemolysis (srh) may also be used, since both are correlated with immune protection. , in the european union, interpandemic influenza vaccines should fulfil certain criteria, prepared by the committee for proprietary medicinal products (cpmp), which are usually assessed by haemagglutinin-inhibition tests in limited annual clinical studies (panel ). in the event of pandemic influenza, vaccine demand would soar. savings made using monovalent rather than trivalent vaccine ( g haemagglutinin per dose instead of g) would possibly be offset by a two-dose schedule, increased demand, and difficulties with production of egg-grown viruses. new developments include the use of mammalian cell lines to culture influenza virus for vaccines to provide increased flexibility of production at times of heightened demand. immunopotentiating effects of adjuvants and whole-virus vaccine may increase antigenicity, allowing dose content reduction enabling maximum efficient use of limited supplies. the population immune status in a pandemic situation differs from that seen during the interpandemic period. at the onset of the previous pandemics, younger adults were immunologically naive to the new strains, whereas older populations may have been primed by previous infections of related strains that circulated in earlier times. global immune susceptibility to avian influenza subtypes would be expected. the quantity of antigen required to elicit satisfactory immune responses in naive individuals is unclear since few studies have been done after the emergence of a novel virus. current events suggest the urgent need to develop a clearly defined strategy for clinical assessment of safety and immunogenicity of pandemic vaccines. in and , the emergence of influenza a/new jersey/ and a/ussr/ / (h n ) triggered pandemic alerts, and afforded the opportunity for vaccine trials in immunologically naive and primed populations. a series of whole-virus vaccine studies [ ] [ ] [ ] [ ] [ ] reported differences between naive populations (those aged years and not exposed to previous h n strains) and primed populations (older than ). in naive patients, if one dose of vaccine was administered, large doses (in excess of g haemagglutinin) were required to fulfil cpmp criteria. however, if two doses of vaccine were given, lower antigen doses ( g) were needed. whole-virus vaccine was significantly more immunogenic than subunit or split-product vaccines. in primed patients, as is the case during interpandemic periods, no difference in immunogenicity between whole-virus vaccine and subunit or split-product vaccines was reported. however, a consistent finding was that whole-virus vaccine was associated with increased reactogenicity, particularly in children, who developed febrile complications even with low doses. although licensed for use in human influenza vaccines, aluminium salts are rarely used since studies have indicated little clinical benefit. however, encouraging findings were more recently reported in a study of whole-virus a/singapore/ / (h n ) vaccine in immunologically naive people. monovalent alumadjuvanted vaccine containing either · , · , or · g h haemagglutinin per dose was compared with unadjuvanted whole-virus g vaccine. although a single dose of any vaccine was unable to elicit responses associated with protection, a second dose of vaccine boosted responses to mean geometric increase in antibody > · (> in the у years group) number of seroconversions or significant rises in anti-haemagglutinin antibody (ie, four-fold increase in post-vaccination hi titre or % increase in srh zone) should be > % (> % in the у years group) proportion of patients achieving a seroprotective hi titre of у / , or srh titre of > mm post vaccination should be > % (> % in the > years group) rates that fulfilled cpmp licensing criteria across all doses, suggesting that up to an eight-fold reduction in antigen content could be achieved with the addition of alum (figure ). since influenza a viruses possess a segmented genome, simultaneous infection of eggs with two different viruses may result in reassortment of segments to produce a desired vaccine seed strain. the influenza a virus components of annual influenza vaccines are typically derived from egggrown reassortment viruses that have the relevant haemagglutinin and neuraminidase genes of the antigenically relevant strain, and the six remaining gene segments from a/puerto rico/ / (h n ). these pr/ / segments confer high growth properties in eggs favoured for inactivated vaccine production. this process requires large numbers of eggs, and in many companies lacks the flexibility to respond rapidly to a pandemic event. highly pathogenic h and h viruses cannot be grown in large quantities because they are lethal to chicken embryos. such pathogenic strains also impose regulatory and safety issues. as the multibasic sequence cleavage site is believed to contribute to the pathogenesis of human h n infection, vaccine preparation from wild-type h n virus would require heightened biocontainment to protect workers and eliminate the possibility of environmental contamination and infection of susceptible animals. thus, several approaches have been attempted for avian influenza vaccine development. these include: ( ) the production of inactivated vaccine from wildtype virus; ( ) the selection of an antigenically related nonpathogenic vaccine strain; ( ) the use of baculoviruses to express recombinant haemagglutinin; ( ) dna-based vaccines; ( ) the use of plasmid-based reverse genetics systems to construct vaccine seed strains possessing attenuated haemagglutinin; and ( ) plasmid-based reverse genetic systems to construct attenuated donor strain recombinants. reverse genetics is likely to produce the most rapid response in an emerging pandemic. much of the preclinical and clinical development of highly pathogenic avian influenza vaccines has used h virus as a model. after the h n outbreak, inactivated vaccines from wild-type a/hong kong/ / (h n ) virus were prepared in the uk and the netherlands. , whole-virus vaccine was effective in protecting mice against lethal challenge with h n virus. conventional surface-antigen vaccine was poorly immunogenic in chickens and did not protect against lethal dose challenge, although an iscom formulation (antigen as immune-complex stimulators) boosted immune responses and protected against lethal h n challenge. because the use of highly pathogenic strains has safety restrictions, the selection of a surrogate non-pathogenic virus capable of evoking crossreactive immunity to the hong kong h n viruses was investigated. both a/duck/hokkaido/ / (h n ) and a/duck/singapore/ (h n ) have haemagglutinin proteins antigenically similar to a/hong kong/ / (h n ) and were used in experimental vaccines. , although antibody titres to h n induced by a/duck/ singapore (h n ) vaccine were four-fold lower than the homologous strain, inactivated whole-virus vaccine , and alum-adjuvanted subunit vaccine were capable of protecting mice against lethal h n challenge. although attempts to reassort a/duck/singapore (h n ) with a/pr/ / to produce a high-growth virus suitable for vaccine production failed, conventional and mf -adjuvanted a/duck/ singapore/ (h n ) surface-antigen vaccines were clinically assessed in a randomised phase i trial. two doses of · , , or g h haemagglutinin were given weeks apart. antibody responses were measured by haemagglutinininhibition, virus microneutralisation, and srh. although both vaccines were well tolerated, non-adjuvanted vaccine was poorly immunogenic, with only one of ( %) recipients seroconverting by haemagglutinin-inhibition and srh h n , and four ( %) by microneutralisation and srh h n after two g doses. the addition of mf gave significantly higher antibody responses (figure ), and two doses achieved seroconversion rates of / ( %), ( %), ( %), and ( %) by haemagglutinin-inhibition, microneutralisation, srh h n , and srh h n , respectively. antibody titres by srh to h n were about half those to h n , showing the need for close antigenic matching between vaccine and pandemic strains to ensure maximum vaccine efficacy. antibody responses after h n revaccination months later were boosted significantly above those achieved after two doses. it is desirable for vaccines to boost responses after initial priming, since second waves occur - months after the first pandemic wave of infection. one problem in assessing vaccine responses was the insensitivity of the haemagglutinininhibition test, routinely used in assessment of influenza vaccines, for the detection of antibody to h when compared with neutralisation tests. , haemagglutinin-inhibition relies on the ability of antibody to disrupt the haemagglutinin-sialic-acid-receptor binding interaction between virus and erythrocytes. if the erythrocytes used in the test are not optimised for expression of ␣ , galactose linkages that are necessary for avian influenza virus binding, the test is insensitive. however, there are no recognised clinical correlates of immune protection for neutralisation antibody. it was only possible to assess vaccine responses with respect to cpmp licensing criteria after development of a specific srh assay. a modified haemagglutinin-inhibition test, using enzymatically altered turkey erythrocytes or horse erythrocytes, was developed to increase the sensitivity for detecting antibody to avian influenza virus antigens. an alternative to egg-derived vaccines involves the use of haemagglutinin protein expressed in insect cells by recombinant baculovirus. potential difficulties include the use of uncleaved rather than cleaved haemagglutinin and differences in glycosylation in insect cells that may effect immunogenicity. nonetheless, antibody responses to - g doses of recombinant h and h antigens are similar to those induced by licensed vaccines. , baculovirus-derived h and h haemagglutinin vaccines protect against lethal virus challenge in chickens, even when the haemagglutinin sequence homology differs by up to %. however, when clinically assessed in people, a recombinant baculovirus-expressed h vaccine was suboptimal. even after two doses of g, only % subjects seroconverted by microneutralisation, suggesting improvements in immunogenicity are needed. reverse genetics systems can be used to generate attenuated avian influenza viruses, and are likely to prove pivotal in pandemic vaccine development. the appropriate haemagglutinin and neuraminidase genes from a virus can be cloned and, if necessary, the haemagglutinin may be attenuated by removal of the multi-basic cleavage site sequence, and inserted into plasmids. the plasmids are transfected into a cell line together with plasmids encoding the internal genes from the a/pr / virus to generate an appropriate non-pathogenic vaccine seed strain. vaccine candidates expressing the target haemagglutinin from highly pathogenic viruses could potentially be produced within weeks of an emerging event. recombinant h viruses showing desirable properties for h vaccine formulation-including loss of egg lethality, virulence, and infectivity in animal models-have been produced, , although one attenuated recombinant virus showed limited neurovirulence in mice. reverse genetics is thus capable of generating attenuated viruses from pathogenic strains suitable for vaccine production with only limited enhancement of biosecurity measures and using pre-existing equipment and facilities. it should also be possible to prepare panels of reassortant viruses and vaccine seed candidates containing target genes of potential pandemic viruses in advance of any specific threat. however, there are regulatory, safety, and legal problems to overcome before the technology can be used for vaccine development. mammalian cell lines (eg, vero cells) used for transfection must be of certified quality for human vaccine production. viruses generated by reverse genetics may be considered to be "genetically modified organisms", imposing local and national safety regulations regarding research and development. in addition, intellectual property rights on reverse genetics technology are held, and licences may need to be granted for commercial use of vaccines. inactivated influenza vaccines are poor inducers of cytotoxic t-cell (ctl) responses, which aid in recovery from influenza infection. it has been suggested that crossreactive immunity to several influenza virus subtypes could be induced by ctl responses to conserved epitopes in internal proteins. dna vaccines integrate gene sequences for the antigenic protein of interest into bacterial plasmids that are inoculated into the host. the expression of plasmid dna produces the antigen in its natural configuration, which is more likely to stimulate neutralising antibody and undergo hla class i expression inducing ctl responses. h and h haemagglutinin-expressing dna vaccine protects mice and chickens against lethal dose virus challenge. , dna vaccine expressing conserved internal proteins including nucleoprotein give partial protection to mice against h n infection. intradermal dna influenza vaccines are beginning clinical evaluation. iscom-formulated h n vaccine can induce ctl responses and greater longer-lasting antibody responses than conventional vaccine. it offers broad protection against virus challenge with h , h , h , and virulent h viruses in mice. iscom vaccines are tolerated in human beings and induce broad ctl and rapid humoral responses. mucosal delivery of inactivated influenza h n vaccine adjuvanted with modified heat-labile enterotoxin from escherichia coli induces b-cell-dependent heterosubtypic immunity against lethal h n virus challenge in mice. in the absence of an antigenically matched vaccine, alternative vaccine strategies that induce crossreactive immunity by iscom, dna, or mucosal vaccines may provide useful firstline defence against an emerging pandemic strain. since h viruses do not have a multibasic haemagglutinin cleavage site, they show low pathogenicity for avian species and may be grown to high titres in eggs. both g -like (a/hong kong/ / ) and y (g -like; a/hong kong/ / ) h n viruses are capable of human infection. , for an effective h vaccine strategy, an understanding of the relative immunogenicity and crossprotection induced by these lineages is required. although infection of mice with g or g group h viruses did not evoke detectable crossreacting neutralising antibody, they were protected from subsequent rechallenge with the homologous or heterologous virus lineage. whole-virus g h vaccine produced crossreactive antibody responses to both g and g viruses, and protected mice against rechallenge with either virus. by contrast, whole-virus g h vaccine induced homologous antibody titres only and was able to protect against g challenge, but showed reduced protective efficacy against the heterologous g lineage. here, a single dose of h vaccine induced adequate immune responses in mice, by contrast with findings with h n vaccine that required a two-dose schedule to elicit adequate immune responses. , since some y (g -like) h viruses do not grow well in eggs, an a/pr/ / reassortant has been produced. one dose of inactivated g /pr vaccine protected mice against g challenge. two doses of vaccine increased antibody responses capable of protecting mice against both g and g h challenge. whole-virus and subunit a/hong kong/ / (h n ) vaccines were clinically evaluated in the uk. adults were randomly assigned two doses, administered weeks apart, of · , , or g h haemagglutinin content. although well tolerated, whole-virus vaccine was more reactive, in keeping with h n vaccines. there was little detectable crossreactive immune response to an antigenically distinct g h virus (unpublished findings). more than % of the prevaccination serum samples showed reactivity to h n by neutralisation and haemagglutinin-inhibition, suggesting preexisting crossreacting antibody from exposure to earlier haemagglutinins. it is unlikely that h influenza has circulated widely in the uk. further serological testing correlated h reactivity with antibody responses to h , but not h or h haemagglutinin. people with baseline reactivity to h were born before , and thus had been potentially exposed to h during its period of circulation in human beings. subjects were immunologically divided into naive and primed recipients. in truly naive subjects, one dose of either vaccine was poorly immunogenic. although whole-virus vaccine was more immunogenic than subunit vaccine, two doses still left a significant number of vaccinees with serological responses below the protective threshold (table ) . among primed individuals, one dose of either vaccine boosted anti-h responses, fulfilling cpmp criteria. since the second dose was of questionable value, to preserve limited vaccine supplies during the first wave of an emerging pandemic, different schedules in different populations could be considered. a german study among - year-olds reported one dose of g whole-virus vaccine a/hong kong/ / (h n ) capable of fulfilling at least one cpmp criterion and that a second dose of vaccine significantly improved responses. however, age-related responses or the effect of pre-existing reactivity to h n were not analysed. in keeping with the h n experience, alum-adjuvant allowed a reduction in h content to · g per dose while maintaining immunogenicity. intranasally delivered live, attenuated cold-adapted influenza vaccines elicit systemic and local mucosal immune responses and display protective efficacy. attenuated cold-adapted strains are generated by reassortment between a wild-type virus expressing target haemagglutinin and neuraminidase, and a cold-adapted donor such as influenza a/ann arbor/ / (h n ). donor strains are cold adapted, temperature-sensitive, and attenuated. these properties are associated with polygenic mutations. these live attenuated viruses display high levels of phenotypic and genotypic stability and are not transmissible to close seronegative contacts. both attenuated h n and h n /ann arbor cold-adapted recombinant viruses have been generated and are seen to be non-pathogenic in mammalian and chicken models. , concerns over the generation of a reassortant between a live virus vaccine containing an avian influenza virus and a co-infecting human strain, and the possibility of spontaneous genetic change may limit the use of such vaccines in the interpandemic period. while current intramuscular influenza vaccines are effective at inducing relatively strainspecific serum haemagglutination-inhibition igg, they are poor at stimulating secretory iga in nasal wash fluid. , as secretory iga exhibits potential heterotypic crossreactivity to influenza virus strains at the point of entry, , live attenuated virus vaccines may offer wider protection against vaccinedrifted variants that could be advantageous once a pandemic is underway. specific influenza antiviral agents are available for early treatment and prophylaxis of influenza. the adamantanes, amantadine and rimantadine, have been available for more than years and inhibit strains of influenza a including nonhuman subtypes. however, rapid emergence and transmission of drug-resistant virus after treatment may render prophylaxis ineffective. the genetic basis for resistance seems to be single aminoacid substitutions in the viral m ion channel. the h n strains isolated from poultry and human cases in had genotypic changes in the m gene associated with resistance, suggesting these agents would be of little clinical value should these strains become capable of humanto-human transmission. neuraminidase inhibitors, such as zanamivir and oseltamivir, are effective in prevention studies and are highly active against a broad range of influenza a viruses of both human and avian origin, including amantadine-resistant strains. although strains with reduced susceptibility to neuraminidase inhibitors have been isolated after sequential passage of virus in presence of drugs, clinically significant resistant strains have not, as yet, been identified. antiviral drugs may be of benefit in protecting individuals in essential services whilst waiting for an effective vaccine to be prepared; however, supply and cost issues would limit their effect on the course of a pandemic. a sufficiently large supply of antivirals to curb pandemic influenza would require international or need for robust surveillance programmes in human and animal populations and sharing of information between animal and human surveillance systems surveillance information to be open and shared in a timely fashion to assess potential threats potential pandemic strains come from animal reservoir. improved understanding of the antigenic and molecular associations between potential pandemic strains of same subtype improved understanding of immunogenicity against drifted avian influenza strains is required as the ability to generate broad crossprotective immunity is desirable in vaccine candidate. intellectual property rights of attenuated viruses produced by reverse genetics must be addressed in advance because licences for commercial use may be required vaccine virus candidate needs to be able to grow well in eggs (or approved cell culture) to improve ability to respond rapidly to emerging threat improved understanding of virulence determinants in mammalian models to be able to attenuate viruses used for vaccine manufacture safety of virus handling for workers involved in preparation of vaccine to assess and approve mammalian cell lines of human vaccine quality ensure that reagents from animal sources are transmissible spongiform encephalopathies compliant "reverse genetics" generated viruses are labelled as genetically modified organisms-implications for national and local regulatory authorities clinical assessment of vaccines derived by reverse genetics ability to organise antigenicity studies rapidly in response to emerging threat may require prepared approved protocols that can be readily adapted. improvement in assessment of antibody responses to avian influenza vaccines to establish licensing criteria standardisation of assays for detection of neutralising antibody to avian influenza establish correlates of immune protection of neutralising antibody whole-virus vaccine more immunogenic than subunit or split-product vaccine in immunological naive populations (h n , h n ) two doses of vaccine required in immunologically naive populations, the first to prime and the second to boost responses (h n , h n , h n , h n ) in primed populations, a single dose of vaccine can potentially induce responses associated with protection (h n , h n , h n ) addition of adjuvants such as mf and aluminium salts have the potential to significantly enhance immunogenicity and spare antigen use (h n , h n and h n ) avian haemagglutinin (h and to a lesser extent h ) seems to be less immunogenic in people than h and h assessment of antibody responses to avian influenza may require additional serological methods other than the standard haemagglutinininhibition test (h n ) potential crossreactivity with pre-existing antibodies complicates interpretation of immune responses in people (h n ) need to develop understanding of improving vaccine candidates to enhance heterosubtypic crossreactivity and protection need to assess vaccine candidates in advance of pandemic to identify difficulties and establish dosing schedules in different populations national stockpiling before the onset of such an event; this would require considerable expense, and vaccination is likely to remain the principal means of combating pandemic influenza. although pandemic planning and understanding is greater since the first h outbreak in , our ability to respond rapidly remains less than optimal. the asian h n epizoonotic outbreak indicates the urgent need for vaccines against avian influenza viruses. however, regulatory and safety considerations confront their development (panel ). it is necessary to improve our understanding of the virulence determinants in mammalian systems to be able to attenuate viruses to select appropriate and safe vaccine strains that can generate broad crossreactivity. national and international authorities must urgently confront regulatory issues to allow production and clinical assessment of newly generated virus vaccine candidates. there are important observations from our clinical experience with vaccines for pandemic influenza (panel ). despite increased reactogenicity, the greater immunogenicity of whole-virus vaccines could be beneficial in a pandemic. vaccines containing avian h and h haemagglutinin seem to be less immunogenic in human beings than vaccines based on h and h haemagglutinin. whether this is a general event associated with avian subtypes is at present unclear. enhancement with mf or alum salts may provide best antigen use and enhance immunogenicity. overall, so far, clinical trials of avian influenza vaccine candidates have given disappointing results. it remains to be seen how plasmid-derived reverse-genetics influenza vaccines will perform once regulatory hurdles have been overcome. we have no conflicts of interest. chronicle of influenza pandemics avian influenza (h n ) in patients in vietnam the textbook of influenza evolution and ecology of influenza a viruses characterisation of a novel influenza haemagglutinin h : criteria for determination of influenza a subtypes single amino acid substitutions in influenza haemagglutinin change receptor binding specificity receptor specificity in human, avian and equine h and h influenza virus isolates receptor specificity of influenza a viruses correlate with agglutination of erythrocytes from different animal species early alterations of the receptor binding properties of the h , h and h avian influenza virus haeamgglutinins after their introduction into mammals avian to human transmission of the pb gene of influenza a virus in the and pandemic influenza in pigs and their role as the intermediate host the surface glycoproteins of h influenza viruses isolated from humans, chickens and wild aquatic birds have distinguishable properties characterisation of h subtype influenza viruses from the ducks of southern china: a candidate for the next influenza pandemic in humans? an influenza epicenter? replication of avian influenza viruses in humans avian influenza isolated from a woman with conjunctivitis human influenza a h n virus related to a highly pathogenic avian influenza virus clinical features and rapid viral diagnosis of human disease associated with avian influenza a h n virus antibody responses in individuals infected with avian influenza a (h n ) viruses and detection of anti-h antibody among household and social contacts characterization of the surface proteins of influenza a h n viruses isolated from humans in - human infection with influenza h n lack of evidence for human-to-human transmission of avian influenza a (h n ) viruses in hong kong re-emergence of fatal human influenza a subtype h n disease antigenic characterization of recent avian influenza a h n viruses isolated from humans avian influenza a virus (h n ) associated with human conjunctivitis and a fatal case of acute respiratory respiratory distress syndrome transmission of h n avian influenza a virus to human beings during a large outbreak in commercial poultry farms in the netherlands influenza a (h n ) in hong kong special administrative region of china avian influenza h n infection in humans: urgent need to eliminate the animal reservoir-update cases of influenza a (h n )-thailand avian influenza virus a (h n ) circulating among humans in egypt an update on avian influenza in hong kong in h n influenza viruses isolated from geese in southeastern china: evidence for genetic reassortment and interspecies transmission to ducks discovery of man infected by avian influenza virus seroprevalence of antibody to h n viruses in poultry workers of hong kong molecular characterization of h n influenza viruses: were they the donors of the internal genes of h n viruses in hong kong influenza a viruses: relationship between h n relationship between h n and h n human isolates emergence and control of zoonotic ortho-and paramyxovirus diseases cocirculation of avian h n and human h n viruses in pigs in southern china seropidemiological evidence of avian h , h and h influenza viruses transmission to pigs in south eastern china characterisation of a human h n influenza virus isolated in hong kong molecular evolution of h influenza viruses from poultry in south eastern china: prevalence of h n influenza viruses possessing seven a/hongkong/ / h n -like genes in poultry transmission of eurasian avian h influenza virus to shorebirds in north america enhancement of the infectivity of influenza a and b viruses by proteolytic cleavage of the haemagglutinin polypeptide proteolytic cleavage of influenza virus haemagglutinins: primary structure of the connecting peptide between ha and ha determines proteolytic cleavability and pathogenicity of avian influenza viruses inhibition of interferon-mediated antiviral responses by influenza a viruses and other negative-strand rna viruses a novel mechanism for the acquisition of virulence by a human influenza a virus a mouse model for the evaluation of pathogenesis and immunity to influenza a (h n ) viruses isolated from humans molecular correlates of influenza a h n virus pathogenesis biological heterogeneity, including systemic replication in mice, of h n influenza a virus isolates from humans in hong kong pathogenesis of avian influenza a h n viruses in ferrets molecular basis for high virulence of hong kong h n influenza a viruses pathogenicity and antigenicity of a new influenza a (h n ) virus isolated from duck meat induction of proinflammatory cytokines in human macrophages by influenza a h n viruses: a mechanism for the unusual severity of human disease? lethal h n influenza viruses escape host anti-viral cytokine responses origin and evolution of the spanish influenza virus heamagglutinin gene characterisation of the spanish influenza virus neuraminidase gene vaccine production antigenic drift and efficacy of influenza virus vaccines efficacy/clinical effectiveness of inactivated influenza virus vaccines in adults determinants of immunity to influenza infection in man correlation between rate of infection and pre-existing titer of serum antibody as determined by single radial haemolysis during an epidemic of influenza a/victoria/ / note for guidance on harmonisation of requirements for influenza vaccines, cpmp/bwp/ / . circulaire no - : - . london: committee for proprietary medicinal products development of a vero cell-derived influenza whole virus vaccine antibody responses and reactogenicity of graded doses of inactivated influenza a/new jersey. whole virus vaccine in humans summary of influenza virus vaccine trials in adults trials of influenza a/new jersey/ virus vaccine in normal children: an overview of age related antigenicity and reactogenicity clinical studies of monovalent inactivated whole virus and subunit a/ussr/ (h n ) vaccine: serological responses and clinical reactions responses of volunteers to inactivated influenza virus vaccines lack of adjuvant effect of alpo on purified influenza virus haemagglutinin in man pandemic preparedness: lessons learnt from h n and h n candidate vaccines avirulent avian influenza virus as a vaccine strain against a potential human pandemic vaccine against h n influenza iscom vaccine induced protection against a lethal challenge with a human h n influenza virus safety and antigenicity of nonadjuvanted and mf -adjuvanted influenza a/duck/singapore/ (h n ) vaccine: a randomised trial of two potential vaccines against h n influenza boosting immunity to influenza h n with mf -adjuvanted h n a/duck/singapore/ vaccine in a primed human population pandemic planning serological evidence of human infections with avian influenza viruses detection of antibody to avian influenza (h n ) virus in human sera by using a combination of serological assays sialic acid receptor specificity of erythrocytes affects haemagglutinin-inhibition test detection of antibody to avian haemagglutinin a single radial haemolysis assay for antibody to h haemagglutinin detection of anti-h responses in human sera by hi using horse erythrocytes following mf -adjuvanted influenza a/duck/singapore/ vaccine recombinant baculovirus influenza a haemagglutinin vaccines are well tolerated and immunogenic in healthy adults evaluation of recombinant haemagglutinin expressed in insect cells as an influenza vaccine in young and elderly adults baculovirus-derived haemagglutinin vaccines protect against lethal infection by avian h and h subtypes safety and immunogenicity of a recombinant hemagglutinin vaccine for h influenza in humans preparation of a standardized, efficacious agricultural h n vaccine by reverse genetics evaluation of a genetically modified reassortant h n influenza a virus vaccine candidate generated by plasmid-based reverse genetics cross-subtype protection in humans during sequential overlapping and/or concurrent epidemics caused by h n and h n influenza viruses influenza dna vaccines strategies for inducing protection against avian influenza a virus subtypes with dna vaccines impact of glycosylation on the immunogenicity of a dna based influenza h vaccine dna vaccine expressing conserved influenza virus proteins protective against h n challenge infection in mice heterotypic immunity against human influenza a viruses including recently emerged avian h and h viruses induced by iscom vaccine in mice requires both cytotoxic t-lymphocyte and macrophage function a randomized, double blind study in young healthy adults comparing cell mediated and humoral immune responses induced by influenza iscom vaccines and conventional vaccines mucosal delivery of inactivated influenza vaccine induces b cell dependent heterosubtypic crossprotection against lethal influenza a h n virus infection immunity to influenza a h n viruses induced by infection and vaccination generation and evaluation of a high-growth reassortant h n influenza a virus as a pandemic vaccine candidate safety and antigenicity of whole virus and subunit influenza a/hong kong/ / (h n ) vaccine in healthy adults: phase i randomised trial cold-adapted live influenza vaccine versus inactivated vaccine: systemic vaccine reactions, local and systemic antibody responses and vaccine efficacy: a meta-analysis genotypic stability of coldadapted influenza vaccine in an efficacy clinical trial recombinant influenza a virus vaccines for the pathogenic human a/hong kong/ (h n ) viruses comparison of the immune response to inactivated and live, attenuated influenza vaccines the efficacy of live attenuated cold adapted trivalent intranasal influenza virus vaccine in children intranasal immunization with formalin-inactivated virus vaccine induces a broad spectrum of heterosubtypic immunity against influenza a virus infection in mice influenza: vaccination and treatment searches of medline, pubmed, current contents, and references from relevant articles, as well as the extensive files of the authors identified data for this review. search terms were "avian influenza", "influenza vaccine'', "pandemic influenza", "h influenza", "h influenza", "h influenza", "influenza vaccines", "pathogenesis" and "virulence". english language articles were reviewed. key: cord- - p jk h authors: trampuz, andrej; prabhu, rajesh m.; smith, thomas f.; baddour, larry m. title: avian influenza: a new pandemic threat? date: - - journal: mayo clinic proceedings doi: . / . . sha: doc_id: cord_uid: p jk h in december , the largest outbreak of highly pathogenic avian influenza h n occurred among poultry in asian countries. a limited number of human h n infections have been reported from vietnam and thailand, with a mortality rate approaching %. deaths have occurred in otherwise healthy young individuals, which is reminiscent of the spanish influenza pandemic. the main presenting features were fever, pneumonitis, lymphopenia, and diarrhea. notably, sore throat, conjunctivitis, and coryza were absent. the h n strains are resistant to amantadine and rimantadine but are susceptible to neuraminidase inhibitors, which can be used for treatment and prophylaxis. the widespread epidemic of avian influenza in domestic birds increases the likelihood for mutational events and genetic reassortment. the threat of a future pandemic from avian influenza is real. adequate surveillance, development of vaccines, outbreak preparedness, and pandemic influenza planning are important. this article summarizes the current knowledge on avian influenza, including the virology, epidemiology, diagnosis, and management of this emerging disease. in december , the largest outbreak of highly pathogenic avian influenza h n occurred among poultry in asian countries. a limited number of human h n infections have been reported from vietnam and thailand, with a mortality rate approaching %. deaths have occurred in otherwise healthy young individuals, which is reminiscent of the spanish influenza pandemic. the main presenting features were fever, pneumonitis, lymphopenia, and diarrhea. notably, sore throat, conjunctivitis, and coryza were absent. the h n strains are resistant to amantadine and rimantadine but are susceptible to neu-raminidase inhibitors, which can be used for treatment and prophylaxis. the widespread epidemic of avian influenza in domestic birds increases the likelihood for mutational events and genetic reassortment. the threat of a future pandemic from avian influenza is real. adequate surveillance, development of vaccines, outbreak preparedness, and pandemic influenza planning are important. this article summarizes the current knowledge on avian influenza, including the virology, epidemiology, diagnosis, and management of this emerging disease. s ince mid-december , asian countries-cambodia, china, indonesia, japan, laos, south korea, thailand, and vietnam-have reported outbreaks of highly pathogenic avian influenza caused by the h n strain among poultry. this is the largest outbreak of avian influenza in poultry ever described. most of these countries experienced outbreaks of avian influenza for the first time. during the past months, more than million domestic poultry have died, or they have been culled to contain the epidemic and prevent the potential transmission to humans. despite the widespread infection of avian influenza viruses among poultry in asia, reported infection in humans has been rare to date. as of , only vietnam and thailand have reported influenza h n infection in humans. thirty-two human cases were laboratory confirmed, resulting in deaths, a mortality rate approaching %. however, most of the affected countries have limited capacity for surveillance of human disease. in addition, poultry production contributes substantially to the economies of the affected countries, resulting in considerable political pressure to minimize the extent and seriousness of the epidemic. therefore, the reported human cases of avian influenza may be underestimated. historically, this avian epidemic zoonosis is unprecedented in its scale, geographical distribution, economic losses, challenge for control, and potential public health consequences. the potential development of a human influenza pandemic similar to that of due to spanish influenza is a major concern. two of the key criteria that characterized the pandemic of - have already been fulfilled in the current epidemic: ( ) the ability of the virus to infect humans resulting in high mortality and ( ) a global immunologically naive human population. the third criterion, efficient human-to-human transmission, has thus far not been observed. the adaptation that would result in human-to-human transmission might involve changes in the receptor properties or improved viral replication efficiency. this adaptation might be achieved by mutation of an avian virus genome or by mixing segments of an avian virus with segments from a virus already adapted to humans (genetic reassortment), leading to the emergence of a new influenza subtype with pandemic potential. both events may occur easily. first, influenza viruses mutate frequently, potentially allowing them to change the host receptor specificity from avian to human. second, the segmented viral genome allows the exchange of genes between viruses if they infect the same host cell, which serves as the "mixing vessel." in the current h n outbreak in asia, no genetic reassortment among avian and human influenza viruses has been found; all genes are of avian origin. , however, the widespread epidemic of avian influenza in domestic birds increases the likelihood for mutational events and genetic reassortment. in view of the high mortality observed in the limited number of infections in humans, the prospect of a severe pandemic is of considerable importance. we review current knowledge about avian influenza, including the virology, epidemiology, diagnosis, and management of this emerging disease. for personal use. mass reproduce only with permission from mayo clinic proceedings. influenza viruses type a, b, and c belong to the family of orthomyxoviridae. these enveloped viruses contain a segmented single-stranded rna genome. a key difference among influenza virus types is their host range. type a viruses have been isolated from a wide range of species, including humans, pigs, horses, seals, ferrets, mink, whales, and birds. types b and c viruses infect humans predominantly but have also been isolated from seals and pigs, respectively. influenza a viruses can be divided into subtypes based on surface glycoproteins, hemagglutinin and neuraminidase. to date, different hemagglutinin (h -h ) and neuraminidase (n -n ) proteins have been identified. hemagglutinin facilitates entry of the virus into host cells through its attachment to sialic acid on epithelial cell receptors, promotes membrane fusion, and elicits protective neutralizing antibody response. hemagglutinin is the crucial component of influenza vaccines. neuraminidase has enzyme activity, which cleaves sialic acid on virion proteins, facilitating the release of progeny virions from infected cells. it is an important target for antiviral agents. although all influenza a virus subtypes have been found in birds, only different hemagglutinin (h , h , or h ) and different neuraminidase (n or n ) proteins have circulated widely in humans. the antigenic characteristics of influenza virus change gradually by accumulation of point mutations (antigenic drift) or profoundly by genetic reassortment (antigenic shift) in the genes encoding primarily hemagglutinin and neuraminidase. during antigenic drift, mutations occur because of the lack of the proofreading activity of viral rna polymerases. as a consequence, new antigenic variants emerge constantly, allowing the virus to evade immune recognition and giving rise to annual epidemics. the antigenic drift of influenza viruses requires the replacement of influenza strains used in the vaccine every several years. during antigenic shift, new strains appear to which most humans have no immunity and that have the potential to cause severe global outbreaks of human influenza. these pandemic strains derive from nonhuman viruses by interspecies transmission of the whole virus or by genetic reassortment between avian and human viruses that have infected a single cell. pigs have receptors for both avian and human influenza viruses and have been considered an intermediate host for the reassortment of influenza viruses. reemergence of a previously circulating virus to which most of the population is immunologically naive is another mechanism by which pandemic strains can occur. the nomenclature of influenza viruses includes the type of virus (a, b, or c), host of origin (excluding humans), geographical site of origin, strain number, and year of isolation, followed in parentheses by the antigenic description of the hemagglutinin and neuraminidase glycoproteins, eg, a/chicken/hong kong/ / (h n ). avian influenza viruses do not replicate efficiently in humans, which suggested initially that direct avian-to-human transmission would not occur. the hemagglutinins of avian strains bind preferentially to host receptors terminating in an α( , )-linked sialic acid, whereas human strains bind preferentially to receptors terminating in an α( , )linkage. the predominance of these receptors in different tissues partly reflects the tropism of influenza in different species. receptor specificity and inability of efficient replication in vivo were believed to provide a barrier against human infection by avian influenza virus. high doses of avian influenza virus strains were required for replication in volunteers. the first human infections by avian h n virus in hong kong in showed that receptor specificity was not a definitive host restriction factor. in this epidemic, an intermediate host was not necessary for transmission of avian strains to humans. all birds are thought to be susceptible to infection with avian influenza viruses. wild waterfowl and migrating bird populations provide an extensive natural reservoir for influenza a viruses ( figure ). the virus multiplies in the intestines of these birds, particularly in wild ducks, and they can carry the virus without developing signs of infection, indicating an optimal level of viral adaptation in these hosts. therefore, influenza is not an eradicable disease, and prevention and control of outbreaks are the only realistic goals. unlike mammalian influenza virus strains, avian viruses have shown little antigenic variability during the past decades. the high level of genetic conservation suggests that avian viruses have reached an evolutionary stage in which antigenic changes provide no selective advantage. infected birds excrete large amounts of virus in respiratory secretions, saliva, and feces. in the northern hemisphere, the prevalence of avian influenza peaks between late summer and early winter when the birds leave their breeding grounds and migrate; up to % of these birds may excrete virus. water sources that are contaminated by wild bird droppings and used by domestic poultry are a common and efficient means of viral spread. migratory birds are capable of flying long distances, and those migrating longitudinally appear to play a key role in viral transmission. figure . wild aquatic birds are the main reservoir for influenza a viruses, from which viruses can be transmitted to other hosts such as horses, pigs, poultry, whales, seals, and humans. as indicated by arrows, humans can also be infected by pigs and poultry. the fowl plague was first described in as a disease affecting chickens in italy. the causative agent was isolated from a chicken in , which was the first identified influenza virus (the human influenza virus was not identified until ). domestic poultry flocks are highly vulnerable to avian influenza, particularly birds that are raised outdoors. once introduced into domestic flocks, the virus can spread among farms via contaminated inanimate objects, contributing to the rapid evolution of epidemics. avian influenza in birds is characterized by a wide spectrum of symptoms, ranging from a mild illness to a highly contagious, severe, and rapidly fatal disease with a mortality rate approaching %. the latter syndrome was formerly known as fowl plague; it is now termed highly pathogenic avian influenza and is characterized by coughing, sneezing, excessive lacrimation, cyanosis of the unfeathered skin, edema of the head, ruffled feathers, diarrhea, nervous system disorders, or sudden death without clinical signs. in the past, most outbreaks of highly pathogenic avian influenza in poultry have been due to subtypes h or h . epidemics of avian influenza among poultry have produced serious economic consequences. in addition to a highly pathogenic avian influenza, viruses of low pathogenicity resulting in mild respiratory symptoms and reduced egg production can cause substantial economic losses. in , turkey farms in minnesota were affected by influenza virus h n , resulting in an economic loss of approximately $ million. moreover, avian influenza viruses of low pathogenicity can mutate into highly pathogenic viruses after circulating for several months. during the - epidemic in italy, the h n virus mutated within months to a highly pathogenic form, and more than million birds died or were culled. since , outbreaks of highly pathogenic avian influenza have increased in frequency and severity, and the number of novel strains suggests that the next influenza pandemic is imminent. in , outbreaks of highly pathogenic avian influenza occurred among chickens at farms in delaware, pennsylvania, texas, and maryland. the diseased and exposed birds were killed, and a quarantine zone was implemented around the affected farms. on february , , h n infection was confirmed in dead domestic cats and in a tiger in a zoo in thailand. to date, these animals have not been considered susceptible to influenza viruses. this raises concern about the need for surveillance in animals other than birds. since the late s, live poultry markets have been considered the source of human influenza viruses. these permanent live animal markets (wet markets) are embedded strongly in the food culture of asian countries. close human contact with live animals provides an ideal environment for the zoonotic transfer and evolution of infectious disease agents. the most important control measure for containing the outbreak in hong kong in was rapid destruction of the entire poultry population, proper disposal of carcasses, and rigorous disinfection of farms. to reduce the risk of reemergence of avian influenza, all aquatic birds were removed from retail markets, including ducks, geese, and quails (source of the h n strain). monthly "clean days" were introduced when all markets are emptied and cleaned simultaneously. new regulations mandate quarantine of poultry in designated farms in mainland china for days and testing for h infection before importation to hong kong. other control measures include continuous surveillance of influenza virus strains in humans and in birds, careful protection of cullers through appropriate personal protective equipment, restrictions on the movement of live poultry, and use of the human influenza vaccine to reduce the risk of coinfection in poultry workers and cullers. a global outbreak of influenza usually occurs when a new influenza virus emerges, spreads, and causes disease worldwide. descriptions of widespread and serious epidemics of respiratory disease suggestive of influenza have for personal use. mass reproduce only with permission from mayo clinic proceedings. *many people died within the first few days after infection, nearly half of whom were healthy young adults. †virus is still circulating. ‡illness occurred almost exclusively among persons younger than years. this pandemic did not increase mortality. no. of deaths been recorded for centuries. hippocrates in ancient greece described the first case of influenza-like illness. in the th century, human influenza pandemics emerged with intervals of to years (table ). the spanish influenza of - (h n ) was the most devastating pandemic in recorded human history, resulting in to million deaths worldwide; nearly half of those who died were healthy young adults. this figure is at least double the number of soldiers killed on the battlefields of europe during world war i. other less catastrophic pandemics occurred in (asian influenza), (hong kong influenza), and (russian influenza). the asian (h n ) and hong kong (h n ) pandemic strains were generated by reassortment between human and avian viral genes. the russian influenza virus (h n ) circulated in the s and reemerged in . the illness occurred almost exclusively among persons younger than years. the relatively low mortality rate associated with this pandemic can be attributed to the immunity of older individuals who had antibodies from their previous exposure to nearly identical viruses. to date, human infection with avian influenza viruses has been confirmed on several occasions ( table ). in , the first documented direct transmission of an avian influenza virus to humans occurred in hong kong, when an h n strain caused a severe respiratory disease in previously healthy young adults, of whom died. the outbreak in hong kong was controlled by the destruction of the entire poultry population; within days, more than . million chickens were killed. in , avian influenza h n viruses were isolated for the first time in humans; children were hospitalized with uncomplicated upper respiratory tract infection in hong kong, and both recovered completely. in may and in february and april , the poultry stocks in hong kong were again destroyed when the highly pathogenic h n virus reemerged in flocks. however, no more human cases of h n influenza were identified until february , when cases were confirmed in hong kong residents after travel to china, of whom died. in february , a large outbreak of h n avian influenza occurred in poultry farms in the netherlands. the virus caused mild illness in several farm workers, but a veterinarian who had visited an affected farm died of pneumonia. the virus isolated from the fatal case displayed amino acid substitutions, which possibly contributed to the increased disease severity. all farm workers received mandatory influenza vaccination and prophylaxis with oseltamivir. the h n poultry outbreak subsequently spread to germany and belgium but was eventually controlled by destruction of more than million domestic poultry. in february , another outbreak of h n avian influenza occurred on a poultry farm in british columbia, canada, and resulted in at least humans with infection, mainly conjunctivitis. recently, the crystal structure of the hemagglutinin from the virus was determined, explaining why this virus was able to spread efficiently in the human population despite retainment of the avian receptor-binding site. epidemiological studies suggest that most human h n infections resulted from contact with infected birds or surfaces contaminated with their excretions. however, evidence of limited human-to-human transmission of avian influenza viruses has occurred ( table ) . a case-control study of patients hospitalized for influenza virus h n disease in was conducted in hong kong. exposure to live poultry in the week before the onset of illness was significantly associated with h n disease, whereas traveling, eating, or preparing poultry products and recent exposure to persons with respiratory illness showed no significant association. in a cohort study including hospitals in hong kong at which patients infected with h n strains had been admitted, a significantly higher seropositivity rate for personal use. mass reproduce only with permission from mayo clinic proceedings. for h n was found among exposed health care workers ( . %) than among nonexposed ones ( . %), providing epidemiological evidence of transmission from infected patients to health care workers. in the netherlands in , family members of farm workers were infected during the h n outbreak, demonstrating the ability of human-to-human transmission. the present epidemic of highly pathogenic avian influenza virus in asia is historically unprecedented and extremely challenging. between december and in , sudden death occurred in , chickens at a farm near seoul, south korea; this was later confirmed as being caused by the highly pathogenic avian influenza virus h n . on january , , authorities in vietnam also reported several outbreaks of avian influenza h n at farms in the southern provinces. human cases of h n avian influenza presenting as severe respiratory illness occurred, with a mortality rate of more than %. on january , , the world health organization alerted the global outbreak alert and response network to support health authorities in the epidemiological investigation and containment of human cases. these h n viruses are substantially different from the h n viruses in outbreaks in hong kong in and , indicating that the virus has mutated. on january , , authorities in thailand reported an outbreak of highly pathogenic avian influenza among poultry, with laboratory-confirmed cases of h n infection in humans. japan, the european union, the united states, and other major export markets banned import of poultry products from the affected asian countries. preliminary clinical data from confirmed human cases of h n avian influenza from the current epidemic in vietnam were summarized recently. the mean age of the patients was . years (range, - years); none had any clinically important preexisting medical conditions. of the patients, had a history of direct contact with poultry (chicken or ducks), with a median time before onset of illness of days (range, - days). the main clinical features were fever, shortness of breath, cough, and diarrhea. notably, sore throat, coryza, and conjunctivitis were absent. all patients presented with pronounced lymphopenia (mean lymphocyte count, . × /l) and important chest radiographic abnormalities including diffuse, multifocal, or patchy infiltrates or segmental or lobular consolidation. eight of the patients ( %) died after a mean of days of illness. the clinical features, together with liver dysfunction, renal failure, coagulopathy, and pancytopenia seen in the hong kong h n outbreak, are similar to those seen in patients with severe acute respiratory syndrome. similarly, human infection with avian influenza h n reported in in hong kong presented as an influenzalike illness with pneumonia. reactive hemophagocytic syndrome was the most characteristic pathologic finding and probably contributed to the lymphopenia, liver dysfunction, and abnormal clotting profiles that were observed among these patients. gastrointestinal manifestations, renal failure unrelated to rhabdomyolysis, and pancytopenia were unusually prominent. factors associated with severe disease included older age, delay in hospitalization, lower respiratory tract involvement, and leukopenia or lymphopenia at admission. the preliminary findings suggest that cytokine dysfunction contributes to the severity of for personal use. mass reproduce only with permission from mayo clinic proceedings. testing is indicated for hospitalized patients with radiographically confirmed pneumonia, acute respiratory distress syndrome, or other severe respiratory illness for which an alternate diagnosis has not been established and history of travel to a country with documented h n avian influenza within days of symptom onset testing should be considered on a case-by-case basis in consultation with state and local health departments for hospitalized or ambulatory patients with temperature > °c (> . °f) and one or more of the following: cough, sore throat, shortness of breath and history of contact with domestic poultry (eg, visited a poultry farm, household raising poultry, or bird market) or a known or suspected human case of influenza h n in an h n -affected country within days of symptom onset h n disease. there is no evidence of h n virus replication outside the respiratory tract. viral replication seems to trigger a burst of cytokine production that may ultimately result in multiorgan failure. all patients who present to a health care setting with fever and respiratory symptoms should be questioned regarding their recent travel and exposure history. in patients at risk for avian influenza h n , laboratory testing is indicated ( table ). the optimal specimen for influenza virus detection is a nasopharyngeal aspirate obtained within days of the onset of symptoms; however, nasopharyngeal swabs and other specimens can be used. the h n influenza virus can be detected by rapid antigen tests, virus culture, and reverse transcriptase-polymerase chain reaction (rt-pcr). at least rapid antigen detection assays are commercially available and provide results in to minutes but are not as sensitive or specific as virus culture or rt-pcr. virus isolation in cell cultures enables further antigenic and genetic characterization, drug susceptibility testing, and vaccine preparation. however, cultures take to days and must be performed under biosafety level + laboratory conditions. conventional and real-time pcr assays detect diverse influenza type a viruses, including the avian h n strains. , polymerase chain reaction primers are directed to the conserved matrix gene of the virus, and therefore this assay would be expected to detect recombinant avian strains of the virus. of emphasis, avian influenza virus may be recombinant strains of the virus and may not contain the essential genes for replication in laboratory cultures. rapid antigen detection and rt-pcr can be performed with standard biosafety level laboratory conditions in a class ii biological safety cabinet. serologic diagnosis of influenza is based on the detection of a -fold or greater increase in specific antibody titer in paired serum samples; the first should be collected as soon as possible after onset of illness and the second, to days later. this limits the usefulness of serology in the diagnosis and treatment of acute illness. the current h n strains are resistant to amantadine and rimantadine but are susceptible to neuraminidase inhibitors (oseltamivir and zanamivir). these drugs are effective for prophylaxis and treatment of influenza a virus infection, including the avian influenza h n . however, no efficacy trials have been performed due to the small number of human cases. because a potential vaccine may be in short supply, antiviral drugs may play an important role in reducing the severity and spread of infection during the first stages of a pandemic. for prophylaxis, oseltamivir should be administered to individuals exposed to h n avian influenza within hours. therefore, a global influenza strategy in the st century calls for stockpiling antiviral drugs and drafting plans for rapid distribution. in geographic areas affected by avian influenza, individuals should avoid contact with poultry, and they should perform thorough and frequent hand hygiene using soap and water or alcohol-based hand rubs. the virus is killed by heat ( °c for hours, °c for minutes, or °c for minute) and common disinfectants such as alcohol, bleach, formalin, or iodine compounds. generally, % bleach solution is appropriate for dealing with biohazardous spillage. influenza virus can survive in feces for several months. it can survive in water for up to days at °c, for more than days at °c, and indefinitely in frozen material. therefore, poultry, including the eggs, should be cooked thoroughly. recently, the centers for disease control and prevention issued guidelines for airline flight crews and persons meeting passengers arriving from areas with avian influenza. protection of persons involved in outbreak eradication activities includes strict adherence to hand hygiene practices and the use of appropriate personal protective equipment (gloves, disposable clothing, shoe covers, safety goggles, and particulate respirators). during handling of human specimens, formation of aerosols and droplets should be minimized. isolation precautions identical to those recommended for severe acute respiratory syndrome should be implemented for all hospitalized patients diagnosed as having or being evaluated for avian influenza h n (table ). these precautions should be continued for days after for personal use. mass reproduce only with permission from mayo clinic proceedings. the current inactivated trivalent human influenza vaccine provides no protection against the h and h avian influenza strains. however, an important control measure is providing the seasonal human influenza vaccine to people at risk for avian influenza to reduce the risk of coinfection with avian and human influenza viruses simultaneously and to decrease the possibility of reassortment. the resultant hybrid virus could be highly transmissible among humans. a prototype virus and candidate vaccines have been developed for protection against the h n virus strain that infected people and resulted in death in hong kong in . however, the avian subtypes are rapidly lethal to chicken embryos, and therefore the traditional chicken embryo method is not applicable. alternative means of producing h and h vaccines were exploited, including the plasmid-based reverse genetic technology. a vaccine strain can be created by merging selected hemagglutinin and neuraminidase genes from the target virus with a laboratory virus. the resulting virus is recognized by the human immune system and causes a protective immune response but no disease. however, such vaccines have yet to be studied in clinical trials, and safety testing must be completed. the occurrence of avian influenza h n in humans is another reminder of our vulnerability to an emerging pandemic. several measures can help to minimize the global public health risk. an immediate priority is to halt further spread of epidemics in poultry populations that would reduce the opportunities for human exposure to the virus. clinicians should be cognizant of human influenza h n infection among patients with the appropriate epidemiological exposure, so that patients can be identified quickly and managed appropriately and health care workers can be protected. the reemergence of h n influenza in humans emphasizes the need to develop a vaccine against this virus. for personal use. mass reproduce only with permission from mayo clinic proceedings. available at: www.who.int/csr/disease/avian_influenza/en/. accessibility verified development of a vaccine effective against avian influenza h n infection in humans human influenza a h n virus related to a highly pathogenic avian influenza virus world health organization the pathogenesis of influenza in humans the structure and receptorbinding properties of the influenza hemagglutinin pandemic threat posed by avian influenza a viruses outbreaks of avian influenza a (h n ) in asia and interim recommendations for evaluation and reporting of suspected cases-united states are we ready for pandemic influenza? influenza virus neuraminidase inhibitors realities and enigmas of human viral influenza: pathogenesis, epidemiology and control pandemic influenza: its origin and control influenza type a in humans, mammals and birds: determinants of virus virulence, host-range and interspecies transmission animal influenza virus surveillance influenza: an emerging disease wet markets-a continuing source of severe acute respiratory syndrome and influenza? outbreak of avian influenza a(h n ) virus infection in hong kong in human infection with influenza h n avian influenza a virus (h n ) associated with human conjunctivitis and a fatal case of acute respiratory distress syndrome transmission of h n avian influenza a virus to human beings during a large outbreak in commercial poultry farms in the netherlands case-control study of risk factors for avian influenza a (h n ) disease, hong kong risk of influenza a (h n ) infection among poultry workers, hong kong, - cases of influenza a (h n )-thailand world health organization international avian influenza investigative team. avian influenza a (h n ) in patients in vietnam clinical features and rapid viral diagnosis of human disease associated with avian influenza a h n virus pathology of fatal human infection associated with avian influenza a h n virus detection of influenza a viruses from different species by pcr amplification of conserved sequences in the matrix gene multiplex real-time pcr assay for detection of influenza and human respiratory syncytial viruses available at: www.cdc.gov/flu/avian/index.htm. accessibility verified sars: epidemiology, clinical presentation, management, and infection control measures prevention and control of influenza: recommendations of the advisory committee on immunization practices (acip) a. strict hand hygiene before and after all patient contact b. use of gloves and gown for all patient contact c. use of eye protection when within feet ( m) of the patient d. use of shoe covers when entering the isolation room e. placement of the patient in an airborne isolation room key: cord- - ocseuz authors: donnelly, christl a; ghani, azra c; leung, gabriel m; hedley, anthony j; fraser, christophe; riley, steven; abu-raddad, laith j; ho, lai-ming; thach, thuan-quoc; chau, patsy; chan, king-pan; lam, tai-hing; tse, lai-yin; tsang, thomas; liu, shao-haei; kong, james hb; lau, edith mc; ferguson, neil m; anderson, roy m title: epidemiological determinants of spread of causal agent of severe acute respiratory syndrome in hong kong date: - - journal: lancet doi: . /s - ( ) - sha: doc_id: cord_uid: ocseuz background: health authorities worldwide, especially in the asia pacific region, are seeking effective public-health interventions in the continuing epidemic of severe acute respiratory syndrome (sars). we assessed the epidemiology of sars in hong kong. methods: we included cases reported up to april , . an integrated database was constructed from several sources containing information on epidemiological, demographic, and clinical variables. we estimated the key epidemiological distributions: infection to onset, onset to admission, admission to death, and admission to discharge. we measured associations between the estimated case fatality rate and patients’age and the time from onset to admission. findings: after the initial phase of exponential growth, the rate of confirmed cases fell to less than per day by april . public-health interventions included encouragement to report to hospital rapidly after the onset of clinical symptoms, contact tracing for confirmed and suspected cases, and quarantining, monitoring, and restricting the travel of contacts. the mean incubation period of the disease is estimated to be . days ( % cl . – . ). the mean time from onset of clinical symptoms to admission to hospital varied between and days, with longer times earlier in the epidemic. the estimated case fatality rate was . % ( . – . ) for patients younger than years and . % ( . – . ) for patients aged years or older assuming a parametric γ distribution. a non-parametric method yielded estimates of . % ( . – . ) and . % ( . – . ), respectively. case clusters have played an important part in the course of the epidemic. interpretation: patients’age was strongly associated with outcome. the time between onset of symptoms and admission to hospital did not alter outcome, but shorter intervals will be important to the wider population by restricting the infectious period before patients are placed in quarantine. published online may , http://image.thelancet.com/extras/ art web.pdf background health authorities worldwide, especially in the asia pacific region, are seeking effective public-health interventions in the continuing epidemic of severe acute respiratory syndrome (sars). we assessed the epidemiology of sars in hong kong. methods we included cases reported up to april , . an integrated database was constructed from several sources containing information on epidemiological, demographic, and clinical variables. we estimated the key epidemiological distributions: infection to onset, onset to admission, admission to death, and admission to discharge. we measured associations between the estimated case fatality rate and patients' age and the time from onset to admission. findings after the initial phase of exponential growth, the rate of confirmed cases fell to less than per day by april . public-health interventions included encouragement to report to hospital rapidly after the onset of clinical symptoms, contact tracing for confirmed and suspected cases, and quarantining, monitoring, and restricting the travel of contacts. the mean incubation period of the disease is estimated to be · days ( % ci · - · ). the mean time from onset of clinical symptoms to admission to hospital varied between and days, with longer times earlier in the epidemic. the estimated case fatality rate was · % ( · - · ) for patients younger than years and · % ( · - · ) for patients aged years or older assuming a parametric ␥ distribution. a non-parametric method yielded estimates of · % ( · - · ) and · % ( · - · ), respectively. case clusters have played an important part in the course of the epidemic. the rapid worldwide spread of the coronavirus that causes severe acute respiratory syndrome (sars) , has led to countries reporting cases as of may , . the evolution, spread, and persistence of infectious diseases are facilitated by the mobility of contemporary society, for example through air travel, the continued growth in the world population, and the steady rise in the number of densely populated urban areas, especially in asia. the asia pacific region, including mainland china, has been badly affected by sars. the impact on the regional economy and health-care systems led to a meeting of health ministers from association of south east asian nations on april - . health authorities are urgently seeking guidance on the public-health measures most likely to be effective in controlling the epidemic. key epidemiological determinants of the magnitude and timescale of the epidemic (figure ) include the interval between infection and onset of symptoms and between onset and hospital admission, the degree and duration of the infectiousness of the agent, and the extent of contact and mixing between infectious and susceptible people enabling transmission of the virus. public-health interventions can affect many of these factors. the hong kong authorities have taken several measures to combat the spread of sars. since formal recognition of the outbreak in the prince of wales hospital, hong kong, on march , these measures have included: public-service announcements about personal protection (march ); addition of sars to the list of notifiable diseases and requests for close contacts of cases to attend designated medical centres for screening (march ) until the later introduction of mandatory home quarantine; a -week suspension of schools' (march ) and universities' (march ) sessions; introduction of health declarations for all incoming residents and visitors (march ); isolation of residents of a building in the amoy gardens estate, at the centre of a cluster of about cases (march ) and their subsequent move to rural isolation camps for days (march ); home quarantining of close contacts and restrictions on their travel out of hong kong (april ); new public announcements urging symptomatic people to seek medical attention (april ); and bodytemperature checks for all air passengers (april ). in the global response to sars, there are three priority tasks: the identification of the causal agent and the development of tests to detect the virus and allow rapid confirmation of cases; the development and assessment of treatment protocols; and the determination of the key epidemiological processes and parameters that affect the spread and persistence of infection to support the formulation of appropriate public-health interventions. we describe the epidemiology in hong kong in the first weeks of the epidemic, during which cases were confirmed, and deaths from sars occurred. we focus on the key distributions and parameters that define the observed pattern of the spread of sars, and their change over time since the introduction of the virus into hong kong. we analysed an integrated database, coordinated by the department of community medicine, university of hong kong on behalf of the health, welfare and food bureau, derived from the hong kong hospital authority esars system, and the department of health's master list, which contains details of all patients with confirmed or suspected sars admitted to hospitals in hong kong since feb , . primary health care in hong kong is provided by private practitioners ( %) and general outpatient departments operated by the public sector. the hospital authority also currently provides % of total inpatient bed-days. the department of health provides the public-health function, including the monitoring and control of communicable diseases. the esars system is designed as a registry and monitoring system. all patients admitted for investigation and observation into the sars cohort wards in all the hospitals under the hospital authority of hong kong are recruited on entry. the patients on the registry are progressively classified into: patient under observation, patient suspected of sars, patient with confirmed sars, and not sars. the criteria for inclusion in the esars register as a patient confirmed with sars are radiographic evidence of infiltrates consistent with pneumonia, and current fever higher than ºc or history of such at any time in the past days, and at least two of the following: history of chills in the past days, cough (new or increased) or breathing difficulty, general malaise or myalgia, and known exposure. patients are listed as suspected of having sars if they do not fulfil this definition but are still thought to be likely cases of sars on the basis of the collective evidence and clinical judgment. however, patients are excluded if an alternative diagnosis can fully explain their illness. a questionnaire was administered to all patients h after confirmation of sars by the department of health, initially by regional community-medicine teams and later by a central interviewing team of nurses, to record symptoms at presentation to hospital and to identify contacts and events of probable relevance to transmission. when possible, patients are classified into infection clusters by location (eg, housing estates), occupation (eg, health-care workers), and workplace (eg, hospitals and other buildings). in addition, we used demographic data on hong kong, which has a population size of · million in districts (figure ). time-delay distributions (infection to onset, onset to admission, admission to death, and admission to discharge) were fitted to ␥ distributions by maximum likelihood estimation methods, with allowance for censoring for incomplete observation of the disease process in all cases. likelihood ratio statistics were used for tests of significance when comparing distributional parameters and for calculating ci. while the epidemic is continuing, the estimation of the admission-to-death and admission-to-discharge distributions must be undertaken jointly with the estimation of the case fatality rate, because among patients still recorded as being in hospital it is impossible to ascertain who will eventually die or be discharged. we assume that no confirmed sars patients who has been discharged from hospital will go on to die of sars-related causes. if f() and g() are the cumulative distribution functions of the admission-to-death and admission-todischarge distributions, respectively, and f is the case fatality rate-ie, the proportion of sars patients who will die of the disease-the following likelihood structure is assumed: if a patient died t days after admission, the likelihood is f ϫ[f(t+ )-f(t)]; if a patient was discharged t days after admission, the likelihood is ; and if a patient remained in hospital t days after admission, the likelihood is . the parameters of the f() and g() distributions are thus jointly estimated along with the case fatality rate. to assess further the case fatality rate, we also used a version of the kaplan-meier survival curve, adapted to allow for two types of outcome (death and discharge). censoring was used to obtain non-parametric estimates of the admission-to-death and admission-to-discharge distributions and the case fatality rate. the sponsors of the study had no role in the study design, data collection, data analysis, data interpretation, or in the writing of the report. the development of the epidemic (figure ) features a period of exponential growth, beginning on march , after the formal announcement of the outbreak, followed by a period of comparative stability throughout early to mid april, with evidence of a slight decay over the week april - . the geographical and age distributions of the cases are presented in figure . % of patients were female and % male. clinical symptoms at presentation were fully recorded for about % of the cases confirmed by the department of health. the frequency of self-reported symptoms is similar to that noted in the early cases. the most common reported symptom was fever ( %), with - % of patients reporting general influenza-like symptoms, chills, malaise, loss of appetite, and myalgia. gastrointestinal symptoms were less common at presentation, including diarrhoea ( %), vomiting ( %), and abdominal pain ( %). % reported fever plus any one other symptom, and % fever plus one of the five most common symptoms (table) . infection events cannot be observed, but for patients with short and defined periods of exposure to known sars cases, data on the timing and duration of exposure can be used to estimate the distribution of the incubation period, the time from infection to the onset of clinical symptoms of sars. the database contained patients with one exposure to sars over a limited time scale with recorded start and end dates. the maximum likelihood estimate of the mean and variance of the time from infection to onset was · days ( ci · - · ) and · days , respectively; therefore % of patients would experience the onset of symptoms within · days of infection. the estimated distribution is presented in figure . however, this distribution is based on a limited number of observations to date, and has high variance and may reflect biases in reporting, different routes of transmission, or varying infectious doses of the virus. onset and admission times are both observable events. however, allowance must be made in the analysis for censoring due to incomplete observation. if censoring is not taken into account, the distribution will be biased towards short onset-to-admission times, because patients are only eligible to be included in the hospital-based database on admission to hospital. patients with recent onsets and long onset-to-admission times are less likely to have been admitted to hospital and thus be included. in the analysis, patients were grouped by their week of clinical onset, and seven weekly time periods were analysed (feb to march , march - , march - , march - , march to april , april - , and april - ). there were too few patients with clinical onset before feb for robust analysis and too little time has elapsed after onset to allow analysis of those with clinical onset after april . we assume that the recorded data are complete up to april . estimated mean onset-toadmission times were obtained for each week, assuming that the times were ␥ distributed: feb to march the estimated mean and variance of the admission-todeath time was · days and · days, respectively, and the estimated mean and variance of the time from admission to discharge was · days and · days, respectively (figure ). if ␥ distribution is assumed, the estimated distributions and case fatality rate varied as a function of patients' age, but not the time from onset to admission (figure ). the estimated case fatality rate for patients younger than years was · % ( · - · ) and · % ( · - · ) for patients aged years and older. the adapted kaplan-meier-like nonparametric method gave estimates of · % ( · - · ) and · % ( · - · ), respectively (figure ). the estimated fatality rates are higher than the estimate obtained from the current cumulative number of deaths divided by the current cumulative number of hospital admissions, because of the incomplete follow-up on patients still in hospital. a key feature of this epidemic is the clustering of cases in place and time linked to a particular individual (in some cases in a particular setting such as a residence block or health-care setting), where one primary case has led to many secondary and tertiary cases. the amoy gardens outbreak is particularly striking, with the onset times of the cases identified as arising from this setting following a ␥ distribution (figure ). work on the clusters is still evolving and will be reported in detail separately. our findings underline the importance of estimating the key epidemiological determinants of the epidemic, the infection-to-onset and onset-to-admission interval distributions. the analysis of the onset-to-admission interval shows that over time there has been a progressive shortening of the time from clinical onset of symptoms to presentation at hospital. the estimation of case fatality rates in the situation of an emerging epidemic is not straightforward. first, our estimates are derived from data on clinical cases that have been admitted to hospital and, hence, estimate the mortality rate only in this population. second, the temporal evolution of the epidemic complicates analysis. finally, the estimates of the case fatality may vary dependent on the methods used and their underlying assumptions, although the estimates we present have statistical validity. all these issues require further investigation as the epidemic evolves, and explain partly the wide range of mortality estimates reported to date. shortening the time between onset of clinical symptoms and admission to hospital does not seem to affect clinical outcome. however, shortening the time from clinical onset to admission expedites isolation and reduces the effective infectious period and, thus, the risk of onward transmission. such changes were already evident in late march and early april, but any additional shortening of the time that symptomatic individuals are in the community will lead to further benefits at the population level. the extent to which this time needs to be shortened to reduce the generation of secondary cases from each primary case to less than one (the effective reproductive number, r ) in hong kong is the subject of a continuing analysis. given the likely benefits to the wider community from early presentation at hospital after the onset of symptoms, there should now be an intensive assessment of the different public-health interventions, including publicity campaigns in various media, to assess their impact on the early reporting of symptoms. the promotion of early reporting of all symptoms will challenge the health-care system in dealing with those caused by other pathogens and the so-called worried well. however, given the high need for intensive care of patients, the case fatality rate, and public alarm worldwide, use of stringent measures to limit the effective infectious period of probable sars cases would seem prudent. this approach alone may contribute substantially to the eventual curtailing or even eradication of the epidemic. the epidemic has shown the need for communication of risk that will inform and warn the public, in a way that will improve personal protection, without inducing raised anxiety and fear, as an essential part of epidemic control. a change in risk perception would potentially lead to an increase in early reporting of symptoms as well as improvements in hygiene and prevention of transmission. further data may reveal that the incubation period depends on the route of transmission and on the infectious dose received by an individual. the duration of the infectious period and its relation to the incubation period is uncertain at present (for example, the onset of infectiousness may precede the onset of clinical symptoms). continuing clinical studies involving quantitative assays of viral load at known times after exposure and after the onset of clinical symptoms should, however, clarify this property of the sars agent. critical questions relating to how long patients should remain in isolation are whether and to what extent virus remains in faeces or in aspirate after overt clinical symptoms have stopped. the occurrence of clusters of cases linked to particular individuals in a particular spatial setting has been an important determinant of the overall magnitude of the epidemic to date. a who team has now joined the hong kong government in examining on-site factors that were apparently associated with a possible point-source outbreak in amoy gardens. the assessment of whether there is variation in the characteristics of the disease, including presenting symptoms by different clusters, requires further investigation as the definition of clusters improves. the occurrence of clusters is not necessarily a feature that can inform public-health interventions in advance, except within health-care settings in which stringent isolation procedures must be adopted in handling suspected and confirmed cases. clusters do, however, provide a focus for contact-tracing studies to assess incubation periods and the nature of the contact that resulted in transmission. the reported cases to date in hong kong and elsewhere may simply reflect people with the most severe clinical symptoms of infection with the new sars virus. we estimated the case fatality rate based on cases in hospital only. if additional infections in the community do not lead to admission to hospital or death, the case fatality rate based on all infections would be lower. community-based serological surveys to assess infection and recovery rates are a priority once a specific and sensitive serological test is available. finally the warm season has begun in hong kong, with daily temperatures now at - ºc. the seasonal risks of figure : non-parametric and maximum-likelihood ␥ probabilities of survival and discharge dengue and influenza will increase, and if serious outbreaks occur, they will complicate the triage of patients with possible symptoms of sars. thus, measures that can be taken now to limit further transmission, such as the shortening of the onset-to-admission interval, should be given high priority. we thank david r cox for developing a suitable non-parametric method for estimation of the case fatality rate. acg and nmf receive fellowship support from the royal society. sr and nmf receive research funding from the howard hughes medical institute, cf, lja-r, and nmf from the medical research council, and rma from the wellcome trust. we thank tom johnston for geographic information system assistance. we thank all our colleagues in the department of health and the hospital authority for their work in data collection and processing, and pay tribute to all the front-line health workers who are caring for patients with sars. coronavirus as a possible cause of severe acute respiratory syndrome coronavirus never before seen in humans is the cause of sars department of health, hong kong government of special administrative region website a cluster of cases of severe acute respiratory syndrome in hong kong cumulative number of reported probable cases of severe acute respiratory syndrome (sars) academic medical center, department of neurosurgery, az amsterdam, netherlands (h van santbrink, p c de witt hamer) a -year old man was admitted after neckpain of sudden onset evolving to intractable headache in minutes. on physical examination he was alert and had no focal neurological deficit. severe meningism caused noticeable opisthotonic fixation of the neck. computed tomography (ct) of the cerebrum suggested subarachnoidal haemorrhage with subtle blood in the perimesencephalic cisterns, beneath the tentorium, and in the fourth ventricle. routine ct angiography, digital subtraction angiography of the four cerebral vessels, and magnetic resonance imaging (mri) of the craniocervical junction did not show a bleeding focus. the combination of persistent opisthotonus and radiological subarachnoidal haemorrhage strongly suggested a bleeding source, and motivated further investigation. mri of the neuraxis revealed an arteriovenous malformation of the medullary cone dorsal from vertebral corpus l (figure). the current finding extends the routine diagnostics for intracranial subarachnoidal haemorrhage without focus to mri of the entire neuraxis. endovascular treatment of the malformation is considered for this patient.clinical picture key: cord- -t v zt authors: lee, p.; lam, p.t.i.; yik, f.w.h.; chan, e.h.w. title: probabilistic risk assessment of the energy saving shortfall in energy performance contracting projects–a case study date: - - journal: energy build doi: . /j.enbuild. . . sha: doc_id: cord_uid: t v zt lack of a proper assessment method on performance risks in energy performance contracting (epc) projects is one of the reasons hindering the further development of energy service companies (escos) market. this paper proposes a simulation-based method to evaluate the probability of energy saving shortfall taking into account the variations in the influential parameters, including weather conditions, occupancy, operating hours, thermostat set-point, etc., during the contract period. the proposed method involves the use of a detailed building energy simulation programme, sensitivity analysis and monte carlo simulation techniques. empirical data is also used to develop the probability distribution functions for the identified parameters to simulate the actual yearly variations in the post-retrofit conditions. a real case study of replacement of heat rejection system for a central chiller plant in hong kong is used to demonstrate the application of this probabilistic method. the result shows that the possible energy savings after a -year retrofit period ranges from , kw h ( . %) to , kw h ( . %) with % statistical significance. buildings account for % of the world's energy use, and most of the existing buildings are not so energy efficient as modern technology allows [ , ] . as such, energy retrofitting of existing building services equipment can yield significant amount of energy savings. however, the lack of upfront capital and technological know-how are usually hurdles to undertaking energy improvement projects although the benefits of such works, for example, a substantial reduction in utility costs and improvement of the built environment, are obvious. energy performance contracting (epc) is recognised as a means to tackle this problem in many countries, including the united states, australia, germany, japan, singapore and china [ , ] . the european parliament defines epc in the directive / /ec as "a contractual arrangement between the beneficiary and the provider (normally an esco) of an energy efficiency improvement measure, where investments in that measure are paid for in relation to a contractually agreed level of energy efficiency improvement." [ ] . it means that, under an epc arrangement, energy service companies (escos) guarantee or share the energy savings with building owners. building owners only make a series of payment to escos when the actual energy savings are materialised. in the case of shortfall in savings, escos will compensate the loss incurred by building owners. to ensure the guaranteed energy saving can be achieved, a proper assessment method on the probability of energy saving shortfall is needed to evaluate such project risks. mills et al. [ ] identified the risks associated with energyefficiency projects and classified them into five aspects, namely economic, contextual, technology, operation, and measurement and verification (m&v) risks. several risk management approaches (e.g. financial hedging, careful design, proper metering, etc.) were also introduced to mitigate the associated risks in their study. however, even though escos can better manage the performance risks by ensuring system efficiency, optimisation control and better maintenance, the actual energy saving is still uncertain. this is attributed to various extrinsic factors including weather conditions, economic circumstances, as well as occupants' behaviour, which can significantly affect the actual energy savings. for example, the occupancy rate of hotel may decrease dramatically due to economic downturn, resulting in a significant reduction in the actual energy savings. therefore, a dilemma is often observed from the escos' perspective in determining the amount of guaranteed energy savings. on one hand, escos try to mitigate the performance risks by being conservative on the guaranteed savings, but on the other hand, to increase chances of winning bids by offering higher energy saving guarantee and shorter contract period. several attempts were made to develop such an assessment method. rickard et al. [ ] adopted the technique of coefficient of . collect building & system info rmat ion , utilit y bills and measured data. . develop and ca librate two energ y model s usi ng utilit y bills and measured data. developmen t of pre -an d post -retrofit models . identif y inf lue ntial par ameters af fecting ener gy us e. . select the ran ge and in terval fo r sensitivit y analysi s. . calculate and rank the influential coeff icient for the influential pa rameters. . analyse the non -linearity situation and discard the non-inf luential pa rameters. developmen t of probability di stribution for the sel ected par ameters . collect the empirical data from st atistical data and previous research. . determine the repres entative p robabilit y distribution functions using curve fi tting techniqu es. simulation of possi ble energy saving analysis an d discussio n of simulation resul ts . generate a common set of post -retro fit period data using latin hypercube s ampl ing. . modify and reproduce the w eather fi les ba sed on the sampling resul ts. . incorporate c ommon data set into the calib rat ed energy mode ls. . run the simulat ions fo r each case of common data set. variation (cv) to compare saving uncertainties in different energy efficiency measures. however, some drawbacks were found in this technique, for example, several simplified assumptions had to be made for project comparison and a number of risk factors were excluded in the analysis. mathew et al. [ ] indicated the possible use of actuarial pricing approach to quantify the associated risks for project decision-making. however, this approach requires a large number of actual epc project data, but the non-standardised project information and poor data quality often hinder the development of a reliable actuarial database [ ] . mills et al. [ ] and jackson [ ] suggested using the monte carlo technique for quantifying the risks related to epc projects, but their studies only focused on the illustration of a proposed methodology and no real project data is used to demonstrate the credibility of their findings. this paper aims at developing a simulation-based method to evaluate the probability of energy saving shortfall taking into account the variations in the influential parameters. it is structured as follows. first, the probabilistic method is presented to quantify performance risks for energy saving shortfall under guaranteed epc projects. the method involves the use of a detailed building energy simulation programme, sensitivity analysis and the monte carlo simulation techniques. second, a case study of replacement of heat rejection system for a central chiller plant in hong kong is used for illustrating the application of this probabilistic method. finally, the results of this case study are presented. fig. shows the procedure and methods used for quantifying the probability of energy saving shortfall in guaranteed epc projects. the whole procedure consists of four main steps. i development of pre-and post-retrofit models: the first step is to develop two energy models that can predict representative energy consumption of the building at the pre-and post-retrofit stages. with the two models, the actual energy savings can be predicted taking into account any deviation in the post-retrofit conditions from the baseline conditions. the models should be developed by using a detailed building energy simulation programme, which allows users to input all essential building information, system & equipment specifications, as well as operational characteristics for realistic energy use predictions. the two models should be basically identical except the retrofitted systems and the conditions with significant changes (e.g. change of occupancy). to ensure the representativeness of the models, the models should be calibrated with the measured energy use data. details of the calibration procedures can be referred to other published literature and guidelines [ ] [ ] [ ] [ ] . ii sensitivity analysis: the second step is to identify the importance of influential parameters affecting energy use. in general, the influential parameters can be summarised into three categories, namely "building load", "system control and operation" and "equipment, system and plant". for the selection of influential parameters, attention should be paid to those parameters that are likely to change during the epc contract period, for example, weather conditions, occupancy rate, operating hours, etc. some of the influential parameters may be excluded, for example, building height, materials used in building facade, orientation, etc., since these parameters are unlikely to change during the contract period. in some projects, an exclusion clause is incorporated to protest the interest of escos and hosts in case of significant changes in the baseline conditions (e.g. large scale renovation works are conducted during the contract period). those parameters can also be discarded in the sensitivity analysis. there are three common techniques to conduct sensitivity analysis, namely differential sensitivity analysis (dsa), random sensitivity analysis (rsa) and stochastic sensitivity analysis (ssa) in the field of building energy study [ , ] . in comparison with these techniques, differential analysis by finite differences (fd) is most widely used because the calculations are easy and there are fewer problems to incorporate into the simulation programme. this technique has been widely used by researchers to determine the most sensitive parameters affecting building energy use [ ] [ ] [ ] [ ] [ ] . the selection of a proper range and interval is essential to obtain accurate results in sensitivity analysis. therefore, the range and intervals selected should cover the two extreme scenarios with a reasonably narrow interval. nonlinearity issues should also be studied when the standard deviation of the influence coefficient (ic) is large. the procedure of performing differential sensitivity analysis is presented in the later part of this paper. iii development of probability distribution for selected parameters: the third step is to develop the probabilistic distribution function (pdf) for each of the selected parameters. the selection of the representative pdf is critical in this analysis as it is used to simulate the yearly variations in those selected parameters during the post-retrofit period. empirical data from official database and previous research are used to determine the corresponding pdf for the selected parameters using curve-fitting techniques. three goodness-of-fit tests, namely the chi-square test, the kolmogorov-smirnov (k-s) test, and the anderson-darling (a-d) test, are performed to evaluate how well the assumed distributions fit a set of sample data [ ] . the chi-square test is used to determine the validity of two or more theoretical distribution models. the k-s test serves the same purpose, but with fewer limitations in application such as a large number of intervals. the a-d test is particularly useful when the tails of a distribution reflect an essential distribution characteristic. the lower the goodness-of-fit value of these tests is, the more representative the assumed pdf is selected. for those parameters without empirical data to determine, a triangular distribution is proposed to be the representative pdf, and the most likely value should be regarded as the baseline condition. iv simulation of possible energy saving: the fourth step is to simulate energy saving taking into account all possible combinations of selected parameters during the post-retrofit period. monte carlo simulation is performed to generate a common set of post-retrofit condition data based on the pdf of the selected parameters. monte carlo simulation is a mathematical method where output values are randomly generated based on the assumed distributions of the independent parameters. a smooth approximation of the output distribution is obtained with large sample sizes (e.g. by iterating , simulation runs). this technique has been applied in a number of probabilistic analysis [ ] [ ] [ ] [ ] [ ] .the latin hypercube sampling method is proposed to generate those random numbers, because it more precisely reflects the shape of a defined distribution with relative small sample sizes [ ] . detailed building energy simulation programmes usually require the weather and input data files to run the simulation. to simulate the energy saving uncertainty associated with yearly weather variations, it is necessary to modify and reproduce the typical weather file , times in accordance with the results of each monte carlo simulation. the algorithm of weather adjustment for the original weather file is based on a "morphing" method, developed by belcher et al. [ ] who constructed design weather data for future climates. chan [ ] also adopted this morphing method to modify the hong kong typical meteorological year (tmy) weather file taking into accounts the effect of urban heat islands. the procedure of this method will be illustrated in the later part of this paper. similarly, , input files are required to generate based on the result of monte carlo simulation. each weather and input file represents one of the possible yearly conditions during the post-retrofit period. these weather and input files are run on the detailed energy building simulation programme for the pre-and post-retrofit models to simulate possible range of energy savings. the above method for quantifying the probability of energy saving shortfall is illustrated through a real epc project in the composite buildings. this development consists of three commercial towers with a total gross floor area (gfa) of around , m , which were built in the late s. the first two towers, denoted as a and b, are symmetrical in building shape, and each comprises serviced apartment (sa) storeys and office storeys. the remaining tower, denoted as c, is solely for storeys of office premises. similar to other typical high-rise buildings below storeys [ ] , a reinforced concrete structure was adopted and the building facades are made up of curtain walls while the windowto-wall ratio (wwr) is around . for four orientations. reflective double glazing glasses are used for all towers. table shows the design parameters of these towers. a central chiller plant system is used to provide cooling to these towers. this chiller plant system comprises units of the day-mode ton chiller and units of the night-mode ton chiller. the primary-secondary pumping system is adopted and the seawater cooling system was used for heat rejection. the three day-mode chillers operating from : to : are capable of providing air the gross floor area of a building means the area contained within the external walls of the building measured at each floor level (including any floor below the level of the ground), including the thickness of the external walls of the building. the building authority may disregard essential building services areas from gross floor area calculation. (cap -building planning regulations for hong kong sar). conditioning for both the office and sa premises. for the remaining time, the ac operation is switched from the day-mode to the night mode, and only the sa premises are provided with air conditioning service. an energy audit was conducted by the esco after years operation of the building. a design problem was found in the seawater cooling system in that the central chilled water plant was supplied with seawater, which was discharged from an adjacent central chiller plant for chiller condenser cooling, after the seawater had been used to cool the chillers in the adjacent plant. as the "indirect" seawater supply was at much higher temperatures than the original design level, the chiller plant had been running at rather low coefficient of performance (cop). the poor quality of the seawater also exacerbated corrosion of condenser tubes, causing further lowering of the cop. in order to address these problems, the esco and host agreed that the existing seawater cooling system should be replaced with a fresh-water evaporative cooling tower system, and the project was implemented under an epc guaranteed saving package. the actual energy saving was calculated based on the common set of post-retrofit period conditions per annum. the isolation approach [ ] was adopted to measure the annual energy consumption of the whole chiller plant, including chillers, chilled water pumps and seawater pumps. other energy and cost-avoided savings (e.g. reduction in maximum demand use and maintenance costs) were not considered in this study. table shows the component of chiller plant equipment for energy saving calculation in this retrofit project. two building energy models, representing the energy consumption at the pre-and post-retrofit stages, were developed using energyplus [ ] . energyplus is a detailed building energy simulation program developed by the department of energy (doe) in the united states. this program has been tested and validated according to ashrae standard [ ] and a number of researchers have utilised energyplus to carry out sensitivity and parametric analysis for building energy use [ , ] . the composite buildings consist of two types of premises: office and serviced apartment, on a total of usable floors. for simplicity, a model for only three typical floors was developed to represent the whole composite buildings. as tower a and tower b are symmetrical to each other in shape, the first typical floor model, denoted as ty , represents the sa premises of towers a and b. similarly, the second typical floor model, denoted as ty , represents the office premises of towers a and b. the third typical floor model, denoted as ty , represents the office premises of the whole tower c. no roof and ground floors were modelled, because the top floors of all the three towers are used to house lift machine rooms, potable water, flush water and fire services water tank while the towers are atop a basement floor. therefore, it would be reasonable to assume that heat transfers to the air-conditioned area caused by direct solar heat gain and ground temperature variations would be limited. to ensure that the operating conditions of the chiller plant in the pre-retrofit period could be realistically modelled, a complete year of monthly energy use data of the chiller plant was collected and used as the basis for comparison while the operating conditions were tuned. a spot measurement was also conducted to evaluate the overall cop of the chiller plant. the other baseline conditions, including the occupancy rate of the office and sa premises, were obtained from relevant documentary records. table shows the energyplus input details. the pre-retrofit model was calibrated with reference to equipment nameplate data, operating schedules, occupancy patterns, etc. for those missing data which were required as inputs to energyplus, estimates were made based on common practices and regulatory requirements, such as the building energy code [ ] . the simulated results were compared to the monthly electricity bills data. the calibration procedures and requirements were in accordance with the ashrae guideline [ ] . the post-retrofit model was developed based on the pre-retrofit model except the retrofitted part. similarly, one complete year of post-retrofit data was collected for calibration of the post-retrofit model. other data and information, including new occupancy rate, operating schedules, as well as plant performance after retrofit, were also recorded. better chiller performance was observed after the retrofit. it was mainly attributed to the lower incoming condenser water temperature for chiller heat rejection (approximately • c reduction). apart from the chiller plant, there was no significant change from the baseline conditions, except the occupancy rate, which was % higher than the pre-retrofit conditions. the predictions of the calibrated models and the actual consumption figures are shown for comparison in table as well as figs. and . it should be noted that the measured values of total chiller plant energy use on april and september in the post-retrofit case were discarded, as these data were found erroneous. much effort had been made to account for the large deviation between the measured and predicted values of these two months, for example, checking on ( ) maintenance records; ( ) occupancy rate; ( ) monthly outdoor temperature; ( ) monthly relative humidity; ( ) [ ] . b seawater-cooled chiller system is not directly supported in energyplus. a "districtcooling" object with the specified leaving temperature on condenser loop is used to simulate the effect of using seawater as a heat rejection method in this study. numbers of holiday happening on weekdays; ( ) monthly billing period. the investigation concluded that the large deviation was most likely due to missing sub-meter readings but records of those readings could not be retrieved. according to the ashrae guideline, the two statistical indices, namely coefficient of variation of the root mean squared errors (cvrmse) and normalised mean bias error (nmbe), were used to assess how well the predicted values match with the measured values [ ] . the models may be declared to be calibrated when cvrmse and nmeb are less than % and % with monthly data respectively. both models in this study complied with the calibration requirements. twenty-two parameters were finally identified for sensitivity analysis. these are summarised in table . the range and intervals selected are plausible values found from the previous studies on parametric and sensitivity analysis [ , ] , with attention being paid to the selection of range and intervals, they should cover the two extreme scenarios with a reasonably narrow interval. for example, the range of annual mean dry bulb temperature was selected based on the highest and lowest values throughout the years of the hong kong observatory weather data, and the interval was selected based on the measurement error ± . • c for temperature sensor. the differential sensitivity analysis (dsa) was employed in this study, and the sensitivity influence coefficient (ic) was calculated as follows: where op is the new energy use in chiller plant; op bc is the base case energy use in chiller plant; ip is the new input parameter value; ip bc is the base case input parameter value. the base case value was same as the corresponding condition used to calibrate the pre-retrofit energy model. the advantage of using the above calculation approach is that ic is dimensionless, which can be used for comparison among different parameters. table shows the results of sensitivity analysis for the case study buildings. these parameters are ranked according to their absolute value of ic. it can be seen that the four most sensitive parameters affecting energy use are the annual mean dry bulb temperature, chiller cop, ac operating hours and annual mean dew point temperature. their ic values are at least . times larger than those of other parameters ranging from the fifth to the seventh, which include the thermostat set point for office premise, occupancy rate for office and sa premises, with the ic values ranging from . to . . other parameters, such as occupant density, lighting load, equipment load, chilled water supply temperature, ventilation rate and infiltration have relatively small effects on the building energy use in comparison with the first seven parameters. this suggests that the esco can neglect their impacts on actual energy savings even when a large deviation is observed between the pre-and postretrofit conditions. it is worth noting that the significance of the parameters may vary in different climatic conditions. for example, the ventilation rate is usually one of the most significant parameters contributing to the energy use of air-conditioning systems. however, for the hong kong weather conditions where four seasons are clearly distinct, the change of ventilation rate is insensitive to the total air-conditioning energy use on an annual basis because although the greater fresh air flow rate provides a larger rate of free cooling when the outdoor temperature is cool (thus reducing the energy use for air-conditioning during cool winter days), the saving would be compensated by the increase in air-conditioning energy use during hot summer days. high nonlinearity was found in several parameters. this means that the value of ic varies significantly from point to point. for instance, the parameter of ac operating hours is more sensitive to energy use when the presumed hour for switching off ac system is toward day-time in comparison to night-time due to the impact of solar radiation. however, the purpose of sensitivity analysis is to eliminate some parameters which are relatively less sensitive to energy use. the exact average ic value and ranking are not important in this study. the issue of high nonlinearity can be neglected when the average value of the most sensitive interval is still much lower than that of other parameters. based on the results of the sensitivity analysis, the first seven parameters were considered as the influential parameters and, for them, representative pdf were developed to simulate their yearly variations during the post-retrofit period. the selection of the representative distribution followed the three established tests, namely the chi-square test, the kolmogorov-smirnov (k-s) test, and the anderson-darling (a-d) test [ , ] . the k-s test was used when the sample sizes were less than . the chi-square test and a-d test were employed while the sample sizes equal to or more. all the calculated values from these tests were tested by the corresponding criteria values at the % significance level. when the calculated value is less than the critical value at the specified significance level, the assumed distribution can be declared as an acceptable model to describe sample data. for example, the observed data of dry bulb mean temperature (sample sizes = ) was assumed to be inferred by the normal distribution. in the k-s test, the calculated value of maximum discrepancy between the assumed and observed cumulative frequencies was . , which was less than the critical value of d˛= . n= = . at % significance level. by the k-s test, the normal distribution was verified as an acceptable model at % significance level for the dry bulb mean temperature parameter. the test results for all the selected parameters are listed in table . weather condition is one of the most critical factors affecting building energy consumption [ ] . although it is well recognised that mean temperature is generally increasing due to global warming and urbanisation [ ] , considerable variations may still be observed from year to year. for example, the location of this case study, hong kong, has a humid sub-tropical climate with four distinct seasons. in summer, the mean outdoor temperature reaches up to . • c but it can drop significantly to . • c in winter [ ] . the cooling degree-days (cdd) and heating degree-days (hdd) are and with a base of . • c, respectively [ ] . with such seasonal climate characteristics, the annual mean temperature varied from . • c to . • c within years (from to ), and the differences between the numbers of very hot days (daily maximum temperatures ≥ • c) and cold days (daily minimum temperatures ≤ • c) for two consecutive years can be as large as days (from to ) and days (from to ) respectively in hong kong [ ] . this uncertainty in yearround weather conditions can lead to volatility in energy savings for weather dependent retrofit measures. based on the latest years' daily measured data ( - ) obtained from the hong kong observatory [ ] , the four climatic variables, including annual maximum, mean and minimum daily dry bulb temperature and dew point temperature, were assigned to the most representative pdf using a distribution curve fitting technique. it is noted that the variations in diurnal temperature range is also considered in this study. diurnal temperature range is the temperature difference between the daily maximum and minimum temperature. the change in diurnal temperature range is an indication of the severity of global warming [ ] . occupancy rates in office and sa buildings vary from time to time, especially during the periods of economic growth or this sa study focused on the importance of parameters affecting the energy use of a chiller plant. the seasonal variation in these weather variables, therefore, was not included. the annual mean temperature was taken as the average value of the daily mean air temperature throughout a year. b ac operating hours (office) involves two parameters, the ac start-up time and operating duration, would be adjusted. in this study, the ac start-up time, which is : am, remained unchanged and only the operating duration was changed. c ac operating hours (sa) was assumed to be unchanged as it is very unlikely for sa operators to reduce the operating hours. d the data on occupancy rate is in terms of the annual mean percentage. the occupancy rate was converted into the number of floors being fully occupied. besides, it was assumed that a tenant rents the office floor in terms of a whole floor, instead of half-floor. similarly, the sa operator will try to occupy the whole floor for minimising the operation costs. downturn. in many epc projects, the esco and host both bear the risk of variations in occupancy, leading to uncertainty in actual energy savings. in this study, a large variation in occupancy rate was observed. in , the average occupancy rate dropped dramatically from . % to . % for the office premises and from . % to . % for the sa premises due to the economic impact of the severe acute respiratory syndrome (sars) outbreak in that year, and these figures increased gradually to nearly the highest (office: % and sa: %) in recent years. in this study, the pdfs of occupancy rate for the office and sa premises were derived from the years' data ( - ) of the developer's annual reports. to control the energy use within budget, the building owners provide tenants with air-conditioning service in fixed periods only. the operating hours of ac system for office premises in hong kong vary from buildings to buildings. in general, the ac operating hours is in line with the office working hours, which is typically from : am to : pm in hong kong. however, overtime working is very table results of chi-square, k-s and a-d tests and the assumed distribution for the selected parameters. as there is no occupancy rate of individual tower for office and sa premises in the annual report, the mean value of the whole composite buildings was used. all the parameters above are in term of annual mean. common in hong kong. there may be frequent requests for extension of ac operating hours, especially when there are changes of tenants. since the contract period is relatively long in epc projects (e.g. - years for chiller replacement), it is reasonable to expect that the operating hours in the first year of an epc contract would be different from those in the past year. therefore, the impact of possible extension or reduction of operating hours on the energy saving must be addressed. however, there are hardly any reliable records or research studies that report the long term variations in the operating hours of ac systems in buildings. an alternative way to estimate this variation is based on the ac operating hour data given by real estate agents. this approach assumed that the operating hours would be dependent on tenants' preference and relative negotiation power. as such, this study was based on the information from primeoffice to determine the pdf of operating hours. primeoffice is a property search website with the database of over hong kong office buildings. it provides the building information such as typical floor area, airconditioning hours and system types (e.g. central ac, split type) [ ] . based on the primeoffice database, the pdf of operating hours was determined. as real estate agents operate in a very competitive environment in hong kong and they pay particular attention to solicit patronage with good services, the data on this website is assumed to be adequate for the demonstration of methodology rather than reporting the actual results. the choice of indoor air temperature set-point can substantially affect the energy consumption of chiller plant [ , ] . the indoor air temperature setting can vary significantly as different occupants could have different thermal sensation to indoor environment. in the recent years, the government launched the "energy conservation charter" programme to encourage occupants to raise the indoor temperature to . • c for energy savings [ ] , but the thermostat set-point is not often adjusted as recommended. mui and wong's field survey [ ] on offices found that the average air temperature in typical office buildings is ± . • c. the pdf of thermostat set point was determined based on the survey results of mui and wong [ ] . despite the fact that this study was not focused on the variation of indoor air temperature in a single development as this case study represents, the finding was applicable since in general the decision on thermostat set point would be in relation to occupants' behaviours, instead of building characteristics and location. coefficient of performance (cop) is a primary indicator to reflect the actual energy efficiency of chillers; the higher the cop of chillers is, the less energy is consumed to provide the same amount of cooling. the performance of chiller plant will deteriorate with time of use due to two main factors: ( ) normal wear and tear over a long operating period; and ( ) contamination of chilled water tubes. masaaki et al. [ ] studied the degree of deterioration of chiller performance after years of operation. it was found that no performance deterioration was observed for the first months. after that, the cop deteriorated at an annual average of . %. the study also suggested that . % of chiller performance could be recovered when preventive maintenance, such as tube chemical cleaning, is regularly performed. the pdf of cop is difficult to determine, because the variations in the operating cop due to equipment deterioration depend on a number of factors, including operating hours, operation conditions (whether it is close to the standard operating conditions), the frequency and quality of maintenance work. as the maintenance is part of the scope of the contract in most epc projects, the esco has an incentive to ensure that the plant performance shall be maintained at the expected cop. when the plant performance is much lower than the expected cop, active maintenance, such as tube chemical cleaning, replacement of parts, would be carried out to avoid energy saving shortfall. in this case study, the existing chillers were still used after the retrofit. based on the previous study of existing chiller performance [ ] , an annual average of . % cop deterioration rate was assumed for the worst case while . % improvement of chiller performance will be used for the best case (assuming with high quality of maintenance work during the contract period). a triangular distribution was assumed for the pdf of cop. the most likely value in this pdf will be set equal to the existing cop. fig. illustrates the calculation procedures of , simulation runs. a risk analysis tool based on monte carlo simulation (@risk) [ ] was utilised to generate , common data sets of input parameters for two calibrated building energy models. the purpose of generating this common data set is to simulate all the possible cases for the yearly post-retrofit period conditions taking into account the variations in these selected parameters. in energyplus, the hong kong typical meteorological year (tmy) weather data file is used to represent the long-term typical weather condition over a year. this weather file consists of hourly climatic variable data, including dry bulb temperature, wet bulb temperature, solar radiation, wind speed, etc. in order to simulate all the possible yearly weather conditions during the post-retrofit period, this hong kong tmy weather file was modified and reproduced , times in accordance with the results of each monte carlo simulation run. the algorithm of weather adjustment is based on a "morphing" method, developed by belcher et al. [ ] who constructed design weather data for future climates. the main advantage of this method is that it preserves the characteristics of standard weather pattern after modification. in the "morphing" method, three operations: ( ) a shift; ( ) a liner stretch; and ( ) a shift and a stretch, as listed in eqs. ( ) to ( ) are used to modify the weather file. where x is the existing hourly climatic variable; x y is the absolute change in yearly mean climatic variable for the year y; ˛y is the fractional change in yearly mean climatic variable for year y; x y is the climatic variable x average over year y. in this study, the hourly dry bulb temperature (dbt) of the existing hong kong tmy weather file was morphed by a combination of a shift and a stretch to generate another set of hong kong tmy weather file. the equation for morphing is shown as follows (eq. where dbt max y , dbt y and dbt min y = yearly mean daily maximum, average and minimum temperature of energyplus weather file data respectively; tmax y , temp y and tmin y = absolute change in yearly mean daily maximum, average and minimum temperature of hong kong weather data respectively; dbt = existing hourly temperature of energyplus weather file. a stretch method was adopted to adjust the current hourly dew point temperature (dpt). as required in epw weather file, the other climatic variable-relative humidity (rh), was calculated from the hourly value of dbt and dpt using ashrae psychrometric formulae [ ] . all the morphing processes involved above were automatically performed using excel vba. by using the morphing method, a set of , modified weather files was developed, taking into account the yearly weather variations. after the generation of , tmy weather files, jeplus, an open-source parametric analysis tool for managing the energyplus simulations, was used to automatically substitute the base case value of two calibrated models with the results of monte carlo simulation. based on the representative pdf of those seven influential parameters, a group of values representing one of the post-retrofit conditions is randomly generated using the latin hypercube sampling method (please refer to fig. ). to instruct jeplus running all the possible conditions of the post-retrofit period, a csv-styled text file containing , different values of each influential parameter was created. by incorporating the calibrated energy model, tmy weather files and a csv-styled text file, jeplus can simultaneously perform the eight instructed simulations at maximum in each run, and the simulation results are automatically grouped together for a probabilistic analysis of actual energy savings [ ] . the , energyplus iterations ( , iterations for each model) were performed in computers with two quad-core processors, taking h to complete the calculation. in this demonstration, timesteps per hour was used and the conduction transfer function was adopted as a heat balance algorithm in energyplus. a point worth noting is that the common data set was applied to all selected parameters for both models, except the parameter "overall cop of chiller plant" in the pre-retrofit model, which remains unchanged as the pre-retrofit condition. figs. and show the actual energy saving for all possible combination of the selected parameters and the fitted distributions of energy savings in the case study buildings. the possible energy savings after year retrofit period ranges from , kw h ( . %) to , kw h ( . %) with % statistical significance, which is best fitted by a weibull distribution with a mean , kw h ( . %) and a standard deviation , kw h ( . %). this suggests that the variations in actual yearly energy savings can be significant. the maximum energy savings can be times higher than the minimum one. the results also provide information on the probability of energy saving shortfall when a certain amount of energy savings is anticipated. for example, only by a . % chance the esco will successfully achieve the mean value of energy saving per year , kwh ( . %) for the replacement of heat rejection system in this study. further studies are needed to benchmark this sort of probability values when data on more buildings are available, but since the objective of this paper is to demonstrate a plausible methodology, it still serves its purpose. this paper proposes a simulation-based method to evaluate the probability of energy saving shortfall taking into account the variations in the influential parameters. a real case study of replacement of heat rejection system for a central chiller plant in hong kong is used to demonstrate the application of this probabilistic method. the result shows that the possible energy savings after a -year retrofit period can range from , kw h ( . %) to , kw h ( . %) with % statistical significance. this assessment method can be useful for evaluating the performance risks when certain amount of energy saving is guaranteed for retrofit measures. it should be noted that the confidence of the result relies on the representativeness of two building energy models, the selection of proper ranges and intervals for sensitivity analysis, as well as the goodness-of-fits of probabilistic distribution functions for selected parameters. besides, this study only focuses on the energy savings from the retrofit work. however, the financial benefits from epc projects also include the avoided-cost savings, for instance, a reduction in operation and maintenance costs. the future works on the risk assessment in epc projects should include the variations in such avoided-cost savings. with the use of this proposed methodology, the risks of epc will be better understood and managed. energy saving by realistic design data for commercial buildings in hong kong world business for sustainable development (wdcsb), energy efficiency in buildings: transforming the market an international survey of the energy service company (esco) industry high-efficiency hvac systems, and energy efficient lighting: market analysis and forecasts directive / /ec of the european parliament from volatility to value: analysing and managing financial and performance risk in energy savings projects the investment risk in whole-buildings energy efficiency upgrades projects actuarial pricing of energy efficiency projects: lessons foul and fair evolution of the u.s. energy service company industry: market size and project performance from promoting energy efficiency investments with risk management decision tools management measurement & verification of performance contracting american society of heating refrigerating and air-conditioning engineers, measurement of energy and demand savings, ashrae guideline - m&v guidelines: measurement and verification for federal energy projects international performance measurement & verification protocol sensitivity analysis techniques for building thermal simulation programs sensitivity analysis of energy performance of office buildings multi-parameter building thermal analysis using the lattice method for global optimisation energy efficient building design using sensitivity analysis-a case study sensitivity analysis and energy conservation measures implications a comprehensive analysis of the impact of occupancy parameters in energy simulation of office buildings probability concepts in engineering: emphasis on applications in civil & environmental engineering practical application of uncertainty analysis comparative analysis of support mechanisms for renewable energy technologies using probability distributions uncertainty sensitivity analysis of building performance using probabilistic climate projections: a uk case study, automation in construction uncertainty analysis in building performance simulation for design support method and case study of quantitative uncertainty analysis in building energy consumption inventories constructing design weather data for future climates developing a modified typical meteorological year weather file for hong kong taking into account the urban heat island effect height construction costs of residential high-rise buildings in shanghai energyplus energy simulation software, version american society of heating refrigerating and air-conditioning engineers, standard method of test for the evaluation of building energy analysis computer programs, ashrae code of practice for energy efficiency of building services installation, the hong kong special administrative region climate change in hong kong in, the hong kong special administrative region monthly climatological normals for hong kong ashrae handbook: fundamentals, ashare climatological information services, extracts of climatological data, the hong kong special administrative region diurnal temperature range as an index of global climate change during the twentieth century commercial property for lease and for sale assessing energy performance in the latest versions of hong kong building environmental assessment method (hk-beam) a study on the energy penalty of various airside system faults in buildings electrical and mechanical services department, energy saving charter neutral temperature in subtropical climates-a field survey in air-conditioned offices electric chiller performance evaluation based on actual operating data for energy service business palisade corporation, @risk, version . . performing omplex parametric simulations with jeplus the work described in this paper was fully supported by a grant from the general research fund of the research grants council of the hong kong special administrative region (project no. polyu / e) key: cord- -ixozph authors: yip, paul; chen, mengni; so, bing kwan; lam, kwok fai; wat, kam pui title: optimal strategies for reducing number of people in the social security system date: - - journal: int j environ res public health doi: . /ijerph sha: doc_id: cord_uid: ixozph providing social security to the population in need has become a major expenditure for many governments. reducing the number of dependents in the social security system and maintaining a dynamic economically active population is a high priority concern for policymakers. a good understanding of the dynamics of the social security system—specifically, who enters and who exits the system—would be helpful for formulating effective interventions. here, we made use of the data of hong kong’s comprehensive social security assistance (cssa), which is currently a basic welfare scheme in hong kong that provides supplementary payments to households that cannot support themselves financially. we proposed a stochastic model to examine the in- and out- movement in the cssa scheme and conducted elasticity analyses. the elasticity analyses allowed us to identify the potential target groups of people that would lead to the largest reduction in the number of the cssa recipients in the system. this analytical method can also reveal whether policies would be more effective in preventing people from entering the cssa system or helping them leave the cssa scheme. our analyses suggest that targeting those aged – with children would have the largest impact. additionally, we found that policies that aim to prevent this group from entering the cssa system would be more effective in reducing the number of cssa recipients compared with policies that aim to help them exit. in contrast, for the younger age group of – , policies that help them leave cssa would be more effective than policies that prevent them from entering cssa. providing employment for those unemployed in this younger group would be more effective. the results indicate that by tailoring measures to specific subgroups, the overall number of cssa recipients would be reduced, thereby improving the efficiency of hong kong’s social security system, which has accounted for more than . % of hong kong government expenditure in , amounting to more than hkd billion. "leave no one behind" is the overarching principle of the united nations' sustainable development goals [ ] . ending poverty everywhere, in all its forms, is the first of the sustainable development goals (sdg). in signing the sdg agenda , governments around the world have committed to achieving this goal over the coming years. hong kong is one of the richest cities in the world with an impressive gdp of usd , , but with a large gini coefficient of . , and thus the issue of poverty deserves special attention. the poverty line in hong kong is set at % of the median until , hong kong was a british colony for more than years (since ). the social security system in hong kong was shaped by the laissez-faire philosophy under the previous colonial regime. the concept of self-reliance via employment is deeply rooted in the psyche of the hong kong population, and the so-called hong kong "lion rock spirit" captures an ethic of hard working and mutually helping one another in the community. only the very needy and vulnerable families would receive support by the government. thus, hong kong's welfare system was perceived as a typical example of the residual model of welfare, which views the government welfare provision only as a last resort. the laissez-faire philosophy and residual welfare model were also compatible with chinese confucian values, which emphasize filial piety, respect for older people, love for one's family, self-restraint, shouldering collective responsibility, mutual help, and so on. chiu and wong ( ) [ ] have argued that confucian ideology has been used by the hong kong government as "a means to contain social welfare costs", as well as to justify the residual welfare model. on july st of , the sovereignty over hong kong was returned back to mainland china and the city has become a special administrative region of the people's republic of china (hksar). under the principle of "one country, two systems", hong kong has enjoyed a high degree of autonomy and is responsible for its domestic affairs including tax system. the hksar government does not have to contribute any revenue towards the central government. since , the social policies in hong kong have been not only shaped by the laissez-faire philosophy that were "inherited" from the colonial regime, but also constrained by the basic law that was issued after the handover to china [ ] . according to the basic law, the hong kong government can only increase its public expenditure on social welfare within the limits of the budget surplus [ ] . thus, social policies have become sensitive to the government budget. since , the government experienced years of budget deficit, from - to [ ] [ ] , which was related to the asian financial crisis and the severe acute respiratory syndrome (sars) epidemic. during this period, the low-income group suffered most from the two economic shocks. the rising social welfare needs of low-income families greatly increased government spending, and consequently new social policies to expand and diversify the social welfare system had to be suspended [ ] . the comprehensive social security assistance (cssa) is the most important welfare program in hong kong. previously, this social security was called "public assistance", which was introduced in and modified from the british national assistance act. public assistance aimed to help the aged and the sick to maintain a basic living standard with a minimal allowance. it was in that public assistance was renamed cssa. the applications of cssa have to go through income and assets means tests. in the first year (i.e., ), the number of cssa cases was , and the number of cssa recipients was , . there can be more than one recipient in one case, as the household is treated as a case unit and all the members within the household can be recipients. figure shows the trends of cssa cases and recipients over the period of - . the number of cases rapidly increased and reached a peak in the year (of , ); since then, it has steadily declined to , in . the number of recipients had a similar trend, with a dramatic increase in the years of of , of , of , and of . in of and on july st of , the sovereignty over hong kong was returned back to mainland china and the city has become a special administrative region of the people's republic of china (hksar). under the principle of "one country, two systems", hong kong has enjoyed a high degree of autonomy and is responsible for its domestic affairs including tax system. the hksar government does not have to contribute any revenue towards the central government. since , the social policies in hong kong have been not only shaped by the laissez-faire philosophy that were "inherited" from the colonial regime, but also constrained by the basic law that was issued after the handover to china [ ] . according to the basic law, the hong kong government can only increase its public expenditure on social welfare within the limits of the budget surplus [ ] . thus, social policies have become sensitive to the government budget. since , the government experienced years of budget deficit, from - to - , which was related to the asian financial crisis and the severe acute respiratory syndrome (sars) epidemic. during this period, the low-income group suffered most from the two economic shocks. the rising social welfare needs of low-income families greatly increased government spending, and consequently new social policies to expand and diversify the social welfare system had to be suspended [ ] . the comprehensive social security assistance (cssa) is the most important welfare program in hong kong. previously, this social security was called "public assistance", which was introduced in and modified from the british national assistance act. public assistance aimed to help the aged and the sick to maintain a basic living standard with a minimal allowance. it was in that public assistance was renamed cssa. the applications of cssa have to go through income and assets means tests. in the first year (i.e., ), the number of cssa cases was , and the number of cssa recipients was , . there can be more than one recipient in one case, as the household is treated as a case unit and all the members within the household can be recipients. figure shows the trends of cssa cases and recipients over the period of - . the number of cases rapidly increased and reached a peak in the year (of , ); since then, it has steadily declined to , in . the number of recipients had a similar trend, with a dramatic increase in the years of of , of , of , and of . in of and , when the asian financial crisis struck hong kong, the number of recipients had increased by , and , , respectively. number of cssa cases and recipients year case recipients figure shows the age composition of the recipients. as shown, in , those aged and above accounted for almost % of recipients, whereas those aged - and under occupied about % and %, respectively. the proportion of recipients aged - initially rose continuously, reaching about % in ; since then, it has started to decline and the proportion was about % in . as the population continues to age rapidly due to low fertility and long life expectancy, the proportion of recipients aged and above is expected to increase. int. j. environ. res. public health , , of figure shows the age composition of the recipients. as shown, in , those aged and above accounted for almost % of recipients, whereas those aged - and under occupied about % and %, respectively. the proportion of recipients aged - initially rose continuously, reaching about % in ; since then, it has started to decline and the proportion was about % in . as the population continues to age rapidly due to low fertility and long life expectancy, the proportion of recipients aged and above is expected to increase. such a large share of spending on cssa and its rate of increase have become a concern for the hong kong government, especially in the years of the asian financial crisis and sars epidemic, such a large share of spending on cssa and its rate of increase have become a concern for the hong kong government, especially in the years of the asian financial crisis and sars epidemic, such a large share of spending on cssa and its rate of increase have become a concern for the hong kong government, especially in the years of the asian financial crisis and sars epidemic, when the budget turned to a deficit. the government did take steps to control the expenditure on cssa and balance their budget by reducing the value of cssa payments and the number of recipients. theoretically, reducing the number of recipients can be achieved either by preventing people from entering the cssa system or helping them leave the system. the "entering approach" often influences a relatively larger number of the population at risk of poverty, preventing "potential candidates" from falling into cssa with more universal measures. the universal measures often include minimum wage, universal health insurance, subsidized education, public housing, and so on, from which both cssa recipients and non-cssa people can benefit [ ] . in particular, the universal cash handout scheme in hong kong is a very typical example. the hong kong government introduced scheme hkd and scheme hkd in and , respectively. under these schemes, any hong kong permanent resident aged and above was eligible to get a lump-sum payment of hkd and hkd in and , respectively. in contrast, the "leaving approach" is more likely to affect a relative smaller group of people that are unemployed, in low-paid work, or single parents, helping them get out of the system with more focused measures. the focused measures include single parent allowance, transportation subsidy for low-income families, job training programs for the unemployed, and so on [ ] . the hong kong government seemed to have adopted an "entering approach" in the s, but the specific means of preventing people from entering was controversial. before , hong kong residents could apply for cssa if they had lived in hong kong for at least year. in , the requirement for residence was then raised up to years, effective from until . this revision was mainly driven by concerns about the budget shortfall [ ] . scholars also think that the government pursued the "entering approach" by blaming the poor for their laziness using the media, so that they were discouraged to apply for cssa [ , ] . this created a psychological hurdle for those physically able adults and made them turn away from cssa voluntarily. wong ( ) [ ] argued that the image of "laziness" and "dependency" constructed (whether intentionally or unintentionally) for the cssa recipients actually reflected "a failure rather than a success in fighting against poverty". the cssa is meant to provide timely help for those needy families such that they still can receive the necessary financial support while looking for employment. it does not mean to create some dependence on the system, and those seeking help should not be stigmatized. furthermore, it is always the children from cssa families who would need more support to break up intergenerational poverty. meanwhile, it should be emphasized that "welfare dependency" is a very common problem that many social security systems would face or try to avoid [ ] [ ] [ ] . when the incentives to take and sustain jobs are not strong enough, people would continue claiming benefits from the social security system as they are often more secure and attractive than employment; thus, it would create a culture of "dependency", "laziness", or "worklessness", leading to "excessive and ineffective public expenditure", as well as "persistent and prevalent poverty" [ ] . to reduce such "welfare dependency", an effective "leaving approach" may help to incentivize cssa recipients to return to and survive in the labor market. the poverty commission in hong kong has advocated social enterprises to play a role in poverty alleviation, particularly helping welfare dependents become self-sufficient, as social enterprises would provide more opportunities to the disadvantaged, as well as improve their skills and employability [ ] . it is important to consider whether the "entering approach" is indeed more effective than the "leaving approach" in reducing the number of cssa recipients in hong kong. very few studies have provided evidence for the "entering approach". furthermore, without reducing the cssa payment and restricting the eligibility, is there any better way to control the expenditure on cssa? which group of people and in what approach should the government intervene so that the number of recipients can be effectively reduced? this paper tries to answer these mostly unexplored questions. specifically, by modelling the dynamics of the cssa system in a markov chain process and performing an elasticity analysis, we aimed to identify the potential target group and the group-specific approaches. the findings can shed some light on how to enhance and optimize the social security system in hong kong. the data required for the analysis included ( ) the age-specific number of people who entered the cssa system during - , ( ) the age-specific number of people who left the system during - , ( ) the age-specific population in , and ( ) the number of births by mothers in terms of age group in . on the basis of these data, we estimated the age-specific transition probabilities; that is, the probabilities of leaving cssa and the probability of entering cssa. all of the data are from the hong kong census and statistics department (hkc&sd). we modelled the dynamic of people moving in and out of the cssa system using a stochastic process (markov chain process). this method has been increasingly used in labor economics and demographic research, especially in evaluating social policies [ ] [ ] [ ] [ ] [ ] . we first present a simplified model. suppose in a certain year, the probability of entering the system is p t and the probability of leaving the system is q t . let x t be the proportion of cssa recipients in the total population at time t. therefore, we can simply formulate the inflow and outflow of cssa recipients in equation ( ). where a is a × matrix, the proportion of cssa recipients in the total population, x t+ , can be reduced either through reducing the probability of entering cssa, p t , or through increasing the probability of leaving cssa, q t . to investigate whether the former or the latter approach is more effective in reducing the number of cssa recipients is of great importance to policymakers. in order to answer this question, we introduced the concept of elasticity. elasticity is originally a concept in economics. in economics, price elasticity, for instance, measures the impact on the demand of a product when its price changes, that is, percentage change in the quantity demanded of one product in response to percentage change in the price. very often, it is precisely interpreted as the percentage change of demand per % change in the price [ ] . the concept of elasticity has recently been adopted by some scholars to evaluate the targeting of policies, for example the targeting of family polices in singapore, taiwan, and australia [ ] [ ] [ ] . analogously, here we define the elasticity as the ratio of percentage change of x t+ to the percentage change of any of the parameters (p t or q t ). the larger the elasticity, the more influential the parameter to x t+ . the elasticity with respect to p t and q t can be formulated as follows: ( ) by comparing the absolute values of δ p t and δ q t , we will know whether the "entering" or "leaving" approach is more effective in reducing the number of cssa recipients in a certain year. in reality, the probability of leaving or entering the cssa system often varies across different age and socioeconomic groups. as the data of cssa recipients by socioeconomic status is not available, we cannot include the socioeconomic groups in our analysis. thus, we further elaborated our model by considering age to better reflect the real dynamics of the cssa system in hong kong. let x in this study, we restricted our attention to those aged below , because those cssa recipients aged and above have a high chance of leaving the cssa system due to death. the financial situation of older adults, and particularly those over the retirement age of , would also typically show little change due to the relatively low employability of older adults. on the basis of the data from hkc&sd, we estimated the transition parameters p (i) t and q (i) t for year age-specific groups (covering the ages of - ). within the age group, those aged deserve special attention. according to the rules under the cssa system, the newborns of a cssa recipient will become cssa recipients directly. on the basis of the assumptions that the birth rates of the cssa recipients and non-cssa people are the same, and that the births are from women aged - , x ( ) t and y ( ) t can be formulated by equation ( ). are the corresponding age-specific birth rates at time t. certainly, b ( ) . the goal of our analysis was to investigate which group should be targeted and in which approach of "leaving" or "entering", so that the overall proportion of cssa recipients can have the largest reduction. let x denote the overall proportion of the cssa recipients in the population aged under , which can be calculated from the following formula: where w (i) t refers to the proportion of the age group i in the total population aged under at time t, and i= w t was estimated on the basis of the age-specific population in from hkc&sd. to achieve the goal, we estimated the elasticity with respect to p (i) t and q (i) t from the following formulae, which were modified from equations ( ) and ( ): moreover, to better understand the moving-in and -out of the cssa system, we calculated the probability of a cssa recipient aged i to first exit the system at or before the age of , as well as his/her mean time of staying in the system before the first exit. equations ( ) and ( ) were used to estimate the probability and the mean time. i) = − − q (i) t − q (i+ ) t · · · − q ( ) t ( ) mean time = × q (i) t + × q (i+ ) t × − q (i) t + · · · +( − i) × q ( ) t × − q ( ) t · · · − q (i) t( ) the estimated age-specific probabilities of entering and leaving the cssa system are shown in table . the probability of leaving was found to be much higher than the probability of entering across all the ages. the - age group has the highest probability of leaving and the lowest probability of entering the cssa system. except for the two youngest age groups, the probability of leaving cssa declines with the increase of age, indicating the increasing difficulty of raising their income above the level of the threshold. on one hand, this declining trend may be due to the fact that the family size will increase with people's age, and thus it would become more difficult to move all the family members out of the cssa system. on the other hand, previous research shows that in hong kong, as men and women get older, particularly after age , upward mobility of earnings declines while downward mobility of earnings increases [ ] . workers in the lowest income quintile are more likely to be trapped at the bottom, experiencing no earning mobility [ , ] . moreover, the declining probability of leaving for the two youngest age groups (i.e., ages of - and - ) is very much related to the parents' probability of leaving. parents of children aged - are more likely to be older, in the s and s, and that is probably why the leaving probability of the - age group is lower and very close to that of the - and - age groups. regarding the probability of entering cssa, the - and - age groups were found to be at the highest level-much higher than the other age groups. this was because these two groups are too young to participate in the labor market and their economic situation often depends on their parents. once their parents' incomes fall below the threshold level of cssa, they become cssa recipients directly. hence, these young people are indirectly entering the cssa system. thus, reducing their probability of entering should not directly aim at these young dependents but at improving incomes of their parents who are often in the age range of - . maintaining the economic environment by keeping the unemployment rate low is important for middle-aged workers. table shows the probability of a cssa recipient first exiting the system before age and the mean duration of staying in the system. it is encouraging to see that the probabilities of first exit among those aged under are higher than . , implying that almost all of them will leave the cssa system before age . there was a significant decline in the probability of first exit after age . this is very consistent with the age pattern shown in table . the probability dropped to . for those aged and . for those aged . this is because there is much less time for them to leave the cssa before the cutoff age of . regarding the mean time of staying in the system, children under age were found to have the longest duration. the mean time was found to decrease to about . years for those in their s and then starts to rise again in the age range of - . those in their s have a much shorter duration of staying before they first leave the system. on the basis of the age-specific probability of entering and leaving cssa, we performed the elasticity analysis. the results (in absolute values) are shown in table increased by . , the overall proportion of cssa recipients would decrease by . (= . × . ). from these results, it seems that preventing people aged - from entering the cssa system has a larger impact; that is, the "entering" approach would be more effective in reducing the number of cssa recipients in . however, it should be noted that it is impossible and unrealistic to achieve a decrease of . in p is only . and a decrease of . will make it negative. in reducing the number of cssa recipients; for the - and - age group, helping the cssa recipients leave the system will have a larger impact (see the last column in table ). in sum, these results suggest that targeting the age group of - through the "entering approach" would lead to the greatest reduction in the number of cssa recipients, as aiming at this group would also effectively prevent those aged - from entering the cssa system. this study investigated the targeting of the social security system in hong kong by evaluating the cssa scheme, which is the fundamental welfare program. we have made use of the markov chain process to model the dynamics-the inflow and outflow-of the cssa system. we conducted elasticity analyses to identify the potential target group and the appropriate approaches for different subgroups classified by age. the results have revealed that the largest elasticity was in the - age group, meaning that targeting children at this age will lead to a largest decrease in the number of cssa recipients. currently, child poverty is a serious issue in hong kong. in , before government intervention, the poverty rate among children aged below was about . %, much higher than many other developed societies [ , ]. as child poverty often results from parents' low income and unemployment, policies that support households with children would be desirable. more precisely speaking, the results suggest that targeting those aged - with children by decreasing the risk of entering cssa would have the largest impact on the number of cssa recipients. studies on child poverty in hong kong have found that family structure is a strong predictor. it was found that children from immigrant families are more likely to live below the poverty line in hong kong due to low education of parents, high unemployment rate of mothers, and low payment of parents' jobs [ ] . moreover, children living with single parents have high risk of poverty; the poverty gap between children with single parents and children with two parents has been widening in recent decades [ ] . the ethnic minority families such as pakistani, nepalese, and other south asian countries also have higher child poverty rates, as a result of discrimination in the education system and labor market due to the language barriers faced by their parents [ ] . poverty is found to have a significant impact on children's psychological well-being-in hong kong, children in poverty have reported lower levels of self-esteem and more depressive symptoms, and they are more likely to live in public housing which is often more crowded, having poor hygiene and lack of facilities [ ] . food insecurity, as well as limited educational opportunities and learning resources would have a therefore, compared to the rates of change, the elasticity that takes into account the feasibility of changing the parameter is preferable. as shown in table , the elasticity to the probability of leaving in the - age group δ q ( − ) t was . , meaning that given % increase in the probability of leaving (i.e., an increase of % × . ), the proportion of cssa recipients would reduce by . %. the elasticity to the probability of entering the group δ p ( − ) t × was . , meaning that given a % decrease in the probability of entering (i.e., a decrease of % × . ), the proportion of cssa recipients would reduce by . %. thus, according to the elasticities, increasing the probability of leaving would have a greater impact, indicating that the "leaving approach" rather than the "entering approach" is more effective for the age group - . as shown in figure , the elasticities of the leaving probabilities decline with age, implying that the "leaving approach" is more effective in younger age groups than in older groups, as the employability of young people is much higher than their older counterparts and earning a salary through employment is the most effective way to leave the cssa system. the elasticities of entering probabilities also showed a decreasing trend over ages, although the - and - age groups had the lowest elasticities. this means that the "entering approach" for these two groups is relatively less effective than in other age groups. the age pattern of the elasticities showed that targeting younger age groups would make a larger difference than targeting older groups. therefore, intuitively, it may seem most effective to target the - age group. however, instead of focusing on these young dependents, attention should be paid to their parents who are often in the age group of - and - . furthermore, elasticities of entering probabilities were larger than leaving probabilities in the - , - , and - age groups, whereas the opposite pattern was shown in the - and - age group. these findings inform us that for the - , - , and - age group, preventing them from entering the cssa system would be more effective in reducing the number of cssa recipients; for the - and - age group, helping the cssa recipients leave the system will have a larger impact (see the last column in table ). in sum, these results suggest that targeting the age group of - through the "entering approach" would lead to the greatest reduction in the number of cssa recipients, as aiming at this group would also effectively prevent those aged - from entering the cssa system. this study investigated the targeting of the social security system in hong kong by evaluating the cssa scheme, which is the fundamental welfare program. we have made use of the markov chain process to model the dynamics-the inflow and outflow-of the cssa system. we conducted elasticity analyses to identify the potential target group and the appropriate approaches for different subgroups classified by age. the results have revealed that the largest elasticity was in the - age group, meaning that targeting children at this age will lead to a largest decrease in the number of cssa recipients. currently, child poverty is a serious issue in hong kong. in , before government intervention, the poverty rate among children aged below was about . %, much higher than many other developed societies [ , ] . as child poverty often results from parents' low income and unemployment, policies that support households with children would be desirable. more precisely speaking, the results suggest that targeting those aged - with children by decreasing the risk of entering cssa would have the largest impact on the number of cssa recipients. studies on child poverty in hong kong have found that family structure is a strong predictor. it was found that children from immigrant families are more likely to live below the poverty line in hong kong due to low education of parents, high unemployment rate of mothers, and low payment of parents' jobs [ ] . moreover, children living with single parents have high risk of poverty; the poverty gap between children with single parents and children with two parents has been widening in recent decades [ ] . the ethnic minority families such as pakistani, nepalese, and other south asian countries also have higher child poverty rates, as a result of discrimination in the education system and labor market due to the language barriers faced by their parents [ ] . poverty is found to have a significant impact on children's psychological well-being-in hong kong, children in poverty have reported lower levels of self-esteem and more depressive symptoms, and they are more likely to live in public housing which is often more crowded, having poor hygiene and lack of facilities [ ] . food insecurity, as well as limited educational opportunities and learning resources would have a negative impact on the development of children from poor families, creating intergenerational poverty in hong kong [ ] . therefore, it is very important to identify the reasons of falling into the cssa system and barriers to exit among households with children. single parenthood, unemployment, and low-earnings are the major reasons for physically-able adults becoming cssa recipients. the latest poverty study in shows that poverty among those who are working was only . % in comparison to . % in the general community [ ]. providing jobs and enhancing job earnings for the age group of - would effectively reduce the number of cssa recipients. the hong kong government has initiated the public transport fare subsidy scheme to enhance people's ability to look for employment across districts [ ] . the government also provides additional support for families-especially single-parent families-to work part-time and look after their children after work. of course, the employment remuneration conditions should be improved so that working parents can earn enough to support the family without the need of cssa. the introduction of a minimum wage by the hong kong sar government in has helped to narrow the income gap, despite the fact that the minimum wage is still at a very low level of about hkd . (about usd . ) per hour. in many western countries, the minimum wage is substantially higher (e.g., usd . in australia, usd . in the united kingdom), despite the fact that hong kong's gdp per capita of usd , actually ranks higher. thus, it is important to examine the minimum wage structure, especially for those in low-skilled jobs, to improve their quality of life. meanwhile, different subgroups call for different approaches. the "entering approach" is not always most desirable for all the subgroups. it is found that for the - age groups, policies that aim to help people leave cssa will be more effective than policies that aim to prevent people from entering cssa. according to the hong kong poverty situation report , the unemployment rate among the young people - is relatively higher than the general population. on the other hand, for those who are employed, young households have the highest proportion of high-skilled workers and the lowest poverty rate [ ]. by upgrading working skills of young cssa recipients, young adults can enhance their employability and secure jobs with better earnings, so that they can support themselves without cssa. diversifying the economic and working opportunities is also of great importance in improving the employability of our young people. most of the economic activities in hong kong are in the professional, financial, and service sectors, and limited opportunities are available in other sectors, such as creative industries and local startups. the excessive rental cost in hong kong has been found to be a barrier for young people to start their own business. it is important for the government to provide initial support for these young entrepreneurs at the early stage of their career development. meanwhile, for the - age groups, policies that aim to prevent people from entering cssa will be more effective than policies that aim to help people leave cssa. people of these ages often have other family members to care for, either young children or old parents, and sometimes both. more often, they have jobs but the earnings are not adequate to cover the living expense of the whole family, and thus all members in the household become cssa recipients. in this case, policies that can increase the family income can prevent them from entering cssa. we should try to maintain or enhance the employability of these groups of people as a matter of importance. keeping them in the job is important for poverty alleviation. it will be difficult for the unemployed individuals to reenter to the workforce, especially for those who are not professionals. the bargaining power to aim for better working conditions would also be limited for the low-skilled workers as there are plenty in supply due to the current migration policy, with there being an influx of migrants of per day from mainland china entering into hong kong. the wage of the low-skilled worker has been lagging behind the economic growth. hong kong still has one of the largest poverty gaps among the high income societies with a gini coefficient of . [ ] . it is important to improve the wage level, especially for the low-skilled workers in hong kong. the minimum hourly wage is hkd . (usd . ), which is one of the lowest in comparison to other oecd (i.e., the organization for economic co-operation and development) countries. currently, the individual-based work incentive transport subsidy (i-wits), to some extent, can help middle-aged adults broaden their horizons for better job opportunities across the whole territory [ ] . in addition, the working family allowance can provide extra income to households with children. the results have provided insights into the improvement of the cssa system in terms of accurate targeting. it should be emphasized that the probability of entering and leaving cssa, as well the elasticities with respect to these probabilities, should be monitored frequently and closely so that a more timely response can be in place to improve the efficiency of cssa. in spite of the positives, there are some limitations in this study. first, due to data limitations, we were only able to investigate the targeting groups by age, and did not include the subpopulations by socioeconomic status (e.g., education, employment, occupation). future research can assess the role of different socioeconomic subgroups in reducing the number of cssa recipients, with better data access. apparently, the young graduates from universities have less financial responsibility towards their parents and they can afford to have some gap years before graduation and employment. for the young professionals, once they work, it would be easier for them to leave poverty. second, we did not take into account gender difference. the number of female cssa recipients was found to often be larger than male recipients, which is mainly the contribution of women's overrepresentation in the "single-parent" case under cssa [ ] . for example, in , . % of single-parent recipients were female, most of whom were divorced or separated, in the age of - [ ] . however, due to a lack of gender-specific data, we were unable to examine whether the elasticities were different between men and women, and how big the difference was. third, we only restricted our analysis to those under age and did not consider the elderly population due to limited information of the elderly people leaving cssa because of death. fourth, the markov chain and elasticity analyses were based on several assumptions (e.g., assumption of the same birth rates between cssa recipients and non-cssa people), and consequently they did not fully model the exact dynamics of the cssa system. fifth, we did not take into consideration the differential cost in achieving the same unit of the entering and exiting approach. however, this method is still a very useful tool to assess the targeting of the social security system and it can be further elaborated if more information about the cssa recipients and employment data is available. the propose model provides empirical evidence to identify the potential target groups of people that would lead to the largest reduction in the number of the cssa recipients in the hong kong social security system. this analytical method has also revealed whether policies would be more effective in preventing people from entering the cssa system or helping them leave the cssa scheme. despite the limitations of the stochastic model, it helps to improve the effectiveness of the social security system in hong kong. poverty and income inequality have become one of the major causes of the recent months of social unrest in hong kong in - . the government has been increasing its expenditure on welfare spending. sometimes, the improvement is still quite limited. our model can be used as a tool to examine its effectiveness of any poverty program with the aim to reduce the number of cssa recipients. author contributions: manuscript preparation and data analysis-m.c., b.k.s., k.f.l. and k.p.w.; leading the investigation as the pi for the project, critical review and final approval of the paper-p.y. all authors have read and agreed to the published version of the manuscript. funding: this research was funded by the hong kong government: sppr- . the common welfare: hong kong's social services social security inequality and the third world the - budget the basic law of the hong kong special administrative region of the people's republic of china; the constitutional and mainland affairs bureau speech by the chief executive in delivering "the chief executive's policy address" to the legislative council the social security system in hong kong: establishment and readjustment of the liberal welfare model the failure of social security in alleviating poverty in hong kong changes in social policy in hong kong since : old wine in new bottles? from familistic to confucian welfare local policy in global politics: the limit of anti-poverty policy in hong kong nations. family-oriented policies for poverty reduction, work-family balance and intergenerational solidarity social mobilization, blame avoidance, and welfare restructuring in hong kong resisting the neo-liberal poverty discourse: on constructing deadbeat dads and welfare queens workfare in the world's freest economy telling stories of st century welfare: the uk coalition government and the neo-liberal discourse of worklessness and dependency the social impact of work-integration social enterprise in hong kong for whom are permanent jobs off limits? a markov-chain-based analysis of individual labor market dynamics comparative analysis of labor market dynamics using markov processes: an application to informality a new method of identifying target groups for pronatalist policy applied to australia identifying the most influential groups in determining singapore's fertility an elasticity analysis of the effectiveness of pronatalist measures in taiwan principles of microeconomics; south-western cengage learning special topic enquiry on earnings mobility; school of economics and finance social mobility in hong kong how to break the cycle of child poverty in hong kong, where one in five children are poor. south china morning post familial effect on child poverty in hong kong immigrant families child poverty in hong kong single-parent families the effect of poverty and income disparity on the psychological well-being of hong kong children social assistance programs and child poverty alleviation-a comparison between hong kong and mainland china associations between commuting and well-being in the context of a compact city with a well-developed public transport system women's commission. hong kong women in figures hkcsd. statistics on comprehensive social security assistance scheme this article is an open access article distributed under the terms and conditions of the creative commons attribution (cc by) license the authors are grateful for data supplied by the social work department and the census and statistics department of the hong kong sar government and the many useful comments from the reviewers. the research is supported by the chief executive community project for poverty alleviation and the hong kong charities trust. the authors declare no conflict of interest. the funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results. key: cord- - xq dpg authors: chang, chia-chien; yang, alan h. title: weaponized interdependence: china's economic statecraft and social penetration against taiwan date: - - journal: orbis doi: . /j.orbis. . . sha: doc_id: cord_uid: xq dpg nan how do great powers utilize economic and social instruments to coerce the other countries? in this section, we elaborate the theories of economic statecraft and social penetration. economic statecraft and asymmetrical interdependence. china is not the first great power to resort to economic statecraft and societal penetration in pursuing national ambition. at the end of world war ii, the political economist albert o. hirschman published national power and the structure of foreign trade, analyzing how foreign trade could be used as an instrument of national power. the theme of hirshman's book is nazi germany's strategy to expand its trade and political influence during the s. hirschman pointed out that the gain from "seemingly harmless" trade relations can result in the dependence of the country that receives the traded goods. prior to world war ii, nazi germany had already launched "bloodless invasions," using economic carrots to penetrate the political systems and societies of hungary, bulgaria, romania, and others. nazi germany's economic practices, including the export of capital, personnel, and enterprises, had created a dense network of interests and customers with the result of rendering eastern and southeastern europe subservient to nazi germany. although hirschman was writing against the backdrop of nazi germany's economic aggression, his work has a broader implication for international relations today. hirschman elucidated that trade relations, or economic interdependence broadly defined, could be used as a means of political pressure and leverage because economic interdependence is usually asymmetrical, suggesting that in such an economic relationship one state is more dependent on the other. and political power and dominion arises out of the asymmetry. in international relations, power is the crucial "currency" of great power politics, and states compete for it among themselves. therefore, great powers constantly pursue asymmetrical economic relationships in order to create dependence and political dominance. david baldwin, senior political scientist in the woodrow wilson school at princeton, refers to such pursuit of power through economic means as economic statecraft, defined as influence attempts relying on resources which have a reasonable semblance of a market price in terms of money. economic statecraft, baldwin contends, has been practiced for centuries. and the utility of economic statecraft has been systematically underestimated. today, it is all too common for great powers to resort to economic statecraft and social penetration to further their national interests. nuclear program. the russian federation launched cyber warfare to destabilize ukraine's democratic order. moreover, russia misinformed and polarized u.s. voters by extensive propaganda and penetration of social media platforms. as a rising power, aiming at building its own order and sphere of influence, china has been engaging extensively in economic and social penetration of other countries. for instance, china banned rare earth metals exports to japan and curtailed the import of japanese autos due to the territory disputes regarding the senkaku/diaoyu island in the east china sea. china, as noted, also banned banana imports from the philippines to coerce the philippines to concede in the south china sea dispute. more important, economic globalization, the development of supply chains, and breakthroughs of network technology have jointly transformed and updated china's coercive capabilities. some liberal scholars argue that global networks create mutual dependence that decrease states' incentives to engage in conflict or coercion. however, as political scientists henry farrell at george washington university and abraham l. newman at georgetown university show, global connectivity actually creates new opportunities for great powers to coerce, manipulate, and penetrate. like hirschman's emphasis on power asymmetry in economic interdependence, farrell and newman also find that modern globalization results in asymmetrical networks, in which some states are far more connected than others. those states become the "hubs" of the global networks and have the capabilities to exploit "weaponized interdependence." specifically, those great powers can utilize their hub positions to gather information or cut off financial and information flows, discover and exploit vulnerabilities, compel policy change, and deter unwanted actions. sharp power and social penetration. financial power, hub positions in the global exchange networks, and information supply chains also enable authoritarian regimes to engage in comprehensive social penetration and manipulation of other societies. christopher walker and jessica ludwig of the national endowment for democracy analyze such phenomena through a lens of "sharp power," defined as authoritarian influence efforts to "pierce, penetrate, or perforate the information environments and societies in the targeted countries." to delegitimize democracies and other universal human-rights regimes, authoritarian regimes seek to incite and amplify existing divisions in democratic societies by manipulating or faking the information that reaches them. they also use financial incentives to induce media or civil societies in democracies to censor opinions that may be critical of those authoritarian regimes. finally, they employ new digital technologies to spread false and divisive discourse. authoritarian regimes usually exercise their sharp power through four types of social exchanges: cultural exchange programs, academic/think tank cooperation, media, and publishing. for example, china established a global network of confucius institutes all over the world to host cultural, educational, and academic exchange programs. each year, china also hosts several all-expenses-paid media and think tank conferences and exchanges with journalists and scholars worldwide. those programs and conferences, no matter how diversified they are, share one thing in common: censorship. program staff usually seek to block discussions on sensitive topics, such as taiwan, tibet, uyghurs, or other human rights issues in china. criticisms are discouraged, especially those that challenge the legitimacy of the chinese communist party (ccp). participants are expected to promote a positive image of china, as well as to praise china's social, economic, and cultural model and its achievements. of course, liberal hegemons or other democratic great powers also regularly promote their culture and political values worldwide. joseph nye uses "soft power" to describe liberal powers' pursuit of and competition for international attractiveness, legitimacy, and credibility. however, there are two qualitatively different characteristics between soft power and sharp power. first, as nye indicates, soft power rests in the ability of persuasion and voluntarism: you persuade your target to voluntarily follow your request with legitimate values or reasons. sharp power, in contrast, fundamentally rejects voluntarism. sharp power relies on the deceptive use of information and covert operations to mislead the target. in other words, sharp power is actually a type of coercive power because it eliminates the target's voluntary choices by manipulating ideas, political perceptions, electoral processes, and so on. second, openness is the prerequisite for developing soft power, while sharp power is based on opacity, censorship, and barriers to free flows of information. ultimately, soft power hinges on legitimacy, and no one can sustain legitimacy without transparency. a country is likely to lose its international legitimacy, as well as soft power, if it continues to rely on covert operations or secret diplomacy, or if its actions are opaque or have a hidden agenda. in contrast, opacity facilitates manipulation through disinformation and is thus conducive to sharp power. liberal democracies historically countered sharp power by promoting open information and transparency of state behaviors. however, information and communication technologies have created the opportunities for authoritarian regimes to exploit the openness and interdependence of global networks. today, authoritarian regimes like russia and china regularly spread fake news worldwide to sabotage democratic societies while raising barriers to fact-checking. they use international propaganda machines and cyber techniques to dump disinformation externally so as to crowd out the global information markets and drive out other news providers or media companies. at the same time, they further tighten domestic censorship. china, for instance, has launched several censorship programs, like the "great firewall" and "great cannon" among others, which guarantee that the chinese state-own news media can monopolize its domestic marketplace of information (ideas, news, knowledge, etc.). one central goal behind the use of sharp power is to delegitimize democracies, as well as to decrease democratic soft power. dictatorships manipulate the information and destabilize democratic societies in order to show that democratic institutions and values, such as freedom and universal human rights, are no better than authoritarian ones in solving domestic disputes. furthermore, they combine sharp power with economic statecraft to propagate the argument that authoritarianism (dictators often calling it "strong nation") could be an alternative model, perhaps a better one, for development. of course, authoritarian regimes may face international backlash once their sharp power operations are disclosed. however, dictators can still benefit from sharp power because it could help consolidate authoritarian grips on domestic affairs. because dictatorships impose censorship, they can block external information and shape domestic opinions about international responses. dictators may even take advantage of international pushback to stimulate domestic resentment and patriotism. in essence, the priority is to strengthen authoritarian stability by using sharp power to penetrate other societies. china has exploited global networks in a number of ways. first, as hirschman reminded us, great powers regularly seek to convert their economic might into political leverage around the world. china is no exception. with the development of global and regional connectivity, china has used its financial muscles to gain control over major natural resources and strategic locations and to influence other states' stances in disputes. china has provided a substantial amount of aid to african countries to harden its grasp on natural resources. beijing has also launched comprehensive programs of financial statecraft, known as belt and road initiatives (bri), to establish its sphere of influence in the indo-pacific region and even the whole of eurasia. china's financial prowess successfully has swayed some states' stances in many regional disputes. philippine president rodrigo duterte's recent concession on the south china sea dispute is one notable example. another salient case is china's successful effort to induce the solomon islands to end its diplomatic relationship with taiwan. second, the fundamental goal for the chinese leadership is to create a world that is safe for china's authoritarian regime. such an objective could be achieved if there are more non-democratic regimes around the world, or more countries adopting the "china model." therefore, china does not only seek to develop its repressive capacities, but also it tries to export its censorship regime-encouraging other authoritarian regimes to censor and silence domestic dissidents with the technologies and programs it supplies. china's strategy is twofold: first, it has exploited global supply chains and cross-border networks to upgrade its infrastructural power for censorship and monitoring domestic citizens. for example, china has engaged in intellectual property theft worldwide and cyber espionage to increase its information and communication technologies. it has also provided various governmental supports to develop huawei, china's largest telecommunications company and chinese "national champion" of the g industry. huawei's success and control over g network technologies have enabled the chinese government to collect and store the data of almost every chinese citizen. the government also used similar industrial policies to develop hikvision digital technology and dahua technology, chinese manufacturers and the world's two largest suppliers of video surveillance products. the monitoring capacity provided by chinese surveillance camera companies, together with huawei's big data technology, strengthen china's policing capacity and the communist party's censorship. the second fold of china's strategy is to export its censorship regime to other countries as well as surveillance hardware and data-analytics tools. china has engaged in social penetration into other societies and wielded its sharp power globally to justify the china model. for example, beijing is cultivating media elites and government ministers around the world to create a network of countries that will follow its lead on internet policy. chinese officials have held many all-expensespaid trainings, workshops, seminars, and conferences with representatives from other countries. during those events, china regularly propagates that the chinese model of censorship is helpful in combating terrorism and fake news, monitoring public opinion, china/diplomacy/article/ /us-cancels-solomon-islands-meeting-after-disappointmentit. and ensuring cyber security. several countries introduced cyber-security laws that closely mimic china's own version after their official participated in those events. finally, and much more concerning, the chinese state apparatus has been developing its "information troops" to silence or deter dissidents as well as to enforce pro-china views at home and abroad. the great majority of these troops-called by some as the " -cent army"-may not actually be part of the security apparatus, but independent operators including student volunteers at universities, communist youth league members, and government bureaucrats. according to political scientists gary king at harvard, jennifer pan at stanford, and margaret e. roberts at university of california san diego, the chinese state apparatus is involved in faking several hundred million social media accounts and posts. the chinese information troops often use social media to launch campaigns against voices or opinions that criticize the chinese government or challenge the legitimacy of the ccp. the troops constantly use fake news or specious arguments to manipulate public opinion. with help from chinese government censorship, they can easily silence dissents and "manufacture" some public consensus. then, backed by this manufactured consensus, the chinese government is able to resort to coercion against the dissenters. in january , chou tzu-yu, a taiwanese singer in the korean pop band twice, performed while holding a taiwanese national flag on a korean tv show. the chinese government and information troops directed a campaign that led to a ban on chou's presence on almost every tv show in china. and beijing demanded that chou's korean management company, jyp, refund the loss of those shows. eventually, chow was forced to bow deeply and tearfully read a scripted apology that accepted "one china" in the media. in august , china ordered the hong kongbased airline cathay pacific to suspend any staff that supports pro-democracy protests in hong kong. perhaps even more telling was china's ban on the broadcasts of the preseason games of the u.s. national basketball association (nba) due to a tweet by houston rockets general manager daryl morey that appeared to support the hong kong pro-democracy movements. although morey was soon forced to delete the tweet, the chinese government still demanded that the company remove morey from his post. when nba commissioner adam silver insisted that freedom of expression s i | is a principle not to be compromised, the chinese government and information troops launched a series of boycott campaigns against the nba. in sum, economic statecraft and social penetration have become china's common practices to further its national goal. taiwan, which is highly dependent on china for its economy, is on the frontline of china's weaponized interdependence. as indicated earlier, the reunification of taiwan is china's self-defined core interest. hence, china has been engaging in economic and social penetration into taiwanese society. china's aim toward taiwan is threefold: increasing taiwan's dependence to cultivate pro-china factions in taiwanese society, constraining taiwan's pursuit of independence and democratic values, and forcing taiwan to gradually accept china's preferred version of "one-country, two-systems." china has been taiwan's largest trading partner. in , china accounted for . percent of taiwan's foreign trade (while taiwan only accounted for about percent of china's foreign trade). china continues to be the largest destination of taiwanese foreign direct investment ( . percent in ) and the top destination for taiwanese heading overseas to work. in , , taiwanese worked in china, (including hong kong and macao), accounting for . percent of all taiwanese nationals working overseas. china is the largest single source of visitors to taiwan. in (january-october), percent of total tourists visiting taiwan were chinese citizens. these statistics indicate that the economic and social network interdependence between china and taiwan is highly asymmetrical. decades ago, hirschman depicted how nazi germany used industrial policies, market size, and technology to shape eastern and southeastern european neighbors' foreign trade relations, making them substantially dependent on the german market. those efforts contributed to the rise of germany's power over them before and during wwii. today, china is poised to establish its own sphere of influence over taiwan. just as great powers did in history, china has been engaging in the " m" approach of economic statecraft and social penetration against taiwan: money, manpower exchange, misinformation, mooching (cultivating compradors), and magnifying (propagating the "chinese dream"). roman philosopher marcus tullius cicero ( bc- bc) argued: "the sinews of war are infinite money." even during peacetime, money is one of the most crucial foundations for national power and statecraft. regarding china's economic and social statecraft, money could be broadly understood as any forms of positive inducements-providing quid pro quos to anyone for their loyalty and behaviors consistent with china's national interest. those quid pro quos include, but are not limited to, economic and societal benefits, such as granting market/profit shares, licensing, subsidies, protections, and various forms of privileges. in general, china utilizes its monetary power in three ways: positive quid pro quos, negative sanctions (or threaten to launch negative sanctions), and penetration of taiwanese companies for future collusion. positive quid pro quos. there are various examples of china using quid pro quos to gain leverage in taiwan. one of the most significant examples was the economic cooperation framework agreement (ecfa), a preferential trade agreement signed in between china and taiwan. through ecfa, china unilaterally lowered tariffs on many taiwanese agriculture goods and others. here, we find a historical parallel. in the s, as hirschman pointed out, germany supported the agricultural economies of southeastern europe by not only paying them higher prices, but also by promising them stability in both price and volume of their exports. therefore, germany cultivated vested interests in those countries, and tied the interests of existing powerful groups in their societies to relations with germany. likewise, china's quid pro quos have created powerful vested interests in taiwanese society and misperceptions about taiwan's economy and governance. for example, although the data shows that in recent years taiwan's economic situation has been relatively stable, compared with most of the countries in the region, as well as globally, still a substantial portion of taiwanese population think that the ruling party democratic progressive party (ddp) and incumbent president tsai ing-wen did not handle the economy or cross-strait relations well. although ecfa created powerful vested interests in supporting china's influence, it also provoked taiwanese societal discontent with the hollowing-out effect on taiwan provide for "national treatment" to induce taiwanese youth, enterprises, startup entrepreneurs, and blue-and white-collar workers in many sectors. taiwan-funded companies may be qualified to take part in china's key industries, such as major technological equipment, g networks, and civil aviation. in addition, the measures allow taiwanese athletes to be treated as chinese nationals when joining professional sport leagues in china. china's economic statecraft has gained success in a number of cases. in december , days after the dpp's landslide defeat in the local elections, wu paochun, an international award-winning taiwanese baker, announced that he was going to open branches of his bakery in china. however, in order to appease chinese netizens, wu issued a statement saying that he was born in "taiwan, china" and is "proud to be chinese." wu insisted that "two sides of the strait are one family" and is willing to promote economic exchanges and trade across the taiwan strait. wu also hoped that he could participate in the "measures to promote cross-strait economic and cultural ties" released by china's taiwan affairs office of the state council. china's tactics are especially effective in the entertainment industry. several taiwanese celebrities currently working in china have made supportive statements consistent with china' interests, even including the sovereignty issue. in , after the permanent court of arbitration negated china's "nine-dash line" claims to the south china sea, many chinese celebrities started to post a map of the territory that china officially claims, including the nine-dash line. the image also bears a slogan: "china: we cannot lose a single inch [of territory]" and "china's territorial sovereignty doesn't need others to arbitrate." in , then, after a taiwanese director made an independence-leaning, pro-democracy award speech at the golden horse film festival and awards (the chinese-speaking world's version of "oscars"), beijing immediately censored the broadcast of the award ceremony. this time, many taiwanese celebrities working in china immediately posted or re-tweeted that image and the slogan: "china: we cannot lose a single inch" even though taiwan has different claims on its own sovereign territory and the south china sea dispute. negative sanctions or threatening. negative sanctions are common in china's toolbox of economic statecraft. once china successfully cultivates asymmetrical networks with other states, or private actors, and makes them highly dependent on china, beijing becomes more capable of coercing them by cutting (or threatening to cut) the money flows. for example, the chinese recently suspended a program that allowed individual tourists from chinese cities to travel to taiwan, citing the current state of relations between the two sides. the scheme had been in place since under the more china-friendly administration of former president ma ying-jeou. the suspension is commonly interpreted as china's effort to dampen local support for the dpp by cooling the tourism industry in taiwan. another salient example was the "yifang fruit tea event." yifang fruit tea ( , yī fāng shuǐ shuǐ guǒ chá) is one of the famous taiwanese tea brands that has opened many shops around asia. in august , when the pro-democracy protests in hong kong escalated, one of yifang fruit tea shops in hong kong closed for a day and put up a sign that read in chinese: "stand together with hong kongers." chinese netizens were furious because it seemed like yifang fruit tea was backing pro-democracy protests in hong kong. they called for a boycott on yifang, which soon spread to other taiwanese bubble tea brands, including gong cha, heytea, coco, and a little tea. days after the boycott, yifang fruit tea issued a statement on social media in china, saying that yifang firmly supports "one country, two systems" and opposes protests and strikes in hong kong. china also constantly enacts negative sanctions in the entertainment industry. in august , china's film regulator announced that it was prohibiting the chinese movie industry from participating in taiwan's golden horse awards. in addition, a popular taiwanese youtuber lost his business in china after a video of him interviewing taiwan's president went viral. in the video, potter king, a taiwanese internet celebrity with a significant following on both sides of the taiwan strait, addressed taiwan's leader, tsai ing-wen, as "president." king's chinese distributor immediately demanded that he to take down the interview from taiwanese social media. his chinese social media accounts were also seized by the chinese distributor, who removed the video from chinese social media. later, the chinese distributor released a statement indicating that potter king's contract had been terminated. it described king's language and actions as "inappropriate," and "it strongly rebukes any actions which undermines china's dignity and sovereignty. it firmly insists 'one china' principle." china also seeks to use licensing or customs inspection to coerce taiwanese companies to accept the "one-china principle." for example, taiwanese companies need to label their goods as made in "taiwan area, china," instead of "made in taiwan" or "made in taiwan, r.o.c." when they export to china. if they do not comply, then they may face extra duties or longer inspection time. in some cases, customs agencies in china destroyed imported taiwanese products that did not have the newly required "taiwan area, china" label. illegal buyout and forced collusion. lastly, china is also launching two sophisticated monetary statecrafts to penetrate individual taiwanese companies as well as the whole industries. chinese state-owned or state-backed enterprises constantly use their enormous financial resources to lure taiwanese companies, especially those with crucial know-how, to cooperate and jointly develop business. for example, in , tsinghua unigroup ltd, a chinese state-owned technology conglomerate, planned to spend billions to acquire stakes in three taiwanese semiconductor companies. the three targets, silicon precision industries co. (spic), powertech technology inc., and chipmos technologies inc., are all leading chip packing and testing companies in the global arena. the case was controversial because tsinghua unigroup's parent company, tsinghua holding, is considered deeply connected with the chinese communist party. tsinghua holding's former communist party secretary, hu haifeng, is the son of hu jintao, the predecessor of xi jinping. tsinghua unigroup used to have strong government support; in fact, its acquisitions were far beyond its yearly revenue. because the acquisition of tsinghua unigroup raised concerns about market monopoly and national security, the taiwanese regulatory agency reviewed it carefully. in the end, the three investment plans of tsinghua unigroup failed. however, there are many cases where chinese state capital tried to enter taiwan through a third location (either hong kong or singapore) in order to circumvent taiwanese regulations. more concerning still is china's collusion strategy. once chinese state-owned enterprises (soes) acquire controlling shares of a taiwanese company, these enterprises not only want to grab the crucial know-how/technologies of that company, but they also try to leverage the newly acquired company as part of broader economic statecraft. one notable example was a case of china's economic espionage, in which a taiwanese company was charged with helping a chinese soe steal a u.s. company's intellectual property. according to the u.s. department of justice's indictment, prior to the intellectual property theft, fujian jinhua integrated circuit, co., ltd. ("fujian jinhua"), a chinese soe, did not possess dram technology. then, fujian jinhua sought help from a taiwanese individual, chen zhengkun, who previously worked for micron (the u.s. company) and became the president of a micron subsidiary in taiwan responsible for manufacturing micron's dram chips. chen resigned from micron in july and immediately began working at united microelectronics corporation ("umc"), a taiwan semiconductor foundry. while at umc, chen arranged a cooperation agreement between umc and fujian jinhua; with funding from fujian jinhua and the chinese government, umc would transfer dram technology to fujian jinhua. chen later became the president of fujian jinhua and was responsible for its dram production facility. while at umc, chen recruited taiwanese employees from micron to join him at umc. those taiwanese employees stole and brought to umc several micron trade secrets related to the design and manufacture of dram. manpower exchange is another part of china's economic and social statecraft. china is not the first great power to use its networks of manpower to cultivate external influences. in hirschman's study, anecdotal evidence shows the export of german trained and skilled labor contributed to germany's penetration into foreign countries. china is practicing similar tactics. what makes china's manpower strategy so special is its size, and how comprehensive and sophisticated china's manpower networks have become. the flows of manpower as well as other types of social exchanges create opportunities for china to not only develop the united front in the taiwanese society, but also to breed taiwanese affinity with the ccp. the chinese state apparatus has been using multiple manpower channels to make direct contacts with local people and grant benefits to them. china's statecraft used to focus on the "three middles and the youth"-the youth, small and medium enterprises, middle-and low-income classes, and the population in the middle and southern taiwan, who are traditionally considered more pro-independent. in , yu zhengsheng, the chairman of the chinese people's political consultative conference (cppcc) and member of the politburo standing committee, further unveiled that china's economic and social statecraft is going to target "one generation and on stratum" in taiwan-the younger generation and the grassroots. china has launched its social penetration operations through those channels, and two are most influential: religious networks established by local temples and quasiillegal organizations, and various "cross-strait exchange groups." traditionally, china used to manipulate these two channels to penetrate the whole taiwanese society, including both the younger generation and the grassroots. in recent years, religious networks have become china's main instrument toward the grassroots because of the political-societal role local temples play in the communities. as for the younger generation, china has become more inclined to rely on cross-strait exchange groups to tempt the taiwanese youth with travel, studying, and job opportunities. religious networks, local temples, and quasi-illegal organizations. in taiwan, temples play an important role in local lives and communities. because of their huge cash flows and unsupervised finances, temples are the foundation of taiwan's underground economy. temples also serve as a place for regular gathering and information sharing within the communities. finally, temples usually function as local charities in taiwan and may provide emergency support in natural disasters (though their roles in this regard are limited). therefore, temples tend to have important political influence over local communities and a capacity for political mobilization. because a large number of people on both sides of the taiwan strait share similar religions, the chinese state apparatus has noticed the potential to use temples and religious exchanges to win local people's heart. accordingly, the chinese state apparatus has been actively seeking local agents' help to develop cross-strait religious networks with temples in taiwan. one famous agent is the chinese unification promotion party, also known as the unionist party. the unionist party was founded in by the "white wolf" chang an-lo, formerly a key member of the bamboo union, a gang accused of engaging in organized crime. the unionist party is controversial not only because of its strong pro-unification stance, but also due to its aggressive tactics. for example, it provoked violence and attacked pro-independence demonstrators in the "sing! china" event at national taiwan university. in addition, its members were constantly seen holding chinese flags outside the taipei skyscraper to confront falun gong ( , fǎ lun gōng) members. moreover, in , during a rally in taiwan supporting pro-democracy movements in hong kong, the unionist party members threw red paint at the participants. furthermore, the unionist party held several conferences and activities in taiwan to promote the idea of unification by any means, including brute force. the unionist party also uses its networks to help chinese people more easily enter taiwan to conduct political propaganda. for example, the unionist party invited li yi, a chinese scholar, who once argued for the necessity of using force for unification, to deliver a political speech in a pro-unification conference although li's visa was only for tourism. in addition, chang wei, son of chang an-lo, runs the huaxia dadi travel service co, a shadow travel agency for chinese tourists. huaxia dadi and other shadow travel agencies have used "fake exchange proposals" to secretly and illegally help more than , chinese people enter taiwan, including chinese civil servants. according to one report in commonwealth magazine, there are three pillars of the unionist party: gangs (or former gangs), temples, and overseas taiwanese businesses. the unionist party and temples have a close cooperative relationship, and some have secured important positions in temple groups. a notable example is lin kuo-ching, a former gang member, who is now a member of the unionist party's central committee. lin serves as the honorary chairman of several temples, and has excellent relations with the taiwan mazu fellowship run by yen ching-piao. moreover, because smaller temples usually find it hard to establish channels for interaction with temples in china, they turn to the unionist party for help. in exchange, they give party members lucrative contracts for the temple's processions and rituals. now, several small and medium private temples around taiwan are said to have links with the unionist party. in sum, the unionist party, other pro-unification organizations, and taiwanese local temples jointly have created a powerful network of local political mobilization. such a network has become a major channel for the chinese state apparatus to target the grass roots in taiwan and cultivate local communities' affinity with china and the ccp. cross-strait exchange groups. the cross-strait exchange groups are another crucial element of china's social penetration efforts. for many years, the chinese government has used semi-official or puppet organizations to increase and deepen economic, social, and cultural ties between taiwan and china. the aim of those groups has been to cultivate a shared "pan-chinese" identity and to create vested interests in unification. a common strategy for those exchange groups is free tours to specific places in china. such "tours" are planned by the exchange groups, and travel expenses and accommodation are fully covered. during each tour, taiwanese participants are exposed to political propaganda. on occasion, ccp officials deliver keynote speeches. taiwanese participants are also likely to receive some benefits (or promise of benefits). last, personal networks between taiwanese and chinese are established during the interactions. those tours could increase the likelihood that participants rejoin similar tours in the future. with increased participation, powerful bonds are likely to develop between the taiwanese participants and china. those bonds may become useful tools for the chinese government to shape the identity and interest of the taiwanese participants, making them more willing to accept china's influence. previously, those exchange groups mostly focused on taiwanese adults or the elderly. recently, they have shifted their target to taiwanese youth. according to the data, every summer, more than , taiwanese students participate in such china tours. there are usually five kinds of tours. the first is theme workshops or forums. the themes include: leadership, entrepreneurship, development, technology, and chinese history and culture. such tours tend to be organized by top chinese universities and usually contain political propaganda. the second kind of tour is corporate internships. participants have the opportunity for internships in different chinese companies. their travel expenses and accommodation are covered, and they can earn stipends. participants can develop their personal networks. following the internships, participants also have chances to become full-time employees. this kind of tour can cultivate participants' material interest in china and has the potential to function as positive quid pro quos. the third kind of tours is natural and historic sites, and business parks. this kind of tour is usually the presentation of china's soft power. the fourth type of tour is academic conferences and expert workshops. because there are many high-ranking chinese universities, and those universities have more resources to hire renowned professors, this kind of tours can attract taiwanese students seeking more educational opportunities and future employment. finally, there are "art and sport exchange tours." to some extent, this kind of tour functions as the "ping pong diplomacy" between the united states and china from the s. however, such tours have powerful potential as economic and social statecraft because they target even younger generations, such as teenagers, or the athletes, who face an insecure job market in taiwan. china also resorts to sharp power to misinform the taiwanese public, manipulate the society, and sabotage taiwan democracy. china's manipulation in taiwan's politics has been carried out through different channels over years. with the development of cyber technologies, china has also been making greater effort in nurturing pro-communist media and strengthening its capability to manipulate social media in taiwan. in january , when tsai ing-wen won the presidential election, members of "diba," a forum with more than million followers on china's largest search engine baidu, called upon chinese web-users to flood prominent taiwan-related facebook pages with anti-taiwan independence comments. within hours, there were , negative comments on tsai's facebook page. "diba expedition"-an abbreviated description of the campaign-became a top trending search on china's social media weibo. another example was the rise of han kuo-yu, the kuomintang (kmt) party's presidential candidate in and mayor of kaohsiung city. han was a largely unknown name until late summer , barely four months before the mayoral election. however, han started his meteoric rise through the polls. he eventually won a landslide victory in the critical election. many people attributed han's ascendancy to his personal charisma and popularity on social media. for example, han kuo-yu's official facebook account had half a million followers at the end of the campaign. however, a careful analysis shows that china's information manipulation may have contributed to han's victory. as paul huang points out, many of han's facebook supporting groups were created, managed, and nurtured by what looks very much like a professional cyber group from china. those groups helped mobilize the support for han through many means, including using fake news to manipulate the public attitude. china's manipulation tactics and espionage are also common in taiwanese academia. an anonymous scholar from national sun yat-sen university pointed out that since , unidentified hackers have silently accessed and checked the email of more than professors of political science and international relations through several fake accounts posing as senior school administrators. the intruders' ip address has been traced back to china, hong kong, and the united states. this year, the hackers' ip addresses were highly concentrated in hong kong and were suspected of being a domain address generated by using a virtual private network (vpn). this suspicion indicates that china may have extended its cyber espionage network into the taiwanese academia and universities to increase political control by monitoring the behavior of teachers and students. another method for china to penetrate taiwan's society and politics is "mooching." the purpose of mooching is to cultivate local political agents loyal to the ccp, and to use them to undercut the capacity and authority of taiwanese government. to some extent, the strategy is similar to colonial authorities' policy toward local compradors. the mooching approach resembles the manpower exchange approach. for example, both approaches include approaching/inviting taiwan's opinion leaders, local politicians, community leaders, and key figures, such as retired ministers, exmilitary generals, religious leaders, school principals, and teachers, as well as young students to take part in cross-strait forums and various exchange programs organized by china's public and private sectors. nevertheless, these two approaches are different. first, they rely on different ways to govern cross-strait ties. the manpower exchange approach focuses on building institutionalized channels to conduct routine cross-strait interactions, while the mooching approach emphasizes developing informal networks to deal with ad hoc tasks. second, each approach has a distinct strategic goal. the manpower exchange approach seeks to shape taiwanese general public opinion toward china and the ccp, and to foster a group of constituents that can influence taiwanese politics in china's favor. in contrast, the mooching approach aims for cultivating specific pro-china agents to conduct ad hoc cross-strait affairs. a salient example is the recent taiwanese evacuation from wuhan due to the coronavirus. after the outbreak of the novel coronavirus (also commonly known as the wuhan coronavirus) in china, taiwan's government kept requesting that beijing permit the evacuation of taiwanese citizens from wuhan. however, the chinese government did not respond to taiwan's request because china stopped official communications with the incumbent government led by president tsai ing-wen since . china also continues to block taiwan's attendance at the world health organization, constricting the taiwanese government's ability to receive timely information about the coronavirus situation. beijing eventually allowed an evacuation flight due to the worsening situation. however, media reported that the chinese officials only collaborated with pro-china taiwanese businesspersons and elites when drafting flight manifests, rather than allowing taiwan's government to directly handle the evacuation. the mooching method is also widely adopted by china's local governments, enterprises, and associations when they approach young taiwanese. for example, china's universities provide young taiwanese doctorates with assistant the author interviewed a community leader in yilan county on his opinion regarding cross-strait local community interaction. he argued, "china is developing democracy at the grassroots level. wealthy and strong community organizations are important to improve their quality of life. therefore, community representatives came to taiwan to learn about the development and reinvigoration of local community and are aimed at establishing close ties between grassroots communities in china and taiwan. from their perspective, it is to facilitate natural social integration of both sides. nevertheless, with our successful experience, they shall and will thank taiwan and maintain good relationship with us." interview with a local community leader in yilan county, dec. , . huang tzu-ti, "x-defense minister of taiwan says beijing approached him," taiwan news, dec. , , https://www.taiwannews.com.tw/en/news/ . "coronavirus: beijing allows taipei to evacuate taiwanese in wuhan," the straits times, feb , , https://www.straitstimes.com/asia/east-asia/beijing-allows-taipei-to-evacuatetaiwanese-in-wuhan; and nick aspinwall, "taiwan's coronavirus response hits obstacles set by chinese government?," the diplomat, feb. , , https://thediplomat.com/ / /taiwans-coronavirus-response-hits-obstacles-set-bychinese-government/. professorships. local governments offer young entrepreneurs with funding for startups, working spaces, law services (ex. company registration service), and other business incentives. some professional associations even provide young taiwanese professionals with certificates related to their future careers. for example, young tea farmers in central taiwan are encouraged to take china's version of certification in tea art. it is easier for those with china's professional qualification certificates to seek jobs in china and to promote taiwanese tea products in chinese market. china's final approach to penetrate taiwanese society is "magnifying." similar to the misinformation approach, magnifying is also a strategy of using media to create disinformation to manipulate taiwanese public opinion, a case of china's sharp power. however, the two approaches have different missions and tactics. the goal of the misinformation approach is to delegitimize taiwan's democratic institutions and values. hence, misinformation regularly relies on fake news to amplify existing divisions, instigate social conflicts, trigger political instability, and sabotage public trust and confidence in the taiwanese government. in contrast, magnifying is designed to propagate the china model, glorify the "chinese dream," and preach the necessity of reunification of taiwan and china. therefore, the magnifying approach adopts media propaganda that exalts the success of china's development, highlights china's cultural significance, praises china's contribution to the world, and advocates the benefit and the inevitability of joining china's sphere of influence. in recent years, the chinese state apparatus and pro-china forces have targeted the southern localities of taiwan by using various media channels, such as traditional radio stations and new social media. the local radio stations in the central and southern part of taiwan traditionally were the primary local sources of everyday information in support of the pro-taiwan independence sentiments, and the audience is regarded as deep-green supporters and anti-china hot-liners. in taiwan, the key member of chinese unification promotion party hosts radio programs in the southern cities in conjunction with new social media, such as live streaming facebook fans page, to convey the pro-china ideology and disinformation to local people. the brainwashing information includes praising china's political economic development and industrial policy under the leadership of xi jinping, promoting the success of the bri globally, and advocating the cross-strait social and economic integration. some programs even argued that the people's liberation army, china's warships, missiles, and fighters circumnavigating taiwan were to defend taiwan against terrorism or other countries, including the united states and japan. these programs are to formulate a new pro-china social echo chamber in the deep-green localities of taiwan. cross-strait relations between china and taiwan used to maintain a fragile balance. however, since the global financial crisis of - , china has become more assertive in challenging international norms, pursuing national rejuvenation, and wielding its power globally. china's threatening behaviors have pushed the relationship between taipei and beijing toward the brink of crisis. in order to counter china's threat, taiwan needs to be vigilant and take necessary measures. first, taiwan must pay attention to china's economic and social penetration and cultivate the general will and commitment to defending its democracy and sovereignty. as hirschman underscored, when facing great power's threat of domination, if a small country pays greater attention to the asymmetrical relationship, and maintains a stronger commitment to defending its autonomy, the "disparity of commitment" could generate room for the smaller country to maneuver to achieve greater autonomy. taiwan's democracy is the best antibody against china's penetration. the taiwanese government as well as taiwanese people must be vigilant against china's statecraft. taiwan must be deeply committed to its democratic development and institutions. recently, taiwan passed a new cybersecurity law and enacted new penalties on fake news. the government and civil society also cooperate to form fact-checking mechanisms to curb fake news and disinformation. taiwan is initiating an "antiinfiltration law" to counter external interference in domestic affairs, such as elections and legislations. those measures are essential to assure taiwan's democratic resilience against china's threat and malicious penetration. in addition, taiwan must continue seeking, building, and strengthening relationships with democratic, like-minded allies. china's economic and social leverage arise from its hub position in global networks, in which many other countries are asymmetrically dependent on china. of course, chinese markets, resources, and civil societies are valuable assets for world development, and there are always opportunities for cooperation with china. while, it is unnecessary to cut off economic interactions with china, taiwan should pursue a diversification strategy. taiwan has sought to contribute to one cluster among the contending regional approaches in the indo-pacific region, including the u.s.-led free and open indo-pacific (foip) strategy, the ira, social media and political polarization in the united states china's unilateral sanctions weaponized interdependence: how global economic networks shape state coercion what is 'sharp power'? how sharp power threatens soft power: the right and wrong ways to respond to authoritarian influence the rise of digital authoritarianism fake news: national security in the post-truth era how the chinese government fabricates social media posts for strategic distraction, not engaged argument a -year-old pop star was forced to apologize to china for waving taiwan's flag taiwan rebukes beijing's new measures for cross-strait exchanges taipei times the social media 'war' over the south china sea you can speak whatever you want in the golden horse film festival:' from 'taiwan as an independent country' to 'china: we cannot lose a single inch china bans citizens from traveling to taiwan as individual tourists storm in a bubble teacup over taiwan firm's support for hong kong protesters absence of china a 'loss' at chinese-language 'oscars' in taiwan taiwan youtuber loses china business over tsai interview goods manufactured in taiwan and exported to china are required to be labeled 'made in taiwan, china,' source tells china's tsinghua unigroup to invest $ billion via world's biggest private placement chinese cyber-operatives boosted taiwan's insurgent candidate hackers accessed to and monitored the email accounts of political science professors of national sun yat-sen university for three years most of the participants were strongly encouraged to show their support for chinese nationalism, recognize the traditional cultural roots as the basis for the unification of the two sides of the taiwan straits the opinion leaders, including scholars, experts, and retired military officers, were invited to participate in china's state-run tv programs and expressed their support for the chinese government or the unification of the two sides of the taiwan straits, which led the chinese people to mistakenly believe that this was the mainstream opinion of taiwanese society. see, chung li-hua interview with a young tea farmer who was encouraged to take the qualification exam of tea artist in china chang mong-tsung's facebook page china provides no solution for taiwan japan's indo-pacific vision, and india's act east policy to reinforce its relationships with the like-minded countries and other democracies in the region taiwan's nsp not only seeks to build trade and investment linkages, but also pursues mutually beneficial social bonds through people-to-people centered networks since xi jinping consolidated his grip on power, the risk of china abusing its power has increased dramatically. today, the chinese government is imposing stringent rules on domestic citizens, including detention camps in xinjiang and the social credit/surveillance system for all citizens. it also has become much more aggressive in challenging democratic values and universal human rights globally. china has been using its financial and technological power to export censorship and promote authoritarianism to other countries. it has leveraged its position in global networks to penetrate other democratic societies to undermine universal values including the freedom of expression. beijing's social penetration and economic coercion pose severe challenges for democracies unpacking taiwan's presence in southeast asia: the international socialization of the new southbound policy a taiwanese vision for a free and open indo -pacific region key: cord- -wisaamn authors: law, chi-kin; leung, candi mc title: temporal patterns of charcoal burning suicides among the working age population in hong kong sar: the influence of economic activity status and sex date: - - journal: bmc public health doi: . / - - - sha: doc_id: cord_uid: wisaamn background: charcoal burning in a sealed room has recently emerged as the second most common suicide means in hong kong, causing approximately deaths each year. as charcoal burning suicide victims have a unique sociodemographic profile (i.e., predominantly economically active men), they may commit suicide at specific times. however, little is known about the temporal patterns of charcoal burning suicides. methods: suicide data from to on victims of usual working age ( – ) were obtained from the registered death files of the census and statistics department of hong kong. a total of cases of charcoal burning suicide were analyzed using a two-step procedure, which first examined the temporal asymmetries in the incidence of suicide, and second investigated whether these asymmetries were influenced by sex and/or economic activity status. poisson regression analyses were employed to model the monthly and daily patterns of suicide by economic activity status and sex. results: our findings revealed pronounced monthly and daily temporal variations in the pattern of charcoal burning suicides in hong kong. consistent with previous findings on overall suicide deaths, there was an overall spring peak in april, and monday was the common high risk day for all groups. although sex determined the pattern of variation in charcoal burning suicides, the magnitude of the variation was influenced by the economic activity status of the victims. conclusion: the traditional classification of suicide methods as either violent or nonviolent tends to elide the temporal variations of specific methods. the interaction between sex and economic activity status observed in the present study indicates that sex should be taken into consideration when investigating the influence of economic activity status on temporal variations of suicide. this finding also suggests that suicide prevention efforts should be both time- and subgroup-specific. temporal variation in suicide deaths is an important topic in suicide research worldwide. identifying the most probable timing of suicidiality will help to improve intervention and prevention efforts. charcoal burning in a sealed room has recently emerged as the second most common suicide method in hong kong [ ] [ ] [ ] [ ] [ ] . being a relatively painless and inexpensive method, charcoal burning has rapidly increased the suicide rates in the past few years [ ] . however, no prior research has examined the temporal pattern of suicides by charcoal burning. previous studies consistently showed asymmetrical distributions of suicide deaths. for both sexes, major peaks were found in late spring or summer ("spring fever") [ ] [ ] [ ] [ ] [ ] [ ] , whereas a nadir was noted in december (winter) [ ] . compared with monthly patterns, the daily (referred to as "weekday" or "weekly" in the literature) pattern of suicides is relatively under-researched, particularly in the hong kong context. notwithstanding the limited number of studies, the findings on the daily pattern of suicides were similar to those observed in the related studies, with marked peaks on mondays and nadirs on weekends [ , ] . thus, charcoal burning suicides may also have temporal variations if they follow a similar pattern. however, being a non-violent suicide method, charcoal burning is often assumed to have no obvious temporal patterns. in some seasonality studies, suicides by violent methods (e.g. jumping and hanging) showed more marked temporal variations when compared with nonviolent suicides (e.g. poisoning) [ , , ] . this may suggest that charcoal burning suicides do not have obvious temporal variations in either monthly or daily distributions. accordingly, the recent surge in suicides by charcoal burning would lead to a smoothing of the temporal variations in suicide in hong kong. the unique sociodemographic profile of the victims of charcoal burning suicide suggests that they may tend to commit suicide at specific times. charcoal burning suicide victims were more likely to be economically active and over-indebted than other suicide victims [ ] . although economic activity status had no influence on the monthly pattern of overall suicide deaths [ ] , its exact impact on the temporal patterns of charcoal burning suicides is unclear. it is reasonable to assume that the employed victims were particularly vulnerable to the fear of job loss, which has been found to significantly predict depressive symptoms and suicide mortality [ , ] . as the weekend represents a potential break from the stresses experienced during the work week, it is possible that suicide rates are lower during the weekend than during the work week. employed victims may also experience a greater fear of job loss during seasonal layoff periods and thus may be more inclined to commit suicide. the unemployed may also have a higher suicide risk at specific times as a result of the stress of job searching. some researchers have noted that during weekends, the unemployed tended to spend more time on socializing activities and significantly less time on job searching [ ] . consequently, unemployed people may be more likely to commit suicide during the week, as they experience higher levels of stress in relation to job searching during this period of time [ ] . the unemployed may also be more anxious about finding a job during recruitment seasons. nonetheless, community-based research in this area is lacking. the influence of economic activity status on the daily and monthly patterns of charcoal burning suicides is yet to be examined. in addition to economic activity status, sex difference may also influence the temporal pattern of charcoal burning suicides. in previous studies, a bimodal distribution of monthly suicide deaths was observed in women but not in men [ , ] . sex also interacted with the suicide method on the temporal patterns of suicide [ , ] . as the victims of charcoal burning suicide were predominately economically active men [ , ] , an interaction between sex and economic activity status on the temporal pattern of charcoal burning suicides is possible. however, this is yet to be investigated. the present study aims to fill these gaps in the existing research by examining the temporal asymmetries in the monthly and daily distributions of charcoal burning suicides in hong kong. in particular, the study will examine the temporal variations of charcoal burning suicides in relation to the economic activity status and sex of victims of usual working age ( - ). the present study covers the period, from to . suicide data were obtained from the registered death files of the census and statistics department of hong kong. following the th revision of the international classification of diseases and related health problems (icd- ), reportable deaths with an external cause code ranging from x to x are classified as suicide [ ] . a total of suicide cases were reported during the overall study period, with cases ( . %) involving victims of usual working age . of these cases, . % ( cases) were charcoal burning suicides (x ). all of the recorded suicides included information on the age, sex, and economic activity status (working versus non-working) of the victim, and the date of death and method used. to analyze the monthly and daily patterns, the data were divided into months of a year and days of a week, respectively. to examine the amplitude of temporal variation in suicides and its statistical significance, multinomial poisson regression analyses were conducted by fitting the number of suicides for each month/day of the week with the corresponding time variable [ , ] . given that the size of the usual working age population in hong kong increased by % during the study period, from . million in to . million in , the poisson regression is a more appropriate method than the chi-square test, which assumes that there has been no significant change in the size of the population. the poisson regression can also adjust for changes in regard to sex and economic activity status within the population over the study period. to adjust for differences in age and sex in the suicide rate and population structure, we included the age, sex, and economic activity status of the suicide victims, the year of incidence and the offset term of population size in the regression equation as the confounding variables. mathematically, the regression equation is written as follows: the temporal variation was modeled by comparing the actual frequencies of suicides with the expected values based on the assumption that the suicides are equally distributed. the exponential of the regression coefficient (β) represents the incidence risk ratio (irr), which describes the multiplicative effect of the corresponding independent variable on the risk [ ] [ ] [ ] . a significant irr indicates that there is a significant difference in the adjusted suicide risk between the corresponding month (or day of the week) and the reference period of time. in the present study, the suicide risks for december and saturday (which previous studies reported as being the periods of lowest risk [ ] [ ] [ ] ) were used as references to examine the respective monthly and daily patterns of suicide. in the present study, the seasons were defined as follows: spring (from march to may), summer (from june to august), autumn (from september to november) and winter (from december to february) [ ] . in all statistical analyses, a p-value smaller than % was considered to be statistically significant. all of the statistical work was performed using the sas statistical software package for windows, version . . of the charcoal burning suicide victims, . % (n = ) were men and . % (n = ) were women. the proportions of those who were working and non-working were . % (n = ) and . % (n = ), respectively. the economic activity status of the remaining . % (n = ) of victims was unknown. only those who were recorded as either working or non-working were included in the analyses. thus, a total of working men, working women, non-working men, and non-working women were included in the analysis of the influence of economic activity status and sex on the temporal variation in charcoal burning suicides. overall, moderate temporal variations were observed in the monthly patterns of charcoal burning suicides ( table ) . a peak was observed in april (spring) (irr = . , p = . ), but only among those who were working (irr = . , p = . ). significant sex differences were also observed. whereas men were less likely to commit suicide in summer (june: irr = . , p = . ; july: irr = . , p = . ), women were more likely to commit suicide in spring (april: irr = . , p = . and may: irr = . , p = . ), late autumn (november: irr = . , p = . ), and winter (january: irr = . , p = . ; february: irr = . , p = . ). the interaction of sex and economic activity status was also observed in the monthly pattern of charcoal burning suicides. although no monthly variation was observed in the suicide rate of working men, working women were more inclined to commit suicide in spring (april: irr = . , p = . and may: irr = . , p = . ) and winter (january: irr = . , p = . ). as for the non-working victims, men were less likely to commit suicide in summer (june: irr = . , p = . ), whereas women were more likely to commit suicide in late autumn (november: irr = . , p = . ). significant temporal variations were observed in the daily patterns of charcoal burning suicides ( table to our knowledge, the present study is the first to investigate the temporal patterns of charcoal burning suicide. as charcoal burning is a non-violent suicide method that requires planning to avoid rescue intervention [ ] [ ] [ ] , the temporal variations in suicide observed in this study contradict the findings of many published studies that suicide seasonality only exists in relation to violent methods [ , , ] . this suggests that the specific suicide method is an important factor of suicide seasonality, and that the simple differentiation between violent and nonviolent methods is not applicable to the interpretation of suicide seasonality in hong kong [ ] . in fact, a range of published studies have demonstrated that temporal variations in suicides are method-specific [ , , ] . future research on temporal patterns of suicide should be more method-specific. previous studies have attributed the monthly patterns observed in suicide rates to the influence of seasonalitylinked biological, psychosocial and meteorological correlates [ , , , ] . as the april peak in the seasonality of suicide has also been observed in other suicide methods, charcoal burning suicides may share some of the common causes of suicides by other methods. in addition to the presence of spring peak in april, it is observed that attempters were more likely to commit suicide by burning charcoal in the colder winter months. from a practical point of view, the sub-tropical climate of hong kong would implicitly discourage suicide attempters from burning charcoal in summer to take their own lives. by contrast, the cooler temperatures in winter would make charcoal burning a more acceptable option for suicide. however, the extent to which these explanations are able to account for the monthly pattern of charcoal burning suicides remains unclear. some studies suggest that the correlation between biological factors and seasonal variation is only observed in violent suicides [ , ] . furthermore, the findings on the effects of meteorological variables on suicide seasonality are rather inconsistent and have not been replicated in subsequent studies [ , ] . it is worth noting that only employed women tended to commit suicide by burning charcoal in spring (i.e., april). hence, the seasonal occurrence of particular mental disorders involving suicide ideation fails to explain the temporal variations in charcoal burning suicides. in fact, this is in line with the observation that charcoal burning suicide victims were less likely to be associated with psychiatric illness or substance abuse, compared with those who killed themselves using other methods [ ] [ ] [ ] [ ] [ ] . we expect that more detailed data on the events prior to the death of charcoal burning suicide completers, and on what the suicide attempters were thinking, will help us to explore this knowledge gap in future studies. the results confirm our hypothesis concerning the daily pattern of charcoal burning suicides. the risk of charcoal burning suicide was found to be higher on weekdays (i.e., monday, tuesday, and thursday) than on weekends. this is consistent with most of the other published findings, which report a peak at the beginning of the week [ , , , ] . as suggested by erazo et al. [ ] , a significantly higher rate of suicide on monday seems to be best explained in terms of socio-psychological variables. relatively speaking, a sense of personal failure and isolation is more likely to be triggered in a depressive person at the beginning of the working week, when their surroundings reflect their duties [ ] . a recent study on the relationship between the weekend, work, and well-being also indicated that both men and women tended to experience an enhanced sense of well-being during the weekend compared with working days [ ] . yet, the second peak on thursday observed in the present study is rather novel in the literature. further investigation of the relationship between weekdays and psychological stress is warranted. in line with our expectations, there were pronounced differences in the temporal patterns of charcoal burning suicides in relation to sex. the results identified marked peaks in the rates of charcoal burning suicide in spring and winter (january, february, april, may and november) for working-age women, a less obvious spring peak with a summer nadir was observed for working-age men. this seasonal difference in the magnitude of variation] may be further explained by gender differences in relation to thermal comfort. in an earlier physiological study, lan et al. [ ] found that chinese women were more sensitive to temperature differences than men and that women preferred a relatively warmer environment because they had a higher comfortable operative temperature. it can thus be expected that women are more inclined to burn charcoal in "cold months" and men are less likely to do so in "hot months". as our knowledge of the determinants of charcoal burning suicide remains scant, further research is needed to investigate the differential effects of charcoal burning on vulnerable men and women in terms of monthly patterns. it is worth noting that the influence of employment status on monthly and daily patterns of charcoal burning suicides differed considerably between men and women. according to our data, the monthly variations in suicide risk were more pronounced for non-working men and working women, whereas the daily variations were more apparent for working men and non-working women. it appears that economic activity status either strengthens or weakens the magnitude of the temporal variations in charcoal burning suicide, rather than serving as a determinant that alters the temporal distribution. this may indicate that active employment only serves as a stabilizing factor that protects individuals from various lifethreatening forms of behavior (e.g. alcohol consumption or misuse of illicit drugs) [ ] and thereby implicitly influences the timing of suicide among specific groups of individuals, but not the whole population. accordingly, the nature and magnitude of these effects should be recognized in future studies to develop a more effective approach to suicide prevention in hong kong. our findings contribute to the existing suicide research by extending our scientific knowledge of the temporal patterns of suicidal behavior. in practice, the results of this study may increase the awareness of clinicians, volunteers, and other stakeholders of the most probable timings of suicide, when at-risk individuals may be more vulnerable to suicidality [ , , ] . a greater understanding of the temporal patterns of suicidal behavior may contribute to establishing more effective suicide prevention strategies [ ] . in particular, the different patterns of suicide risk observed in each subgroup suggest that intervention practices for charcoal burning suicides should be more group-specific. several caveats on our findings need to be mentioned. first, the present study failed to separate the unemployed victims from the economically inactive victims due to the limited information available from the dataset. the employed and unemployed victims were expected to have similar variations in suicide risk, whereas the unemployed and economically inactive victims were likely to commit suicide at different times [ ] . future research should independently examine the temporal patterns of all three groups to gain a more comprehensive picture of the influence of economic activity status on suicide risk among charcoal burning victims. second, we only investigated the temporal variation in charcoal burning suicides among the usual working-age population ( - ). our study did not consider the situation of older adults. nonetheless, older adults comprised a relatively insignificant proportion of the total number of charcoal burning suicides (n = ) over the study period. third, the present study did not include individual information on alcohol consumption, history of substance abuse or mental disorders, which are all known to heighten the risk of suicide [ , , [ ] [ ] [ ] . from an epidemiological perspective, seasonal changes in the course of depressive disorder, its treatment indices, and suicide, all appear to coincide and indicate that depressive episodes are an important determinant of the temporal variation in suicide [ ] [ ] [ ] ] . to provide a more complete picture of temporal variation in suicide, researchers should also examine the mental health background of suicide victims. future analyses should include these variables to develop a more comprehensive surveillance and monitoring system for detecting suicidal behavior. charcoal burning suicide in posttransition hong kong burning charcoal: a novel and contagious method of suicide in asia the contribution of charcoal burning to the rise and decline of suicides in hong kong from charcoal-burning suicides and strategies for prevention restricting the means of suicide by charcoal burning charcoal burning suicides in hong kong and urban taiwan: an illustration of the impact of a novel suicide method on overall regional rates seasonal variation in suicide in a predominantly caucasian tropical/subtropical region of australia seasonality in violent suicide but not in nonviolent suicide or homicide seasonal patterns of suicide, depression and electroconvulsive therapy analysis of the seasonal pattern in suicide the influence of seasonal change on suicidal behavior in italy decreasing tendency of seasonality in suicide may indicate lowering rate of depressive suicides in the population are seasonalities in suicide dependent on suicide methods? a reappraisal inequalities in daily variations of deaths from suicide in lithuania: identification of possible risk factors the monthly and weekly distribution of suicide seasonality and climatic associations with violent and nonviolent suicide: a population-based study seasonality in suicides: the influence of suicide method, gender and age on suicide distribution in italy perceived job insecurity and worker health in the united states employment status influences suicide mortality in europe the lot of the unemployed: a time use perspective.: working paper , iza institute for labor seasonal variation in suicide: is there a sex difference seasonal variation in suicide occurrence in finland a comparison of seasonal variation between suicide deaths and attempts in hong kong sar world health organization: the tenth revision of the international classification of diseases and related health problems the design and analysis of cohort studies elderly suicide and the sars epidemic in hong kong a revisit on older adult suicides and severe acute respiratory syndrome (sars) epidemic in hong kong an introduction to generalized linear models: poisson regression seasonal patterns of suicides over the period of socio-economic transition in lithuania seasonal variation in specific methods of suicide: a national register study of finnish people seasonality of suicides: environmental, sociological and biological covariations seasonal variation in plasma ltryptophan availability in healthy volunteers: relationships to violent suicide occurrence in humans, the seasonal variation in poly-unsaturated fatty acids is related to the seasonal variation in violent suicide and serotonergic markers of violent suicide seasonal associations between weather conditions and suicide: evidence against a classic hypothesis seasonal changes in -h patterns of suicide rates: a study on train suicides in the netherlands sex-specific time patterns of suicidal acts on the german railway system: an analysis of cases weekends, work, and well-being: psychological need satisfactions and day of the week effects on mood, vitality, and physical symptoms investigation of gender difference in thermal comfort for chinese people employment status influences the weekly patterns of suicide among alcohol misusers temporal fluctuations and seasonality in attempted suicide in europe: findings from the who/ euro multicentre study on parasuicide seasons and meteorological factors in suicidal behaviour do weather, day of the week, and address affect the rate of attempted suicide in hong kong? mental disorders and comorbidity in suicide suicide as an outcome for mental disorders: a meta-analysis psychiatric illness and risk factors for suicide in denmark cite this article as: law and leung: temporal patterns of charcoal burning suicides among the working age population in hong kong sar: the influence of economic activity status and sex the authors are indebted to professor paul yip of the university of hong kong hkjc centre for suicide research and prevention, and the census and statistics department of hong kong who kindly shared the data necessary for our analysis. role of funding source. all authors declare that they have no competing interests. key: cord- -oo wler authors: chung, pak-kwong; zhang, chun-qing; liu, jing-dong; chan, derwin king-chung; si, gangyan; hagger, martin s. title: the process by which perceived autonomy support predicts motivation, intention, and behavior for seasonal influenza prevention in hong kong older adults date: - - journal: bmc public health doi: . /s - - -x sha: doc_id: cord_uid: oo wler background: this study examined the effectiveness of a theoretical framework that integrates self-determination theory (sdt) and the theory of planned behavior (tpb) in explaining the use of facemasks to prevent seasonal influenza among hong kong older adults. methods: data were collected at two time points in the winter in hong kong, during which influenza is most prevalent. at time , older adults (n = ) completed self-report measures of sdt (perceived autonomy support from senior center staff, autonomous motivation for influenza prevention) and tpb (attitude, subjective norm, perceived behavioral control, and intention for influenza prevention) constructs with respect to facemask used to prevent infection. two weeks later, at time , participants’ acceptance of a facemask to prevent influenza in the presence of an experimenter with flu-like symptoms was recorded. results: path analysis found that perceived autonomy support of senior center staff was positively and significantly linked to autonomous motivation for facemask use, which, in turn, was positively related to intentions to wear facemasks through the mediation of attitude, subjective norm, and perceived behavioral control. however, the effect of intention on facemask use was not significant. conclusions: results generally support the proposed framework and the findings of previous studies with respect to intention, but the non-significant intention-behavior relationship may warrant future research to examine the reasons for older adults not to wear facemasks to prevent seasonal influenza despite having positive intentions to do so. seasonal influenza is an acute epidemic of the influenza virus that quickly and easily spreads from person to person [ ] . annual seasonal epidemics peak during the winter months in temperate regions such as hong kong. epidemics cause mild-to-severe illness and can be fatal in vulnerable groups such as the elderly [ ] . everyday preventive actions, such as facemask wearing, play an important role in the prevention seasonal influenza epidemics [ , ] . this is because the main route of human-to-human transmission of the influenza virus is via respiratory droplets when an individual is close contact with someone who has the influenza virus and displays influenza symptoms [ ] . in community settings, wearing a facemask is an effective means to minimize transmission of influenza, particularly in areas of high population density. in order to promote the adoption of behaviors like facemask use to prevent seasonal influenza infection, previous research has demonstrated that psychological factors such as motives and intentions are likely play a key role [ , ] . researchers have attempted to predict and understand health behavior using behavioral theories and models adopted from social psychology [ ] . among the models that have been applied to understand influenza prevention behaviors, most have adopted a social-cognitive approach, in which preventive behaviors such as vaccination and facemask wearing are viewed as intentional behaviors based on beliefs and expectancies [ , , ] . prominent among these social cognitive approaches is the theory of planned behavior (tpb) [ ] . according to the theory, intention, defined as the extent to which individuals will invest effort in pursuit of an action, is the most proximal predictor of behavior. intention is the function of attitude (i.e., personal evaluation of how good, useful, valuable, and pleasant the behavior is), subjective norm (i.e., beliefs that the behavior is consistent with the expectations of significant others), and perceived behavioral control (i.e., beliefs in the availability of sufficient personal resources, in relation to barriers or risk factors, to execute the behavior). the tpb has been widely applied and tested in health-related behavioral contexts with meta-analytic studies supporting its effectiveness in predicting various health behaviors [ , ] . the predictive efficacy of the tpb with respect to influenza prevention has also been supported in research on influenza vaccination behaviors [ , ] . apart from the tpb, another important theory in social psychology that has been frequently applied in health contexts is self-determination theory (sdt) [ , ] . sdt makes the distinction between different forms of motivation based on its quality rather than quantity: autonomous motivation, controlled motivation, and amotivation. autonomous motivation is the most self-determined form of motivation. autonomously motivated individuals perform behaviors for the intrinsic value of the behavior, or to attain personally-important values or goals that represent their true sense of self. in contrast, individuals experiencing actions as controlled motivated engage in behaviors due to external pressures or externally-referenced obligations. amotivation represents a lack of motivation such that individuals do not know why they engage in their actions at all. individuals experiencing actions as controlled motivated will only perform an action when the external demands or controlling contingencies are present and the actions will cease once the contingencies are no longer present. of the three types of motivation identified in sdt, autonomous motivation is proposed to be more favorable to behavioral persistence and well-being because the individual is motivated for self-referenced reasons and in the absence of external reinforcement or contingency [ ] . consistent with the need to promote autonomous motivation toward health behaviors, according to the sdt, creating a context or 'environment' that cultivates autonomous motivation is an effective means to promote autonomous motivation and change behavior [ , ] . in an influenza prevention context, interventionists may capitalize on autonomy support techniques as a means to promote autonomous motivation [ ] . for communitydwelling older adults, their senior center serves as an important vehicle to present autonomy-supportive messages to promote behaviors that could enhance health and wellbeing, including preventive behaviors to reduce the transmission of potentially life-threatening infections [ ] . recent approaches have attempted to integrate concepts from the tpb and sdt in a unified model to explain health behavior. the integrated model proposes that the motivational variables from sdt are distal predictors of the social cognitive variables from tpb, which are, in turn, considered the proximal antecedents of action [ , ] . the rationale for the integration arises from a key tenet of sdt that individuals who perceive their reasons for acting autonomously should view their behavior as one they should approach. in order to enact the behavior, the individual should align his or her beliefs regarding future engagement in the behavior to be consistent with their motives (i.e., to form positive beliefs about the behavior and form intentions to engage in it). promoting autonomous motivation, therefore, may be a means to promote behavioral engagement through the enhancement of positive beliefs regarding the behavior and the formation of intentions to engage in the behavior in the future. the model has been tested in many health contexts including physical activity, binge drinking, injury management, sugar consumption, and myopia prevention [ ] [ ] [ ] [ ] [ ] [ ] . although a recent study also applied the integrated model to predict behavior in the context of h n pandemic, participants were presented with a hypothetical situation and were not actually facing an actual pandemic and no actual facemask wearing behavior was assessed. [ ] . even though intention is theoretically the most proximal predictor of behavior, there has been growing number of concerns about the differential predictive power of intention on health behavior, and the so-called intention-behavior gap has raised concerns over the adequacy of intentions in explaining future behavior [ ] [ ] [ ] . it is, therefore, important that test of the integrated model include prospective measures of actual behavior, particularly in influenza prevention contexts. the purpose of the current study was to examine the efficacy of an integrated model based on sdt and tpb to predict facemask wearing to prevent seasonal influenza in a sample of hong kong older adults. we adopted a two-week prospective correlational design during hong kong's winter, the peak season for seasonal influenza, and we included an actual measure of the target behavior. specifically, we measured the motivational and social cognitive variables from the integrated model at time (baseline) and followed that up two-weeks later at time with an assessment of actual facemaskwearing behavior. building on the integrated model, it was hypothesized that: ( ) perceived autonomy support from senior center staff for facemask wearing would be positively and directly related to autonomous motivation (hypothesis a) and positively and indirectly related to attitude, subjective norm, and perceived behavioral control via the mediation of autonomous motivation (hypothesis b); ( ) autonomous motivation would be positively and directly related to attitude, subjective norm, and perceived behavioral control (hypothesis a) and positively and indirectly related to intention via the mediation of attitude, subjective norm, and perceived behavioral control (hypothesis b); ( ) attitude, subjective norm, and perceived behavioral control would be positively and directly associated with intention (hypothesis a) and positively and indirectly related to actual facemask wearing behavior via the mediation of intention (hypothesis b). participants ethical clearance was granted by the committee of research ethics and safety (hasc) at hong kong baptist university. we obtained approval and on-site assistance to recruit participants from one senior center in hong kong using convenience sampling. this center has over registered chinese-speaking community-dwelling hong kong older adults aged years and older. a total of older adults expressed an interest in participating to senior center staff and members of the research team. of these eligible participants, agreed to participate and signed consent forms (response rate = . %). the sample comprised of males and females (m age = . , sd = . , range to ) participated the study at time . at time , participants ( males, females; m age = . , sd = . ) remained in the study (retention rate = . %). data were collected at two time points with a two-week interval in the november of . at time , during the peak season of winter influenza in hong kong, participants completed survey measures of study variables under the supervision of researchers following an introductory session in which the purpose and procedure of the study was explained and written informed consent obtained. the surveys took to min to complete. senior center staff were not present during the completion and were not able to see participants' responses. at time , participants were invited to a face-to-face interview in a private room to ostensibly assess their knowledge of h n . the true purpose of the interview was to assess participants' facemask wearing behavior for influenza prevention. during the course of the interview, the interviewer wore a facemask and feigned influenzalike symptoms (e.g., coughing, sneezing). before the start of the interview, the interviewer told the participants in an offhand manner that he/she had caught "the 'flu", and that surgical facemasks were available at the desk that they could take and use for free. this allowed the interviewers to record participants' facemask-wearing behavior. on completion of the interview, participants were debriefed regarding the cover story and informed that the interviewer had feigned influenza symptoms and worn the facemask as a prop to model the behavior. perceived autonomy support perceived autonomy support from staff of senior center was measured using the six-item health care climate questionnaire (hccq) [ ] . participants were provided with a common stem: "when the staff at the senior center asks me to wear a facemask in an enclosed public place…" followed by the six items (e.g., "i feel that he/ she has provided me choices and options"). responses were made on a -point scale anchored by ("not at all true") and ("very true"). the chinese version of the hccq has demonstrated sufficient validity and reliability [ ] . the six-item autonomous motivation subscale from the treatment self-regulation questionnaire (tsrq) [ ] was used to measure autonomous motivation. the stem of tsrq items was modified to refer the specific behavior of interest (i.e., "i want to wear a facemask in an enclosed public place because …"). participants responded to items on -point likert scales with ("not at all true") and ("very true") as scale anchors. the chinese version of tsrq has demonstrated sufficient validity and reliability [ ] . measure of the tpb variables were based on ajzen's guidelines [ ] . measures of subjective norm ( items; e.g., "it is expected of me to wear facemask in an enclosed public place in the forthcoming month."), perceived behavioral control ( items; e.g., "it is possible for me to wear facemask in an enclosed public place in the forthcoming month."), and intention ( items; e.g., "i intend to wear facemask in an enclosed public place in the forthcoming month.") were rated on -point likert scales with ("strongly disagree") and ("strongly agree") as anchors. attitudes were measured using items preceded by a common stem, "for me to wear facemask in an enclosed public place in the forthcoming month would be …" followed by a series of -point semantic differential scales: extremely harmful-extremely beneficial, extremely unpleasant-extremely pleasant, extremely worthless-extremely valuable, extremely badextremely good, and extremely unenjoyable-extremely enjoyable. facemask-wearing behavior was assessed at time during the face-to-face interview. the interviewer disclosed in an offhand manner that they had caught influenza and feigned influenza symptoms. participants were made fully aware of the availability of facemasks and that they were free to use. the interviewer was trained to observe and record the correct use of the facemasks according to world health organization guidelines (i.e., complete coverage of mouth and nose) [ ] . the interviewers recorded a ("yes") when participants took and used the facemasks correctly and otherwise recorded a ("no"). control variables included past facemask-wearing habit (i.e., whether or not they had worn facemasks previously; item), knowledge of the benefits of facemask wearing (i.e., knowing that facemask wearing can prevent influenza; item), frequency of influenza infection during the past months ( item), and perceived susceptibility. perceived susceptibility (e.g., "i have an increased risk of falling ill with influenza"; items) was rated on a point likert scale with ("strongly disagree") and ("strongly agree") as scale anchors [ ] . given that the time facemask wearing behavior was a categorical variable (yes/no), the proposed integrative model (see fig. ) was tested using path analysis (i.e., observed variables) with a variance-adjusted weighted-least squares (wlsmv) estimation method using the mplus . [ ] . variables including facemask wearing habit, knowledge of facemask wearing benefits, frequency of influenza during the past months, and perceived susceptibility were included as control variables. adequacy of the fit of the proposed model with the data was based on multiple criteria for assessing goodness of fit including the comparative fit index (cfi), the root-mean-square error of approximation (rmsea) and the weighted root mean square residual (wrmsr). values exceeding . for the cfi and less than . and . for the rmsea and wrmsr [ , ] , respectively, indicate good fit. for our tests of mediated effects, mediation was confirmed when the indirect effect of a predictor variable (e.g., autonomous motivation) on an outcome variable (e.g., intention) via a mediator (e.g., attitude) was statistically significant and the confidence interval of the effect size did not include zero. in terms of the facemask wearing habit, most of the participants reported wearing facemasks previously (n = ), while a small number of them reported that they did not been used to wearing facemasks previously (n = ). with respect to knowledge of the benefits of facemask wearing, most of the participants reported knowing facemask wearing can prevent flu (n = ), while a small number reported they did not know facemask wearing can prevent flu (n = ). with regards to the frequency of influenza during the past months, most of the participants reported that they had not caught influenza (n = ). in comparison, only participants reported that they caught influenza once, seven participants reported they had had the flu twice, and only three participants reported catching influenza three times. missing data analysis revealed no significant pattern (missing data = . %) and the small number if missing cases was replaced using mean substitution. descriptive statistics and intercorrelations of the study variables are presented in table . the model exhibited adequate fit with the data, χ ( ) = . , p = . , cfi = . , wrmr = . , rmsea ( % ci) = . (. , . ). direct, indirect, and total effects of the path estimates of the integrated model are presented in table and fig. . effects of the control variables were not significant except the effect of frequency of influenza over the previous six months on autonomous motivation (β = −. , %ci [−. to −. ], p = . ), and they are not, therefore, displayed in fig. . focusing on the effects encompassed by hypothesis , we observed a statistically significant and positive effect of perceived autonomy support on autonomous motivation consistent with our hypothesis (hypothesis a). the indirect effects of perceived autonomy support on attitude and subjective norm were statistically significant as hypothesized (hypothesis b), although the direct effects were not. as predicted, the total, direct, and indirect effects of perceived autonomy support on perceived behavioral control were also statistically significant (hypothesis b). statistically significant and positive associations were observed for autonomous motivation on attitude, subjective norm, and perceived behavioral control, as hypothesized (hypothesis a). the indirect effects of autonomous motivation on intention mediated by attitude, subjective norm, and perceived behavior control were all statistically significant, consistent with predictions (hypothesis b). we found statistically significant and positive effects of attitude, subjective norm, and perceived behavioral control on intention, as predicted (hypothesis a). however, contrary to predictions, the effect of intention on our measure of facemask wearing was small and not statistically significant (hypothesis b). building on an integrated model of sdt and tpb [ , , ] , we tested effects among perceived autonomy support, autonomous motivation, attitudes, subjective norms, perceived behavioral control, intention, and behavior for facemask wearing during peak influenza season among elderly people in hong kong. consistent with our hypotheses, we found statistically significant and positive effects of ( ) perceived autonomy support on autonomous motivation, attitude, subjective norm, and perceived behavior control; ( ) autonomous motivation on attitude, subjective norm, and perceived behavioral control, and intention; and ( ) attitude, subjective norm, and perceived behavioral control, on intention. there were also significant and positive indirect effects of perceived autonomy support on attitude, subjective norm, and perceived behavior control via autonomous motivation, and of autonomous motivation on intentions via attitude, subjective norm, and perceived behavior control. however, we found no effect of intention on our measure of actual facemask wearing, and, consequently, no indirect effects of the motivational and social-cognitive variables on behavior mediated by intention. our findings, therefore, suggest that the motivational and social-cognitive constructs outlined in the integrated model are effective in predicting intentions to wear a facemask during the peak winter season, but, critically, intentions were not predictive of individuals' actual engagement in facemask wearing behavior. [ , ] . the finding is also consistent with the findings of a previous study on facemask wearing [ ] . the results suggest that establishing an autonomy supportive environment or 'motivational climate' toward influenza prevention behaviors such as facemask wearing will be effective in fostering autonomous motivation toward the behavior. consistent with previous studies of influenza prevention behaviors such as facemask wearing and vaccination using the tpb [ , , ] , attitudes, subjective norms, and perceived behavior control had positive, significant, and medium-to-large associations with the intentions of wearing facemasks in hong kong older adults. among these three variables, perceived behavioral control had the strongest effects relative to attitudes and subjective norms. it was also the most prominent variable in the transmission of indirect effects of autonomous motivation on intention. given that the tpb is, by and large, an integration of the personal (i.e., attitude) and social (i.e., subjective norm) antecedents of intention from the reasoned action approach [ , ] , and the self-efficacy related component from social cognitive theory [ ] , the increase of older adults' personal resources (e.g., selfefficacy) and the decrease of the hindrance from barriers (e.g., easy access to facemasks when needed) seem to be most efficacious in accounting for variance in intentions to engage in the focal health behavior. current findings provide formative evidence to support interventions to facilitate greater confidence in wearing facemasks and to overcome barriers to doing so. the significant and positive direct effects of perceived autonomy support on attitude and perceived behavioral control indicated that a supportive motivational climate may affect the belief-based tpb variables. this is in line with previous studies [ , , , ] and it further corroborates the integrated model [ , ] . that is, autonomous motivation from sdt underpins the belief-based social cognitive variables of tpb, and the current study extends this to facemask wearing to prevent influenza transmission. the prominent role of control-related beliefs for this health behavior, and its mediating role in translating autonomous motives into intentions, is consistent with other theories which feature self-efficacy as a prominent component [ ] . it is also consistent with previous research that has adopted the integrated model and demonstrated that perceived behavioral control is a key predictor and mediating factor of the influence of autonomous motivation on intentions [ ] . the intentions of facemask wearing alone may be insufficient or unimportant when it comes to engaging in this particular behavior. in a post hoc analysis, we found that the majority of participants ( . %) scored above the mid-point on the intention scale but only two fifths of them chose to wear the face masks ( . %) in our scenario. considering these data, it would be reasonable to assume that the majority of participants should be considered inclined abstainers or unsuccessful intenders [ , ] , or have weak or unstable [ ] [ ] [ ] intentions. given that older adults' facemask wearing habits, knowledge of whether wearing facemasks can prevent influenza, frequency of influenza over the previous months, and perceived susceptibility to influenza were controlled for, it is reasonable to conclude that the current findings are consistent with the well-documented intention-behavior gap. a number of factors may account for this 'gap'. first, it emerged from the qualitative debriefing session conducted after the study had been completed that many of the participants chose not to wear a facemask because the interviewer was wearing a facemask, and they believed that they were, therefore, safe. others reported that they were put off wearing facemasks themselves because it would make it difficult or uncomfortable to breathe, a notable barrier. as this is anecdotal evidence rather than a formal assessment, it may be important in future research to examine participants' specific beliefs regarding the behavior, rather than global or direct measures of attitudes and perceived behavioral control. such an approach may identify the influential behavioral (e.g., beliefs that people with illnesses will wear facemasks to reduce risk to others) and control (e.g., wearing masks makes it difficult or uncomfortable to breathe) beliefs that may influence the formation of intentions. omission the beliefs that precede intentions aside, it may also be important to study the underlying volitional mechanisms from dual-phase models of action like the model of action phases [ ] and the health action process approach [ ] that determine the enactment of intentions. incorporation of volitional components like implementation intentions, action planning, and coping planning into the study of facemask wearing may assist in identifying the possible moderators of the intention behavior relation. similarly, it may also be important to look at the implicit, non-conscious or 'automatic' influences on action. research has indicated that self-reported habit predicts behavior as do implicitly measured attitudes and motives [ ] [ ] [ ] . such influences likely account for action independent of the intentional route to behavior, and therefore determines action beyond an individual's awareness. the likely process involved is that the implicit beliefs are associated with schema, or memory structures, which outline patterns of action which have been well learned and reinforced over time. such patterns are activated when the implicit belief or attitude is cued, and, as a consequence, an individual's behavior is initiated automatically [ , ] . this does not mean that individuals act like 'automatons' , blindly carrying out actions. the actual behavior may involve considerable planning and effort, it is just that the behavioral pattern is set in motion in a quick, efficient manner making the behavior subjectively very easy to enact. implicit beliefs are also more likely to facilitate the enactment of the intended action, or failing to do the action, if it is either rewarding or relatively easy to do. future research should examine individuals' implicit beliefs toward illness and implicit beliefs toward the behavior, with respect to facemask wearing and assess their contribution to action. this would be consistent with further integrated models that have attempted to incorporate implicit components alongside motivational and volitional components of action in a unified framework [ ] . the current study has numerous strengths including a focus on an important health-related behavior aimed at preventing influenza infection in a vulnerable population and has the potential to save lives, recruitment of a hard-to-reach population of older adults, adoption of an integrated theoretical model that has shown efficacy in predicting health behavior, and the use of valid and reliably instruments and a prospective design, and the use of an externally-verified observational measure of behavior instead of self-reports which have inherent biases. although our findings offer insight into the motivational processes that relate to facemask use in hong kong older adults to prevent influenza transmission during peak season, a number of limitations of the study should be identified and discussed. first, participants in the current study were ethnically and geographically homogeneous since they were recruited from the same senior center. all participants were hong kong chinese, and most of them were female. in future, it would be important to replicate the findings in more diverse sample of older adults to provide further evidence on the validity and generalizability of study findings. secondly, inference of causal relations among variables in the integrated model cannot be made even with the adoption of a prospective design. the causal direction of effects in the model can only be inferred from the theory rather than the data [ ] , it is, therefore, imperative that researchers also adopt experimental paradigms to manipulate key variables in the nomological network proposed by the theory and observe their effects on outcomes. finally, the current study did not conduct an a priori statistical power analysis and adopted a manifest rather than latent variable approach given the relatively small sample. future research should seek to conduct a power analysis beforehand, collect data from a larger sample and use a latent variable modeling approach which would control for measurement error [ ] . in conclusion, findings of the current study provided support for the motivational aspects of the integrated model to the wearing of facemasks to prevent seasonal influenza in a sample hong kong older adults. however, our research did not support the link between intentions to wear facemasks and a situated decisional measure of facemask wearing in a real-life context. further examination of the potential alternative processes and moderators of the link between intentions and behavior in this context may provide insight on contexts in which intentions to wear facemasks lead to actual facemask wearing behavior, and the processes involved. abbreviations cfi: comparative fit index; hccq: health care climate questionnaire; rmsea: root-mean-square error of approximation; sdt: self-determination theory; tpb: theory of planned behavior; tsrq: treatment self-regulation questionnaire; wlsmv: variance-adjusted weighted-least squares; wrmr: weighted root mean square residual world health organization. influenza (seasonal) seasonal influenza in adults and children-diagnosis, treatment, chemoprophylaxis, and institutional outbreak management: clinical practice guidelines of the infectious diseases society of america facemasks and intensified hand hygiene in a german household trial during the / influenza a (h n ) pandemic: adherence and tolerability in children and adults mathematical modeling of the effectiveness of facemasks in reducing the spread of novel influenza a (h n ) advice on the use of masks in the community setting in influenza a(h n ) outbreaks psychosocial factors influencing the practice of preventive behaviors against the severe acute respiratory syndrome among older chinese in hong kong decision on influenza vaccination among the elderly: a questionnaire study based on the health belief model and the multidimensional locus of control theory. scand j prim health care theoretical frameworks in exercise psychology meta-analysis of the relationship between risk perception and health behavior: the example of vaccination determinants of influenza vaccination among healthcare workers from intentions to actions: a theory of planned behavior prospective prediction of health-related behaviours with the theory of planned behaviour: a metaanalysis theory of planned behavior and adherence in chronic illness: a meta-analysis determinants of older adults' intentions to vaccinate against influenza: a theoretical application factors affecting intention to receive and self-reported receipt of pandemic (h n ) vaccine in hong kong: a longitudinal study intrinsic motivation and self-determination in human behavior the "what" and "why" of goal pursuits: human needs and the self-determination of behavior motivational predictors of weight loss and weight-loss maintenance a meta-analysis of the effectiveness of intervention programs designed to support autonomy preventing the spread of h n influenza infection during a pandemic: autonomy-supportive advice versus controlling instruction senior citizens centers: what they offer, who participates, and what they gain integrating the theory of planned behaviour and self-determination theory in health behaviour: a meta-analysis an integrated behavior-change model for physical activity myopia prevention, near work, and visual acuity of college students: integrating the theory of planned behavior and self-determination theory autonomous forms of motivation underpinning injury prevention and rehabilitation among police officers: an application of the trans-contextual model theoretical integration and the psychology of sport injury prevention predicting sugar consumption: application of an integrated dual-process, dual-phase model perceived autonomy support in physical education and leisure-time physical activity: a cross-cultural evaluation of the trans-contextual model predicting alcohol consumption and binge drinking in company employees: an application of planned behaviour and self-determination theories how big is the physical activity intention-behaviour gap? a meta-analysis using the action control framework time to retire the theory of planned behaviour bridging the intention-behaviour gap: planning, self-efficacy, and action control in the adoption and maintenance of physical exercise validating the theoretical structure of the treatment self-regulation questionnaire (tsrq) across three different health behaviors constructing a tpb questionnaire: conceptual and methodological considerations mplus user's guide goodness of fit evaluation in structural equation modeling evaluating cutoff criteria of model fit indices for latent variable models with binary and continuous outcomes self-determination theory applied to health contexts a metaanalysis predicting and changing behavior: the reasoned action approach mind the gap: bringing our theories in line with the empirical data -a response to commentaries social foundations of thought and action: a social-cognitive theory modeling health behavior change: how to predict and modify the adoption and maintenance of health behaviors the trans-contextual model of autonomous motivation in education: conceptual and empirical issues and meta-analysis inclined abstainers': a problem for predicting health related behaviour temporal stability as a moderator of relationships in the theory of planned behaviour goal conflict and the moderating effects of intention stability in intention-behavior relations: physical activity among hong kong chinese mediator of moderators: temporal stability of intention and the intention-behavior relation thought contents and cognitive functioning in motivational and volitional states of mind a review and analysis of the use of 'habit' in understanding, predicting and influencing health-related behaviour investigating the predictive validity of implicit and explicit measures of motivation on condom use, physical activity, and healthy eating cognitive control and the non-conscious regulation of health behavior what measures of habit strength to use? using metaanalytic path analysis to test theoretical predictions in health behavior: an illustration based on meta-analyses of the theory of planned behavior manifest variable path analysis: potentially serious and misleading consequences due to uncorrected measurement error not applicable. this study was funded by faculty research grant (frg), hong kong baptist university (grant number frg - - - ). all data supporting our findings will be shared upon request. all authors were involved in the design of the study protocol. pkc, cqz, jdl, and dkc were involved in the data acquisition. pkc and cqz conducted all analyses and wrote the first draft. pkc, cqz, dkc, and msh contributed to the interpretation of the results. all authors critically reviewed the manuscript and approved the final version.ethics approval and consent to participate the current study involves human participants and the research protocol had been approved by the committee of research ethics and safety (hasc) at hong kong baptist university. all participants provided written informed consent to participate. not applicable. the authors declare that they have no competing interests. key: cord- -tph d fl authors: de deyn, michelle lee zhi qing; ng, qin xiang; loke, wayren; yeo, wee song title: a tale of two cities: a comparison of hong kong and singapore's early strategies for the coronavirus disease (covid- ) date: - - journal: j infect doi: . /j.jinf. . . sha: doc_id: cord_uid: tph d fl nan in hksar, it is known that community-wide masking was practiced by the general population at an early stage of the pandemic . based on news reports and official press releases, it is evident that many asian countries, which have successfully contained the first wave of infections, are now experiencing a second wave of imported cases from abroad and worsening local transmission . as the authors rightly mentioned, singapore and hksar share several similarities in that they are both sprawling city states with developed economies, a high trade-to-gross domestic product (gdp) ratio, advanced infrastructure and healthcare systems, and they both had varying successes thus far in the management of the ongoing pandemic, albeit adopting different approaches , . singapore saw her first imported case of the novel coronavirus infection on january . prior to this, the authorities had a working multi-ministry taskforce, issued travel advisories for china to the public, precautionary advisory to preschools (good hygiene, travel declarations and temperature screening for staff) and implemented temperature screening at land and sea checkpoints. given the evolving situation in china at that time and the high volume of international travel to singapore, the singapore government had accurately pre-empted the possibility of more suspect cases and imported cases . after the severe acute respiratory syndrome-related coronavirus (sars-cov) outbreak, singapore authorities had put in place a multi-ministry taskforce and a disease outbreak response system condition (dorscon) framework that enables the whole-of-government to respond immediately to any disease outbreak and guide interventions . while hong kong saw her first imported case on january and had taken similar pre-emptive measures prior to this . in terms of the alert level, singapore raised its risk assessment (in accordance with the dorscon framework) from dorscon yellow to dorscon orange on february after the country saw an increased number of cases of local transmission. in hong kong, the serious response level was activated in public hospitals on january and the hospital authority activated the emergency response level on january . both countries contained the first wave of imported cases well and boasted robust testing and contact-tracing capabilities. however, a key difference was that the hong kong government implemented social-distancing measures and partial closures earlier, extending the lunar new year holidays and keeping all schools and government offices closed after the holidays, while the singapore government had all schools (including preschools) running up till the implementation of a sweeping 'circuit breaker' measure on april , only allowing residents to leave their homes to exercise alone or purchase essential items. all private or public gatherings, non-essential services and sports and recreation facilities have ceased. although both countries did not advise compulsory mask-wearing hitherto, most members of public in hong kong chose to wear a mask when going outside anyway. the initial advice from the hong kong government was for people who have respiratory symptoms, visiting hospitals and those travelling to wear a mask (and continue to do so until days after returning). the generally high mask usage amongst the public could be partly due to their previous experience with sars-cov or their distrust in the hksar central government . although there are no official statistics, it was evident from media and news reports that most singaporeans still went about their daily activities without the use of a mask, unless they were unwell . the singapore government has now dramatically reversed their recommendations on the use of masks because it is thought that they may confer additional protection against the covid- , due to the variable incubation period for clinical disease and possibility of asymptomatic spreaders . it is now mandatory to wear a mask when going out. tough laws have been put in place to enforce this; first-time offenders would be fined while egregious cases may be prosecuted in court . the covid (temporary measures) act was passed by singapore parliament on april , and under the act, the government has the powers to make regulations to further prevent or control the incidence or transmission of covid- . either way, it appears that hong kong has managed to flatten the coronavirus curve, while singapore is seeing a rapid upward trend (figure ) , mostly due to an outbreak of cases amongst foreign workers living in the dormitories . there are more than , foreign workers on 'construction work permits' in singapore, and the growing outbreak amongst workers living in the dormitories could be due to the limited space, their culture of communal cooking and sharing food, and communal toilets. given the above context and factors, it is difficult to precisely apportion the contribution of masking versus social distancing, rigorous contact tracing and other control measures to covid- containment. properly-worn face masks probably help stem the spread of the coronavirus, albeit other environmental and ambient factors such as temperature, wind velocity and humidity would also affect how the respiratory droplets travel. although the efficacy of wearing masks in public cannot be stated definitively, we believe the takeaway lessons are clear. caution and pre-emptive measures yield significant preventive benefits in this crisis. the public needs to act responsibly and pay heed to these advice and physical distancing measures. given the escalating medical and socioeconomic costs associated with this pandemic, the adage that 'prevention is better than cure' is especially relevant today. the role of community-wide wearing of face mask for control of coronavirus disease (covid- ) epidemic due to sars-cov- asia pacific steps up covid- efforts as second wave of infections strikes multinationals and the growth of the singapore economy. routledge city states in the global economy: industrial restructuring in hong kong and singapore. routledge confirmed imported case of novel coronavirus infection in singapore; multi-ministry taskforce ramps up precautionary measures macau confirms first case as new disease looms over hong kong. south china morning post flattened the curve for now but hong kong braces for a second coronavirus wave singapore u-turns on wearing masks as local virus cases climb asymptomatic transmission, the achilles' heel of current strategies to control covid- continued stringent implementation and enforcement of circuit breaker measures thousands of people in dorms pose new challenge to singapore virus fight. bloomberg the authors report no conflicts of interest. this research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. the authors alone are responsible for the content and writing of the article. key: cord- -lu ngt r authors: chow, c.b. title: post-sars infection control in the hospital and clinic date: - - journal: paediatr respir rev doi: . /j.prrv. . . sha: doc_id: cord_uid: lu ngt r the recent severe acute respiratory syndrome (sars) outbreak has almost mandated a re-evaluation of infection control practices in hospitals, clinics, schools and domestic environments, especially for patients with respiratory tract symptoms. triage, early case detection followed by prompt isolation and quarantine are major preventive measures. respiratory tract infections are the most common childhood illnesses and paediatric sars poses special problems in diagnosis because of its non-specific presentation. the main lessons learnt from the outbreak were: ( ) despite well established guidelines on infection control precautions, poor understanding of underlying principles and deficiencies in compliance are common among healthcare professionals, especially during emergencies; ( ) even a slight lapse can be fatal; and ( ) over-protection can be counterproductive. hence it is important to: ( ) be protected to protect others; ( ) be vigilant and prepared for emerging infections; ( ) be proficient and scrupulous in infection control measures; ( ) be apposite and practical on personal protective equipments to ensure sustainability; and ( ) be dutiful and prompt in informing of potential threats and work closely with others. sars is a new devastating disease, the understanding of which is still evolving and includes its clinical syndromes, infectivity and transmissibility, optimal treatment and prognosis. children are less commonly infected than adults, they have milder disease, are less infectious and present with non-specific clinical features. however, severe illness can develop in adolescents and young infants. , detailed infection control guidances on sars have been prepared by who, us center for disease control, health canada, health protection agency of uk, ministry of health singapore, cdc of china, cdc of taiwan and the hospital authority of hong kong. a comprehensive review and account of infection control measures will not be attempted. this article makes special reference to children, is based on personal experience and on local systems developed in hong kong. it may need modifying to suit local situations and will need to be updated as new knowledge arises. the incubation as reported by most countries is said to be - days, with a mean of . days. analysis of cases in hong kong revealed that the incubation period lies from - days with a mean of . days. the main mode of transmission differed in different countries. using mathematical and statistical models it was estimated that . % and . % of sars infections in hong kong and singapore were attributable to super-spreading events. it is not known whether the route of transmission affects the incubation period. paediatric summary the recent severe acute respiratory syndrome (sars) outbreak has almost mandated a re-evaluation of infection control practices in hospitals, clinics, schools and domestic environments, especially for patients with respiratory tract symptoms. triage, early case detection followed by prompt isolation and quarantine are major preventive measures. respiratory tract infections are the most common childhood illnesses and paediatric sars poses special problems in diagnosis because of its non-specific presentation. the main lessons learnt from the outbreak were: ( ) despite well established guidelines on infection control precautions, poor understanding of underlying principles and deficiencies in compliance are common among healthcare professionals, especially during emergencies; ( ) even a slight lapse can be fatal; and ( ) over-protection can be counterproductive. hence it is important to: ( ) be protected to protect others; ( ) be vigilant and prepared for emerging infections; ( ) be proficient and scrupulous in infection control measures; ( ) be apposite and practical on personal protective equipments to ensure sustainability; and ( ) be dutiful and prompt in informing of potential threats and work closely with others. ß published by elsevier ltd. sars-coronavirus (cov) can be found in respiratory secretions, saliva, tears, blood, urine and faeces of sars patients. sars-cov is stable in the environment for up to days at room temperature and longer at a lower temperature. survival in a variety of stool suspensions varies depending on the ph, consistency of the stool and possibly other factors (up to days in alkaline, diarrhoeal stool, h in normal stool and h in normal, acidic baby stool). the virus loses infectivity after exposure to different commonly used disinfectants (including alcohol and hypochlorite), and heating at c for min. based on rt-pcr data, % of nasopharyngeal aspirate (npa)/nasal throat swabs tested positive for virus on days - , peaking at % positive on days - , declining to % on days - and are % by day . however, - % of stools tested positive for the virus on days - , peaking at % on days - and falling to % by days - . detection of viral rna has a much lower yield from serum, with only % testing positive on days - , peaking at % on days - of illness and being undetectable by day . viral excretion in npa and stool peaked on days - but viral load in npa specimen was at two orders of magnitude lower than viral excretion in stools. hence, respiratory specimens including nasopharyngeal aspirates, throat swabs or sputum samples were the most useful clinical specimens in the first days of illness, after this stools would be the best choice. infectivity is greatest in the second week of the illness, including those with severe illnesses, but patients can be infective within the first - days. there is no reported instance of transmission before the onset of symptoms of the disease and transmission after the second week of illness is rare. the size of coronavirus is about . mm. sneezing could have an ejection velocity of up to metres per sec and cough metres per sec. the number of droplets produced from coughing is about , talking produces and singing . droplet size varies from mm to mm. large droplets do not travel far and usually settle within metres but droplets of mm can stay in the air for h. with forced ejection a good portion of these droplets can be evaporated rapidly, especially under low humidity and they may suspend in air longer. using fluorescentstained water, it was demonstrated that toilet seats had significant contamination by droplets after flushing and the aerosol effect can be up to the standing height of a child. huge amounts of submicron ( . - . mm) aerosols can be generated from drainage flow, in the order of per litre of air in the domestic sewage drainage system of high rises, suggesting that airborne transmission is possible from the empty u-traps and pipes leaking and containing infectious agents. the primary mode of transmission is by direct mucous membrane (eyes, nose and mouth) contact with infectious agents. the main routes are through contaminated hands or direct exposure to respiratory droplets -contact and droplet. the basic reproduction ratio of three is consistent with the main mode of transmission by droplets. however, airborne transmission of sars can indeed occur in hospital and in community housing complexes. infected cases occurred primarily in persons in close contact with ill sars patients in healthcare and household settings. transmission to casual and social contacts has occasionally occurred, especially as a result of intense exposure to sars patients eg. in lifts, in the workplace, on airlines or in taxis. transmission from children to adults is uncommon. , the attack rate for children was found to be lower than adults among quarantined close contacts in beijing ( % in children < years of age, . % in those between and years of age and . % in those aged between and years) there was no report of sars transmission in schools both in hong kong and china where the outbreak was most extensive. a cluster of nine mild paediatric patients had been reported in a private boarding school for students. all lived in the same building and ate daily meals together in the school canteen. congenital and perinatal infection have not been documented in the pregnancies reported in hong kong, nine in china and one in the usa. in hospital settings, aerosolised respiratory secretions and direct contact with patients' secretion, excreta and fomites are other amplifying events. the role of faecal-oral transmission is unknown but is probably of some significance as profuse watery diarrhoea is common and large amounts of virus are found in stool. there have been no reports of food or waterborne transmission. the role of contaminated fomites in transmission is uncertain but must not be under estimated as the virus can survive for days at room temperature on most surfaces. in one report of emergency department workers exposed to sars, nine ( . %) were infected. pneumonia developed in six, two had mild illness and one remained asymptomatic. the emergency department is a high-risk area because of its nature of trauma, heavy workload, crowded environment and lack of isolation facilities. there were at least two outbreaks in community clinic settings in hong kong. in one, a nurse was first infected by a sars patient attending the clinic and subsequently infected two other nurses, the doctor and his wife. in the second, a doctor was found to be infected on contact tracing of a household cluster of four sars cases. on further case tracing two more of the doctor's patients were found to be infected. despite great concerns, compliance to infection control precautions by community general practitioners in hong kong lagged behind their hospital counterparts - . % had not worn masks at all times, a third did not wash their hands after seeing/examining a patient and half did not wear gowns. three-quarters did not wear goggles during patient encounters, just over half insisted patients wore masks during their consultation and over doctors ( . %) who were diagnosed with suspected or probable sars had closed their clinics. however, the sample size is small and may not be representative of community doctors in hong kong. healthcare workers (hcws) working in small clinics are of particular concern because of their small size and lack of adequate decontamination facilities and a good ventilation system. ingenious designs have been developed by some to overcome this. the rate of transmition of the disease to their household contacts were . %, . % and % in non-healthcare workers, healthcare workers infected before the use of protective equipments and healthcare workers infected after the use of protective equipments respectively, indicating that use of protective equipments, adhering to infection control precautions and early quarantine were effective in stopping transmission. a similar study in singapore also found that hcws had a lower rate of household transmission but that their secondary household transmission rate was higher ( . %). phasing of illnesses is probably the reason for a much higher transmission rate in healthcare facilities. in a study of patients with probable sars reported in hong kong, . % were hospital workers, . % were members of the same household as sars patients, . % were amoy garden residents, . % were in-patients and . % were contacts of sars patients who were not family members. using multivariate analysis of : matched casecontrols of the remaining cases of undefined sources of infection, it was found that having visited mainland china, hospitals or the amoy gardens were significant risk factors. in addition, frequent mask use in public venues, frequent hand washing and disinfection of living quarters were significant protective factors. a similar study conducted in beijing on unlinked probable sars cases also showed that clinical sars was associated with visits to fever clinics. these indicate that household transmission is much less common and should allay public anxiety and panic. the main infection control measures are droplet and contact precautions. practices in paediatric and neonatal wards in hong kong that were utilised during the outbreak were well described. , it is important that strict hand hygiene and adequate decontamination be performed after each direct or potential exposure to patients and at any time that body parts are perceived to be contaminated by patients' bodily fluids. a shower after high-risk procedures and before leaving duty would have been most desirable. the employment of a 'policing nurse' had been found to be very effective in ensuring compliance to infection control precautions and procedures during the sars epidemic. while n masks have higher filtration efficiency compared with surgical masks, they have lower breathability, higher thermal stress, more discomfort and cause more fatigue. cdc recommended the use of n ( % filtration of . mm sodium chloride particles at a flow rate of l/min), the eu recommended the use of ffp or ffp masks (which had a filtering efficiency of % and % respectively, tested at l/min with . mm sodium chloride particles) and canada n respirators (filtering efficiency of . % for mono-dispersed particles of size . mm). a full face respirator with an ultra-low penetrating air filter has also been recommended for its higher efficiency, good fit and protection of the mucous membranes but the disadvantage is cost, cleaning, disinfection and maintenance. n masks should be test-fitted and the same model used whenever possible. a check fit should be performed each time one puts on the respirator and before entering the patient's room. in a study looking into factors affecting nosocomial infection in hong kong, it was found that all hcws consistently used n s or surgical masks and perceived that the inadequacy of personal protective equipment (ppe) supply, infection control training < h and inconsistent use of goggles, gowns, gloves and caps were significant independent risk factors for sars infection. the wearing of masks, gowns and goggles does pose considerable stress and fatigue to hcws. comfort and usability are other important issues to be considered. masks can also affect visibility and patient rapport. the psychological impact of masking on children has not been studied. in low-risk times and areas, surgical masks would probably be sufficient. it would be useful to have children wearing a surgical mask of appropriate size when they have respiratory symptoms, though the risk of transmission is considered to be lower than in adults. the associated discomfort may make it difficult to continue wearing the masks for a long period of time. with education, most children can be taught to put on a mask, at least when being examined or nursed and when outside the room. prescribed eye glass is not sufficient to protect against splashes. face shields should be sufficient for most pro-cedures unless excess splashes or direct coughing is expected, in these cases goggles should be worn. full face masks and hoods are more cumbersome alternatives. ppc are essential elements of infection control precautions, but which type of the available ppc provide better protection in terms of water repellency, water resistance, risk of environmental contamination, usability and comfort has not been determined. it is important to identify risk factors for non-compliance and design interventions and routines that are sustainable and practicable. in a study comparing different types of ppc available in hong kong, the use of a surgical gown in ordinary work procedures was recommended. when heavy splashes or droplets are expected, an additional plastic apron should be worn to protect the trunk. it is important that ppc should be removed when soiled. due care should be taken to avoid contamination of the environment and ppc should only be worn when needed and removed immediately on leaving isolation rooms. great care should be taken when removing ppc. lack of appropriate ppc removal procedures can lead to lapses in infection control measures. this should be done outside the patient's area and with adequate spacing to avoid cross contamination and contamination of the environment. mirrors would be helpful so that one can observe the whole procedure. one must avoid contamination of the nose, mouth and eyes while removing the cap, gown, gloves, mask and eye protectors. there are several sets of recommendations on the sequence of removing ppc. the one recommended by the national institute for infectious diseases in italy is probably the safest. the essentials are that the procedures are clear, consistent and simple to follow. the use of shoe covers is controversial and was not used in several hospitals in hong kong during the epidemics. stringent infection precautions, especially for high-risk procedures, appropriate triage and prompt isolation of potential sars patients will contribute to the control of nosocomial spread and acquisition of hcw in hospital settings. , , in a retrospective case control study of intubations, risk factors for infection included difficult intubation (or . ), extensive bagging (or . ), intubation in a general ward environment (or . ) and extensive droplet contamination. before performing high-risk pro-cedures including cpr, intubation etc, one must ensure adequate protection in appropriate and properly equipped isolation facilities. call for help if alone and choose the right technique before embarking on the procedure. the analogy of putting on your own oxygen mask before attending to others while in air flight emergencies should be remembered. neubulisation, bronchoscopy induced sputum collection and face mask ventilation should be avoided as far a possible. if medically indicated, they should be undertaken in a negative pressure room with minimal but adequate staffing. all staff should be in ppc covering the torso, arms and hands as well as eyes, nose and mouth. n s, n- s or n- s are adequate but full face masks are desirable. however, the use of powered air purifying respirators is not recommended because of risk to self and environmental contamination. the use of a face mask with a good fit and attached valved manifold may reduce the risk of transmission. no infection has been attributed to the taking of nasopharyngeal aspirate from sars patients in hong kong. when performed it should be taken in a single room while wearing full ppc. a new upper respiratory tract irrigation method has been devised to replace nasopharyngeal aspirate testing, which should be safer. the disadvantage of this method is that it cannot be used in young children. early recognition followed by prompt initiation of isolation and infection control precautions are the most important strategies for controlling sars and other emerging infectious diseases. clinical features alone cannot reliably distinguish sars from other respiratory illnesses. having an epidemiological linkage was the most consistent finding ( . %) in children infected with sars in hong kong. combining clinical findings and epidemiological linkage or clustering of cases and interpreting clinical findings with key epidemiological risk factors serves as a good framework for triage, especially for children. precise and timely information about these epidemiological risks should be provided, coupled with proper training of frontline healthcare professionals on its interpretation. a predictive model basing on a four-item clinical score of cough before or concomitant with fever, myalgia, diarrhoea and rhinorrhoea or sore throat had a % sensitivity and . % specificity of early detection of probable sars. the addition of lymphopaenia and thrombocytopaenia increased the specificity to . %. in another model, a scoring system of attributing , , , and points to the presence of independent risk factors of epidemiological link, radiographic deterioration, myalgia, lymphopaenia and elevated alt respectively, generated high- ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) and low-( - ) risk scores for sars. the sensitivity and specificity of this prediction rule in positively identifying a sars patient were . % and . % respectively. the prediction rule could be useful at the bedside. however, these studies were conducted in adult patients and would need to be validated in paediatric patients. other clinical guidance has also been developed but again is probably only applicable to the adult population. the case definition for clinical sars used by leung et al. in hong kong was: fever (rectal temperature of . c or oral temperature of c); chest radiograph (cxr) findings of pulmonary infiltrates or acute respiratory distress syndrome; and suspected or probable contact with a person under investigation for sars or exposure to a locality with suspected or documented community transmission of sars through either travel or residence within days of the onset of symptoms, as well as of the following: chills, malaise, myalgia, muscle fatigue, cough, dyspnoea, tachypnoea, hypoxia, lymphopenia, decreasing lymphocyte count, or failure to respond, in terms of fever and general well-being, to antibiotics covering the usual pathogens of community-acquired pneumonia (e.g. a broad-spectrum lactam plus a macrolide) after days of therapy. this case definition had a sensitivity and specificity of . % and . % respectively in identifying paediatric sars during the sars outbreak. while almost all reported patients with laboratory evidence of sars have radiographic evidence of pneumonia at some point during their illness, paediatric sars have non-specific radiographic features, making it difficult for radiological differentiation. a private general clinic participating in the sars-screening programme in hong kong during the sars epidemic -by using telephone triage followed by chest radiograph of cases with 'flu-like' illness, the author successfully and safely screened attendees, x-rayed patients and diagnosed one case of sars. therefore, a chest x-ray (cxr) would be a useful screening tool during outbreaks. a sars and avian influenza algorithm for early recognition and investigation of potential paediatric cases, modified from the uk health protection agency's algorithm, is suggested in the appendix. negative pressure rooms are recommended for the isolation of patients with sars. however, it should be noted that negative pressure rooms only prevent the virus from travelling outside the room and may not reduce viral load or environmental contamination inside the room. several designs such as low level suction and laminar flow have tried to reduce the viral load inside the room but the effectiveness is unproven. various devices such as portable/mobile local exhaust ventilation devices, tents and personal isolation systems have been designed and tested but the usability, risk of contamination of staff and effectiveness are still under study. , a rethink on the best design for effective infection control which also improves clinical and psychological care of patients is very much needed. no matter how good the design this cannot replace preparedness, a good clinical routine and appropriate personal protection. elaborate ventilation designs and negative pressure systems would be difficult in most clinical settings. exhaust fans and mobile local exhaust ventilation devices with hepa filters have been used in hospitals and clinics in hong kong. their efficacy has not been tested. several ingenious barrier precaution designs have been made by local medical practitioners: a torch mounted to a face shield for throat examination; cling film wrapping of telephones, keyboards and medical instrument to facilitate cleaning; and home-made air powered helmet hoods or tents for high-risk patients. these have not been tested and cannot replace hand hygiene, appropriate ppc and regular decontamination. while having adequate infection control equipment and facilities are important, overcrowding or inadequate bed/ clinic spacing or triage rooms and insufficient manpower are two major risk factors for hospital cross infection. having clear clinical guidelines and timely information are essential but it is it even more important that everyone has adequate information and proper training, practice and enforcement on infections and infection control starting in schools and in the community. panic and fear can be more harmful than the disease itself. sars and avian flu have taught us that infections are not just a problem for healthcare professionals, they involve everyone of all ages within communities throughout the world. adolescent twin sisters with severe acute respiratory syndrome a young infant with severe acute respiratory syndrome consensus document of the epidemiology of severe acute respiratory syndrome (sars) epidemiological determinants of spread of causal agent of severe acute respiratory syndrome in hong kong capturing super spreading events during the sars epidemics in hong kong and singapore severe acute respiratory syndrome and biology, air quality, physics and mechanical enginerring spreading of disease through the drainage system evidence of airborne transmission of the severe acute respiratory syndrome virus epidemiological linkage and public health implication of a cluster of sars in an extended family evaluation of control measures implemented in the severe acute respiratory syndrome outbreak in beijing sars-associated coronavirus infection in teenagers severe acute respiratory syndrome and pregnancy clinical analysis of pregnancy in second and third trimester complicated severe acute respiratory syndrome sars and pregnancy: a case report report of sars expert committee how did general practitioners protect themselves, their family and staff during the sars epidemic in hong kong? risk of transmission of sars to household contacts from infected health care workers and patients heng eh, mark a, ma ea, tan oh. secondary household transmission of sars sars transmission, risk factors, and prevention in hong kong risk factors for sars among persons without known contact with sars patients infection control for sars in a tertiary paediatric centre in hong kong infection control for sars in a tertiary neonatal centre scientific evaluation of protection, heat stress, comfort and usability of facemasks cdc public health guidance for community-level preparedness and response to sars version . supplement i: infection control in healthcare, home and community setting sars and masks sars respiratory protection: update sars transmission among hospital workers in hong kong effective personal protective clothing for health care workers attending patients with sars sars and removal of personal protective equipment current concepts: the severe acute respiratory syndrome risk factors for sars in hcws following intubation of sars patients -a retrospective multi-centre study. sars clinical management workshop a practical approach to airway management in patients with sars dispersal of respiratory droplets with open vs. closed oxygen delivery masks -implications for the transmission of severe acute respiratory syndrome conjunctivaupper respiratory tract irrigation for early diagnosis of severe acute respiratory syndrome severe acute respiratory symptom among children predictive model of diagnosing probable cases of severe acute respiratory syndrome in febrile patients with exposure risk gold standard for sars and clinical diagnosis models sars and avian influenza algorithm: recognition, investigation and initial management of potential cases. uk health protection agency severe acute respiratory syndrome: chest radiographic features in children an outcome analysis of chest x-ray examination for detecting severe acute respiratory syndrome in general practice sars busters validating air distribution design and performance controlling biohazards at the source personal isolation system key: cord- - vgo q authors: to, w.m. title: association between energy use and poor visibility in hong kong sar, china date: - - journal: energy (oxf) doi: . /j.energy. . . sha: doc_id: cord_uid: vgo q a city's reliance on energy increases when it is developed. moreover, the combustion of fossil fuels inevitably generates air pollutants including carbon dioxide, nitrogen oxides, sulfur dioxide, particulate matter, and others. combining with other anthropogenic air pollutants, visibility in many asian cities including hong kong have deteriorated rapidly in the past decades. this paper explores the relationships between energy use, meteorological factors, and change in visibility in hong kong using long-term time-series data. the total use of primary energy increased from , tj in to , , tj in while the number of hours of reduced visibility increased from h to h during the same period of time. bivariate correlations show that poor visibility was significantly associated with energy use and annual mean air temperature. multiple regression analysis indicates that the burning of aviation gasoline significantly, adversely affect visibility. results illustrate that the number of clear days in hong kong will decrease, in particular due to the increase in air traffic. urbanization forces asian cities to develop and expand rapidly. indeed, many cities have followed a similar development process, i.e. from a manufacturing-based economy in the s and s to a service-based economy in recent years. although the world development report [ ] argues that air pollution level normally rises with income per capita but it should start to decline when income per capita exceeds a threshold level, for example, particulate matter should decrease when income per capita exceeds us$ . this inverted u-shape curve is known as environmental kuznets curve [ , ] . unfortunately, this argument is not applicable to asia. for example, annual income per capita in hong kong was us$ in and reached us$ , in . however, the total mass concentration of particulate matter, i.e. ultrafine particles, pm . and pm , in fact was much higher in than that in which in turn affects visibility in hong kong [ e ] . air pollution is still one of main concerns for people living and working here [ ] . researchers reported that poor air quality was found to be significantly associated with severe respiratory and cardiovascular diseases [ ] , might cause cancers [ ] and mortality [ , ] . the impact on human health is even more severe when air pollutants are in the form of gaseous [ ] or aerosols [ , ] . in recent years, most asian cities including hong kong have been covered by haze almost continuously between october and april [ , e ] . poor visibility, an integral form of air pollution in the dry season, may cause substantial psychological and physiological pressure on people. in recognizing the close link between energy use and its impact on environment, this paper is one of the first to systematically obtain the different energy uses in the form of time-series and explore their influences on visibility in hong kong sar, china. the effects of meteorological variables on visibility are also explored. visibility here is defined as the greatest horizontal distance at which a specified object can be seen in normal daylight condition. that is not the same as vertical visibility that can be determined by measuring aerosol optical depth from satellite images [ ] . before discussing the relationships between energy use, meteorological factors, and visibility, it is necessary to gain a background on the economic development of hong kong. in fact, hong kong has developed earlier than all other cities in china and its success has been duplicated in many parts of china such as guangzhou, suzhou, shanghai, tianjin, and others. shortly after the second world war and the civil war in china, hong kong evolved as one of four asian tigers (also known as four asian dragons) along with singapore, south korea and taiwan. it was because hong kong had attracted many entrepreneurs from shanghai and a large number of migrants from guangdong. according to ho and liu [ ] , hong kong's population increased from around , in to . million in the mid of s. the population figure increased to . million in and to . million in respectively [ ] . in the s, hong kong became a light-industrial center in asia. with a large number of unskilled workers from nearby guangdong, local entrepreneurs, and rich families fled from shanghai in the s, many light-metal, plastic, toys, textile, and garment factories were established. these factories employed hundreds of thousands labors [ ] . the manufacturing sector had expanded steadily until early s under a favorable environment, i.e. relatively low rent, low transportation cost, and low labor cost because of the abundant of unskilled workers. for example, more than . million unskilled migrants found their way either legally or illegally into hong kong's labor market between and . however, as land price and labor cost increased substantially in early s, hong kong's manufacturing sector shrank rapidly and many industrialists relocated their factories to mainland china in which the "open-door policy" has been implemented since . hong kong started transforming itself to a logistic hub and its finance and service sector expanded rapidly in the s and s. after almost two decades of transformation, hong kong succeeded to change itself from a manufacturing-based city to the busiest port in the world [ ] as well as one of the world finance centers. hong kong's container terminals handled less than . million teu (twenty-foot equivalent unit) in and steadily increased to handle . million teu in [ ] [ ] . in , hong kong attracted . million visitors and percent of visitors traveled to hong kong by flights [ ] . hong kong becomes a tourist center and the world financial center in asia. in aviation, the passenger throughput increased from . million to . million while the cargo throughput increased from . thousand tonnes to . million tonnes between and [ ] . in , the number of flights arriving and departing from the hong kong international airport was , . on road surfaces, the number of vehicles increased from , in to , in [ ] . the number of private vehicles alone increased from , to , during this period. the preceding section briefly describes the economic development of hong kong. it shows that hong kong has transformed from a manufacturing-based economy to a service-based economy in the past forty years. at the same time, hong kong's population increases at an average annual growth rate between . and . percent from . million in to . million in . however, increase in population mostly comes from the net immigration rather than the number of new borne babies in hong kong [ ] . this situation is expected to prevail in the future. as there are over . million living in hong kong and hong kong welcomes over million visitors a year, their residential, social, business, and commercial activities consume a significant amount of energy [ e ]. besides, hong kong is still one of the busiest ports in the world. all road, sea and air traffic consume a large amount of oil products and gas products. table summarizes the retained import of primary energy in , , , , , , , , and respectively [ ] . it also shows the consumption of electricity e a secondary energy in those years. the amounts of fossil fuels imported were then converted into thermal unit in terms of tj by using the calorific value of each fuel. fig. shows the energy use of hong kong from to based on the annual net import of fossil fuels and the net electricity imported from shenzhen's daya bay power station in china after [ ] . it illustrated that the total energy use increases continuously except in , and . the sudden drops of energy use in these three years can be understood because as an open economy hong kong was significantly affected by the asian financial crisis in and the world financial crisis triggered by sub-prime mortgage problems in the united states in e and e . figs. and show the imported energy of each fossil fuel from to . it should be noted that aviation gasoline and kerosene are primarily consumed by aircrafts, motor gasoline by private vehicles, diesel oil by buses, trucks and industrial boilers, fuel oil by ships (and by power companies before ), lng (liquefied natural gas) by power companies after , and coal by power companies after . fig. shows the percentage of thermal unit (i.e. using tj) for oil products, gas products, and coal products from to . it illustrates that hong kong predominately used oil products before . between and , over percent of the energy use of hong kong came from oil products. heavy fuel oil was the main source of energy to generate electricity and to produce thermal energy in factories, hotels, hospitals, etc. from to , hong kong's power companies consumed a significant amount of coals to generate electricity. in order to diversify the source of primary energy and to discharge less air pollutant to the environment, the government of hong kong requested hong kong's power companies to use lng in generating around percent of electricity locally. since , a portion of electricity has been generated using lng and has been imported from shenzhen's daya bay power station. visibility is an integrative parameter that refers to the ability to see a distant object. it depends on the characteristics of the object, its surrounding, air quality and the illumination of the sight path. more specifically, it is affected by all types of particulate matter and aerosols in the atmosphere [ ] . in hong kong, the visibility readings have been recorded by the hong kong observatory at its headquarters located at the city's center [ ] . reduced visibility is defined as visibility below km when there is no fog, mist, or precipitation [ ] . the readings have been recorded based on hourly measurements using a forward scatter visibility meter. fig. shows the number of hours of reduced visibility observed at the hong kong observatory from to . fig. shows that there was no substantial change in visibility between and . however, there was an upward trend after . fig. shows the number of hours of reduced visibility observed at the same location on a monthly basis. it indicates that visibility in hong kong deteriorates; especially in autumn and winter that hong kong has been covered by haze continuously between october and april in recent years. it should be noted that the distance between the hong kong observatory located in tsim sha tsui and the old hong kong international airport (also known as kai tak airport; see fig. a ) was km. the hong kong observatory has also recorded the number of hours of reduced visibility at the hong kong international airport after it was relocated to an artificial island at chek lap kok in as shown in fig. b . the numbers of hours of reduced visibility observed at the airport on a monthly basis are shown in fig. . however, there was no visibility data at chek lap kok before . by comparing the number of hours of reduced visibility at the hong kong observatory and that at the hong kong international airport between and , the correlations, i.e. the r-values between these two sets of data were . using the annual data and . using the monthly data respectively. besides, the distance between the hong kong international airport and the hong kong observatory is km and a significant number of flights fly over the kowloon peninsula and victoria habour (see fig. b ). hence, only table import of fossil fuels (primary source of energy) in , , , , , , , the number of hours of reduced visibility at the hong kong observatory will be used to correlate with fuel uses and in multiple regression analysis because this dataset has a much longer history of forty-one years. in addition to visibility date, the hong kong observatory [ ] also published the annual mean air temperature in c, annual mean atmospheric pressure in hpa, annual mean relative humidity in percent, annual total rainfall in mm recorded at the hong kong observatory, and the annual mean wind speed in km/hr recorded at an outlying island (waglan island) of hong kong between and . the hong kong observatory [ ] also indicated that the prevailing wind direction is (ene (east-northeast)) in winter and (sw (southwest)) in summer. bivariate correlation was performed between the visibility data recorded at the hong kong observatory, the imported energy of each fossil fuel, and meteorological variables including the annual mean air temperature in c, annual mean atmospheric pressure in hpa, annual mean relative humidity in percent, annual total rainfall in mm, and the annual mean wind speed in km/hr. the analyzed results are shown in table and table . fig. and fig. show scatter diagrams between visibility and each of fossil fuel. they show that there was a very strong, significant simple linear relationship between visibility and the consumption of aviation gasoline (r ¼ . , p < . for degrees of freedom). data were scattered on the other plots with the r value ranging from . to . (p < . for degrees of freedom). fig. shows scatter diagrams between visibility and meteorological variables and trend lines. they show that only annual mean air temperature was moderately, significantly associated with visibility (r ¼ . , p < . for degrees of freedom). multiple regression analysis was then applied to identify the contribution of the consumption of fossil fuels to the number of hours of reduced visibility. all meteorological variables were also entered as independent variables to explore whether they have any effect on visibility. stepwise procedure was employed because this procedure combines both forward and backward procedures and produces the optimal solution [ ] . at the first step, the independent variable, i.e. a fuel type or meteorological variable, with the largest correlation with visibility entered the equation. in the next step, another variable was selected according to the highest partial correlation. if this variable passed the stepping method criteria, i.e. where visib is the number of hours of reduced visibility, c is a constant, a i is the unstandardized coefficient of the ith fuel, fuel i is the quantity of the ith type of fuel in gj, b j is the unstandardized coefficient of the jth meteorological variable, and meteorological j is the quantity of the jth type of meteorological variables. after running the multiple regression analysis in spss . software, only one independent variable, i.e. aviation gasoline and kerosene, was entered in the stepwise procedure. multiple regression analyses, using the forward selection method and the backward elimination method, produced the same result. the final form of the regression equation is given as below. ( ). fig. shows the comparison between the number of hours of reduced visibility using equation ( ) and the actual data. it also provides the band of predicted values using the % confidence intervals of c and a. fig. indicates that there was a positive, moderate, significant relationship between annual mean air temperature and visibility for the period e while the relationships between visibility and other meteorological variables were weak and non-significant. it was because an increase in the combustion of aviation gasoline and kerosene increased the number of hours of reduced visibility while an increase in the combustion of fossil fuels including oil products, coal and natural gas increased local annual mean air temperature. in fact, the increase in local annual mean air temperature due to the combustion of fossil fuels was also reported by stone [ ] in large us cities. the monthly data of mean air temperature, mean atmospheric pressure, mean relative humidity, total rainfall recorded at the hong kong observatory and mean wind speed recorded at waglan table bivariate correlation between visibility and the imported energy of each fossil fuel. motor gasoline gas oil, diesel oil and naphtha fuel oil liquefied petroleum gas and natural gas coal products visibility . *** . *** . *** . *** . *** . *** (i) the total sample size is . (ii) * for p < . ; ** for p < . ; *** for p < . . bivariate correlation between visibility and each meteorological variable. annual mean temperature annual mean atmospheric pressure annual mean relative humidity annual total rainfall annual mean wind speed visibility . ** À . À . À . À . (i) the total sample size is . (ii) * for p < . ; ** for p < . ; *** for p < . . fig. . scattered diagrams between visibility and fossil fuels including aviation gasoline, motor gasoline, and diesel oil. fig. . scattered diagrams between visibility and fossil fuels including fuel oil, lpg/ng, and coal products. island of hong kong were also collected [ ] . correlation analyses indicated that monthly mean air temperature was lower, monthly mean atmospheric pressure was higher, and the amount of monthly total rainfall was much less during the winter months from december to march. pair-wise correlation was performed between visibility and each of meteorological variables on monthly basis for each year. the value of average pair-wise correlation was then determined using equation ( ). where r is the average pair-wise correlation [ ] , n is the total number of years i.e. from to , x i is the number of hours of reduced visibility on monthly basis and y i is the corresponding value of a meteorological parameter on monthly basis for a particular year. table shows the values of average pair-wise correlation and standard deviation between visibility and each meteorological variable. results show that only monthly mean air temperature was negatively, moderately, significantly associated with visibility because the r value must be greater than . (p < . ) for degrees of freedom. in other words, the number of hours of reduced visibility was associated with lower air temperature, supporting that severe haze was observed during the winter months from december to march in hong kong. this paper is one of the first to employ long-term time-series data in investigating the relationships between poor visibility (i.e. the integral form of air pollution in the dry season), energy use, and meteorological variables in hong kong sar, china. visibility in hong kong has deteriorated continuously in the past decades while the net import of fossil fuel energy has increased by times. multiple regression analysis shows that the burning of aviation gasoline and kerosene significantly adversely affects visibility in hong kong, and burning of lpg and lng moderately affects visibility. the effect of burning of other fossil fuels and meteorological factors on visibility on annual basis was not statistically significant. nevertheless, correlation analysis between monthly visibility readings and monthly records of meteorological variables indicates that poor visibility was in general associated with lower air temperature i.e. the winter months in hong kong with higher mean atmospheric pressure and less or no rainfall. the findings of this study is consistent with the research works conducted recently in the united states and england [ e ] in which a significant amount (in terms of the number concentrations) of ultrafine particles were observed due to jet departures, jet landing, jet taxi and idle. aircraft operations also produce a large amount of no x (nitrogen oxides) and voc (volatile organic compound) [ , ] . in fact, it has been known that for an aircraft operating over on km range approximately % of the emissions are produced during the take-off/landing cycle [ , ] . as there are over a thousand commercial aircrafts departing and landing at the hong kong international airport per day as reported by the china daily [ ] , many aircrafts taxi above hong kong and produce a significant amount of particulate matter in low troposphere. the aged particles with a mode diameter of nm [ ] will collide and grow to form the accumulation mode ultrafine particles. these accumulation mode particles will stay and disperse in low troposphere. they block and scatter the reflected visible light with a wavelength between nm and nm, causing a substantial reduction in visibility. lpg is one of the main types of fuel gas used in hong kong for water heating in domestic, commercial, and industrial buildings. it is also used as a fuel by nearly all taxis and over percent of public light buses. the consumption of lpg increases significantly during the autumn and winter, hence, the amount of fine particulate matter emitted from burning of lpg from about . million domestic, commercial and industrial users in hong kong also increases. lng is primarily used by local power companies for producing electricity. it is a form of 'cleaner energy' and can reduce the total amount of particulate matter emitted from power plants by reducing the amount of coal burnt. visibility is an indicator of air quality [ , ] . poor visibility can adversely affect human physiologically as well as psychologically [ , ] . it has primarily caused by the burning of aviation gasoline and kerosene in hong kong sar, china. according to the report from the hong kong civil aviation department, the total number of flights landing and departing from hong kong increased from , in to , in . recently, there are more than a thousand flights landing and departing from hong kong per day. it is no doubt that air transport plays an important role in local economic development such as hong kong e one of the world finance centers, a regional tourism center, and the world's logistic hub. the government of hong kong projects that traffic at the hong kong international airport will increase to , in and planned to build the third runway to cope with the increased demand. however, it is expected that the number of hours of reduced visibility will increase to around by the year (using equation ( ) and assuming the fuel consumption to be linearly proportional to the number of flights). it is almost impossible to hong kong to have a "clear sky" in future, especially between october and april, a period without high humidity, rains and storms to flush out ultrafine particulate pollutants. past research [ ] shows that aircraft operations would have no discernible elevation of -averaged pm . (or pm ) mass, but highly elevated total suspended particulates, especially in the form of ultrafine particles. hence, it is necessary for the government of hong kong to monitor ultrafine particles and pm . both in terms of the number and mass concentrations, rather than relying on the pm mass concentration measurements in the existing air quality monitoring networks. in addition, some of the monitoring stations shall be located at a higher level from the ground, rather than the existing ones that are located at the ground levels and/or the roadsides. the correlation and multiple regression analyses show that visibility would be moderately affected by burning of lpg and lng. world development report : development and the environment environmental kuznets curve hypothesis: a survey investigating the energy-environmental kuznets curve visibility degradation across hong kong: its components and their relative contributions water-soluble aerosol and visibility degradation in hong kong during autumn and early winter daily visibility and mortality: assessment of health benefits from improved visibility in hong kong associations between daily mortalities from respiratory and cardiovascular diseases and air pollution in hong kong, china emission of carcinogenic components from commercial kitchens in hong kong particle emission factors during cooking activities size distributions of the aerosols emitted from commercial cooking processes visibility trends in six megacities in china e fuel life cycle emissions for electricity consumption in the world's gaming center e macao sar scientific background of haze and air pollution in hong kong the growth pattern and fuel life cycle analysis of the electricity consumption of hong kong clear sky visibility has decreased over land globally from to international labour migration: the case of hong kong kong in figures . hong kong census and statistics department hong kong as an environment for industry the transition from freight consolidation to logistics: the case of hong kong economic analysis and business facilitation unit, hong kong financial secretary's office a graphic guide on hong kong's development: e . hong kong census and statistics department the annual traffic census . hong kong transport department climate and residential electricity consumption in hong kong a study of domestic energy use patterns in hong kong seasonal variations in residential and commercial sector electricity consumption in hong kong ); quantity of retained imports of oil products. hong kong statistics and census department considerations in the measurement of visibility number of hours of reduced visibility observed at the hong kong observatory (from to a study of visibility trends in hong kong summary of meteorological and tidal observations (from to evaluation of plant availability of rare earth elements in soils by chemical fractionation and multiple regression analysis urban sprawl and air quality in large us cities improved estimates of correlation coefficients and their impact on optimum portfolios detecting and quantifying aircraft and other on-airport contributions to ambient nitrogen oxides in the vicinity of a large international airport aircraft emission impacts in a neighborhood adjacent to a general aviation airport in southern california the los angeles international airport as a source of ultrafine particles and other pollutants to nearby communities quantification of the impact of aircraft traffic emissions on tropospheric ozone over paris area aircraft emissions at turkish airports gas turbine theory hong kong's daily flights hit new high seasonal characteristics of haze observed by continuous visibility monitoring in the urban atmosphere of kwangju impaired visibility: the air pollution people see psychological reactions to air pollution zero energy buildings and sustainable development implications e a review predicting daylight illuminance and solar irradiance on vertical surfaces based on classified standard skies renewable energy strategies for sustainable development the application of dynamic modelling techniques to the grid-connected pv (photovoltaic) systems large-scale integration of wind power into the existing chinese energy system as the consumption of lpg increases substantially during the autumn and winter, the amount of fine particulate matter emitted from gas-fired boilers and heaters in buildings increases. it is suggested that more energy-efficiency buildings shall be designed [ , ] and the use of renewable energy [ ] such as photovoltaic [ ] and wind power [ ] should be explored. key: cord- -jnmogy s authors: yang, lin; ma, stefan; chen, ping yan; he, jian feng; chan, king pan; chow, angela; ou, chun quan; deng, ai ping; hedley, anthony j.; wong, chit ming; peiris, j.s. malik title: influenza associated mortality in the subtropics and tropics: results from three asian cities date: - - journal: vaccine doi: . /j.vaccine. . . sha: doc_id: cord_uid: jnmogy s influenza has been well documented to significantly contribute to winter increase of mortality in the temperate countries, but its severity in the subtropics and tropics was not recognized until recently and geographical variations of disease burden in these regions remain poorly understood. in this study, we applied a standardized modeling strategy to the mortality and virology data from three asian cities: subtropical guangzhou and hong kong, and tropical singapore, to estimate the disease burden of influenza in these cities. we found that influenza was associated with . , . and . deaths per , population in guangzhou, hong kong and singapore, respectively. the annual rates of excess deaths in the elders were estimated highest in guangzhou and lowest in singapore. the excess death rate attributable to a/h n subtype was found slightly higher than the rates attributable to a/h n during the study period of – based on the data from hong kong and guangzhou. our study revealed a geographical variation in the disease burden of influenza in these subtropical and tropical cities. these results highlight a need to explore the determinants for severity of seasonal influenza. influenza is one of the respiratory pathogens that can cause serious health problems in both mortality and morbidity worldwide. however, unspecific presenting symptoms of influenza, absence of timely laboratory tests in clinical practice and frequent secondary bacterial pneumonia make it difficult to estimate the disease burden of influenza directly from the clinical diagnosed cases [ , ] . it is therefore necessary to assess influenza associated excess mortality or hospitalization by statistical modeling and use the estimate as a measurement for severity of influenza epidemics [ ] . some studies reported that the disease burden of influenza was nearly equivalent across some temperate countries [ ] , but others noticed that abbreviations: ili, influenza-like illness; icd, international classification of diseases; crd, cardiorespiratory diseases; p&i, pneumonia and influenza; copd, chronic obstructive pulmonary diseases; ihd, ischemic heart diseases. effects of influenza occasionally exhibited disparities between geographical areas even in the same influenza season [ ] . it has been proposed that socioeconomic factors and various circulating virus strains could play an important role in determining the severity of influenza epidemics [ ] [ ] [ ] . some environmental factors that are critical for survival and transmission of viruses, such as temperature and humidity, could also be involved as effect modifiers [ ] . however, geographical variations in influenza associated disease burden in the tropics and subtropics have not been explored. a recent large-scale phylogenetic study postulated that novel influenza viruses first emerge in the tropics and subsequently spread into the temperate when environmental factors favor virus transmissions [ ] . particularly, east and southeast asian countries are proposed as the potential reservoirs for dormant influenza viruses, although the mechanism remains unclear [ ] . unfortunately, there are few disease burden studies in this region to provide the evidence for or against the postulation, largely due to a lack of data from well-designed long-standing surveillance. this situation was further complicated by the unpredictable influenza seasonality in these regions. in this study we applied a standardized modeling strategy to three metropolitan cities in east and southeast asia: guangzhou, hong kong and singapore, all of which have well-organized surveillance networks for influenza for several years. guangzhou and hong kong, both located at southern china, share a similar subtropical climate with a mean temperature around • c, but the latter is more economically developed with a higher gdp per capita of $ , in hong kong as compared with that of $ in guangzhou in [ , ] . singapore is a tropical city with a higher mean temperature of . • c than guangzhou and hong kong. the socioeconomic level of singapore is comparable to hong kong, with a gdp per capita of $ , in [ ] . the difference and similarity between these cities, in terms of socioeconomic status and environmental factors, provide us a good opportunity to explore the factors that may affect the disparity or similarity across geographical areas. the influenza virology data in guangzhou, hong kong and singapore during - were obtained from the guang dong provincial center for disease control and prevention (gdcdc), the hong kong department of health (dh) and the singapore ministry of health (moh), respectively. the nasopharyngeal aspirate specimens were collected from the outpatients or inpatients presenting influenza-like illness (ili) symptoms of fever (≥ • c), cough or sore throat and then were tested for influenza by direct immunofluorescence or cell culture. positive samples were later typed or subtyped into a/h n , a/h n and b by haemagglutination inhibition (hi) test with strain-specific antiserum provided by the world health organization (who). mortality data for each city were obtained from hong kong census and statistics department (coded according to the international classification of diseases tenth revision, icd- ), guangzhou department of health (coded in icd- ) and singapore registry of births and deaths (coded in icd- ), respectively. we aggregated the weekly numbers of deaths with underlying cause of cardiorespiratory diseases (crd, icd- - ; icd- i -i , j -j ), pneumonia and influenza (p&i, icd- - ; icd- j -j ), chronic obstructive pulmonary diseases (copd, icd- - ; icd- j -j ), ischemic heart diseases (ihd, icd- - ; icd- i -i ) and all causes (icd- - ; icd- a -t ). two age groups were considered: all-ages and the elders aged years or over. we obtained the weekly mean temperature and humidity for three cities, from the national meteorological information center in china, hong kong observatory and singapore national environment agency, respectively. we fitted a poisson regression model to weekly numbers of mortality with the aim to assess the percentage of excess mortality associated with increased influenza activity in the population, as described in our previous studies [ , ] . briefly, long-term trends and seasonal patterns of mortality counts, as well as weekly average temperature and relative humidity, were added as confounders into the core models with their natural cubic spline smoothing functions. both temperature and humidity have been found to affect influenza virus transmission [ ] and also been associated with mortality in previous studies [ , ] . a typical form of core model is where yt denotes the death numbers at week t; ns(t), ns(temp t ) and ns(humd t ) denote the natural spline smoothing functions of time, temperature and relative humidity, respectively. auto-regressive terms in the residuals may be added to remove significant autocorrelations of residuals in first four weeks, so that time varying confounding could be adequately controlled. the weekly proportions of specimens positive for specific influenza types/subtypes (named as influenza proportions, flu t ) were simultaneously entered into the core model, to estimate influenza effects: the annual effects of influenza on mortality for each year were measured by excess mortality associated with influenza, which is defined as the sum of differences between the observed and expected death numbers when influenza proportions were assumed to be zero during that entire year [ ] . the % confidence intervals (ci) for estimates were derived by bootstrapping the scaled pearson residuals for times. we further derived the excess death rates associated with influenza per , population to render influenza effects comparable between cities. the percentage of excess deaths was calculated as the excess deaths divided by the total number of observed deaths. all the analyses were performed using the mgcv package of r software (version . . .) [ ] . two subtropical cities guangzhou and hong kong shared similar meteorological conditions, while the tropical city singapore tended to be hotter and more humid with much less variations in both temperature and humidity (table ) . among the three cities, hong kong had the largest population, while singapore had the youngest ( table ). the crude mortality rate of guangzhou was slightly higher than that of hong kong and singapore, respectively. more than % of deaths were in the or older age group in guangzhou and hong kong, whereas this number was only % in singapore. crd was the major cause of death in all three cities, but p&i mortality in guangzhou and copd in singapore was the lowest among the three cities ( table ) . the proportion of specimens positive for influenza a or b in singapore had an average of . %, which was lower than that in guangzhou and hong kong ( . % and . %, respectively) ( table ). this could be due to less stringent diagnosis criteria adopted by singapore for recruitment of patients into its surveillance network, using the case definition of acute respiratory illness instead of ili. influenza seasonality was similar between hong kong and guangzhou, but the winter peak was less pronounced in the latter. there were no clear epidemic periods in singapore, despite one sharp spike around june of (fig. ) influenza was significantly (p < . ) associated with all-cause mortality as well as with underlying cause of crd, p&i, copd and ihd for the all-ages group in all three cities, with the exceptions of copd in guangzhou and singapore, and ihd in singapore (table ) . during the study period of - , hong kong had the highest percentages of excess deaths associated with influenza among the three cities, with the only exception of ihd deaths. for the all-ages group, hong kong had the highest excess deaths for all causes and for underlying causes of p&i and copd, whereas guangzhou had the highest excess deaths due to crd and ihd. the excess death rates for the old population were highest in guangzhou for all-cause and crd death. note: ci, confidence interval; crd, cardiorespiratory diseases; p&i, pneumonia and influenza; copd, chronic obstructive pulmonary diseases; ihd, ischemic heart diseases. the annual death rates attributable to influenza revealed the greatest disease burden of influenza in the year for guangzhou and singapore, but in for hong kong. the year with the lowest disease burden was for hong kong and singapore, and for guangzhou (fig. ) . in guangzhou, an annual rate of . between the two types of influenza virus, influenza a accounted for the majority of excess deaths in all three cities (data not shown). as the denominator of subtype proportion of singapore was not comparable with that of the other two cities, we only estimated deaths attributable to influenza a subtypes, a/h n and a/h n , in guangzhou and hong kong. comparison between the two subtypes showed that a/h n accounted for slightly more excess deaths in the all-ages group for all the disease categories under study in both guangzhou and hong kong (fig. ) . this pattern was also observed for the + age group. to our best knowledge, this is the first comparative study between asian subtropical and tropical cities for influenza disease burden. the surveillance networks for influenza in guangzhou, hong kong and singapore were established under the who global influenza surveillance network [ ] , which allowed us to estimate the disease burdens in a standardized procedure and to compare across cities. here we adopted the poisson regression models to assess the age-disease specific excess mortality rates associated with influenza. allowing for flexible adjustment of seasonal factors, this poisson model has been widely used in many other disease burdens studies and is recommended for the subtropical and tropical regions with unpredictable influenza seasonality in a recently published who guideline [ ] [ ] [ ] [ ] [ ] . our recent validation study using an empirical dataset of laboratory confirmed influenza cases demonstrated that this model was able to provide reliable estimates for disease burden of influenza [ ] . although this approach requires sufficient long-standing year-round surveillance data, such data have become available in many subtropical and tropical regions in recent years. our study may serve as a good example for the disease burden studies across these regions. two previous studies found that the influenza associated mortality rates were nearly equivalent between hong kong and singapore, and singapore even had a higher excess rate for the older population [ , ] . however, these results need careful interpretation as these two studies differed in terms of statistical models, data aggregation and study periods covered. the present study adopted a standardized modeling approach to show that the overall influenza burden was comparable between the two subtropical cities guangzhou and hong kong, but lower in the tropical singapore. this geographical disparity was particularly evident in the elders, with the highest excess mortality rates associated with influenza found in guangzhou, which has a smaller proportion of old population than hong kong but is the least developed among the three cities. cohen et al. also found the mortality impact of seasonal influenza was higher in the elders of south africa than in those of the united states and this difference did not diminish after adjustment for age structures [ ] . together with our findings, it seems that the socioeconomic factors may associate with the mortality burden of influenza, particularly for the elders. another fig. . annual excess all-cause mortality rates associated with influenza (per , population) between guangzhou, hong kong and singapore, all-ages group. important factor that needs to be considered in interpreting our results is the different underlying susceptibility of population to severe outcomes of influenza infection across three cities. for example, the lower overall impact of influenza in singapore may not be due to its tropical climate, but partially due to its younger age structure. this heterogeneity of susceptibility could possibly been adjusted for by calculating age standardized excess mortality rates for each city, as the elders tend to be more fragile and have a higher mortality risk attributable to influenza. however, it is difficult to obtain reliable estimates for younger age groups due to small numbers of deaths. a future study with a longer study period shall be able to provide estimates with proper adjustment for age structures. singapore had the lowest disease burden from influenza among three cities, although fewer people in singapore had received influenza vaccination annually. in , doses of influenza vaccine were distributed for every total population in singapore [ ] , but a corresponding vaccination rate doses/ total population was reported in hong kong [ ] and doses/ total population in guangzhou (he jf, unpublished data). during - the annual distribution doses of seasonal influenza vaccines in singapore were around doses/ total population, less than half of those in hong kong [ ] . however, the effectiveness of influenza vaccines is largely complicated by age structure of population and also by various levels of herd immunity. moreover, the severity of infections could be aggravated by the environmental factors favoring virus transmission, such as air pollution [ ] . it has been widely cited that the disease burden of influenza, in terms of excess p&i mortality and hospitalization, tended to be higher in the a/h n dominant seasons than those with a/h n and b as the dominant virus strains [ ] [ ] [ ] . a/h n is believed to transmit more efficiently in human population than a/h n and antigenic drifts occurred more frequently in this subtype [ , ] . surprisingly, we found that the disease burden attributable to a/h n was slightly lower than the burden attributable to a/h n in guangzhou and hong kong. we noticed that after the outbreak of severe acute respiratory syndrome (sars) viruses in , all the three cities observed dramatically increased vaccination rates for influenza [ ] . we compared the excess mortality attributable to each subtype during the pre-sars period of - in hong kong, and the results showed that h n were associated with significantly more deaths than h n (data not shown). although a new strain a/california/ / -like gradually became prevalent in the late year of , it did not dramatically increase the mortality risks associated with influenza according to our results. some studies have shown that this novel strain mainly attacked the young adults and the vaccine recommended for the northern hemisphere during the - season was still able to provide crossprotection against it [ , ] . as a result, those susceptible people (the elders and chronic patients) might have still been benefited from increased vaccination and exempted from deaths. however, the disease burden of a/h n may have long been neglected, probably owing to its less frequent antigenic drifts compared to a/h n in the human community. recent experimental studies have found that seasonal h n strains can replicate as efficiently as pandemic h n and avian h n strains in ex vivo-infected lung tissues [ , ] . further experimental studies on virulence of different subtypes circulating in - may help to solve this mystery. more epidemiology studies with longer time series data from different climates are also needed to compare the relative severity of a/h n and a/h n strains. our study has potential caveats. firstly, these three cities vary in the organization of their influenza surveillance networks. most specimens in hong kong were mainly from the inpatients and therefore more severe cases of influenza infections were recruited into the surveillance. the sentinel doctors of guangzhou were all from the outpatient sectors, and the virology data exhibited greater variation than the other two cities due to limited numbers of samples taken each week. singapore had the lowest positive rates of influenza specimens, probably due to the fact this city included a mixture of samples from both inpatient and outpatient settings. nonetheless, we standardized the comparison procedure by using the age-specific excess mortality rate as measurement for influenza effects, which could at least partially exclude the bias introduced by different surveillance systems in these cities. secondly, although we carefully controlled for the confounding seasonal factors by building core models a priori, it is possible that there are still many unmeasured confounding factors. moreover, to what extent such confounding factors should be adjusted for was subject to personal judgement and over-fitting of core models cannot be completely avoided, as revealed by the negative estimates in some disease categories. thirdly, all three cities in this study might be more socioeconomically developed than the rest of asian cities; therefore, extra caution is needed to extrapolate our findings to the other cities/countries. last but not least, we did not quantify the statistical significance of differences between the city specific estimates, because they were derived from different models. but their overlapping confidence intervals suggest that the differences might not be statistically significant. in conclusion, by using a standardized modeling approach, we found a geographical disparity in mortality rates attributable to influenza, which could be partially explained by socioeconomic factors and age structure. in future, a multinational study comprising regions across temperate, subtropical and tropical countries like our present study could provide more information about mechanisms and severity of seasonal influenza and thereby help the policy makers to refine their regional specific control measures against influenza. clinical signs and symptoms predicting influenza infection influenza: old and new threats the impact of influenza epidemics on mortality: introducing a severity index influenza epidemics in the united states influenza epidemic, england and wales, canada, and the united states multinational impact of the hong kong influenza pandemic: evidence for a smoldering pandemic estimation of potential global pandemic influenza mortality on the basis of vital registry data from the - pandemic: a quantitative analysis influenza virus transmission is dependent on relative humidity and temperature the genomic and epidemiological dynamics of human influenza a virus the global circulation of seasonal influenza a (h n ) viruses per capita gdp at current market prices influenza-associated mortality in hong kong seasonal effects of influenza on mortality in a subtropical city the effect of weather on respiratory and cardiovascular deaths in u.s cities heat stress and public health: a critical review r: a language and environment for statistical computing the effect of universal influenza immunization on mortality and health care use the association of respiratory syncytial virus infection and influenza with emergency admissions for respiratory disease in london: an analysis of routine surveillance data influenza-related hospitalisation and death in australians aged years and older hospitalization attributable to influenza and other viral respiratory illnesses in canadian children world health organization. a practical guide for designing and conducting influenza disease burden studies validation of statistical models for estimating hospitalization associated with influenza and other respiratory viruses influenza-associated deaths in tropical singapore elevated influenza-related excess mortality in south african elderly individuals the macroepidemiology of influenza vaccination study group. the macroepidemiology of influenza vaccination in countries the international federation of pharmaceutical manufacturers and associations influenza vaccine supply (ifpma ivs) task force. influenza vaccine distribution in countries modification by influenza on health effects of air pollution in hong kong the impact of influenza epidemics on hospitalizations mortality associated with influenza and respiratory syncytial virus in the united states influenza-associated hospitalizations in the united states synchrony, waves, and spatial hierarchies in the spread of influenza effectiveness of vaccine against medical consultation due to laboratory-confirmed influenza: results from a sentinel physician pilot project in british columbia assessment of the effectiveness of the - influenza vaccine among children and adults-colorado tropism and innate host responses of the pandemic h n influenza virus in ex vivo and in vitro cultures of human conjunctiva and respiratory tract tropism of avian influenza a (h n ) in the upper and lower respiratory tract supplementary data associated with this article can be found, in the online version, at doi: . /j.vaccine. . . . key: cord- - ebj gi authors: demmler, gail j; ligon, b.lee title: severe acute respiratory syndrome (sars): a review of the history, epidemiology, prevention, and concerns for the future date: - - journal: seminars in pediatric infectious diseases doi: . /s - ( ) - sha: doc_id: cord_uid: ebj gi abstract during the first part of , the world experienced the first epidemic of the st century with the emergence of a new and readily transmissible disease. the disease, severe acute respiratory syndrome (sars), spread quickly and caused numerous deaths, as well as public panic. this article provides a brief review of the initial history of the epidemiology, as well as of the clinical definition, occurrence in the pediatric population, etiology, prevention, drug studies, and considerations for the future. the first report of the new disease, given the name "severe acute respiratory syndrome" (sars), was received by who on february from the chinese ministry of health, which documented that cases and deaths had occurred in the guangdon province. two days later, on february , a -year-old physician who had treated patients for what was thought to be atypical pneumonia checked into a -star hotel in hong kong and was given a room on the th floor. he had begun having symptoms five days earlier, but upon arrival in hong kong, he felt well enough to go sightseeing and shopping with his brother-in-law. however, the next day, he sought urgent care and was admitted with respiratory failure to the intensive care unit of a hospital. he unwittingly had transmitted the disease to at least other guests and visitors to the th floor, with the result that the disease was spread quickly worldwide. on march , an individual who earlier had visited the th floor of the hong kong hotel was admitted to the prince of wales hospital in hong kong with respiratory symptoms for which he was treated for days with a jet nebulizer four times a day. one of the guests at the same hotel, a -year-old chinese-american businessman, became ill with high fever, dry cough, myalgia, and mild sore throat and was admitted on february to the french hospital in hanoi. he later was evacuated to hong kong, where he died. two days later, dr. carlo urbani, a who official in vietnam, reported an alarming number of patients being treated at the french hospital for atypical pneumonia. , by march , secondary probable sars cases were identified among healthcare workers in hanoi, and at the urging of dr. urbani and his colleagues, vietnam closed the hospital to new patients and visitors on march . most of the hospital's staff remained in the hospital; some of them fell ill while others watched their colleagues sicken and die. prompt action taken by a steering committee led by the health minister was instrumental in containing the disease. by may , the hanoi french hospital had transferred the last of its patients to another hospital and was being thoroughly disinfected. another hotel guest staying on the th floor proved to be the index case of sars in singapore. a previously healthy -year-old woman of chinese ethnicity, she had been on a vacation to hong kong from february to february . she developed fever and a headache on february and a dry cough on february . on march , she was admitted to a hospital in singapore, where over the course of several days, she infected at least other people. no further transmission from this patient was observed after strict infection control measures (use of n masks, gown, gloves, and handwashing before and after patient contact) were implemented. , as of may , cases of sars had been diagnosed in singapore and patients had died. on march , yet another guest on the th floor of the hotel, a -year-old toronto woman, died from sars; subsequently member of her family were admitted to the hospital. , , the patient and her husband had traveled to hong kong from february to february to visit relatives. two days after returning home, the woman, who had a history of type diabetes and coronary heart disease, developed fever, anorexia, myalgia, a sore throat, and mild nonproductive cough. three days later, her doctor examined her and found pharyngeal erythema but no other abnormalities; she was prescribed an oral antibiotic and was sent home. two days later, she noticed the development of increasing cough with dyspnea, and on march , days after the onset of her illness, she died at home. soon, cases of sars were occurring in taiwan. the first suspected cases were diagnosed in a couple on march . the man had traveled in february to the guangdong province and to hong kong. on march , a taiwanese resident of hong kong's amoy gardens flew to taiwan and took a train to taichung to celebrate the traditional festival qing ming. his brother became taiwan's first sars fatality. a fellow passenger on the train also was affected. the number of cases began to increase steadily during the last weeks of april. on april , the taiwanese government imposed a mandatory -day quarantine on all incoming travelers from china, hong kong, singapore, macau, and toronto. as of may , , cases of sars had been diagnosed in taiwan, and patients had died. by the time the cases occurred in taiwan, reports had begun flooding into who from different parts of the world. on march , staff members of the private french hospital in hanoi were ill with an acute respiratory syndrome, and a who team arrived to provide support. by march , at least hospital personnel in the hanoi hospital and at the prince of wales hospital in hong kong were ill with an unidentified acute respiratory syndrome. , on march , who issued a global alert concerning the spread of a severe atypical pneumonia with unknown etiol-ogy. three days later, with more instances of the disease being reported, who decided on the basis of factors (table ) to increase the level of the global alert issued on march . several criteria, namely clinical, epidemiologic, and laboratory, have been established by the cdc as criteria for the definition of sars (table ) . a "probable" case is defined as one that "meets the clinical criteria for severe respiratory illness of unknown etiology and epidemiologic criteria for exposure; laboratory criteria confirmed, negative, or undetermined." a "suspect" case is that "meets the clinical criteria for moderate respiratory illness of unknown etiology, and epidemiologic criteria for exposure; laboratory criteria confirmed, negative, or undetermined." a case can be excluded as being either suspect or probable if an alternative diagnosis can fully explain the illness or the case was reported on the basis of contact with a suspected index case that subsequently was excluded as a case of sars, provided other possible epidemiologic exposure criteria are not present. sars appears to take a less aggressive clinical course in younger children in comparison to that seen in adults and teenagers. until april , children younger than years of age, accounted for only percent of all cases reported in hong kong. the reason for this low percentage is unclear. the first publication on sars in the pediatric population comes from hon and colleagues. because most data available were on adults, they decided to report on their experience in treating children at the prince of wales and princess margaret hospitals in hong kong. between march and , , they admitted children with suspected cases of sars. all children satisfied the who case definition for sars, had been in close contact with infected adults, and had fever that lasted for a median duration of . the causative agent and the potential for spread were still unknown. . the outbreaks appeared to pose a great risk to health care workers, family members, and other close contacts of patients. . none of the different antibiotics and antivirals that had been tried empirically seemed to have an effect. . although the numbers still were relatively small, the clinical course had progressed rapidly to respiratory failure, requiring intensive care, and many previously healthy patients had died. . the disease had spread from its initial focus in asia to north america and europe. days. the authors noted distinct patterns of clinical presentation: teenage patients presented with symptoms of malaise, myalgia, chill, and rigor similar to those of adults, whereas the younger children presented primarily with cough and runny nose; none had chills, rigor, or myalgia. the younger children also experienced much shorter and milder clinical courses, and radiological changes were milder and generally resolved more quickly than in the teenagers. although all of the patients had clinically important lymphopenia, the teenagers suffered more severe cases. all patients were treated with a regimen of ribavirin and steroids similar to that used in adults sars patients. a detailed table listing the ages, sex, clinical features, laboratory findings, radiological findings, and treatment and outcome is available in the article, which also can be accessed at http://image.thelancet.com/extras/o let web.pdf. using the global outbreak alert and response network (goarn), a who mechanism launched in to link together existing networks with extensive data resources, expertise, and skills, who initiated an emergency plan that called for arenas of attack, on land and in the air. the land initiative involved sending teams of experts and specialized protective equipment for infection control to countries requesting such assistance. the land attack involved establishing a "virtual" network of leading laboratories connected by a shared secure website and daily teleconferences; this network worked around the clock to identify the causative agent of sars and to develop a robust and reliable diagnostic test. the results from the establishment of the laboratory network were the conclusive identification of the causative agent of sars only a month later and the complete sequencing of its rna shortly thereafter (see below). immediately after the incidence of sars was recognized, researchers were at work attempting to identify the etiological agent. shortly thereafter, perhaps at record speed, the culprit was identified. on april , , the first publications, initially published on-line, reported the identification of a novel coronavirus. drosten and colleagues reported that they had isolated "a novel coronavirus" in cell culture and had obtained a sequence nucleotides in length using polymerase chain reaction (pcr)-based random amplification. on the basis of the obtained sequence, they established conventional and real-time pcr assays for specific and sensitive detection of the novel virus; the assays detected a variety of clinical specimens from patients with sars but not from controls. high concentrations (up to million molecules per milliliter) were found in sputum, and viral rna also was detected at extremely low concentrations in plasma during the acute phase and in faces during the late convalescent phase. the authors suggested that the novel coronavirus might have a role in causing sars. the other report came from ksiazek and associates, who reported that no classic respiratory or bacterial respiratory pathogen was identified consistently, but that a novel coronavirus was isolated from patients who met the case definition of sars. cytopathic features were noted microscopically in vero e cells that had been inoculated with a throat-swab speciment. electron microscopic examination revealed ultrastructural features characteristic of coronaviruses. reactivity with group i coronavirus polyclonal antibodies was revealed using immunohistochemical and immunofluorescence staining. the authors used consensus coronavirus primers designed to amplify a fragment of the polymerase gene by reverse transcription-polymerase chain reaction (rt-pcr) to obtain a sequence that clearly identified the isolate as a unique coronavirus only distantly • travel (including transit in an airport) within days of onset of symptoms to an area with current or previously documented or suspected community transmission of sars (see table) , or • close contact within days of onset of symptoms with a person known or suspected to have sars laboratory criteria • confirmed ⅙ detection of antibody to sars-cov in specimens obtained during acute illness or Ͼ days after illness onset, or ⅙ detection of sars-cov rna by rt-pcr confirmed by a second pcr assay, by using a second aliquot of the specimen and a different set of pcr primers, or ⅙ isolation of sars-cov. • negative ⅙ absence of antibody to sars-cov in convalescent serum obtained Ͼ days after symptom onset. • undetermined ⅙ laboratory testing either not performed or incomplete. related to coronaviruses previously sequenced. using specific diagnostic rt-pcr primers, they were able to identify several identical nucleotide sequences in patients from several locations. indirect fluorescent antibody tests and enzyme-linked immunosorbent assays made with the new coronavirus isolate demonstrated a virus-specific serologic response. the authors suggested the name urbani sarsassociated coronavirus as the nomenclature for this virus in honor of one of the authors on the paper, dr. carlo urbani, who had died during the investigation of the initial sars epidemic. efforts have been underway at various institutions to assess potential anti-sars-cov agents in vitro. ribavirin has been used clinically in sars patients, but it seems to lack the in vitro efficacy. kanchan and colleagues have suggested the viral main proteinase (m pro , also called cl pro ), which controls the activities of the coronavirus replication complex, as an attractive target for therapy. they determined crystal structures for human coronavirus (strain e) m pro and for an inhibitor complex of porcine coronavirus [transmissible gastroenteritis virus (tgev)] m pro and constructed a homology model for sars coronavirus (sars-cov) m pro . they noted that the structures reveal a remarkable degree of conservation of the substrate-binding sites, which is further supported by recombinant sars-cov m pro -mediated cleavage of a tgev m pro substrate. molecular modeling suggests that available rhinovirus c pro inhibitors may be modified to make them useful for treating sars. this particular epidemic alone has resulted in untold costs beyond the immediate health concerns. by may , the estimated costs in the far east alone were approximately $ billion. other concerns involved the worldwide public panic, with its emotional and psychological tolls; the social instability that occurred in the hardest hit areas; the loss of jobs by some government officials; the closures of hospitals, schools, and borders; and even the deployment in singapore of military forces to assist in contact tracing and enforcement of quarantines. who and researchers from various areas have noted the need to consider the potential for future outbreaks and to be prepared to contain them. who warns that sars presents a particular threat for several reasons, among which are ( ) no vaccine has been developed yet and ( ) treatment and containment measures require isolation and quarantine. furthermore, because the virus comes from a family of viruses notorious for their frequent mutations, it has the potential for future outbreaks and poses problems for development of a vaccine. epidemiology and pathogenesis remain poorly understood, diagnostic tests have important limitations that allow for contagious individuals to slip through safety nets and infect more individuals, and the disease shows a disturbing concentration among previously healthy hospital staff. who also has identified numerous positive lessons that have been learned from the sars experience so far ( table ) . lessons of caution for future incidents also have been identified and include the need to impress upon all countries the responsibility for containing the emergence of any new infectious disease, particularly in a "world where all national borders are porous when confronted by a microbial threat." other studies point to other measures, such as the use of reduction of contact between infectious individuals and others, quarantine standards adopted with regard to contacts of cases, and the rapid hospitalization of patients, as contributors to the success achieved in containing the diseases. despite the rapid identification of the causative agent of sars and the containment of the disease, several the appeal by vietnam, where who assistance was requested quickly and fully supported deficiencies and concerns also have been identified by who (table ). perhaps the most important lesson is the need to recognize that, in a global economy such as exists today, attempts to conceal cases of an infectious disease for fear of social, economic, political, or other consequences are merely stopgap measures that have dire results: loss of credibility before the international community, negative domestic economic impact, damage to health and economies of other countries, loss of lives, public panic, and the potential for the offending country's own territory to spiral out of control. in addition to the many lessons that have been learned from the sars epidemic numerous questions remain. because this new coronavirus is sufficiently transmissible to cause a large epidemic, it requires that good, basic public health measures be in place. questions remain about the accuracy of case reports, especially because in many instances the data are poor and instances of underdiagnosis and misdiagnosis are almost inevitable during an outbreak of a new disease. other questions concern the evident heterogeneity in transmission, especially in light of the extreme instances of transmission in which single individuals apparently infected as many as others. yet another concern is whether global eradication of sars can be established. table . concerns identified by who as result of sars . inadequate surge capacity in hospitals and public health systems . healthcare providers themselves being the victims of the disease . shortage of expert staff to coordinate national and global responses to a rapidly evolving public health emergency . in some cases, the need for hasty construction of new facilities; in other cases, hospitals being closed . the power of poorly understood infectious diseases to incite widespread public anxiety and fear, social unease, economic losses, and unwarranted discrimination severe acute respiratory syndrome (sars): status of the outbreak and lessons for the immediate future. world health organization, geneva, communicable disease surveillance and response who: cumulative number of reported probably cases of sars a cluster of cases of severe acute respiratory syndrome in hong kong sarsreference online text how vietnam halted sars and saved the life of a nurse severe acute respiratory syndrome (sars) in singapore: clinical features of index patient and initial contacts identification of severe acute respiratory syndrome in canada a major outbreak of severe acute respiratory syndrome in hong kong updated interim us case definition for severe acute respiratory syndrome (sars) clinical presentations and outcome of severe respiratory syndrome in children identification of a novel coronavirus in patients with severe acute respiratory syndrome a novel coronavirus associated with severe respiratory syndrome coronavirus main proteinase ( cl pro ) structure: basis for design of anti-sars drugs modeling the sars epidemic key: cord- -qb jlt f authors: kai hou, wai; hall, brian j.; canetti, daphna; lau, kam man; ng, sin man; hobfoll, stevan e. title: threat to democracy: physical and mental health impact of democracy movement in hong kong date: - - journal: j affect disord doi: . /j.jad. . . sha: doc_id: cord_uid: qb jlt f background: this study examined the prevalence and critical predictors of anxiety and depressive symptoms and self-rated health, following the umbrella movement in hong kong. methods: random digit dialing recruited a population-representative sample of chinese hong kong citizens (mean age= . years; % female) in the first two weeks of february . respondents gave their informed consent and reported personal, social, and economic resource loss since the umbrella movement (conservation of resources-evaluation), current anxiety symptoms (state-trait anxiety inventory) and depressive symptoms (patient health questionnaire- ), and self-rated health ( =very good, =very bad). results: a total of . % ( % ci= . , . ) respondents reported moderate/severe anxiety symptoms and . % ( % ci= . , . ) reported moderate/severe depressive symptoms; . % ( % ci= . , . ) reported “poor” or “very poor” health. multivariable regressions revealed that personal and social resource loss was associated with higher anxiety and depressive symptoms and greater odds of “very poor” health (adjusted odds ratios/incidence rate ratios= – %), independent of lower education level and income and being unmarried. limitations: this study was cross-sectional in nature and thus could not determine causality from the associations between resource loss and outcome variables. second, the telephone survey relied on self-reports; response bias and social desirability could influence respondents' answers and discount data validity. third, potential confounders such as preexisting mental and physical health issues and concurrent predictors like exposure to the umbrella movement were not assessed. conclusions: this is one of the first studies following any recent political movement (e.g., the arab spring) to quantify distress and the associated correlates of distress among affected citizens. perceived psychosocial resource losses were critical predictors of poor outcomes. arab spring). the conservation of resources (cor) theory suggests that resource loss is the central mechanism driving adaptation to stress. resources broadly include those personal, social, and material resources that we centrally value and are often divided between internal and external resources (hobfoll, ; hou and wan, ) . internal or personal resources consist of entities that are possessed by the self and can be mobilized on one's own such as sense of self-worth, sense of control over one's life, and optimism (diener et al., ) . external resources consist of entities that are embedded within the physical environment or interpersonal interactions, such as social relationships, money, and employment (house et al., ) . a summary of media reports revealed that people supported the movement because they foresaw threat of resource loss including abolishment of the rule of law and deprivation of freedom (e.g., speech and press) (bertolini, ; cheung, ) . use of tear gas and pepper spray, physical assaults to suppress the protestors, and cases of selective law enforcement (e.g., non-action to some violence against the protestors by anti-protestors) further heightened people's perceived threat of potential political oppression if there was no universal suffrage in . the umbrella movement could be understood as an investment of internal or external resources to create passageways for political resources, i.e., democracy and universal suffrage, among some hong kong citizens (hobfoll, ) . a recent study focusing on the arab spring in north africa and the middle east has shown that the timing of social protest is linked to a particular increase in food prices (lagi et al., ) . this suggests that the inability to provide for oneself and family, the lack of self-sufficiency, and the fear of economic loss and deprivation are also some of the prime drivers of social action. perhaps the most potent example of the consequences of the depletion of internal and external resources was the actions of mohammed bouazizi, a street vendor, in tunisia on december , . he, after having had his wares confiscated by municipal workers, set fire to himself, thus setting in motion the events that led to the arab spring (dupont and passy, ) . despite the possibility that social protests could create resource passageways, they also have the power of depleting internal and external resources, which has central impact on the citizens' psychological and physical well-being. preventing depletion of these resources is key for maintaining healthy functioning (hobfoll, ; hobfoll et al., ; hou and lam, ; hou et al., a hou et al., , b hou et al., , . in cairo, egypt, citizens who were injured in political demonstrations reported higher levels of psychiatric symptoms than patients who experienced physical trauma from other causes. in both groups (n¼ each), similar levels of perceived external control over life (e.g., other important persons, fate, chance) were reported and predicted higher symptoms, suggesting the adverse impact of possible depletion of personal resources (papanikolaou et al., ) . there is limited study of the psychological and health impact of political movements with reference to resource loss (de la sablonnière et al., ) . prior studies reported the association between resource loss and psychological functioning during major social upheaval. among russian women in the midst of russian economic transition, loss of economic resources (e.g., housing, stable employment) predicted depressive symptoms both directly and indirectly through a reduction of a personal sense of mastery over their life situations (shteyn et al., ) . among israeli settlers (n¼ ) who had faced terrorism and armed conflict and were subsequently evacuated by force from gaza, a place that provided them with economic compensation and ideological and religious meaning, loss of economic resources (e.g., economic suffering, property damage) predicted clinically significant depressive symptoms, whereas loss of personal and social resources (e.g., confidence in coping with major crises, social intimacy) predicted both depressive and posttraumatic stress symptoms (hall et al., ) . a recent population-representative study conducted among adults living in the palestinian authority found that the most salient predictor of new cases of posttraumatic stress disorder was social resource loss (hall et al., ) . a study among east and west germans found that loss of social and economic resources (e.g., partner relationships, standard of living) between and after the fall of the berlin wall predicted lower life satisfaction and higher negative affect (westerhof and keyes, ) . this is the first study to investigate physical and mental health following social/political movement in the greater china region, and one of the first following any recent political movement (e.g., the arab spring), to quantify distress and the associated resource loss and correlates of distress. the goals of this study were to describe the prevalence of anxiety and depressive symptoms and self-rated health, and investigate the associations of personal, social, and economic resource loss and preexisting socioeconomic resources with anxiety and depressive symptoms and self-rated health during the immediate period following the umbrella movement in hong kong. we hypothesize the following: hypothesis . : following the umbrella movement, prevalence of anxiety and depressive symptoms and poor self-rated health will be higher than published population norms and typical of what studies find for populations under significant stress. hypothesis . : loss of personal, social, and economic resources will be positively associated with anxiety and depressive symptoms and inversely associated with self-rated health. hypothesis . : possessing preexisting socioeconomic resources will be inversely associated with anxiety and depressive symptoms and positively associated with self-rated health. upon obtaining the ethics committee's approval from the hong kong institute of education, respondent recruitment and telephone interviews were conducted by the centre for communication and public opinion survey of the chinese university of hong kong, an experienced survey institute, during the first two weeks of february . a computer-assisted telephone interview system was used. a database of the telephone numbers from the latest residential telephone directories was created by erasing the last two digits and appending two random digits to each number. this method allowed new or unlisted telephone numbers to be included. a person was considered eligible if he/she was ( ) a hong kong chinese citizen, ( ) years of age or above, and ( ) cantonese-speaking. if multiple household members were eligible after successful contact, the one with the closest birthday to the interview date was selected. five attempts were made to a number that were "no answer," "busy," or "eligible unavailable" (i.e., willing to participate but unavailable) while no further attempts were made following two refusals. voluntariness of participation without incentives was emphasized. oral informed consent was obtained at the onset of interview. all interviews were conducted in cantonese. among the total , telephone numbers attempted, , ( . %) of them were ineligible based on the inclusion criteria; , ( . %) were unconfirmed eligible, meaning that they were never reached and their status as eligible or not was never evaluated. among the ( . %) eligible numbers, interviews were completed for ( . %), whereas ( . %) indicated refusal and ( . %) indicated unavailability. the sampling error was within . % at % confidence level. a response rate of % was recorded along with a cooperation rate of . %. the respondents ranged in age between and years (m ¼ . , sd ¼ . , median ¼ . ); ( . %) were female and ( . %) were married. forty-nine ( . %) respondents reported receiving no formal education, ( . %) primary education, ( . %) secondary education, and ( . %) tertiary education or above. one hundred fifty-six ( . %) reported an average monthly household income less than hk$ , , ( . %) reported $ , -$ , , ( . %) reported $ , -$ , , ( . %) reported $ , -$ , , ( . %) reported $ , -$ , , ( . %) reported $ , -$ , , ( . %) reported an income exceeding $ , (us$ e hk $ . ); ( . %) did not report income. a total of ( . %) reported full-time employment, ( . %) a part-time employment, ( %) being unemployed, and the remainder being students (n ¼ ; . %), housewives (n ¼ ; . %), or retired (n ¼ ; . %). respondents lived in hong kong for an average of . years (sd ¼ . , range¼ - years, median ¼ years). the current sample resembled the population in terms of sex and age group distributions (census and statistics department, ). a standardized proforma was used to obtain demographic information including age in years, sex, marital status (i.e., single, married/cohabited, divorced/separated, widowed), education level, employment status, monthly household income, and years of residence in hong kong. the chinese version of the -item state version of the state-trait anxiety inventory (stai- ) was used to assess anxiety symptoms (marteau and bekker, ; shek, ) . respondents rated the frequency of six emotional states, namely calm, tense, upset, relaxed, content, and worried, during the past two weeks on a -point scale ( ¼ not at all, ¼somewhat, ¼ moderately, ¼very much). scores on three positive-worded items were reverse coded. the total summed scores were prorated (i.e., multiplied by / ), following scale scoring conventions, in order to obtain scores that were comparable with those from the full -item stai (range¼ - ) (marteau and bekker, ) . a cutoff score of was used to indicate moderate to severe symptoms (knight et al., ; leung et al., ; spielberger, ) . alpha was . , for the current administration. the chinese version of the -item patient health questionnaire (phq- ; yeung et al., ) was used to assess depressive symptoms during the past two weeks on a -point scale ( ¼not at all, ¼on several days, ¼on more than half of the days, ¼nearly every day). higher scores indicated higher depressive symptoms (range¼ - ). the chinese version has demonstrated high internal consistency among chinese (α . ; yeung et al., ; nan et al., ) . to indicate severity of depressive symptoms, the following cutoff scores were adopted based on previous population-based studies among chinese (nan et al., ) : minimal ¼ - , mild ¼ - , moderate¼ - , moderately severe¼ - , and severe z . in this study, alpha was . . self-rated health status was assessed using a commonly used single item indicator scored as ¼very good, ¼good, ¼ poor, and ¼very poor. brief self-reported health assessments are robust and valid predictors of mortality (desalvo et al., ). the conservation of resources evaluation (cor-e; hobfoll and lilly, ) was forward and back-translated into chinese (table ) to assess actual loss of personal, social, and economic resources (three items each) since the start of the umbrella movement. personal resource loss items assessed optimism and personal control over the future: "sense of optimism," "feeling that my future success depends on me," and "feeling that i have control over my life." social resource loss items assessed interpersonal intimacy: "intimacy with one or more family members," "intimacy with at least one friend," and "bonding with at least one family member/friend on social media e.g., facebook, twitter, line, whatsapp, etc." economic resource loss items assessed financial status: "adequate income," "financial assets (stocks, property, etc.)," and "financial stability." respondents rated each item on a -point scale ( ¼not at all/not applicable, ¼ loss to a small degree, ¼loss to a moderate degree, ¼ loss to a considerable degree, ¼loss to a great degree). loss of each type of resource was calculated by summing across the three items (range¼ - ). alphas for the personal, social, and economic resource loss subscales were . , . , and . , respectively. the study data was weighted by sex, age, and education level based on the data of population census in hong kong (census and statistics department, ). to allow for the best use of the available data, the small portion of missing data (no more than . % on any study variable) were replaced by multiple imputations. to address hypothesis , the first part of the analyses aimed to report the estimated prevalence of anxiety and depressive symptoms and self-rated health with % confidence intervals ( % ci). to address hypotheses and , the second part of the analyses aimed to investigate the associations of resource loss and preexisting socioeconomic resources with the risk of reporting anxiety and depressive symptoms and poor self-rated health. different regression models were used for the three outcomes. multivariable regression was conducted for anxiety symptoms as a continuous outcome; ordinal logistic regression was conducted for self-rated health as an ordinal outcome. to determine whether our data on depressive symptoms best matched a poisson or negative binomial distribution, an exploratory zero-inflated poisson regression was conducted, followed by a zero-inflated negative binomial regression without the assumption of equal mean and variance of the depressive symptoms. the negative binomial model would be used if its goodness-of-fit tests indicated smaller values of the akaike's information criterion (aic) and bayesian information criterion (bic) fit indices and a ratio of pearson chisquare and degree of freedom closer to . compared with poisson model. adjusted odds ratios/incidence rate ratios (aor/ airr) with % ci were reported to indicate the independent association of each resource loss or demographic with an outcome while adjusting for potential confounders. in all regression models, loss of resources was recoded into high ( sd of the mean), medium (within sd of the mean), and low (o sd of the mean). education level ( ¼primary education or below, ¼secondary education, and ¼tertiary education), employment status ( ¼unemployed, ¼ dependent, and ¼ employed), and marital status (married ¼ /unmarried ¼ ) were also recoded. based on the median household income of hk $ , (census and statistics department, ), income level was recoded into ¼ less than hk$ , , ¼hk$ , -$ , , ¼ hk$ , -$ , , ¼hk$ , -$ , , and ¼hk $ , or above. years of residence were adjusted by dividing it by age; higher values indicated longer lifetime residence in hong kong (range¼ - ). education level, household income, employment status, and being married were considered proxies for preexisting socioeconomic resources (hobfoll, ) . all analyses were performed using spss (version ; spss inc., chicago, il). to address hypothesis , using a cutoff score of for stai, a total of . % ( % ci ¼ . , . ) of the respondents reported moderate to severe levels of anxiety symptoms. using a cutoff score of for phq- (kroenke et al., ; nan et al., ) the results of the regression analyses are summarized in table (hypotheses and ) . multivariable regression demonstrated that respondents with medium and high personal resource losses reported % and % higher in anxiety symptoms, respectively (medium: aor ¼ . , % ci ¼ . , . , p o. ; high: table prevalence of anxiety and depressive symptoms and self-rated health. depressive symptoms self-rated health the ordinal logistic regression revealed that respondents with high personal resource loss reported % higher in the odds of poorer self-rated health (aor ¼ . , % ci ¼ . , . , p ¼. ). older age, primary education or below, and being unmarried were associated with %, %, and % higher in the odds of poorer selfrated health, respectively (age: aor ¼ . , % ci ¼ . , . , p¼ . ; r primary education: aor ¼ . , % ci ¼ . , . , p¼ . ; unmarried: aor ¼ . , % ci ¼ . , . , p ¼. ). the odds of poorer self-rated health were % lower among men compared with women (aor¼. , % ci ¼ . , . , p¼ . ), and for one unit increase in lifetime residence in hong kong, the odds of poorer self-rated health were % lower (aor¼ . , % ci ¼. , . , p ¼. ). social or political unrest has the power of depleting internal and external resources and contributes to poorer mental and physical health (hall et al., ; hobfoll, hobfoll, , , but very few studies to date have reported the psychological and health impact table adjusted odds ratios/incidence rate ratios for higher anxiety and depressive symptoms and poorer self-rated health by personal, social, and economic resource loss, socioeconomic resources (education, income, employment status, and marital status), and other demographics. note. aor¼ adjusted odds ratio and airr ¼ adjusted incidence rate ratio. of political movements around the world. two months after the conclusion of the umbrella movement in hong kong, this study found an alarming . % of moderate to severe levels of anxiety symptoms and almost % of moderate to severe depressive symptoms among respondents, though the majority ( %) did not report "poor/very poor" self-rated health (hypothesis ). pertinent to hypothesis , multivariable regressions showed that loss of personal resources was positively associated with the odds of higher anxiety symptoms and poorer self-rated health, whereas loss of both personal and social resources was positively associated table chinese version of selected items on conservation of resources-evaluation (cor-e). with the odds of higher depressive symptoms. proxies of lower socioeconomic resources including primary education or below, lower household income, and being unmarried were also positively associated with the odds of higher anxiety/depressive symptoms and poorer self-rated health (hypothesis ). age and lifetime residence in hong kong (i.e., total years/age), on the other hand, were inversely associated with the odds of higher anxiety and depressive symptoms. the significance of the umbrella movement on hong kong citizens' mental health became obvious when we compared the present data with those in previous population-based studies among chinese. the most representative data on self-reported anxiety symptoms to date was obtained from hong kong residents at multiple timepoints following the outbreak of severe acute respiratory syndrome (sars) in (leung et al., ) . sars generated considerable fear and psychological distress among people in the affected regions (hawryluck et al., ; koh et al., ; leung et al., ) . compared with the data that was obtained among hong kong chinese two to three months after the outbreak of sars (leung et al., ) , higher anxiety symptoms were reported by almost all age groups in this study (table ). in a similar vein, compared with the phq- data on depressive symptoms among a population-based sample of , hong kong chinese (nan et al., ) , higher percentage of depressive symptoms were observed in mild (n ¼ , . %), moderate (n ¼ , . %), moderately severe (n ¼ , . %), and severe (n ¼ , . %) levels in the present sample (table ). on the other hand, we found that only . % of the respondents reported "poor/ very poor" self-rated health, which was obviously low compared with population-based data among chinese in hong kong ( . %, n ¼ ; wang et al., jia et al., ), and singapore ( . %, n ¼ ; lim et al., ) . this could be because umbrella movement was short and nonviolent. it is likely that physical health impact is greater in more prolonged and violent cases like yemen and syria. our findings underscore the impact of resource loss on psychological functioning during a period of social upheaval. personal resource loss since the start of the umbrella movement was associated with higher levels of anxiety and depressive symptoms and the odds of poorer self-rated health by - %. a populationbased survey during the umbrella movement (n ¼ ) reported that % of the respondents expressed a pessimistic view over the future of hong kong, % expressed disagreement with the current chief executive election proposal (i.e., candidates are selected by a nomination committee consisting of members), and % agreed that the government should back down to resolve the situation (the chinese university of hong kong, ). the umbrella movement did not lead to any concrete political outcomes, while the hong kong government has refused to make changes to (leung et al., ) after sars outbreak in hong kong and the scores that were obtained in the present study. leung et al. ( ) present study m ( % ci) m ( % ci) notes. the total summed stai scores were prorated, following the scale scoring convention, in order to obtain scores that were comparable with those from the full -item stai (range¼ - ). m¼ mean; ci ¼ confidence interval. scores on phq- that were obtained in a previous normative study (nan et al., ) and the scores that were obtained in the present study. minimal ( the current chief executive election proposal. worries of respondents could have been manifested in lower levels of optimism and a sense of mastery over one's life and future success. if the current election proposal is implemented or hong kong citizens do not adjust their expectation, ongoing personal resource loss could demonstrate increased health impact. social resource loss was associated with increased odds of depressive symptoms by %, supplementing previous evidence on its predictive utility in posttraumatic stress disorder (ptsd). like recovery from ptsd, recovery from depressed mood could depend heavily on prevention of social resource loss or restoration of lost social connections following social-political upheaval (hall et al., ) . social resource loss could be attributed to everyday political discussions with close social partners. the umbrella movement encouraged spirited debate and polarized opinions that may have disrupted social harmony. discussions could increase the probability of agreement among close social partners (morey et al., ) , but "universal suffrage" was made ambiguous by granting hong kong citizens the right to vote and the right to be elected but not the right to nominate candidates. because of the ambiguity of the issue, the chance of political disagreement increases, while strong ties encourage confrontation of political disagreement that could inadvertently reduce relationship strength and intimacy (huckfeldt et al., ) . economic resource loss was not associated with anxiety, depression, and self-rated health, while proxies of lower preexisting socioeconomic resources including lower education level and household income and being unmarried were associated with higher anxiety and depressive symptoms and poorer self-rated health. age and lifetime residence in hong kong were associated with lower anxiety and depressive symptoms, whereas lifetime residence was also associated with better self-rated health. these socioeconomic resources take time to accumulate within the local setting and thus were not easily shaken by the umbrella movement. on the other hand, economic resource loss indicates specific loss of adequate income, financial assets, and financial stability since the start of the movement. the findings extend the wellestablished link between socioeconomic status and physical and mental health to political psychology (adler et al., ) . in milder cases of pro-democracy movements, longstanding socioeconomic resources, not momentary loss of income or financial stability, could have a stronger association with mental and physical health. a number of limitations warrant attention. first, because this study was cross-sectional in nature, we cannot determine causality from the associations between resource loss and outcome variables. psychological distress could indeed increase resource loss, which then reciprocally enhances psychological distress, forming a loss spiral during political violence (heath et al., ; hall et al., ) . second, the telephone survey relied on self-reports. response bias and social desirability could influence respondents' answers and discount data validity especially on psychiatric symptoms. however, phone-based structured clinical interviews have been found to be a valid method for detecting and monitoring psychiatric symptoms (hobfoll et al., ; muskens et al., ) . third, potential confounders such as preexisting mental and physical health issues and concurrent predictors like exposure to the umbrella movement were not assessed. unmeasured confounders could dilute the associations between predictors and outcomes, whereas concurrent predictors like exposure to the movement could accelerate different resource losses. in conclusion, our findings provide an evidence base for future studies on psychological impact of social uprisings in arab spring or elsewhere in the world. one common feature across pro-democracy movements around the world is protestors' willingness to invest internal and external resources in order to resist oppressive rule and create passageways for social and political resources (hobfoll, ; pearlman, ) . in more successful cases of prodemocracy movements, like those of tunisia, jordan, and morocco, protests were relatively shorter and probably caused less psychological and health problems to the peoples. resource loss among these peoples is down regulated by the positive political outcomes and opportunity of resource gain. meanwhile, in many places with pro-democracy movements, such as syria (united nations, ) , protests are on-going and yet to result in political success or stability, bringing about more resource loss than opportunity of gain to the peoples. depletion of resources could have a more significant negative impact on the peoples' physical and mental health. socioeconomic status and health: the challenge of the gradient population census-summary results the melancholy of hong kong dramatic social change: a social psychological perspective mortality prediction with a single general self-rated health question personality, culture, and subjective wellbeing: emotional and cognitive evaluations of life the arab spring or how to explain those revolutionary episodes a longitudinal investigation of changes in social resources associated with psychological distress among kurdish torture survivors living in northern iraq the psychological impact of impending forced settler disengagement in gaza: trauma and posttraumatic growth loss of social resources predicts incident posttraumatic stress disorder during ongoing political violence within the palestinian authority sars control and psychological effects of quarantine reciprocal relationships between resource loss and psychological distress following exposure to political violence: an empirical investigation of cor theory's loss spirals stress, culture, and community: the psychology and philosophy of stress conservation of resources and disaster in cultural context: the caravans and passageways for resources resource conservation as a strategy for community psychology are community studies of trauma's impact exaggerated? a study among jews and palestinians trajectories of resilience, resistance, and distress during ongoing terrorism: the case of jews and arabs in israel resilience in the year after cancer diagnosis: a crosslagged panel analysis of the reciprocity between psychological distress and well-being does change in positive affect mediate and/or moderate the impact of symptom distress on psychological adjustment after cancer diagnosis? a prospective analysis resource loss, resource gain, and psychological resilience and dysfunction following cancer diagnosis: a growth mixture modeling approach changes in positive affect and mindfulness predict changes in cortisol response and psychiatric symptoms: a latent change score modelling approach perceived control mediates the prospective impact of relationship quality in the year after colorectal cancer diagnosis social relationships and health disagreement, ambivalence, and engagement: the political consequences of heterogeneous networks difference of the associations between self-rated health and demographic characteristics, lifestyle, and psychosocial work environment between two types of chinese worksite some norms and reliability data for the state-trait anxiety inventory and the zung self-rating depression scale risk perception and impact of severe acute respiratory syndrome (sars) on work and personal lives of healthcare workers in singapore: what can we learn? the phq- the food crises and political instability in north africa and the middle east longitudinal assessment of community psychobehavioral responses during and after the outbreak of severe acute respiratory syndrome in hong kong the impact of community psychological responses on outbreak control for severe acute respiratory syndrome in hong kong gender, ethnicity, health behaviour & self-rated health in singapore the development of a six-item short-form of the state scale of the spielberger state-trait anxiety inventory (stai) the "who" matters: types of interpersonal relationships and avoidance of political disagreement psychiatric diagnosis by telephone: is it an opportunity effects of depressive symptoms and family satisfaction on health related quality of life: the hong kong family study relationship of locus of control, psychological distress, and trauma exposure in groups impacted by intense political conflict in egypt emotions and the microfoundations of the arab uprisings reliability and factorial structure of the chinese version of the state-trait anxiety inventory the impact of the russian transition on psychosocial resources and psychological distress manual for the state-trait anxiety inventory public opinion and political development in hong kong statement by the secretary-general on fulfilling our collective responsibility on syria health information seeking partially mediated the association between socioeconomic status and self-rated health among hong kong chinese after the fall of the berlin wall: perceptions and consequences of stability and change among middle aged and older east-and west-germans validation of the patient health questionnaire- for depression screening among chinese americans this research was supported by internal research grant, the hong kong institute of education, hong kong (research grants council direct allocation; ref: rg / - . the authors declare that they have no conflict of interest.author disclosure dr. wai-kai hou: formulation of the conceptual framework; statistical analysis; write-up. dr. brian j. hall: comments on the conceptual framework and the discussions of the findings; planning of statistical analysis. dr. daphna canetti: formulation of the conceptual framework; ideas on the discussions of the findings. miss kam man lau and miss sin man ng: assistance in statistical analysis and preparation of the manuscript. prof. stevan e. hobfoll: formulation of the conceptual framework; statistical analysis; write-up. all authors have approved the final article. the funding source was not involved in any stages of the research. key: cord- -nuhrd z authors: hung, kevin k. c.; mark, carman k. m.; yeung, may p. s.; chan, emily y. y.; graham, colin a. title: the role of the hotel industry in the response to emerging epidemics: a case study of sars in and h n swine flu in in hong kong date: - - journal: global health doi: . /s - - - sha: doc_id: cord_uid: nuhrd z background: the global travel and tourism industry has been rapidly expanding in the past decades. the traditional focus on border screening, and by airline and cruise industries may be inadequate due to the incubation period of an infectious disease. this case study highlights the potential role of the hotel industry in epidemic preparedness and response. methods: this case study focuses on the epidemic outbreaks of sars in and h n swine flu in in hong kong, and the subsequent guidelines published by the health authority in relation to the hotel industry in hong kong which provide the backbone for discussion. results: the metropole hotel hastened the international spread of the sars outbreak by the index case infecting visitors from singapore, vietnam, canada as well as local people via close contact with the index case and the environmental contamination. the one-week quarantine of more than guests and staff at the metropark hotel during the h n swine flu exposed gaps in the partnership with the hotel industry. the subsequent guidelines for the hotel industry from the centre of health protection focused largely on the maintenance of hygiene within the hotel premises. conclusion: positive collaborations may bring about effective preparedness across the health and the tourism sectors for future epidemics. regular hygiene surveillance at hotel facilities, and developing coordination mechanism for impending epidemics on the use of screening, swift reporting and isolation of infected persons may help mitigate the impact of future events. preparedness and contingency plans for infectious disease control for the hotel industry requires continuous engagement and dialogue. the global travel and tourism industry has expanded rapidly in recent years. the global number of international tourist arrivals increased from approximately million in to million in [ ] . the ever greater numbers present enormous challenges to the entire global community for epidemic preparedness and control. the increasing complexity of frequent international travel opens an ideal route for local outbreaks of infectious disease to becoming global pandemics. the health and wellbeing of travellers warrants appropriate consultation and treatment in its own right, but in the case of infectious diseases of major public health concern, it is important to address the public health aspects of their illness as patients are also disease carriers promoting the spread of infectious disease on a potentially global scale. the international health regulations (ihr) ( ) form one of the few legally binding instruments of the world health organisation (who). the purpose and the scope of ihr ( ) are "to prevent, protect against, control and provide a public health response to the international spread of disease in ways that are commensurate with and restricted to public health risks, and which avoid unnecessary interference with international traffic and trade" [ ] . most of the existing research in travel medicine and the current guidelines for international health authorities emphasise the role of the air-travel industry in tracking and thus containing the potential international spread of infectious disease. for instance, the who guideline on international travel and health highlights the role of airlines as well as shipping companies, together with that of tour operators and travel agents in limiting the spread of infectious disease across borders [ ] . similarly, the centres for disease control and prevention (cdc) guidelines focus on the airline and cruise industries [ ] . the role of the other important sector in tourism, namely the hotel industry, have been less clearly defined and discussed. this case study will use the example of the metropole hotel in hong kong in the international spread of severe acute respiratory syndrome (sars) in , and the effect of the government mandated quarantine of the metropark hotel during the swine flu in hong kong. sars was caused by the sars-associated coronavirus, with the primary mode of transmission being direct mucous membrane contact with infectious respiratory droplets [ , ] . it had a basic reproduction number of approximately , and the spread was mainly to those with close contact in health care and household settings. the first cases were identified in guangdong province of china in november , and a number of natural reservoirs have been found including civet cats and bats. incubation period ranged from to days [ ] . the overall case fatality ratio was . % worldwide, with deaths resulting from pneumonia and subsequent respiratory failure. the travel industry contributed to the speed of the spread of this unknown disease at that time, particularly within the metropole hotel as it was the first site for global dissemination of the virus [ ] . sars subsequently caused deaths in countries, with the disease spreading to cover five continents [ ] . this case vividly illustrates how a local outbreak can rapidly evolve into a global pandemic. the h n swine flu pandemic in was caused by the a(h n ) pdm influenza virus [ ] . this strain containing genes from pig, bird and human influenza viruses has never been reported before , and the outbreak was first identified in march in mexico and the united states. it was estimated that between , and , deaths resulted globally, with % in people younger than years old from respiratory and cardiovascular influenza related complications. the h n virus infection mortality was estimated to be . - . % of the world's population, much lower than the previous . % during the pandemic and the - % of the pandemic [ ] . the first imported case in hong kong was tested positive for swine influenza on the may [ ] . this has led to the subsequent quarantine of all guests and staff at the metropark hotel for week. hotels can be a critical component in the evolution of a local outbreak into a global pandemic, and an initial contact point of the import of an impending global pandemic. the aim of this paper is to highlight the role of hotel in the spread of epidemic, and discuss control measures that can be implemented. this case study focuses on the epidemic outbreaks of sars in and h n swine flu in in hong kong. secondary information was extracted from the literature search and the grey literature looking for published official reports, statements, policy papers, field reports and guidelines for further discussion on the role of the hotel industry on the epidemics. public health principles of disaster response were used to provide the backbone for discussion. medline was used to identify research articles published between january and december in the english language, to answer these specific questions: . what factors in the hotel setting contributed to international spread of sars; . the decision making and implementation of hotel quarantine during swine flu, and the impact of the hotel quarantine. any study design regarding aspects on timelines of sequence of events, environmental sampling and contamination, evaluation of hotel related interventions, modelling of interventions were included. studies not meeting the above inclusion criteria or answering the research questions was excluded. the the search identified records from medline of which five were relevant (references [ , [ ] [ ] [ ] [ ] ), and an additional records were identified through other sources and the grey literature. a medical professor from guangzhou in china arrived in hong kong on february and checked into a room on the ninth floor of the metropole hotel in kowloon [ ] . during his stay, he infected at least seven other guests and visitors staying on the ninth floor of the hotel including three visitors from singapore, one visitor from vietnam, two visitors from canada and a local individual [ ] . on march , the singapore ministry of health reported to the hong kong department of health that three patients who presented with pneumonia were admitted to hospital after returning to singapore from hong kong. they had all stayed in the metropole hotel. during the conversation, laboratory investigations were pending and there was not sufficient evidence to suggest that their illnesses had been related to the metropole hotel [ ] . on march , the who issued a global alert about unusual cases of an acute respiratory syndrome. on march , the index case for the significant outbreak at the prince of wales hospital was identified. it was not until march , after multiple enquiries, the patient revealed that he had visited the metropole hotel around that period as a visitor but not a guest [ ] . on the same day, the hong kong department of health reported the chain of transmission of the outbreak at the metropole hotel [ ] . the metropole hotel exemplified the potential international spread of infectious diseases. the index cases in the hong kong, toronto, singapore and hanoi outbreaks were all associated with the hotel. sars patients in ireland and united states had also visited the metropole hotel around the same time when there were other sick guests present in the hotel [ ] [ ] [ ] ] . subsequently there were hospital outbreaks when these index cases returned and were treated at their home countries. table showed the timeline of the sars action of the department of health. little was known about the new disease sars when the outbreak began at hotel and hospitals in february and early march. the who did not issue its first emergency travel advisory naming the illness as sars until march [ ] . there was local media coverage of an outbreak of atypical pneumonia in guangzhou on february , and the health authority in hong kong had made contact with the guangzhou and guangdong authorities. however, accurate information about the atypical pneumonia outbreak in guangdong province was not available to hong kong or the international community at the time. case investigation and contact tracing conducted by the department of health on february on the index case revealed that the guangzhou professor and his wife had stayed at the metropole hotel. however, no contact tracing was conducted in the hotel at that stage since the department of health had not received any other reports of severe community-acquired pneumonia related to the hotel [ ] . there were no environmental factors or triggers identified that warranted further action. however, environmental sampling on the carpet outside the room in which the index case resided, and elevator area showed a hot zone which tested positive for the sars virus by polymerase chain reaction (pcr) months after the index case stayed at the hotel [ ] . another study investigating german guests staying at the hotel also suggested the possibility of environmental contamination as a source of infection [ ] . it is not known how long the infectious virus persists in the surroundings of a sars patient. the established practice was for contact tracing note: materials extracted from references [ , ] to be conducted on close contacts (friends or family), but not on the basis of a shared location [ ] . a number of researchers estimated the basic reproduction number of sars by fitting models to the initial growth of the epidemics in a number of countries [ ] . modelling of sars epidemiology in hong kong and china showed rapid public health measures such as contact tracing for confirmed and suspected cases, and quarantining, monitoring, and restricting the travel of contacts had an effective reduction in reproduction number [ ] [ ] [ ] [ ] . a -year-old male from mexico arrived in hong kong on april , and stayed at the metropark hotel. he attended hospital on the same evening where he was admitted to an isolation ward. he subsequently developed a fever and was confirmed to have swine flu on may [ ] . the hong kong special administrative region (hksar) government raised the response level to 'emergency' on the same day under the emergency preparedness plan for influenza pandemic. an 'emergency response level steering committee on human swine influenza (flu a h n ) pandemic' was also established on the st may to formulate the overall disease control strategy [ ] . under the prevention and control of disease ordinance, the director of health ordered that all guests and staff at the metropark hotel should be quarantined on the evening of may [ ] . the quarantine was led by the department of health in collaboration with other government departments. quarantined persons were provided with oseltamivir (tamiflu) and other medical treatment. the social welfare department provided daily necessities and emotional support to the quarantined. a help desk was set up at the hotel involving the department of health, the home affairs department, the social welfare department, the immigration department, the civil aid service, the auxiliary medical service and the police. the quarantine ended week later, which covered the incubation period of influenza of to days. for those persons who had completed the quarantine period without showing symptoms of being infected, they were issued with certificates of conclusion of quarantine. at the same time, the centre for health protection (chp), other government departments and relevant agencies conducted contact tracing starting on the st may . close and selected social contacts were prescribed chemoprophylaxis and put under medical surveillance. the hotel and nearby streets, as well as other public places, were cleansed and disinfected. hygiene guidelines had been issued to all licensed hotels/ guesthouses and rented rooms to encourage enhanced cleansing and improvement of hygiene. all industrial associations had been informed of the situation and reminded the need to take precautionary measures. the occupational safety and health council had organised public seminars to raise public awareness of preparedness for influenza in the workplace [ ] . table showed the timeline of the swine flu action of the department of health. both the metropole hotel at kowloon (now renamed metropark hotel kowloon) and the metropark hotel at wan chai (now renamed kew green hotel) were four stars hotels situated at busy part of the city. both hotels were managed by the same management groupthe china travel service (holdings) hong kong limited. the two hotels were no different in terms of access to public health facilities and general standard of care. the difference in the timing of public health actions by the health authority was likely contributed by experience of sars preceding swine flu. after the sars outbreak in hong kong the health authority established the guidelines for hotels in preventing severe acute respiratory syndrome (sars) [ ] hygiene guidelines have been issued to all owners' corporations, owners' committee, mutual assistance committees and the hong kong association of property management companies, licensed hotels/guesthouses and bed space apartments to encourage enhanced cleansing and improvement of hygiene. note: materials taken from references [ , ] and guidelines on infection control & prevention in the hotel industry [ ] . the guidelines provided practical information for hotel staff members on how measures to prevent communicable diseases should be done. it offered comprehensive information on ways to implement infection control measures, in particular the maintenance of good hygiene on hotel premises [ ] . the chp organised infection control seminars for the hotel industry on a regular basis. for instance, in response to the ebola virus outbreak in west africa in - , the chp provided advice for the local hotel industry on receiving guests with a travel history or residence in an ebola virus disease affected area. the guideline stressed the importance of enquiring about the travel history of guests and outlined procedures on handling these guests who may feel unwell. the guideline reiterated the need to keep a record of staff and residents who had stayed in the hotel, with their personal and contact details, for possible future public health actions and contact tracing [ ] . ideally, hotels should be setting their own standards of hygiene measures and providing training to staff before an outbreak occurs. further roles and responsibilities included contingency arrangement, plan of acquisition of protective equipment, disease reporting and surveillance mechanism during outbreak period [ ] . from our online and database internet search, however, there is little mention of collaboration between the government and the hotel industry. no documentation was found on setting up of task forces or committees, or of invitation to hotel representatives to the working group advising on infection control guidelines in hong kong. sars served as the classic example of how tourism and international travel can present challenges to the global health system. the spread of the illness within a single hotel and the subsequent international air travel of the victims contributed to and accelerated the speed of the spread of sars across the globe. the experience from sars in hong kong had a profound impact on the public health reform especially on the infectious disease surveillance and epidemic response [ ] . these included strengthening the surveillance and the isolation and treatment of individuals with the disease according to case definitions, the establishment of communication channels between hotel and the government system, and the development of guidelines and response plans that allows the implementation of stringent infection control measures when necessary. the establishment of contingency plans and command structures including the 'emergency response level steering committee on influenza pandemic' allowed a clear structural framework and key lines of responsibility [ ] . however, collaboration with the private sector and the hotel industry were found to be limited and focused around infection control measures. according to subsequently published literature, application of appropriate measures had likely reduced the number of people who were infected, requiring medical care and died during the influenza pandemic [ ] . it has been shown that case isolation or household quarantine could have a significant impact at reducing attack rates in the community, and chemoprophylaxis can greatly reduce disease transmission during the pandemic [ , ] . however, the quarantine of guests at the metropark hotel in inevitably stirs up much discussion and controversy among the media and the public health community on the balance between the need to protect the public health and the need to safeguard civil liberties. the decision of quarantine created enormous tension between the government, guests and the hotel management. the decision of the need for quarantine and the scale of the quarantine needs to be scientifically justified. the negative effects overall of such a policy on the tourism attractiveness of a destination cannot be neglected. the quarantine at the metropark hotel during swine flu also highlighted the extensive assistance needed for the quarantined persons, and the cooperation necessary in the possible future need for a hotel quarantine. pre-established partnerships and coordination between the government and the hotel industry is key in epidemic preparedness and response. studies have shown that the psychological impacts of sars and the government restrictions on travel, had a great impact on the travel industry far beyond the region of sars hit areas [ ] . for the hotel industry in hong kong, the number of hotel guests dropped dramatically to a level that was never experienced before [ ] . in order for hotels to sustain their business, the hong kong hotel industry adopted an industry-wide recovery effort and empathized on mutual support [ ] . previous papers called for a better preparedness of the hotel industry for future crises and epidemics [ , ] . collaborations with the hotel industry to mitigate the impact of epidemics hotels are often the first point of contact for tourists arriving at a host country. hotels could provide an additional line of defence beyond entry border screening, and they could offer another layer of protection against illnesses that border screening processes may have missed, for example in the situation where travel occurs during the incubation period of an infectious disease. in view of this, the capacity of hotels in the detection of potential illness and the launching of an initial response should be fully recognised and utilised. the who pandemic influenza risk management recommended involving civil society and the private business sector in pandemic preparedness planning and national committees [ ] . the case of hotel industry collaboration with the health sector in hong kong has the potential to provide a positive example of effective disaster risk reduction coordination. the epidemic preparedness and infection control measures mounted against sars and h n swine flu demonstrated a role that needed to be filled by the hotel industry. during sars, late recognition of the environmental contamination of hotel facilities and the failure of timely intervention on the hotel guests with close contact contributed to the spread of the disease internationally. while the appropriateness and best method of quarantine in future pandemic influenza warrants further research, the swine flu hotel quarantine exposed gaps in the partnership with hotel industry. health authorities in hong kong had since provided guidelines mostly in the area of disinfection and hygiene, and focused on educating hotel workers on basic hygiene to prevent the spread of infectious diseases. the potential to establish traveller screening, timely reporting and isolation for the infected guests during epidemics could be explored. the capacity of the hotel industry in controlling infections should be recognised not only in hong kong but also in other parts of the world. the world bank. international tourism, number of arrivals world health organization. international health regulations european centre for disease prevention and control. facts about severe acute respiratory syndrome (sars) sars: clinical presentation, transmission, pathogenesis and treatment options world health organisation. summary of probable sars cases with onset of illness from learning from sars: preparing for the next disease outbreak: workshop summary european centre for disease prevention and control. factsheet on swine influenza in humans estimated global mortality associated with the first months of pandemic influenza a h n virus circulation: a modelling study prevention and control of human swine influenza infection in hong kong severe acute respiratory syndrome (sars): a year in review epidemiology of severe acute respiratory syndrome (sars): adults and children progress in global surveillance and response capacity years after severe acute respiratory syndrome sars: retrospective cohort study among german guests of the hotel 'm sars expert committee. sars in hong kong: from experience to action available at the sars epidemic in hong kong: what lessons have we learned? update: outbreak of severe acute respiratory syndrome -worldwide world health organization. consensus document on the epidemiology of severe acute respiratory syndrome (sars) epidemiological determinants of spread of causal agent of severe acute respiratory syndrome in hong kong the impact of public health control measures during the sars epidemic in mainland china epidemiology, transmission dynamics and control of sars: the - epidemic impact of quarantine on the sars outbreak: a retrospective modeling study administrative region (hksar) government. preventing severe acute respiratory syndrome (sars) guidelines for hotels guidelines on infection control and prevention in hotel industry. centre for health protection centre for health protection. health advice for hotel industry on serving guests with history of travel to or resided in the ebola virus disease (evd) affected areas the impact of the severe acute respiratory syndrome on hotels: a case study of hong kong preparedness plan for influenza pandemic the government of the hong kong special administrative region european centre for disease prevention and control. guide to public health measures to reduce the impact of influenza pandemics in europe strategies for mitigating an influenza pandemic public health interventions and sars spread the severe acute respiratory syndrome: impact on travel and tourism the survival of hotels during disaster: a case study of hong kong in pandemic influenza risk management: who interim guidance. geneva: world health organization chronology of major events of the sars incident in hong kong available at legislative council panel on health services not applicable. no funding available for this study.availability of data and materials not applicable. ethics approval and consent to participate not applicable. not applicable. the authors declare that they have no competing interests. springer nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. key: cord- - c x hx authors: zhao, sheng zhi; wong, janet yuen ha; wu, yongda; choi, edmond pui hang; wang, man ping; lam, tai hing title: social distancing compliance under covid- pandemic and mental health impacts: a population-based study date: - - journal: int j environ res public health doi: . /ijerph sha: doc_id: cord_uid: c x hx the success of public health measures for controlling the coronavirus disease (covid- ) pandemic relies on population compliance. we analyzed compliance with social distancing and its associations with mental health. the hong kong covid- health information survey was conducted from – april on adults randomly sampled for landline telephone interviews (n = ) and online surveys (n = ). compliance with social distancing and staying-at-home, stress (perceived stress scale- ), anxiety (general anxiety disorders- ), and depressive symptoms (patient health questionnaire- ) were collected. the associations between mental health symptoms and compliance were examined by multivariable regression models. of the respondents ( . % female, . % aged – years), . %, . %, and . % reported avoiding going out, going to crowded places, and attending social gatherings of more than four people, respectively. most respondents had stayed-at-home for at least four of the past seven days ( . %; mean . , standard deviation . ). adoption, perceived effectiveness, and perceived compliance with social distancing were associated with lower stress levels and less anxiety and depressive symptoms (all p < . ). however, more days stayed-at-home were associated with more depressive symptoms (adjusted odds ratio . ; %confidence interval . , . ). the long-term psychological impact in relation to social distancing and staying-at-home requires further investigation. the coronavirus pandemic (covid- ) has caused millions of confirmed cases and thousands of deaths since early . driven by the increasingly frequent worldwide transportation of those with asymptomatic patients, the infection is spreading more rapidly and widely than ever [ ] . public health measures such as border restrictions, bans on public gatherings, closures of schools and nonessential businesses, stay-at-home and social distancing have been enforced in many countries. at the early stage of the epidemic, hong kong responded quickly with precautionary behaviors including mask wearing and hand hygiene [ ] [ ] [ ] . solidarity and altruism were aroused for collective community protection [ ] . isolation, quarantine, contact tracing and social distancing were the main measures to prevent community outbreak and were effective in that the transmission of covid- remained low (daily effective reproduction number r approximately equal to ) by early march without lock the hong kong covid- health information survey (covhins) was a population-based dual sampling landline and online survey conducted from - april . the target population was general hong kong residents aged or above. social policy research limited, a reputable local survey agency, was commissioned to conduct the survey. we adopted two-stage random sampling in the landline survey using the web-based computer-assisted telephone interview system (web-cati). residential telephone directories that covered approximately % of hong kong residents [ , ] were used to generate a random list of telephone numbers for interview. invalid numbers (e.g., fax line, non-residence line and non-working line), nonresponses, and ineligible households were excluded. after telephone contact had been successfully established with a target household, one eligible person was selected using the "next birthday" rule (i.e., the household member whose birthday was nearest to the interview date was selected). all telephone interviewers completed a half-day training related to covid- knowledge, contents of the questionnaire, sampling procedures and interviewing techniques. briefing and de-briefing sessions were arranged during data collection, and rigorous quality checks were adopted ( . % were checked) to ensure research fidelity. each interview took approximately min. among the valid telephone number sampled ( refused, dropout), respondents completed the interview yielding a response rate of . %. the online survey was conducted on a representative panel of hong kong residents. this panel was previously formed by inviting local mobile phone users to join. all mobile phone numbers (prefix starting with , or ), which covered over % of hong kong residents, received an invitation message. these numbers were generated using the numbering plan for telecommunication services in hong kong provided by the office of the communications authority (ofca). a total of , residents covering diverse socio-economic backgrounds joined the panel. stratified random sampling by sex and age was adopted to select a random list of panel participants, who were then invited to join the online survey by an invitation text message. participants self-administered the questionnaire via web-cati. the response rate was . % ( of eligible panel participants). ethics approval was granted by the institutional review board (irb) of the university of hong kong/hospital authority hong kong west cluster (uw - ). informed consent was obtained from all respondents before answering the questions. the adoption of social distancing measures (yes/no) since the first case confirmed in hong kong included: (i) avoid going out, (ii) avoid going to crowded places, (iii) avoid going to high-risk places (e.g., bar, wet market, hospital), (iv) avoid social gatherings of more than four people (government regulation, with penalty, issued on th march), (v) avoid greetings with physical contact such as handshaking, hugging and kissing, and (vi) keep . meters from others in public. the total number of social distancing measures was calculated (ranged - ). perceived overall effectiveness of and perceived compliance with the above social distancing measures were measured on a scale ranging from - with higher scores indicating higher perceived effectiveness and compliance. stay-at-home, which was voluntary, was measured by the number of days at home except for essential tasks in the past seven days. personal protection measures including: (i) wearing surgical mask, (ii) washing hands with alcohol-based sanitizers, (iii) using alcohol to clean daily necessities, and (iv) adding water to household drainage system in the past seven days were recorded. stress level in the preceding month (from early-march to mid-april ) was assessed by the four-item perceived stress scale (pss- ) [ ] . pss- consists of four items measuring the degree of ability to cope with existing stressors (positive elements, two items, cronbach's α = . ) and the degree of lack of control and affective reactions (negative elements, two items, cronbach's α = . ). each item is rated on a likert-like scale ranged from (never) to (very often). higher total scores on the four items ( - ) indicate a higher perceived stress level. the chinese version of pss- has been validated in our previous study with satisfactory internal consistency (cronbach's α = . ) [ ] . anxiety and depressive symptoms in the past two weeks (from late-march to mid-april ) were assessed using the four-item patient health questionnaire (phq- ). phq- consists of the two-item general anxiety disorder (gad- ) and the two-item patient health questionnaire (phq- ) [ , ] . gad- covered two core criteria for generalized anxiety that screen for social panic and anxiety disorders. phq- measured depressive symptoms, depressed mood and loss of interest, two core diagnostic criteria for major depression disorder [ ] . each item scores on a likert-like scale ranging from (not at all) to (nearly every day). subscales of the gad- and phq- scores range from - with a score of ≥ indicating anxiety and depression symptoms [ , ] . we have previously validated the chinese version of the phq- in the hong kong population [ ] . the internal consistency of gad- (cronbach's α = . ) and phq- (cronbach's α = . ) were positive in this study. sex, age, marital status (never married, married or cohabited, divorced or separated, or widowed), current living arrangement (living alone, co-living with family members, or co-living with other people), and socioeconomic status (ses) including educational attainment (primary or below, secondary, or tertiary), employment status (full-time work, part-time work, student, housemaker, unemployed or retired) and monthly personal income (hk$ ≤ , ; , - , ; , - , , , - , , or ≥ , ; us$ = hk$ . ) of the respondents were recorded. we used chi-squared test and t-test to compare sociodemographic characteristics and mental health symptoms between the landline telephone and online self-administrated samples. to improve the representativeness of the sample, all data were weighted according to provisional figures obtained from the census and statistics department on the sex, age, and education attainment distributions of hong kong's general adult population in . multivariable linear regression was used to examine the associations with sociodemographic characteristics of number of social distancing measures adopted, number of days stayed-at-home and perceived compliance with social distancing measures. the association of mental health symptoms including stress, anxiety and depression with the number of measures adopted, number of days stayed-at-home and perceived effectiveness and compliance were calculated by multivariable linear (for stress) and logistic (for anxiety and depression) regressions. in regression model , potential sociodemographic confounders including sex, age, educational attainment, current employment status, and monthly income were adjusted. we additionally adjusted for the four personal protection measures in regression model . the association between personal protection measures and mental health symptoms were analyzed by multivariable regression models adjusted for sociodemographic factors and social distancing. effect modifications by age ( - , + years) and education attainment (primary or below, secondary, and tertiary) on the associations between mental health symptoms, stay-at-home and compliance with social distancing were assessed using the interaction terms. analyses were performed using stata version/mp . (statacorp lp, college station, tx, usa). there were no significant differences in the sociodemographic characteristics of the landline telephone sample (n = ) and the online self-administrated sample (n = ) (all p > . ; table ). in the combined weighted sample, . % were female, . % aged - years, . % were married or cohabitated, and . % were co-living with family members. three quarter ( . %) of respondents had a secondary or higher education, . % were employed and . % had a monthly household income of hk$ , or lower. the average stress score was . (standard deviation, sd: . ), and . % and . % of the respondents had experienced anxiety and depressive symptoms, respectively. table shows that most respondents adopted the social distancing measures including avoid going out ( . %), avoid going to crowded places ( . %), avoid social gatherings of more than four people ( . %), avoid going to high-risk places ( . %), and avoid handshaking, hugging and kissing ( . %), but only . % kept . meters away from others. respondents adopted on average . (sd . ) social distancing measures and most had stayed-at-home for at least four days in the past seven ( . %; mean . , sd . ). respondents perceived the social distancing measures to be effective in containing the infection (mean . , sd . ) and perceived a moderate level of compliance (mean . , sd . ). table shows that older age and higher education attainment were significantly associated with the adoption of more social distancing measures, more days stayed-at-home and perceived higher level of compliance with social distancing (all p for trend < . ). being female was associated with more days stayed-at-home (adjusted β . ; %ci . , . ) and perceived compliance with social distancing (adjusted β . ; %ci . , . ). compared with respondents in full-time work, those who were economically inactive spent more days at home and reported higher compliance with social distancing (all p for trend < . ). having higher income was associated with increased perceived compliance with social distancing (p for trend < . ). table shows that adopting more social distancing measures was significantly associated with lower stress level (adjusted β − . ; %ci − . , − . ) and lower risk for anxiety symptoms (adjusted or . ; %ci . , . ) after the models were adjusted for sociodemographic and personal protection measures (model ). perceived effectiveness and compliance with social distancing measures were associated with lower stress levels and risks for anxiety and depressive symptoms (all p < . ). consistently, personal protection measures, including mask wearing, use of alcohol to clean daily necessities and adding water to the household drainage system were associated with lower stress levels and lower risks for anxiety and depressive symptoms (all p < . ) (supplementary table s ). nevertheless, more days stayed-at-home was significantly associated with increased risk for depressive symptoms (adjusted odd ratio (or) . ; %ci . , . ). supplementary table s shows that more days stayed-at-home was associated with anxiety (p for interaction = . ) and depressive (p for interaction = . ) symptoms especially among respondents with older age ( + years). more days stayed-at-home was associated with a higher stress level especially among respondents with primary or lower education attainment (p for interaction = . ). we have provided the first evidence on compliance with non-pharmaceutical community containment strategies including stay-at-home and social distancing and their associations with mental health symptoms during the covid- pandemic. random samples from landline and mobile phone increased the representativeness of the study. the effectiveness of public health interventions depends on the degree of population engagement and compliance in practice. avoiding going out and avoiding social gatherings were mostly practiced, which may have resulted in the achievement of suppressing the first wave of community outbreak in february and march (first eight weeks) and in mitigating the second wave, due to imported cases, in april and may [ ] . most respondents have voluntarily stayed at home for at least four days in a week except for essential tasks (e.g., shopping for daily necessaries). perceived overall compliance was satisfactory considering no lockdown has been implemented and some must maintain a normal working life. keeping a physical distance of . meters, especially in public transportation, workspaces and restaurants, is demanding in crowded metropolitan districts such as hong kong. flexible working schedules to avoid crowded transportation, home office working, and closure of unessential businesses may supplement these distancing measures [ ] . being female, older age, and having higher ses were associated with higher levels of perceived compliance with social distancing measures. without the need for work-related essential tasks, the practice of stay-at-home and social distancing is easier for economically inactive people (e.g., students with class suspensions, homemakers, or retirees). the early reported higher mortality rate among older adults (aged +) [ ] might have raised alarm, leading to higher compliance with home-confinement in the elderly. females and people with higher ses were more vigilant in recognizing and practicing public health measures. one possible explanation is that women and people with a higher ses are more health conscious [ ] . in contrast, males with lower ses may have more essential job requirements and less flexible working schedules, which may lead to lower compliance. knowledge of infectious disease, social norms and perceived effectiveness of the measurements were reported to be decisive regarding level of compliance [ ] . timely epidemiological reports, combined with minute-by-minute case reports and open contact tracing, may have strengthened health communication and population-wide adoption of precautionary measures during this pandemic [ , ] . the perceived effectiveness of and compliance with social distancing were associated with lower risks of mental distress. consistently, personal protection measures including mask wearing and household disinfection were associated with less stress and depressive symptoms, adjusted for social distancing. the association between social distancing and mental health remained robust after additional adjustment for personal protective measures. perceived effectiveness and compliance with public health measures in preventing the infection for oneself and family members, and contributing to the safety and health of the community and country may strengthen feelings of security and alleviate mental distress related to the pandemic. a repeated cross-sectional study conducted in january, february and march has reported that perceived susceptibility to worries about being infected was decreasing, while confidence in protecting oneself was increasing in hong kong [ , ] . personal protective measures such as mask wearing have become a social norm, and this perceived protection and solidarity may further enhance individual compliance [ ] . dynamic fluctuation in mental well-being is possible following different stages of the pandemic and the effectiveness of control measures. areas experiencing severe outbreaks and with poor community control may encounter shortages in preventive supplies, more worries about being infected, less confidence in self-protection, less compliance with social directives and more serious mental health crises. in contrast, staying at home for a longer time was associated with increased risks of depressive symptoms. reverse causation is possible in which respondents with depressive symptoms might have tended to stayed-at-home. however, a crowded living environment, restricted face-to-face social interactions and restricted outside activities have led to a physically inactive and sedentary lifestyle for months, which may contribute to boredom, low mood, or mental distress. the elderly and less educated population might be more vulnerable regarding the processing of health information and sudden changes in social rules, especially in the digital world where public communication is mostly performed online [ , ] . we found in our subgroup analysis that older and less educated adults were more vulnerable to mental health symptoms if they stayed for more days at home. increasing knowledge and promoting the use of preventive measures for the most vulnerable individuals is urgently needed in order to increase compliance with social distancing and maintain mental well-being. health care providers have an important role in addressing mental distress as part of the pandemic response, improving compliance with social distancing and helping reduce the impact of covid- on mental health. decline in virus transmission and ease of public health restrictions are yet to come in this worsening pandemic. social distancing is in need of collective effort for a long period of time in most affected countries and areas [ ] . the long-term psychological impact in relation to the pandemic and social distancing measures requires further nation-and world-wide investigation. some limitations of the study should be noted. causal relations could not be inferred in this cross-sectional study, where respondents with psychological distress were less likely to comply with public health measures. pre-existing psychological problems were not collected, and residual confounders were not able to be excluded. recall bias may exist in self-reporting measurements. the reasons for non-compliance with social distancing need further investigation for further public directives to be put into practice. the pss- has a satisfactory construct validity [ ] but a somewhat lower reliability (cronbach's α < . ). however, the reliability coefficient of . should not seriously attenuate validity [ ] and the scale was consistent with pss- and pss- in correlations with other health-related variables, which provides a concurrent validity of the scale [ ] . simple measurements of mental health symptoms have restricted the clinical implications and more rigorous measurements are warranted. however, diagnostic instruments could be hard to implement in such a population-based survey. respondents identified with higher stress level and having anxiety or depressive symptoms could benefit from further psychological assessment and support. we measured immediate mental health symptoms during the epidemic, and long term psychosocial responses such as social inactivity, post-traumatic stress disorder, and subthreshold or clinical anxiety and depression disorder will need further investigation. compliance with social distancing and stay-at-home is higher among female, older and educated respondents. compliance with and perceived effectiveness of social distancing were associated with lower levels of stress, anxiety and depressive symptoms. more days stayed-at-home, however, may increase the risk of depressive symptoms, especially in older adults. public health interventions are needed to protect the "new normal" in a future with or without covid- . the long-term psychological impact in relation to social distancing and stay-at-home requires further investigation. social support and targeted interventions for the psychological well-being of the most underprivileged community members are urgently needed. presumed asymptomatic carrier transmission of covid- impact assessment of non-pharmaceutical interventions against coronavirus disease and influenza in hong kong: an observational study community responses during early phase of covid- epidemic mass masking in the covid- epidemic: people need guidance wearing face masks in the community during the covid- pandemic: altruism and solidarity the incubation period of coronavirus disease (covid- ) from publicly reported confirmed cases: estimation and application temporal dynamics in viral shedding and transmissibility of covid- depression and anxiety in hong kong during covid- multidisciplinary research priorities for the covid- pandemic: a call for action for mental health science the psychology of pandemics: preparing for the next global outbreak of infectious disease the psychological impact of quarantine and how to reduce it: rapid review of the evidence an overview of systematic reviews on the public health consequences of social isolation and loneliness -ncov epidemic: address mental health care to empower society public mental health crisis during covid- pandemic factors influencing compliance with quarantine in toronto during the sars outbreak the covid- pandemic calls for spatial distancing and social closeness: not for social distancing! public health interventions for covid- : emerging evidence and implications for an evolving public health crisis scientific and ethical basis for social-distancing interventions against covid- from a sprint to a marathon in hong kong effective containment explains subexponential growth in recent confirmed covid- cases in china using information and communication technologies for family communication and its association with family well-being in hong kong: family project the association of problematic smartphone use with family well-being mediated by family communication in chinese adults: a population-based study a global measure of perceived stress three versions of perceived stress scale: validation in a sample of chinese cardiac patients who smoke an ultra-brief screening scale for anxiety and depression: the phq- a -item measure of depression and anxiety: validation and standardization of the patient health questionnaire- (phq- ) in the general population screening for anxiety disorders with the gad- and gad- : a systematic review and diagnostic metaanalysis detecting and monitoring depression with a two-item questionnaire (phq- ) screening for depression with the patient health questionnaire- (phq- ) among the general population in hong kong clinical course and risk factors for mortality of adult inpatients with covid- in wuhan, china: a retrospective cohort study the gender gap in mortality: how much is explained by behavior? j. health econ how to improve adherence with quarantine: rapid review of the evidence health information exposure from information and communication technologies and its associations with health behaviors: population-based survey protecting older adults during social distancing uses and abuses of coefficient alpha we thank the respondents for their participation in the survey. the authors declare no conflict of interest. key: cord- -dq xu c authors: poutanen, susan m.; mcgeer, allison j. title: transmission and control of sars date: journal: curr infect dis rep doi: . /s - - - sha: doc_id: cord_uid: dq xu c severe acute respiratory syndrome (sars) was first recognized in china in november and was subsequently associated with a worldwide outbreak involving people, of whom died. the outbreak was declared contained on july , , after the last human chain of transmission of sars had been broken. whether outbreaks of sars will return is debatable, but no one disagrees that it is important to be prepared for this possibility. this article presents an overview of the transmission and control of sars based on the current state of knowledge derived from published studies of the outbreak and on our own personal experience. severe acute respiratory syndrome (sars) was recognized in march as a global threat after first appearing in china in november [ ] . an outbreak followed, spanning countries and involving people, of whom died [ ] . health care workers represented % of cases overall and up to % in some countries. on july , the world health organization declared the outbreak contained [ ] . since then, in september and december , two isolated cases have been reported in researchers in singapore and taiwan working in laboratories culturing sars-associated coronavirus (cov), the newly discovered coronavirus identified as the cause of sars [ , ] . in addition, four isolated cases with relatively mild symptoms and no evidence of secondary transmission have been identified in individuals in china in december and january [ , ] . increasing evidence suggests that sars-cov originated from interspecies transmission of a sars-cov-related virus from animals to humans, with the himalayan palm civet being one of the most likely animals involved [ ••, •, ] . genotypic analysis of sars-cov strains from the recent outbreak reveals that genotypes from persons affected early in the outbreak are more similar to animal sars-cov-related viruses than genotypes from persons affected in the middle and later parts of the outbreak. the genotype changes are consistent with positive selective pressures resulting eventually in stabilization and emergence of a predominant genotype [ ••] . genotypic analysis of the virus involved in one of the recent isolated cases of sars identified in china reveals that it is much more closely related to the sars-cov-related virus of palm civets than any human sars-cov detected in the previous outbreak [ ••] . this finding, with seroprevalence data revealing that a small proportion ( . %) of healthy persons in hong kong had been exposed to sars-cov-related viruses at least years before the recent sars outbreak [ •] , suggests that occasional human infection with animal sars-cov-related viruses may have occurred undetected for years before the outbreak and may continue to occur. unlike the outbreak sars-cov virus, animal sars-cov-related viruses may not have the same propensity to cause severe human disease and may not be able to be transmitted from human to human. further investigation is needed to understand the circumstances that permitted the selective adaptation and purification processes that resulted in the evolution of the sars-cov outbreak strains. whether sars outbreaks will return is debatable [ ] [ ] [ ] . the most likely source of individual human cases is research laboratories that work with live sars-cov. however, appropriate biosafety measures should minimize this risk, and awareness of this risk should permit early detection of cases and implementation of control measures so that transmission, if it occurs, should be limited. the most likely source of outbreaks is the replication of the event(s) that resulted in the evolution of the sars-cov outbreak virus from animal sars-cov-related virus. the existence of human or animal reservoirs of the outbreak sars-cov virus has been postulated, but is extremely unlikely [ ] . although it is unclear whether new outbreaks of sars will occur, it is important to be prepared for the possibility that they will. indeed, much research is ongoing, optimizing diagnostic tests, treatments, and vaccination directed at sars, and vigilant surveillance is being completed worldwide. part of this preparation includes understanding the timing and modes of transmission of sars, and the strategies that allowed for the effective control of the outbreak. during the outbreak, it was evident that sars was readily transmissible from person to person, especially in health severe acute respiratory syndrome (sars) was first recognized in china in november and was subsequently associated with a worldwide outbreak involving people, of whom died. the outbreak was declared contained on july , , after the last human chain of transmission of sars had been broken. whether outbreaks of sars will return is debatable, but no one disagrees that it is important to be prepared for this possibility. this article presents an overview of the transmission and control of sars based on the current state of knowledge derived from published studies of the outbreak and on our own personal experience. care facilities. however, how transmissible, for what period, and by which modes was unclear. since the outbreak, much effort has been placed on better understanding these issues. the incubation period of sars is to days, with a mean of to days [ •] . outliers include a small proportion (< %) of cases with incubation period as short as day and as long as days [ •] . there is no evidence of communicability before symptom onset, and transmission is infrequent during the first few days of illness. risk for transmission appears to be greatest in patients who are most severely ill and peaks during the second week of illness, corresponding with the timing of peak viral load [ •, ] . most countries considered sars patients to be potentially infectious until days after resolution of fever and signs of clinical improvement, and isolation precautions were not discontinued until this occurred. there is no evidence of transmission from anyone treated in this manner, and it is possible that isolation for a shorter time period would be sufficient. despite the absence of transmission, sars-cov viral rna remained detectable in respiratory secretions and stool and urine specimens for more than days in some patients [ ] . this may be explained by the fact that viral rna does not necessarily correlate with the presence of viable virus; indeed, positive viral cultures were noted predominantly in the first weeks of illness, with no positive cultures after the third week of illness [ ] . there is no evidence of relapse of sars-cov infections. sars-cov has been detected in respiratory specimens, stool, and to a lesser extent, in blood, urine, and conjunctival secretions [ ] . respiratory droplet and direct contact are the primary modes of sars transmission. evidence for this includes studies in hong kong and toronto, canada that show an increased risk for sars in health care workers who entered the room of a patient with sars, with increasing risk in those with closer proximity to the patient and those remaining in the room for a longer duration, suggesting that transmission is enhanced by close, prolonged contact [ •, •] in addition, an increased risk in household members of patients with sars has been shown in those who had close, prolonged contact with the index person, and in particular, in those who shared a bed, reported being within meter of the index person, and dined together [ •] . increasing risk was noted as the duration of time the symptomatic index patient spent at home increased. exposure to respiratory secretions appears to pose a particular risk, with higher risks for sars noted in health care workers who assisted with intubation, suctioned before intubation, manipulated oxygen masks, or were present during noninvasive ventilation of a sars patient for more than minutes [ •, •] , in addition to higher risks being noted in household members of sars patients who were coughed at by the index person within meter [ •] . a summary of the results of these studies is outlined in table . whether exposure to fecal material poses a particular risk has not been as well-documented. however, given the high proportion of stool samples positive for sars-cov by molecular tests (up to % in some studies), one can propose that transmission through stool is likely [ •] . although no study has documented the role of fecal-oral transmission, fecal droplet transmission was thought to have played a significant role in the amoy gardens community outbreak in hong kong. fecal droplets were thought to have resulted from unsealed floor drain traps that permitted an open connection to the soil stack. widespread transmission of these droplets was thought to have resulted from the temporary shutdown of the flush water system, powerful room exhaust fans, and a building layout permitting exhausted droplets to re-enter the building at other locations [ ] . the extent to which fomites play a role in the transmission of sars through indirect contact also is unclear. although there is no evidence to suggest that fomites played a significant role in the recent outbreak, the fact that sars-cov is able to survive up to days at room temperature on several inanimate surfaces suggests that this mode of transmission is possible [ ] . evidence to support this includes a study in hong kong in which self-reported inconsistent hand hygiene practices were associated with an increased risk for sars among health care workers who reported no contact with patients (odds ratio = . [ . - . ]; p = . ) [ • ]. in addition, in the amoy gardens outbreak, lack of household disinfection was associated with an increased risk in household members of patients with sars [ • ]. in addition to droplet and contact transmission, limited evidence suggests that airborne transmission may occur on occasion. the studies that suggested this possibility describe specific sars clusters in which the pattern of transmission for a subset of individuals cannot be explained by droplet or contact transmission. for example, in a study assessing medical students exposed to a single patient, four students who were not within the -feet droplet risk zone [ ] from the patient acquired sars [ •] . in an investigation of a nosocomial outbreak in toronto, one health care worker who had not worked in the index patient's room acquired sars [ •]. on a flight carrying a symptomatic person with sars, % of the persons who became ill were seated more then feet away from the index patient [ ] . although all of these examples are consistent with possible airborne transmission, alternate explanations implicating indirect contact transmission or unrecognized exposures also are possible. in addition, one can postulate that an enhanced droplet transmission mechanism exists in which droplets are capable of being transmitted beyond the traditional -feet radius from the index patient but are incapable of traditional airborne transmission. particularly worrisome during the outbreak were reported scenarios in which transmission occurred despite the use of droplet, contact, and airborne precautions. for example, a nurse who was wearing an n respirator, two sets of gowns and gloves, safety glasses, a face shield, hair cover, and shoe covers acquired sars after providing bagvalve-mask ventilation to a patient with sars [ ] . in addition, at least two health care workers using n equivalent respirators, gown, gloves, and safety glasses, with or without a face shield, acquired sars after assisting in the provision of noninvasive ventilation and a difficult intubation of a patient with sars complicated by copious frothy secretions [ ] . common factors in these scenarios include being involved in a procedure that has the potential to generate aerosols (eg, noninvasive ventilation, intubation) that is being performed on severely ill patients and requires close contact with the patient in the context of using n or n equivalent respirators that were not fittested. potential explanations for the through-precautions transmission seen in these scenarios include the possibility of unrecognized breaches in precautions, contamination upon removal of precautions, or an airborne viral load high enough to overwhelm the non-fit-tested n or n equivalent respirators used. whether n respirators require fit-testing in order to be effective in reducing airborne transmission has not been studied in the clinical setting. although the united states has supported fit-testing for all n respirators since , other countries such as canada have only done so in response to sars and specifically in response to the through-precautions transmission scenarios described earlier [ ] . further study is needed to definitely determine the role of fit-testing in preventing air-borne transmission and to better understand the mechanisms responsible for through-precautions transmission. based on analyses of the outbreaks in hong kong and singapore, the basic reproduction number for sars, r o , defined as the expected number of secondary infectious cases generated by an average infectious case in an entirely susceptible population, is estimated between . and . [ , ] . this is consistent with an infectious disease spread by contact or droplet transmission [ •] . the relatively fast decrease in the effective reproduction number, r t , to less than noted after implementation of control measures, is suggestive of an infectious disease with relatively low efficiency in transmission that is readily controlled [ ] . data from recent seroprevalence studies support this showing that in typical situations relatively few people with exposure to patients with confirmed sars-cov infection actually became infected. for example, typical attack rates among health care workers in hospital settings who used no protection or inconsistent protection ranged from % to . % [ ] [ ] [ ] [ ] . typical attack rates in household settings ranged from . % to % [ •, ] . typical attack rates on flights were % to . % [ , ] , and no significant transmission was seen with casual contact in the community setting [ ] . however, notable exceptions to this typical transmissibility are so-called superspreading events, in which transmission of sars-cov was shown to be highly efficient, with attack rates as high as % on one flight [ ] and % [ ] and % [ •] in some hospital settings. for example, in guangzhou, the index patient was shown to transmit sars to other individuals, with an associated large cluster of secondary infections giving rise to the outbreak in guangzhou [ ] . in singapore, multiple superspreading events were described at the beginning of the outbreak, with one individual responsible for at least other cases of sars through direct contact [ ] . in canada, superspreading events also were described in the index hospital in toronto, with one patient directly responsible for other cases of sars and with attack rates among exposed staff as high as % [ ] . it has been proposed that the presence of a superspreading event was likely the dominant factor influencing which countries were significantly involved in the recent worldwide outbreak [ • ]. there is a limited understanding of what causes superspreading events, but it is generally believed that a combination of host, environment, and virus interactions is involved. host factors, such as age, underlying illness, and increased severity of sars symptoms may be associated with increased viral shedding, permitting more efficient transmission. shen et al. [ •] have shown that cases associated with superspreading in beijing were more likely to be older patients with high case fatality rates. increased opportunity for exposure through increased interaction with patients (such as that which typically occurs in hospitals settings) may further aid transmission. this is confirmed in the study by shen et al. [ •] , which showed that superspreading patients in beijing were more likely to have higher numbers of close contacts than were patients unassociated with superspreading. although association with aerosol-generating procedures was not seen in beijing, it has been proposed as an alternate explanation that may further facilitate transmission in superspreading events. inadequate infection control precautions also may be partly responsible, and after the implementation of control measures in beijing, superspreading events were greatly reduced [ •] . whether strain variations in sars-cov or coinfections with other organisms might play a role in these situations has not been fully assessed. superspreading events are not unique to sars but also have been described with other diseases such as ebola, rubella, and measles [ •, ] . additional investigation is needed to further understand the role of various determinants of superspreading events in sars. control of sars depends on the rapid identification of cases and early implementation of control measures such as isolating the patient, using appropriate personal protective equipment, contact tracing, and possibly implementing quarantine. community measures, such as travel restriction and airport screening, also were implemented in the recent outbreak and may play a role in the event of a larger outbreak. implicit in these measures is the need to educate health care workers in addition to the general public. a general paradigm shift regarding how one approaches potentially infectious persons is needed given the ongoing threat of emerging infectious diseases such as sars. in order to identify cases early in the course of a patient's illness, implementation of surveillance programs is needed at the hospital and community level. given the uncertainty as to whether sars will return and the costs associated with implementing surveillance programs, surveillance efforts ideally would not be restricted to sars but would be incorporated into general surveillance efforts for other potentially communicable infectious diseases, which are already in place in most institutions and community settings. surveillance for sars is complicated because clinical features alone cannot distinguish sars from other respiratory infections or from the many possible explanations for fever and pulmonary infiltrates in patients with multiple comorbidities. surveillance is further complicated because adequately sensitive rapid diagnostic tests are unavailable early in the disease [ ] . thus, surveillance for sars should rely on screening for patients who have compatible clinical features in the context of potential sars-cov exposure. epidemiologic risks to consider include: exposure to settings where sars activity is suspected or documented; a person with an epidemiologic link to a cluster of persons with unexplained respiratory illness, especially when such a cluster occurs within a single health care facility setting; a health care worker with direct patient-care responsibilities; or a laboratory worker in a laboratory that contains live sars-cov [ ••] . upon identification of possible cases of sars on the basis of these clinical and epidemiologic factors, appropriate infection control precautions should be initiated and laboratory testing for sars and alternative diagnoses that might explain the illness should be completed. infection control precautions should be continued until sars has been ruled out or alternative diagnoses have been identified that fully explain the patient's symptoms. updated infection control practice recommendations for use with patients with possible or confirmed sars are available [ ••] . as evidence accumulates regarding the effectiveness of infection control measures used in the recent outbreak, revisions of these recommendations are being made. a summary of some of the most informative studies regarding effectiveness of specific infection control precautions is presented here and outlined in table . seto et al. [ • ] completed a case-control study involving health care workers, of whom acquired sars, from five hong kong hospitals. they noted that the risk for acquiring sars after direct care of a patient with sars was significantly reduced with the use of n respirators or surgical masks and gowns, and hand-washing. multivariate analysis revealed masks (n respirators or surgical masks) to be the only significant protective measure. the authors contend the fact that surgical masks and n respirators were effective, with the finding that % of noninfected staff did not use masks of any type, supports that transmission is not typically airborne. loeb et al. [ • ] completed a retrospective cohort study among nurses, eight of whom acquired sars after working in one of two toronto critical care units with sars patients. they noted that the consistent use of n respirators was significantly more protective than was not wearing a mask. the consistent use of surgical masks also reduced the risk, but not significantly. n respirators appeared to reduce the risk more than did surgical masks, but not significantly. the use of gowns and gloves was not shown to significantly reduce the risk for sars. lau et al. [ • ] completed a case-control study involving heath care workers with sars and matched controls from hong kong. they noted that transmission of sars occurred despite almost all of the study respondents using n respirators or masks when providing direct care for patients with sars, suggesting that masks were not sufficient to prevent transmission of sars. the use of gloves, gowns, goggles, and caps was significantly associated with a reduced risk for acquiring sars, but the high degree of collinearity in the use of these precautions made it difficult to ascertain which measure was most important. other findings included an increased risk for sars among health care workers who perceived there to be an inadequate supply of personal protection equip-ment and among those who received less than hours of sars infection control training. based on these studies and on the fact that the patterns of transmission of sars suggest droplet and contact modes of transmission, one can suppose that isolating patients with sars and implementing droplet precautions using surgical masks and contact precautions for all persons interacting with them are likely sufficient to prevent the transmission of sars from these patients to others. however, despite the lack of definitive studies showing an involvement in transmission through fomites, routine environmental cleaning and disinfection also should be completed; % sodium hypochlorite, % ethanol, and % phenol have all been shown to inactivate sars-cov within minutes [ ] . in addition, because of potential for possible airborne transmission associated with aerosolgenerating procedures and because airborne transmission cannot be ruled out altogether in some cases occurring in the recent outbreak, the use of n respirators and negative pressure rooms (when available) is likely prudent until further studies better define the role of possible airborne transmission. whether n respirators require fit-testing needs further study, as described earlier. in addition to the protective measures described earlier, given the reported cases of through-precautions transmissions, additional measures to reduce the opportunity of transmission also should be enforced. these include minimizing the number of health care workers and visitors permitted in the patient's room, minimizing the time spent by health care workers and visitors in the room and specifically minimizing the time spent in close contact with the patient, keeping to the side of the patient (out of direct droplet range), only having the most experienced personnel perform procedures on the patient, providing adequate medication to suppress cough and vomiting with the goal to minimize droplets produced from the patient, and avoiding transporting patients with sars when possible. furthermore, ensuring an adequate supply of protective equipment and providing intense training with regard to its appropriate use is important, as documented by lau et al. [ •] . an additional component to controlling the spread of sars is tracing all close contacts of symptomatic sars patients, isolating those who are symptomatic, and quarantining those who are asymptomatic for the -day incubation period after their exposure. such measures were instituted in many of the countries involved in the recent outbreak, including china, taiwan, hong kong, singapore, and canada. however, given the limited understanding of transmission that existed at the beginning of the outbreak, in some areas of the world close and remote contacts of symptomatic and asymptomatic patients with sars were quarantined, as opposed to limiting quarantine to only close contacts of symptomatic patients with sars, who are now appreciated as being the only contacts that have significant risk for acquiring the disease. in taiwan, by the end of the epidemic, , people had been placed in quarantine, with failure to comply punishable by fines of $ to $ and incarceration of up to years [ ] . in beijing, approximately , residents were quarantined in their homes or quarantine sites [ •] . these numbers would be lower had quarantine been limited to only close contacts of symptomatic cases. in beijing, by limiting quarantine in this way, the number of persons quarantined would have been reduced by approximately % [ •] . typically, quarantined persons were asked to stay where they were quarantined, wear surgical masks when near others, take their temperature two to three times a day, and seek medical attention promptly if they developed fever (≥ ° c) or other symptoms compatible with sars. phone calls or visits from public health officials occurred regularly to check on the status of quarantined persons. the use of quarantine as a strategy in the control of infectious diseases is controversial given the ethical and legal issues regarding its negative associated impact on civil liberties. in addition, the effectiveness of quarantine has been questioned because of the difficulty of tracing all atrisk contacts and ensuring observance of the rules of quarantine in all quarantined persons. as a strategy in the control of sars specifically, one could argue that the effectiveness of quarantine should be further questioned given the lack of evidence of transmission during the incubation period before the onset of symptoms. however, the role of quarantine is not only to prevent transmission dur-ing the incubation period, should that be associated with a particular infection, but it also can facilitate early detection and management of symptomatic cases by enforcing compliance with reporting the onset of symptoms. in beijing, the effectiveness of quarantine is supported by the fact that no secondary transmission to relatives or other contacts was detected from any person who had sars while quarantined [ •] . analysis has shown that restricting quarantine in beijing to only those who had close contact with an actively ill patient with sars would not have compromised its effectiveness [ •] . the decision to implement quarantine needs to be made in conjunction with local public health authorities. in the event that the recognition of sars is delayed and an outbreak ensues that is not readily controllable using the aforementioned strategies alone, other additional control strategies should be considered in order to expedite control of the disease. central to this is the designation and coordination of an interdisciplinary outbreak team with excellent communication capabilities. decisions need to be made regarding implementation of more drastic control measures, such as hospital-wide screening and visitor restriction, closing hospitals, removing exposed or symptomatic groups to designated hospitals, or managing exposed or symptomatic cohorts in place. all of these strategies were used in different circumstances in singapore with positive effect [ ] . additional control measures to consider include airport screening and travel restrictions, although the usefulness of these strategies in terms of their contribution to the control of infectious diseases has not been systematically studied. sars has opened the world's eyes to the existence of emerging infectious diseases that have the capability of causing worldwide outbreaks within a relatively short span of time. given the threat of the return of sars and the ongoing threat of other emerging infectious diseases, it is prudent to consider a general paradigm shift regarding the approach to potentially infectious persons. implicit in this is the need to educate health care workers in addition to the general public. health care "new normal" directives implemented in ontario, canada that suggest addressing all patients presenting with respiratory illness as potentially infectious until proven otherwise and that reinforce that ill health care workers should stay at home until they are well are an example of the implementation of this paradigm shift [ ] . in addition, "healthy habits" posters directed at the general public and created by the us centers for disease control and prevention (cdc) in atlanta, georgia are an excellent example of the kind of basic health hygiene education that should be reinforced [ ] . in so doing, the goal is to change the way that infectious diseases are managed in health care and by the public, in order to increase the emphasis on the prevention of transmission of such diseases, with the ultimate goal of possibly averting a worldwide outbreak of the next newly emerged infectious disease. sars is a newly recognized infectious disease that caused a worldwide outbreak affecting people in countries from november through july . studies have shown that transmission occurs primarily through droplet and contact, but airborne transmission cannot be ruled out. superspreading events, although the exception to the rule, play a significant role in propagating transmission, especially in hospital settings. control depends on the identification of cases and early implementation of isolation and appropriate personal protective measures, contact tracing, and possibly the implementation of quarantine for asymptomatic contacts. these were the measures that permitted the control of the worldwide to outbreak and will hopefully prevent another outbreak from becoming as widespread, should sars re-emerge. papers of particular interest, published recently, have been highlighted as: • of importance •• of major importance world health organization: who issues a global alert about cases of atypical pneumonia world health organization: summary of probable sars cases with onset of illness from world health organization: sars: breaking the chains of transmission world health organization: severe acute respiratory syndrome (sars) in singapore--update world health organization: sars case in laboratory worker in taiwan world health organization: update --review of probable and laboratory-confirmed sars cases in southern china world health organization: new case of laboratory-confirmed sars in guangdong this is an excellent description of the molecular evolution of sars-cov based on the sars outbreak in china isolation and characterization of viruses related to the sars coronavirus from animals in southern china this is the first report of the isolation and characterization of sars-cov-related viruses from animals in southern china prevalence of igg antibody to sarsassociated coronavirus in animal traders--guangdong province, china this seroprevalence study determined that a small proportion of healthy persons in hong kong had been exposed to sars-covrelated viruses at least years before the recent sars outbreak sars--one year later why sars will not return: a polemic the big question now: will it be back? science • world health organization: consensus document on the epidemiology of severe acute respiratory syndrome (sars) this is an excellent summary of the understanding of the epidemiology of sars clinical progression and viral load in a community outbreak of coronavirus-associated sars pneumonia: a prospective study detection of sars coronavirus in patients with suspected sars interpretation of diagnostic laboratory tests for severe acute respiratory syndrome: the toronto experience cluster of sars among medical students exposed to single patient this is a retrospective cohort study analyzing risks for transmission of sars among medical students exposed exclusively to the first sars patient in the prince of wales hospital in hong kong before his illness was recognized illness in intensive care staff after brief exposure to severe acute respiratory syndrome this is a retrospective analysis studying the risk for transmission of sars among intensive care staff after a brief unexpected exposure to a patient with sars in probable secondary infections in households of sars patients in hong kong this is a retrospective analysis describing risk factors for secondary infection occurring in households and household members of patients with sars in hong kong this is a retrospective cohort analysis describing risk factors for transmission of sars among nurses who worked in two critical care units with sars patients in toronto first data on stability and resistance of sars coronavirus compiled by members of who laboratory network sars transmission among hospital workers in hong kong this is a case-control study of hospital workers with sars and matched controls assessing risk factors for transmission of sars in hong kong guideline for isolation precautions in hospitals transmission of the severe acute respiratory syndrome on aircraft possible sars coronavirus transmission during cardiopulmonary resuscitation cluster of severe acute respiratory syndrome cases among protected health-care workers transmission dynamics and control of severe acute respiratory syndrome transmission dynamics of the etiological agent of sars in hong kong: impact of public health interventions lack of sars transmission among healthcare workers, united states lack of sars transmission among public hospital workers sars infection among health care workers in beijing, china healthcare worker seroconversion in sars outbreak secondary household transmission of sars introduction of sars in france sars transmission, risk factors, and prevention in hong kong investigation of a nosocomial outbreak of severe acute respiratory syndrome (sars) in toronto, canada this is a description of the risks associated with four superspreading sars events occurring in beijing epidemiology and cause of severe acute respiratory syndrome (sars) in guangdong, people's republic of china severe acute respiratory syndrome combining clinical and epidemiologic features for early recognition of sars this is an excellent description of a strategic framework for the early recognition of sars public health guidance for community-level preparedness and response to severe acute respiratory syndrome (sars). supplement i: infection control in heathcare effectiveness of precautions against droplets and contact in prevention of nosocomial transmission of severe acute respiratory syndrome (sars) this is a case-control study of noninfected and infected staff members from five hong kong hospitals with documented exposures to index patients with sars use of quarantine to prevent transmission of severe acute respiratory syndrome--taiwan efficiency of quarantine during an epidemic of severe acute respiratory syndrome this is a description of the efficiency effectiveness of quarantine during the sars outbreak in beijing sars transmission and hospital containment new normal" directives to healthcare facilities centers for disease control and prevention: healthy habits to stop germs at home, work and school key: cord- -kxwgpymq authors: webster, robert g.; peiris, malik; chen, honglin; guan, yi title: h n outbreaks and enzootic influenza date: - - journal: emerg infect dis doi: . /eid . sha: doc_id: cord_uid: kxwgpymq ongoing outbreaks of h n avian influenza in migratory waterfowl, domestic poultry, and humans in asia during the summer of present a continuing, protean pandemic threat. we review the zoonotic source of highly pathogenic h n viruses and their genesis from their natural reservoirs. the acquisition of novel traits, including lethality to waterfowl, ferrets, felids, and humans, indicates an expanding host range. the natural selection of nonpathogenic viruses from heterogeneous subpopulations cocirculating in ducks contributes to the spread of h n in asia. transmission of highly pathogenic h n from domestic poultry back to migratory waterfowl in western china has increased the geographic spread. the spread of h n and its likely reintroduction to domestic poultry increase the need for good agricultural vaccines. in fact, the root cause of the continuing h n pandemic threat may be the way the pathogenicity of h n viruses is masked by cocirculating influenza viruses or bad agricultural vaccines. i nfluenza is an ancient disease that has infected humans at irregular intervals throughout recorded history ( ) . while the "spanish" influenza is the best recorded catastrophic influenza pandemic, similarly severe pandemics occurred earlier, when the human population of the world was much smaller, and they will occur again. our challenge is to understand all aspects of the influenza virus, the hosts and their response, and the virus' global impact so that we may be better prepared to face the inevitable next influenza pandemic. the influenza virus that appears most threatening is the avian h n strain that since has infected > persons in vietnam, thailand, and cambodia and has killed more than half of them. nonetheless, the h n influenza threat is viewed with disturbing complacency; a frequently heard statement is "since the virus has not adapted to continuing human-to-human transmission by now, it is unlikely to do so in the future." such complacency is akin to living on a geologic fault line and failing to take precautions against earthquakes and tsunamis. influenza a viruses are perpetuated in the wild birds of the world, predominantly in waterfowl, in which the subtypes (which differ by % in their hemagglutinin [ha] nucleotide homology) coexist in perfect harmony with their hosts ( , ) ( figure ). in these natural hosts, the viruses remain in evolutionary stasis, showing minimal evolution at the amino acid level over extended periods. this fact indicates that the influenza-bird association is ancient; this lack of change is surprising because influenza viruses are segmented, negative-stranded rna viruses that have no quality-control mechanisms during replication and are highly prone to variation. after transfer to a new type of host, either avian or mammalian, influenza viruses undergo rapid evolution. however, all ha subtypes, including h and h , have until recently been considered to be benign in their natural hosts. this benign equilibrium between the influenza virus and its host may have changed. before , no evidence had indicated that h influenza viruses could infect humans and cause fatal disease. the h influenza viruses were known to cause conjunctivitis in humans, and serologic studies provided evidence of subclinical human infection with the subtypes prevalent in avian live poultry markets ( ) . the precursor of the h n influenza virus that spread to humans in was first detected in guangdong, china, in , when it caused a moderate number of deaths in geese and attracted very little attention ( ) . this goose virus acquired internal gene segments from influenza viruses later found in quail (a/quail/hk/g / [h n ]) and also acquired the neuraminidase gene segment from a duck virus (a/teal/hk/w / [h n ]) before the goose virus became widespread in live poultry markets in hong kong and killed of infected persons ( , ) . this h n virus was eradicated by culling all domestic poultry in hong kong, and the genotype has not been detected since that time. however, different reassortants continued to emerge from goose and duck reservoirs ( ) that contained the same h ha glycoprotein but had various internal genes. the h n viruses continued to evolve, and in late , a single genotype was responsible for killing most wild, domestic, and exotic waterfowl in hong kong nature parks ( , ) . this genotype of h n spread to humans in hong kong in february , killing of infected persons ( ) , and was the precursor of the z genotype that became dominant. the z genotype spread in an unprecedented fashion across southeast asia, affecting vietnam, thailand, indonesia, cambodia, laos, korea, japan, china, and later malaysia. further analysis showed that the h n influenza viruses that caused outbreaks in poultry in japan and korea were genetically different from those in the other countries (the v genotype) ( , ) . the phylogeny of the recent z genotype viruses showed that viruses isolated in vietnam and thailand formed a cluster that remained distinct from those isolated in indonesia. to date, > million domesticated birds have been killed by the virus or culled to stem its spread; as of december , > persons have been infected in vietnam, thailand, indonesia, cambodia, and china, and have died ( in vietnam, in thailand, in indonesia, in cambodia, and in china). these recent h n influenza viruses have acquired the unprecedented and disturbing capability to infect humans; to cause neurotropic disease and a high proportion of deaths in waterfowl in nature; to cause death in and be transmitted among felid species, including domestic cats ( ) ; and to cause neurotropic disease and death in ferrets and mice ( ) . these incremental changes intensify concern about this h n virus' pandemic potential. these traits are likely to have been acquired initially by reassortment in and , when a plethora of different genotypes were detected in poultry markets and later in farms in hong kong ( ) . these genes were presumably acquired from viruses found in waterfowl in southeast asia, but the actual gene donors have not yet been identified. since late , the z genotype has become dominant, but phylogenetically distinguishable viruses have continued to cocirculate in indonesia and western china. these characteristics have been acquired mainly through mutations in the rna polymerase (pb ) gene, insertions in the ha gene, and deletions in the na and nonstructural (ns) genes. thus, the h n viruses continue to evolve, initially by reassortment and more recently by mutation and deletion ( , ) . while most h n influenza viruses isolated from avian species in asia since are highly pathogenic in gallinaceous poultry, they show heterogeneous pathogenicity in other species. in domestic ducks, the pathogenicity of the h n viruses varies from high to nonpathogenic. in ferrets, most avian isolates replicate and cause respiratory tract infection, while a few strains are highly pathogenic and neurotropic (causing hind leg paralysis), and the virus has been isolated from the brain ( ) . in contrast, all isolates from humans are highly pathogenic to ferrets. a similar pattern is found in experimental infection of mice, in which most avian isolates cause respiratory infection. were the highly pathogenic h n viruses transferred within and between countries by persons, poultry, or fomites? in previous outbreaks of highly pathogenic h and h infection in multiple countries, the spread was directly attributable to humans. the main way influenza a nonpathogenic h influenza virus is believed to have spread to domestic ducks and geese, then to domestic chickens. in chickens, the h virus became highly pathogenic before it was transferred back to domestic ducks and geese. the highly pathogenic h virus reassorted its genome with those of other influenza viruses in aquatic birds, and the resulting viruses spread to domestic poultry farms, humans, and occasionally to pigs. these viruses acquired mutations in their pb , ha, na, and ns genes that made them lethal to domestic and wild waterfowl and humans. solid lines, transmission demonstrated; dotted lines, transmission postulated but not demonstrated. multiple opportunities exist for control of highly pathogenic avian influenza: ) prevent contact between wild and domestic poultry by use of screened poultry houses and treated water; ) prevent contact between domestic waterfowl and gallinaceous poultry by use of screened houses and treated water and by exclusion of waterfowl from "wet markets"; ) eradicate h /h influenza viruses from gallinaceous poultry by culling or the use of vaccines that prevent disease and transmission; ) prevent contact between poultry, pigs, and humans and make vaccines and antiviral drugs available. virus is spread in poultry is by movement of poultry and poultry products; establishing good biosecurity measures on poultry farms is therefore an important defense. the poultry industry is a huge, integrated complex in asia, and a number of firms have branches in china, vietnam, thailand, and indonesia. nonetheless, the involvement of multiple lineages of h n argues against human-mediated spread from a single source. live poultry markets are an amplifier and reservoir of infection ( ) the migrant ducks that commonly wander through rice fields scavenging fallen rice seeds are another potent mechanism for the spread of infection. after late , when h n viruses had killed waterfowl in kowloon park in hong kong, most avian h n isolates isolated in vietnam, thailand, and indonesia were highly pathogenic to chickens and domestic ducks. however, by late and early , some avian isolates were nonpathogenic to ducks but retained their pathogenicity to chickens ( ) . genetic analysis of these isolates showed evidence of multiple variants within single specimens ( ) . on madin-darby canine kidney (mdck) cells, these viruses formed a mixture of small and large plaques that had different biologic properties. viruses that formed large plaques were usually highly pathogenic to ducks and ferrets, whereas viruses that formed small plaques were usually nonpathogenic to both birds and ferrets. some virus isolates formed small plaques that were pathogenic to ducks. thus, plaque size was not a marker of pathogenicity. when ducks were orally infected with the original mixed population of h n viruses, most birds died, but some excreted virus for an extended period (up to days); during this time, viruses that were nonpathogenic to ducks were selected. serologic testing of these ducks showed hemagglutination inhibition (hi) and neutralizing antibodies against the original dominant virus in the mixture; thus, immune clearance had caused the selection of the minor variants. the viruses shed on day had become nonpathogenic to ducks, although they remained highly pathogenic to chickens. sequence analysis of the ha showed that these viruses differed from the original dominant virus at multiple amino acids and were antigenically distinguishable in hi tests. therefore, h n viruses circulating in avian populations in southeast asia are clearly heterogeneous. notably, this phenomenon has repeatedly been reported for other influenza viruses that are in the process of altering their interspecies transmission, including european avian h n viruses that were transmitted to pigs ( ) , h n viruses that were transmitted to pigs and humans, and now h n viruses that are transmitted from ducks to humans. how these mixtures of codominant viruses are generated in a quasispecies is unresolved. suggested mechanisms include mutator mutations or partial heterozygotes, but a satisfactory explanation is not available ( ) . a subdominant population of h n viruses is presumably selected in ducks after the immune response clears the dominant virus. the subdominant population appears to be uniformly nonpathogenic to ducks, as if this is the natural situation for influenza in the duck. whether further selection will occur against the polybasic cleavage site in the ha and the pathogenicity determining sites in pb and ns remains to be seen. these viruses' loss of pathogenicity to ducks, but retention of pathogenicity to chickens and presumably to humans, has been a problem associated with their eradication. in vietnam, for example, disease signs were used as the criteria for identifying h n infection in ducks. thus, the duck has become the trojan horse of highly pathogenic h n influenza in asia ( ) . migratory waterfowl are generally believed to be the main reservoir of all subtypes of influenza a viruses, including h and h subtypes. however, less agreement is found regarding the role of migratory waterfowl in the initial spread of highly pathogenic h n viruses across eastern asia in . the isolation of highly pathogenic h n from herons, egrets, and peregrine falcons in hong kong in and leaves no doubt that wild migratory birds can be infected and may spread disease to local poultry flocks. the outbreak in qinghai lake ( , ) proves that these highly pathogenic h n influenza viruses are transmissible among migratory waterfowl. the migration route of shorebirds in the east asian-australasian flyway does overlap the areas that have had h n outbreaks, although the virus has been notably absent in taiwan, malaysia (except for occasional outbreaks near the thai border), and western australia (figure ). the role of migratory birds in the transmission and spread of highly pathogenic h n viruses is still unclear. however, the recent outbreak of h n infection in bar-headed geese and other species in qinghai lake is a cause for concern because these birds migrate southward to the indian subcontinent, an area that has apparently not been affected by h n avian influenza. if the virus were to become entrenched in india, its geographic range would be substantially extended, and the pandemic threat would increase accordingly ( ) . a mutation in the pb gene (residue e k) associated with pathogenicity in mammals ( , ) has been found in viruses isolated from birds in qinghai lake; this finding has caused concern that this mutation will be transferred to other migratory birds (e.g., wild ducks) and will be spread because not all infected birds die. although culling domestic poultry to contain the spread of highly pathogenic h n virus is considered an acceptable agricultural practice, culling migratory birds is not acceptable to any international authority (food and agriculture organization of the united nations [fao], the world organization for animal health [oie], the world health organization [who]). the idea of culling migratory birds must be strongly discouraged, for it could have unknown ecologic consequences. instead, since highly pathogenic h n has been demonstrated in migratory birds, the poultry industries of the world must adapt measures such as increased biosecurity (figure ), the use of vaccines, or both. early detection and aggressive control measures allowed japan, south korea, and malaysia to eradicate h n virus soon after its introduction into those countries' poultry flocks, demonstrating that rapid and determined responses can keep the virus from gaining a foothold. in other countries in asia, delayed detection and response caused the virus to become entrenched across a wide region, and eradication at this stage has become a formidable undertaking. the need for h n vaccines for domestic poultry is increasing. adopting a policy to use vaccines in poultry is an important decision for agricultural authorities in countries such as thailand (a major poultry exporter) and vietnam. both countries are investigating their specific needs. while considerable data exist on the efficacy of influenza vaccines in domestic chickens, little comparable information is available regarding ducks. the pros and cons of the use of vaccines in poultry have been reviewed ( ) . current technologies permit discrimination between vaccinated and naturally infected birds; however, vaccines are not standardized on the basis of antigen content. "good" and "bad" agricultural vaccines are in use. good agricultural vaccines provide protection from disease despite lack of a close antigenic match between the vaccine and circulating strain and reduce the virus load below the level of transmissibility. they do not provide sterilizing immunity: vaccinated birds may excrete low levels of virus after challenge infection. sentinel unvaccinated birds are kept in each house to monitor for virus shedding, antigenic drift, or both. bad agricultural vaccines prevent disease signs but do not prevent shedding of transmissible levels of virus. they also promote undetected spread of virus on farms and to live poultry markets and promote antigenic drift. china and indonesia have adopted poultry vaccination to control h n , and vietnam has begun vaccine trials in poultry. however, the resurgence of h n in indonesian poultry and pigs ( ) and the detection of h n in apparently healthy birds in live poultry markets in china ( ) suggest that some vaccines are of suboptimal quality or that coinfection masks disease. the adoption of a vaccine strategy for h n virus in mexico in the s reduced disease signs but has not eliminated the h n virus from the region; instead, vaccination may have contributed to the virus' widespread presence in central america and to its antigenic drift ( ) . the clinical signs of infection with highly pathogenic h n virus may be masked by cross-protection by other influenza subtypes, but this fact is often overlooked. during the initial outbreak of highly pathogenic h n in hong kong in , chickens in the live poultry markets exhibited no disease signs, yet samples from apparently healthy chickens, ducks, and quail showed highly pathogenic h n in each of the poultry markets surveyed ( ) . surveillance showed that multiple influenza subtypes were cocirculating, including lineages of h n , the first represented by the g lineage (a/quail/hong kong/g / [h n ]) and the other by g (a/chicken/hong kong/g / [h n ]). the g lineage has the same internal gene segments as the index h n human isolate (a/hong kong/ / [h n ]) and is believed to have been the donor of these genes during reassortment that produced the original h n human strain in ( ) . in laboratory studies, chickens previously infected with h n (a/quail/hong kong/g / [h n ]) were protected from disease signs and death when challenged with highly pathogenic h n , but the chickens shed h n virus in their feces ( ) . further studies in inbred chickens established that the cross-protection was due to cell-mediated immunity and that it could be transferred by cd + t cells but not by antibodies ( ) . the possible effect of cocirculating influenza viruses on the pathogenicity of highly pathogenic h n in vietnam, thailand, and elsewhere in asia has not been resolved. to date, no other subtypes of influenza a viruses have been reported in poultry in vietnam or thailand. surveillance of live poultry in hong kong and in nanchang ( ) suggests that other influenza a viruses are cocirculating in live poultry markets and on duck farms. definitive information is required to understand the ecology of influenza and the possible masking of disease signs caused by h n . conventional wisdom about pandemic influenza holds that a pandemic is inevitable and that the only question remaining is "when?" the h n virus continues to evolve and spread, with additional human infections occurring in vietnam, cambodia, indonesia, china, and thailand. if this virus acquires human-to-human transmissibility with its present fatality rate of %, the resulting pandemic would be akin to a global tsunami. if it killed those infected at even a fraction of this rate, the results would be catastrophic. while the high pathogenicity of the qinghai bar-headed goose isolate is a continuing threat to poultry and humans, perhaps the most insidious threat comes from unobserved transmission through wild and domestic ducks. the isolation of h n virus from bar-headed geese in qinghai lake in southern china in originated from unobserved infection in poultry markets and suggests that highly pathogenic h n viruses continue to circulate unseen among poultry in china ( ) . we cannot afford simply to hope that human-to-human spread of h n will not happen and that, if it does, the pathogenicity of the virus will attenuate. notably, the precursor of the severe acute respiratory syndrome (sars)-associated coronavirus ( ) repeatedly crossed species barriers, probably for many years, before it finally acquired the capacity for human-to-human transmission, and its pathogenicity to humans was not attenuated. we cannot wait and allow nature to take its course. sars was interrupted by early case detection and isolation, but influenza is transmissible early in the course of the disease and cannot be controlled by similar means. just year before the catastrophic tsunami of december , asian leaders rejected a proposed tsunami warning system for the indian ocean because it was too expensive and the risk was too remote. this mistake must not be repeated in relation to an h n avian influenza pandemic. we must use this window of opportunity to prepare and to begin prepandemic implementation of prevention and control measures. fields virology evolution and ecology of influenza a viruses a review of avian influenza in different bird species pandemic influenza: a zoonosis? isolation and characterization of prevalent strains of avian influenza viruses in china a pandemic warning? avian influenza in hong kong emergence of multiple genotypes of h n avian influenza viruses in hong kong sar re-emerging h n influenza viruses in hong kong in are highly pathogenic to ducks investigation of outbreaks of highly pathogenic h n avian influenza in waterfowl and wild birds in hong kong in late re-emergence of fatal human influenza a subtype h n disease characterization of h n influenza a viruses isolated during the - influenza outbreaks in japan genesis of a highly pathogenic and potentially pandemic h n influenza virus in eastern asia avian h n influenza in cats lethality to ferrets of h n influenza viruses isolated from humans and poultry in highly pathogenic h n influenza virus infection in migratory birds avian flu: h n virus outbreak in migratory waterfowl the impact of a monthly rest day on avian influenza virus isolation rates in retail live poultry markets in hong kong are ducks contributing to the endemicity of highly pathogenic h n influenza virus in asia? role of domestic ducks in the propagation and biological evolution of highly pathogenic h n influenza viruses in asia recent influenza a (h n ) infections of pigs and turkeys in northern europe independence of evolutionary and mutational rates after transmission of avian influenza viruses to swine microbial adaptation and change: avian influenza bird flu spreads among java's pigs effect of vaccine use in the evolution of mexican lineage h n avian influenza virus characterization of avian h n influenza viruses from poultry in hong kong characterization of an avian influenza a (h n ) virus isolated from a child with a fatal respiratory illness cross-reactive, cell-mediated immunity and protection of chickens from lethal h n influenza virus infection in hong kong poultry markets protective cross-reactive cellular immunity to lethal a/goose/guangdong/ / -like h n influenza virus is correlated with the proportion of pulmonary cd + t cells expressing gamma interferon the influenza virus gene pool in a poultry market in south central china isolation and characterization of viruses related to the sars coronavirus from animals in southern china we thank carol walsh for manuscript preparation and sharon naron for editorial assistance. influenza viruses in wild aquatic birds and their role in the evolution of new pandemic strains for humans and animals. key: cord- -nfdplszh authors: wong, lai-yi; leung, ping-chung; pang, suet-yee; cheng, king-fai; wong, chun-kwok; lam, wai-kei; fung, kwok-pui; lau, tak-fai; tse, yee-kit; kwok, chi-yui title: a herbal formula for prevention of influenza-like syndrome: a double-blind randomized clinical trial date: - - journal: chin j integr med doi: . /s - - - sha: doc_id: cord_uid: nfdplszh objective: to investigate the efficacy of a herbal formula in the prevention of influenza or influenza-like syndrome among elderies residing in old-people’s home in hong kong. the secondary objectives are to investigate the quality of life (qol) and symptomology changes among the herbal users and to evaluate the safety of this formula. methods: in ten old people’s home or community centres in new territories, hong kong, eligible subjects agreed to join the study and were randomized to receive a herbal formula or a placebo on alternate days over weeks. among those participants, had provided blood samples for immunological assessments before and after the study drug. assessments were done at , , and weeks. participants were instructed to keep a daily record of body temperature and any symptoms as sore throat, myalgia, running nose or cough, and to report to assessor accordingly. those reporting body temperature of . °c and above would be visited and a proper nasopharyngeal swab be taken for viral study. results: seventy-two participants developed influenza-like-symptoms but none of them was proven influenza in their nasopharyngeal swabs, of these patients belonged to the herbal group and to the placebo group, without significant differences between groups. the difference on the changes in qol between the two groups was not statistically significant. however, in the immunological study, the natural killer cell absolute count was significantly increased in the herbal group compared with the placebo group ( ± vs ± , p< . ). conclusions: the herbal preparation was not effective compared with placebo in the prevention of influenza-like syndrome. it was however safe and possibly supporting immunological responses. infection. ( ) the results of evaluation were encouraging: none of those using the herbal preparation contracted sars while . % of other health workers were infected. improvement of influenza-like symptoms and quality of life (qol) measurements were also observed. only less than % reported minor adverse events. ( ) the observation did not allow conclusive deductions since the trial was neither randomized nor placebo-controlled; and during the chaotic period of the deadly epidemic, measures to ensure a proper conduction of a trial were simply lacking. nevertheless, a study of the immunological state of % the herbal consumers indicated that there was objective evidence of improvement of body defense system after two weeks of treatment. interestingly, the boostering effect subsided two weeks later. ( ) we therefore consider that further exploration on the efficacy of the herbal preparation is justified and a plan for a proper randomized controlled trial is thus constructed. since the annual record of the department of health in hong kong, indicated that an endemic of influenza is likely to appear from february to april every year, a preventive program could be organized within this period accordingly. the primary objective of the study was to investigate the efficacy of the herbal preparation previously used for the prevention of sars against endemic influenza among a group of at risk elderly people. if unpredictabley, the annual endemic did not happen, the primary objective would have to be changed to the control of influenza like syndrome. the secondary objectives included the safety of using the preparation and the changes in the qol among the users. the study was designed as a double-blind, placebo-controlled, and randomized trial. the target participants were dwellers of old-age homes or attendance of elderly centre, aged or above. a total of elderly centres and old age homes were randomly selected from new territories, hong kong. the inclusion criteria included those enjoying stable health and had no influenza-like symptoms on enrollment. written informed consents were obtained from all the participants before entry into the study and the study protocol was approved properly by the clinical research ethics committee of the prince of wales hospital. exclusion criteria included history of hypersensitivity to herbs, regular consumers of other herbal preparations, medications that were known to upset the immuno-modulating function, e.g. steroids, and severe cognitive dysfunctions. only those who did not receive influenza vaccination in the past six months would be asked to join the blood sample group. the eligible participants were allocated randomly in a double-blind way to one of the two treatment groups according to a computer generated stratification randomized block design. the stratification was made on old-age home/elderly centre and vaccination status. in each old-age home or elderly centre the participants were randomized separately within the vaccinated group or non-vaccinated group to receive either herbal preparation or placebo. participants received the g sachet of herbal preparation or placebo on alternate days over weeks. after weeks, participants stopped taking either the herbal preparation or placebo but were followed up by research interviewers at the end of another weeks. the placebo was made of starch that was coloured to resemble herbal tea. in the -weeks study period, participants were instructed to keep a daily record of body temperature and any symptoms such as sore throat, myalgia, running nose and cough, which resembled symptoms of influenza. a research interviewer telephoned each participant twice a week to gather the update data, while individual participants was required to report to the interviewers any time when they suspected contraction of influenza-like illness. when the body temperature was more than . ℃, a naso-pharyngeal swab would be taken from the individual by the research nurse, and sent for viral investigation. influenza-like symptoms and adverse reactions were observed and qol was evaluated at the , th, th and th week. a subgroup was recruited for examination of the blood for immunological markers. total of participants who did not receive influenza vaccination within months before the study were recruited and consent on voluntary basis. they were required to give ml of blood each before and weeks after the administration of either herbal or placebo intervention. every herbal component was tested for heavy metals, microbial and pesticide contaminations and all test results met the safety requirements in hong kong. the formula was prepared as granules ready for consumption as a drink in a qualified laboratory licensed for good manufacturing practice in hong kong (chinese medicine industry development centre, hong kong institute of vocational education, hong kong, china). the formula contained commonly used herbs: morus alba l. . %, chrysanthemum morifolium ramat. . %, prunus armeniaca l. . %, forsythia suspense vahl . %, mentha haplocalyx briq. . %, platycodon grandi florum (jacq.) a. dc. . %, glycyrrhiza glabra l. . %, phragmites communis trin. . %, scutellaria baicalensis georgi . %, isatis indigotica fort. . %, astragalus membranaceus (fisch.) bge. . %, saposhnikovia divaricata (turcz.) schischk. . %. the placebo was manufactured in the same laboratory and the preparation matched the herbal drink satisfactorily in both colour and taste. the primary outcome was the number of episodes of influenza and influenza-like illnesses detected in the two different groups (incidence). influenza-like illness was defined by a fever over . ℃, plus presence of at least one of the influenza symptoms, e.g. sore throat, cough, running nose, or myalgia. for cases with fever, a nasopharyngeal swab was collected for the laboratory detection of influenza pathogens. the qol was evaluated using sf- questionnaire (vitality and mental health sub-scales) ( , ) and the immunological state was read from blood samples. immunological parameters included b lymphocytes, t lymphocytes, t-helper lymphocytes (cd ), t-suppressor lymphocytes (cd ) and natural killer (nk) cells. basic hematology (complete blood count and white blood cell), and biochemistry for renal and liver functions were included for safety studies. all data was managed using spss . software. the participants' demographics were first presented descriptively in overall and subgroups aspects. then parametric and non-parametric statistical analysis methods were used to test the change of health status, flu-like syndrome, immunological status, and safety profile before and after taking study drinks. intention-totreat analysis was applied. from dec to july , a total of , subjects were screened in elderly homes and elderly centres, and subjects met the inclusion and subjects agreed to join the study with the response rate of %. among the subjects, subjects agreed to provide blood samples for immunology assessments. before randomization, participants were randomly allocated into either the herbal or placebo group after recruitment and written consent signing. sixty-six participants drop out shortly after commencement, another participants drop out in the following visit and a total of participants ( . %) declined participation with . % and % respectively belonging to the herbal and placebo groups. reasons for withdrawals were related to personal preference and mild adverse events which are listed in the flow chart (figure ). at baseline, there were no significant differences between the herbal and the placebo groups. material including age, gender, habits of herb/dietary supplement intake and medical conditions are shown in table . also, the renal and liver functions of all participants who volunteered to provide blood sample for immunological assessment were within normal ranges. during the study period, for the first time in five years in the record of the department of health in hong kong, there was no outbreak of influenza endemic, either in the general family clinics of the department of health, or in the private sector. our protocol that was designed to meet the endemic therefore the study had to be modified to target on control of influenza-like syndrome, of participants ( . %) reported to us about fever and symptoms resembling influenza, however, their nasopharyngeal swabs showed negative results in the viral cultures. there was no statistical difference in fever occurrence between the herbal and placebo groups [ ( . %) vs ( . %), table ]. and the symptoms such as running nose was less in the herbal group than in the placebo group (p= . , table ). the qol on mental health and vitality health were improved in both herbal and placebo groups during the treatment period and washout period (p< . , table ) , with no significant difference between the two groups. notes: student's t-test was used on continuous variable, χ test or fisher's exact test was used on categorical variable, twotailed, α= . ; : any fever in last weeks of treatment start; △ : missing cases (vaccinated /non-vaccinated cases). the vaccinated and non-vaccinated groups were compared for symptoms and improvement of symptoms after herbal drink. no significant difference was found between the two groups. there were participants in the herbal group and in the placebo group who were reported mild adverse effect. dizziness, headache, sputum, and diarrhea were the most common mild adverse effects. thirty-one ( . %) and ( . %) participants withdrew from the herbal and the placebo group respectively due to the mild adverse events. all mild adverse events subsided - days either in the dropout group and study groups probably because the reported symptoms were not directly related to the herbal preparation (table ). the anti-viral formula was created from the combination of two popular classic formulae, sangju decoction (桑菊饮) and yupingfeng powder (玉屏风 散) modified and supplemented with two other herbal items known to be anti-viral. this trial was designed according to the annual expectation of an influenza endemic which happened for consecutive years from - . for some uncertain reasons, the in participants who volunteered to have their blood checked before and after treatment, participants were lost to follow-up due to their personal reasons. thus, there were subjects providing baseline and post-study blood sample. in the immunological state, there were no different between groups at baseline. after -week-treatment, the nk absolute count was significantly enhanced in the herbal group (p< . , table ). other immunological parameters had no significant difference. the majority of subjects had received influenza vaccination within months before the study expected endemic did not occur during the trial. instead, the clinical trial had to shift the target from influenza prevention to the investigation on preventing influenza-like syndrome with herbal preparation. there is no apparent efficacy of the herbal preparation on the prevention of influenza like symptoms, the preparation showed only better effect than the placebo on nasal discharge. similar to the results from our previous study using the same herbal preparation during the sars crisis, objective data on immunological modulation showed clear superiority of the herbal preparation over placebo. in another trial on healthy volunteers aiming at the behavior of immunomodulating indicators, i.e., t cells and b cells in the lymphocyte series, the results were also positive. ( ) the series of objective data supporting the immuno-modulating efficacy of the herbal preparation threw optimism on the further research of using herbal preparations for the prevention or treatment of influenza or influenza-like upper respiratory viral infection. the direction would include the optimization of the herbal formula, by varying the components of the formula, or better still, by identifying the effective fraction from the gross extraction of the formula. the concept of disease prevention in herbal medicine is not one that follows the logic of immunization, which initiates a prolonged state of positive immuno-defense. instead, the mechanism of action could be very much of a short term boostering of the immunological sensitivity which would be beneficial for the early control of an invading viral infection at its early stage. while seasonal influenza vaccination was highly recommended to prevent influenza and its complications, especially to high risk groups, such as healthcare workers, chronic illness, pregnant women, children less than years, elderly persons aged above years. ( ) the cost-effectiveness analysis and reports pronounced the vaccination program could reduce both health-care costs and productivity losses associated with influenza illness. ( , ) while most developed country and area like united states, united kingdom, canadian, australia, including hong kong had implemented national vaccination programs against influenza annually in the form of free or subsidized offer to the high risk groups, the community acceptance of pre-pandemic influenza vaccination was rather low. ( ) ( ) ( ) ( ) in the / swine influenza vaccination program among developed countries, due to the low take-up rate, the over abundance of unused vaccine ended up with inevitable destruction. ( , ) with the rising popularity of herbal medicine, some of the known antiviral activities, immuno-supportive and symptom relieving effects, our herbal formula could be offered as a viable option by itself or as an adjuvant to the vaccination program. clinical observation on patients . of severe acute respiratory syndrome treated by integrative traditional chinese medicine and western medicine influenza a (h n ) in hong kong: an overview. mortality associated with influenza and respiratory syncytial virus in the united states the use of an herbal formula by hospital care workers during the severe acute respiratory syndrome epidemic in hong kong to prevent severe acute respiratory syndrome transmission, relieve influenza-related symptoms, and improve quality of life: a prospective cohort study immunomodulatory effects of a traditional chinese medicine with potential antiviral activity: a selfcontrol study sf- health . survey-manual and interpretation guide tests of scaling . assumptions and construct validity of the chinese (hk) version of the sf- health survey in seasonal influenza (flu)-key facts about seasonal flu vaccine a meta-analysis of . effectives of influenza vaccine in persons aged years and over living in the community cost-effectiveness of influenza vaccination for elderly people living in the community opposition to swine flu vaccine among . health staff and the public seems to be growing worldwide the public's acceptance of novel . vaccines during a pandemic: a focus group study and its application to influenza h n willingness of hong kong healthcare workers to accept pre-pandemic influenza vaccination at different who alert levels: two questionnaire surveys acceptability of a/h n vaccinatin during pandemic phase of influenza a/h n in hong kong: population based cross sectional survey $ m lost as h n vaccine to be dumped millions of swine flu vaccine doses have expired . and will be burned all authors disclose no conflicts of interest in this work. key: cord- - e z p authors: li, kui-wai title: the economic strategy for the hong kong sar: evidence from productivity and cost analysis date: - - journal: journal of asian economics doi: . /j.asieco. . . sha: doc_id: cord_uid: e z p abstract by using a growth accounting framework for the period – , this paper estimates hong kong's total factor productivity and unit labor cost of twenty industries classified into three economic sectors of tradable goods, tradable services and non-tradable services. the results show that hong kong's total factor productivity has fallen in the s. the competitiveness of the three sectors of tradable goods, tradable services and non-tradable services has increased, remained unchanged and declined, respectively in the last two decades. policy recommendation for hong kong will be to aim for a supply-drive strategy so as to broaden the economic base. after becoming a british colony in , hong kong became an important trading and re-export hub. over the years, hong kong had acted as a ''shelter'' receiving a large number of natives fleeing from mainland china in pursuit of political stability and economic opportunities. hong kong's economic openness and desire to attain economic security enabled hong kong to supply goods and services to the rest of the world. the rise in income and demand was the result of the successful outcome of the supply-driven economic strategy. on july , , hong kong became the special administrative region (sar) of the people's republic of china. the central people's government in beijing adopted the ''one country, two systems'' approach in the post- hong kong. since , hong kong experienced economic revival and wealth appreciation, but the rapid growth was soon fuelled with speculation in stocks and properties in the early s, resulting in the economic bubble that eventually burst after the outbreak of the asian financial crisis (afc) in - . the economic problem facing the post-afc hong kong economy was structural imbalances with unemployment rate exceeding % in . such short-term fiscal incentives as the creation of temporary employments and assistance to small-and medium-sized industries have been introduced. after the outbreak of the severe acute respiratory syndrome (sars) in the spring of , additional demand-driven solutions aimed to revive the hong kong economy, including the entry of visa-free mainland travelers and the conclusion of two closer economic partnership agreements in and that permitted tariff-free exports of goods and services to mainland were introduced. economic optimism resulting from demand-driven policies has picked up and it is expected that when the new disney theme park opens in september , the hong kong economy would have recovered considerably. table shows that hong kong's macro-economy generally performed better in s than in s, and the first half of s was better than the second half of s. strong reexports growth lasted till the first half of the s, and export of services maintained high. growth in domestic investment remained robust in the - decade. the average real gdp growth maintained at . % in the s and . % in the s. beginning from the early s, despite the large total export to gdp ratio, domestic export could not keep pace with its growth rate. post-afc economic solutions advocated by the free-market school (enright, scott, & dodwell, ; wong & tao, ; imai, ) supported demand-driven policies and argued that the hong kong economy can recover along with the rest of the world as the linked exchange rate shielded hong kong from price differentials. on the contrary, structural or supply-driven advocates (dodsworth & mihaljek, ) noted the structural imbalance and believed that hong kong's economic advantage can further be eroded as economic situation in southern china strengthened. this paper expanded the data used in imai ( ) and followed the classification of economic sectors used in wong and tao ( ) , and extended the empirical analysis by comparing total factor productivity (tfp) with unlit labor cost analysis. the empirical analysis show strongly that structural rigidity rests largely on the non-tradable service sector. for hong kong to achieve economic revival, economic recovery is the first step, but resources reallocations to the more competitive tradable industry and service sectors will strengthen hong kong's advantage and expand hong kong's economic base and capacity. the results clearly show the vulnerability and insufficiency of the demand-drive school, and demonstrate that it would be the successful application of supply-driven policies that could lead the hong kong economy to a new stage of achievement. by using economic data from the two decades of - , this paper first uses the national accounting approach to work out hong kong's economy-wide tfp. the economywide capital stock will then be disaggregated to examine the tfp of major economic sectors (tradable goods, tradable services and non-tradable services). section discusses the debate in relation to hong kong's economic recovery. section uses the national accounting framework to work out the economy-wide tfp. sections and examine the tfp and unit labor cost of the three economic sectors, respectively. section suggests policy recommendations and concludes the paper. the description and construction of data are shown in the appendix a. there are four related arguments in the demand-driven school (imai, ; enright et al., ; wong & tao, ) . adherence to the advantages of the free market laissezfaire system has enabled the hong kong economy to recover along with the rest of the world according to the cyclical movements. the demand-driven nature of the hong kong economy resulted from the experience of the s and s when hong kong simply drifted along with or responded to the world demand of light manufacturing exports. since the s, demand has shifted to producer services. secondly, the linked exchange rate system adopted since can shield hong kong from loss in competitiveness because price differentials will eventually be adjusted through the current account. the linked exchange rate system can automatically adjust the hong kong dollar prices of tradable goods and services. thus, hong kong's tradable sectors remained price competitive despite wage increases. the rise in price of non-tradable sector is simply the result of expansion in the tradable sector, and a strong domestic demand is reflected in the increase in the value-added content of the non-tradable sector. thirdly, hong kong's advantage lies in its ability to provide business clusters that keep hong kong competitive despite the low production cost in southern china. cost of production becomes secondary if business opportunities are good and profits are made. the international, open and free nature of hong kong is itself a powerful competitive edge that few economies in the neighboring economies possess. the classification of services shall not exclusively be considered as consumption good. since the work of one producer can improve or add value to the work of another producer, goods and services have usage in both consumption and production. it is true that with the reallocation of hong kong manufacturing plants to southern china, hong kong firms have become service firms and provide services to the manufacturing sector. economic reform in mainland china has speeded up hong kong's transformation to a manufacture-related service centre. thus, while hong kong loses her comparative advantage in manufacturing, hong kong has gained new advantage in producer services. producer services contain the output of those industries producing intermediate inputs (for example, business services, wholesale) and some fraction of those industries that are consumer-based (for example, restaurants, hotels and transportation). the estimates in wong and tao ( , tables . - . ) show that producer services is the largest sector and experienced the largest annual average growth rates. for example, the share of the four producer services (business services; transport, storage, and communications; import and export; and finance) accounted for % of producer services in (wong & tao, , p. ) . in terms of average annual growth rates in - , producer services experienced a largest increase of . %, followed by government services of . %, consumer services of . % and manufacturing of À . %. wong and tao ( , p. ) concluded that hong kong has transformed from an ''enclave'' economy into a ''metropolitan'' economy. the supply-driven school (dodsworth & mihaljek, ) acknowledged the fundamental importance of the free market mechanism, but noted the structural imbalance and believed that the high cost can erode hong kong's economic competitiveness, which is defined as ''the degree to which domestic products and services can be marketed profitability.'' hong kong's robust economic performance since the conclusion of the sino-british negotiation in has led to wealth appreciation and income expansion, but the emergence of short-term investment behavior since the mid- s concentrated mainly in speculative activities in stocks and real estates. by the mid- s, the hong kong economy was speculation-led, characterized by a falling level of domestic exports and rising cost. statistics on wage increase showed that in the period - , tradable goods have twice experienced a two-digit wage increase in both current and constant price terms, while such non-tradable services as electricity and gas, transportation, and storage and communication, have experienced a total of four or five occasions of two-digit wage increase in both current and constant price terms (li, ) . hong kong's economic structural rigidity is the result of two separate economic trends (li, ) . on the one hand, sharp expansion in speculative activities boosted the nominal economy that merely involved monetary transactions. on the other hand, industrial hollowing and the fall in domestic exports resulted in the shrinkage of real economic activities that involved a reduction in employment, industrial output and exports. when the economic bubble burst, the structural imbalance was exposed when the shrinking real economy could not support the collapse of the nominal economy. differentiating the cobb-douglas production function that specified a relationship between aggregate output (y) and the three factors of capital stock (k), quantity of labor (l) and level of technology (a) with respect to time and dividing the result by y, a production function can be constructed as follows: ( ) where f k and f l are the factor marginal products and g represents technological progress or an estimate of tfp, commonly known as the solow residual. let s k = (f k k)/y and s l = (f l l)/y represent the shares of capital and labor factor payment in total output, respectively. a constant return to scale means that s k + s l = . the value of tfp can thus be calculated from eq. ( ) if all the other variables are known. the capital stock figures are estimated from the following equation: where rni is real net investment, which is real gross investment less depreciation. hong kong's aggregate output can be measured by the production-based real gdp. the gdp deflators are used in deriving the real figures expressed in constant prices. the capital stock figures are constructed from the accumulation of gross investment. real gross investment consisted of the gross fixed capital formation in the private sector, which included non-residential building, other construction, real estate developer's margin and all machinery and equipment, and change in stocks, expressed in constant prices. a depreciation rate of % is assumed, and the initial capital stock (in which is the earliest year when the gross fixed capital formation figures are available) is set equal to five times the value of the gross fixed capital formation (kim & lau, , appendix a). the labor input is measured by the number of working hours (h). employment in each time period is simply the size of the registered labor force (l) less the unemployed. the total number of labor hours is total employment multiplied by the average number of working hours per time period (see appendix a). the labor variable can be constructed from eq. ( ) with u indicating the unemployment rate. the data on the compensation of employees are adjusted to include the self-employed. one assumption is that the share of self-employed in the number of people engaged is the same in all industries. dividing the adjusted compensation of employee by the total valueadded in each industry gives the share of labor income. by deducting from unity the labor share in total factor payment gives the capital share in total factor payment. the constructed data (see appendix table a . ) shows that between and , production-based real gdp increased by %, while capital stock and labor increased by . and . %, respectively. table summarizes the total factor productivity estimates for the period - . output, capital and labor have grown by . , . and . %, respectively. output has experienced the highest growth in the - periods, with an average annual growth rate of %. capital experienced a higher growth rate in the s than the s, and the first half of the two decades showed a better performance ( . and . %, respectively) than the latter half ( . and . %, respectively). although the growth of labor is similar in the two decades, the growth rates in the - and - periods exceeded %. the shares of factor payment between labor and capital remained constant over the years. total factor productivity (tfp) shows an average of . % in the entire - decades, but its performance was higher in the period - (with . %) than other periods. in the overall and sub-periods, the contribution of capital to output is higher than labor. hong kong experienced high productivity growth in the second half of the s, but it has fallen considerably since the early s. despite a fall in the tfp in the two subperiods of - and - , contribution by capital ( . % as compared to . %) and labor ( . % as compared to . %) were similar. hong kong experienced a worse productivity rate (À . ) in the period - that covered the afc than the - period (À . ) during the sino-british negotiation. by contrast, labor's contribution increased to . % in the - periods, suggesting that labor productivity increased when unemployment increased and cost fell. the twenty industries in hong kong are classified under eight major categories by the government. the tfp of manufacturing improved strongly in the first half of the s, while the performance of most services deteriorated in the s, especially after the afc. these twenty industries can be classified into three economic sectors of tradable goods, tradable services and non-tradable services as follows: tradable goods sector: manufacturing; mining and quarrying. tradable services sector: import/export trade; hotel; storage; financing (banking + finance and investment companies + stock, commodity and bullion brokers, exchanges and services + financial institutions); insurance; business services (rental of machinery and equipment + business service other than rental of machinery and equipment); land transport (land passenger transport + supporting services to land transport + land freight); water transport (ocean and coastal water transport + inland water transport + supporting services to water transport); air transport; and other transport services. non-tradable sector: construction; electricity, gas and water; wholesale; retail; restaurants; communication; real estate; and community, social and personal services. the output of tradable goods sector reached its peak in with a share of . %, but by the late s it fell to around % (see appendix table a . ). output of tradable services sector has expanded most in real terms as its percentage share has doubled in the two decades (from . % in to . % in ) , and since it has exceeded the percentage share of non-tradable services that declined from % in to about % in . the tfp of the three economic sectors is shown in table . the tradable goods sector, which is largely dominated by manufacturing, enjoyed a positive tfp growth rate in all periods, giving an average of % in the - period with a higher rate in the s ( . %) than the s ( . %). the tradable services sector has a lower tfp growth rate, but remained positive except in the period - , giving an average of . % in the two decades of - . contrary to the tradable goods sector, the tfp growth rate for the tradable services sector is higher in the s ( . %) than the s ( . %), suggesting the sum of the last three columns should equal to the first column; any difference is the result of rounding off. that tradable services expanded mostly in the s. the performance of the non-tradable services sector showed a negative tfp growth rate in most periods and a negative average (À . %) in the whole - periods. and in the afc period of - , the positive tfp growth rate of . % could have produced by a fall in the growth rates of both capital and labor. the demand-driven advocates (wong & tao, , appendix a) emphasized the rapid expansion of producer service industries, but noted the difficulty in deciding on the choice of producer services. both the definition and the estimation of the proportion of producer services are subject to debate. producer service is defined by subtracting the nominal values of consumer services and government services from the nominal value-added of total services. the percentage calculations are based on rough estimations, but are highly questionable (as reproduced in appendix table a . ). for example, all hotel services are regarded as producer services, but hotels accommodation is demanded by tours to hong kong that are consumer related. in the case of storage facilities, an assumption of % consumed as producer service suggested that the rest of % would be used for consumption purpose by private individual households. the estimates based on the division between tradable producer services and nontradable producer services as conducted in wong and tao's ( ) can be repeated by using the data and the calculations from table . table shows the tfp growth rates of tradable producer services and non-tradable producer services using the percentage shares between the consumer and producer components in each of the service industry given in appendix table a . . real output growth shown in the first column is much higher in the tradable producer services ( . %) than the non-tradable producer services ( . %). capital stock grew much faster in the tradable producer services ( . %) than the non-tradable producer services ( . %). the tfp calculations also differed considerably. other than the period the sum of the last three columns should equal to the first column; any difference is the result of rounding off. - , the total factor productivity growth rates of tradable producer services were positive in all other periods, giving an overall of . % for the sample period. in the case of non-tradable producer services, other than a large percent growth of % in - , tfp fell in the decade of - . the entire s showed a score of . %, followed by a score of À . % in the s, giving an overall average of . % for the entire sample period. the tfp growth rates increased rapidly in - when both the growth rates of capital (À . %) and labor (À . %) fell, suggesting that a drop in factor inputs could lead to a rise in productivity. these estimates show that even with the use of wong and tao's ( ) classification, the tradable producer services were more competitive than the non-tradable producer services. labor productivity is indicated by the ratio of real output and the number of persons engaged, while the unit labor cost is the ratio of the payroll per person and labor productivity. labor productivity in the tradable goods sector, which is shown in fig. , has been rising since , while unit labor cost maintained a stable trend until the late s. as hong kong's manufacturing industries have migrated to southern china beginning from the mid- s, demand for industrial workers in hong kong has fallen, and only those efficient and productive workers can remain in the industry. the stable unit cost trend shows that the increase in output came mainly from productivity. thus, the improvement in labor productivity has maintained hong kong's competitiveness in the manufacturing sector. fig. gives a mixed picture for the tradable services sector. labor productivity has shown an overall rising trend, but unit labor cost has also caught up significantly and remained high until the late s. tradable services probably faced a competitive world price, and the economic overheating in the first half of the s has pushed up the unit labor cost. the fall in demand and price in tradable services after the afc, however, could have led to a considerable fall in unit labor cost. the picture shown in fig. on the non-tradable services sector suggests that while the labor productivity trend in the entire period showed only a one possible explanation on the high unit labor cost and low labor productivity in the non-tradable services sector could be their monopolistic position that shielded them from international price competition. the price and cost movements of non-tradable services tended to be rigid downwards, and that their monopolistic nature enabled them to increase price faster during the boom time, but was reluctant to let price to fall in a recession time. in the tradable goods sector, manufacturing definitely showed an improvement in labor productivity, as the number of workers has fallen and unit labor cost has fallen since the early s. in the tradable services sector, labor productivity has risen in import/export trade, hotel, storage, financing and water transport. the tradable services industries that showed a trend of rising unit labor cost included business services, land transport, and air transport. the industries that showed a mixed trend included insurance and other transport services. in the non-tradable services sector, those industries that showed a clear trend of rising unit labor cost include real estate, community, social and personal services, restaurant and retail. in construction, labor productivity showed a declining trend, while unit labor cost showed a rising trend. in electricity, gas and water, labor productivity rose significantly after . the result of these two industries may not reflect the true picture, as there is deficiency in the data on the number of persons engaged. communication and wholesale are the two industries that showed a rising trend in both labor productivity and unit labor cost. in wholesale, unit labor cost has a higher overall trend. the geometric average performance of unit labor cost growth rates in the second half of the s ( ) ( ) ( ) ( ) ( ) ( ) for the sectors and individual industries are summarized in table . given the outbreak of the afc in - , one would expect to see a fall in the unit cost in the second half of s. in the non-tradable services sector, the geometric average still showed an increase in unit labor cost by an average of . %, while both tradable services sector and tradable goods sector experienced an average fall of . and . %, respectively. price in the non-tradable services sector was rigid downwards, while the fall in the unit labor cost of tradable goods and services were in line with the movement of international prices. while the hong kong is linked to the us currency, the devaluation of major regional currencies had meant that the price of hong kong imports has fallen, and that would lead to a fall in price and deflation. with the exception of mining and quarrying that occupied only a small portion of gdp, individual industries that showed a positive geometric percentage growth in unit labor cost belong mainly to the non-tradable services (construction; community, social and personal services; real estate; restaurant and wholesale) and some tradable services (insurance; land transport; other transport services; business services and financing). those industries that experienced a fall in the unit labor cost are mainly the tradable goods and tradable service industries. among the twenty individual industries, eleven of them showed an increase in the geometric average unit labor cost, and the average percentage increase is . %. the large increase in construction pushed up this percentage. by contrast, the average of the nine industries with decreases in unit labor cost is À . %. the large percentage change can be due to the initial low wage paid to workers. in construction where sub-contracting is common, for example, a considerable amount of the cost would have taken up by the middlemen, while the actual wage paid to the construction workers is low. figs. and show the labor productivity and unit labor cost calculation using wong and tao's ( ) definition of tradable producer services and non-tradable producer services. in fig. , both labor productivity and unit labor cost have risen. although labor productivity leveled off in the late s, it kept rising until . on the contrary, the unit labor cost has risen rapidly in the late s but has declined since . in fig. , labor productivity has remained static with only small improvements since and a downward readjustment in . the unit labor cost of non-tradable producer services kept increasing in the entire period, except a small v-shape recovery during the afc. the rise in unit labor cost was not matched by a rise in labor productivity, suggesting that this sector was losing its cost competitiveness. by using a standard cobb-douglas production function for the two decades of - , this paper shows that hong kong's tfp has declined since the early s, and has reached negative growth rates in the second half of the s. hong kong has experienced an undisturbed period of robust economic growth until the outbreak of the afc in / . the estimates on the labor productivity of twenty individual industries show that the non-tradable services have performed poorly, and their unit labor cost has expanded. one can conclude that the solution to hong kong's economic problem rests on the unit labor cost and the uncompetitive nature of many non-tradable services. in the case of manufacturing industries, the high productivity suggested that new investments in hong kong's manufacturing sector could take place, though hong kong will not only confine to labor-intensive industries anymore. given the increasing role of the service economy, the expansion of the tradable services, including the tradable producer services, will be most suitable for hong kong, as it development can raise domestic demand and employment in line with international competitiveness. although the economic downturn results in rising unemployment, unit labor cost has revised downwards through market forces. despite the short-term economic sacrifice, productivity in hong kong can be improved in line with wage revision and new demands, both locally and internationally. hong kong needs to explore new economic channels, in addition to the various existing comparative advantages. this paper raises new questions on the relevance of sector composition in hong kong industries. the debate between demand-driven and supply-driven policies can complement each other. a flexible economic structure facilitates the function of the free market. the flexible economic structure means that hong kong should pursue supply-side strategies, as the availability of additional resources can attract further demand. in policy terms, this requires the continued investment in infrastructure, investment in human capital and the provision of more resources, typically land resources that can promote the economic capacity of hong kong. a long-term strategy that projects a multi-dimension economy is more suitable than to use short-term policies to reduce temporary economic ills, and repetition in the use of short-term policies could deprive the benefits of a long-term policy. hong kong cannot be a national economy, but a diversified economic base permits productivity to improve both extensively and intensively. international economics of the city university of hong kong is gratefully acknowledged. the author is responsible for all remaining errors. the hong kong data used in this paper can be found in the author's own website at: http://fbstaff.cityu.edu.hk/efkwli/data.html. the gdp deflators are obtained from on the average hours per employee worked in the last working week of the time period are available in the labor statistics (international labor organization, various years). these figures are then multiplied by a total of . weeks ( / days) to obtain the average number of hours worked per employee per year. for the period - , the statistics on the median hours per employee worked in the last working week of each time period are available and obtained from the census and statistics department. a similar formula is applied to derive the annual statistics, and the median hours are assumed to equal to the average hours. the value-added figures of each economic sector are used in calculating the labor factor share. each economic sector's value-added is given by the compensation of employees and gross operating surplus. the former is mainly wage payment to workers, while the latter is the return to employers and entrepreneurs including self-employed workers. in order not to understate the share to labor factor payment, the compensation of the self-employed should be included in the compensation of employees. this is done by calculating the adjusted compensation of employees, which includes the original level of compensation of employees and the portion of compensation derived from the self-employed. the statistics on the number of self-employed for the period - can be obtained from the annual digest of statistics (census and statistics department, various years), and the figures before were extrapolated. the analysis assumes that the compensation of the selfemployed is the same as the employed. the share of labor factor payment is calculated from the rate of adjusted compensation of employees to the production-based gdp in current price. the composite deflator of domestic exports is used as the deflator for the tradable goods sector, while the composite deflator of exports of services is used for the tradable services sector. the deflator for the non-tradable services sector is the geometric difference of the gdp deflator and the tradable sector's deflator shown in gross domestic product (table , pp. - ) . the industry-specific implicit price deflator is the ratio of value index and industrial production index or volume index. manufacturing and mining and quarrying are the only two industries that used the industrial production index data. most service industries used the volume index data. there are some exceptions. in electricity, gas and water, data on the consumption of electricity and gas (ceic database) and the consumption index are used to replace the industrial production index. in the import/export trade, the proxy deflator is the weighted average of the deflators for domestic exports, retained imports, and exports and imports of trade-related services. the transportation sub-index in the hong kong composite consumer price index (cpi) is used as the proxy for the deflator for land transport. this covers fares for ferries, trains, taxis and public transport, motor licenses and insurance, parking fees and tunnel tolls. in the case of water transport, air transport and other transportation services, the proxy deflator is the weighted average of the deflators for exports and imports of transportation services. the weights used are their nominal shares in the exports and imports of transportation services. the deflator for storage is derived from the rental index for private flatted factories. the telephone service in the miscellaneous service index of the composite cpi is used as the proxy deflator for communication. the weighted average of the deflators for export and import of financial services and the deflators for export and import of insurance services are used as proxy deflators for financing and insurance, respectively. the implicit price deflator for real estate developers' margin is used as the proxy deflator for real estate. the implicit price deflator for the exports of other services is used as the proxy deflator for business services. for community, personal and social services, the proxy deflator is the miscellaneous services sub-index of the composite cpi. this covers school fees and education charges, medical services, entertainment expenses, household services, hairdressing, repairs of personal and household goods, subscriptions, and postal and telephone services. the proxy deflator for wholesale is the implicit price deflator of retained imports. the census and statistics department provides the estimate for the value of retained imports and its quantum index for the period - (hong kong monthly digest of statistics, december , pp. fa ). the difference in the value of imports and reexports gives the value of retained imports, and the value at current price can easily be transformed into value at price. the retained import value for the period - , however, is estimated from extrapolating the - data. the implicit price deflator is calculated from the values of retained imports at current price and at price. the industries that had experienced a rapid rise in inflation in the s include community, social and personal services, electricity, gas and water, land transport, restaurants, construction and real estate. all these industries belong to the non-tradable sector where competition is limited. labor productivity is the ratio of real output and the number of persons engaged, and a labor productivity index with as the base year is calculated (table a. ). the unit labor cost index with as the base year is the ratio of nominal payroll index per person engaged and the labor productivity index. the nominal payroll per person engaged equals to total value of payroll at current market price divided by total number of persons engaged. statistics on the production-based gdp at current market price ( gdp, tables - , pp. - ) are used to represent nominal output. the number of persons engaged (including individual proprietors and active partners) is end-of-year figures from the principle statistics shown in the annual digest of statistics. there are two exceptions. for electricity, gas and water, the number of persons engaged for water is not available; the figures used in the analysis contain the number of persons engaged in electricity and gas only. the number of persons engaged in construction is the number of persons engaged in construction sites only. since the reported number of persons engaged would be smaller than the actual number, the labor productivity so calculated could be biased upwards. nominal payroll statistics found in quarterly report of employment, vacancies and payroll statistics are used because they include wages and other related cash payments, namely, wages, overtime pay, shift allowance, attendance and efficiency bonuses, cost-of-living or dearness allowance, food and transportation allowances, year-end seasonal bonuses and payment in lieu of leave, and so on. the quarterly report of employment, vacancies and payroll statistics gives the nominal payroll index per person engaged in four different base years (june , march , march , and march , which are then converted into one standardized series with as the base year for all industries. in cases where industries are being grouped together, namely land transport, water transport, financing and business services, the overall nominal payroll index per person engaged is the weighted average of the indices of its constituents. the weights are the number of persons engaged in the constituents (table a. ). ( ), appendix a, p. - . gross domestic product, annual digest of statistics, various issues and quarterly report of employment, vacancies and payroll statistics, various issues, census and statistics department hong kong, china: growth structuralchang, and economic stability during the transition. occasional paper the hong kong advantage structural transformation and economic growth in hong kong: another look at young's hong kong thesis the sources of economic growth of the east asian newly industrialized countries the political economy of the pre-and post- hong kong capitalist development and economism in east asia: the rise of hong kong trade and development report an economic study of hong kong'sproducer service sector and its role in supporting manufacturing the author is indebted to the referees, manoranjan dutta, francis lui and hiroyuki imai for their comments on the earlier draft, participants in the hong kong economic association biannual conference in december and eric kwok for his research assistance. funding support from the apec study center and the research center for key: cord- -wu ygt w authors: tambyah, p. a. title: sars: responding to an unknown virus date: - - journal: eur j clin microbiol infect dis doi: . /s - - - sha: doc_id: cord_uid: wu ygt w the severe acute respiratory syndrome (sars) is an emerging infection caused by a novel coronavirus which first appeared in southern china at the end of . in early , through a single incident, it spread to hong kong, singapore, canada and vietnam. for busy clinicians in large public hospitals, the response to the virus was initially based on ensuring a high level of protection for staff. however, as the epidemic progressed and more information became available about the virus, procedures were rationalized and the virus is currently under control worldwide. there are, however, numerous unanswered questions concerning super-spreading events, the modes of transmission of the virus and, perhaps most importantly, the rapid detection of the virus early in the course of disease. these issues need to be addressed in case the virus becomes more widespread in the near future. the severe acute respiratory syndrome (sars) is a newly recognized coronavirus infection that emerged in southern china [ ] with subsequent global spread to countries [ ] [ ] [ ] [ ] . in countries where local transmission has occurred, hospitals have been the major foci of infection especially in singapore [ ] and canada [ ] . in february , reports began emerging on promed mail of an outbreak of atypical pneumonia in the guangdong province in southern china [ ] . it is now believed that the first cases of sars occurred in the city of foshan in the guangdong province [ ] . however, throughout november until the late part of february, sars was largely confined to the province of guangdong. the global dissemination of sars is believed to have begun on the ninth floor of hotel m in hong kong, where a physician from guangdong stayed for one night on february [ ] . at least individuals who were staying on the ninth floor of the hotel were subsequently infected with sars, although none of them reportedly had direct contact with the ill physician. the newly infected individuals traveled onward to their homes or next destinations in the usa, canada, singapore, hong kong and ireland sparking off epidemics of varying degrees of severity in each of those countries, mainly in hospitals but also in their respective communities. it is striking to realize that the entire global dissemination of this epidemic can probably be traced to this single event of one overnight hotel stay. it has almost become a cliché to report that the sars epidemic, the first emerging infectious disease of the st century, heralded an unprecedented collaboration between researchers across the globe. within weeks of the first cases, electronic publications reviewed the clinical syndromes [ , ] as well as the characteristics of the virus and methods for its detection by the polymerase chain reaction [ , ] . the genome of various strains of the virus were sequenced, which contributed tremendously to knowledge of its molecular epidemiology [ ] . there was an explosion of reports about the sars coronavirus, with more than a thousand publications available on pubmed by the beginning of march , the first anniversary of the global emergence of the virus. it is beyond the scope of this review to cover all of the virological and clinical information contained in these articles and i would refer the reader to the excellent review by peiris et al. [ ] . the present review focuses on the response to this emerging disease and its evolution in light of increasing information. outstanding issues that remain to be resolved are also highlighted. one of the first unusual aspects of this emerging infection was the recognition that healthcare workers (hcw) were uniquely susceptible to the then unknown etiologic agent. in hong kong, the first clue that a new infection had emerged was a cluster of ill hcws. the same was noted in vietnam and led to the world health organization (who) sending a team to vietnam under the leadership of dr carlo urbani, who later died from the virus he helped to define [ ] . as soon as sars was recognized as a nosocomial infection, guidelines were issued by various authorities including the who it is important to recognize that in the beginning of the sars outbreak there was no information about the agent responsible for the infection or its mode of transmission; hence, there was a tendency to "over-protect." as the epidemic evolved, so did the guidelines, which are constantly being updated and might indeed be out of date by the time this report is read. all guidelines are published on the internet [ - ], and the reader is encouraged to review the websites for the latest information. the physician from guangdong who became the source of the global epidemic through his stay at hotel m was admitted to a hospital in hong kong the day after his arrival in the city. he became progressively more ill and died days later. it is striking that although he was critically ill and intubated on a ventilator in the intensive care unit, only one hcw who attended to him in the emergency department became ill [ ] . the reason for this is likely that hong kong hospitals had been on the alert for highly pathogenic avian influenza. in february, there had been a small cluster of cases of avian influenza in a hong kong family that had traveled to mainland china [ ] . a directive had gone out from the hong kong department of health on february to maintain strict infection control with droplet precautions for all cases of "atypical" community-acquired pneumonia because of concerns that highly pathogenic avian influenza might be easily transmissible from person to person. one of the singaporean women who returned from hotel m was indeed isolated as a possible case of avian influenza in one of singapore's large general hospitals, and no secondary cases resulted from her. because of the concerns for possible avian influenza, or some unknown pathogen with an uncertain mode of transmission, most of the initial strategies devised for the prevention and control of sars were directed against a highly contagious airborne pathogen. in [ ] , previously healthy young people were infected and six died from highly pathogenic avian influenza in hong kong. this mortality rate ( %) is much higher than the normal mortality rate for influenza especially among young healthy individuals [ ] . in response to the outbreak, more than one million chickens were slaughtered and the disease was rapidly brought under control. seroepidemiologic studies of hcws done at the time [ ] demonstrated the efficacy of personal protective equipment (ppe) in preventing transmission and identified the risk associated with close personal contact in addition to the virus's lack of efficient humanto-human transmission capability [ ] . fears of a recurrence of a more virulent or easily transmissible form of avian influenza directed the initial efforts against sars. however, sars possessed an unusual quality in that it seemed to be transmitted in the healthcare setting far more efficiently than in households, where measles, varicella and other airborne viruses usually take rapid hold [ ] . this has yet to be explained completely, but it supports the argument that close contact is the major mode of transmission of the sars virus. fomites have been a cause for concern with the sars coronavirus since the initial global dissemination stemming from individuals in hotel m who had no direct contact with the index case but had stayed in the same corridor and probably had occasion to touch elevator buttons or railings that might have been contaminated with the sars virus. in the outbreak of sars in the amoy gardens apartments in hong kong [ ] , more than individuals who had no known direct contact were infected possibly through the aerosolisation of contaminated sewage. the implications of fomite transmission of sars are considerable and would mandate a much greater degree of environmental cleaning than is currently practiced. however, there are many unanswered questions in this arena. for example, why did the individuals staying on the same hotel floor as the index case in hotel m get infected but none of the staff? [ ] . sars has been convincingly demonstrated to be caused by a coronavirus [ ] . certain other characteristics have been ascertained from the previously known coronaviruses, e and oc , including their ability to survive after drying on inanimate surfaces in the hospital environment as well as differences in the viability of the virus at different conditions of temperature and humidity [ , ] . while the sars coronavirus has a certain amount of homology with the other pathogenic human coronaviruses [ ] , too little is known about its behavior under different environmental and atmospheric conditions to make a definitive statement about the role of the environment in nosocomial transmission. there have been reports of the sars coronavirus persisting for prolonged periods of up to days on environmental surfaces [ ] . survival in stool is reported to be even longer at up to days in alkaline diarrheal stools. this would certainly help explain such circumstances as the hotel m outbreak. the attack rates for sars have generally not been high. in singapore, for example, the index case for the national outbreak was nursed in a general ward by staff who were not wearing protective covering of any kind, and the attack rate was only / doctors, / nurses and / fellow patients in the same ward areas [ ] . again, the distribution of infections suggests that close contact is the most important factor leading to the transmission of this pathogen in hospitals. the widespread emphasis on ppe has been seen by some as placing an undue emphasis on hcw protection without adequately considering the protection of other at-risk individuals, such as other patients in the same area. the use of ppe is also not without its own adverse consequences [ ] as reactions to latex are common among hcws, some with serious consequences. it should also be noted that the use of respirators has been associated with fatal adverse events [ ] . costs are also an issue, and in resource-poor settings -ply cotton masks have been used, which have reportedly been effective in preventing the nosocomial transmission of the virus in at least one large public hospital [ ] . in a case-control study, seto et al. [ ] found that surgical masks were also effective in preventing transmission of sars to hcws, which is in line with our understanding of the epidemiology of the virus. in singapore, one of the successes of our approach to the control of sars was the widespread availability of full ppe for any staff member who requested it. this was even before the widespread dissemination of the virus led to the mandatory use of full ppe in all hospitals, and it provided staff the reassurance that their welfare was a high priority in the midst of an epidemic. there have been concerns that the use of n masks alone might not be adequate for preventing the nosocomial transmission of sars since cases have occurred among "fully protected" hcws [ , ] ; these cases possibly resulted from contact transmission. recognition of the role of contact transmission has led to the inclusion of recommendations for the use of gloves and gowns in all guidelines [ ] [ ] [ ] [ ] [ ] [ ] . while these garments have been shown to be effective in preventing the nosocomial transmission of other respiratory viruses [ ] , few data are available for their efficacy regarding sars. travel restrictions were among the more controversial aspects of the sars epidemic. the economies of most affected countries in east asia were devastated by these travel advisories. while other pathogens have been documented as being transmitted on airplanes, most notably influenza [ ] , the number of individuals infected with sars during air travel was remarkably low. according to the who [ ] , there have been flights carrying symptomatic probable sars patients and of those flights did not result in a single secondary infection. overall, cases of secondary infection resulted from symptomatic individuals. one flight alone, ca , which flew from hong kong to beijing on march, is now known to have accounted for of these cases. olson et al. [ ] reported that one flight with four symptomatic individuals with sars was associated with an attack rate (for confirmed sars) of zero while another flight with a single symptomatic individual was associated with an attack rate of %. the singapore experience [ ] was that three flights with symptomatic sars patients resulted in only one transmission. the overall attack rate for the flights into singapore was thus less than % despite one symptomatic individual being a so-called "superspreader" and another being critically ill at the time of the flight, requiring intubation soon after arrival. interestingly, olson et al. [ ] point out that fully % of the fellow passengers who became infected with sars had no direct contact, as defined by the who, with the index patient on their ill-fated flight. they do not offer any explanation for the differing attack rates, although a careful reader would realize that among the individuals allegedly infected on the flight, ten were traveling together as part of a tour group. also, the flight with the four symptomatic individuals was much shorter than the flight that was associated with widespread transmission. this is supported by icu data from canada [ ] that showed time of exposure to be a major risk factor. overall, however, what these reports demonstrate is that a much more detailed analysis is required in order to truly understand the epidemiology of this unusual virus. during the peak of the sars epidemic in china ( - april ), when the who had travel advisories and alerts in place, there were more than , visitors from china and hong kong [ ] who entered singapore and not a single case of transmission was recorded from any of these individuals. in taiwan, a strict -day quarantine [ ] was placed on all individuals returning from countries that were on the who list of sars-affected countries. a total of , individuals were quarantined, among whom had probable sars and only one of whom had laboratory-confirmed sars. thus, the detection rate was . % for probable sars and . % for laboratoryconfirmed sars. these figures have to be balanced against the costs and psychological impact of quarantine for more than , individuals who were perfectly well. thanks to excellent isolation and case finding with contact tracing, the number of people infected with sars with each successive generation of the outbreak was progressively reaching extinction levels [ ] in the sarsaffected countries. with the re-emergence of sars at the beginning of , drastic travel restrictions have fortunately not been instituted to date since there is no evidence yet of widespread dissemination of the virus across international air routes by travelers. it could also be argued that since we now have much better knowledge of the epidemiology of the virus, travel restrictions might not be necessary the next time around. all of the guidelines agree it would be ideal if patients with sars could be nursed in isolation rooms [ - ]. there are differences, however, in the recommendations for negative pressure with separate ventilation systems, and these perhaps reflect the differences in resources available for healthcare. one drawback of isolation rooms is that unless there are adequate nursing or medical resources, the degree of attention that the patient will receive in a single isolation room is obviously lower than in an open well-ventilated area. patients isolated for infection control purposes are known to be at risk for adverse events in hospital [ ] and this again has to be balanced against the benefits in terms of reduced nosocomial transmission. while all of the available evidence points to droplet and contact transmission, there is a possibility that the virus might be aerosolized during such procedures as high-flow oxygen therapy or possibly via the use of extractor fans, which were blamed for the aerosolisation of contaminated sewage during the amoy gardens outbreak [ ] . therefore, n respirators or higher should be used. this is a cause for concern as in many countries, including singapore, without adequate pre-prepared negative-pressure rooms, powerful extractor fans similar to the ones used in the bathrooms at the amoy gardens apartments are used to create a form of laminar uni-directional airflow. while these may serve to direct the flow of air away from areas of heavy traffic, it is possible that they might be hazardous by facilitating the aerosolisation of infectious droplets. in singapore [ ] and canada [ ] , transmission of the sars virus has been noted in crowded emergency rooms where patients routinely wait for hours for a hospital bed. in singapore, sars was documented as being transmitted to a patient's visitor who was waiting in a corridor during the patient's radiological procedure [ ] , again a common occurrence in many healthcare settings. in our own hospital, the national university hospital, the largest cluster of sars cases occurred in one of our eight-bed wards [ ] where patients are deliberately placed eight to a cubicle in order to support the philosophy of healthcare financing in singapore. the sars outbreak has clearly been a wake-up call for health authorities worldwide [ ] as they try to adjust health systems primarily designed to minimize costs into systems designed to protect staff and patients. the isolation and segregation of patients with suspect and probable sars has been credited with markedly reducing the transmission of the virus [ ] . lipsitch et al. [ ] reported a reduction in the time to isolation of patients with sars as the epidemic progressed with a corresponding decline in the number of secondary cases as knowledge of the virus increased. the majority of individuals with sars have not transmitted the virus to anyone [ ] . while it is tempting to ascribe this to infection control measures, many of these individuals were infected and hospitalized long before the institution of infection control methods. this has given rise to the concept of "super-spreaders." it is known that the presence of common viral upper respiratory tract infections can turn some hcws into so-called "cloud hcws" [ ] . these individuals have been linked with the airborne dispersal of agents that are normally only spread through contact, such as group a streptococci or staphylococcus aureus. the hypothesis is that the presence of upper respiratory tract infections transforms these individuals into efficient transmitters of pathogens through increased coughing, sneezing or nose rubbing. alternatively, airborne dispersal could result from the use of various respiratory therapies. the index patient for the singapore epidemic was not isolated, and hcws, visitors and fellow patients were infected [ ] . the second generation of cases associated with this cluster, before the institution of infection control practices or strict isolation, included only cases. the situation in canada was similar, with cases in the second generation occurring preisolation [ ] . it is quite clear, however, that non-isolated patients are hazardous to staff, visitors and other patients. single non-isolated patients have led to well-documented outbreaks in hospitals in singapore [ ] , taiwan [ ], canada [ ] and hong kong [ ] . the phenomenon of "super-spreaders" has been invoked to explain why so few transmissions resulted from the majority of non-isolated individuals while a few rare cases were associated with the vast majority of transmissions [ ] . the jury is still out as to whether these are indeed individuals who are for some reason more able to transmit infection or whether events, such as the use of high-flow oxygen therapy, are more responsible for what are probably more accurately described as "super-spreading events." until we have more virologic information, we have to assume that all individuals with sars are "super-spreaders" until proven otherwise and we have to take all the necessary precautions. again, because of the concern that an undiagnosed patient might turn out to be a "super-spreader," the threshold to isolation has become progressively lower. initially, hospitals and clinics were using the who case definitions of suspect and probable sars cases to determine which cases to isolate. as we, and others, have pointed out, atypical presentations [ ] are the achilles heel of such a strategy and these have been associated with significant nosocomial transmission. in a very important report from a sars screening clinic, rainer et al. [ ] pointed out that the who criteria, which were actually designed for epidemiologic purposes, while relatively specific, have a sensitivity of only about % in predicting which individuals will turn out to have sars. the implications are that a large number of individuals will need to be isolated and monitored very closely until their clinical course becomes evident. in practice in singapore, this resulted in the conversion of large numbers of hospital wards to isolation facilities, cancellation of elective surgeries and an overall paralysis of the healthcare system. we used a regime of -hourly temperature monitoring without any use at all of antipyretics together with daily serial chest radiographs and blood counts and comprehensive chemistry work ups. with this regime, we found a sensitivity of %, specificity of %, positive predictive value of % and negative predictive value of % for the who criteria at patient presentation [ ] . it is clear that an accurate rapid diagnostic test is urgently needed to allow us to filter out individuals who are at low risk of sars or, better still, at lower risk of transmitting the virus should they not be isolated. current diagnostic tests [ ] , which are based on either molecular methods or serological diagnosis, are severely limited not predominantly by sensitivity or specificity but by the fact that they take awhile to become positive, during which time widespread dissemination of the virus could have occurred from a single non-isolated "super-spreader." fever screening is widely practiced as a sars-prevention measure. there was even a period when the who called for fever screening at airports to prevent the global spread of sars. unfortunately, fever is a non-specific and insensitive screening tool for sars [ ] . atypical presentations of sars without fever have been reported especially in older and immunocompromised patients [ ] . one case is particularly illustrative [ ] . a -year-old man cleared a fever triage area in an emergency room as he was afebrile; he was then admitted to a general ward (not a "fever ward") as a case of heart failure, and he remained afebrile until he developed a lowgrade temperature after being transferred to the medical intensive care unit for progressive shortness of breath. two other patients, one visitor and one nurse who had been in the same emergency department area as this patient were infected with sars. the visitor, a previously healthy -year-old woman, died and her husband and son were subsequently infected. in the brief period the index patient was in the general ward, two other patients and the entire shift of nurses working in the ward at the time, who were only wearing n masks, were infected. by the time the patient became febrile in the intensive care unit, staff were wearing full ppe and no further infections resulted. thus, a single patient who "passed" two strict fever screens managed to be the source of at least nine infections in less than h. this patient was critically ill and died days later; thus, he may have had a very high viral load. this case illustrates the limitations of "cookbook screening" by using fever protocols without paying attention to a careful clinical history and physical examination. in this case, an alert cardiology team who re-did the patient's history and examination and performed a bedside echocardiograph to prove that he was suffering from pneumonia not heart failure made the diagnosis. during the sars outbreak, the inter-hospital transfer of patients in canada [ ] , taiwan [ ] and singapore [ ] was a very efficient means of dissemination of the sars virus. in singapore, on march, the decision was made to close one hospital to new admissions and to concentrate all sars patients there [ ] . this unfortunately led to patients recently discharged from this hospital being shunted to other hospitals and starting off epidemics there. now, in singapore, once a cluster of cases with even a low degree of suspicion is identified, the unit is "locked down" with no admissions, transfers or discharges in order to prevent a recurrence of the former situation. this strategy was also used successfully in vietnam to contain the sars virus, which led to vietnam being the first country to be declared free of local transmission of sars [ ] . while we have learned a tremendous amount in the brief period since sars first emerged in november , there are still a number of unresolved issues for practicing clinicians. the cases of sars in early have quashed hopes that the virus was "put back in the box," and in the formerly affected countries many clinicians are deeply worried about dealing with a devastating resurgence of the virus. i have a personal "wish list" of questions that i would like answered before too long. these include: what are the conditions required for the airborne transmission of the sars coronavirus? when can we be sure that transmission does not occur? when can we get a good rapid diagnostic test that is positive early in the course of the illness? what makes a super-spreading event? is quarantine really necessary? i can only hope that the answers to these and numerous other questions raised by infection control practitioners, hospital epidemiologists, infectious disease clinicians and researchers can be answered before we face the next sars outbreak or something worse! even as this is being written, avian influenza rampages across east asia affecting primarily birds, but also claiming the lives of more than individuals. if this becomes a pandemic form of influenza, sars will pale in comparison. epidemiology and cause of severe acute respiratory syndrome (sars) in people's republic of china a novel coronavirus associated with severe acute respiratory syndrome identification of a novel coronavirus in patients with severe acute respiratory syndrome a major outbreak of severe acute respiratory syndrome in hong kong identification of severe acute respiratory syndrome in canada clinical features and short-term outcomes of patients with sars in the greater toronto area update: outbreak of severe acute respiratory syndrome-worldwide comparative fulllength genome sequence analysis of sars coronavirus isolates and common mutations associated with putative origins of infection the severe acute respiratory syndrome sars in northern vietnam influenza a h n -hong kong special administrative region clinical features and rapid viral diagnosis of human disease associated with avian influenza a h n virus observations on mortality during the influenza pandemic risk of influenza a (h n ) among healthcare workers exposed to patients with influenza a (h n ), hong kong how contagious are common respiratory infections? clinical progression and viral load in a community outbreak of coronavirusassociated sars pneumonia: a prospective study newly discovered coronavirus as the primary cause of severe acute respiratory syndrome coronavirus-related nosocomial viral respiratory infections in a neonatal and pediatric intensive care unit: a prospective study survival characteristics of airborne human coronavirus e stability of sars coronavirus in human specimens and environment and its sensitivity to heating and uv irradiation severe acute respiratory syndrome (sars) in singapore: clinical features of index patient and initial contacts an epidemic of occupational allergy to latex involving healthcare workers emergency preparedness and response in israel during the gulf war description and clinical treatment of an early outbreak of severe acute respiratory syndrome (sars) in guangzhou, pr china effectiveness of precautions against droplets and contact in prevention of nosocomial transmission of severe acute respiratory syndrome (sars) control measures for severe acute respiratory syndrome in taiwan cluster of severe acute respiratory syndrome cases among protected health-care workers-toronto, canada prospective controlled study of four infection-control procedures to prevent nosocomial infection with respiratory syncytial virus an outbreak of influenza aboard a commercial airliner global surveillance for severe acute respiratory syndrome transmission of the severe acute respiratory syndrome on aircraft low risk of transmission of severe acute respiratory syndrome on airplanes: the singapore experience accessed use of quarantine to prevent transmission of severe acute respiratory syndrome-taiwan transmission dynamics and control of severe acute respiratory syndrome safety of patients isolated for infection control preventing local transmission of sars: lessons from singapore identification and containment of an outbreak of sars in a community hospital update: severe acute respiratory syndrome-singapore the sars outbreak: how many reminders do we need? cloud" healthcare workers update: severe acute respiratory syndrome-taiwan update: severe acute respiratory syndrome-toronto, canada sars experience at prince of wales hospital, hong kong atypical presentations of sars evaluation of who criteria for identifying patients with severe acute respiratory syndrome out of hospital accuracy of who criteria for sars was similar in a non-sars hospital in singapore crouching tiger, hidden dragon: the laboratory diagnosis of severe acute respiratory syndrome atypical sars in a geriatric patient vietnam-sars free key: cord- -qqcb uk authors: lekone, phenyo e. title: bayesian analysis of severe acute respiratory syndrome: the hong kong epidemic date: - - journal: biom j doi: . /bimj. sha: doc_id: cord_uid: qqcb uk this paper analyzes data arising from a severe acute respiratory syndrome (sars) epidemic in hong kong in involving cases. a discrete time stochastic model that uses a back‐projection approach is proposed. markov chain monte carlo (mcmc) methods are developed for estimation of model parameters. the algorithm is further extended to integrate numerically over unobserved variables of the model. applying the method to sars data from hong kong, a value of . with a posterior standard deviation of . was estimated for the basic reproduction number. an estimate of the transmission parameter at the beginning of the epidemic was also obtained as . with a posterior standard deviation of . . a reduction in the transmission parameter during the course of the epidemic forced the effective reproduction number to cross the threshold value of one, seven days after control interventions were introduced. at the end of the epidemic, the effective reproduction number was as low as . suggesting that the epidemic was brought under control by the intervention measures introduced. (© wiley‐vch verlag gmbh & co. kgaa, weinheim) severe acute respiratory syndrome, commonly known as sars, is a new viral respiratory illness caused by a coronavirus, called sars-associated coronavirus (sars-cov) (leung et al., ) . the disease was first identified in china's southern province of guangdong on november, and then spread rapidly throughout the world via air travel with the last known case with a symptom onset date of july identified in taiwan (chowell et al., ) . it is reported that the epidemic infected cases (with deaths), from a total of countries (chau and yip, a) . a large proportion of the morbidity and the mortality was borne by hong kong with a total number of cases and deaths occuring between february and may (leung et al., ) . some of the measures introduced by the hong kong authorities to combat the disease include among others, public service announcements, addition of sars to the list of notifiable diseases, a -week suspension of schools, introduction of health declarations for incoming residents and visitors, isolation of cases and home quarantining of close contacts and restrictions on their travel out of the country (chau and yip, a) . using discrete time data on an ongoing sars epidemic in hong kong, donnelly et al. ( ) estimated the mean and variance of the incubation time, time from admission to discharge and time from admission to death. these parameters were obtained using maximum likelihood estimation methods assuming a gamma distribution for each period with allowance for censoring due to incomplete observation. the estimate of the mean and variance of the incubation period was . days and . days, respectively. the estimated mean and variance of the admission-to-death time was . days and . days, respectively, and the estimated mean and variance of the time from admission to discharge was . days and . days, respectively. as pointed out by leung et al. ( ) , parameters above suffer from right censoring since they were obtained using data from an ongoing epidemic. to address the problem of censoring above, the authors re-estimated parameters above using complete data on all the cases. the data was completed by using laboratory verification tests on . % of the cases. they estimated the mean incubation period to be . ( . ) days (standard errors in brackets). they also estimated that the time from onset to recovery, and the time from onset to death each followed a gamma distribution with mean . ( . ) and . ( . ) days, respectively (standard errors in brackets). using parameters estimated by donnelly et al. ( ) and weekly data on an ongoing sars epidemic in hong kong, riley et al. ( ) estimated the basic reproduction number (r ) from a discretized stochastic meta-population seir model as . with a % confidence interval of ( . , . ). it is evident that estimates obtained by leung et al. ( ) are different from those obtained donnelly et al. ( ) and as such the estimate of . above may be biased as it was obtained using estimates obtained with right censored data. it is imperative that a better estimate of the basic reproduction number would be obtained by using estimates obtained by leung et al. ( ) are different from those obtained donnelly et al. ( ) and as such the estimate of . above may be biased as it was obtained using estimates obtained with right censored data. it is imperative that a better estimate of the basic reproduction number would be obtained by using estimates obtained by leung et al. ( ) . by studying the exponential growth at the beginning of the epidemic and by estimating the generation time, lipsitch estimated r to be between . and . . using a likelihood-based approach on an ongoing epidemic, wallinga and tenius ( ) estimated r to be between . and . . mcbryde et al. ( ) applied bayesian inference techniques to estimate the basic reproduction number and other epidemiological determinants from data arising from a sars epidemic in shanzi province of china. they estimated r to be . with a % credible interval of ( . , . ). in this paper, a slight variation of the model by riley et al. ( ) is formulated. the model is used in conjunction with gamma distributions estimated by leung et al. ( ) and sars data from hong kong that is well documented by leung et al. ( ) . interest lies in estimating the transmission parameter, the basic reproduction number, and assessing whether control interventions were successful in controlling the epidemic or not. markov chain monte carlo methods are used for numerical integration over the distribution of unobserved variables which in this article is the series of unobserved new cases. the modelling approach used is different from the one by mcbryde et al. ( ) and uses a different data set. the paper is organized as follows; epidemiological features of sars and the hong kong data are discussed in the next section with the model presented in section . the bayesian inference algorithm using markov chain monte carlo methods is discussed in section with applications to simulated data and observed hong kong data discussed in section . a discussion of the paper is given in section . the disease is transmitted via close person-to person contact with infected individuals (chowell et al., ( ) . in general, sars begins with a high fever, with other symptoms including headache, an overall feeling of discomfort, and body aches. some people also have mild respiratory symptoms at the outset while most patients develop pneumonia. an individual exposed to sars becomes infectious after an incubation period of - days (chowell et al., ) . once infectious, individuals remain so for - days before they recover, although about % or more die (chowell et al., ) . circumstantial evidence suggests that, in most cases, infectiousness coincides with clinical symptoms (leung et al., ; riley et al., ) . here we study data from the sars outbreak in hong kong which is well documented by leung et al. ( ) . the data consist of three time series (see figure ) recorded from february to july , namely daily counts of sars cases by date of symptom onset ( cases), daily counts of deaths from sars ( deaths) and daily recoveries from sars ( recoveries). it is also documented that the first case of sars in hong kong showed symptoms on february, and was subsequently hospitalized on february (leung et al., ) . the last patient with sars first experienced symptoms on may and was hospitalized on june (leung et al., ) . on june , the world health organization removed hong kong from its list of areas with recent local transmission of sars (leung et al., ) . it is suggested by chau and yip ( a) that control interventions were initially introduced on or around the th of march when there was a formal recognition of an outbreak in a hospital, with more measures being put in place thereafter. the epidemic lasted for about days with control measures being introduced about days after the start of the epidemic. in this section, a slight variation of the model by riley et al. ( ) is considered. riley et al. ( ) used a discretized stochastic metapopulation seir model with a gamma distribution (formulated as a sum of exponential distributions) used for the waiting time in each disease compartment. the model considered here is a single population version of the model of riley et al. ( ) with a back-projection method (brookmeyer and gail, ) , used instead of a gamma distribution represented as a sum of independent exponential random variables. the single population model is motivated by the complete sars data discussed in the previous section and by the fact that it requires less detail to specify and less data for inference as compared to the model of riley et al. ( ) . a description of the model is as follows; assume that an individual is susceptible (s) until exposed to infection. once infected an individual goes through an exposure stage (e) where they are not infectious followed by an infectious (i) stage where they are classified into two categories ði À Þ and ði þ Þ. the classification is based on whether an infectious individual will proceed to die ðr À Þ with probability p or proceed to recover ðr þ Þ with probability À p. let t e ; t þ and t À represents the time spent in class e; i þ and biometrical journal ( ) i À , respectively. let f t ¼ pðt e ¼ tÞ; g þ t ¼ pðt þ ¼ tÞ and g À t ¼ pðt À ¼ tÞ be probability distributions for the time spent in each disease class. let m e and s e represent the mean and variance of t e , respectively and define m þ ; s þ ; m À and s À , similarly. consider a time interval ðt; t þ h where h represents the time interval at which measurements are taken, here h ¼ day. let bðtÞ; cðtÞ; d þ ðtÞ and d À ðtÞ denote the number of individuals exiting class s; e; i þ and i À during the time interval ðt; t þ h, respectively. let bðtÞ be the time dependent infection rate and define pðtÞ ¼ À exp À bðtÞ n hiðtÞ iðtÞ ¼ i þ ðtÞ þ i À ðtÞ and n is the population size, as the probability that a susceptible individual will get infected in ðt; t þ h. the rationale for the form of pðtÞ is given in lekone and finkenstådt ( ) . let rðtÞ be the number of cases who recover or die at time t. given initial conditions sð Þ ¼ s ; eð Þ ¼ e and ið Þ ¼ a, the discrete time stochastic model is then given by eðt þ hÞ ¼ eðtÞ þ bðtÞ À cðtÞ ; iðt þ hÞ ¼ iðtÞ þ cðtÞ À d þ ðtÞ À d À ðtÞ ð Þ notations bin ðn; qÞ and po ðmÞ represent a binomial distribution with parameters n and q (success probability) and a poisson distribution with mean m, respectively. the back-projection approach (brookmeyer and gail, ) is used in the previous equation to construct the means for the poisson distributions. this approach has been shown to be successful in epidemic modelling (becker, watson and carlin, ; becker und xu, ) and particularly in reconstructing sars epidemics (chau and yip, a, b) . introduction of control interventions will usually reduce the transmission parameter bðtÞ. capturing the change in bðtÞ as the epidemic progresses is made difficult by the fact that there is usually little or no information to be used to quantify the changes in the transmission parameter. riley et al. ( ) assumed for simplicity that bðtÞ took three different values on three equally spaced time periods over the whole observation period. choosing the number of change points may be difficult and as such modelling bðtÞ as described above may be difficult to implement. usually, the time at which control interventions are introduced is known. to avoid the problem of change points, it is assumed that the transmission parameter bðtÞ is constant up to the time point when the control measures are introduced and after that decays exponentially. this can be formulated as follows where t * is the time point at which control measures are introduced, b is the initial transmission rate and q > is the rate at which bðtÞ decays for t > t * . the same form of bðtÞ has been used successfully by lekone and finkenstådt ( ) to model control interventions in ebola epidemics and a similar form has been applied by chowell et al. ( ) . it should however be mentioned that this simple form of bðtÞ may not capture the heterogeneity in sars epidemics brought about by superspreader events (rare events where an individual may generate many more than the average number of secondary cases). thus, bðtÞ is used here for simplicity. the basic reproduction number r is defined as the average number of secondary cases generated by a primary case over his/her infectious period when introduced into a large population of susceptible individuals (diekmann, heesterbeek and metz, ) . the constant r thus measures the initial growth rate of the epidemic and for the model above it can be shown that (see riley et al., ) the time dependent effective reproduction number r ðtÞ ¼ bðtÞ ½pm À þ ð À pÞ m þ is the number of secondary cases per infectious case at time t and the time point at which r ðtÞ assumes values smaller than one indicates when control measures have become effective in controlling the epidemic. let t denote the end of the observation period and let b ¼ fbðtÞg t t¼ represent the time series of bðtÞ from the beginning to the end of the observation period and define c; d þ and d À similarly. the epidemic model specified in ( ) to ( ) together with the contact rate ( ) has parameter vector q ¼ fb; qg which we would like to estimate from knowledge of initial conditions, population size and from observation of fc; d þ ; d À g and from knowledge of p and the parameters of the distributions of t e ; t À and t þ . consideration of these data is motivated by the observed sars data discussed in the previous section. the time series fiðtÞg is in this case fully determined by iterating ( ) from the initial condition a. in reality, the series b is not observed. if b was observed, then the series fsðtÞg would be determined by iterating ( ) where bin ðx; n; pÞ represents a binomial distribution with parameters n and p and evaluated at the point x. the unobserved series b is imputed using mcmc methods which allow for numerical integration over the distribution of the unobserved process. proposals for b are generated and accepted according to a metropolis hastings step similar to the one described in lekone and finkenstådt ( ) . let w be the set containing means and variances of distributions of t e ; t þ and t À . by using the fact that bðtÞ; cðtÞ; d þ ðtÞ and d À ðtÞ are conditionally independent gives the augmented likelihood for the data as bin ðbðtÞ; sðtÞ; pðtÞÞ po ðcðtÞ; l t Þ po ðd À ðtÞ; h À t Þ po ðd þ ðtÞ; h þ t Þ where po ðx; mÞ represents a poisson distribution with mean m evaluated at the point x. multiplying ( ) by the prior pðqÞ gives, up to a constant of proportionality, the posterior distribution pðq; b j c; d þ ; d À ; wÞ / lðb; c; d þ ; d À ; w j qÞ pðqÞ ð Þ that we wish to sample from. an mcmc algorithm that samples in turn from the conditional distributions pðb j c; d þ ; d À ; w; qÞ and pðq j b; c; d þ ; d À ; wÞ produces draws from the desired pðq; b j c; d þ ; d À ; wÞ. preliminary analysis showed that a posteriori, the parameters b and q were correlated and this problem was overcome by updating them as a block rather than as single-site updates. the performance of the algorithm is tested by applying it to a simulated time series from the model ( )-( ) with parameter values s ¼ ; e ¼ ; a ¼ ; b ¼ : ; q ¼ : ; t * ¼ ; t e $ gð ; Þ; t þ $ gð ; Þ; t À $ gð ; Þ; p ¼ : and h ¼ . the notation gðb; cÞ represents a gamma distribution with mean b and variance c. a discrete approximation was used for the gamma distributions. these parameter values are, as far as possible, tuned to the data as they are motivated by earlier studies on sars and by what is known about its natural history (chowell et al., ; leung et al., ) . the simulated epidemic resulted in a final size (total number of susceptible individuals who get infected during the course of the epidemic) of with of the cases being fatal and having recovered by the end of the epidemic after t ¼ days. the mcmc algorithm is applied to the simulated data pretending that b is unobserved. initially, the performance of the back-projection method in reconstructing the series is inspected. in figure the simulated series c; d þ and d À are shown along with their means estimated via the back-projection method. figure suggests that the back-projection method produces sensible means in all the cases and hence a poisson distribution with this mean will be a reasonable way of rejecting/accepting proposals for b. inference is then conducted using two parameter sets for the prior distribution of b and q. at first, a non-informative prior set fb $ uð ; Þ; q $ uð ; Þg is used to run the mcmc algorithm followed by an informative prior set fb $ gð : ; : Þ; q $ gð : ; : Þg. the notation uða; bÞ represents a uniform distribution with parameters a and b. in each case, after discarding a burn-in period of , a sample of size taken every iterations of the chain was used to obtain posterior distributions. convergence was verified using convergence diagnostic measures and the chains were deemed to have converged. figure shows the estimated posterior distributions of the parameters obtained for different prior cases. posterior means and standard deviations are reported in table . in all the two cases the markov chain appeared to have converged after the burn-in period. the posterior means are well in agreement with the ml-estimate obtained from the complete data. table suggests that the estimation method is not very sensitive to the choice of prior information, as different choices result in parameter estimates that are in agreement with the ml-estimate. the acceptance rate for the sampler for b was around %. in order to assess model fit, the final size of the epidemic was chosen as the discrepancy measure. the posterior predictive distribution of final sizes obtained from the markov chain run did not show any evidence of lack of fit (posterior p-value ¼ . ). a good reference for posterior predictive distributions and posterior p-values is gelman, meng and stern ( ) . the algorithm described above was then applied to the real sars data set where the unobserved process b was imputed. it is assumed that there was initially one exposed individual and that the very first case was exposed for five days using the approximate mean incubation period according to leung et al. ( ) . this assumption implies that the outbreak started on february . it can be deduced from chau and yip ( a) that control interventions were introduced on or about days from the start of the epidemic implying that t * ¼ . from the data and the estimation of leung et al. ( ) , it follows that table parameter estimates for simulated data obtained while imputing b. for comparison, the ml-estimate for complete data is shown in the first row. the second and third row give posterior means using an informative and a non-informative prior distribution, respectively. posterior standard deviations are given in brackets. the true parameter values are . for b . for q and . for r . . ( . ) m e ¼ : ; s e ¼ : ; m þ ¼ : ; s þ ¼ ; m À ¼ : ; s À ¼ ; p ¼ : and n ¼ : million. an estimate for p was obtained as the total number of deaths divided by the sum of deaths and recoveries. values for r obtained from other studies (wallinga and tenius, ; mcbryde et al., ) together with eq. ( ) suggest that an informative value for b would be around . . gamma priors with parameters {( . , . ), ( . , . )} for fb; qg were therefore chosen to be informative. after discarding a burn-in period of , a sample of size taken every iterations of the chain was used to obtain posterior distributions and convergence monitored via autocorrelation functions. results obtained are summarized in table and in figure . results obtained with a vague prior on b and q were similar to the ones reported in table and are therefore not reported. results from table show that the estimated value of r is around . with a posterior standard deviation of . . this is larger than the value of . estimated by riley et al. ( ) but smaller than the value of . estimated by mcbryde et al. ( ) . the estimate is of the same magnitude as the value of . estimated by wallinga and tenius ( ) . the fact that a more precise value of r is obtained in this study than was previously obtained from other studies could possibly be explained by the following reasons. firstly, parametric forms of f ; g þ and g À already estimated by other scholars are used and secondly unlike in the case of riley et al. ( ) where only one time series fcðtÞg was used, this time series along with two other time series are used, thus improving the data availability. moreover, the use of the back-projection for rejection sampling purposes gives the model more detail as this method has been shown to successfully reconstruct sars epidemics. an estimate for the transmission parameter b was obtained as . with a posterior standard deviation of . . this estimate is consistent with a daily infectivity at the beginning of the epidemic of . obtained by mcbryde et al. ( ) . the model predicts that the effective reproduction number crosses the threshold value of one, seven days after control interventions were introduced. at the end of the epidemic, the effective reproduction number is as low as . suggesting that the epidemic was brought under control by the intervention measures. a posterior predictive distribution of final sizes shown in figure (b) does not indicate any evidence of lack of fit (p-value is . ). the fit of the model is also evident from figure (a) where the predicted number of cases is consistent with the observed cases. the bayes factor computed following the method of chib and jeliazkov ( ) was used to compare the proposed model with the model whereby f ; g þ and g À were assumed to follow a geometric distribution with the same mean as the gamma distributions used here. the geometric distribution is used here as in lekone and finkenstådt ( ) as a discrete approximation to the exponential distribution. the theoretical details of the scheme used to calculate the marginal likelihood of each model can be found in section . of chib and jeliazkov ( ) . a bayes factor of . in favour of the model with gamma distributions was obtained. a simple model that captures the form of distributions of epidemiological determinants has been introduced to estimate the basic reproduction number and to assess the effect of control interventions introduced during the course of the epidemic. mcmc methods were then used to carry out bayesian inference allowing for integration over latent variables. the performance of the inference method was demonstrated by applying it to simulated data and to data arising from an outbreak of sars in hong kong in . results obtained for the basic reproduction number from the sars data are slightly larger than those obtained by riley et al. ( ) and lipsitch et al. ( ) but in agreement with those obtained by wallinga and tenius ( ) . the model also predicts that the control measures introduced during the course of the epidemic were successful in bringing it under control. this was demonstrated by the effective reproduction number crossing the threshold value of one before the end of the epidemic. whilst it is appreciated that epidemic models for sars should incorporate the heterogeneity due to super-spread events, it would be difficult to infer from such models since they would require detailed data which is not readily available in practice. in the case that such data are available, modelling heterogeneity by incorporating it into the form of bðtÞ or by using a meta-population model as in riley et al. ( ) will be valuable. the model used here uses three time series of data that can read- ily be obtained by health practitioners in case of an outbreak and as such is easy to implement. however, better modelling ways of quantifying control interventions are desirable. the back-projection method was in this article used solely to construct an efficient proposal for the metropolis-hastings algorithm in order to impute the unobserved process fbðtÞg. this was motivated by the fact that the method reconstructed the sars epidemic quite well as was shown by chau and yip ( a, b) . the mcmc method can be modified to incorporate variability on the parameters of the gamma distributions used. these are assumed to be fixed in this paper, an assumption that might not be realistic as these are observed with error in real life situations. computation of the bayes factor can be quite difficult to compute especially in models with high number of parameters (chib and jeliazkov, ). however, this difficulty was not encountered in this article as only two parameters b and q were of interest. in the case that a variation of the model proposed here leads to a high dimensional parameter vector, then blocking methods as suggested by chib and jeliazkov ( ) can be used. the modelling approach proposed in this article is easy to implement and requires data that is not difficult to collect and hence can be applied to data sets arising from diseases with similar dynamics to sars. implementation of the methods described in this paper was done with a modern standard computer using the ox language of doornik ( ) . computation time was less than six hours for each of the markov chain runs. a method of non-parametric back-projection and its application to aids data dependent hiv incidences in back-projection of aids incidence data minimum size of the acquired immunodeficiency syndrome (aids) epidemic in the united states monitoring the severe acute respiratory syndrome epidemic and assessing effectiveness of interventions in hong kong special administrative region modelling the severe acute respiratory syndrome marginal likelihood from the metropolis-hastings output sars outbreaks in ontario, hong kong and singapore: the role of diagnosis and isolation as a control mechanism the basic reproductive number of ebola and the effects of public health measures: the cases of congo and uganda on the definition and the computation of the basic reproduction ratio r in models for infectious diseases in heterogeneous populations epidemiological determinants of spread of causal agent of severe acute respiratory syndrome in hong kong object-orientated matrix programming using ox version . . timberlake consultants limited posterior predictive assessment of model fitness via realized discrepancies statistical inference in a stochastic epidemic seir model with control intervention: ebola as a case study the epidemiology of severe acute respiratory syndrome in the hong kong epidemic: an analysis of all patients transmission dynamics and control of severe acute respiratory syndrome bayesian modelling of an epidemic of severe acute respiratory syndrome transmission dynamics of the aetiological agent of severe acute respiratory syndrome (sars) in hong kong: the impact of public health interventions different epidemic curves for severe acute respiratory syndrome reveal similar impacts of control measures acknowledgements the author would like to thank the university of warwick (warwick postgraduate fellowship), the united kingdom's national overseas research scheme (ors) and university of botswana for jointly funding this research. the manuscript benefited quite a lot from reports by two anonymous reviewers and an associate editor. the authors have declared no conflict of interest. key: cord- -l f gp authors: nan title: oral and poster manuscripts date: - - journal: influenza other respir viruses doi: . /j. - . . .x sha: doc_id: cord_uid: l f gp nan pandemic influenza h n (h n pdm) virus of swine-origin causes mild disease, but occasionally is associated with acute respiratory distress syndrome and death. , it is important to understand the pathogenesis of this new disease. previously we showed a comparable virus tropism and host innate immune responses between h n pdm and seasonal h n influenza virus in the human respiratory tract, however h n pdm virus differed from seasonal h n influenza virus in its ability to replicate in human conjunctiva, suggesting subtle differences in receptor-binding profile and highlighting the potential role of the conjunctiva as an additional route of infection. we now compare the tropism and host responses elicited by pandemic h n with that of related swine influenza viruses and a pandemic-swine reassortant virus in ex vivo and in vitro cultures of the human respiratory tract and conjunctiva. we have used recombinant virus to investigate the role of the hemagglutinin (ha) and neuraminidase (na) of h n pdm virus in its conjunctival tropism. these findings are relevant for understanding transmission and therapy. fragments of human conjunctiva, bronchi, and lung tissues were cut into - mm fragments within h of collection and infected with influenza a viruses at a titer of tcid ⁄ ml. viruses investigated included h n pdm (a ⁄ hk ⁄ ⁄ ), swine h n virus (a ⁄ swine ⁄ hk ⁄ ⁄ ), which shares a common derivation for seven genes with h n pdm, a natural swine reassortant h n (a ⁄ swine ⁄ hk ⁄ ⁄ ), which has acquired the na gene from h n pdm and other swine influenza h n viruses. reverse genetics derived recombinant viruses with ha and na gene segments of seasonal h n and pandemic h n swapped were also studied. lung fragments were cultured at °c in culture plates; conjunctival and bronchial biopsies were cultured in air-liquid interface at and °c respectively. tissue fragments were infected for h and incubated for , , and h post infection. infectious viral yield was assessed by titration in mdck cells. the infected tissues were fixed with formalin and analyzed by immunohistochemistry for influenza antigen. cytokines profiles induced by influenza virus infected respiratory epithelial cells in vitro were measured by quantitative rt-pcr and elisa. we found comparable replication in seasonal and pandemic h n viruses in human respiratory tract, while the swine influenza a ⁄ swine ⁄ hk ⁄ ⁄ (h n ) virus and a ⁄ swine ⁄ hk ⁄ ⁄ (h n ) virus failed to infect and replicate in human lung ex vivo culture, but it replicated productively in human bronchus ex vivo. interestingly, the swine reassortant influenza h n (a ⁄ swine ⁄ hk ⁄ ⁄ ) virus (with the na from h n pdm) infected and productivity replicated in lung ex vivo and in vitro. pandemic h n pdm virus, but not seasonal h n virus, was able to infect ex vivo cultures of human conjunctiva, suggesting subtle differences in receptor binding profile in h n pdm, seasonal viruses, and the swine related h n viruses. using reverse genetics derived recombinant viruses, we were able to demonstrate that the ha and na segments of h n pdm, but not the polymerase genes, were required for the conjunctival tropism of h n pdm ( figure ). in contrast with highly pathogenic influenza h n virus, which induced high cytokine and chemokine decretion, the related swine viruses, a ⁄ swine ⁄ hk ⁄ ⁄ (h n ), as well as the swine pandemic reassortant virus, a ⁄ swine ⁄ hk ⁄ ⁄ (h n ) we studied were similar to h n pdm and seasonal influenza viruses in their intrinsic capacity for cytokine dysregulation. collectively, our results suggest that pandemic h n pdm virus differs in modest but subtle ways from seasonal h n virus in its intrinsic virulence for humans, findings that are in accord with the epidemiology of the pandemic to date. the ha and na gene segments are key to the conjunctival tropism manifested by the h n pdm virus. the pandemic reassortant influenza h n (a ⁄ swine ⁄ hk ⁄ ⁄ ) virus isolated from swine with the na from h n pdm shares with h n pdm the capacity for productive replication in lung ex vivo and in vitro. these findings are relevant for understanding transmission and therapy. isolation of influenza viruses from specimens is traditionally performed in two classical systems: embryonated chicken eggs and mdck cell culture. nevertheless, several publications are dedicated to the theme of alternative cell culture systems, which may be used for influenza virus isolation and cultivation. [ ] [ ] [ ] this is in part because mdck cells are of animal origin, which means that they cannot be used as a proper model for estimating interactions between a human virus and a human cell culture as a host. a variety of human monolayer and suspension cell cultures have been tested on their capability to support influenza virus replication. among them, some support influenza a virus growth as well as mdck cells do, others support replication of a virus, but do not enable the formation of mature viral particles, whereas others show only a weak level of replication or are not permissive at all. caco- cells, for example, represent a good substitute for mdck cells, because it has been shown that the rate of viral isolation in caco- cells is as effective as in mdck, and sometimes is even better. the success of viral replication is determined not only by the cell culture type, but also by the virus itself. despite the accepted view that it is the type of receptor that defines the interaction between the virus and the host cell, there is evidence that it is not the only factor that predetermines the fate of the cell. the fate of the infected cell can also differ. a series of articles show that apoptosis is the most probable mechanism of cell killing by influenza viruses. , influenza a viruses of different subtypes induce apoptosis to a different extent (e.g. h viruses provoke more strong apoptotic response than h viruses do ). nevertheless, it has been demonstrated that caco- cells do not follow the apoptotic pathway and die through necrosis. the sjpl cell line also dies through necrotic pathway and not apoptosis. the aim of our work was to compare growth characteristics of different flu viruses (e.g. avian, swine, and human) in various human and animal cell cultures and to evaluate their influence on cell culture growth. the parameters measured in the study were as follows: cytopathic changes of cell cultures following virus infection, hemagglutinin production, np synthesis, the dose-dependent effect of infection on cell proliferation, and the ability of viruses to induce apoptosis. influenza viruses used included: highly pathogenic avian h n a ⁄ kurgan ⁄ ⁄ , low pathogenic avian h n a ⁄ gull ⁄ kostanai ⁄ ⁄ , swine h n a ⁄ swine ⁄ ⁄ , human h n v a ⁄ california ⁄ ⁄ , human h n v a ⁄ saint-petersburg ⁄ ⁄ , human h n a ⁄ brisbane ⁄ ⁄ , and human h n a ⁄ brisbane ⁄ ⁄ . the viruses were propagated in -days embryonated chicken eggs, the allantoic fluid was collected, the aliquots were made and stored at ) °c for further use. to evaluate tcid for each virus on all cell cultures, -well plates were used. the cells were seeded ae ml per well (concentration of - ae · cells ⁄ ml). the confluent -h old monolayer was used for viral inoculation. the cells were washed twice with serum-free medium, then ae ml of tenfold viral dilutions from viral aliquots were added and left for min for contact at °c. the cells were then washed to remove the non-attached particles, and the wells were filled with tpck-trypsin ( lg ⁄ ml)-containing medium without bovine fetal serum. the plates were observed daily for cytopathic effect, and the results were evaluated at h after infection for cytopathic effect and by reaction of hemagglutination with suspension of chicken erythrocytes ( ae %). infection of suspension cell cultures was done in centrifuge tubes. cells (concentration - · ) were inoculated with viral dilutions (moi = - ). after min of contact, cells were washed, resuspended in rpmi with trypsin and fetal serum, and seeded in -well plates ( ml in each well). the results were fixed after h, calculating the number of cells grown and estimating the rate of apoptosis by hoechst- staining. cells were grown in -well plates with seeding concentration · cells ⁄ ml. one millilitre of cell suspension was placed in each well, inoculated with viral dilution (moi = - ) and left for h. after, the cells were detached from plastic with versene and calculated in fuks-rosental camera to evaluate the number of cells. the monoclonal antibodies obtained in research institute of influenza towards viral nucleoprotein np were used following the standard protocol described in. for all viruses tested, mdck turned out to be more permissive than sp cell culture. avian viruses, independently of their pathogenicity, replicated efficiently on both animal cultures tested. human h n and h n viruses demonstrated weaker replication in sp cells. the most significant differences were seen for swine influenza and pandemic h n v viruses which replicated in mdck cells at the rates comparable with other viruses, but showed poorer growth in sp cell line (see table ). human cell lines displayed clear differences in their susceptibility to viruses of various origins. avian influenza viruses replicated in all cell lines except girardi heart, and the most intense replication rate was observed for ecv- , l- , and rd lines. a- and a- were poorly infected, as well as all suspension cell lines tested. seasonal human h n , as well as h n viruses, replicated in all cell cultures tested, but the rate of infectivity was rather low in practically all cultures tested with the exception of rd and t- g cell lines. strikingly, swine influenza virus and human pandemic h n v viruses didn't replicate well in any of human lines tested. a weak replication rate was observed in ecv- , rd, and t- g, but in general, human cell lines were the titers produced by swine and pandemic influenza viruses are shaded in grey. *low-pathogenic avian influenza virus; **highly-pathogenic avian influenza virus poorly susceptible to pandemic h n v. swine influenza virus differed because it infected weakly a- and girardi heart cell cultures, which was not the case for h n v viruses. our study has shown that all influenza viruses were able to induce apoptosis in the cell cultures tested. the degradation of chromatin found in the nucleus with hoechst- staining was seen before the first symptoms of cytopathic effect (cpe) in monolayer of cells. in cell cultures where the cpe was not visible, high doses of virus still induced apoptotic response. the process of apoptosis is rather well studied in mdck cells and some other cell types, so we've focused on three human monolayer cell cultures that are relatively poorly studied: a- , ecv- , and flech. these cell cultures are less susceptible to viral infection, and besides, it was interesting to find out whether the viruses that do not cause any cpe do infect these cultures. a- turned out to be most sensitive to apoptotic response, while flech turned out to demonstrate weak reaction. time needed for apoptosis induction by different flu viruses also varied. the earliest apoptosis was noted for h n and h n viruses and h n viruses induced apoptosis at about h postinfection. it is well-known that apoptosis can be induced only by a reproducing virus, and that uv-kills viruses that are not capable of it. we tested whether swine and pandemic h n v viruses (that do not show cpe in these cultures) do replicate in them and induce apoptosis with the help of monoclonal antibodies against viral np. the obtained data show that they indeed do replicate in these cell cultures, as we observed np fluorescence, and that they also induce apoptosis (see table ). we've shown earlier thus, we've tested the ability of swine and pandemic h n v viruses in this aspect. it was shown that these viruses were comparable with the effect seen for seasonal h n virus. moreover, swine influenza virus induced stronger apoptotic response in hemablastoid cell lines in comparison with pandemic h n v viruses, which also have a swine origin. we also checked the ability of flu viruses to influence monolayer cell cultures growth. the data clearly indicated that only ecv- endothelial line and t- g glioblastoma line displayed cell proliferation in response to low moi. apoptosis wasn't registered in these stimulated cultures, apparently because the moi was very low. all the other monolayer cultures didn't respond to low moi by stimulation of their proliferation. interaction between an influenza virus particle and a host cell can follow several scenarios. cpe seen in infected cells is accompanied with high rates of viral particles production and leads to cell death. the death itself may be through apoptotic or necrotic pathways. , also, infection process in low doses can stimulate cell proliferation -the effect seen for hemablastoid lines, histiocytes, peripheral blood cell lines, , and in glioblastoma and endothelial cell lines as it was described here. considering the origin of ecv line, these cells bear all the antigenic, biochemical, and physiological traits of umbilical cord and are actively used in pharmacological tests as well as glioblastoma cells; they also are of special interest for oncogenesis studies. table . replication, apoptosis induction, and np synthesis of influenza viruses in a- , ecv- and flech cell cultures. the numbers represent the log tcid ⁄ ae ml calculated by reed-muench method as described in. the ()) symbol means that no cpe could be observed in any dilution and no hemagglutination could be registered. the (+) symbol means that apoptosis was observed with hoechst- staining though the productive replication and production of progeny viruses in human cell lines was generally low, it is evident that viral infection does occur in these cells, even for swine and h n v viruses. it can be demonstrated by the presence of np de novo synthesis and by stimulation of virus-induced apoptosis. in fact, we observe a contradiction: avian influenza viruses actively reproduce in human cell lines, but we do not see their vast spreading in human population, while h n v viruses that hardly replicate in all human cultures tested have caused the latest pandemic. influenza viruses continue to cause problems globally in humans and their livestock, particularly poultry and pigs, as a consequence of antigenic drift and shift, resulting frequently and unpredictably in novel mutant and reassortant strains, some of which acquire the ability to cross species barriers and become pathogenic in their new hosts. long-term surveillance of influenza in migratory waterfowl in north america and europe have established the importance of anseriformes (waterfowl) and charadriiformes (gull and shorebird) in the perpetuation of all known subtypes of influenza a viruses. the available evidence suggests that each of the hemagglutinin (ha) and nine neuraminidase (na) subtype combinations exist in harmony with their natural hosts, cause no overt disease, and are shed predominantly in the feces. , in this study we determined the subtypes and prevalence of low-pathogenic influenza a viruses present on the territory of kazakhstan in - and further analysed the ha and na genes of these isolates in order to obtain a more detailed knowledge about the genetic variation of influenza a virus in their natural hosts. (institute for biological safety problems, gvardeiskiy, zhambyl oblast, kazakhstan)). samples that were identified as influenza a virus positive by matrix rrt-pcr were thawed, mixed with an equal volume of phosphate buffered saline containing antibiotics (penicillin u ⁄ ml, streptomycin mg ⁄ ml, and gentamicin lg ⁄ ml), incubated for minutes at room temperature, and centrifuged at g for minutes. the supernatant ( ae ml ⁄ egg) was inoculated into the allantoic cavity of four -day old embryonated hens' eggs as described in european union council directive ⁄ ⁄ eec. embryonic death within the first hour of incubation was considered as non-specific, and these eggs were discarded. after incubation at °c for days the allantoic fluid was harvested and tested by haemagglutination (ha) assay as describe in european union council directive ⁄ ⁄ eec. in the cases where no influenza a virus was detected on the initial virus isolation attempt, the allantoic fluid was passaged twice in embryonated hens eggs. the number of virus passages in embryonated eggs was limited to the maximum two to limit laboratory manipulation. a sample was considered negative when the second passage ha test was negative. the subtypes of the virus isolates were determined by conventional haemagglutination inhibition (hi) test and neuraminidase inhibition (ni) test, as describe in european union council directive ⁄ ⁄ eec. rna extraction and pcr with specific primers rna was extracted from infective allantoic fluid using rneasy mini kit (qiagene, gmbh, germany) according to the manufacturer's instructions. the rna was converted to full-length cdna using reverse transcriptase. the rt mix comprised ae ll of dmpc water, ll of · first strand buffer (invitrogen), ae ll of mm dntp mix (amersham biosciences), ll of mm uni primer, u of rnaguard (amersham biosciences), u of mmlv reverse transcriptase (invitrogen) and ll rna solution in total volume of ll. the reactions were incubated at °c for minutes followed by inactivation of the enzyme at °c for min. pcr amplification with ha and na gene specific primers was performed to amplify the product containing the full length ns gene. twenty-five microliter pcr-mix contained · platinum taq buffer (invitrogen), lm dntp, ae mm mgcl , nm each of fw primer and rw primer, u platinum taq dna polymerase (invitrogen) and ll cdna. reactions were placed in a thermal cycler at °c for min, then cycled times between °c seconds, annealing at °c for seconds, and elongation at °c for seconds and were finally kept at °c until later use. sequences of the purified pcr products were determined using gene specific primers and bigdye terminator version ae chemistry (applied biosystems, foster city, ca), according to the manufacturer's instructions. reactions were run on a abi tm dna analyzer (applied biosystems). sequencing was performed at least twice in each direction. after sequencing, assembly of sequences, removal of low quality sequence data, nucleotide sequence translation into protein sequence, additional multiple sequence alignments, and processing were performed with the bioedit software version ae ae ae with an engine based on the custal w algorithm. the phylogenetic analysis, based on complete gene nucleotide sequences were conducted using molecular evolutionary genetics analysis (mega, version ae ) software using neighbor joining tree inference analysis with the tamura-nei c-model, with bootstrap replications to assign confidence levels to branches. [ ] [ ] [ ] [ ] ha and na sequences obtained from genbank the ha and na gene was analyzed both with selected number of influenza isolates and in comparison with virus genes obtained from genbank were used in phylogenetic studies [ ] . the nucleotide sequence data obtained in this study has been submitted to the genbank database and is available under accession numbers fj , fj ae , fj , fj , gu -gu for ha and fj , fj ae , fj , fj , gu -gu for na. avian influenza prevalence in our study h , h , and h influenza a virus subtypes were found to circulate at the same time, in the same geographic region in the kazakhstan. this finding most likely indicates the existence of a large reservoir of different influenza a viruses in kazakhstan. we analyzed the ha and na gene sequences of the eight influenza a viruses isolated in kazakhstan together with selected number of isolates, reported between year to , and previously published in the genbank. phylogenetic analysis of the h ha gene showed that all viruses separated into the american and eurasian lineages ( figure ). an evolutionary tree suggests that north american isolates have diverged extensively from those circulating in other parts of the world. geographic barriers which determine flyway outlay may prevent the gene pools from extensive mixing. the lack of correlation between date of isolation and evolutionary distance suggests that different h ha genes co circulate in a fashion similar to avian h ha genes and influenza c genes, implying the absence of selective pressure by antibody that would give a significant advantage to antigenic variants. analysis of phylogenetic relationships among the ha ha genes reported in this study clearly shows that viruses belong to the western pacific flyway, one of the major migratory flyways in this region that have subsequently spread throughout eurasia. these findings provide further evidence of the dynamic influenza virus gene pool in this region. along the western pacific migratory flyway, the influenza virus gene pool in the domestic waterfowl of southern china has 'mixed' longitudinally with viruses isolated from japan, mongolia, and siberia. however, it appears that there has also been 'mixing' latitudinally through overlapping migratory flyways, thereby facilitating interaction between the influenza virus gene pool in domestic waterfowl in the eastern and western extremities of the eurasian continent. this helps to explain the latitudinal spread of the qinghai-like (clade ae ) h n virus in the last years, while h n outbreaks in korea and japan may represent the longitudinally transmitting pathway. ha of subtype h so far has been found exclusively in shorebirds, such as gulls, and in a pilot whale (potentially a spillover from shorebirds), but not in other avian species that are natural hosts of influenza a virus, such as ducks and geese; therefore the study of the evolution of these viruses is very interesting. phylogenetic analysis h ha gene revealed three significantly different evolutionary lines: an american line, a european line, and a line comprising the isolates from america and eurasia. further we analyzed na genes of influenza viruses (figure ) . the na gene is important both because of its functional role in promoting the dissemination of the virus during infection, and because, like ha, it is a principal target of the immune system. it was shown that phylogeny of na genes of influenza have the same properties as hemagglutinin. na genes of kazakhstanian viruses belong to eurasian lineage of virus evolution. obtained data are important for surveillance and diagnostics because some of the lpai viruses examined in this study can infect and be shed by chickens and turkeys and may have epidemiology potential during further recombination with other influenza viruses. influenza virus is divided into different subtypes based on hemagglutinin (ha) and neuraminidase (na) on the virus surface. within each subtype, ha continues to mutate and produce immunologically distinct strains, as antigenic drift. the continuous mutation of influenza virus (iv) is important for annual epidemics and occasional pandemics of disease in humans. antigenic drift requires vaccines to be updated to correspond with the dominant epidemic strains. in humans, ivs show both antigenic drift frequently. in contrast, ivs from birds are in evolutionary stasis, and they show little amino acid changes. , the reason is that ivs in bird intestine are not subjected to strong immune selection. hemagglutinin (ha) gene of influenza a virus encodes the major surface antigen, which is the target for the protective neutralizing antibody response that is generated by infection or vaccination. in humans, influenza a viruses show antigenic drift with amino acid changes in the globular head of the ha so as to evade herd immunity of the population. on the contrary, avian influenza a viruses show evolutionary stasis in wild birds. h aivs have occurred frequently in chicken farms in the world. although vaccination is not permitted, h n aivs have circulated in taiwan for a time. the seroprevalence in chicken flocks reaches about % in the field. h n aivs invades internal organs, such as kidney and lung. thus, viruses in chicken flocks are pressured into antibody selection. here, we report that h n aivs in the field have showed evolutional changes instead of evolutional stasis. in response to requests from poultry farmers for diagnostic investigations of illness in poultry flocks, the authors did necropsy at the pen-site. after careful examination, tracheae were taken and kept in cold for virus isolation in the laboratory. for avian influenza virus isolation, trachea was homogenized : in tpb with antibiotics. the homogenate was frozen and thawed three times and then centrifuged at g for minutes. the supernatant was passed through a ae lm filter. the homogenate was examined for the presence of virus by inoculation into five -to -day-old specific-pathogen-free (spf) chicken eggs for two passages. thirteen h n aivs were isolated in this laboratory during and from different parts of taiwan. besides the viruses isolated in this laboratory, the ha sequences of chicken h n aivs were from the genbank. the accession numbers of hemagglutinin of aiv reference strains included in this study were as the following: g ⁄ , dq ; g ⁄ , dq ; ⁄ , dq ; na ⁄ , dq ; ⁄ , dq ; ⁄ , dq ; ns ⁄ , dq ; sp ⁄ , dq ; ⁄ , dq ; ⁄ , dq ; ⁄ , dq ; ⁄ , dq ; ⁄ , dq ; ⁄ , dq ; pf ⁄ , dq ; pf ⁄ , dq ; pf ⁄ , dq ; a ⁄ , dq ; ⁄ , dq ; ⁄ , dq ; ⁄ , dq ; ⁄ , dq ; ⁄ , dq ; ch ⁄ , dq ; ⁄ , dq ; a ⁄ , dq and ⁄ , dq . the viruses isolated were propagated in the allantoic cavities of -day-old embryonated spf eggs for hour. the virus rna was extracted using qiaamp viral rna miniprep kit (qiagen) . six-week-old balb ⁄ c mice were injected emulsion intraperitoneally with lg of purified and concentrated a ⁄ chicken ⁄ taiwan ⁄ v ⁄ (h n ) virion with complete freund's adjuvant. every two weeks, the mice were boosted supplementary five times with lg of virion in incomplete freund's adjuvant. when the mice were boosted, blood was collected from tail vein and tested by the western blot assay to check the antibody titers. the mice were then injected intraperitoneally with lg of virion at week . five days after the last injection, the splenocytes in the mice were fused with myeloma cells (sp ⁄ -ag ). one week before fusion, the myeloma cell line was expended in dmem medium (hyclone laboratories, logan, ut) with % fetal bovine serum at °c to ensure they were in the exponential growth phase. the spleen cells from immunized mice were washed, harvested, and mixed with the previously prepared myeloma cells and fused by gradually adding % polyethylene glycol- . the resulting pellet was plated into well tissue culture plates. only the fused cells grew in medium with hypoxanthine-aminopterin-thymidine (hat). with fresh medium replacement over weeks, the hybridomas were ready for screening. hightiter monoclonal antibody (mab) preparations were obtained from the ascetic fluid of mice injected with the selected hybridoma clones. the antibody from mouse ascetic fluids was purified by precipitation with ammonium sulfate, then aliquoted and frozen at ) °c, avoiding repeated freezing and thawing. eventually, six mabs were obtained and named ch -d , eb -b , eb -e , eb -f , ff -f , and ff -f , respectively. the hi test was performed following a standard method. all the viruses were diluted twofold and reacted with % chicken erythrocytes in the v-bottomed microtiter plate by the hemagglutination test. after agglutination, four hemagglutinating units of a ⁄ chicken ⁄ taiwan ⁄ v ⁄ (h n ) and ascetic fluids from the immunized mice of the six mabs were prepared for hi test. hi titers of or more were regarded as positive. the cases submitted for diagnosis from chicken farms had respiratory signs, increase in mortality, or drop in egg production (e.g. egg production dropped from % to %). the extent of drop in egg production depended on the chicken ages. for example, the age of case was weeks, a stage of increasing egg production. however, after h n aiv infection, the egg production decreased % instead of increasing and then stayed at % for a week. the infected chickens showed signs of decreasing activity, anorexia from g per bird to g per bird, and respiratory signs. case showed infection in the second floor first and then transmitted to third and fourth floor, indicating that the virus transmitted by air or human movement. however, most cases showed air borne transmission from one flock to another in spite of enforcing restrictions of persons entering the poultry pens and changing clothes and booths. in most cases, males' mortality was higher than that of female pen mates. by comparing the sequences of ha of those h n viruses, we found that amino acid changes in ha were higher than those in ha , showing that antigenic changes on the globular head of ha molecule rather than randomly on the whole ha protein, indicating that h n viruses in taiwan had been selected in the presence of antibody pressure. the aa residues and changes that showed yearly trends were the followings: a- s, i s, v i, n s, e k, l m, e d, q k, a v, or t, s n, s r, k n, y d, n t, s i, g d, l v, i v, g e, t n, g s, a v, k e, d n, i m, and m i. however, their significance on antigenic variation was previously unknown. by hemagglutinination inhibition (hi) assays, except mab ch -d , all other monoclonal antibodies elicited from v ⁄ showed different hi titers with the different h n viruses (table ). however, those mabs showed negative hi to and , the early h n strains. this indicated that the epitopes recognized by those mabs were undergoing antigenic drift. introduction aquatic birds are recognized as the natural reservoirs of the influenza a virus as all known subtypes (h -h , n -n ) have been found in them. phylogenetic analyses of influenza viruses found in other animals revealed that all were directly or indirectly derived from viruses resident in aquatic birds. however, the prevalence, movement, and evolutionary dynamics of influenza viruses in these avian hosts have not been well defined. southern china was hypothesized to be an 'epicenter' for the generation of human pandemic influenza viruses as all major influenza pandemic viruses in the th century emerged from this region. the ecological background that facilitates the occurrence of these pandemic influenza strains has not been fully explored. in the past two decades, four lineages, belonging to h n , h n , and h n viruses, have become established and long-term endemic in different types of poultry in this region. [ ] [ ] [ ] some of these viruses were disseminated to many countries in eurasia and africa and have continued to cause sporadic human infection, posing a persistent pandemic threat to the world. in the mean time, the endemic influenza lineages have undergone extensive genetic reassortment events giving rise to many variants, dramatically increasing the genetic diversity of the influenza virus in this region. questions remain as to how and where these viruses emerged, and what were the sources of the gene segments incorporated within the novel reassortant variants of the h n , h n , and h n virus lineages. to address these questions, surveillance of influenza in migratory and domestic (sentinel) ducks has been conducted since at poyang lake, the biggest fresh-water lake and the major migratory bird aggregation site in southern china. the aim of this study is to identify the prevalence, seasonality, and movement of virus between migratory and domestic ducks. migratory ducks were captured during over-wintering, from november to march. cloacal swabs and blood samples were collected from each individual bird. all birds were released after sampling. to observe the interaction between migratory ducks and domestic birds, we also sampled domestic ducks from two duck farms (designated as sentinel ducks) surrounded by rice fields and inaccessible to other types of poultry, but accessible to migratory birds. that is, the sentinel ducks share the same water body with migratory ducks and have the chance to spread viruses to each other. for sentinel ducks, sampling was conducted fortnightly, all year-round, on the two farms from august onwards. cloacal swabs and fresh fecal droppings were taken. about birds were randomly sampled fortnightly from these farmed ducks. all swabs were soaked in vials containing ae ml transport medium with antibiotics and kept on ice-packs during sampling and immediately stored in ) °c freezers for further use. blood samples from migratory ducks were treated according to methods previously described. serological survey and virus subtyping in migratory and sentinel ducks used hemagglutination inhibition (hi) and neuraminidase inhibition (ni) tests as previously described. for isolates that were not identified by reference antisera, subtypes were determined by rt-pcr using subtype specific ha and na diagnostic primers. prevalence and seasonal patterns of influenza virus in migratory and sentinel ducks during during - a total of cloacal swabs from migratory ducks and cloacal or fecal swabs from sentinel ducks were collected at poyang lake. from these specimens, influenza isolates were obtained from migra- tory ducks and from sentinel ducks; isolation rates of ae % and ae %, respectively (table ) . it was noted in sentinel ducks that virus occurrence formed a seasonal peak from november to february, which completely overlapped the over-wintering months of migratory ducks. this suggests that virus movement or transmission between migratory and sentinel ducks occurred during this period at poyang lake. thirty positive samples (hi titer ‡ ) were identified from blood samples collected during november and december in . among these, samples were positive to h , were positive to h , were positive to h , and were positive to h . one serum sample was positive to both h and h , which suggested co-infection of influenza virus in migratory ducks might occur in natural conditions. poyang lake, which is located in the northeastern part of jiangxi province, is the largest freshwater lake in china and is part of the eastern asia-australia migration route. every year, hundreds of thousands of migratory ducks congregate at poyang lake during the migration season. recent farming practice involves raising domestic waterfowl in dense populations in the poyang lake region. farmraised domestic waterfowl are allowed to feed in and share the same water body with migratory birds, thereby facilitating direct interactions between domestic waterfowl and freeranging migratory birds. this makes poyang lake an ideal site to observe the dynamics of influenza virus interactions between migratory and sentinel ducks in southern china. in our longitudinal surveillance during [ ] [ ] [ ] [ ] [ ] [ ] , the overall virus isolation rate from migratory ducks was less than %, which suggests a low prevalence of viral infection during the birds' southern migration. similar results have been observed in taiwan, which is also an important stopover site for migratory birds along the eastern asia-australia migration route during years of surveillance. the overlap in seasonal patterns of virus infection between migratory and sentinel ducks found in our study suggests that virus movement or transmission between migratory and sentinel ducks occurred during the period of time migratory birds were at poyang lake. the ha subtypes harbored in migratory and sentinel ducks were similar in our study. for migratory ducks, h , h , h were the predominant subtypes, while h , h , and h were the major subtypes in sentinel ducks. hpai h n was only detected from migratory ducks in early on two sampling occasions. from phylogenetic analyses the h n viruses isolated from migratory ducks were closely related to the viruses endemic in domestic poultry in southern china. therefore, it appears that h n viruses endemic in domestic poultry could be transmitted to migratory ducks via close contact in southern china. only lp h viruses were detected from sentinel ducks at poyang lake during this period. whether h n virus infection was absent from sentinel ducks at poyang lake needs further investigation. serological surveys provided further evidence for the prevalence of aiv in migratory ducks at poyang lake. the serological results in did not match well with the epidemiological results during [ ] [ ] [ ] [ ] [ ] [ ] , which suggests that influenza virus infection in migratory birds could be influenced by multiple factors, such as host immune status, population size, spatial and temporal variations, and migration routes. southern china has the biggest domestic duck population in the world. our study demonstrates that dynamic interactions between migratory ducks and sentinel ducks occurred frequently throughout the surveillance period. thus, sentinel ducks could be treated as intermediate hosts between the ''real gene pool'' from migratory ducks and domestic poultry in the whole influenza virus ecosystem. a sentinel duck sampling system may be a feasible method to represent the viruses in the natural gene pool and a baseline for virus or gene interactions between migratory and domestic ducks. further investigations and surveillance are required to better understand the role of the domestic duck population in facilitating virus interactions and the generation of genetic diversity. two distinct lineages of h n influenza viruses represented by a ⁄ chicken ⁄ beijing ⁄ ⁄ (ck ⁄ bei-like) and a ⁄ quail ⁄ hong kong ⁄ g ⁄ (g -like) have become established and endemic in poultry in southern china. these established h n lineages continue evolving to generate many different reassortant variants (or genotypes) , and are causing sporadic cases of human infection. , studies of h n viruses isolated from pigs in hong kong and shandong province have also raised the possibility of reassortment with human-like viruses from pigs. , in addition, h n viruses isolated beyond the late s had preferential binding with a- , -neuacgal human-like receptors. these observations suggest that the h n influenza viruses still have pandemic potential. unlike highly pathogenic h n influenza viruses that have been rarely detected in the live-poultry markets in hong kong since , h n viruses are still frequently isolated in our surveillance program. therefore, we try to understand the continuing evolution of h n viruses through genetic characterization and phylogenetic analyses of the viruses isolated in hong kong live-poultry markets from to . a total of terrestrial poultry were sampled at different live-poultry markets in the hong kong sar between january and december . of those samples, were from chickens and the others were from minor poultry species including chukar, pheasant, guinea fowl, silky chicken, and pigeon. fecal droppings, cloacal and tracheal swabs, drinking water, and environmental samples from cages were collected into transport medium. viruses were isolated in -to -day old embryonated eggs as described previously. virus isolates from positive sampling occasions were selected for sequence analysis. rna extraction, cdna synthesis, and pcr were carried out as described previously. dna sequencing was performed using bigdye terminator v ae cycle sequencing kit on an abi dna analyzer (applied biosystems) following manufacturer's instructions. all sequences were assembled and edited with lasergene ae (dnastar, madison, wi) software. sequence alignment and residue analysis were performed with the bioedit sequence alignment editor, version ae . all eight gene segments of sequenced viruses were characterized and analyzed phylogenetically together with virus sequence data available in public databases. maximum-likelihood trees were constructed using garli ae . estimates of the phylogenies were calculated by performing neighbor-joining bootstrap replicates using paup* ae . systematic surveillance of live-poultry in hong kong from to resulted in h n isolates from samples (overall isolation rate, ae %) ( table ). there were strains isolated from chicken samples (isolation rate, ae %). of these viruses, four were isolated from tracheal swabs (isolation rate, ae %), while isolates were isolated from cloacal or fecal swabs (isolation rate, ae %). an additional isolates were collected from drinking water samples (isolation rate, ae %). there were strains of h n viruses isolated from minor poultry samples (isolation rate, ae %) ( table ) . of these viruses, only one was isolated from tracheal swabs (isolation rate, ae %), whereas strains of viruses were isolated from cloacal or fecal swabs (isolation rate, ae %). the isolation rate in drinking water in minor poultry was again higher when compared with other sampling methods with strains isolated from drinking water samples (isolation rate, %). taken together, these findings suggest that the h n viruses mainly replicated in the intestinal tract of chickens and minor poultry species. also, the high isolation rate in drinking water samples could be a sensitive indicator for monitoring the prevalence of h n viruses in the field. to better understand the evolutionary pathway of h n viruses in southern china, representative viruses, isolated from hong kong live-poultry markets from to , were sequenced and genetically characterized. phylogenetic analysis of the h ha gene revealed that ck ⁄ bei-like viruses were predominant and one chicken isolate had a g -like ha gene ( figure ). this is the first time the g like h ha gene has been detected in chickens from livepoultry markets in hong kong. the ck ⁄ bei-like lineage is further divided into two subgroups as previously described. subgroup is represented by qa ⁄ st ⁄ ⁄ and subgroup is represented by dk ⁄ hk ⁄ y ⁄ . all h n viruses in this study belonged to subgroup of the ck ⁄ bei-like lineage except for the virus with the g -like ha gene. phylogenetic analysis of the na gene also showed a similar evolutionary pattern to the ha gene with all viruses clustered within the ck ⁄ bei-like lineage. these results revealed that ck ⁄ bei-like viruses are predominant in both chickens and minor poultry. all of the pb , pa, np, ns and m genes clustered with those of h n lineage viruses previously prevailing in ter- restrial poultry in southern china. phylogenetic analysis of the pb gene revealed three different lineages; g -like (n = ), ck ⁄ sh ⁄ f ⁄ -like (n = ), and unknown avian (n = ). the sh ⁄ f ⁄ -like lineage (or f ⁄ -like) was previously reported in eastern china and was used previously for vaccine production in an intensive vaccination program. this pb gene lineage was also distinguishable from the ck ⁄ bei-like lineage and its presence in the viral genome may be due to reassortment between the vaccine strain and field isolates, followed by selective establishment in terrestrial poultry. gene constellation analyses of the viruses revealed six genotypes. thirty-four of the viruses analyzed belonged to two genotypes, b and b , which were also the prevailing reassortants found in other provinces in southern china since . the remaining sixteen viruses belonged to four novel genotypes that have not been identified before in this region. characterization of h n influenza viruses isolated from live poultry in hong kong markets from a year surveillance program revealed that ck ⁄ bei-like viruses were predominant in southern china and were continuing to evolve. two recognized and four novel genotypes were identified in this study. one characterized virus, ck ⁄ hk ⁄ nt ⁄ , had a g like ha gene (the first time this has been detected in hong kong poultry markets) that showed a close relationship with two human h n strains isolated in . g -like viruses were usually detected and caused outbreaks in chickens of middle eastern and european countries, [ ] [ ] [ ] and minor poultry, mainly quail, in southern china. whether the g -like virus was transmitted from china to middle eastern and european countries, as the highly pathogenic h n virus did in the last five years, or vice versa, is still unknown. since the ck ⁄ hk ⁄ nt ⁄ strain clustered with other g -like strains isolated previously in minor poultry in southern china, the g -like viruses in chicken may be due to interspecies transmission from minor poultry species. genetic studies demonstrated that reassortants with genotypes b and b persistently occurred in either chickens or other minor poultry species from to . other genotypes that were prevalent in southern china might be being gradually replaced and four novel genotypes were identified in this study. these novel genotypes were generated through reassortment of viruses with different lineages. a newly emerged f ⁄ -like lineage originating from eastern china is responsible for generation of some of the novel genotypes found in this study. the ck ⁄ bei-like lineage is gradually being replaced by f ⁄ -like lineages which are becoming dominant in northern and eastern china. , animal experiments have also demonstrated that f ⁄ -like viruses are more effective in replication and transmission in chickens compared with ck ⁄ bei-like viruses. since the f ⁄ -like lineage of the pb gene has been introduced into southern china, this newly emerged lineage may have a higher tendency to replace the rnp genes in the circulating ck ⁄ bei-like viruses and subsequently become the endemic virus in terrestrial poultry. in vietnam, the modelling of the pandemic h n progression estimates that ( - ) pigs might be exposed to the virus on the basis of cases among swine owners ( - ). a poor level of biosecurity, high animal densities, and a mix of species could increase the risk of influenza virus flow, persistence, and emergence on swine and poultry farms. this study was set up in the red river delta, where a third of the national pig husbandry is produced. the aims are to give preliminary information of the epidemiological state of swine influenza and in order to further assess the risk of infection of swiv, through cross-species transmissions from poultry to pigs. this paper will present the preliminary results on swiv and the risk factors of pig seropositivity in vietnam. a cross-sectional study was conducted in two provinces of the red river delta in april . pig farms were randomly selected from nine communes representative of at risk area of avian h n . in each farm, pig and poultry were sampled and collected to virological and serological analyses. interviews were conducted in all farms by trained interviewees. questionnaires included closed and open questions on ª blackwell publishing ltd, influenza and other respiratory viruses, (suppl. ), - livestock husbandry ⁄ management and household characteristics, such as herd size and structure, health history and vaccination, pig housing, watering and feeding system, reproduction, purchasing of animals, biosecurity measures, pig contact with poultry, and environmental factors. the virological detection assay was performed on pools of nasal swab specimens from pigs. we investigated whether real-time rt-pcr assay could detect gene m on pools of nasal swab specimens before attempting virus isolation from individual nasal swab specimens. the poultry and pig sera were tested against influenza type a with an enzyme-like immunosorbant assay (elisa) competition test idvetª. this commercial kit is designed to specifically detect antibodies directed against the np protein antigen of influenza type a viruses. the positive serum samples were examined in hemagglutination inhibition (hi) to determine antibody titers and subtypes. the hi test was tailored for h , h , and h subtypes in pigs and h and h subtypes in poultry. seroneutralization tests by pseudo particles were used to test the presence of antibodies directed against h subtype. we analysed the data for relationships between influenza a serological status (the outcome variable) and possible risk factors using r version ae ae (r development core team). the statistical unit was the individual. initially, the quantitative variables were encoded into categorical variables according to the quartiles or median. descriptive statistics (e.g., means or medians, proportions, standard deviations) were calculated for all herd-level and commune level predictors to assist in the subsequent modeling process. we also performed the independence test among all variables to determine if variables were dependant. then, univariate analysis of potential risk factors for the pigs being positive for swiv and estimation of odds ratios were performed using generalised linear mixed models with binary outcome and logit link function for each herd-level and commune-level variable to determine which variables were individually associated with influenza a seropositivity at a significance level of p < ae . herd and commune of residence were included as a random effect to account for the correlation of observations at the herd level. the third stage of the analyses included the four herdlevel variables found to be significantly (p < ae ) associated with influenza a seropositivity. an automatic process using all possible associations between the selected variables was computed into a mixed logistic regression models, with random effects. when two variables were collinear, as determined before, only one variable was likely to enter the multivariable model, and therefore, the selection of which collinear variable to enter the model was guided by biological plausibility and statistical significance. all of the pools of nasal swabs were rt-pcr negative. the maximal possible prevalence considering perfect diagnostic tests would be of ae % at a confidence level of %, in an infinite population within these regions (win-episcope ae ). six hundred-and-nine pig sera were tested in nonvaccinating farms. the herd seroprevalence of swine influenza in the commune previously infected by the avian h n in the red river delta raised by ae % [ ae ; ae ] in april . but among seropositive farms, only four had at least two seropositive pigs. the within-herd seroprevalence is very low, and no seropositivity was detected in the majority of farms. estimates had large confidence intervals due to small sample sizes. the individual seroprevalence raised ae % [ ae ; ae ]. the subtyping of seropositive sera is still in process. descriptive statistical analyses on five major risk factors of swiv: farm size, breeding vs. fattening, purchasing, percentage of family income, and poultry production, were conducted. based on this analysis, three types of farming systems were identified and included in mixed models ( table ) . percentage of family income by pig production and poultry production were not differentiating factors for this typology. whereas types and seem to be specialized in fattening, the type produces and might sell piglets on the farm site. the exploration of the different variance components indicated that the random effect variances were mainly associated with the herd, while the commune did not seem to have any effect. therefore we included in all models only the herd as a random effect. the random effect term for herd was modelled, assuming a normal distribution with a table . typology of farming system type : large fattening farms largest scale production, with more than pigs per year specialized in fattening, and purchase more than pigs per year type : small fattening farms small scale of production, with less than pigs per year specialized in fattening, and purchase less than pigs per year type : medium breeding-fattening farms medium scale of production, with less than pigs per year breeding and fattening piglets, with rare purchase common variance [$n( ,r herd)]. the univariate analyses were conducted on variables and typology variables, with herd as random effect. some coefficient or confidence intervals were inconsistent because of small effectives, especially for the percentage of self-product culture or the pig freegrazing because of the lack of positive results in the dataset. the only one significant (p value < ae ) parameter was the percentage of pig sales in the familial annual income. surprisingly, common risk factors of swine influenza infection, such as farm size, animal movements, and sanitary parameters got low odds ratio individually (without being significant); the typology provides the hypothesis of complex interactions effects that increase the risk of infection. as shown in table , the farming system type got a higher seroprevalence of ae % [ ae - ae ] and a higher risk indicator, with or = ae (p-value = ae ) in comparison with type . this finding was not significant. in the multivariate mixed model, the percentage of familial income provided by pig production was the only one significant variable, with or = ae [ ae - ae ]. the focus on diseased animals in the winter-time is usually required in order to increase the likelihood to isolate the virus, although the isolation rate on healthy or clinical samples never exceed %. the season and the lack of disease reports might explain the difficulties to detect influenza viruses. additionally, the pooling method tends to decrease the isolation rate because of a dilution effect, potential presence of pcr assay inhibitors, or uneven distribution of virus in the sample. our seroprevalence results must be confirmed and the subtypes identified, especially because we found only one positive animal in a few farms that could be attributed to false positive results of the elisa test (performances are not known). these preliminary results are in favor of a virus circulation at low level in the spring, but must be completed by further surveys in the winter and before the new year (têt celebration) when pig production, trade, and movement increase at their maximum. no clear prior information on the expected prevalence of swine influenza in vietnam, tests sensitivity, and speci-ficity could be obtained from literature or reliable sources. bayesian methods will be carried out in the future in order to compute prevalence and ⁄ or to estimate the probabilities of freedom. the risk factors analysis was limited by the lack of positive results. further studies are necessary to identify the at-risk season and type of farming systems at risk of swine influenza infection. however, this investigation of risk factors leads to the hypothesis that medium size breeding-fattening farms had a higher risk than large or small size fattening farms. further investigation are needed to precise this typology. the risk of swiv infection increases with a combination of three major factors. poultry production does not seem to play any role on swine infection. the generalized linear mixed model afforded to take into account all the non investigated parameters at the herd level. although we investigated the most common risk factors of swine influenza infection covering different kind of fields, the herd random effect might explain risk variations. mixed models have become a frequently used tool in epidemiology. due to software limitations, random effects are often assumed to be normally distributed. since random effects are not observed, the accuracy of this assumption is difficult to check. further studies, such as case-control or cohort studies could help to identify more precisely risk factors of swine influenza seropositivity, as these study designs are more adapted than cross-sectional studies. the concept that swine are a mixing-vessel for the reassortment of influenza viruses and for the emergence of pandemic influenza viruses has been re-enforced by the emergence of the recent pandemic. the pandemic h n virus of (h n pdm) is believed to have emerged through the reassortment of north american triple reassortant and eurasian avian-like swine influenza viruses. since the immediate precursor of this pandemic virus has not yet been identified, it is not possible to be definite whether the reassortment leading to the pandemic occurred in swine, but swine influenza viruses are the nearest known ancestors of each gene segment of h n pdm. , the mechanisms of pandemic emergence are not clear. it is believed that the pandemics of and arose through reassortment of the pre-existing human seasonal influenza virus with avian influenza viruses, and swine have been proposed to be a possible intermediate host where such reassortment between human and avian viruses may take place. the pandemic was the first to arise for over years and the first to occur after the understanding that pandemics arise from animal influenza viruses. systematic studies of influenza virus ecology and evolution in swine are, therefore, important in order to understand the dynamics of pandemic emergence. furthermore, since swine are the likely host within which h n pdm virus originated, it was predicted that this virus would readily infect swine and may reassort with endemic swine influenza viruses. these predictions have now been confirmed with reports of h n pdm being detected in pigs in many countries and reassortment with endemic swine influenza virus being confirmed. while h n pdm has been genetically and antigenically stable in humans, reassortment between h n pdm, which is well adapted to transmission in humans, and other avian or swine viruses may lead to the origin of novel viruses posing a threat to public health. in addition to endemic swine virus lineages, avian influenza viruses such as h n and highly pathogenic avian influenza (hpai) h n have also been occasionally identified in pigs in parts of asia. , it has been shown that h n pdm readily reassorts with h n to generate viable progeny in vitro. it is therefore essential to monitor the ecology, evolution, and biological characteristics of swine influenza viruses so that their continued evolution and zoonotic and pandemic potential can be monitored. there is however, a paucity of surveillance data on swine influenza viruses worldwide. this is in part related to the negative commercial consequences that may arise from detection of influenza in a swine herd leading to a major economic loss to the producer. here we outline a surveillance system that has been in place in hong kong for the last decade, based on sampling animals arriving at an abattoir in hong kong. we demonstrate the feasibility of such surveillance in an abattoir setting and compare methods used for detection influenza viruses in swine. virus isolation was carried out by inoculation into mdck cells and by allantoic inoculation in embryonated eggs as previously described. virus isolates were subtyped by haemagglutination inhibition tests using specific antisera and genetically characterized by sequencing and phylogenetic analysis of the haemagglutin gene. , virus detection by rt-pcr a subset of recent specimens was tested in parallel by real time pcr using the biorobot universal system (qiagen) that enables fully-automated viral nucleic acid extraction and downstream reaction setup in a -well plate format. total viral nucleic acids were extracted in a -well plate format with the qiaamp virus biorobot mdx kit (qiagen) on the biorobot universal system (qiagen) according to the manufacturer's instructions. briefly, ll of sample was lysed in ll buffer al, supplemented with ae lg carrier rna in a s block (qiagen), which placed the samples into a well plate format. after protease digestion, samples were transferred to silica based membrane in well plate format for binding. following two washing steps, rna was eluted in ll of elution buffer (buffer ave) into a well elution microplate cl (qiagen) . for the synthesis of cdna, ll of purified rna was used in a ll reaction containing ll of · buffer, ae nm of each deoxynucleotide triphosphate (dntp), mm dithiothreitol, lg random primer, u of rnaseout recombinant ribonuclease inhibitor, and u of superscript iii reverse transcriptase (all from invitrogen). reactions were performed in the geneamp thermocycler (applied biosystems) with the following parameters: minutes at °c, minutes at °c, and soak at °c. subsequent to the reactions, ll of cdna was diluted ⁄ by adding ll of ae buffer (qiagen) . real-time pcr was performed using the power sybrÒ green pcr master mix (applied biosystems) according to the manufacturer's instructions. briefly, ll of ⁄ diluted cdna was amplified in a ll reaction containing ae ll of · power sybr green pcr master mix, nm of forward primer m c ( ¢-ctt cta acc gag gtc gaa acg- ¢) and nm of reverse primer m r ( ¢-agg gca ttt tgg aca aag ⁄ t cgt cta- ¢). the primers have been designed to amplify the sequences in the conserved region of influenza a virus matrix gene, thereby detecting viruses from different species including swine influenza viruses. real-time pcr was performed in the abi fast system (applied biosystems) with the following cycling conditions: minutes at °c once, seconds at °c, and minutes at °c for cycles, followed by melting curve analysis with seconds at °c, minutes at °c, and seconds at °c. in each assay, serially diluted plasmids containing the full length m gene cloned from a ⁄ vietnam ⁄ ⁄ (h n ) were included as standards to perform absolute quantification. a manual baseline was set from cycles - and a manual cycle threshold (ct) was set at ae . samples that were positive or unequivocal results from the real-time pcr were confirmed by performing gel electrophoresis on the pcr products. positive visual identification was made in the presence of the target pcr product at bp in length. a total of tracheal and nasal swabs were processed during the years january -april and yielded influenza virus isolates, an overall virus isolation rate of ae %. of these, were subtype h (classical swine, eurasian avian-like swine, and triple-reassortant), were human-like h viruses, and were eurasian avianlike swine h n viruses. culture in mdck cells yielded % of h subtype viruses, % of the human seasonal-like h n viruses, and ae % of the avian-like eurasian swine h n viruses. culture in embryonated eggs yielded ae % of the h subtype viruses, % of the human seasonal-like h n viruses, and ae % of eurasian avian-like swine h n viruses ( figure ). tracheal and nasal swabs each gave comparable overall virus isolation rates ( ae %). however, isolation rates for human-like h n viruses were ae fold higher in nasal swabs ( ae % versus ae % respectively; p = ae ) ( figure ) . a parallel evaluation of rt-pcr and culture was carried out in specimens. rt-pcr detected ⁄ ( %) of the culture positive specimens. rt-pcr was also positive in ⁄ ( ae %) culture negative specimens, but all these specimens had very low virus load in the rt pcr tests. virus could not be cultured from these culture negative specimens even by attempts at virus re-isolation from the frozen specimen. surveillance in an abattoir setting provides an acceptable yield of influenza viruses and is a feasible method of swine influenza surveillance. sampling in a large abattoir setting allows surveillance to be carried out anonymously with no negative consequences to the supplier. the supply-chain of pigs to the hong kong abattoir involves pigs being trucked in over long distances and may provide opportunity for virus amplification during transport. thus, virus isolation rates may be lower in more vertically integrated and homogenous production and slaughter systems where less mixing of pigs occurs. our results indicate that mdck cell culture is essential for optimizing virus isolation during swine influenza surveillance. allantoic inoculation of embryonated eggs by itself is sub-optimal for isolation of swine influenza viruses. it is however possible that inoculation of embryonated eggs by the amniotic route may lead to better isolation rates than allantoic inoculation. rt-pcr detection is an alternative method for virus detection. but the additional specimens detected by rt-pcr did not yield culturable virus, even following attempts at re-isolation and sequential passage. the rt-pcr positive ⁄ virus isolation negative specimens had very low virus load, and this may be the explanation for the inability to isolate such viruses. in addition, rt-pcr did not detect all viruses isolated by culture. tracheal and nasal swabs gave comparable isolation rates with the exception of human-like h n viruses which were more frequently isolated from nasal swabs. this may suggest that, in contrast to endemic swine influenza virus lineages, these human-like h n viruses are less adapted to replication in the lower respiratory tract. in summary, collection of nasal or tracheal swabs in an abattoir setting together with virus isolation in mdck cells provides a feasible approach to surveillance of swine influenza viruses. kong, kong, - introduction wild waterfowl are the natural reservoir of influenza a viruses (aiv), and they play an important role in the genesis of pandemic influenza. it is suggested that the pandemic virus was purely derived from avian virus, which adapted to humans and caused efficient human-to-human transmission, while the pandemics of and had acquired the viral haemagglutinin, pb polymerase, and in , the neuraminidase gene segments from the avian gene pool. the major regional outbreaks of highly pathogenic avian influenza (hpai) h n in asia, europe, and africa highlight the potential role played by migratory waterfowl in disseminating highly pathogenic influenza viruses. therefore defining the influenza virus gene-pool in wild birds is of vital importance. surveillance was carried out - times weekly from to during the winter months of october to april in the hong kong mai po nature reserve and lok ma chau, hong kong. the hong kong mai po nature reserve and lok ma chau are along the east asia-australian flyway where a peak of more than ducks and grebes congregate every winter. fecal droppings were collected and transported in vials containing ae ml of vtm, which was prepared from m ( ae g ⁄ l), penicillin g ( · u ⁄ l), polymyxin b ( · u ⁄ l), gentamicin ( mg ⁄ l), nystatin ( ae · u ⁄ l), ofloxacin hcl ( mg ⁄ l), and sulfamethoxazole ( g ⁄ l). an aliquot of ll from each swab sample was inoculated into the allantoic cavity of a -to -day-old chicken embryonated egg, and incubated for days at °c. positive ha isolates were subtyped using standard antisera , and rt-pcr was performed with the used of one-step rt-pcr assay (invitrogen) described earlier, followed by sequencing on abi prism xl dna analyzer. the determination of species of origin was performed by dna barcoding of the mitochondrial cyto-chrome oxidase i gene from dna extracted from the fecal droppings. during the -year surveillance period, a total of influenza viruses were isolated from samples collected, an overall isolation rate of ae %. a total of isolates were obtained from specimens collected during the winter period coinciding with the southern migration of waterfowl along the east asian flyway and one isolate obtained from samples collected in spring during the period when northern migration of waterfowl took place along the east asian-australasian flyway. the isolation in hong kong was slightly lower than a similar study conducted in south korea in which the isolation rate of migratory birds was ae % in - . this suggested a slightly lower prevalence of influenza virus present in hong kong as the birds migrated southwards. the viruses isolated in hong kong, representing hemagglutinin (ha) subtypes of h -h and neuramidinase (na) subtypes of n -n , were all from wild waterfowl ( table ) . out of the twelve ha subtypes isolated, h and h were the two subtypes that were isolated frequently every year for h and in six out of seven years for h , respectively. h and h viruses accounted for ae % and ae % of all virus isolated, respectively. on the other hand, h , h , and h were the least prevalence ( ae %) and were only isolated once in years. of the na subtypes, n and n were isolated most often ( ae % and ae % of all isolates, respectively) and n was the least ( ae %). november was the month that had the highest prevalence of influenza virus ( ae % of samples being positive) compared to only ae % in march. the subtype's variation was the most diverse in december during our years of surveillance. this suggested that more of these wild migratory birds may be carrying influenza virus when they arrive in hong kong. however the continued isolation of viruses suggests continued circulation of these viruses in the vicinity of mai po. the study of dna barcoding for the mitochondrial cytochrome oxidase i gene retrieved from fecal droppings revealed that the isolates originated mainly ( ae %) from birds of the order anseriform, family anatidae including eurasian wigeon, northern shoveler, northern pintail, common teal, and garganey. non-anseriformes which were found to have shed aiv viruses were cormorant, grey heron, and stint. none of the water samples collected from the ponds where these birds congregate were found to be positive for the virus. phylogenetic analyses of the ha gene of the lpai h viruses isolated in this study clustered with that of the other lpai h viruses isolated from hokkaido, mongolia, and siberia and were not closely related to the hpai h n . satellite tracking of eurasian wigeons and northern pintails in dec and revealed their flyway from hong kong to as far north as eastern russia, eastern mongolia, and northern china. no hpai h n viruses were isolated in this study from apparently healthy birds. however, as part of the surveillance of dead wild birds carried out by the department of agricultural, fisheries and conservation of the government of hong kong during this same period, over dead wild birds were tested positive for hpai h n and has been reported elsewhere. our influenza surveillance in hong kong has revealed a diversity of influenza virus subtypes the migratory waterfowl infected within the region. the result of the phylogenetic analysis correlated with the findings from satellite tracking that viruses isolated in hong kong were closely related to those isolated in areas along the migratory route. no healthy bird was isolated with hpai h n, although dead wild birds have been regularly found to have hpai h n virus, suggesting that infected birds might not live for a long period. introduction a novel swine-origin h n influenza virus emerged in mexico in april and rapidly spread worldwide, causing the first influenza pandemic of the st century. most confirmed human cases of h n ⁄ influenza have been uncomplicated and mild, but the increasing number of cases and affected persons worldwide warrant optimal prevention and treatment measures. today, almost all of the pandemic h n ⁄ viruses tested are resistant to m blockers. therefore, only the neuraminidase (na) inhibitors are currently recommended for treatment of this pandemic influenza. for the control of influenza infection, the clinical use of oseltamivir has increased substantially during the pandemic. to date, the majority of tested clinical isolates have remained susceptible to na inhibitors, oseltamivir and zanamivir, but oseltamivir-resistant variants with h y na mutation (n numbering) have been isolated from individuals taking prophylaxis, from immunocompromised patients, and from a few community clusters. , in view of the high prevalence of oseltamivirresistant seasonal h n influenza viruses in - , the isolation of resistant h n ⁄ viruses without known oseltamivir exposure raised great concern about the transmissibility and fitness of these resistant viruses. here we studied the transmissibility of a closely matched pair of pandemic h n ⁄ clinical isolates, one oseltamivir-sensitive and one resistant, in both direct contact and respiratory droplets routes among ferrets. viral fitness was evaluated by co-infecting a ferret with both the oseltamivir-sensitive and -resistant viruses. the viruses were also characterized by full genome sequencing, susceptibility to na inhibitors, and growth in mdck and mdck-siat cells. oseltamivir-resistant influenza a ⁄ denmark ⁄ ⁄ (h n ) virus (a ⁄ dm ⁄ ⁄ ) was isolated from the throat swab of a patient who had influenza-like symptoms and received post-exposure oseltamivir prophylaxis ( mg once daily). wild-type influenza a ⁄ denmark ⁄ ⁄ (h n ) virus (a ⁄ dm ⁄ ⁄ ) was isolated from a patient in the same cluster of infection as the a ⁄ dm ⁄ ⁄ virus. to assess growth kinetics of viruses, confluent mdck or mdck siat cell monolayers were infected with viruses at a multiplicity of infection (moi) of approximately ae pfu ⁄ cell (single-step) or ae pfu ⁄ cell (multi-step). supernatants were collected every h or h p.i. for time points. a modified fluorometric assay using the fluorogenic substrate ¢-( -methylumbelliferyl)a-d-n-acetylneuraminic acid (munana) was used to determine viral na activity. the drug concentration required to inhibit % of the na enzymatic activity (ic ) was determined by plotting the percent inhibition of na activity as a function of compound concentration calculated in the graphpad prism (la jolla, ca) software from the inhibitor-response curve. na enzyme kinetics were determined by measuring na activity every seconds for minutes under the same conditions as above, when all viruses were standardized to an equivalent dose of ae pfu ⁄ ml. the k m and v max were calculated by fitting the data to the appropriate michaelis-menten equations using nonlinear regression in the graphpad prism software. young adult ferrets ( - months of age) were obtained from the ferret breeding program at st. jude children's research hospital. all ferrets were seronegative for influenza a h n and h n viruses and for influenza b viruses. for transmission studies, the donor ferrets were lightly anesthetized with isoflurane and inoculated intranasally with tcid virus in ae ml sterile pbs . after the donor ferrets were confirmed to shed virus on day p.i., each donor was then housed in the same cage with two naïve direct-contact ferrets. two additional recipient ferrets were placed in an adjacent cage isolated from the donor's cage by a two layers of wire mesh (approximately cm apart) that prevented physical contact but allowed the passage of respiratory droplets. ferret weight and temperature were recorded daily for days. nasal washes were collected from donors and recipients on day , , , , , , , and p.i. by flushing both nostrils with ae ml pbs, and tcid titers were determined in mdck cells. serum samples were collected weeks after virus inoculation, and were tested for seroconvention by hi assay. full genome sequencing revealed that the pair of h n ⁄ viruses differed only at na amino acid position , where the pandemic a ⁄ dm ⁄ ⁄ virus had an h y amino acid mutation caused by a single t-to-c nucleotide substitution at codon . the wild-type a ⁄ dm ⁄ ⁄ was susceptible to oseltamivir carboxylate (mean ic : ae nm), but the a ⁄ dm ⁄ ⁄ carrying the h y na mutation had ic values approximately - times of the wild-type viruses (mean ic : nm). the ic of zanamivir was comparable for both viruses and were uniformly low (mean ic £ ae nm). the h y na mutation confers resistance to oseltamivir carboxylate but did not alter susceptibility to zanamivir. to understand the impact of the h y mutation on the na enzymatic properties, na enzyme kinetics was determined. the na of the oseltamivir-resistant virus had a slightly higher k m (mean = lm) and lower v max (mean = u ⁄ sec) than na of the sensitive virus (k m , mean = lm; vmax, mean = u ⁄ sec). the results suggested that the h y na mutation reduced na affinity for substrate and na catalytic activity, although the function of na was not severely impaired. to further evaluate the impact of the h y na mutation on virus growth in vitro, single-and multi-cycle growth studies of both viruses were performed in mdck and mdck-siat cells. in the both single-and multiple-cycle growth curves, the two viruses reached comparable levels eventually, but the initial growth of the resistant virus was significantly delayed by at least - logs in comparison to that of wild-type virus (p < ae ). the donor ferrets inoculated with wild-type a ⁄ dm ⁄ ⁄ or oseltamivir-resistant virus shed virus productively until day or day p.i., with a peak virus titer comparable to that of a ⁄ dm ⁄ ⁄ virus (table ). in a ⁄ dm ⁄ ⁄ virus group, two of direct-contact ferrets the weight loss in ferrets is the maximum percentage loss compared with the initial weight. virus shedding is indicated as number of virus-shedding animals ⁄ total number; mean peak virus titer (log tcid ⁄ ml) in nasal wash samples is indicated in parentheses. serum hemagglutination inhibition (hi) titer to homologous virus in ferret serum was determined on day p.i. duan et al. and of respiratory droplet-contact ferrets were infected through virus transmission, as indicated by the virus titers and inflammatory cell counts in their nasal washes and also by sero-conversion. under identical conditions, in a ⁄ dm ⁄ ⁄ group, only of direct-contact ferrets were infected through virus transmission, but neither respiratory droplet-contact ferrets was infected, as confirmed by the absence of sero-conversion (table ) . virus shedding in the direct-contact ferrets was lower and peaked after a longer interval in this group than in the oseltamivir-sensitive a ⁄ dm ⁄ ⁄ group (table ) , but the resistant viruses appeared to cause a similar disease course in ferrets without apparent attenuation of clinical signs. these results showed that an oseltamivir-resistant h y mutant of pandemic h n virus, a ⁄ dm ⁄ ⁄ virus could be only transmitted efficiently by direct contact. to compare the relative fitness, growth capability, and transmissibility of the sensitive and resistant h n ⁄ viruses within host, a donor ferret was co-inoculated with a : ratio of the sensitive and resistant viruses, and another two naive ferrets were housed with the donor to test direct contact. during co-infection, the pattern of virus shedding and the clinical signs were similar to those in ferrets inoculated with either a ⁄ dm ⁄ ⁄ or a ⁄ dm ⁄ ⁄ virus (table ). in the inoculated donor ferret, the virus population in the nasal washes remained mixed but wild-type viruses outgrew the resistant virus progressively ( figure ). two of direct-contact ferrets were infected through virus transmission, but only wild-type virus was detected in both direct-contact ferrets ( figure ). in summary, oseltamivir-sensitive a ⁄ dm ⁄ ⁄ virus possessed better growth capability in the upper respiratory tract than did resistant a ⁄ dm ⁄ ⁄ virus, and thus had an advantage in directcontact transmission. our study determined the comparative transmissibility of two naturally circulating oseltamivir-sensitive and -resistant pandemic h n ⁄ viruses; we demonstrated inefficient respiratory-droplet transmission of an oseltamivir-resistant h y mutant of pandemic h n virus among ferrets, although it retained efficient direct-contact transmission. we suggest that the lower fitness of resistant virus within the host along with its reduced na function and delayed growth in vitro may in part explain its less efficient transmission. notably, the h y mutant of h n ⁄ used in this study was the first oseltamivir-resistant h n ⁄ isolate from a patient on oseltamivir prophylaxis to be characterized for transmissibility. our observation in the animal model is consistent with the epidemiological data collected from humans, which showed no evidence of predominant or continued circulation of oseltamivir-resistant viruses. as this study was undertaken, additional h y mutants of h n ⁄ viruses have emerged in the absence of oseltamivir use. , the emergence of these viruses should raise concerns as to whether resistant h n ⁄ viruses will acquire greater fitness and spread worldwide as the naturally resistant h n viruses did during the - season. two independent studies have evaluated the pathogenecity and transmission of other oseltamivir-resistant pandemic h n ⁄ clinical isolates in the animal models. , one of the studies, which also used an oseltamivir-resistant virus isolated from a patient under oseltamivir prophylaxis, observed similar results as ours: although the respiratory-droplet route of transmission was not investigated, it was shown that the resistant isolate was transmitted though direct-contact route and was as virulent as wild-type virus in ferrets. in another study, two oseltamivir-resistant isolates were transmitted through the respiratory-droplet route in ferrets, and the dynamics of transmission were different between the two isolates. apparently, these two oseltamivir-resistant isolates were still unequal in their transmissibility and were disparate from the resistant isolate in our study. the isolation history of the two resistant isolates was unclear in this study, and this would be an important factor to understand the fitness of drug-resistant viruses. further studies with more clinical isolates of diverse isolation background are warranted to identify how these novel h y mutants of pandemic h n ⁄ virus have changed to retain their full transmissibility. taken together, all these related studies underline the necessity of continuous monitoring of drug resistance and characterization of potential evolving viral proteins. this study was supported by contract hhsn c from the national institute of allergy and infectious diseases, national institutes of pigs have been considered as hypothetical ''mixing vessels'' facilitating the genesis of pandemic influenza viruses. , the pandemic h n ⁄ virus (ph n ⁄ ) contained a very unique genetic combination and was thought to be of swine origin, as each of its eight gene segments had been found to be circulating in pig populations for more than a decade. however, such a gene constellation had not been found previously in pig herds all around the world. only after its initial emergence in humans has this virus been repeatedly detected in pigs, and found to further reassort with other swine influenza virus. [ ] [ ] [ ] a primary question remaining to be answered is whether the ph n ⁄ -like and their genetically related viruses could become established in pig populations, thereby posing novel threats to public health. despite the fact that ph n ⁄ first appeared in mexico and the united states, and six of its eight gene segments were derived from the established north american triple reassortant swine influenza virus (trig), its neuraminidase (na) and matrix protein (m) genes belonged to the eurasian avian-like swine lineage (ea), which had never been detected in north america previously. , likewise, the trig-like viruses were never reported in europe. in contrast, both lineages of virus were frequently detected in asia, and reassortants between them have also been documented in recent years. , this has given rise to a complicated ecological situation, i.e. the simultaneous prevalence of multiple genotypes of h n and h n viruses in pigs. , among them, two representative reassortants showed the most similar genotypic characterization to the ph n ⁄ virus, the sw ⁄ hk ⁄ ⁄ (h n ) and sw ⁄ hk ⁄ ⁄ (h n ), which respectively harbor seven and six gene segments closely related to the pandemic strains. , to understand their in vivo characteristics and zoonotic potential, these two viruses, together with a human prototype strain and a swine ph n ⁄ -like isolate, were chosen for a study of their pathogenicity and transmissibility in domestic pigs, ferrets, and mice. the prototype ph n ⁄ virus, a ⁄ california ⁄ ⁄ (ca ), was provided by the world health organization collaborating centers for reference and research on influenza (atlanta, ga, usa). three ph n ⁄ -related swine influenza viruses were isolated through our surveillance program in south china as previously described. , the a ⁄ swine ⁄ guangdong ⁄ ⁄ (h n , gd ) virus was a ph n ⁄ -like swine isolate. a ⁄ swine ⁄ hong kong ⁄ ⁄ (h n , hk ), the closest pandemic ancestor known to date, possesses an m gene derived from the ea lineage, with the other gene segments from trig viruses. a ⁄ swine ⁄ hong kong ⁄ ⁄ (h n , hk ), a recent pandemic reassortant progeny, had a ph n ⁄ like na gene (also belonging to the ea lineage), an ea-like hemagglutinin (ha) gene, and six trig-like internal genes. all viruses were propagated in madin-darby canine kidney (mdck) cells for three passages, and their titers were determined by plaque assays. all experiments with live viruses were conducted in biosafety level (bsl- ) containment laboratories. pigs ( - week old, n = - ) and ferrets ( month old, male, n = ) were intranasally infected with pfu of each virus, and mice ( ) ( ) week old, female balb ⁄ c, n = ) with a dose of pfu. naïve uninfected pigs (n = ) were co-housed in the same cage with the inoculated ones from each group. body weights and clinical signs were recorded daily. virus replication was determined by titration of the virus in nasal and rectal swabs (pigs), nasal washes (ferrets), as well as from lungs and other organs (pigs and mice). seroconversion was tested by hemagglutination inhibition (hi) assays. histopathological and immunohistochemical analysis were performed as previously described. statistical analysis was performed by mean analysis with pasw statistics (spss inc., chicago, il, usa). the probability of a significant difference was computed using anova (analysis of variance). results were considered significant at p < ae . the pathogenicity of the four viruses tested differed significantly in inoculated mice. animals infected with pfu of hk experienced the most severe body weight loss ( ae ± ae %) but started to recover after days post-infection (dpi). hk caused similar peak body weight loss ( ae ± ae % on dpi) in mice as did ca ( ae ± ae %, on dpi), but the onset of clinical signs and weight loss (on dpi) was day later than those caused by the other three viruses. the gd -infected group suffered the least body weight loss ( ae ± ae %, dpi) and was the earliest to recover. although all four viruses were detected in the lungs with comparable virus titers on dpi (p > ae ), mice inoculated with gd consistently showed the lowest lung index (lung weight ⁄ body weight, %) on , , and dpi (p < ae ), suggesting the slightest injury and consolidation of the lungs. in concordance with the body weight change, the lung index from the hk group was higher than that from any other groups on and dpi, indicating the marked virulence of hk in mice. notably, virus titer of hk in the nasal turbinate was lower than the other groups both on and dpi (p < ae ), but virus replication in the lower respiratory tract was either higher (in the trachea) or similar (in the lungs). observations of the body weight changes caused by infection of ph n ⁄ or its genetically related swine viruses in ferrets have come to a similar conclusion as that for the mouse experiment. after nasal inoculation with pfu of each virus, all groups of ferrets experienced transient body weight loss for - days, except for those infected with gd , which showed no significant weight loss (p > ae ). although ferrets from the ca -infected group reached their peak weight loss ( ae ± ae %, dpi) one day earlier than those from the hk and hk groups, they began to regain body weight quickly thereafter. hk -infected ferrets also recovered rapidly and their body weights reached the same level as those of the gd -infected group at dpi. comparatively, ferrets inoculated with hk had the most retarded body weight recovery, which did not get back to the baseline level until dpi. hk was only detectable in the nasal wash on dpi, whereas the duration of virus shedding for gd , hk , and ca was - days. by combining the data obtained from the virus titration in the mouse turbinate and ferret nasal washes, a possible conclusion can be made that hk may have lower transmissibility than the other three viruses. after inoculation or exposure by direct contact (physical contact) with the ph n ⁄ virus and its close relatives, most pigs experience no or mild symptoms, such as slight loss of appetite and inactivity. body weight loss was only recorded in pigs inoculated with hk during the second week post-inoculation, but not in their contact pigs or in the other groups. diarrhea was observed intermittently in each of the inoculated or contact groups throughout the experiment, and viruses could be recovered in the rectal swabs, saliva, drinking water, and environmental swabs (inner cage walls accessible to the pigs) at various time points. however, virus titers in the positive rectal swabs were just slightly above the detection limit, while those from the environment sometimes could be higher. whether these viruses can replicate in the digestive tract or were just carried-over by contaminated foods and water requires further investigation. although virus could be detected in the nasal swabs of all infected or contact animals, the lowest peak titer was from pigs inoculated or in contact with hk ( ae - ae log tcid ⁄ ml lower than the other groups), suggesting unfavorable replication in the nasal cavity for this virus. postmortem examination on and dpi revealed that pigs infected with hk had the most extensive gross lesions in the lungs, and histochemical staining of viral nucleoprotein (np) in lung tissues on dpi also suggested the best replication for hk in the lower respiratory tract. on days post-contact (dpc), all pigs exposed to the inoculated animals developed sero-conversions (hi = - ) except for one from the gd contact group. however, on dpc, its hi titer reached , indicating slower seroconversion. this study revealed that both the pandemic h n and its genetically related swine viruses could readily infect mice, ferrets, and pigs causing mild to moderate clinical symptoms. they could also transmit efficiently between pigs. when compared with the pandemic stains and its reassortant progeny (hk ), the hk (h n ) virus containing the ea-like m gene in the genetic context of the trig virus showed consistently higher virulence in all three mammalian models tested, but it is still unknown what might happen if such a virus further reassorts to obtain the pandemic-like or ea-like na gene. however, our findings suggest that pigs could likely maintain the prevalence of different genotypes of pandemic-related influenza viruses, and highlight the zoonotic potential of multiple strains of swine influenza virus. pandemic influenza viruses emerge from the animal reservoirs. among the three pandemics that occurred in the last century, we learned that the h n and the h n pandemic viruses emerged by reassortment between circulating human virus and avian-origin influenza virus(es). studies on the emergence of the catastrophic spanish h n virus suggest that the virus may have obtained all of its eight gene segments from the avian reservoir, , or alternatively is a reassortant between mammalian and a previously circulating human influenza virus. over years since the last pandemic, the first pandemic in the st century arose in and was caused by a swine-origin influenza virus containing a unique gene combination, with gene segments derived from the circulating north america ''triple reassortant'' (pb , pb , pa, ha, np, and ns) and the ''eurasian'' (na and m) swine influenza viruses. , analysis of the pandemic h n viruses failed to identify known molecular markers predictive of adaptation to humans. the ''triple reassortant'' swine influenza viruses emerged in late s in north america is a reassortant between classical swine (descendent of the virus after adaptation in swine population), avian, and human influenza viruses. the eurasian influenza virus was originally an avian influenza virus that was introduced into the european swine population in the late s. , while incidents of zoonotic infection with triple reassortant or eurasian influenza in humans have been reported, , sustained human-to-human transmission has never been established. these results suggest that the unique gene combination seen with the pandemic h n viruses may confer its transmissibility among humans. we have carried out systematic prospective surveillance of swine influenza in southern china over that last years through samples routinely collected at an abattoir in hong kong. during this time, the surveillance results suggest co-circulation of classical swine h n , triple reassortant h n , eurasian swine h n , and a range of reassortants between these three virus lineages. , ferrets have been reported as a suitable model for the study of influenza transmission as they are naturally susceptible to influenza infection, exhibit similar clinical signs (including sneezing), and possess receptor distribution in the airway similar to that of humans. [ ] [ ] [ ] to identify molecular determinants that enable sustained human-to-human transmission, we compared the pandemic virus with genetically related swine influenza viruses obtained from this surveillance program for their ability to transmit from ferret to ferret by direct contact or aerosol transmission. viruses human h n influenza virus [a ⁄ wuhan ⁄ ⁄ (wuhan )] and pandemic h n influenza viruses [a ⁄ california ⁄ ⁄ (ca )] were included for the study. swine influenza viruses that are genetically related with the pandemic h n virus were selected from our surveillance system, including classical swine-like influenza virus a ⁄ sw ⁄ hk ⁄ ⁄ (h n ) (swhk ), triple reassortant-like a ⁄ sw ⁄ arkansas ⁄ ⁄ (h n ) (swar ), and one reassortant between triple reassortant and eurasia swine influenza viruses [a ⁄ sw ⁄ hk ⁄ ⁄ (h n ) (swhk )]. swhk contains seven gene segments (pb ,pb ,pa,ha,np,m,ns) closely related to the pandemic h n viruses. transmissibility was tested in -to -month-old male ferrets obtained from triple f farm (sayre, pa); all ferrets were tested to have hi titer £ against human seasonal influenza h n (a ⁄ tennessee ⁄ ⁄ ), h n (a ⁄ brisbane ⁄ ⁄ ), and influenza b (b ⁄ florida ⁄ ⁄ ) prior the experiments. in each virus group, three ferrets were inoculated with tcid of the virus. at day postinoculation (dpi), we introduced one naïve direct contact ferret to share the cage with inoculated ferret, and one naïve aerosol contact ferret into the adjacent compartment of the cage separated by a double-layered perforated divider. nasal washes were collected every other day and tested for influenza virus antigen and to determine viral titers (tcid ). weight changes, temperature, and clinical signs were monitored daily. transmission is defined by detection of virus from nasal washes and ⁄ or by seroconversion (> fold rise in the post-sera collected after - days post contact). experiments were performed in the p + laboratory at st. jude children's research hospital. all studies were conducted under applicable laws and guidelines and after approval from the st. jude children's research hospital animal care and use committee. at tcid inoculation dose, all viruses replicated efficiently in the ferret upper respiratory tract with peak titers detected from inoculated ferrets at dpi. lower peak titers were detected from swhk and swhk inoculated ferrets, however, the differences were not statistically significant (table ) . tissues collected from inoculated ferrets at dpi showed that pandemic h n and swine influenza viruses replicated both in the upper and lower respiratory tract of the ferrets, while the replication of human seasonal influenza wuhan was restricted in the upper respiratory tract. direct contact transmission from inoculated donor ferrets to their cage-mates was observed for all viruses studied, albeit at different efficiency. human seasonal influenza (wuhan ) and pandemic h n viruses (ca ) transmitted most efficiently via direct contact route as the virus can be detected on dpi from direct contact ferrets, and the peak titers were detected on dpi from direct contacts. moderate direct contact transmission efficiency was detected from swar and swhk viruses as the virus can be detected from direct contact ferrets at dpi, with peak titers detected at dpi or dpi. classical swine-like swhk showed least efficient contact transmission as virus could be detected from all direct contacts only at dpi, and the peak titer detected on dpi. aerosol transmission was detected in groups of human seasonal influenza virus wuhan ( ⁄ ), pandemic h n influenza virus ca ( ⁄ ), as well as swine precursor virus swhk ( ⁄ ). transmission of wuhan and ca to aerosol contacts was detected at dpi or dpi, while transmission of swhk was detected later at dpi, suggesting that the swhk virus possessed aerosol transmission potential, but may require further adaptation to acquire efficient aerosol transmissibility. in addition to viral detection from nasal washes, we also detected viruses from the rectal swabs of ferrets inoculated or infected with pandemic h n viruses (ca ) or classical swine-like virus (swhk ), which share the common origin for the ha, np, and ns gene segments. while many of the swine influenza viruses studied were able to transmit via the direct contact route, swhk , which shares a common genetic derivation for seven genes with h n pdm, possessed capacity for aerosol transmission, albeit of moderate efficiency. swhk differed from swine triple reassortant viruses in the origins of its m gene. it is possible that the m gene derived from eurasian avian- like swine viruses also contributes to the transmissibility of h n pdm influenza viruses. outbreaks of highly pathogenic avian influenza (hpai) of the h n subtype are of extreme concern to global health organisations as human infection can result in severe acute respiratory distress syndrome, multi-organ failure, and coma. hpai viruses of either h or h subtypes contain a characteristic multi-basic cleavage site in the hemagglutinin glycoprotein as well as other virulence factors that expand the viral tropism beyond the respiratory tract of poultry. there is also emerging evidence of viral rna or antigen in multiple organs and the cns of humans infected with h n that is consistent with systemic infection , and raises the question of the role of the cleavage site in dissemination of the virus in this species. the majority of human cases with h n have involved contact with sick or contaminated poultry and exposure to respiratory secretions of birds that can be inhaled and ingested. particular risk factors for h n infection include bathing with sick birds, improper hand washing after handling sick birds, or slaughtering poultry. viral inoculum may also be consumed directly during a variety of religious and cultural practices, such as drinking contaminated duck blood and kissing of merit release birds. h n infection is lethal in % of human cases, and the pathogenetic mechanisms leading to this level of mortality are unclear. to date cases have been reported to the who, although many more people have potentially been exposed to h n through contact with infected bird populations. some studies have suggested that genetic factors may predispose an individual to severe h n disease, but little is known about the influence of route of virus exposure on morbidity and mortality. in ferrets, an animal model frequently used to study influenza because of its similar disease profile to humans, swayne et al. observed that exposure to a virulent h n strain a ⁄ vietnam ⁄ ⁄ by intra-gastric gavage did not lead to disease and did not generate an antibody response, whereas ferrets that experienced a more natural exposure by being fed contaminated meat developed severe signs of infection. in this study we further assessed the disease profile of h n following a natural oral exposure in the ferret model. to achieve this inoculation condition, conscious ferrets voluntarily consumed a liquid inoculum of h n hpai strain a ⁄ vietnam ⁄ ⁄ . as a comparison anesthetised ferrets were exposed by intranasal administration of inoculum and the ensuing disease profiles of the different routes of infection were compared. eight ferrets per group were inoculated with egg infectious dose of a ⁄ vietnam ⁄ ⁄ in a volume of ll that was given to the nares of anaesthetized ferrets to establish a total respiratory tract (trt) infection or voluntarily consumed by conscious ferrets to establish an oral infection. ferrets were culled at a predetermined humane endpoint that was defined as either a > % weight loss and ⁄ or evidence of neurological signs, discussed in ; animals that did not reach the humane endpoint were euthanased on day after challenge. nasal washes and oral swabs collected during the course of infection and organ homogenates were assessed for the presence of replicating virus by growth in embryonated-chicken eggs; viral loads were determined by titration on vero cells and expressed as tcid . tissue samples were fixed with formalin and embedded in paraffin for sectioning. viral lesions were identified by hematoxylin and eosin staining of the sections and the presence of viral antigen in the sections was determined by staining with antibody to influenza a nucleoprotein. pre-and post-exposure antibody responses were assessed by hemagglutination-inhibition assays using irradiated a ⁄ vietnam ⁄ ⁄ virus. the majority ( %) of ferrets infected by the trt route rapidly became inactive, developed severe disease, and were euthanased at the humane endpoint following infection ( figure ). ferrets infected orally had an improved chance of survival, as only % of animals developed severe disease (figure ), and the surviving ferrets were more active than ferrets infected by the trt throughout the stage of acute infection (data not shown). the improved survival rate and wellbeing of ferrets infected orally was not a result of poor infection rates by this route, as of surviving ferrets developed h specific antibodies by day post-infection, and they did not have pre-existing antibodies to h n (data not shown). the two ferrets that developed severe disease after oral infection had similar disease profiles to ferrets infected by the trt route; they both progressed to a > % weight loss and exhibited neurological signs (data not shown). viral loads in organs of these two ferrets confirmed dissemination to extra-pulmonary sites (table ) : replicating virus was detected at high titres in the spleen, pancreas, liver, and brain. similar findings were recorded in ferrets with trt infections in this study (not shown) and elsewhere. viral load in nasal washes and oral swabs taken at days , , and post-infection by the oral route did not correlate with the development of severe disease, and virus was isolated only sporadically and at low titre from the nasopharynx of these animals (data not shown). interestingly, the two ferrets with severe disease after being infected orally had no detectable viral antigen or lesions in the olfactory epithelium and bulb (table ) , whereas of ferrets culled after infection by the trt route had lesions and viral antigen in both the olfactory epithelium and bulb (data not shown). trt oral figure . percentage of ferrets that survived infection after oral or trt infection. ferrets were exposed to a ⁄ vietnam ⁄ ⁄ by the total respiratory tract (trt) route (circles) or the oral route (triangles). the percentages of ferrets that survived infection are indicated at each day following challenge. ferrets exposed orally were more likely to survive h n infection than ferrets exposed to the same dose of virus by the trt. the improved survival rates that were observed after an oral infection could be a consequence of low-level viral replication in the upper respiratory tract in combination with delivery of a substantial portion of the inoculum directly to the stomach where it may have been inactivated by the harsh environment of the gastro-intestinal tract. most ferrets infected orally developed an h -specific antibody response which differs from the studies of swayne et al. in which ferrets gavaged with a liquid inoculum neither developed signs of disease nor an antibody response. however swayne et al. administered virus to anaesthetized ferrets by gastric gavage that would have bypassed the oropharynx. in our study virus was administered to the oral cavity directly and would have had access to the oropharynx. low level of replication at this site may have been sufficient to trigger an antibody response. the two ferrets that developed severe disease following oral infection had a similar profile of viral dissemination as ferrets infected by the trt route. differences were seen in the olfactory epithelium and bulb as lesions, and viral antigen did not occur in these sites following oral infection, although cerebral involvement was identified. one route of dissemination of h n into the cns may be by transport within nerves through the olfactory bulb into the cerebrum. due to the absence of lesions and antigen in these sites following oral infection the spread of virus into the brain in these two animals may be occurring through involvement of other cranial nerves or the hematagenous routes. nasal turbinates ) ae ) ) ) ) pharyngeal lymph node interactions of oseltamivir-sensitive and -resistant highly pathogenic h n influenza viruses in a ferret model < ae b ) + + + + olfactory epithelium nd a nd ) ) ) ) olfactory bulb nd nd ) ) ) ) trachea < ae ) ) nd ) nd lung ) < ae + + ) + spleen ae ) + + ) + small intestine ) ) ) ) ) + pancreas ) ae + ) + + the pandemic potential of highly pathogenic h n influenza viruses remains a serious public health concern. while the neuraminidase (na) inhibitors are currently our first treatment option, the possibility of the emergence of virulent and transmissible drug-resistant h n variants has important implications. clinically derived drug-resistant viruses have carried mutations that are na subtype-specific and differ with the na inhibitor used. the most commonly observed mutations are h y and n s in the influenza a n na subtype (n numbering here and throughout the text); e a ⁄ g ⁄ d ⁄ v and r k in the n na subtype; and r k and d n in influenza b viruses. h n influenza viruses isolated from untreated patients are susceptible to the na inhibitors oseltamivir and zanamivir, although oseltamivir-resistant variants with the h y na mutation have been reported in five patients after , or before drug treatment; and the isolation of two oseltamivir-resistant h n viruses with n s na mutation from an egyptian girl and her uncle after oseltamivir treatment were described. the impact of drug resistance would depend on the fitness (i.e., infectivity in vitro, virulence, and transmissibility in vivo) of the drug-resistant virus. if the resistance mutation only modestly reduces the virus' biological fitness and does not impair its replication efficiency and transmissibility, the effectiveness of antiviral treatment can be significantly impaired. the recombinant wild-type h n influenza a ⁄ vietnam ⁄ ⁄ (vn-wt), a ⁄ turkey ⁄ ⁄ (tk-wt) viruses, and oseltamivir-resistant viruses with h y na mutation (vn-h y and tk-h y) were generated by using the -plasmid reverse genetics system. susceptibility to na inhibitors was tested by using a fluorescence-based na enzyme inhibition assay with munana substrate at a final concentration of lm. viral fitness was studied in vivo in a ferret model: groups of three ferrets were lightly anesthetized with isoflurane and inoculated intranasally with vn-wt, vn-h y, or mixtures of the two at a different ratios at a dose of pfu in ae ml pbs; they were inoculated with tk-wt, tk-h y, or mixtures of the two at a different ratios at a dose of pfu in ae ml pbs. respiratory signs (labored breezing, sneezing, wheezing, and nasal discharge), neurologic signs (hind-limb paresis, ataxia, torticollis, and tremor), relative inactivity index, weight, and body temperature were recorded daily. virus replication in the upper respiratory tract (urt) was determined on days , , and p.i. the competitive fitness (i.e., co-inoculation of ferrets with different ratios of oseltamivir-resistant and -sensitive h n viruses) was evaluated by the proportion of clones in day- nasal washes that contained the h y na mutation. na mutations were analyzed by sequence analysis of individual clones ($ clones ⁄ sample) created by ligation of purified pcr products extracted from nasal wash samples into a topo vector. introduction of the h y na mutation conferred high resistance to oseltamivir carboxylate in vitro; the mean ic of the vn-h y and tk-h y viruses was and times, respectively, that of the corresponding wildtype viruses. the oseltamivir ic of the tk-wt virus was $ times that of the vn-wt virus. all four recombinant h n viruses were susceptible to zanamivir. introduction of the h y na mutation reduced $ % and % of the na activity of vn-h y and tk-h y viruses, respectively, as compared to the wild-type virus activity (p < ae ; two-tailed t-test). all ferrets inoculated with either vn-wt or vn-h y virus exhibited acute disease signs (high fever, marked weight loss, anorexia, extreme lethargy), rapid progression, and death by day - p.i., and no differences in clinical signs and replication in the urt of ferrets were observed between wild-type and oseltamivir-resistant viruses ( table ) . both of the tk viruses caused milder illness than did the vn viruses, despite a much higher dose ( pfu ⁄ ferret), and the tk-h y virus caused less weight loss and fever than the tk-wt virus (table ) . however, competitive fitness experiments revealed a disparity in the growth capacity of vn-h y and tk-h y viruses as compared to their wild-type counterparts: clonal analysis established the uncompromised fitness of vn-h y virus and the impaired fitness of tk-h y virus (table ) . although, the trend towards an increase ⁄decrease in the frequency of the h y na mutation relative to the wild-type was statistically significant (p > ae ) for two studied groups only. mutations within the na catalytic (r k) and framework (e a ⁄ k, i l, h l, n s) sites or near the na active enzyme site (v i, i t ⁄ v, q h, k n, a t) emerged spontaneously (without drug pressure) in both pairs of viruses (results not shown). the na substitutions i v and e a could exert compensatory effect on the fitness of vn-h y and tk-h y viruses. the lethality and continuing circulation of h n influenza viruses warrants an urgent search for an optimal therapy. our results showed that the h y na mutation affects the fitness of two h n influenza viruses differently: the oseltamivir-resistant a ⁄ vietnam ⁄ ⁄ -like virus outgrew its wild-type counterpart, while the oseltamivir-resistant a ⁄ turkey ⁄ ⁄ -like virus showed less fitness than its wild-type counterpart. we used a novel approach to compare the fitness of oseltamivir-sensitive and -resistant influenza viruses that included analysis of virus-virus interactions within the host (competitive fitness) during co-infection with these viruses. although mixed populations were present in the urt of ferrets on day p.i., the fitness of vn-h y virus was uncompromised as compared to that of its drug-sensitive counterpart, while that of tk-h y virus was impaired. a minor population of na inhibitor-resistant variants may gain a replication advantage under suboptimal therapy in two ways: (i) preexisting variants less sensitive to the drug are selected from the quasispecies population, leading to an increase of the number of resistant clones, and (ii) outgrowing variants may acquire additional compensatory mutations that enhance their fitness. it is possible that use of antiviral drugs (particularly at suboptimal concentration) against mixtures of oseltamivir-resistant and sensitive viruses will promote the spread of drug-resistant variants * ferrets in all groups inoculated with a ⁄ vietnam ⁄ ⁄ virus died by day - p.i. and were observed once daily for days. ** results obtained from one ferret. *** by inhibiting drug-sensitive variants that are competing with them for the dominance in the infected host. the influence of multiple genes on the fitness of viruses carrying h na mutation cannot be excluded. in our study we focused on additional na mutations, and sequence analysis of individual na clones was done to identify potential host-dependent and compensatory na mutations. we found that the na mutations e a and n s, which confer cross-resistance to oseltamivir and zanamivir, , can emerge spontaneously in clade . h n influenza virus in ferrets. further, we observed that mutations at na catalytic (r k) and framework (i l and n s) sites and in close proximity to the na enzyme active site (v i, i t ⁄ v, q h, k n, a t) emerged without drug pressure in both pairs of h n viruses. compensatory mutations in na or other genes may mitigate any fitness cost imposed by resistance mutations. our study identified six potential compensatory na changes (d v, f s, i v, e a, h l, and f s) that may affect the fitness of viruses with the h y na mutation. we suggest that na mutations at residues i v and e a are of importance. interestingly, we observed differences in predominance of i v and e a na mutations in different genetic backgrounds: i v mutation was identified in a ⁄ vietnam ⁄ ⁄ (h n )-like and e a in a ⁄ turkey ⁄ ⁄ (h n )-like genetic background. moreover, i v na mutation was identified only when ferrets were inoculated with the mixtures of vn-wt and vn-h y viruses, but not in ferrets inoculated with vn-h y virus. none of the potential compensatory na mutations was identified in the original inoculum used to infect ferrets. the h y na mutation causes a large shift in the position of the side chain of the neighboring e residue, which must form a salt bridge with r to accommodate the large hydrophobic pentyl ether group of oseltamivir. residue i is located near the na active site, and although it does not alter polarity, it results in a shorter side-chain and, thus, may indirectly affect the residues in the na active site. we suggest that antigenic and genetic diversity, virulence, the degree of na functional loss, and differences in host immune response and genetic background can contribute to the observed differences in the fitness of h n influenza viruses. therefore, the risk of emergence of drugresistant influenza viruses with uncompromised fitness should be monitored closely and considered in pandemic planning. this study was supported by contract hhsn c from the national institute of allergy and infectious diseases, national institutes of health, and by the american lebanese syrian associated charities (alsac). the data presented in the manuscript have been published at: govorkova ea, ilyushina na, marathe bm, mcclaren laninamivir (r- ) is a strong na inhibitor against various influenza viruses, including oseltamivir-resistant viruses. [ ] [ ] [ ] [ ] [ ] [ ] we discovered a single intranasal administration of laninamivir octanoate (cs- ), a prodrug of laninamivir, showed a superior anti-virus efficacy in mouse and ferret infection models compared to repeated administra-tion of oseltamivir and zanamivir. [ ] [ ] [ ] this suggested that cs- works as a novel long-acting na inhibitor of influenza virus in vivo. a single inhalation of cs- proved noninferiority in adult patients and significantly superior in child patients, compared to an approved dosage regimen of oseltamivir for treatment. cs- has been commercially available as an inhaled drug, inavir Ò , for the treatment of influenza in japan since october . the long-acting characteristics of cs- are explained by several reasons. first, cs- was quickly hydrolyzed to an active metabolite, laninamivir, after an intranasal administration to mice, and was retained for a long time as laninamivir in target organs, such as lung and trachea. however, with an intranasal administration of laninamivir, it disappeared quickly and did not demonstrate its longlasting characteristics. another reason is a strong binding of laninamivir to nas of seasonal influenza viruses compared to other three na inhibitors, oseltamivir carboxylate, zanamivir, and peramivir. in the following, the tight-binding ability of laninamivir to pandemic (h n ) na, as well as to the seasonal influenza virus nas, was demonstrated. in addition, we present a hypothesis of the mechanism of the long-lasting property of cs- in mouse based on a localization of an enzyme that hydrolyzes cs- to laninamivir. the influenza viruses, pandemic(h n ) (inf ), a ⁄ new caledonia ⁄ ⁄ (h n ), a ⁄ panama ⁄ ⁄ (h n ), and b ⁄ mie ⁄ ⁄ were treated with excess na inhibitors, such as oseltamivir carboxylate, zanamivir, peramivir, and laninamivir, and then unbound na inhibitors were removed from the mixtures with a bio-spin column bio-gel p- (bio-rad laboratories, hercules, ca, usa). the na substrate, -methylumbelliferyl-n-acetyl-a-d-neuraminic acid (nacalai tesque, japan) was added to the virus-na inhibitor complex, and the na activities were followed for hours at room temperature by measuring the fluorescence at an excitation wavelength of nm and an emission wavelength of nm. the enzyme which hydrolyzes cs- to laninamivir was partially purified from rat lungs using ion exchange column chromatography, and almost all bands separated by an sdspolyacrylamide gel electrophoresis were identified by mass spectrometry. the gene expression profiles of the enzyme were investigated by the bioexpress database (genelogic inc., gaithersburg, md, usa). the enzyme gene cloned from mouse lung mrna was transiently expressed in cos cells. antiserum to the esterase was prepared by immunizing rabbits, and immunostaining was done using histomouse-tm-max kit (invitorgen corp., carlsbad, ca, usa) according to the manufacturer's manual. binding stability of na inhibitors to the four viruses are shown in figure the enzyme that hydrolyzes cs- to laninamivir in rat lungs was identified as carboxyesterase. this esterase was shown to be expressed in epithelial cells of rat lung by in situ hybridization. the mouse homolog of the rat esterase was carboxylesterase (ces ). the mrna of the mouse ces was shown to be highly expressed in lung and liver by the gene expression profile, and ces was also found to contain signal sequences for retention in endoplasmic reticulum (er) and golgi at the c-terminus. the cloned ces gene and the ces gene lacking the signal sequence were exogenously expressed in the cos cells. the cs- -hydrolyzing activity associated with the cos cells expressing ces was recovered from the culture sup of the cos cells expressing ces lacking the retention signal sequence. localization of ces was immunohistologically confirmed inside the airway epithelium cells of mice, which are the target cells for influenza virus infection. the long acting property of intranasal administration of cs- in mice can be explained both by the long retention of laninamivir in the respiratory tract and by the stable binding of laninamivir to influenza virus na. again, stable binding of laninamivir to na of pandemic (h n ) virus was also observed similar to that of seasonal h n virus. the following are speculated as the mechanisms for the long-lasting characteristics of cs- in mice. we explain the mechanism by clarifying a cs- hydrolyzing enzyme and its localization inside cells. the hypothesis of the mechanism is presented in figure . briefly, hydrophilic laninamivir may not enter easily inside cells, whereas hydrophobic cs- may enter inside cells. ces with er ⁄ golgi retention signal hydrolyzes octanoate of cs- figure . difference of binding stabilities of various na inhibitors to influenza virus neuraminidases. the na substrate was added to the influenza virus-na inhibitor complex (oseltamivir carboxylate, n; zanamivir, h; peramivir, s; laninamivir, •; distilled water, ¤), and the na reaction was followed for minutes. the background (only the na substrate [d] ) is also shown. a part of data from. to generate the hydrophilic drug, laninamivir, and then it is trapped inside er ⁄ golgi because of its high hydrophilicity. the glycoprotein, na, which matures in er ⁄ golgi, meets laninamivir there and efficiently makes a stable complex with it. there are some questions that remain. how does cs- move from the cell membrane to er ⁄ golgi? is laninamivir indeed trapped inside er ⁄ golgi, and does it make a complex with na in mice? we are now making an attempt to clarify these concerns. in our study, we have explored the antiviral potential of two newly synthesized compounds to provide protection against the novel pandemic influenza virus h n ( ) strain. the compounds were reconstituted in dimethylsulphoxide (dmso), and so the initial studies began with cytotoxicity determination of solvent on uninfected and untreated madin-darby canine kidney (mdck) cells. on obtaining an upper limit for dmso, the compounds were tested for estimation of their maximum non-toxic dose to the mdck cells. thereafter, the effective dose of the compounds was evaluated and validated by a number of assays and gene expression profiling at both nucleic acid and protein level. we found that these newly synthesized compounds possess potent inhibitory activity towards the novel pandemic influenza h n ( ) virus. these findings are being evaluated in vivo for a better understanding of their inhibitory capabilities and also their effect on the host metabolism. this will be required in the course of development of new drugs for use in the prophylaxis and treatment against the influenza virus. the mdck cell line (from nccs, pune) was maintained in · dmem media (sigma, st. louis, mo, usa) supplemented with % fetal calf serum and antibiotics viz. unit ⁄ ml penicillin and lg ⁄ ml streptomycin at °c ⁄ % co . the synthesized compounds used in this study were kindly provided by the department of chemistry, university of delhi, delhi, india. the pandemic influenza h n ( ) virus was isolated and propagated in the allantoic cavities of embryonated chicken eggs during the pandemic period. the virus stocks were prepared and stored at ) °c. plaque assay was performed as previously described by hui et al., . briefly, ae · mdck cells ⁄ ml were seeded in six-well plates and maintained in dmem for hours at °c ⁄ %co . the monolayer of the cells was inoculated with serially diluted virus samples for minutes at °c ⁄ %co . subsequently, a mixture of agar overlay was added, and the plates were incubated at °c for days or until formation of plaques. the plaques were visualized after removal of the agar plug and staining with ae % crystal violet or neutral red solution. the virus titre was expressed as plaque forming unit (pfu) per milliliter. the in vitro cytotoxicity analysis was performed to determine the % cytotoxic concentration (cc ) of the compounds on mdck cells. the compounds were dissolved in dimethylsulfoxide (dmso), and so a prior cytotoxicity analysis was performed to determine the toxic concentration of dmso on the cells. various concentrations of compounds were mixed with dmem containing % fcs before addition to the preformed monolayer of mdck cells in -well plates. a series of suitable controls for in vitro cc determination was included in every plate, and the plates were incubated in the optimum environment for mdck cell culture. the cc of test compounds was analyzed by estimation of percentage cell viability of the compound-and mocktreated mdck cells by performing a colorimetric assay using tetrazolium salt -( , -dimethylthiazol- -yl)- , diphenyl tetrazolium bromide (mtt) at end-point of hours post-incubation. the assay was performed as described by mosman . briefly, mtt stock at a concentration of ae mg ⁄ ml was prepared in · pbs. the media was aspirated from the wells and ll of mtt dye from the stock was added to each well. following incubation at °c ⁄ % co for - hours, the dye was very carefully removed from the wells, and the cells were incubated with ll of stop solution (dmso) per well at °c ⁄ % co for hour. the absorbance of the supernatants from each well was measured at nm, and the percentage cell viability was calculated. madin-darby canine kidney cells were maintained overnight in a -well tissue culture plate at °c ⁄ % co . the cells were inoculated with various virus dilutions at °c ⁄ % co for minutes and observed for cytopathic effect (cpe). the media from the experimental wells were aspirated after - hours of infection and were subjected to plaque assay. the percentage cell viability was determined by performing mtt assay. the results of both these tests were used to assess tcid of the virus. the pre-formed monolayer of mdck cells was inoculated with the -fold dilution corresponding to tcid of the virus for hour at °c ⁄ co . the experimental setup included control wells for the cells, virus, and compound. meanwhile, the concentrated stocks of the synthesized compounds were diluted with dmem (with % fcs) to various concentrations within their respective cc ranges. one hour post-infection, the cells were incubated with these diluted solutions. the cells were observed at various time intervals post-inoculation for cpe, and ll media was collected from each experimental well for performing hemagglutination test. after h, the media was collected for plaque assay and the cells were subjected to mtt cell viability assay. preformed monolayers of mdck cells were infected with virus and treated with the respective inhibitory concentration of the compounds. forty-eight to hours post-incubation, total cellular rna was isolated using ribozol (amresco, solon, oh, usa) and treated with lg ⁄ ml of dnase (promega, madison, usa). the concentration and quality of the rna from each well were determined by measuring their absorbance at and nm. one microgram of the cdna synthesized from each rna sample was used for sybr green-based real-time pcr detection of the ha gene of pandemic influenza h n ( ) virus. as a control, human glyceraldehyde- -phosphate dehydrogenase (hgapdh) was also amplified using gene specific primers. , immunoblotting immunoblotting was performed to further validate the antiviral potential of the compounds. the experimental protocol was the same as for real time rt-pcr analysis. the cells were harvested hours post-treatment with the compounds to prepare whole cell lysates in mammalian cell lysis buffer [ ae m nacl, ae m tris cl (ph ae ), ae m edta (ph ae ), m m protease inhibitor cocktail, lg ⁄ ml pmsf]. the protein concentration was determined by bca protein assay. the cell lysates were fractionated on % polyacrylamide for western blotting. the blot was developed using sheep monoclonal antibody (santa cruz biotechnology, ca, usa) against ha protein of influenza virus and horseradish peroxide conjugated rabbit-anti sheep igg ( : dilutions) as secondary antibody. the median cytotoxic concentration for compound meuh came out to be lm, and that for flh was lm. compounds showing potent antiviral effect on the pandemic influenza h n ( ) virus propagation in madindarby canine kidney cells ( figure ). the viral titres remained constant in cells treated with the compounds, while they increased in the untreated virus infected cells. ed for the compounds meuh and flh were and lm, respectively. fifty-two percent (meuh) and % (flh) inhibition against the pandemic influenza h n ( ) virus was achieved using ed of the test compounds. both the compounds were able to reduce the rna levels of the ha gene by approximately - %, whereas approximately % inhibition was seen when both the compounds were used in combination. similar results were obtained by the immunoblotting analysis ( figure ). antiviral therapy has shown to be a promising tool in the management of various respiratory diseases, including those caused by influenza viruses. we have already shown inhibition of influenza virus replication in our earlier studies using catalytic nucleic acids, which can be used as an approach in the development of new therapeutic strategy. these therapies are very useful as the influenza virus vaccines need annual renewals due to frequent genetic drifts in the viral surface proteins. in pandemic situations the existing vaccines do not provide complete protection against the novel virus as the population generally remains naïve for the newly mutated surface antigens. the antiviral drugs play an important role in the control of novel viral strains for which there are no vaccines available. however, the key obstruction in the extensive use of antiviral drugs is their cost and relative therapeutic efficacy provided. two classes of drugs were being used for treatment and control of the influenza virus infection in humans, the m ionchannel blockers , (amantadine and rimantadine), which prevent viral uncoating, and the neuraminidase inhibitors , (zanamivir and oseltmivir), which prevent the release of influenza virions from the cytoplasmic membrane. but widespread resistance to these antiviral drugs , has limited their use. thus, novel drugs are required for the effective therapy against the emerging strains of influenza virus. the novel chemical compounds used in our study were tested for their antiviral efficacy against the pandemic influenza h n ( ) virus. a reduction in the cpe in compound treated virus infected mdck cells indicated presence of antiviral activity in chemical compounds. the persistence of constant viral titers in the compound treated cells provided evidence for the interference posed by the compounds in the replication of influenza virus. inhibition in the ha gene expression further validated our hypothesis for the antiviral effect of compounds. the efficacy of these compounds in animal models is currently being validated in our laboratory. further, molecular studies are required to ameliorate the awareness regarding the mode of action of these chemical compounds against the viruses. and is now licensed in japan, while another, laninamivir, is being developed as an inhaled prodrug. resistance to nais among circulating influenza viruses was previously low (< % worldwide). [ ] [ ] [ ] however, the - influenza season was marked by a worldwide emergence of oseltamivir-resistant seasonal influenza a (h n ) viruses with the h y (h y in n numbering) in the na. [ ] [ ] [ ] [ ] [ ] [ ] the prevalence of oseltamivir resistance was even higher in the subsequent - influenza season with many countries reporting up to % oseltamivir resistance, seasonal and pandemic influenza viruses collected globally between october , and september , were submitted to the who collaborating center for surveillance, epidemiology and control of influenza at the centers for disease control and prevention (cdc) in atlanta, ga, usa, and propagated in madin-darby canine kidney (mdck) cells (atcc, manassas, va, usa). reference viruses representative of oseltamivir-sensitive and -resistant seasonal and pandemic viruses were also propagated in mdck cells. susceptibilities of virus isolates to the nais oseltamivir carboxylate (hoffman-la roche, basel, switzerland) and zanamivir (glaxosmithkline, uxbridge, uk) were assessed in the chemiluminescent ni assay using the na-star tm kit (applied biosystems, foster city, ca, usa) as previously described. additionally, subsets of virus isolates were tested for susceptibility to peramivir (biocryst pharmaceuticals, birmingham, al, usa). fifty percent inhibitory concentration (ic ) values were calculated using jaspr curve fitting software, an in-house program developed at cdc. curve fitting in jaspr was done using the equation: v = vmax · ( ) ([i] ⁄ (ki + [i]))), where vmax is the maximum rate of metabolism, [i] is the inhibitor concentration, v is the response being inhibited, and ki is the ic for the inhibition curve. box-and-whisker plot analyses of log-transformed ic s were performed for each virus type ⁄ subtype and nai using sas . software (sas institute, cary, nc, usa) to identify viruses with extreme ic values (outliers). outliers were characterized based on a statistical cutoff of ic greater than three interquartile ranges from the th percentile. outliers were subjected to genetic analysis by pyrosequencing and ⁄ or conventional sequencing to detect known or novel markers of nai resistance. those harboring previously characterized mutations in the na associated with nai resistance were considered drug-resistant; their descriptive statistics were determined separately from naisusceptible viruses. descriptive statistics to compute the mean, median, and standard deviation (sd), and a one-way analysis of variance were performed on original scale ic data, using sas . software (sas institute) for each nai and virus among seasonal influenza a (h n ) viruses tested for oseltamivir susceptibility (n = ), ( ae %) were outliers for the drug (table ) and harbored the oseltamivir-resistance conferring h y mutation in the na. by contrast, only a small proportion ( ae %) of tested h n pdm viruses (n = ) were resistant to oseltamivir. all influenza a (h n ) viruses (n = ) were sensitive to oseltamivir except for one outlier, a ⁄ ontario ⁄ rv ⁄ with d v mutation in the na, whose ic of ae nm was beyond the statistical cut-value off and > -fold the mean ic for the drug ( ae nm). all influenza b viruses (n = ) were sensitive to oseltamivir with exception of an outlier b ⁄ texas ⁄ ⁄ , with d e (d e in n numbering) mutation in the na, whose ic was beyond the cut-off, but only fourfold greater than the mean ic for the drug. all virus types ⁄ subtypes tested for zanamivir were sensitive to the drug (table ) , except for some outliers among seasonal influenza a (h n ) and a (h n ) outliers. the seasonal influenza a (h n ) outliers included a ⁄ thailand ⁄ ⁄ (h n ) and a ⁄ hawaii ⁄ ⁄ (h n ), both with combined h y and d d ⁄ g mutations in their na. the presence of concurrent mutations at na residues h and d in seasonal influenza a (h n ) virus isolates substantially enhances resistance to oseltamivir and peramivir and ⁄ or zanamivir, however, the changes at d are typically cell-derived and not present in clinical specimens. influenza a (h n ) outliers for zanamivir included a ⁄ ontario ⁄ rv ⁄ with d v mutation in the na, as well as a ⁄ maryland ⁄ ⁄ and a ⁄ vladivostok ⁄ ⁄ with d g and mixed d d ⁄ g mutations, respectively. some mild outliers for zanamivir among a (h n ) viruses with ic beyond the statistical cutoff but < -fold mean ic for the drug were also identified; their genetic analysis revealed presence of wildtype and mutant sequences at residue namely, d d ⁄ g, d d ⁄ n, or d d ⁄ a. mutations at residue d of the na are associated with reduced susceptibility to zanamivir in a (h n ) viruses, but were reported to be cell-culture derived in recent h n viruses. all virus isolates tested for peramivir (n = ) were sensitive to the drug, except for h y variants among seasonal influenza a (h n ) and h n pdm viruses, which exhibited reduced susceptibility to the drug. in addition, one influenza a (h n ) isolate, a ⁄ ontario ⁄ rv ⁄ with d v mutation in the na, showed reduced susceptibility to peramivir. the ic values determined in functional ni assays provide valuable information for detection of resistant viruses, but should not be used to draw direct correlations with drug concentrations needed to inhibit virus replication in the infected human host, as clinical data to support such inferences are inadequate. nevertheless, combining elevated ic values with the presence of established molecular markers of resistance in the na of virus isolates and their matching clinical specimens provides a reliable and reasonably comprehensive approach of identifying nai-resistant isolates for surveillance purposes. in this study, outliers with elevated ic values for oseltamivir among seasonal influenza a (h n ) and h n pdm viruses were confirmed to be oseltamivir-resistant based on the presence of the h y mutation in the na. outliers for oseltamivir and ⁄ or zanamivir among influenza a (h n ) viruses in this study were shown to harbor mutations at d , which were earlier associated with reduced susceptibility to zanamivir, and were cell-culture derived. the effects of d mutations on nai susceptibility appear to be strain-specific; however, there are no conclusive supporting data and further investigations are required. outliers among the influenza a viruses in this study exhibited changes in the na, derived naturally or through cell-culture, which altered their susceptibility to nais. however, mild outliers for oseltamivir and ⁄ or zanamivir among influenza a viruses with slightly elevated ic s, but without apparent changes in the na are sometimes identified. in such instances it is imperative to exclude the potential presence of influenza b among such outliers, using conclusive genetic tests such as real time pcr, since influenza b viruses exhibit higher ic values for oseltamivir and zanamivir than influenza a viruses. viruses exhibiting such mixes are typically excluded from statistical analyses of ic s for respective drugs and virus type ⁄ subtype. establishment of a clinically relevant ic cutoff value which could be used to differentiate statistical outliers from truly resistant viruses is imperative. global surveillance for nai susceptibility of influenza viruses circulating globally should be sustained to reflect the impact of seasonal and pandemic of influenza, given the limited pharmaceutical options available for control of influenza infections. nasopharyngeal swab specimens from patients with acute respiratory infection were collected at influenza sentinel surveillance units (outpatient and hospital-based) all over mongolia. specimens were transported to the virology laboratory, nccd, ulaanbaatar, and rt-rt pcr positive samples were grown in a mdck cell culture according to the protocol developed by cdc. and influenza virus gene segment (m genes) sequencing ( strains-genbank accession numbers: cy , cy , cy , cy , cy , cy , and cy ) and influenza virus gene segment (na gene) sequencing ( strains genbank accession numbers: cy and cy ) by the standard methods with applied biosystems xl genetic analyzer using primers supplied by who collaboration centers. a chemiluminescent na inhibition assay was performed with veritas microplate luminometer using the commercially available kit, na-star (applied biosystems, foster city, ca, usa), according to the manufacturers protocol. the na inhibitor susceptibility of influenza virus isolates was expressed at the concentration of na inhibitor needed to reduce na enzyme activity by % (ic ). oseltamivir carboxylate, was provided by f. hoffman-la roche ltd (basel, switzerland). na inhibition assay data were analyzed using robosage software comparing test data with the data produced by the reference na inhibitor sensitive and resistance strains, which were provided by the who influenza collaboration center, melbourne, australia. all viruses tested were sensitive to oseltamivir with two exceptions: a seasonal influenza virus a ⁄ ulaanbaatar ⁄ ⁄ (h n ) with ae nm ic value and a pandemic influenza virus a ⁄ dundgovi ⁄ ⁄ (h n ) with ae nm ic value ( figure ). there was oseltamivir resistance detected in ae % ( ⁄ ) of seasonal a (h n ) and in ae % ( ⁄ ) of a (h n ) pdm viruses. the oseltamivirresistant viruses were collected from untreated patients. in total, influenza b viruses were analyzed by na inhibition assay and all were sensitive to oseltamivir. the na of both oseltamivir-resistant strains contained h y mutation based on the sequencing analysis. the difference in the na amino-acid sequences between the mongolian oseltamivir-resistant viruses and the respective oseltamivir-sensitive reference viruses is shown in table all a(h n ) viruses analyzed for m channel inhibitor resistance by pyrosequencing contained the s n mutation and, thus, were resistant to this class of anti-influenza drugs. the segment sequencing revealed that seasonal a(h n ) viruses possess the common s n mutation. of note, a single strain a ⁄ zavkhan ⁄ ⁄ (h n ) contained an unusual s d change in the m protein. our study shows that the same prevalence [ ae % ( ⁄ )] of seasonal a(h n ) viruses with h y mutation in ⁄ season in mongolia with the published data for ⁄ season from japan. , however the prevalence of oseltamivir resistance in japan has dramatically increased in ⁄ season to % ( ⁄ ). the observed double mutations: h y and d g in a ⁄ ulaanbaatar ⁄ ⁄ (h n ) strain, which have been also found in japan in ⁄ season. the patient from whom the oseltamivir resistant seasonal influenza h n virus has been isolated was a -year-old boy, living in ulaanbaatar, the capital city, without history of using oseltamivir. the patient from whom the oseltamivir resistant a(h n )pdm virus was isolated was a year-old man, residing in the dundgovi, the southern province, also without history of antiviral treatment. according to the who data, isolation of the pandemic viruses carrying h y change from untreated patients has been uncommon. circulation of amantadine-resistant seasonal a (h n ) viruses has been increasing in mongolia since ⁄ influenza season. all pandemic influenza a(h n ) strains ( ) tested were resistant to m channel inhibitors due to the presence of the s n mutation in the m protein. among seasonal a(h n ) viruses, one contained a s d change whereas the others had s n, the well established marker of resistance to both amantadine and rimantadine. this is the first report of detecting the s d change in the seasonal a(h n ) viruses. according to the cdc data (unpublished), the s d change conferred the drug resistance in the a(h n ) viruses according to the virus yield reduction assay. it is essential to continue the antiviral resistance surveillance of influenza virus strains circulating in mongolia to ensure the efficiency of a proper clinical management of influenza patients. (conferred by the s n mutation). of note, the genotype and genotype dual resistant viruses from asia appear to be genetically similar to those previously reported dual resistant viruses from hong kong, sar. , the genotype virus was the only dual resistant virus with a nearly complete c genome. oseltamivir-resistance for this virus appears to be the result of a reassortment as demonstrated by the presence of the oseltamivir-resistant clade b na gene. although the detection of dual resistant seasonal influenza a (h n ) viruses is still rare, there has been an increased prevalence of dual resistance viruses during the last three seasons: . % ( of tested in - ), . % ( of in - ) , and % ( of in - ) (v p < . ). while the continued circulation or co-circulation of seasonal a (h n ) viruses is uncertain, the emergence of dual resistant influenza viruses in five countries does present a public health concern, especially since dual resistant viruses would limit the options for antiviral treatment to a single licensed antiviral drug: zanamivir. moreover, the markers of resistance seen in seasonal a (h n ) viruses also confer resistance in the more widely circulating pandemic a (h n ) virus. and, since the acquisition of mutations in influenza a viruses typically occur through drug selection, spontaneous mutation, or genetic reassortment with another drug resistant influenza a viruses, the detection of influenza a (h n ) viruses that are resistant to both adamantanes and oseltamivir warrants close monitoring, even if only detected at low frequency. new antiviral agents and strategies for antiviral therapy are likely to be necessary in the future. heightening concern that drug resistance will likewise become prominent in pandemic viral strains and highlighting the need for antiviral drug resistance surveillance. the h y mutation in h n neuraminidase is the most common mutation conferring resistance. however, due to the high mutation rates of viruses, new mutations can be expected that will also render viral neuraminidase less sensitive to antiviral drugs. pcr methods can be used to detect previously identified mutations; however, functional neuraminidase enzyme activity inhibition testing is necessary for detecting drug resistance that results from novel mutations. the two neuraminidase enzyme inhibition assays using either the fluorescent munana or chemiluminescent na-star Ò substrate are robust tools for ni susceptibility testing. the munan-a-based assay is broadly used by many groups, including many regional health organizations for ni susceptibility testing, yet no standardized protocol or dedicated kit has been in place for this assay, making comparison of data generated between different laboratories difficult. borrowing from multiple neuraminidase inhibitor susceptibility network (nisn)-published munana-based neuraminidase assay protocols, we have developed a kit-based fluorescent neuraminidase assay that offers both standardization and off-the-shelf quality-controlled reagents for ni susceptibility testing and other neuraminidase assay applications. the na-fluor tm influenza neuraminidase assay reagents and protocols were optimized in comparison to published nisn protocols according to the criteria of assay performance, ease-of-use, consideration of historically used assay conditions, reagent storage stability, and environmental impact. our optimized assay conditions consists of lm munana, ae mm mes, mm cacl , and ph ae in a ll assay volume, and performing the assay for minutes at °c following a minutes preincubation of drug with the virus. these conditions are consistent with the majority of published influenza ni screening data in publication. the standard na-fluor tm assay workflow for screening viral isolates for sensitivity to nis includes first titering the viral sample by neuraminidase activity to determine optimal virus concentration to be used in subsequent ic determination assays. the na-fluor tm assay is an ideal tool for titering virus based on neuraminidase activity in the viral coat. titering of viral samples prior to running the ic determination assays insured that assays would be performed within the fluorescence detection dynamic range of both the assay and the fluorometric instrument being used. viral titers giving rfus in the range of - were used for subsequent assays. comparison to traditional munana assays a primary goal of developing a standardized munana assay was to provide a standardized protocol and set of reagents that would allow for comparison of ni surveillance data between laboratories and over time. in addition, the assay should provide data comparable to historical data sets based on traditional munana-based protocols. to insure that our newly developed na-fluor tm assay met these criteria we performed side-by-side comparisons of the na-fluor tm assay to munana-based nisn protocols, as well as our na-xtd tm and na-star Ò chemiluminescent neuraminidase assays to compare assay sensitivity and dynamic range and for ni ic determination with multiple viral isolates. for all assay comparisons, assays were performed according to respective published protocols. for direct comparison of results, an equivalent amount of virus (and concomitant neuraminidase activity) was used for each assay. the na-fluor tm assay provides low-end sensitivity (by signal to noise ratio) and dynamic range similar to nisnpublished, munana-based protocols (data not shown). these assays all show a low-end detection of approximately ae u ⁄ well and dynamic range of - orders of magnitude when performed simultaneously side-by-side using serial dilutions of bacterial (clostridium perfringes) neuraminidase. these assays show approximately onefold less dynamic range and approximately fivefold less low-end sensitivity than chemiluminescent assays under these conditions. given the large amount of archived ni inhibition data for viral isolates over the past decade, it is very important for a standardized assay to generate data similar to established protocols so that data can be compared in relative terms. when run side-by-side, na-fluor tm assay provided oseltamivir carboxylate and zanamivir ic values similar to nisn-published, munana-based protocols. ic values vary somewhat for munana assays versus chemiluminescent assays depending on the viral isolate, as previously described. the na-fluor tm assay also exhibited similar sensitivity for detecting ni sensitive virus compared to nisn-published fluorescent assays as shown in figure . the large shift in ic values between oseltamivir-sensitive and resistant virus using the na-fluor tm assay enables detection of mutant virus in mixed viral samples ( figure ). this capability is critical for identifying resistant virus in clinical isolates presenting mixed populations of resistant and sensitive virus during ni susceptibility surveillance. several characteristics of the na-fluor tm assay make it an ideal assay for processing large numbers of viral isolates for ni sensitivity surveillance or for using the assay for high throughput screening for lead discovery of new antiviral reagents. the na-fluor tm assay signal was found to remain stable for up to hours after stop solution addition when stored at room temperature and for several days when stored at °c (data not shown). ic values did not change over these times, indicating that the assay is compatible with processing many samples in a short time frame. the na-fluor tm assay was also found to be highly reproducible giving a z' of ae or above indicating that the assay can be used confidently to identify nis in high throughput screening mode. the assay can tolerate up to % dmso, a common compound delivery reagent used in high throughput screens (data not shown). we have developed a standardized na-fluor tm assay suggested protocol that gives data similar to established mun-ana protocols. however, we have also found that several protocol adaptations can be made that generate comparable data while allowing the user more flexibility in assay mode, use of additional reagents, and to meet user-specified assay time requirements. the na-fluor tm assay can be run in either the standard minutes ⁄ °c endpoint mode described above or as real-time kinetic assay with repeated reads taken over time without the addition of stop solution, which both serves to terminate neuraminidase activity and to enhance the fluorescence of the product. for typical ni-sensitive viral strains, the rate of munana substrate turnover at °c is linear for at least hours (data not shown). as would be expected, rates of substrate turnover decrease in the presence of nis reflected in a decreased slope exhibited by real-time kinetic reads. real-time acquired rfus are typically - fold lower than rfus acquired after addition of stop solution at the same time point. ic values obtained using slope analysis for real-time assays are similar to values obtained by endpoint analysis. whether run in real-time or end-point mode, the linear rate of substrate turnover allows the user to run the assay for shorter or longer assay times than the standard protocol without compromise to assay performance. the na-fluor tm assay is also compatible with standard methods used in many laboratories to inactivate virus. we have shown that ni ic values for multiple viral strains remain unchanged when the assay is performed in the presence of ae % np- or % triton x- (data not shown). similar results are also obtained by adjusting the na-fluor tm stop solution to % ethanol prior to addition for assay termination. the assay is unaffected by phenol red concentrations present in cell culture media. we have developed a standardized munana-based fluorescent neuraminidase assay, the na-fluor tm influenza neuraminidase assay kit, which has been optimized for ni susceptibility screening. the assay provides data that can be compared to data generated using traditional munanabased protocols. the assay is economical, highly reproducible, easy to use, and environmentally friendly. the assay is flexible and amendable to user-specific adaptations including assay mode, assay timing, and reagent compatibility. trademarks ⁄ licensing ª life technologies corporation. all rights reserved. relenza is a registered trademark of glaxo- to test the prophylactic potency of h -vhhb, mice were treated intranasally with pbs, lg of h -vhhb, or negative control rsv-vhhb at , , or hours before infection with one ld of nibrg- ma virus. body weight loss was monitored daily, and on day mice were sacrificed to determine the viral load in the lungs. all mice that received h -vhhb retained their original body weight, whereas those receiving pbs or rsv-vhhb gradually lost weight (data not shown). intranasal administration of h -vhhb at or hours before challenge resulted in undetectable lung virus titers. when animals were treated with h -vhhb hours before challenge, virus titers were fold lower compared to pbs and rsv-vhhb treated mice, and three out of seven animals still had undetectable virus titers ( figure ). we next determined if h -vhhb nanobody Ò could be also be used therapeutically. we administered lg of this nanobody Ò intranasally to mice up to hours after chal-lenge with ld of nibrg- ma virus. four days after challenge, animals that received h -vhhb , , or hours after challenge had significantly higher body weight (data not shown) and lower lung virus loads than control mice. although mice treated with h -vhhb nanobody Ò hours after challenge were not clinically protected compared to control mice, they had significantly lower lung virus titers (figure ). to identify the ha amino acid residues that are potentially involved in h -vhh binding, escape viruses were selected by growth and plaque purification of nibrg- ma virus in the presence of h -vhhm or h -vhhb nanobodies Ò . the ha sequences of six independently isolated h -vhhm escape viruses revealed substitution of a lysine by a glutamic acid residue at position in ha (h numbering). in addition, two h -vhhm escape mutants carried an n d and four carried an n s substitution. the three-dimensional structure of nibrg- ha shows that n d ⁄ s and k e are close to each other as part of the corresponding antigenic site b in h ha. , interestingly, the n d ⁄ s mutations remove an n-glycosylation site, which is surmised to have evolved in h n ha as a strategy to mask an antigenic site. escape viruses selected in the presence of h -vhhb carried k n (n = ) or k e (n = ) substitutions. these results indicate that residues in antigenic site b, at the top of ha and very close to the receptor binding domain (rbd), are essential for neutralization of the virus by h -vhhm ⁄ b nanobodies Ò (figure ). the virus titer was measured in lung homogenates prepared on day after challenge. the x axis refers to the time points in hours relative to the challenge (time = hours) when ha-specific nanobodies (h -vhhb), control nanobodies (rsv-vhhb) or pbs was administered to the mice. # below detection limit, n not determined [n = - mice per condition: p values < ae (*)]. here we demonstrated that prophylactic and therapeutic treatment with llama-derived immunoglobulin single variable domain fragments is effective to control infection with h n influenza virus in a mouse model. we demonstrate that pulmonary delivery is a highly effective route of administration to treat or prevent influenza virus infection. in addition, we demonstrate that a homobivalent h -vhhb has powerful h n -neutralizing activity in vivo. it is important to note that we used a mouse-adapted derivative of the non-highly pathogenic nibrg- virus in our challenge model. nevertheless, this virus induces severe morbidity and lethality in mice. compared to conventional neutralizing monoclonal antibodies, vhhs offer the advantage that they are easy to produce in escherichia coli, typically with high yield. in addition, their small size ( kda for a monovalent vhh) and high folding capacity allow the generation of oligovalent vhh derivatives. in vitro escape selection revealed that a k e substitution in ha abolished the neutralizing effect of h -vhhm ⁄ b. a lys or arg residue at this position is conserved in all human h n virus isolates. of note, all selected escape mutants contained a glutamic acid or serine residue at position , which suggests that the conserved positively charged amino acid is important for neutralization by h -vhh nanobodies Ò . interestingly, escape mutants selected with h -vhhm also carried an n d ⁄ s co-mutation that removes an n-glycosylation site in this antigenic site of ha. the predicted n-glycosylation site at n in a ⁄ hong kong ⁄ ⁄ ha was shown to be glycosylated and may have evolved to mask an antigenic site near the rbd. , the selected amino acid changes are located near the receptor binding site of ha. therefore, it is possible that enhanced receptor binding properties of these escape viruses contribute to or are responsible for the loss of neutralizing activity of h -vhh nanobodies Ò . , we conclude that influenza virus neutralizing nanobodies Ò have considerable potential for the treatment of h n virus infections. although we focused on vhhs that presumably recognizes an epitope near the rbd, it is possible to select vhh molecules that bind to other epitopes in ha, including more conserved domains. more, a novel na (i m) substitution was discovered in a series of specimens from a patient. for the amantadine resistance, samples were tested, and all of them were confirmed to be resistant. we collected respiratory specimens from patients who had been clinically refractory to antiviral treatment since october upon ethical approval from the relevant institutions. to investigate the resistant pattern, sequence analysis to the na and matrix (m ) genes were conducted by reverse transcription (rt)-pcr and sequencing reaction. the obtained sequences were analyzed by the influenza sequences and epitopes database, which was developed in korea. eleven patients were found to be having oseltamivir-resistant pandemic (h n ) viruses with the h y substitution in the viral na genes (tables and ). some cases were associated with oseltamivir treatment on the basis of h y change from the oseltamivir-sensitive genotypes to oseltamivir-resistant genotypes in consecutive samples from the same patient. furthermore, a novel na (i m) substitution that may be associated with oseltamivir resistance was detected in specimens from one patient (patient g) who had myelodysplasia and received oseltamivir and peramivir (tables and ). in addition, we obtained viruses from clinical specimens (patients a and c) and evaluated antiviral susceptibility by measuring the dose of oseltamivir and zanamivir required for % inhibition (ic ) of na activity. these viruses (from patients a and c) were resistant only to oseltamivir (ic ae and ae nmol ⁄ l, respectively). susceptibility to zanamivir was not altered whether na contained y or h (ic ae and ae nmol ⁄ l, respectively). one isolate of pandemic (h n ) virus with an oseltamivir-sensitive genotype (h in its na) was susceptible to oseltamivir (ic ae nmol ⁄ l) and zanamivir (ic ae nmol ⁄ l). patients with oseltamivir-resistant pandemic (h n ) were treated during hospitalization with oseltamivir alone or with a combination of other antiviral drugs ( we found patients of oseltamivir resistance with h y mutation in the na gene of pandemic (h n ) virus through the surveillance of patient refractory to antiviral treatment. in addition, novel amino acid change (i to m) at position in the na gene, which might influence oseltamivir susceptibility, was detected in sequential specimens of a patient. these data showed that generation of oseltamivir resistance could be associated with oseltamivir treatment. therefore, it needs to strengthen the antiviral monitoring by supplementation of the clinical data including antiviral treatment. during the pandemic, oral oseltamivir was the primary antiviral medication used for treatment of hospitalized patients with ph n infection. many physicians worried that clinical deterioration or failure to respond to treatment with oseltamivir was due to either oseltamivir resistance or oseltamivir failure. in the united states, two investigational intravenous (iv) nais were available during - : peramivir through emergency use authorization and zanamivir by investigational new drug application. peramivir would be an option for patients with oseltamivir failure, but would not be appropriate for patients infected with h y oseltamivir resistant mutants. iv zanamivir was available in limited supply, but would be appropriate for severely ill patients infected with an oseltamivir-resistant ph n virus. during the pandemic, clinicians had few options for antiviral resistance testing in the united states. to respond to this need, the us centers for disease control and prevention (cdc) offered antiviral resistance testing for patients suspected to have clinical failure due to oseltamivir resistance. we describe the methods that cdc used to prioritize patients for testing during the pandemic and to detect markers for oseltamivir resistance, as well as the results from this testing. to facilitate decisions on which patients to test, we developed testing algorithms that were shared with state labora-tories, epidemiologists, and the emergency operation center at cdc. we prioritized patients who might benefit the most from antiviral testing given the inherent delay in providing antiviral results, e.g. patients who might have prolonged ph n shedding. patients that were critically ill [intensive care unit (icu) admission] or patients with severe immunocompromising conditions with clinical evidence for oseltamivir treatment failure (persistent detection of virus and clinical unresponsiveness to the drug) were prioritized. in addition, we tested specimens from patients that failed oseltamivir chemoprophylaxis. standard forms with information regarding specimen and minimal clinical information were collected on all patients. all protocols were validated and approved by clinical laboratory improvement amendments, e.g. quality standards to ensure accuracy, reliability, and timeliness of patient test results. information collected on patients was deemed public health response, not research, at cdc. clinical specimens, confirmed as pandemic influenza a (h n ), were tested for the h y mutation in the na using pyrosequencing. results were returned to sender within - hours of specimen receipt. from october until july , a total of specimens from patients were submitted for testing. viruses from ( %) of patients had h y mutation in the na in at least one submitted specimen. clinical information was available for patients (table ) . most patients had received oseltamivir for treatment prior to obtaining the specimen sent for antiviral testing. four patients received oseltamivir for chemoprophylaxis, all were immunosuppressed, and all had the h y mutant; duration of chemoprophylaxis until ph n infection was detected varied ( - days). among the patients with an h y mutant who were treated with oseltamivir, the median time on oseltamivir prior to collection of specimen with h y mutation was days (range - days). three patients were part of a hospital cluster of oseltamivir-resistant virus infections and were infected with h y mutants prior to oseltamivir treatment. patients with immunocompromising conditions accounted for almost half of all patient specimens tested, but they accounted for the majority of oseltamivir-resistant ph n virus infections (table ) ; among individuals with severe immunocompromising conditions and clinical failure while on oseltamivir therapy, ( %) had the h y mutant detected. among the immunosuppressed patients with an oseltamivir-resistant virus, ( %) had hematologic malignancies reported. in contrast, among the subset of icu patients without immunocompromising conditions and clinical failure while on oseltamivir therapy, we found little resistance: ( ae %) of icu patients had oseltamivir resistance detected. during the pandemic, we were able to provide timely and useful information to clinicians regarding suspected cases of oseltamivir resistance. our testing algorithm limited the number of specimens to specimens from the highest risk patients that would benefit the most from antiviral treatment. such an approach allowed us to offer this service without compromising our public health duties. in addition, the information we collected on patients from this service complimented our data on the national surveillance for antiviral resistance. we also performed national antiviral resistance surveillance from april to july . overall, resistant ph n viruses were identified from april to july in the united states among tested samples, including specimens described above, surveillance specimens, and resistant viruses reported in the literature. further studies to understand risk factors for oseltamivir-resistant ph n infection in patients with severe immunocompromising conditions are needed. while efforts to provide antiviral testing technology and materials to state laboratories are ongoing, clinicians still have limited options for such testing. rapid and inexpensive assays that could be performed by clinical laboratories, especially those caring for immunosuppressed patients, would be useful to inform patient care. the applied biosystems Ò na-xtd tm influenza neuraminidase assay kit provides the next-generation na-xtd tm , -dioxetane chemiluminescent neuraminidase (na) substrate, together with all necessary assay reagents and microplates, to quantitate sensitivity of influenza virus isolates to neuraminidase inhibitors. like the na-star Ò influenza neuraminidase inhibitor resistance detection kit, the na-xtd tm influenza neuraminidase assay provides highly sensitive detection of influenza neuraminidase activity. in addition, the na-xtd tm assay provides extended-glow light emission that eliminates the need for reagent injection and enables signal measurement either immediately or up to several hours after assay completion. the na-xtd tm assay is also used to quantitate influenza na activity directly in cellbased virus cultures to monitor viral growth or inhibition. global monitoring of influenza strains for resistance to neuraminidase inhibitors (nis) is essential for understanding their efficacy for seasonal, pandemic, or avian influenza, and studying the epidemiology of viral strains and resistance mutations. functional neuraminidase inhibition assays enable detection of any resistance mutation, making them extremely important for global monitoring of virus sensitivity to nis. the first-generation chemiluminescent na-star Ò influenza neuraminidase inhibitor resistance detection kit has been widely used for virus ni sensitivity assays, - including identification of a ⁄ h n pandemic virus resistant to oseltamivir. , in addition, this assay has been used for identification of new ni compounds, ni characterization, studies of virus transmission, drug delivery, na quantitation of virus-like particles, and cell-based virus quantitation. neuraminidase assays performed with chemiluminescent , -dioxetane substrates, including na-star Ò and na-xtd tm substrates, typically provide -to- -fold higher sensitivity by signal-to-noise ratio than assays performed with the fluorescent munana substrate. in addition, chemiluminescent assays provide linear results over - order of magnitude of neuraminidase concentration compared to - orders of magnitude with the fluorescent assay. the high assay sensitivity achieved with chemiluminescent assays enables use of lower concentrations of viral stocks, and the wide assay range minimizes the need to pre-titer virus stocks prior to ic determination. chemiluminescent reactions result in conversion of chemical energy to light energy, as light emission. the na-xtd tm substrate is a , -dioxetane structure bearing a sialic acid cleavable group. to perform the na-xtd assay, virus dilutions (from cell culture supernatant) are pre-incubated in the presence of neuraminidase inhibitor. then na-xtd substrate is added and incubated for minutes for substrate cleavage to proceed. finally, light emission is triggered upon addition of na-xtd accelerator, which provides a ph shift and a proprietary polymeric enhancer, both required for efficient light emission. chemiluminescent assays are performed in solid white microplates, and light emission is measured in a luminometer. the na-xtd tm substrate has a single structural difference from the na-star Ò substrate that provides a much longer-lasting chemiluminescent signal, with a signal half-life of approximately hours (not shown), compared to $ minutes with the na-star assay, eliminating the need for luminometer instruments equipped with reagent injectors and enabling more convenient batch-mode processing of assay plates. the na-xtd tm assay kit also provides a new accelerator solution, containing a next-generation polymer enhancer, and a triton Ò x- -containing sample prep buffer providing enhanced na activity. read-time flexibility is demonstrated by determination of oseltamivir ic values using data collected over hours after addition of na-xtd tm accelerator. although signal intensity slowly decreases over time, the ic curves and values are identical at each time point, shown using influenza b ⁄ lee ⁄ ( figure ) . triton x- detergent at % has been shown to inactivate flu virus while increasing neuraminidase activity. the addition of na sample prep buffer (containing % triton x- ) to virus stocks (at ⁄ volume, achieving a final concentration of %) provides increase in na activity up to fourfold, but is not consistently observed, and seems to be most effective with more concentrated virus stocks. ic values are unaffected by the addition of triton x- to the virus stock prior to virus dilution (not shown), so the assay is compatible with known virus inactivation reagents. assay sensitivity and ic values determined with the na-xtd assay have been compared to those obtained with both the chemiluminescent na-star assay and the fluorescent na-fluor assay (not shown). the chemiluminescent assays provide -to -fold higher sensitivity by signal-to-noise ratio, depending on the virus strain, wider assay dynamic range, and better low-end detection limit than the fluorescent assay. the wide assay range with the chemiluminescent assays enables determination of ic values over a range of virus concentrations, eliminating the need to titer virus prior to performing ic determination assays. ic values obtained with the na-xtd assay are nearly identical to those obtained with the na-star assay, with both oseltamivir and zanamivir neuraminidase inhibitors, and tend to be slightly lower than ic values obtained with the fluorescent assay. viral na quantitation provides a convenient read-out to measure viral growth or inhibition, including inhibition in the presence of inhibitory compounds or antibodies, described as accelerated viral inhibition with na as readout assay (avina). bation in the presence of varying concentrations of oseltamivir carboxylate. samples of culture media were assayed hours later. quantitation of na activity with the na-xtd tm assay demonstrates inhibition of viral growth by oseltamivir carboxylate in cell culture ( figure ). different volumes of culture media were assayed with the na-xtd assay, either in the culture plate or in a separate assay plate (not shown). performing the assay using the entire well contents ( ll) reduces assay sensitivity due to the high concentration of phenol red. assaying a smaller volume of culture medium (either in culture plate or a separate assay plate) provides higher sensitivity, and enables temporal monitoring or use of remaining culture medium for other assays. the applied biosystems Ò na-xtd tm influenza neuraminidase assay kit is a next-generation chemiluminescent neuraminidase assay providing high assay sensitivity and ''glow'' light emission kinetics for improved ease-ofuse. the applied biosystems Ò na-fluor tm influenza neuraminidase assay kit, based on the fluorescent mun-ana substrate, has also been developed to complement the na-xtd tm and na-star Ò chemiluminescence assays, for users lacking luminometer instrumentation or choosing to use fluorescence assay detection. together these kits offer: • standardized reagents and protocols • choice of detection technology • simple instrumentation requirements • high sensitivity for use with low virus concentrations • compatibility with batch-mode processing and largescale assay throughput • broad specificity of influenza detection • flexibility in assay format • additional na assay applications -cell-based viral assays, screening for new nis, detection of na from other organisms functional neuraminidase inhibition assays enable detection of any resistance mutation and are extremely important in conjunction with sequence-based screening assays for global monitoring of virus isolates for ni resistance mutations, including known and new mutations. together, these assays provide highly sensitive, convenient and versatile assay systems with standardized assay reagents, and simple assay protocols for influenza researchers. over hospitalizations and deaths in the us annually are attributable to seasonal influenza, primarily in chronically ill persons and the elderly. - following the emergence of pandemic h n influenza, severe illnesses have also been observed in children and young healthy adults. the occurrences of staphylococcal and pneumococcal pneumonia complicating influenza pandemics are well described. [ ] [ ] [ ] although temporal associations of bacterial pneumonia and influenza circulation have been reported, there is little precise data on rates of bacterial complications of seasonal or pandemic influenza. the study of bacterial lung infection has been hampered by insensitive tests for invasive disease and the difficulty of interpreting routinely obtained sputum culture results. , procalcitonin (proct), the prohormone of calcitonin, can discriminate viral and bacterial infections. this -aminoacid precursor protein normally produced by neuroendocrine cells of the lungs and thyroid gland was first shown to be elevated in bacterial infections in patients with pulmonary injury and pneumonitis. stimuli of proct include tnf-a, endotoxin, and other bacterial products. several studies indicate that bacterial infections commonly induce hyperprocalcitonemia, but that viral infections, including h n , are associated with only minimal increases. , , of note, proct induction is attenuated by viral-induced interferon-c. a meta-analysis of studies comparing proct and crp as markers for bacterial infection found that proct was more sensitive and specific than crp for differentiating bacterial from other causes of inflammation. , therefore, we measured proct levels in patients with seasonal and pandemic influenza and compared results with conventional methods for bacterial diagnosis. adults ‡ years of age admitted to rochester general hospital (rgh) from november st to june th for two winter seasons ( - ) with an admitting diagnosis compatible with acute respiratory tract infection were recruited for the study. patients were screened within hours of admission, and those with prior antibiotic use, immunosupression, or pregnancy were excluded. subjects or their legal guardian provided written informed consent. the study was approved by the university of rochester and rgh research subjects review board. at enrollment demographic, clinical and laboratory information was collected. influenza testing included nosethroat swabs (nts) for rapid antigen, viral culture, and reverse transcription-polymerase chain reaction (rt-pcr) and serology. testing for bacterial pathogens included blood cultures, sputum for culture and gram stain, nts for mycoplasma pneumoniae and chlamydophila pneumoniae pcr, s. pneumoniae antigen testing, and pneumococcal serology. if patients were unable to expectorate, sputum was induced with normal saline and bronchodilators. specimens were considered adequate by the standard criteria of > neutrophils (pmns) and < epithelial cells per high power field. serum was collected at admission and hospital day for proct measurements. influenza infection was defined a positive result for any of the following tests: . cloned proteins were coated on eia plates at ug ⁄ ml in bicarbonate buffer. after overnight incubation, plates were washed and two-fold dilutions of serum were incubated overnight at room temperature. plates were washed and incubated with alkaline phosphatase conjugate for hours, followed by substrate. a greater than or equal to fourfold rise in titer was considered evidence of infection with s. pneumoniae. urinary antigen for s. pneumoniae samples were assayed for antigen using the binax now kit. (binax inc, scarborough, me, usa). the proct was measured using time resolved amplified cryptate emission technology (kryptor pct; brahms, henningsdorf, germany). functional sensitivity is ae ng ⁄ ml (normal levels are ae ± ae ng ⁄ ml). mycoplasma and chlamydia pcr real-time pcr targeting the p adhesion gene for m. pneumoniae and the ompa gene for c. pneumoniae was used to detect atypical bacteria. results fifty-one of ( ae %) illnesses evaluated tested positive for influenza virus. of these, were due to ''seasonal influenza'' ( influenza a ⁄ h n and influenza b), and were identified as ''pandemic influenza'' ( h n ). demographics of both groups were similar: mean ages ± and ± years, respectively, and equivalent sex and racial characteristics. other than a higher incidence of underlying lung disease in the seasonal group ( % versus %, p = ae ), pre-existing medical conditions including obesity were similar. symptoms, physical findings, and discharge diagnoses did not differ, and chest radiographs (cxr) showed infiltrates in % and % of seasonal and pandemic subjects, respectively. two pandemic and one seasonal influenza patient developed respiratory failure, and none died. overall, bacterial infections were diagnosed in ( %) subjects ( -seasonal and -pandemic), and none were bacteremic. bacterial infections included: -s. pneumoniae, -m. pneumoniae, -s. aureus, and -h. influenzae. all seasonal patients were diagnosed with asthma or bronchitis, whereas three pandemic patients had pneumonia. mean serum proct (ng ⁄ ml) levels in seasonal versus pandemic patients on admission and day were: ae ± ae versus ae ± ae and ae ± ae versus ae ± ae , respectively, and were not significantly different (table ) . several patients in the pandemic group had high proct levels, and there was a trend toward more pandemic patients having admission proct values ‡ ae ng ⁄ ml than seasonal subjects [ ( %) versus ( %), p = ae ] ( figure a , b). of the four patients with proc-t > ae ng ⁄ ml, two had dense infiltrates on cxr, one had a peripheral wbc of ⁄ ml with a threefold increase in s. pneumoniae antibody, and one developed respiratory failure associated with copd exacerbation. reliable sputum samples (within hours of antibiotics) were collected in only ( %) subjects. of these, proct was ‡ ae ng ⁄ ml in two with influenza alone and three associated with bacterial infection, and < ae ng ⁄ ml in with influenza alone and five associated with bacterial infection. in the with reliable sputa and accepting the conventional bacterial diagnosis, sensitivity of a proc-t ‡ ae ng ⁄ ml for bacterial infection was %, specificity %, positive predictive value %, and negative predictive value %. notably, one patient considered to have influenza alone (proct - ae ng ⁄ ml) had group a streptococcus and s. aureus in a contaminated sputum and bilateral infiltrates on cxr. three of five patients with bacterial infections and proct < ae ng ⁄ ml had a clinical diagnosis of bronchitis. mean proct values were significantly higher in patients with infiltrates versus those with atelectasis or no acute disease on cxr ( ae ± ae ng ⁄ ml versus ae ± ae ng ⁄ ml, p = ae ). combining patients with proct values ‡ ae ng ⁄ ml with those having positive bacterial tests, rates of bacterial infection associated with seasonal and pandemic influenza were % and %, respectively. notably, antibiotics were administered to % of subjects despite % having no acute disease on cxr. in our study, bacterial infections were diagnosed in approximately % of adults hospitalized with influenza with no significant difference in rates noted between seasonal and pandemic influenza infected subjects. previous reports of bacterial infection rates of - % with seasonal influenza are difficult to compare with recent studies of pandemic influenza, because the latter tended to focus on more severely ill patients. [ ] [ ] [ ] bacterial pneumonia has been suspected or diagnosed in - % of patients in intensive care associated with h n infection and up to % of patients who died. , despite aggressive pursuit of specimens for bacterial testing, diagnoses could be confirmed in only ( ae %) of patients using conventional methodology. given the difficulty in establishing a diagnosis of bacterial infection, elevated proct values may be helpful to identify patients at high risk for invasive disease. in a study of patients with severe h n or bacterial infection necessitating intensive care, a threshold proct level of ae ng ⁄ ml, demonstrated % sensitivity and % specificity for bacterial infection. among patients with h n associated pneumonia, many of whom had respiratory failure, a threshold proct value of ae ng ⁄ ml provided a sensitivity of % and specificity of % for bacterial infection. access to samples from lower airways in ventilated patients in these studies may have improved recovery of bacteria and account for the different results we observed. it should be noted that none of our patients were bacteremic, which is a very strong stimulus for proct release. proct levels have been used successfully to guide therapy in community acquired pneumonia, and our data showing high proct levels in patients with infiltrates on cxr suggests proct may be most useful for excluding invasive disease. , elevated proct levels were not observed in patients with purulent sputum and clear cxr. it is notable that a proct level of < ae ng ⁄ ml did not exclude patients with bacterial bronchitis since proct has been used to guide antibiotic therapy in copd exacerbations. while it could be argued that healthy patients with bacterial bronchitis do not require antibiotic treatment, physician behavior in our study indicates antibiotics are frequently prescribed. combining patients with proct values ‡ ae ng ⁄ ml and those with a positive bacterial test, approximately % in patients in our study had bacterial complications associated with influenza infection. efforts should be made to curtail antibiotic use in hemodynamically stable patients with clear cxrs. given physician discomfort regarding discontinuing antibiotics, proct measurements in combination with routine bacterial cultures should be useful tools to guide therapy. influenza, mrsa, cytokines: diagnosis, treatment, prevention -a possible strategy for outpatient care we started the antiviral treatment of influenza in humans using neuraminidase inhibitors on january , in a successful attempt to cure a -year-old patient. since then, we have used the inhalant antiviral drug zanamivir, and later (october , ) changed to the use of oseltamivir with systemic bioavailability for treating patients with influenza. after years of experience with antiviral treatment of outpatients, we highlight the importance of early diagnosis and early treatment. the necessity of an earliest possible diagnosis was confirmed in the pandemic of . large hospitals reported that patients with an h n ⁄ infection had to be treated with extracorporeal membrane oxygenation. we are convinced this is due to delayed recognition of infection in most cases. valuable time is lost when the patient with a sudden onset has to be brought to a hospital for emergency treatment. the point at which the patient goes to the doctor is decisive, and this problem of timing and the delivery of early treatment is not specific to germany. in our medical office, we assessed patients with suspected influenza (to date seasonal infections, and in , h n ⁄ ) through clinical diagnosis, and then proven by point of care rapid test (quickvue; quidel, san diego, ca, usa) followed by pcr. all of the patients undergo concomitant lab tests: leukopenia, serum iron level, and the humoral inflammation status [sum of the c-reactive protein (crp) and fibrinogen levels]. because of the constant threat of a bacterial superinfection, a bacterial swab and antibiogram is carried out on every patient. in all cases positive for influenza, oseltamivir was given immediately. nowadays it is important that a double infection with influenza and mrsa must be recognized immediately and treatment started at once with antivirals and, when appropriate, with a suitable antibiotic. we pay particular attention to an extremely low iron level (signum mali ominis). in addition we monitor oxygen saturation and the course of the humoral inflammation status every - hours for every of our outpatients. among our patients with seasonal influenza, we saw within hours, within hours, and within hours after disease onset. for pandemic influenza, it was patients within hours, within hours, and two within hours. for all patients, we measured crp < ae mg and fibrinogen < mg ⁄ dl ( hours), crp < mg and fibrinogen < mg ⁄ dl ( hours), and crp > mg and fibrinogen < mg ⁄ dl ( hours, only seasonal cases). antibiotics were necessary in cases, heparin and oxygen administration in cases. one hundred forty-eight patients had a superinfection following influenza. the most common strains were haemophilus parainfluenzae and staphylococcus aureus. the subsequent use of a suitable antibiotic was only necessary in % of the patients. in all cases diagnosed, treatment (including heparin and oxygen administration) and monitoring were conducted in our medical office. none of our patients (seasonal and pandemic) had to be admitted to hospital. the early decision of whether or not antiviral and antibacterial treatment is taking effect is the only way the threat of a cytokine storm can be averted. not only does the primary care physician have to be aware of the pathophysiology involved, but also the necessary diagnostic and therapeutic options have to be made available to him. the result will lead to a saving of both lives and healthcare costs. this applies both in epidemic as well as in pandemic times. today we know that influenza leaves behind a defenceless immune system, and that the proteases of s. aureus contribute to influenza associated pneumonia. mark von itzstein, who discovered neuraminidase inhibitors, emphasized the synergistic cooperation of viruses and bacteria (personal communication, ). mrsa and influenza viruses are posing problems worldwide. the case of a -year-old boy with h n ⁄ infection demonstrates how fatal developments can be prevented. due to his constantly recurring colds, we had already detected the mrsa colonization years earlier and had always worked on boosting his general health and resistance. both the patient and his family were included in dealing with the problem. the patient was, and is, always vaccinated early with a virosomal vaccine (baxter). during the oktoberfest in munich in september , when h n infections were increasingly occurring, we learned that our patient had come down with an extremely acute feverish illness. with the help of the rapid test, we diagnosed an h n ⁄ virus infection and started treatment with oseltamivir immediately. the humoral inflammation status, which had increased very rapidly to more than ae mg ⁄ dl within hours, was treated with the effective cotrimoxazol from the antibiogram. at the same time, the patient was heparinized. the following day the patient had no fever and was symptom-free. it was only through our early knowledge of what could develop pathophysiologically that we were in a position to make the right decision at the right time. every doctor treating outpatients can follow this procedure if he is familiar with the pathophysiology of the disease and has the available tests on hand: virus rapid test, additional laboratory parameters (leukopenia, iron), and the humoral inflammation status. the decisive factor, however, is the constant clinical alertness towards the course of every acute feverish cold with acute onset. the patient has to remain in the care of the attending physician, and the chosen treatment has to be administered and monitored. this means constant spo measurements and checking the humoral inflammation status every hours. if a clinical worsening occurs during monitoring, the treatment regime has to be changed immediately, which means the administration of an appropriate antibiotic. this outpatient care on the part of the doctor has to be available days a week so that no time will be lost. reports from the netherlands and denmark show that, with the help of this preventive strategy under the motto 'search and destroy,' the dangerous, fatal course of infections reported in germany with at least four deaths a day, can be avoided. however, the doctor has to be adequately remunerated for the elaborate amount of time this intensive outpatient care requires. with our strategy, we have moved from divergence to convergence in the care of our patients. we reported on our years of clinical experience with this approach at the antivirals congress in peking. our main message was early diagnosis and early treatment. we were able to demonstrate this in outpatients with seasonal influenza and h n ⁄ outpatients. our creed is: as much outpatient care as possible and as little hospitalization as possible. virological and autopsy findings in suspected and confirmed fatal cases of h n pandemic influenza in the czech republic -preliminary results influenza viruses cause substantial morbidity and mortality. pandemic influenza may have a serious impact on certain (mainly younger) age groups in comparison with seasonal flu. influenza is one of few viral infections capable of causing a pneumonia that is difficult to cure and ⁄ or leads to sudden death. the aim of this study was to analyze and compare virological and autopsy findings in patients who died with suspected or confirmed h n pandemic influenza virus infection. there were virologically confirmed cases of pandemic influenza and deaths in the czech republic during pandemic wave. more than influenza strains belonging to the new pandemic variant were isolated in the national influenza reference laboratory. postmortem biological samples were collected from any patient who died with suspected influenza infection to test for respiratory viruses. the samples were screened for h n pandemic influenza virus by real-time pcr (rt pcr), and when rt pcr positive, by virus isolation assay. no immunohistochemical staining for influenza antigen was done on the rna pcr positive cases. other important respiratory viruses such as respiratory syncytial virus, parainfluenza viruses, and adenoviruses were detected by virus isolation assay in a suitable cell culture. epidemiological analysis of postmortem histopathologic findings in the airway tissue was carried out in of fatal cases. virological findings were subsequently correlated with histological changes and available demographic and clinical data. statistical analysis was performed by t-test using spss software. sixty-one deaths ( males, females) were analyzed. the rna of the h n pandemic influenza virus was detected by pcr in cases, while cases remained negative. five respiratory syncytial viruses and two adenoviruses were detected in the influenza negative group. the mean age of confirmed h n pandemic influenza victims was ae years, age range - years and median ae years. the mean age of influenza negative victims was ae years, age range - years and median ae years. the % ci for the difference in the age between the two groups is ) ae ; ae . the test is statistically significant at the % level. the obtained significance (p = ae ) can be explained by the relatively small size of the study group. the most common postmortem histopathologic finding in the lung tissue of the h n pandemic influenza virus-positive victims was diffuse alveolar damage (often bilateral) and ⁄ or hyaline membrane formation, possibly with signs of respiratory distress syndrome (in , i.e., ae %, of autopsied patients). in the h n pandemic influenza virus negatives, the most common finding was pneumonia or bronchopneumonia with the detection of various bacterial species (in , i.e., ae % of autopsied patients). the cause might be either primary bacterial infection or superinfection following primary infection with influenza virus that remained undetected. the h n pandemic influenza victims were younger than the patients who died with suspected but undetected h n pandemic influenza. the majority of deaths were primarily linked to rapidly developing respiratory failure. this result supports the previous reports of severe respiratory outcomes in younger age groups that are typically linked to the spread of a pandemic strain of influenza. due to limited amount of pandemic vaccine, especially at the beginning of pandemic, it is advisable to assess experiences with antiviral treatment, mainly dosing, and way of antiviral administration. primers specific for each of the eight genes of pandemic h n ⁄ were adopted from assays as described previously to discriminate against seasonal human h n and h n viral segments (table ) . the primers were allowed to cross-react specifically with the sister clade viral segments of pandemic h n ⁄ . the method we employed in this study was a -step singleplex sybr green-based real-time rt-pcr. this approach helped lower the running cost of the assays and facilitated downstream molecular analyses (e.g., sequencing) by using screened cdna samples. viral rna was extracted from viral cultures or clinical samples as described , and was converted to cdna in a universal rt-pcr. each ll rt reaction containing ae ll of purified rna, ll of · firststrand buffer (invitrogen), u of superscript ii reverse transcriptase (invitrogen), ae lg of uni ( ¢-ag-caaaagcagg- ¢), ae mm of deoxynucleoside triphosphates and mm of dithiothreitol was incubated at °c for minutes, followed by °c for minutes for heat inactivation. for each segment-specific real-time pcr, the ll reaction contained ll of a -fold diluted cdna samples, ll of fast sybr green master mix (applied biosystems), and ae lm of the corresponding primer pair. the thermocycling conditions of all eight segment-specific pcrs were optimized as °c for seconds, followed by cycles of °c for seconds and °c for seconds, and all eight assays were performed simultaneously in a sequence detection system (applied biosystems). at the end of the amplification step, pcr products went through a melting curve analysis to determine the specificity of the assay ( - °c; temperature increment: ae °c ⁄ seconds). cdna of a ⁄ california ⁄ ⁄ virus was used as a positive control. robust and specific amplification was achieved in all eight segment-specific real-time rt-pcr reactions. pcr product for each segment of pandemic h n ⁄ yielded unique melting curve pattern with distinctive melting temperature (tm), which was not observed in negative and water controls ( figure ). reactions with tm value within sds of the mean tm were determined as positive. we evaluated the assays with a number of serologically confirmed human clinical samples. all pandemic h n ⁄ samples (n = ) were positive in all eight assays, while all seasonal samples (h n = ; h n = ) were negative in all assays, as expected ( figure and data not shown). these results showed that no reassortant of pandemic h n and seasonal viruses was present in the tested human isolates. we applied these assays to our on-going influenza virus surveillance program in swine. nasal and tracheal swab samples were collected at an abattoir in hong kong and cultured in madin darby canine kidney cells or embryonated eggs as described. positive viral cultures in hemagglutination assays were tested with the established segmentspecific real-time rt-pcr assays. among swine viral isolates collected from to september , of them were recognized as pandemic h n ⁄ in all eight segments. they were confirmed to be of pandemic h n ⁄ origin by subsequent full genome sequencing analyses, showing that there were interspecies transmissions of the virus from humans to pigs. , the remaining viruses had one to seven gene segments positive in the segment-specific real-time rt-pcrs. thirty of them were selected as representative samples for full genome sequencing analyses based on the genotyping data generated in our assays. they were swine h n or h n viruses with their gene segments derived from tr or eurasian avian-like swine lineages. it should be highlighted that all of their positive gene segments in our assays belonged to the sister groups of pandemic h n ⁄ . their melting curve patterns were very similar to those derived from segments of pandemic h n ⁄ , except for ha of tr lineage. our results successfully demonstrated the use of these segment-specific real-time rt-pcrs to recognize gene segments of contemporary tr (pb , pb , pa, ha, np, and ns) and ea (na and m) swine viruses. the ha-specific assay was able to discriminate pandemic h n ⁄ from other contemporary swine viruses in the same lineage. nevertheless, to confirm the identity and to examine all the genetic variations in the viruses of interest, full genome sequencing analyses were necessary. in this study, the biggest obstacles in primer design were sequence similarity and diversity of influenza viruses. we attempted to use degenerated primers, but they were highly non-specific. the finalized non-degenerated primers crossreacted with genes from pandemic h n ⁄ and its sister clade tr (pb , pb , pa, ha, np, and ns) and ea (na and m) swine viruses with some minor sequence mismatches. three avian (h n , h n , and h n ) and classical swine (h n ) were also tested with our assays. all of these animal viruses were negative, except for ns gene of the classical swine virus. our segment-specific real-time rt-pcr assays might be used in high throughput genotyping. they detected pandemic h n ⁄ viruses and acted as a preliminary screen-ing tool to select virus reassortants of interesting genotypes for further sequencing analyses. in fact, we identified a novel reassortant in january during the course of this study. this sw ⁄ hk ⁄ ⁄ has a previously unidentified viral gene combination as shown in figure . it was confirmed to be a reassortant between pandemic h n ⁄ and other swine viruses in full genome sequencing characterization. it has a pandemic h n -like n gene, an ea-like h , and the other six internal genes derived from tr swine viruses. , the eight established real-time rt-pcrs can rapidly reveal the gene-origins of influenza viruses. we are currently using these assays in influenza surveillance in humans and other animals. it is believed that similar strategy might be applied to detect and genotype other influenza viruses and possible reassortants in the future. pandemic influenza a ⁄ h n ⁄ infects millions of people around the world. a significant fraction of the world's population may also already have been exposed to the virus and, although asymptomatic, may be at least partially immune to the disease. a precise assessment of the number of people exposed to the influenza a ⁄ h n ⁄ virus is epidemiologically relevant. however, assays typically used to estimate antibody titers against a particular influenza strain, namely hi and neutralization, require use of the actual virus. this seriously limits broad implementation, particularly in regions where high biosafety facilities are unavailable. we developed an elisa method for the evaluation of presence of specific h n influenza virus-antibodies in serum samples. mouse anti-histidine tagged antibodies ( ll; lg ⁄ ml; abd serotec Ò , uk) in pbs (ph ae ) were dispensed into standard -well plates and incubated for - hour at room temperature. excess antibody was removed by at least two successive alternate washings with pbs-tween ae % and pbs. commercial blocking solution ( ll, superblock Ò t ; pierce Ò , usa) was added and incubated for at least hour at room temperature. after successive washing steps with pbs-tween ae %, non-glycosylated histidine-tagged recombinant protein ( ll; lg ⁄ ml) was added to each well. this protein consisted of the receptor-binding domain of the hemagglutinin of the influenza a ⁄ h n virus. , after hour incubation, wells were washed for at least two alternating minutes cycles with pbs-tween and pbs. a : dilution of the serum or plasma sample to be assayed ( ll) was added to each well and incubated at room temperature for hour. after repeated alternating minutes pbs-tween ae % and pbs washes, anti-human igg antibody solution ( ll ⁄ well; : dilution in pbs-tween ae %) marked with horse radish peroxidase (pierce Ò , usa) was added and incubated for hour at room temperature. after repeated alternate washes with pbs-tween ae % and pbs), substrate solution ( ll; -step ultra tmb-elisa; pierce Ò ) was added to each well. after incubation for minutes at room temperature in darkness, the enzymatic reaction was stopped by addition of m h so ( ll ⁄ well). yellow color produced by the enzymatic reaction was evaluated by absorbance at nm in a biotek Ò microplate reader (usa). blank assays using albumin in place of human sera established the elisa background signal, which was subtracted from sample absorbance signals: abs serum sample ¼ abs serum sample before correction À abs albumin sample : absorbance values were normalized based on the average signal of non-exposed subjects (uninfected subjects), and expressed as normalized absorbance (abs norm ): where abs serum ample is the sample absorbance signal, abs albumin sample is the albumin control absorbance signal, abs non exposed subjects is the average absorbance signal of non-exposed subject samples. for ferret serum samples, the same basic protocol was followed, with minor modifications. an anti-igg anti-ferret polyclonal antibody preparation was used at a dilution of : in pbs-tween ae %. a recombinant receptor-binding domain of the ha of the influenza a ⁄ h n ⁄ virus, expressed in escherichia coli strains, was used as the elisa antigen. this kda protein, designated here as ha - -rbd, contained amino acids - of the influenza a ⁄ mexico ⁄ indre ⁄ (h n ) hemagglutinin. a sequence coding for a series of six histidines at the n-terminus of the protein was included in the genetic construct to allow purification using immobilized metal affinity chromatography (imac) and attachment to assay surfaces treated with anti-histidine antibodies (or alternatively co + or ni + ). a panel of four samples (kindly provided by st. jude from ferrets exposed to different influenza strains, namely h n , h n swine, and h n , was also tested by the elisa method using : dilutions. protein ha - -rbd specifically and selectively recognizes antibodies from serum samples from convalescent h n ⁄ influenza subjects. dubois et al. demonstrated that this protein, produced in e. coli, folds properly into a -d structure practically indistinguishable from the analogous region in the ha of the influenza a ⁄ h n ⁄ virus. ha - -rbd preserves three of the conformational immunogenic epitopes (sa, sb, and cb) described for influenza a ⁄ h n hemagglutinins. the recombinant protein was used as the antigen, attached through histidine tags to microplate surfaces treated with anti-histidine antibodies to discriminate between serum samples from subjects exposed and non-exposed to influenza a ⁄ h n ⁄ . samples collected before the pandemic onset, and therefore presumed to exhibit low specific antibody titers against influenza a ⁄ h n ⁄ , were analyzed by elisa using the antigen ha - -rbd. the histogram of normalized absorbance values from this sample set displayed a normal behavior with a standard deviation of ae units. only ae , ae , and ae % of these samples exhibited normalized absorbance values higher than ae , ae , and ae , respectively. no sample from non-exposed individuals presented an absorbance value higher than ae . variability among samples from non-exposed subjects was much lower than in samples with high specific serum antibody titers from convalescent h n ⁄ patients. exposure to the h n ⁄ influenza virus with this elisa method can be predicted by absorbance values normalized to those of abs norm ¼ ðabs serum ample À abs albumin sample Þ=ðabs non exposed subjects À abs albumin sample Þ ð Þ serum from uninfected subjects. consequently, for reliable results, inclusion of samples from non-exposed subjects on every assay microplate is necessary. figure shows the analysis of human serum samples, including samples from convalescent patients with positive diagnosis by rt-pcr. three positive (dark gray bars) and two negative controls (light gray bars) were included in the same microplate. all serum samples corresponding to convalescent subjects exhibited absorbance values ae - ae times higher than negative samples ( figure ). normalized absorbance values above ae suggested exposure to the virus, although, a more conservative threshold value of ae units is proposed for discrimination between exposed and non-exposed subjects. the elisa method described here yields adequate reproducibility and a high signal ⁄ noise ratio within determinations in the same microplate and among different microplates. using a normalized absorbance value of ae , the method was able to discriminate samples from convalescent patients, preferably after the third week of infection, and at least up to the twentyfourth week of exposure. assay sensibility was further validated against results from hi assays. a previously reported study showed that all members in a pool of fourteen samples diagnosed as positive by hi exhibited normalized absorbance values higher than ae , and % of them exhibited normalized absorbance values higher than ae . in general, high hi titers (> ) were correlated with normalized absorbance values higher than ae . figure a shows results using the ha-rbd elisa method and the hi assay on a pool of seventeen known positive serum samples corresponding to convalescent h n ⁄ patients. all samples determined as positive by hi ( samples) were also positive by elisa. while sensitivity of the hi assay was ⁄ = ae %, the elisa method recognized all samples correctly as positive ( % sensitivity) when a threshold of ae or ae was used. figure b shows that sera from ferrets infected with other influenza strains (h n , h n swine, and h n ) showed no cross-reactivity when analyzed by elisa. in summary, the ha-rbd elisa method presented here consistently distinguished influenza a ⁄ h n ⁄ infected and non-infected individuals, particularly after the third week of infection ⁄ exposure. since no actual viral particles are required, this assay can be readily implemented in any basic laboratory. in addition, should sufficient vaccine be unavailable, this elisa could determine the level of specific antibodies against the virus and presumably the extent of partial protection in a subject. therefore, the elisa protocol might allow better administration of vaccination programs during pandemic or seasonal influenza outbreaks. in april , a novel h n influenza virus emerged in north america and caused the first influenza pandemic of the st century. [ ] [ ] [ ] [ ] the pandemic h n (pdmh n ) has a unique gene constellation that was not previously identified in any species or elsewhere. it is genetically related to the triple reassortant swine h n influenza viruses currently circulating in north america, with the exception of the neuraminidase (na) and matrix (m) genes, which are derived from a eurasian swine influenza virus. swine h n influenza viruses were first isolated in and continued to circulate in north america with very little antigenic changes (classical swine h n ) until . since , however, the antigenic make up of swine h viruses has shown increased diversity due to multiple reassortment events and the introduction of h n genes from human influenza viruses. currently, four swine h clusters (a, b, c, d) are found endemic in the north american swine population. , these swine h viruses show substantial antigenic drift compared to the classical swine h viruses. cluster d swine h is derived from current human h viruses, and there is a substantial antigenic divergence between classical swine h and human seasonal h viruses. epidemiological evidence shows a two-way transmission of influenza viruses between swine and humans, and such events lead to the emergence of the pdmh n virus. , , phylogenetic analysis have suggested that possible ancestors of the eight genes of pdmh n were circulating in the swine population for at least years prior to the emergence of the pdmh n virus in humans, although the pdmh n virus itself was not isolated from pigs until after the pandemic. interestingly, pdmh n infections have been reported not only in humans and pigs, but also in other animal species such as turkeys, cats, ferrets, cheetahs, and dogs. [ ] [ ] [ ] after the first report of pdmh n infection in swine in canada, other countries, including argentina, australia, singapore, northern ireland, finland, iceland, england, united states, japan, and china reported outbreaks of pdmh n in swine as well. , [ ] [ ] [ ] the ample geographic range of pdmh n outbreaks in swine, its apparent broad host range, and the possibility of two-way transmission between swine and humans poses a tremendous challenge for controlling the virus. therefore, to differentiate pdmh n from other h strains, particularly in swine and human populations, is an important issue to ascertain the magnitude of the disease caused by the pdmh n . in this study, we developed an elisa assay to discriminate pdmh n strains from other swine and human h viruses. madin-darby canine kidney (mdck) cells (atcc, manassas, va, usa) were maintained in modified eagle's medium (mem) containing % fbs. a ⁄ california ⁄ ⁄ ⁄ h n virus (ca ⁄ ) was kindly provided by the centers for disease control and prevention (cdc), atlanta, georgia. other viruses are listed in table . viruses were propagated in mdck cells and stored at ) °c until use. viruses were titrated by the reed and muench method to determine the median tissue culture infectious dose (tcid ). three monoclonal antibodies ( b , h , and f ) against ha of pandemic h n were prepared in our laboratory following previously described methods (shao and perez et al., unpublished). purification and labeling of mabs mab b , h and f were purified on a protein g-sepharose affinity column (upstate biotechnology, lake placid, ny, usa). biotinylation of the detection antibody in the elisa was performed using sulfo-nhs-lc-biotin (sulfosuccinimidyl- -(biotinamido)hexanoate; pierce, rockford, il, usa) according to the manufacturer's instructions. purified h and f were selected as the capture antibody, and biotin-conjugated b was selected as the detection antibody, and hrp-conjugated streptavidin (abcom, cambridge, ma, usa) was developed using the tmb substrate system (kpl, gaithersburg, md, usa). in brief, the mixture of the purified h and f ( ae and ae lg ⁄ ml respectively, in carbonate ⁄ bicarbonate buffer, ph ae ) was coated to -well plates (test well, t) for h at °c. at the same time, a control antibody was coated to -well plates (control well, c). after blocking the plates with % (w ⁄ v) non-fat milk in pbs for hour at °c, the samples were diluted in extract buffer ( %tween- , ae %bsa in pbs) and added to the wells ( ll ⁄ well, each sample was table . specificity assay of the sandwich elisa result (t ⁄ c) added to four wells-two for t wells and two for c wellsand the mixture was incubated at °c for hour. after four washes, ll biotin-conjugated b ( ae lg ⁄ ml) in dilution buffer ( ae % bsa in pbs) was added to the wells and the mixture was incubated for h at °c. following three washes, ll diluted hrp-conjugated streptavidin ( ae ng ⁄ ml) in dilution buffer was added to the plates. after incubation for h at °c, the plates were washed five times, and the binding developed using the tmb substrate system for minutes. the ratio of the average od value of the t wells to that of the c wells (t ⁄ c) of individual samples was calculated. t ⁄ c values > ae were considered positive in the sandwich elisa. we developed three monoclonal antibodies, b , h , and f , against a prototypical pdmh n strain, a ⁄ california ⁄ ⁄ (h n ) (ca ⁄ ). these monoclonals were used to develop a rapid sandwich elisa for specific diagnosis of pdmh n strains. purified h and f were used as capture antibodies, whereas the biotin-conjugated b was used as detection antibody. the sandwich elisa showed strong reaction with different pdmh n strains as described in in order to evaluate if the sandwich elisa could distinguish the pdmh n from other swine h clusters (a, b, c, d), swine influenza strains spanning these clusters were tested. these viruses were first diluted : in extract buffer, and then added to the coated plates. as shown in table , the t ⁄ c ratios of these viruses were < ae , and therefore showed negative elisa result. likewise, testing of human seasonal virus strains a ⁄ brisbane ⁄ ⁄ (h n ), a ⁄ malaya ⁄ ⁄ (h n ), a ⁄ wsn ⁄ (h n ), and a ⁄ brisbane ⁄ ⁄ (h n ) also showed negative elisa results. furthermore, the sandwich elisa showed no cross reaction with avian influenza viruses, including strains of the h , h , h , h , h , h , h , h , h , h , and h subtypes. more recently, the mutation d g in the ha of some pdmh n strains has been associated with exacerbated disease and altered receptor binding. [ ] [ ] [ ] [ ] [ ] to evaluate if such mutant could be detected in our sandwich elisa, we tested a mutant of a ⁄ netherland ⁄ ⁄ (h n ) carrying the d g mutation (engineered by reverse genetics). as described in table , our elisa could still capture the d g mutant virus and showed a positive reaction, which highlights the specificity of our assay for pdmh n strains, even those with mutations. to evaluate the sensitivity of the elisa, we used the serially diluted pdmh n viruses to determine the limit of detection (lod). as shown in table , in our elisa the highest positive dilutions of nl ⁄ and ca ⁄ were : and : , respectively. the lod of the sandwich elisa by tcid was ae · and ae · tcid ⁄ ml, for nl ⁄ and ca ⁄ , respectively. it is important to note that the t ⁄ c ratio from nl ⁄ and ca ⁄ viruses showed clearly a dose dependent effect, while the t ⁄ c ratio of a ⁄ swine ⁄ iowa ⁄ (h n ) did not show the same dependence and was always < ae , corroborating the high specificity of the sandwich elisa for pdmh n strains. although we did not compare our elisa with other current commercial rapid influenza detection kits, the lod of our elisa assay is similar to other commercial kits that detect human seasonal influenza virus. comparison of the sandwich elisa with the ''gold standard'' -virus isolation in order to further evaluate the feasibility of the application of the elisa to clinical samples, nasal wash samples ae · ^ )( ae ) )( ae ) )( ae ) )( ae ) )( ae ) )( ae ) )( ae ) )( ae ) -from ferrets, of those previously infected with ca ⁄ and shown positive by virus isolation, were tested. the samples were diluted : in extract buffer and then tested using the sandwich elisa. result showed out of positive samples by virus isolation were positive also by the sandwich elisa (sensitivity ae %). the samples tested that were negative by virus isolation were also negative in the elisa, indicating % specificity for our assay. these results show not only that our elisa has high compatibility with the virus culture method, but also indicates this application can be used for clinical samples. although real time rt-pcr targeting the ha gene has been used for specific diagnosis of pdmh n with high sensitivity, [ ] [ ] [ ] [ ] [ ] [ ] it is a method that requires manipulation of the sample to extract viral rna, and it is prone to crosscontamination during the pcr steps. in this study, we described a convenient sandwich elisa based on three mabs developed against the pdmh n strain. the elisa not only shows high specificity for pdmh n strain, but also shows great sensitivity. the elisa could distinguish pdmh n strains from human seasonal h and h viruses and, more importantly, from other swine h viruses. we must note that current rapid diagnostic tests cannot be used to differentiate pdmh n from swine or human h viruses. it is also worth noting that the sensitivity of commercial rapid antigen-based diagnostic tests for detecting pdmh n is lower than that for human seasonal influenza viruses. , a study by kok et al. showed that sensitivity of the current rapid antigenic tests for pdmh n is only ae %, whereas that for seasonal influenza a is ae %. chen et al. developed a dot-elisa and increased the sensitivity for influenza rapid antigen detection. however, the dot-elisa developed by chen cannot distinguish among subtypes. the lod of our elisa is between ae · to ae · tcid ⁄ ml, comparable to the lod of rapid diagnostic tests for human seasonal influenza viruses. compared to the ''gold standard''-virus isolation-our sandwich elisa showed ae % sensitivity using ferret nasal washes. our results highlight the potential application of our sandwich elisa for the specific diagnosis of pdmh n viruses. the timely and reliable laboratory evidences are vital factors for field epidemiologists trying to control outbreaks of infectious diseases and for the practicing clinicians to properly manage disease cases. therefore, analysis of new detection methods in comparison to the routine ''classical'' methods is essential to select new methods to be introduced into health service practices, especially in developing countries. in this study we have compared rt-rt-pcr detection of influenza viruses and direct fluorescent-antibody assay using r-mix hybrid cells (a &mv lu) with the ''classical'' cell culture methods in developing country settings. in this study, we analyzed nasopharyngeal swabs col- the detection of influenza h , h , b, and pandemic influenza (h )pdm virus-specific nucleic acids was performed by rt-rt-pcr in abi fast real time pcr system using primers recommended by cdc, usa, and super-scriptÔ iii one-step rt-pcr and platinum Ò taq dna polymerase kits (invitrogen). the cycling protocol was: minutes at °c, minutes at °c, and cycles of seconds at °c, seconds at °c. rapid detection of influenza infected cells has been performed by dfa using the infected hybrid cells of r-mix within hours after inoculation, according to the manufacturers instruction (diagnostic hybrids, inc., usa). the isolation of influenza viruses was performed on mdck cell culture by the protocol recommended by cdc, usa. we detected ( ae %) influenza virus-specific nucleic acid fragments from all tested samples by rt-rt-pcr. among the positive samples, there were ae % a(h n ), ae % a(h n ), ae % influenza b, and ae % a(h n )pdm with different distributions by time series in different age-groups. inoculation of the cell lines by rt-rt-pcr positive samples selected randomly has detected influenza virus in ae % ( ⁄ ) on mdck cell culture and % ( ⁄ ) on r-mix hybrid cell culture with varying distribution for different strains. in other words, mdck cell culture technique was better for isolation for pandemic influenza viruses and dfa using r-mix hybrid cell culture technique for detection of seasonal influenza viruses (table ) . average times needed for the final results for different methods were: hours for rt-rt-pcr, hours for dfa on r-mix and days for mdck cell culture with two passages at least. the peak of the seasonal influenza a virus detection occurred in the - th weeks of , however the pandemic influenza detection peak was observed in the - th weeks of ( figure ). the outbreaks by seasonal influenza viruses was observed mostly among the children of - years of age, and pandemic influenza virus outbreak was observed mostly in the adults of - years of age. the results of this study indicate that rt-rt-pcr is the most suitable method for decision makers in epidemiological and clinical settings by sensitivity and timeliness. the final results show that r-mix dfa requires times longer, and by mdck cell culturing, times longer periods, than by rtrt-pcr. mdck cell culture technique has a higher isolation of pandemic influenza viruses, and r-mix dfa has a greater detection rate of seasonal influenza viruses by our results. according to our study, with rtrt-pcr, the isolation of positive samples by tissue culture of influenza a viruses was % and influenza b viruses was ae %, which is lower than in similar spanish study. however our study illustrates similar results with a canadian study where the sensitivity of dfa method and tissue culture technique was shown to be lower than rtrt-pcr sensitivity. as recorded by a study of american researchers, r-mix hybrid and conventional cell culture techniques have had similar sensitivity, which does not match the results of our study. however, the results of our study match with the results of italian and american scientists , where the r-mix hybrid method for seasonal influenza viruses is higher than mdck cell culture technique. background: viral kinetics is increasingly used to study influenza infectiousness. the choice of the study design, i.e. when and how many times nasal samples are to be collected in individuals depending on the sample size, is crucial to efficiently estimate the viral kinetics (vk) parameters. material and methods: we performed a model based optimal design analysis in order to determine the minimal number of nasal samples needed to be collected per subject and when to collect them in order to correctly estimate the vk parameters. the model used was a non linear mixed effect model developed with data collected from patients sampled nine times in days (initial design - samples collected), and we used d-optimization for design identification. we also computed the minimal number of participants necessary. results: considering that % of the influenza-like illness cases are not due to volunteer challenge studies have been used since the 's to provide data on virus shedding from the respiratory tract during influenza infection. recently, vk was studied in naturally acquired influenza infection. , these data are invaluable to describe the natural history of influenza-infection and to compute natural history parameters such as the latent period, generation time, or the duration of infectiousness. [ ] [ ] [ ] [ ] however, among the studies used in a meta-analysis about viral shedding kinetics, the designs varied greatly from one to another. these differences led to variable amount of available information concerning the vk. the lack of adequate sampling leads to imprecise estimates. on the other hand, intensive sampling or over-sampling, while associated with highly informative data, may lead to unnecessary discomfort for the patient and cost to the investigator. optimal design is increasingly used to conceive studies and provides cost-efficient designs. here we propose an optimised design to model vk in the case of influenza infection. we defined the number of participants, the number of samples to collect and their allocations. this design allows, at a minimum cost and discomfort, accurate vk curves and allows the natural history parameters to be well described. model a vk population model was proposed for influenza infection. this model describes with eight parameters the relations between free virus, uninfected target epithelial cells, infected epithelial cells, and early immune response. this model was built on a dataset of volunteers from which nasal samples were collected once a day over days. we call this dataset the ''original dataset''. three parameters, the induction of the early immune response, the virus production rate, and the virus clearance, did not show inter-individual variability and were precisely estimated (relative standard error below %). we considered them as fixed in this research work. five parameters were hence considered here: b the infection rate, d the infected cell mortality rate, w the effect of early immune response on virus production rate and v init the initial value of virus titre. in order to correctly estimate these parameters it is crucial to determine a design to collect informative data. optimal designs maximise the amount of information provided by the study. it involves the determination of the number and allocation of sample times per subject as well as the number of participants. d-optimization is based on the maximization of the determinant of the fisher information matrix and thus minimizes the variance of the parameters. we used the fedorov-wynn algorithm implemented in pfim . to maximize this determinant, which implies to pre-define a set of possible sample times. with the hypothesis that the inoculation occurred at : am, we chose three possible hours ( : , : , and : ) for each day with respect of the sleep-time. to validate the design, we simulated datasets of volunteers with the optimised design obtained. we then estimated the population parameters using monolix . for each of the datasets. we compared the estimated parameters obtained with the simulated datasets to the parameters used to build the optimal design. we computed the relative bias as: with n: number of successful estimations among the simulated datasets. h i : parameter value obtained with the ith dataset. h: parameter value obtained with the original dataset. we also compared the observed rse from these simulations with the rse predicted by pfim and the rse obtained with the original dataset. the rse is proportional to ffiffiffi n p , where n is the population size. we can hence deduce the smallest number of participants necessary to obtain rse below %. where rse predicted is the highest predicted rse (here rse for w) with participants and n predicted = and rse min is equal to ae . considering that % of the influenza-like illness cases are not due to influenza virus, the total number of participants should be multiplied by ae . we found that the best design was when all the participants are sampled five times: three times during the second day post-inoculation at : , : , and : hours and twice on the third day post-inoculation at : and : ( figure ). the comparison of the relative bias and rse predicted by pfim and those obtained after simulation and re-estimation of the parameters are shown in figure . v init and d in a lesser extent present bias. fixed effect parameters are precisely estimated and accordingly to pfim except for v init . we found that participants shedding virus or participants with ili symptoms are necessary if % of them are not infected with influenza virus. we propose an optimised design to accurately study the vk of influenza virus with the minimal number of samples. this design is well balanced between the amount of necessary information and the precision of estimation. we found that samples are necessary to precisely fit the vk curves, which is five times less than the number of samples collected in the original study. ??? the samples should be collected during the second and third days after inoculation. yet we showed in a previous work that the incubation period lasted ae days. ??? hence, the optimised sample times correspond to the two-first days of symptoms and this design could be applied to naturally acquired infections studies in which the inoculation time is unknown. an advantage of this design is its practicality and convenience. all samples are collected during the daytime and after the onset of symptoms. it can thus be used for studies with naturally acquired infections. the design was validated with several criteria concerning the accuracy of the estimation with the optimised design. the parameters estimates were generally satisfactory. the parameter describing the effect of the early immune response on the virus production rate was, however, less precisely estimated (predicted rse = %), and the initial value of the viral titre was very different of the one obtained with the original dataset (bias v init on figure ). this is probably due to the fact that it was measured at day post inoculation, and that the inter-individual variability is much higher than at day . furthermore, d (the infected cell mortality rate) seems also to be biased. this may be due to the fact that three parameters were fixed. the model used was developed from experimentally inoculated healthy volunteers with low serum haemagglutinin antibody titre and with virus inoculation time at : am. the applicability of the design to naturally acquired infection would depend on the pathogenicity of the virus as well as pre-existing immunity and the relevance of challenge method to natural influenza acquisition. our design could be directly used to accurately study vk during influenza infections and would reduce the discomfort of patients and the cost of the experimentation. usefulness of a self-blown nasal discharge specimen for use with immunochromatography based influenza rapid antigen test introduction influenza rapid antigen tests (irat) have become very popular and are widely used for confirming suspected clinical diagnosis of influenza in japan. most of the currently used irat that are based on immunochromatography (ic), nasopharyngeal swab, nasopharyngeal aspiration, and throat swab have been approved as specimens for japanese national health insurance purposes. but the specimen collection by these methods gives patients considerable discomfort, and sometimes appropriate specimens cannot be obtained due to patient resistance, especially by children. in the present studies, self-blown nasal discharge was used as the specimen for an irat, and the results were compared with the results of viral isolation and an identical kit primed with nasopharyngeal swab specimens for seasonal influenza viruses and pandemic (h n ) virus. patients who visited any of the clinics that belong to the influenza study group of the japan physicians association in the - and the - influenza seasons with influenza-like illnesses exhibiting findings were registered after providing informed consent. a square plastic sheet of · cm was handed to the patient. nasal discharge was collected by blowing the nose into the plastic sheet as a specimen for irat, i.e. self-blown specimen. two nasopharyngeal swab specimens were also obtained at the same time for irat and virus isolation. self-blown specimens were obtained successfully by ( ae %) of consecutive outpatients in the - season, as seen in table the sensitivity and specificity of various influenza rapid antigen tests have been reported in various settings. [ ] [ ] [ ] [ ] direct comparison of the results is difficult because of differences in patient or influenza virus, characteristics such as age, study designs, and other features. in this study of the - influenza season, the sensitivity, specificity, and accuracy of the ic kit primed with nasopharyngeal swab specimens were ae %, ae %, and ae %, respectively. these results were quite comparable to our results of the - season, in which the overall results of other ic kits were ae %, ae %, and ae %, respectively, indicating that the ic kit used is quite reliable. the sensitivity, specificity, and accuracy of an ic kit will vary by the method of specimen collection. in general, virus titer is considered to be highest with nasopharyngeal aspiration, lower with nasopharyngeal swabs, and lowest with throat swabs. practically, nasopharyngeal swab is the most popular. the sensitivity, specificity, and accuracy of the ic kit with self-blown discharge specimens compared well with those of an identical ic kit primed with nasopharyngeal swab specimens. for self-blown specimens, sensitivity and specificity were ae % and ae % for influenza a, ae % and ae % for influenza b, % and ae % for pandemic (h n ) . self-blown specimens display sensitivity, specificity, and accuracy comparable to that of conventional nasopharyngeal swab specimens. there was no significant difference in sensitivity, specificity, or accuracy between self-blown specimens and nasopharyngeal swab for influenza a, influenza b, and pandemic (h n ) . these results suggest that selfblown specimens are as useful as nasal cavity swab specimens for the diagnosis of influenza in the clinical settings. nasal discharge, obviously, cannot be collected from infants incapable of blowing their own nose or patients who do not develop a nasal discharge. in this study, self-blown specimens were obtained from ae % of the patients. the rate of successful collection was over % in the age groups of - and - years. these rates would seem to be sufficient for clinical use. the procedure of self-blown specimen collection using a plastic sheet is easy and causes no pain or discomfort. it seems to be more acceptable and safe than the other methods, especially for children. furthermore, this procedure reduces the risk of influenza transmission from patients to the medical staff members involved in sample collection. self-blown sample collection may be superior to other sample collection methods in these respects. we previously reported an inverse correlation between the amount of virus in a specimen and the time to a positive reaction. in this study, there was no significant difference in the mean time to a positive between self-blown self-blown specimens enough to be examined were obtained from consecutive outpatients, and specimens showed a tendency to be obtained large amount from children rather than the aged. there were no statistically significant differences between the ic kit results primed with self-blown discharge and nasopharyngeal swab specimens for influenza a, influenza b and pandemic (h n ) . and nasal swab specimens, suggesting that the self-blown specimens contained sufficient viral antigen for the ic kits. the influence of the presence or absence of nasal congestion on the results of the kit was assessed. the sensitivity of selfblown specimens from patients with nasal congestion was significantly lower than that from patients without nasal congestion. it is possible that insufficient capability to blow the nose due to nasal congestion might tend to lead to false negatives. the observation that the time to positive is longer for patients with nasal congestion than for patients without nasal congestion is concordant. application of self-blown specimen collection only to appropriate patients would increase the sensitivity, which would be important in a clinical setting. we tested only two commercial antigen detection kit, the quick vue rapid sp influ kit and quicknaviÔ-flu (denka-seiken co., ltd). the resulting sensitivity, specificity, and accuracy of the ic kit primed with self-blown specimens were considered adequate for clinical use. to confirm the usefulness of self-blown nasal discharge specimens, further investigation is necessary using other kits and in different settings. the usefulness of a self-blown nasal discharge specimen for an influenza rapid antigen test based on immunochroma-tography was evaluated in the - and - influenza season. results suggest that self-blown nasal discharge specimens are useful as specimens for influenza rapid antigen tests based on immunochromatography for not only seasonal influenza viruses, but also pandemic (h n ) virus. the specimen collection by the patients themselves will reduce the burden of other collection methods and the risk of infection to the medical staff. in april , a mixed-origin h n influenza virus was recognized as a new causative agent of influenza-like illnesses (ili) in humans. since its emergence, the virus has spread rapidly throughout the world and caused a pandemic. most commercial rapid antigen tests (rat) can detect influenza a or b viruses, but cannot specifically distinguish pandemic (h n ) virus with seasonal influenza. recent studies have indicated that the poor performance of the rat approach and nonspecific detec-tion of the pandemic (h n ) virus was the main obstacle to their widespread use in private clinics. , with the need for a new rapid kit with reasonable sensitivity and specificity for pandemic (h n ) virus, we developed a new rat kit in collaboration with company, standard diagnostics, inc., (yongin-si, gyonggi, korea). monoclonal antibody (mab) against haemagglutinin (ha) of the pandemic (h n ) virus was developed using korean isolate and applied to the new kit with the mab to seasonal influenza virus. we examined the detection limit of the kit using the serial dilution of korean pandemic virus isolate (a ⁄ korea ⁄ ⁄ ). during december , clinical specimens from patients with ili were collected at sentinel clinics of six provinces in korea. the specimens were tested by the new rat, and the results were compared with those of real-time reverse transcription polymerase chain reaction (rrt-pcr) by us cdc and virus isolation in mdck cell culture to determine the sensitivity and specificity for the diagnosis of pandemic (h n ) . the detection limit of the new kit against ha of a ⁄ korea ⁄ ⁄ virus was confirmed to be pfu ⁄ ml. by contrast, the detection limit against the np protein was pfu. however, when the kit was applied to clinical specimens, no difference between the two targets was found. using rrt-pcr and viral culture as the references, the performance of the ridt is shown in table . among specimens, were tested positive by rrt-pcr and were tested positive by viral culture. among the rrt-pcr confirmed cases, were positive, and among the viral culture confirmed cases, were positive with the new rat. using rrt-pcr as the reference standard, the overall sensitivity of rat was ae % ( % confidence interval (ci): ae - ae %) and specificity was ae % (ci: ae - ae %). with viral culture as the reference, the rat sensitivity and specificity was ae % (ci: ae - ae %) and ae % (ci: ae - ae %), respectively. when analyzed by the regions tested, the sensitivity ranged between ae % and ae % for rrt-pcr and between ae % and ae % for viral culture as a reference. among patients who had a record of their symptom onset and sample collection date, ( ae %) visited the clinic on the day of symptom onset, and ( ae %) visited day later. when the rat performance was evaluated by day of onset, the sensitivity was lower at three or more days after the onset of symptoms; however, the sensitivity was highest at days after onset and reasonable on the day of onset or at day after ( table ). we found that this new rat had reasonable sensitivity and high specificity compared with rrt-pcr and viral culture for detecting the pandemic (h n ) virus. in one recent study, the sensitivity and specificity of the new rat kit was % and %, respectively, and the ha protein for pandemic (h n ) was detected more sensitively than the np protein for influenza a virus. the sensitivity and specificity of our new rat were lower than those of that study. we found that the test performance varied depending on the clinics in which the tests were performed, and this might be attributable to the persons who collected the specimens. although the clinicians were trained well for *ci, confidence interval. **ppv, positive predictive value. ***npv, negative predictive value. collecting specimens, there might be some differences in performance. the new rat kit could detect pandemic (h n ) virus specifically. although the sensitivity was lower than those of rrt-pcr and virus culture, and negative rat results should be confirmed with more sensitive methods, this kit could be useful in sentinel clinics if used with caution. determination of infectious virus titres is central to many experiments designed to study the biology of influenza virus. assays based on the measurements of viral components, whether viral protein or nucleic acid, does not differentiate infectious virus from non-infectious or defective viral particles, which may have no infectivity or biological *three hundred and forty samples with a known date of onset and sample collection were analyzed. ª blackwell publishing ltd, influenza and other respiratory viruses, (suppl. ), - activity. therefore the ''gold standard'' of virus measurement requires bioassays that examine the ability of viral particles to replicate and further infect other cells. titration on madin-darby canine kidney (mdck) cells in a well plate format is commonly used to measure influenza virus titre. this method is labour intensive, subjective in their read out of cytopathic effect, and takes several days to obtain a result. microneutralization tests that quantitate neutralizing antibody titres and assays of drugs for antiviral activity also require well based assays of residual virus infectivity. therefore, technologies that improve on the titration of infectious virus will be of great benefit. this study utilized the xcelligence system (roche applied science), which adopts microelectronic biosensor technology to monitor dynamic, real-time label free and non-invasive analysis of cellular events. the system measures electronic impedance using an array of microelectrodes located at the bottom of each culture well (e-plate ). adherent cells are attached to the sensor surface of electrode arrays, and changes in impedance can be detected and recorded. the xcelligence system can monitor cell events induced by viral infection, such as changes in cell number, adhesion, viability, morphology, and motility. measured electrode impedance is expressed as dimensionless cell index and is graphically represented using software to show the phenotypic changes of a cell population over time. the aim of this study is to demonstrate that using this platform to measure real-time cell index has potential to circumvent many of the limitations of the currently established procedures of end point titration of virus infectivity and for microneutralization assays. madin-darby canine kidney cells were propagated in growth medium consisting of minimum eagle's medium (invitrogen) supplemented with % fetal bovine serum (invitrogen), ae mg ⁄ l penicillin (invitrogen), and mg ⁄ l streptomycin (invitrogen), with incubation at °c in a % co humidified atmosphere. influenza a ⁄ hong kong ⁄ ⁄ (h n ), a seasonal influenza virus from a patient who suffered from a mild febrile illness, was propagated in mdck cells maintained in virus medium consisting of minimum eagle's medium (invitrogen) supplemented with ae mg ⁄ l penicillin (invitrogen), mg ⁄ l streptomycin (invitrogen), and mg ⁄ l np-tosyl-l-phenylalaninechloromethyl ketone-treated trypsin (sigma, st louis, mo, usa), with incubation at °c in a % co humidified atmosphere. virus stocks were aliquoted and stored at °c until use, and the % tissue culture infectious dose (tcid ) of the virus stock was determined by titration in mdck cells according to standard procedures, and the tcid of the stock virus was calculated by the method of reed and muench. to perform a microneutralization assay, mdck cells seeded at a density of cells ⁄ well in an e-plate was removed from the xcelligence system after approximately hour; growth medium was then removed, cells washed, and replaced with ll virus-medium. a human serum, which is known to contain high titre antibody against the h n virus was heat inactivated for min at °c, and twofold serial dilutions were performed in virus medium. the diluted serum was mixed with an equal volume of virus medium containing influenza virus at tcid ⁄ ll. after incubation for h at °c in a % co humidified atmosphere, ll of virus-antibody mixture was added to the mdck cells to give each well an equivalent virus dose of tcid . a back titration of the virus challenge dose was performed, and a cell control (free of virus) was performed in quadruplicates. after incubation at room temperature for minutes, the e-plate was then placed back onto the xcelligence system in the incubator and maintain at °c with % co , and the cell index values were measured every minutes for at least a further hour. the same procedures were performed with cells seeded in conventional well cell culture plates for parallel comparison with the currently used standard method. in this case, cells were examined for cytopathic effect under an inverted microscope after days of infection and the lowest virus dilution, which protected the cells from viral induced cytopathic effect taken as the neutralizing end point. after hour of seeding mdck cells at cells ⁄ well, standard microneutralization assay for influenza virus was performed. integral to this assay, a serial titration of the input virus at ae log increments was carried out. wells infected with the undiluted virus ( tcid ⁄ well), the cell index commenced dropping at a steeper gradient than the no-virus cell control after approximately hour of infection ( figure ). this drop in cell index continues at a consistent slope until it flattened out when approaching zero cell index. this steep decrease in cell index with constant gradient was also observed for virus dilutions up to and including log ( -folds), and the profile shifted with increased time in proportion to the dilution made to the virus. virus dilutions beyond log have cell index profiles similar to the no virus input control, and this corresponds to the absence of cytopathic effect as determined by microscopic observation at hour after infection. hence, there was a correlation between the amount of virus used for infection, the onset of the influenza virus-mediated cytopathic effect, and the steep decline in cell index. a human serum with known microneutralization antibody titre to h n virus was used in this study to investigate the real time cell index changes that occur during the assay ( figure ). using influenza virus treated with serum dilutions up to and including a dilution of : , the cell index profile remained essentially the same as the no virus cell control, which correlates with the lack of cytopathic effects under microscopic observation at hour of infection. at a serum dilution of : , the steep decrease in cell index, which is characteristic of cellular cytopathic effect induced by the virus, became evident at around hour post infection, and this was reduced to hour when serum dilution of : was used. in contrast, for the virus -no antibody control, the onset time for this steep decrease in cell index occurs at approximately hour. for both serum dilutions of : and : , full cytopathic effect was observed microscopically at hour of infection. from microscopic observation of cytopathic effect, according to the current standard procedures, the neutralizing titre of the human serum used in this study is at : as it is the last dilution of the serum that prevented cytopathic effect from being detected. an essential part of the microneutralization assay is to confirm the titre of the input virus (normally tcid ⁄well) by performing a titration assay with decreasing serial dilutions of the virus. under normal procedures, cells are examined microscopically after hour of infection for sign of cytopathic effects. in the case of mdck cells, the cytopathic effect is cell death, which is indicative of the presence of live influenza virus infecting and replicating in the cells. therefore, the titre of the virus is taken as the last dilution in which cytopathic effect is present. parallel realtime cell index measurements demonstrated that for wells with cytopathic effects, the profile exhibits a steep gradient linear decrease in cell index after infection with the virus, which can be termed the ''cpe plunge.'' the time in which the cpe plunge became evident appears to be inversely proportional to the amount of virus, therefore the opportunity exists to utilize this aspect to calculate or compare quantitatively different virus concentrations. for unequivocal assignment of cytopathic effect, it normally requires - days after infecting the cells, with days after infection being the standard time to read virus titration and microneutralization assays. using the real-time cell index monitoring, it is found that apparent cytopathic effect can only be observed microscopically when the cell index has dropped to near zero. as the time of onset of the ''cpe plunge'' becomes evident many hours prior to observable cytopathic effect, it is possible that the time to results can be drastically reduced after some formulation of the method. we compared the current standard method in perfoming a microneutralization assay with one utilizing the real-time cell index measurement to investigate whether this approach is able to offer better performance over the existing one. the current standard neutralization assay is the microscopic observation of antibody mediated protection from virus cytopathic effect in mdck cells. this study showed that this may also be achieved by examining the profile generated from the real-time measurements of the cell index. using real-time cell index monitoring, it is possible to detect inhibitory activity at higher dilutions of the anti-serum than can be detected by the standard microscopic observation of cytopathic effect. therefore, the realtime cell index monitoring could potentially be developed to be a more sensitive method for measuring anti-viral activity. as drug resistant strains of influenza a viruses including the pandemic h n are being reported, the real-time cell based monitoring system may also have the potential to be developed for use as a diagnostic platform for drug resistance assays. this study suggests that real-time cell index monitoring has the potential to substantially reduce human resources in reading results, as well as reducing time-to-result of these assays from days to two. the saving could be substantial for work involving bio-hazard level ⁄ pathogens such as h n viruses as personnel working with these organisms are require to be highly trained and experienced. in addition, the reduction in transferring plates to and from the microscope in reading cytopathic effect will substantially reduce the possibility of accidents from occurring. furthermore, the system provides objective digital data to an otherwise subjective assay method, which can improve standardization, data exchange, and hence collaboration between different laboratories. with more detailed validation and development, real-time cell index monitoring could transform the way we study and diagnose infection with pathogens such as influenza viruses. the emergence of a novel h n influenza a virus of swine origin, the pandemic a(h n ) , with transmissibility from human to human in april posed pandemic con-cern and required modifications to laboratory testing protocols. a new protocol for universal detection of influenza a and b viruses and simultaneous subtyping of influenza a (h n ) virus, composed of two-one-step rt-pcrs, fast set infa ⁄ infb and fast set h n v (relab, italy), was evaluated and compared to the reference protocol recommended by who. fast set infa ⁄ infb was able to detect influenza a and b viruses circulating between and belonging to different subtypes and lineages, and no cross reactions were observed by either fast set infa ⁄ infb or fast set h n v. the who assay was found to have a slightly lower end-point detection limit ( ) dilution) in comparison to the new protocol ( ) ). specificity of the assays was % as assessed on a panel of stored clinical samples including adenovirus, respiratory syncytial virus, metapneumovirus, parainfluenza virus, s. pneumoniae, n. meningitidis, h. influenza, and human influenza viruses. the new assay panel allows the detection, typing, and subtyping of influenza viruses as requested for diagnostic and surveillance purposes. the high sensitivity of the protocol is coupled with capacity to detect viruses presenting significant heterogeneity by fast set infa ⁄ infb and with high discriminatory ability by fast set h n v. a rapid and sensitive assay for the detection of influenza virus in clinical samples from subjects with ili or low respiratory tract infections is a fundamental tool for epidemiological and virological surveillance, management of hospitalized patients, and control of virus nosocomial transmission. the emergence, in april , of a novel h n influenza a virus of swine origin, the pandemic (a(h n ) ), with transmissibility from human to human poses pandemic concern and required modifications to the laboratory testing protocols. molecular diagnosis of influenza is generally achieved through a twophase process: a screening phase for the detection of virus, and the subsequent strain characterization performed by either sub-type-specific rt-pcr or entire ⁄ partial genome sequencing. during a pandemic, simultaneous implementation of both the detection of influenza a and b influenza viruses and identification of the new subtype is useful for clinical and epidemiological reasons. here, we describe a new protocol including two-one-step rt-pcrs, fast set infa ⁄ infb and fast set h n v (relab, italy) that allows universal detection of all influenza a viruses and, simultaneously, all subtypes that are influenza a(h n ) . specificity and clinical sensitivity of the two-one-step rt-pcrs (fast set infa ⁄ infb and fast set h n v; relab, italy) were evaluated by testing selected specimens, including: • fifty samples collected from nasopharyngeal swabs representative of influenza viruses, belonging to differ-ent subtypes and lineages, and other respiratory viruses and bacteria circulating in italy between and . • six purified a(h n ), a(h n ), and a(h n ) strains, kindly supplied by alan hay, who influenza centre, london, uk. • two hundred-fifty influenza positive samples selected according to type, subtype, clade and viral concentration from > specimens received by the liguria influenza reference laboratory between january st and december st, . since , nasopharyngeal swabs sampled from patients suspected of having contracted the influenza virus have been collected in viral transport medium, and upon arrival into the laboratory, the samples were divided in ‡ aliquots. those not immediately processed were stored frozen at ) °c. stored samples were used for this evaluation, and all specimens were re-extracted for the study. samples collected between and included specimens positive for: no seasonal a(h n ) have been detected since january st, . furthermore, weak positive sample using fast set infa ⁄ infb, but negative at block pcr and typing ⁄ subtyping assays was tested. the analytical sensitivity of the test under investigation was determined testing ten-fold serial dilutions of seasonal influenza a(h n ), seasonal influenza a(h n ), new pandemic influenza a(h n ) , and b cell culture-grown viruses. the intra-assay reproducibility was measured by testing the same a(h n ) positive sample times in the same experiment, while the inter-assay reproducibility was confirmed by testing the same samples in independent experiments. to evaluate the performance of the protocol, all samples were tested using a block pcr confirmation test (seeplex Ò rv ace detection), and all specimens collected between january st and december st, and dilutions were also assayed using the recommended who ⁄ cdc protocol of real-time rtpcr for influenza a(h n ). typing and sub typing were performed using the who protocol and ⁄ or sequencing. viral rna was extracted from swabs using the qiaamp viral rna mini kit (qiagen) according to the manufacturer's protocol. fast set infa ⁄ infb and fast set h n v are two multiplex one-step real time pcr assays developed and evaluated by the liguria regional reference centre for diagnosis and surveillance of influenza in collaboration with relab diagnostics. both assays contain primers and a dual-labelled hydrolysis probe that targets two regions of the matrix gene (table ) . amplification conditions were as follows: reverse-transcription °c for minutes, denaturation °c for minutes, then cycles of °c for seconds, °c for seconds. the entire amplification process extended for minutes. an internal control real-time assay was also incorporated in order to detect pcr inhibition, failed extraction ⁄ pcr and technical error. the cdc realtime rtpcr (rrtpcr) protocol for detection and characterization of swine influenza includes a panel of oligonucleotide primers and dual-labelled hydrolysis (taqman Ò ) probes to be used in real-time rtpcr assays for the in vitro qualitative detection and characterization of swine influenza viruses in respiratory specimens and viral cultures. this protocol recommends three primer-and-probe sets: infa, amplifying a conserved region of the matrix gene from all influenza a viruses; sw infa, designed to specifically detect the nucleoprotein (np) gene segment from all swine influenza viruses and sw h , designed to specifically detect the hemagglutinin gene segment from a(h n ) . the seeplex Ò rv ace detection for auto-capil-lary electrophoresis is a multiplex block rt-pcr that applies dpoÔ (dual priming oligonucleotide) technology and is designed to detect major respiratory viruses, respiratory rna (influenza a and b virus, parainfluenza virus type , and , respiratory syncytial virus a and b, rhinovirus a ⁄ b, coronavirus oc and e ⁄ nl ) viruses and dna (adenovirus) virus, from patients' samples including nasopharyngeal aspirates, nasopharyngeal swabs and bronchoalveolar lavage. conventional viral culture was performed inoculating ae ml of each specimen into mdck-siat seeded into -well plates for influenza isolation. virus detection was performed by the hemagglutination test using ae % guinea pig red blood cells (rbc). specificity and clinical sensitivity results of the new protocol are reported in table . fast set infa ⁄ infb was able to detect influenza a and b virus circulating between and belonging to different subtypes and lineages, and no cross-reactions were observed by either fast set infa ⁄ infb or fast set h n v. among specimens collected between january st and december st, , all fast set infa ⁄ infb and fast set h n v high titre positive samples resulted positive using the who ⁄ cdc assay and showing reactivity using infa and sw infa primer-andprobe sets. among low titre a(h n ) positive samples at fast set infa ⁄ infb, ( ae %) were not detected by the who ⁄ cdc assay, but were positive using seeplex Ò rv . the who ⁄ cdc sw h primer-and-probe set works in ae % ( ⁄ ) and ae % ( ⁄ ) of high and low titre a(h n ) positive samples, respectively. all a(h n ) strains collected during and initially detected by fast set infa ⁄ infb were confirmed after rna re-extraction by seeplex Ò rv and who ⁄ cdc assay showing reactivity using the infa primer-and-probe set. all infa ⁄ infb were confirmed after rna re-extraction by seeplex Ò rv . one influenza a case identified by the who ⁄ cdc kit (infa primer-and-probe set, ct values: ae , sw infa primerand-probe set: negative) and new protocol (a primer-andprobe set, ct values: ae , a(h n ) primer-and-probe set, ct values: ae ) was not detected by either seeplex Ò rv or by who subtyping protocol and ⁄ or sequencing, suggesting a very low viral load or unspecific results by real time assays. the analysis of serial dilutions of cell culturegrown a(h n ) showed that the detection limit of fast set infa ⁄ infb, fast set h n v, and seeplex Ò rv was identical ( ) ) and log lower than that using the who ⁄ cdc protocol ( ) ). a similar analysis with respect to a(h n ) and a(h n ) strains indicated that fast set infa ⁄ infb sensitivity ( ) and ) , respectively) was log lower than that showed by seeplex Ò rv ( ) and ) , respectively). in comparison with the new protocol, the who ⁄ cdc assays, considering infa primer-and-probe set, was found to have a slightly lower end-point detection, detecting the ) a(h n ) and a(h n ) dilution. also in detecting influenza b virus, fast set infa ⁄ infb sensitivity ( ) and ) , respectively) was log lower than that showed by seeplex Ò rv and the who ⁄ cdc protocol. data on intra-assay and inter-assay precision, measured as cv% of ct showed that the dispersion indices observed had values of less than %. since samples were detected using the new protocol that resulted negative using the who ⁄ cdc assays. the unfortunately low quantity of low titre a(h n ) samples collected during did not allow us to highlight differences between assays fast set infa ⁄ infb, and fast set h n v positivity was always confirmed by seeplex Ò rv , which demonstrated high sensitivity, showing a detection limit comparable or lower when compared with those observed using the who ⁄ cdc assays. the high analytical sensitivity of seeplex Ò rv is reported by kim who observed a detection limit of copies per reaction for each type ⁄ subtype of influenza viruses. the high sensitivity of the new protocol is coupled with its capacity to detect viruses presenting a significant heterogeneity by fast set infa ⁄ infb and high discriminatory ability by fast set h n v. fast set infa ⁄ infb was able to identify representative influenza viruses of circulating strains during the last decade belonging to different subtypes, lineages, and clusters, and fast set h n v primerand-probe set reacted selectively with a(h n ) target. a recent report demonstrated that the sw infa assay is not specific to a(h n ) and is able to detect both human and avian (h n ) influenza a viruses and so there is the potential for misidentification. high titre (ct ae and ae at fast set infa ⁄ infb) a(h n ) viruses did not react with fast set h n v primer-and-probe set (data not shown). available human a(h n ) sequences are similar within the h n v primer-and-probe regions, but having - mismatches in the forward primer and, more notably, two of the mismatches occurred within nucleotides of the end, an important determinant for primer specificity. in conclusion, this protocol can be a powerful tool in the diagnostic laboratory setting for specific simultaneous analysis of several samples in minimal time, showing enhanced sensitivity in detecting influenza viruses, and high discriminatory ability in identifying the new pandemic a(h n ) . a university-corporate partnership to enhance vaccination rates among the elderly: an example of a corporate public health care delivery public health campaigns usually rely on governmental infrastructure and finance for vaccine implementation programs. however, there are many financial and physical barriers which preclude widespread and effective vaccine administration, especially among the elderly. on an international scale, both government agencies and citizen groups have a vested interest in searching for more resourceful methods of attaining significant immunization levels (> % of the population). in fact, it seems to have become both a grassroots civic and governmental goal, especially among developing countries. we implemented the unique strategy of enlisting the assistance of a privately-owned food market chain to address the public health issue of mass vaccination for the elderly. in this context, publix pharmacy and the university of south florida (usf) recently developed both a handbook and a training program to facilitate the administration of vaccinations. between and , the publix-usf partnership resulted in administration of over thirty thousand influenza a (h n ) vaccinations, % of which were given to adults over years of age. consequently, vaccine administration costs were decreased by using corporate resources and bypassing overly strained municipal resources. this unique university-corporate partnership successfully delivered h n vaccine to a vulnerable cross-section of society at a lower cost and with minimal side effects and morbidity. it may be safely projected that university-corporate partnerships could result in an effective method for rendering a vital service to an aging and especially vulnerable segment of the population. government policy and funding are the foundation of immunization programs on an international scale. for example, in the united states, governmental programs account for over % of the monetary outlay used for immunization. until , the global alliance for vaccines and immunizations (gavi) acted as a catalyst for implementing vaccine and immunization programs in each targeted country. under the auspices of gavi-collaborations between governments, charitable organizations, and multinational health agencies (such as uncief and the who)-many countries have increased their spending for vaccination programs. however, development of financially sustainable immunization programs geared toward reaching the majority of the population are still at a nascent level of evolution. the development of more innovative and costeffective approaches has become imperative in order to reach a greater number of vaccination candidates. administering the influenza vaccine only to the subpopulation of over year olds would save an estimated quality-adjusted life years in a cohort of approximately half the world's population. widespread public vaccination programs are made more complex by the continuing development of newer vaccines, concomitant specialized administration costs, and the logistical challenge of conveying recipients to vaccination points of service. , in spite of the increasing complexity of mass vaccination, cost-benefit analyses clearly favor annual influenza vaccination in the elderly population on an international scale. , recently, in , influenza vaccine administration was reported to reach between % and % of the elderly population, which denotes varying degrees of success within each particular country. , however, there was also a report of a uniform plateau effect at around % of the population, beyond which additional vaccination coverage was difficult to achieve. physical limitations to vaccination seem to be more insurmountable for the elderly. unfortunately, this is the population segment which could experience the most significant vaccination-associated mortality reduction. we employed the unique strategy of involving the resources of publix supermarkets, a corporate food market chain, to address the public health issue of widespread vaccination for the elderly. we took advantage of recent changes in the florida statutes, which expanded the scope of pharmacists' practice to include administration of vaccines. subsequently, publix pharmacy and the university of south florida (usf) developed a handbook and training program to facilitate and enhance vaccine administration by publix pharmacists. by using proprietary pharmacists and more practical supply storage, we were able to decrease the costs of vaccine administration. the consumer was charged $ for administration costs plus the cost of the injection itself, regardless of insurance or eligibility for governmental subsidy. although patients were initially self-selected, they were ultimately excluded if they had demonstrated prior adverse effects to influenza vaccinations or to any of the components of such vaccinations. between and , the publix-usf partnership vaccinated people against influenza a (h n ), of which were florida residents. the age range was - years old with a median age of years old. seventysix percent of the participants were over years old (see figure ). within the population surveyed, the reported side effects of the vaccine in this study were not serious, but included: vertigo, cold sweats, chills, vomiting, syncope, rash, nausea, stomach pain, elevated blood pressure, injection site reaction, inflamed bursa, and bilateral thigh discomfort. participants from all socioeconomic classes were vaccinated. an income-by-zip code analysis revealed % of those vaccinated resided in zip code areas where the average household income was <$ per year. of those remaining, % had an average income of $ -$ per year, and % had an income of >$ per year. each person vaccinated was charged ten dollars for administration costs. this represents a decrease in the administration costs ranging from one dollar to ten dollars saved per vaccine. , conclusion this unique university-corporate partnership successfully delivered h n vaccine to a high-risk population with decreased vaccine administration costs. the influenza vaccine is well-tolerated, with minimal side effects when patients who have a history of adverse reactions are excluded. we can postulate that university-corporate partnerships may indeed be effective at reaching the aging population which is a challenge in most communities. this delivery model may prove to be another tool for improving the efficiency of mass immunization by facilitating accessibility, which results in wider coverage. this model also enhances delivery of healthcare by decreasing costs of immunization regardless of whether the payer is a government, insurance company, or self-pay consumer. the gavi initiative stressed three goals for accomplishing sustainability and independence in immunization programs. the goals were to: (i) mobilize additional resources from governmental and non-governmental sources; (ii) improve program efficiency to minimize additional administration resources needed; and (iii) increase the reliability of funding. empowering privately owned corporations within the community, such as food markets or pharmacies, to administer vaccines mobilizes additional resources to readily achieve the first goal of gavi. mobilizing resources of non-healthcare, corporate vaccination locations enhances accessibility due to travel convenience. in our study, participants came from all socioeconomic classes, suggesting that ease of access is independently hindering mass vaccination, and that people of all incomes are more likely engaged when access issues are eliminated. the second and third goals were also accomplished by recruiting a corporation's resources for vaccine administration (refrigeration, storage, and employees). this minimizes the money spent from vaccine program funds to support the infrastructure of immunizations, thus improving financial efficiency and sustainability. financial efficiency implies that money is spent to safely reach as large a portion of the population as possible. by using corporate storage facilities instead of paying for independent facilities, money can be spent elsewhere. more vaccines can be purchased and more money can be spent on media communications to encourage vaccination. sustainability requires the ability to fund annual vaccination programs which reach % of the population or greater. key to the control of pandemic influenza are surveillance systems that raise alarms rapidly and sensitively. in addition, they must minimise false alarms during a normal influenza season. we develop a method that uses historical syndromic influenza data from the existing surveillance system 'servis' monitoring seasonal ili activities in scotland. we develop an algorithm based on wcr of reported ili cases to generate an alarm for pandemic influenza. wcr is defined as the ratio of the number of reported cases in a week to the number of cases reported in the previous week. from the seasonal influenza data from scottish health boards, we estimate the joint probability distribution ( figure ) we compare our method, based on our simulation study, to the mov-avg cusum and ili rate threshold methods and find it to be more sensitive and rapid. the wcr method detects pandemics in larger fraction of total runs within the same early weeks of pandemic starting than does any of the other two methods ( figure ). as shown in the table, for % pandemic case reporting rate and detection specificity of %, our method is % sensitive and has mdt of weeks, while the mov-avg cusum and ili rate threshold methods are, respectively, % and % sensitive with mdt of weeks. at % specificity, our method remains % sensitive with mdt of weeks. although the threshold method maintains its sensitivity of % with mdt of weeks, sensitivity of mov-avg cusum declines to % with increased mdt of weeks. for a two-fold decrease in the case reporting rate ( ae %) and % specificity, the wcr and threshold methods, respectively, have mdt of and weeks with both having sensitivity close to %, while the mov-avg cusum method can only manage sensitivity of % with mdt of weeks. the first cases of the pandemic were reported in scotland in the th week of the season. the wcr algorithm as well as the mov-avg cusum method detects the pandemic weeks later in week . the ili threshold method detects it week later in week . both the wcr and mov-avg cusum methods therefore outperform the ili threshold method by week in the retrospective detection of the pandemic in scotland. while computationally and statistically very simple to implement, the wcr method is capable of raising alarms rapidly and sensitively for influenza pandemics against a background of seasonal influenza. although the algorithm has been developed using the servis data, it has the capacity to be used at large scale and for different disease systems where buying some early extra time is critical. more generally, we suggest that a combination of different statistical methods should be employed in generating alarms for infectious disease outbreaks. different detection methods would provide cross-checks on one another, boosting confidence in the outputs of the surveillance system as a whole. real-time evidence being created worldwide will greatly contribute to the full understanding of influenza pandemics. here we report the real-time epidemiology and virology findings of the influenza a(h n ) pandemics in mongolia. the epidemiological and virological data collected through isss of nic, nccd, mongolia (real-time information on registered ili cases and virological laboratory results are available from the weekly updates in the nic, mongolia website: http://www.flu.mn/eng/index.php?option=com_ content&task=category&sectionid= &id= &itemid= ) were used for analysis in relation to the previous seasonal influenza activities in the country. influenza viruses were detected in naso-pharyngeal samples from ili patients by rt-rt-pcr with applied biosystems fast real time pcr system , using primers and instructions supplied by cdc, usa. influenza viruses were isolated by inoculation of rt-rt-pcr-positive samples of mdck cell culture according to the standard protocol. ten representative strains of a(h n )pdm viruses were selected for sequencing of different gene segments, namely: a ⁄ ula- , and a ⁄ dundgovi ⁄ ⁄ . sequencing of influenza virus gene segments was performed in applied biosystems xl genetic analyzer using primers and instructions supplied by cdc, usa, and bioinformatic analysis was performed with abi ⁄ seqscape v. . and mega programs. the pandemic alert in mongolia was announced by the government on april , , just after the who announcement of the pandemic alert phase, and planned containment measures were intensified. despite intensive surveillance, no a(h n )pdm virus was detected in mongolia until the beginning of october . around suspected cases, mostly arriving from the a(h n )pdm epidemic countries, tested zero by rt-rt-pcr for a(h n )pdm virus. the first a(h n )pdm case detected by the routine surveillance system in ulaanbaatar city, the capital of mongolia, was confirmed by rt-rt-pcr on october , ( st week of ). the reported ili cases escalated rapidly, reached the peak in the - th week of , and gradually decreased thereafter ( figure ). week of . however, the registered ili cases increased again from the th week of , and peaked at the - th weeks of . the viruses isolated during this nd peak were influenza b strains ( figure and table ). for the genetic characterization of the mongolian pandemic isolates, gene segments i (pb ), gene segments ii (pb ), gene segments iii (pa), gene segments iv (ha), gene segments v (np), gene segments vi (na), gene segments vii (m), and gene segments viii (ns) of the representative a(h n )pdm mongolian strains were sequenced, and all sequences have been deposited in the genbank (accession numbers: cy , cy , cy , cy , cy , cy , cy , cy , cy , cy , cy , cy , cy , cy , cy , cy , cy , cy , cy , cy , cy , cy , cy , cy , cy , cy , cy , cy , cy , cy , cy , cy , cy , cy ). all genes of mongolian strains were possessing ae - ae % similarity with the genbank deposited gene sequences of the original pandemic strain a ⁄ california ⁄ (h n ). the who declared the pandemic alert phase (phase iv) on april , , and was prompted to announce the pandemic phase (phase v) two days later. after days, the who declared the beginning of the pandemic peak period (phase vi) on june , . however, in mongolia, the pandemic alert period continued for days. mongolia was free of the pandemic virus during the whole first wave of the pandemics in the northern hemisphere. with the confirmation of the st influenza a(h n )pdm case on october , in ulaanbaatar, mongolia entered into the pandemic phase (phase v), and after just weeks, the registered ili cases peaked, confirming mongolia shifted into the pandemic peak period (phase vi), which i i i v i i v i v v v i i i i iii iv v vi vii viii worldwide by who in mongolia coincided with the nd wave of pandemics in many countries of the northern hemisphere (see, picture and table ). despite the relatively milder clinical manifestations, the disease burden for the health service was enormous, while the morbidity per population at the peak period was - times higher above the upper tolerant limit, and - times higher above the seasonal influenza outbreaks. in contrast to the seasonal influenza outbreaks where over % of the registered ili cases have been in the age group under , it has been observed that over % of the registered cases in this pandemic peak period were in the age group of - . on january , , we regarded the pandemic had entered into the post-peak period (phase vii) when the registered ili cases became lower than the upper tolerant limit, during which time mongolia experienced an influenza b outbreak. on may , we determined that mongolia entered the post-pandemic period (phase viii) as the influenza virus isolations were almost stopped, and after no pandemic virus detected for months. who announced pandemic vii and viii phases much later. , this first ever real-time laboratory confirmed influenza pandemics in mongolia and confirmed some variations of pandemic spread in different parts of the world. the comparison of deduced amino-acid sequence changes have shown that the mongolian strains belong to the clade , according to the classification of a(h n )pdm influenza strains suggested by m. nelson, which has circulated worldwide since july . this is also evidence that the st wave of the pandemics did not hit mongolia. the who public health research agenda for influenza is aimed to support the development of evidence needed to strengthen public health guidance and actions essential for limiting the impact of influenza on individuals and populations. each stream-specific group reviewed and discussed the proposed organization, content, rationale, and global health importance of their designated research stream. specific research recommendations were made for topics within each stream: background: a syndromic surveillance system using nonclassical data sources for detection and monitoring evolution of flu and flu-like illness (ili) in djibouti is reported here as part of the preliminary report of djibouti who-copanflu international study (wcis)**. methodology: clinical reports, over-the-counter drug sales, lab diagnosis report, and health communication trends were obtained for an integrated statistical analysis. results: transition to winter is concomitant with upsurge of ili cases and ili drug sales. in addition, more rural folks manage ili infections on self medicament than through clinical consultancy. inefficient and vague data collections were observed. a successful implementation of wcis will create a platform upon which challenges faced in djibouti health department in routine surveillance will be addressed to achieve a near-real time surveillance of flu pandemic. conclusion: innovations, prompt reporting, and instituting open source syndromic surveillance system software's in resource limited environment like djibouti will enhance early detection and evolution monitoring of pandemic flu. the spanish flu in ⁄ infected and killed millions of people, and threatened to wipe humanity off the face of planet. however, the recent scenarios of influenza h n ( ) pandemics' worldwide occurrence fell short of most scientific prediction on its magnitude and intensity. this dampened their confidence; they cannot state precisely as to when, how, where, and which of the spanish flu-like pandemic will occur in the future. in support of scientific community and governments, the who hasn't gone to slumber, but is reminding its member states to up their post pandemic surveillance and monitoring of influenza virus in circulation for advance preparedness in case of an outbreak. despite all uncertainty around the pandemic flu h n , there remains a common knowledge and understanding that this flu has shown a great potential to evolve and cause huge morbidity and mortality. although its future magnitude may be unpredictable, its recurring events have severe consequences on human health and the economic well being of everyone. and therefore, advance planning and preparedness is critical in protecting any population in the future, especially those located in resource limited environment without universal health cover and generous disaster emergency funds. . two collapsed sets of a weekly and monthly mean data (of four years period) were clustered in five categories of ili cases, drug sales, lab results, vaccine consumption, and health promotion. this was followed by a descriptive statistics analysis of cumulative weekly and monthly data to establish presence or absence of trend. time series analysis was not done due to data limitation. copanflu program: as at the time of going to press, the cohort study is at the household recruitment and inclusion phase and the study covers the djibouti city. it is in our intention to use the cohort study findings to validate or improve the niph ministry of health djibouti ili surveillance effort for better preparedness. clinical service: % of all health facilities are in djibouti city. of the ae % ( ) of the population that seeks medical care on influenza and influenza like illness each year, ae % ( ) and ae % ( ) of them are attended to at the city's public and private clinics, respectively ( figure ). the rest are attended from the regional health centers. the majority of ili incidence sharply rise with the onset of the winter season (october to april), affecting mostly the middle age group ( - years). pharmaco-surveillance: % ( ) of total prescriptions were antipyretic and antiflu drugs, ae % ( ) of which were consumed by peripheral regions, the non dji- lab diagnostics: the annual ili lab diagnosis was negligible ae % ( ), which can be attributed to less equipped virology laboratories to warrant routine service utility. documented cases were from previous bouts of avian influenza that had a human incidence from and . with support of egypt-based naval army medical research unit three (namru ), clinicians were motivated to sample all ili patients and submit to collaborating international reference influenza lab in cairo, egypt. vaccination: influenza vaccinations were undocumented, but at least ae % ( ) of population sought the service (for yellow fever and meningitis) as mandatory travel advisory or as childhood immunization need. at the time of going to the press, there were at least vaccine doses of h n ( ) virus donations yet to be administered. health promotion and hygiene: print and audiovisual risk communication remained favorite means of reaching out to urban dwellers ( ae %). while to the rural and nomadic population, person to person communications was the preferable means. to increasing public awareness that will encourage reporting of ili cases and entrench risk aversion health behavior that limits flu spread, who-copanflu international study djibouti has incorporated basic training on ili infection and personal hygiene by interviewers during household inclusion. improving national epidemic surveillance capacity and response under new international health regulation is important for any nation, including djibouti. our finding indicates the winter season predisposes one to ili infections; they therefore opt for medical services or self medication depending on their capability and ⁄ or understanding. in djibouti, almost no city dwellers favors self medication over clinical consultation, suggesting the presence of inhibitory factors like distance from the health centers and the cost of accessing consultancy. common in the absence of universal primary health care setting, it therefore calls for active innovativeness in outbreak detection, disease reporting, and preventive medicine on the part of health authority so as to achieve good population health. in respond to these, niph has turned resource limitation to a motivation instead and is working towards institutionalizing a near-real-time syndromic surveillance system as a core functional unit. it capitalizes on three major aspects within its reach: prompt accurate data generation for analysis, ehesp wcic-study input, and information technology use. prompt accurate data generation for analysis: data used in our analysis suffered from un-timeliness (weekly instead of daily basis), incompleteness (vague over-counter drug sales records), entry errors (incidence case reports), and poor collection format (most of data collection forms). use of satellite handset phones for regional health centers and mobile phones for city sentinel clinics will reduce unnecessary data delivery delays. in addition, creating awareness to data entry personnel on the importance of careful and completeness of entries is important, as is the need to reformat data collection forms to capture exact aspects of surveillance needs for relevant executable analysis. besides alerting for immediate impending epidemics, these data can also be adopted for projective predictive modeling of annual epidemics, including that for influenza. ehesp wcic-study input: djibouti wcic-study is complementary to the existing syndromic surveillance system, but with emphasis on flu and flu-like illness. various innovations as suggested above are used in seeking to overcome the prevailing challenges. while every attempt is made to realize its (wcic-study) objective and for global comparison, lessons learned from successful implementation will form a platform for future refined syndromic surveillance protocol as equally reported elsewhere in asian countries. , information technology: national institute of public health djibouti has an informatics department with sufficient working pcs and personnel to execute efficient data collection and management for epidemiological analysis. however, licensing cost of near-real time syndromic surveillance software is prohibitive, but the open access software with capacity to generate custom graphs, maps, plots, and temporal-spatial analysis output for specific syndromes should make implementation a lot easier. such output for conditions like flu (or gastroenteritis) will be essential to cause prompt response of the local public health office and international partners in saving lives and suffering of djibouti people. pandemic flu surveillance and preparedness requires multifaceted, interdisciplinary, and international approach whose efficiency and efficacy can only be refined over time. building on the health care system's swot for preparedness, the ehesp wcic-study promises to refine surveillance system operation and knowledge on individual's risk determinants to swine flu (h n ) virus infection at the household level in djibouti. these efforts are ultimately creating available control options at the time of need (pandemic occurrence), and at the same time exploring investment in quality data profiling and information technology, which will include syndrome surveillance software systems like essence, ewors, or other open sourced ones. the antibody efficacy -which compares the illness frequency between those with and those without a protective level of pre-epidemic hi antibodies ( ‡ : ) -has been proposed ; however, this index has rarely been used due to practical difficulties in confirming the strain-spe-cific disease corresponding to each of the vaccine-induced antibodies. we followed elderly individuals residing in a nursing home, whose serum specimens were obtained before and after undergoing trivalent influenza vaccination, in ⁄ influenza season (medium-scale mixed [a ⁄ h n and b] epidemic in study area, and a ⁄ h n was circulating at the nursing home). the serum antibody titre to each strain of influenza virus was measured by the hi method, using the same antigens as those in the vaccine. all participants' body temperatures, respiratory symptoms, other general symptoms, hospitalization, discharge, and death were recorded daily from november to april in a prospective manner. when the participants suffered any influenzalike symptoms, such as sudden fever ‡ ae °c, throat swabs were collected and tested using a rapid diagnosis kit for influenza, which utilizes an immunochromatographic method. the adjusted odds ratios (or adj ) for febrile illness and kit diagnosed influenza were evaluated using multiple logistic regression models adjusting for possible confounders (i.e., age, sex, coexisting conditions, and vaccine strains). after vaccination, the proportion of subjects achieving an hi antibody titre ‡ : (seroprotection level) were ae % ( ae - ae %) for a ⁄ h n , ae % ( ae - ae %) for a ⁄ h n , and ae % ( ae - ae %) for b. during the follow-up period, the a ⁄ h n strain was isolated therein, and subjects experienced sudden-onset fever ( ‡ ae °c), and eight subjects were positive for rapid diagnosis kit. patients with a seroprotection level of the hi antibody titre ( ‡ : ) had lower incidences of febrile illness (or adj , ae ; % ci, ae - ae ) and rapid kit diagnosed influenza (or adj , ae ; % ci, ae - ae ) than those with a lower titre. thus antibody efficacy ( ) or adj ) against fever related to a ⁄ h n and kit diagnosed influenza were both estimated to be %. although statistical significance was not detected due to limited sample size, these results lend support for the usefulness of antibody efficacy. some data presented within this manuscript was also published in hara et al. asia via a regional network from which epidemics in the temperate regions were seeded. the virus isolates obtained from nasopharyngeal swab specimens from outpatients were typed and subtyped by the hemagglutination (ha) inhibition assay. the emergence of a ⁄ fujian ⁄ ⁄ coincided with higher levels of influenza-like illness in korea than what is typically seen at the peak of a normal season. most of the intermediates and fujian-like strains were isolated from asian countries, and the mutational events associated with the fujian strains took place in asia. closely dated phylogeny from december , to august , showed that the antigenic evolution of the h n fujian strains had periods of rapid antigenic changes, equivalent to amino acid changes per year ( figure ). the fujian-like influenza strains were disseminated with rapid sequence variation across the antigenic sites of the ha domain. the antigenic evolution of the fujian strains was initiated by exceptionally rapid antigenic change that occurred in asia, which was then followed by relatively modest changes. some of the data presented in this manuscript was previously published in kang et al. we compared reactivity to the novel virus strain using haemagglutination inhibition (hi) assays performed on discarded plasma specimens left over from routine testing. samples were taken from healthy adult blood donors (> years) before and after the ph n influenza epidemic that occurred during the southern hemisphere winter of , and again prior to onset of the southern hemisphere influenza season. reactivity to the novel h n strain of influenza was relatively uncommon among the healthy adult population during the first australian winter wave, rising from a baseline of % to %. a further increase in the seropositive proportion from % to % was observed over the summer months, most likely attributable to immunisation. this level of immunity appears to have been sufficient to constrain the winter epidemic. together with a final serum collection, planned for late , these data will aid evaluation of the extent and severity of disease in this 'second wave' of ph n . assessment of the extent of disease due to novel influenza a(h n ) virus (ph n ) during the winter outbreaks in australia was made difficult by the generally mild nature of disease. the epidemic was experienced in a staggered fashion around the country, reflecting the considerable geographical distances between state and territory capital cities ( figure ). differences in the intensity of case-finding during the evolving pandemic response and between jurisdictions hindered comparisons of disease burden in distinct geographical regions. rates of reported hospitalisations and deaths appeared fairly similar across states but, without a consistent exposure denominator, assessment of relative severity was difficult. we conducted a national serosurvey of antibody to ph n using residual plasma from healthy blood donors collected before and after the epidemic to estimate ph n exposure. here we report the findings of that first collection, together with new data on seroprevalence of ph n antibody in specimens gathered in march-april . these latter samples were collected prior to onset of seasonal influenza activity to assess the impact of a national ph n vaccine program conducted in spring ⁄ summer ⁄ on the proportion of individuals with antibody titres deemed protective. findings informed estimates of population susceptibility to ph n prior to the influenza season and provided a baseline for a subsequent serosurvey that will be collected at the end of to assess the extent of exposure during the 'second wave.' tralian red cross blood service (the blood service) for dengue fever surveillance studies. these samples were used to provide a baseline estimate of prevalence of cross-reactive antibody to ph n in the australian population. discarded plasma specimens, taken for virologic testing from healthy adult blood service donors, were prospectively collected at two additional timepoints for measurement of antibody to ph n . collection periods were as follows: approximately plasma samples were randomly selected from donors in each of brisbane, hobart, melbourne, newcastle, perth, sydney, and townsville on each occasion. up to specimens were identified in each of the following age strata: - , - , - , - , - , and > years. at the last collection timepoint, there was deliberate over-sampling of the oldest and youngest age strata in which approximately specimens were collected (i.e., up to specimens per site). in accordance with the provisions of the national health and medical research council's national statement on ethical conduct in human research, individual consent was not required for use of these specimens, given the granting of institutional approval by the blood service human research ethics committee. reactivity of plasma against ph n was measured in haemagglutination inhibition (hi) assays using turkey red blood cells (rbc). egg-grown a ⁄ california ⁄ ⁄ virus was purified by sucrose gradient, concentrated and inactivated with b-propiolactone, to create an influenza zonal pool preparation (a gift from csl limited). plasma samples were pretreated with receptor destroying enzyme ii (denka seiken co. ltd), : (volume ⁄ volume) and tested as previously described. following hour incubation, ll % (volume ⁄ volume) of rbc was added to each well. hi was read after minutes. any samples that bound to the rbc in the absence of virus were adsorbed with rbc for hour and reassayed. samples in which background activity could not be eliminated by these means were excluded from the analysis. titres were expressed as the reciprocal of the highest dilution of plasma where haemagglutination was prevented. a panel of control sera and plasma samples was included in all assays. it comprised paired ferret sera pre-and postinfection with the pandemic virus or seasonal influenza a(h n ), a(h n ), or influenza b viruses and paired human plasma and sera collected from donors before april or after known infection with the pandemic virus or after immunisation with the australian monovalent pandemic vaccine. all assays were performed by the who collaborating centre for reference and research on influenza. for each of the three study timepoints and within each age group, the proportion of seropositive individuals (hi titres ‡ ) was calculated, with exact (clopper-pearson) confidence intervals. the contribution of individual variables (age, gender) and location to seropositive status was assessed in separate multivariate logistic regression models developed to assess the post-pandemic and pre-influenza season collections. all statistical analyses were conducted in stata . locations of specimen collection are shown in figure , together with the number of samples tested from each centre. samples with high background hi titres or discrepancies between assays were excluded at each timepoint as follows: at baseline, from the post-pandemic collection, and in early . pared with baseline was % overall, rising from % to % (table ). the only jurisdictions in which seropositive proportions were higher in october ⁄ november than in the baseline collection were hobart [ % ( % ci ae , ae )], perth [ % ( ae , ae )], and sydney [ % ( ae , ae )]. in the multivariate regression model, the only jurisdiction in which exposure appeared somewhat higher than the reference population of brisbane was hobart [or ae ( % ci ae , ae ), p = ae ]. a marked age effect on antibody status was observed at this timepoint, with an increase in the proportion of seropositive individuals in relation to the baseline collection only noted for those aged between and years (table ) . according to the multivariate model, the youngest and oldest cohorts had similar titres, with all other groups showing significantly lower seropositive proportions than the reference population of - years [e.g. - years or ae ( % ci ae , ae , p < ae )]. an overall increase in the seropositive proportion from % to % was observed between october and april , distributed throughout all jurisdictions ( ( , ) ]. antibody titres prior to the influenza season rose in all age groups, but remained significantly lower among [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] year olds than in the youngest age cohort (table ) . adjusted ors for the seropositive proportion in the multivariate model in these age groups were: - years [or ae ( % ci ae , ae )]; - years [or ae ( ae , ae )]. the relatively low titres observed in these groups reflected small incremental increases in the seropositive proportion across each of the time points studied, suggestive of both low rates of infection and vaccination. the rise in immunity observed across the population was most likely attributable to immunisation in the majority, given the absence of observed outbreaks and very few notified cases of ph n during the period between the two plasma collections. this study suggests that, while adult exposure to ph n during the southern hemisphere winter was uncommon at around %, vaccine uptake in the australian population over the period november -may was in the order of %. this latter estimate is in keeping with recently published figures for adult ph n vaccine coverage from a national immunisation survey conducted by the australian institute of health and welfare. in that survey, vaccine coverage was significantly higher in tasmania than in other states, but mostly in those over years of age, possibly in a subgroup whose health status may have differed from that of the donor population. no allowance has been made in this analysis for likely waning of natural or vaccine induced immunity, possibly resulting in lower estimates of natural and ⁄ or vaccine exposure than may have occurred over the period. regardless of such intervening processes, the seropositive proportion among australian adults at the start of the winter season appeared likely to be sufficient to constrain transmission of infection in the age groups tested. this assertion has been borne out in practice, with only modest levels of influenza reported during the late and protracted season. a final serum collection is planned for the end of the influenza season in australia from which to assess the level of exposure in relation to the baseline observed here. the need for epidemiologic studies such as this has been highlighted by groups such as the european centre for disease control to aid evaluation of the extent and severity of the 'second wave,' known to be variable from historical reports of past pandemics in disparate populations. in - , the first wave of the swine-origin novel h n flu (h n ) pandemic swept across the world, including japan. to examine the epidemiological nature of this novel infectious disease among school children within and among small regional communities, we have carried out a complete survey on the incidence of h n among school children using absentee reports provided by school health teachers in two small administrative districts (population: about in total) in japan. we then examined the epidemiological diversity on the inci-dence of h n within and among small regional communities. we investigated seventeen elementary and ten junior high schools in moroyama-town and sakado-city located in the central part of saitama prefecture. populations are: all ages, and ; elementary schools, and ; junior high schools, and , respectively. the number of school children in each school ranges from to . the surveillance system was built on an apache-and mysql-based web server using html, php, and java-script. school health teachers enter information on children absenteeism due to school infectious diseases via web browsers at each school infirmary on a daily basis. in addition to the trend graphs shown on the web browser, detailed analyses were reported to the schools and local educational boards weekly. the basic reproduction number (r ) of h n was estimated according to becker. agentbased modeling and simulations were also performed using a multi-paradigm simulator anylogic version . (xj technologies, st. petersburg, russia). by the end of march , cumulative incidence (ci) of h n among school children in moroyama and sakado reached % and %, respectively. the overall r among school children in this area was ae . vaccination rate of children in this area during the surveillance period was reported to be very low (< %). there was no considerable difference between the epidemic curves in this neighboring town and city. on the other hand, in the individual schools, the cis as of the end of march scattered from % to % ( figure ) even though the schools are closely located. to examine the cause of this diversity, we built an agent-based community model consisted of the same numbers of agents as those of children in the actual schools and people in moroyama and sakado to simulate the infection. the ratio of probability of infection in schools and the remaining places were assumed to be : or : . using a heuristic optimization scheme, we estimated the parameters for the simulations to give the overall ci of % (the ci as of the end of march ). we then performed simulations repeatedly. the cis obtained with the repetitive simulations with the assumption of higher probability of infection in schools scattered from % to %, indicating that the cis of the small population communities may vary considerably, even though all the agents were assumed to have the same susceptibility to infection at the beginning, and the other conditions were the same. the policies for surveillance ⁄ analyses ⁄ prevention of communicable diseases in local communities have generally been decided on governmental-and ⁄ or each local administrative district-basis (populations: several hundred thousands to several millions) in japan. we found the considerable variations in the cis of h n for children among much smaller areas, i.e., the school districts (populations: all ages, several thousands; school children, several hundreds). we thus conclude that the granularity of surveillance ⁄ analyses ⁄ prevention should be finer than in the past to achieve the most effective policies against influenza and similar communicable diseases in the local communities. the cause of this diversity can be explained in part by the stochastic nature of infection transmission processes in the small populations shown by the agent-based simulations. we have already conducted a complete questionnaire survey for the school children and their parents to clarify the relevance of the other issues including differences in environmental factors, preventive policies (e.g., vaccination, school closures), etc., in each school. the detailed analyses will be reported elsewhere. a www-based surveillance system for transmission of infectious diseases among school children within and among small regional communities. j epidemiol ; (s ):s . this study confirms previous findings that age, pandemic influenza vaccination, and history of ili are associated with elevated post-seasonal gmt. this study also shows that seasonal influenza vaccination may have contributed to an increase of the hai titer, especially in the elderly. further analyses in this cohort are needed to confirm and explain these first results. the follow-up of subjects involved in the copanflu-france cohort will provide data to study the risk factors for infection by the influenza virus. the first cases of the a ⁄ h n v pandemic influenza were reported in mexico and the united states in april . given the context of this new influenza virus and considering the likelihood of its pandemic spread, the cohorts for pandemic influenza (copanflu) international consortium was created in order to study individual and collective determinants of pandemic a ⁄ h n v influenza across different countries by setting up prospective cohorts of households, followed during years. this study relies on the first available data from the copanflu-france project, which is part of the copanflu international consortium. we studied factors associated with elevated haemagglutination antibody titers against a/h n v at entry in the copanflu-france cohort. we focused in this primary analysis on the association between the titers and influenza vaccination (seasonal or pandemic) across age groups. the copanflu-france cohort was set up in fall . inclusions began on december , and ended on july , . households were sampled using a random telephonic design (mitofsky-waksberg method) in a stratified geographical sampling scheme, aimed at including a sample of subjects representative of french general population. all household members were eligible to the cohort, without any age limit. the inclusion of a household required the participation of all members: the refusal of one or more member(s) prevented the inclusion of other members. the protocol was approved by a research ethics committee and written informed consent was obtained for all subjects. this study requires several visits to the households by nurses who collect written data with questionnaires and biological samples. during the inclusion visits, nurses collected from all subjects detailed data regarding medical history, including vaccination and preventive measures against influenza. blood samples were collected at entry and centralized. a standard hai technique was adapted to the detection and quantification of antibodies to the a ⁄ h n v virus. the titration endpoint was the highest dilution that exhibited complete inhibition of haemagglutination in two independent readings. the lowest read dilution was ⁄ . geometric mean titers were calculated for hai assays with the use of generalized estimating equations for interval-censored data, , taking into account a within-household correlation. multivariate models were derived from this method to identify factors associated with elevated gmts. we defined the ''gmt ratio'' (gmtr) as the multiplicative factor applied to the gmt in presence of an explanatory variable. for qualitative explanatory variables, a gmtr of n means a predicted n-fold higher gmt for subjects exposed to the considered factor compared to others. for continuous explanatory variable, the same interpretation applies to a unit difference. the following variables were included in the multivariate models: age, history of pandemic or seasonal influenza vaccination, and history of ili. age was categorized in three groups: - years (reference group), - years and over years. the definition of ili was that used by the cdc : fever ‡ ae °c and cough and ⁄ or sore throat without another known cause. history of ili was defined as an ili reported by the subject between september , (beginning of the influenza epidemic in france) and the date of inclusion. this preliminary analysis included subjects belonging to households. results reported hereafter do not account for missing data. participating households were sized - subjects, mean size = ae . in comparison, the mean size of french households is ae according to the latest national census. the median age of subjects at entry was ae years [iqr: ae ; ae ] versus ae [ ae ; ae ] for french population. the proportion of subjects reporting a history of ili since the beginning of the epidemic varied from ae % for subjects over years to ae % for subjects below years (table ) . vaccination with the pandemic strain was the highest in subjects below ( %) whereas vaccination with the seasonal strain was the highest in subjects over ( ae %). detailed data regarding vaccination is given in table . this study confirms previous findings that age, pandemic influenza vaccination, and history of ili are associated with elevated post-seasonal gmt. [ ] [ ] [ ] [ ] [ ] [ ] among non-vaccinated subjects, elevated gmt in the elderly may be the result of exposure to similar viruses in early life, whereas children and young adults with elevated gmt are likely to have been infected by the a ⁄ h n v virus. [ ] [ ] [ ] [ ] interestingly, a significant drop in the hai titer is observed during the months following vaccination with the pandemic strain. this study also shows that seasonal influenza vaccination may have contributed to an increase of the hai titer, especially in the elderly. the reason for this association is not obvious: although we cannot discard the hypothesis of a higher incidence of a ⁄ h n v infections in seasonal vaccine recipients, as described by several other studies, - the main explanation may be a cross-reaction between pandemic and seasonal strains. , , further analyses in this cohort are needed to confirm and explain these first results. the follow-up of subjects involved in the copanflu-france cohort will provide data to study the risk factors for infection by the influenza virus. in april , the cdc alerted about the appearance of a new strain of ia h n with unknown virulence. infants under years old had higher risks of hospitalization, complications, and rate of death for sari. materials and methods: a cross-sectional study was executed from may to december in . the sources were: mandatory reporting form of the province surveillance system, databases of the hospital management information system, clinical pictures reviews, and telephone daily medical reports. inclusion criteria: children under years old with diagnostic of ili or sari and confirmed cases with epidemiological nexus or laboratory confirmation (rrt-pcr, ifi). the age specific mortality rates were calculated with an estimated population for the province according to the national statistics and census institution. results: the ili rate in infants under years old was ae ⁄ people ( % ci - ) being higher in infants of years old ( ⁄ people of years ( % ci - ) ( table ) . infants had less risk of getting sick in relation to the rest of the population (rr ae [ % ci ae - ae ]) (p < ae ). the chance of sari in infants was ae ( % ci ae - ae ) compared to the rest of the population. the lethality rate was higher in infants under year old ( ⁄ people [ ⁄ ]). discussion: the evidence suggests that the infants under years old had lower risk of getting sick than the rest of the population, but had higher risk of sari if they had some past illness. the highest lethality rate was presented in infants under year old. non-medical interventions had an important role in the epidemic containment for not having a specific vaccination available. as this age group had high risks of hospitalization, it would be advisable to prioritize their vaccination. in april , the cdc alerted about the appearance of a new strain of ia h n with unknown dissemination and virulence. in june, the world health organization declared the pandemic. , the ili often presents an unspecific clinical picture in infants under years old, from mild symptoms to sari, especially in the newborn babies. infants under years old have higher risks of hospitalization, complications, and rate of death for sari. , on may th, argentina declared the first imported case of ia h n , and by the end of the month, it announced the viral circulation in the country. the epidemiological surveillance system of the province arranged that all the patients with influenza diagnosis made by a doctor must be reported. from april th to november th, suspected cases of ili in the province of tucumán were reported. the ili rate was ⁄ people, and ia h n comprised ⁄ people. the lethal rate of sari ia h n was ae ⁄ people ( ⁄ ). the objective of this research was to determine the epidemiological characteristics of the pandemic ia h n in infants under years old in the province of tucumán between may and december in . the province of tucumán is placed in the center of the northwest of the republic of argentina. it has a population of inhabitants of which are infants under years old. the crude birth rate for was ae &. the infant mortality rate was ae &. respiratory pathologies in infants under years old were the third cause of death in the province ( %). the public health system of the province is composed by three sectors: public, private, and welfare. with health facilities as a total, the average of available beds is & per inhabitants and & per neonates. a cross-sectional study was executed from may to december in in the province of tucumán, argentina. the following sources were used: mandatory reporting form of the surveillance system of the province filled by a doctor, databases of the hospital management information system, clinical pictures reviews, and telephone daily medical reports (patients with sari). inclusion criteria: • suspected case of ili: sudden appearance of fever higher than °c, cough, or sore throat. it may or may not be accompanied by asthenia, myalgia or prostration, nausea or vomiting, rhinorrhea, conjunctivitis, adenopathy, or diarrhea. ) were used for the analysis. the odds rations, risk ratio and % confidence interval were calculated to compare ambulatory with hospitalized patients, confirmed and dismissed, < years old and the rest of the population. it was considered significant a rate of p < ae . the age specific mortality rates were calculated with an estimated population for the province according to the national statistics and census institution. the epidemiological surveillance system of the province received ili reports, ae % ( ⁄ ) were infants under years old. twenty seven percent were dismissed ( ⁄ ), and % ( ⁄ ) of suspected cases were confirmed. the first ia h n case was a child of years from the province of buenos aires, in th epidemiological week, and the last suspected case was reported in october , ( figure ). the ili rate in infants under years old was ae ⁄ people ( % ci - ), being higher in infants of years old ( ⁄ people of years, [ %ci - ]). the higher ili rates in confirmed the pandemic of ia h n ( ) was detected for the first time in the province of tucumán. the evidence suggests that infants under years old had lower risk of getting sick than the rest of the population (protective factor), but had higher risk of sari if they had some past illness. the highest lethality rate was presented in infants under year old. towns with the highest demographic density had superior proportion of cases. non-medical interventions had an important role in the epidemic containment for not having a specific vaccination available. as this age group had high risks of hospitalization, it would be advisable to prioritize their vaccination. outbreak of h n influenza - : behavior of influenza h n in school children in the province of tucumá n, argentina criteria: patients treated with antiviral medication for prophylaxis, respiratory pathologies which did not justify specific medication, and incomplete forms. results: from all notifications, were cases of ili in the group aged - years old; % were males. the incidence rate in this group was ae per thousands of inhabitants. the % of laboratory samples were influenza a h n , % were confirmed as unspecific influenza, and % were dismissed. the school aged children group had a high risks of getting sick (r.r. ae [ % c.i. ae - ae ]), especially males. it appeared that school aged children had a protective factor for presenting sari (or ae [ % c.i. ae - ae ], p < ae ). the lethality rate in this group was ae ⁄ thousands. headaches, myalgia, coryza, and sore throat were very common and significantly different (p < ae ) than the rest of the population. it was reported a decrease in the ew coinciding with winter holidays (ew ). the epidemic curve was different in males compared to females during the winter holidays. discussion: school aged children got sick more than the rest of the population, although they presented less proportions of sari. however, comorbidities were decisive in order to present sari or death. the epidemic curve was different in males compared to females. through its analysis, the beneficial effect of school closure was observed, as long as children meet the recommendation to stay home. in april , different countries reported cases of influenza a h n ; mexico reported a high mortality rate associates with this disease. the world health organization (who) declared the phase influenza pandemic alert on june . several reports from different countries describe the behavior of the pandemic in school aged children. this group plays an important role in the transmission of influenza. in germany, during the summer peak, pandemic hardly spread within this group. this might be explained by the timing of the summer school holidays, which started between ew and . since mid october, after the autumn holidays, the school-aged children began to be more affected, and the proportion increased from % in the initiation period to ae % in the acceleration period. in australia, % of h n cases were school aged children ( - years), with a median age of years ( % of cases were aged - years and, and % between - years). in canada, the infection rate was highest in this group. in chile, the incidence rate was ⁄ inhabitants, although in general they had mild desease. school closure can operate as a proactive measure, aimed at reducing transmission in the school and spread into the wider community, or reactive, when the high levels of absenteeism among students and staff make it impractical to continue classes. the main health benefit of proactive school closure comes from slowing down the spread of an outbreak within a given area and, thus, flattening the peak of infections. this benefit becomes especially important when the number of people requiring medical care threatens to saturate health care capacity. it has its greatest benefits when schools are closed very early in an outbreak, before % of the population falls ill. school closure can reduce the demand for health care by an estimated - % at the peak of the pandemic under ideal conditions, but too late in the course of a community-wide outbreak, the resulting reduction in transmission is likely to be very limited. policies for school closure need to include measures that limit contact among students when they are not in school. tucumán is placed in northwest argentina and has a total area of km . the population ( census, projection ) was inhabitants; of wich were - years old. the health system of the province is composed of sectors: public, private, and welfare. it has a total of health facilities with internement available and an average of & inhabitants. influenza-like illness (ili) has seasonal and endemic behavior in this province, as evidenced by past records from the national health surveillance system and influenza sentinel surveillance unit of the province. an increase of ili was reported in , with a peak in the ew . the objectives were: general objective to describe the behavior of the influenza a h n epidemic in school aged children from the province of tucumán, argentina. specific objectives • to explore the response to preventive measures by school aged population. • to assess the effect of the suspension of classes in this group. • to estimate the magnitude and severity of the disease. • to observe the effect of co-morbidities in this group. a cross-sectional study was executed from may to december . data were gathered through mandatory reporting forms, wich were collected from all public and private health centers. inclusion criteria: patients with compatible symptoms with influenza a; school aged children - years old. exclusion criteria: patients treated with antiv- iral medication as prophylaxis, respiratory pathologies which did not justify specific antiviral medication, and incomplete forms. • suspected case of ili: cases considered by clinical criteria (fever higher than °c, cough or sore throat. it may or may not be accompanied by asthenia, myalgia or prostration, nauseas or vomiting, rhinorrhea, conjunctivitis, adenopathy, or diarrhea). • confirmed case: person with positive laboratory results for influenza a h n or unspecificed influenza a (by laboratory results through rrt-pcr or immunofluorescence techniques). • dismissed case: by negative or different laboratory results, or different clinical evolution. • comorbidities: chronic illnesses like arterial hypertension, diabetes, asthma, recurrent obstructive bronchial syndrome (robs), smoking, chronic obstructive pulmonary disease (copd), immunosuppression, hiv ⁄ aids, cancer, nephropathy, obesity; pregnancy was also considered. data were analyzed using epi software (epi infoÔ cdc, atlanta, eeuu). rates were calculated and rr was estimated with their respective confidence interval (ci). population data were taken from national census projections. an estimation based on the same census was used for the group between and years old. to observe the effects of other co-variables, the or and their ci were calculated. logistic regression was used to evaluate the influence of the comorbidities. x was used to compare proportions. respiratory samples (nasopharyngeal and faryngeal swabs) were obtained. they were analyzed at influenza sentinel surveillance unit of tucumán, and ⁄ or sent to national reference laboratory dr. c. malbrán (rt-pcr). from all notifications ( ), were cases of ili in the group aged between and years old, % ( ⁄ ) of which were males. the incidence rate was ae , and it differed according to the sexes: ae males and ae females per thousands of inhabitants (p < ae ). of all laboratory samples ( ) % were confirmed as influenza h n , % were confirmed as unspecificied influenza, and % were dismissed. the remaining percentage corresponded to the isolation of other viruses (parainfluenza, respiratory syncytial virus, and adenovirus). the school aged group had higher risk of getting sick, in relation to the rest of the population (rr ae [ % ci ae - ae ]), especially males (rr ae ) compared with females (rr ae ). the highest attack rate was observed in the capital of tucumán ( ⁄ inhabitants). according to the rest of the population, it looked like being school aged children meant a protective factor for presenting sari (severe acute respiratory infection) (or ae [ % ci ae - ae ], p < ae ). the lethality rate was ae ⁄ thousand. the risk of dying was low compared to other ages. persons with comorbidities had significantly higher risk of presenting sari (or ae [ % ci ae - ae ], p < ae ) and of dying (or ae [ % ci ae - ae ], p < ae ). respiratory comorbidities were the most fre- quent: asthma ae % ( ⁄ ) and % rors ( ⁄ ). the symptoms headaches, myalgia, coryza, and sore throat were very common and significantly different (p < ae ) than the rest of the population. if we compared the group aged - years with - years old, the epidemic curve of the first group showed a decrease in the ew , coinciding with winter holidays (ew ) (figure ). there was a slight increase in the tendency when classes began, but it showed a clear declination afterwards. the analysis of rates in school aged children by ew showed a reduction of ae % in males and ae % in females (p < ae ) at ew . however, after the first week of winter holidays, the curve in males had a significant increased to ae % compared to ew , reaching the highest weekly rate of the epidemic ( ⁄ inhabitants). the reopening of classes coincided with a significant decrease of the rate ( ae %), from to ae ⁄ inhabitants in ew (p < ae ). in females, the school closure coincided with a plateau-shaped curve, and the reopening with a significant decrease of ae % of the rate, from ae to ae in ew ( figure ). the school children got sick a lot more than the rest of the population, although they presented less proportions of sari. however, comorbidities were determined in order to present sari or death. symptoms like headache, myalgia, coryza, and sore throat were considered more conducting for the definition of cases in this population in tucumán. the epidemic curve was different in males compared to females during the winter holidays. the beneficial effect of school closure was observed as long as persons met the recommendations. the difference between males compared to females during winter holidays could mean that women would have carried out social distance recommendations much better, for example, remained at home. the significant reduction after the opening of classes is a factor to be considered as an effective intervention in the declining stage of the curve. here, we report pdmh n infection attack rate (iar) during the first wave of the pandemic. we used our iar estimates to infer the severity of the pandemic strain, including the age-specific proportion of infections that led to laboratory confirmation, hospitalization, intensive care unit (icu) admission, and death. [ ] [ ] [ ] [ ] part of these results are now available in ref. subjects of a community study, - years old between november and october , we conducted a cohort study of pediatric seasonal influenza vaccination and household transmission of influenza. one hundred fifty-one children aged - were recruited and provided baseline sera in november and december . between september and december a further children aged - were recruited and provided baseline sera for the second phase of the study. for this serologic survey, we tested the sera collected before the first wave and the sera collected after the first pandemic wave. written informed consent was obtained from all participants. parental consent was obtained for participants aged or younger, and children between the ages of and gave written assent. all study protocols were approved by the institutional review board of the university of hong kong ⁄ hospital authority hong kong west cluster. age-stratified data on virologically confirmed outpatient consultations, hospitalizations, icu admissions, and deaths associated with pdmh n from april to november were provided by the hong kong hospital authority (the e-flu database). since may , patients admitted with acute respiratory illnesses routinely underwent laboratory testing for pdmh n virus by molecular methods. sera were tested for antibody responses to a ⁄ california ⁄ ⁄ by viral microneutralization (mn). most individuals infected with influenza develop antibody titers ‡ : by viral microneutralization after recovery. we defined the pdmh n seroprevalence rate as the proportion of individuals who had antibody titers ‡ : . while mn antibody titers of ‡ are not by themselves conclusive evidence for pdmh n infection, we have assumed that the increase in cross-sectional seroprevalence between the pre-and post-first wave time periods are evidence of recent pdmhn infection. the iar was defined as the proportion of individuals infected by pdmh n during the first wave. the case-confirmation rate (ccr), case-hospitalization rate (chr), case-icu-admission rate (cir), and case-fatality rate (cfr) were defined as the proportion of pdmh n infections that led to laboratory-confirmation, hospitalization, icu admission, and death. due to containment efforts until june , all laboratory-confirmed cases were required to be hospitalized for isolation regardless of disease severity. as such, only surveillance data from june onwards were used to estimate severity measures. we estimated the iar as the difference between the prefirst-wave and post-first-wave seroprevalence rate. we used the estimated iar as the denominator for calculating the ccr, chr, cir, and cfr. we used an age-structured sir model with age classes ( - , - , - , - , and ‡ ) to describe the transmission dynamics of pdmh n in hong kong between june and november . we assumed that the mean generation time was ae days. using the age-structured transmission model, we estimated the following transmission parameters from the serial cross-sectional serologic and hospitalization data: (i) r o , the basic reproductive number; (ii) p and p , the reduction in within-age-group transmission for - and - years old during summer vacation (compared to school days during september-december ); (iii) d r , the average time for neutralization antibodies titer to reach ‡ : after recovering from infection; (iv) h a , the age-specific relative susceptibility with - years old adults as the reference group. we assumed non-informative priors for all parameters and used monte carlo markov chain methods to obtain posterior distributions of the parameters. sources of specimens: [ ] pediatric cohort study ( - april virological surveillance data suggested that the first wave of pdmh n in hong kong occurred from august to october . most of the laboratory-confirmed infections in this first wave occurred in individuals aged below years old accounting for > % of the lab-confirmed cases and hospitalizations, % of icu admissions, and % of deaths. taking into account a delay of - weeks for antibody titers to appear during convalescence, we found that these virological surveillance data were consistent with our serial cross-sectional seroprevalence data, which indicated a sharp rise in seroprevalence among the - years old from september to november and a plateau thereafter (data not shown). among individuals aged - years, the seroprevalence rates were similar across time between pediatric outpatient subjects and pediatric cohort study subjects (data not shown). similarly, for older age groups, the seroprevalence rates were largely similar between blood donor subjects and hospital outpatient subjects (except for the - years old in november-december). this provided some evidence that despite biases in our convenience sampling scheme, the resulting serologic data provided a reasonably representative description of seroprevalence in the community. the estimated pre-and post-first-wave seroprevalence rates and the corresponding iar estimates are shown in table . the severity estimates (ccr, chr, cir, and cfr) are shown in table . in summary, we estimated the iar was ae % among - years old, ae % among - years old, ae % among - years old, ae % among - years old, ae % among - years old, and ae % among - years old. overall, we estimated a population-weighted iar of ae % ( - %) among individuals aged - years through the first wave in hong kong. ccr were around ae - ae % among the - years old. chr were around ae - ae % among the - years old. cir increased from ae ( ae - ae ) per infections in - years old to ( ae - ) per infections in - years old. cfr followed a similar trend with ae ( ae - ae ) death per infections in - years old to ae ( ae - ) deaths per infections in - years old. compared to children aged - , adults aged - were ae and times more likely to be admitted to icu and die if infected. the best-fit age-structured transmission model gave the following parameter estimates: . the basic reproductive number was ae ( %ci, ae - ae ). . it took an average of ( - ) days for recovered individuals to develop neutralization antibody titer ‡ : . table . estimated age-specific proportions of individuals with pdmh n infections that were laboratory-confirmed, were hospitalized, were admitted to icu, and died. case-icu and case-fatality rates are expressed as number of episodes per infections . compared to - years old, - years old children and - teenagers were ae ( ae - ae ) and ae ( ae - ) times more susceptible to pdmh n infection, respectively. . compared to - years old, - years old older adults and - years old elderly were only ae ( ae - ae ) and ae ( ae - ae ) times as susceptible as the - years old, respectively. . compared to the school period during september-december , summer vacation reduced within-agegroup transmission by % ( - %) among - years old, but only % ( - %) among - years old. using computer simulations, we estimated that if preexisting seroprevalence is zero, real-time serologic monitoring with about specimens per week would allow accurate estimates of iar and severity as soon as the true iar has reached % (data not shown). we estimated that during the first wave in hong kong, ae % of school-age children and ae % of individuals aged - were infected by pdmh n . a serologic survey in england found similar iars in london and the west midlands. both studies highlight the importance of including serologic surveys in pandemic surveillance. the geographically compact and well-mixed population in the urban environment of hong kong permits some degree of confidence in the validity of our iar and severity estimates. the completeness of the pdmh n surveillance system, welldefined population denominator, and our large-scale serologic survey provide accurate numerators and denominators for the severity measures. we based severity estimates for pdmh n on the iar as the denominator. in most previous studies of pdmh n severity, the denominator was clinical illness attack rate, which depends on the probability of symptoms as well as medical care seeking behavior of the population. , our estimated cirs and cfrs are broadly consistent with presanis et al.'s 'approach ' severity estimates, but around - times lower than their 'approach ' estimates. our estimates of chr are - times higher than their approach estimates of symptomatic chr. however, the hospitalization-death ratio was ⁄ = as of november in hong kong, but ⁄ = as of june in new york, suggesting that the clinical threshold for admission in terms of disease severity at presentation may have been lower in hong kong. our study has a number of limitations. first, we have used antibody titers of ‡ : by viral microneutralization as an indicator of recent infection, correcting for pre-existing seroprevalence levels, but this may lead to underestima-tion of the iar if some infections led to antibody titers < : , or if some individuals with baseline titers ‡ : were infected. second, our estimates of the iar would be biased upwards if infection with other circulating influenza viruses led to cross-reactive antibody responses resulting in antibody titers ‡ : . however between august and october , % of influenza a viruses detected in hong kong were pdmh n , and only % of isolated viruses were seasonal h n viruses. third, a minority of severe illnesses associated with pdmh n infection might not be identified by molecular detection methods, for example if admission occurred after viral shedding from the primary infection has ceased, in which case we may have underestimated the disease burden of pdmh n . finally, our analyses are primarily based on seroprevalence among blood donors to the hong kong red cross, who may not be representative of the whole population. we do not have detailed data on donors to compare their risk of infection with the general population, but we did observe very similar seroprevalence rates across the three groups of subjects in our study, i.e., blood donors, hospital outpatients and participants in a community cohort (data not shown). in conclusion, around ae % of the population aged - and half of all school-age children in hong kong were infected during the first wave of pandemic h n . compared to school-children aged - , older adults aged - , though less likely to acquire infection, had ae and times higher risk of icu-admission and death if infected. thus, although the iar of pdmh n is similar to that of a seasonal epidemic, the apparently low morbidity and mortality of pandemic influenza (h n ) appears to be due to low infection rates in older adults who had a much greater risk of severe illness if infected. the reasons why older adults appear relatively resistant to pdmh n infection even though they appear to lack neutralizing antibody remains unclear. if antigenic drift or other adaptation of the pdmh n virus allows these older age groups to be infected more efficiently, the morbidity and mortality of subsequent waves of the pandemic could yet become substantial. and the national institute of allergy and infectious diseases, national institutes of health (contract no. hhsn c; adb no. n -ai- ). the funding bodies had no role in study design, data collection and analysis, preparation of the manuscript, or the decision to publish. bjc reports receiving research funding from medimmune inc., a manufacturer of influenza vaccines. the authors report no other conflicts of interest. some data presented in this manuscript were previously published in wu et al. it is well known that a primary goal of vaccination is to generate immunological memory against the targeted antigen to prevent disease in a vaccinated person. this ensures an accelerated immune response in the event of future contact with the pathogenic agent, such as a virus. therefore, it is very important to develop criteria for the assessment of vaccine immunogenicity by measuring both t and b memory cell levels from the vaccinated host. in contrast to inactivated influenza vaccines, live attenuated influenza vaccines (laivs) have been shown to provide primarily cellular and local immune responses. - to date, however, the hemagglutination-inhibition (hai) test (i.e. detection of serum antibodies) remains the method widely accepted for evaluation of an influenza vaccine's immunogenicity. improved understanding of the role of cellular and mucosal immunity and their contribution to protecting against severe illness caused by influenza infection has emphasized the need to reconsider methodologies used to evaluate the immunogenic impact of various influenza vaccines. such new assays need to include methods to measure local antibodies and virus-specific lymphocytes, especially in the case of live attenuated influenza vaccines, because of their potential to induce such broad-based immune responses. the aim of this study was to assess the ability of new russian pandemic laivs a ⁄ ⁄ duck ⁄ potsdam ⁄ ⁄ (h n ) ('ultragrivak,' registered ae ae ) and a ⁄ ⁄ california ⁄ ⁄ (h n ) ('influvir,' registered ae ae ) to induce memory t-cells in naïve human subjects and to compare results to levels of hai antibodies from each subject. a ⁄ ⁄ duck ⁄ potsdam ⁄ ⁄ (h n ) laiv was generated by : genetic reassortment of low-pathogenic avian influenza virus a ⁄ duck ⁄ potsdam ⁄ - (h n ) and master donor strain a ⁄ leningrad ⁄ ⁄ ⁄ (h n ). , the vaccine strain contains ha gene from avian virus, as well as na and internal genes from the master donor virus. a ⁄ ⁄ california ⁄ ⁄ (h n ) laiv was generated by classical ( : ) reassortment of a ⁄ california ⁄ ⁄ (h n ) with the master donor virus. the vaccine strain contains ha and na genes from a 'wild-type' h n strain and internal genes from the master donor virus. participants were aged to years and were without contra-indication of laiv vaccination. immunogenicity of a ⁄ ⁄ duck ⁄ potsdam ⁄ ⁄ (h n ) laiv was assessed in ten vaccinated persons and ten volunteers inoculated with a placebo (sterile physiological saline solution). immunogenicity of a ⁄ ⁄ california ⁄ ⁄ (h n ) laiv was estimated in vaccinated volunteers and nine volunteers inoculated with placebo. viruses or placebo were administered intranasally twice with an interval period of days at a dosage of ae ml per nostril for each vaccination. physical examination, venous blood and nasal swab samples were collected at four time points during the study: (i) before vaccination (day ); (ii) days after first vaccination (day ); (iii) days after the second vaccination (day ); and (iv) weeks after the second vaccination (day ). serum hai antibodies were measured by standard hai assay using % human red blood cells. test antigens for the assay were a ⁄ ⁄ duck ⁄ potsdam ⁄ ⁄ (h n ) or a ⁄ ⁄ california ⁄ ⁄ (h n ) to match the appropriate vaccine antigen. local iga antibodies in nasal swabs were evaluated by elisa using whole purified a ⁄ ⁄ duck ⁄ potsdam ⁄ ⁄ (h n ) or a ⁄ ⁄ california ⁄ ⁄ (h n ) viruses at hau per ae ml for absorption to elisa plates. endpoint elisa titers were expressed as the highest dilution of sera that gave an optical density (od) greater than twice the mean od of six negative controls in the same assay. percentages of virus-specific cd + cd + ifn-c + and cd + cd + ifn-c + peripheral blood memory cells were determined using a flow cytometry iccs assay performed by the published method. pbmcs were prepared with standard histopaque- gradient centrifugation from heparinized whole blood. wilcoxon matched pair test, mann-whitney u test and the students t-test were used for statistical data analysis. prior to the first vaccination (day ), gmts of hai antibodies to a ⁄ ⁄ duck ⁄ potsdam ⁄ ⁄ (h n ) and a ⁄ ⁄ california ⁄ ⁄ (h n ) laivs were ⁄ ae and ⁄ ae , respectively. in addition, gmts of siga against these specific antigens from nasal swabs were ⁄ ae and ⁄ ae , respectively. no hai antibody titers greater than : were observed prior to vaccination. background levels of virusspecific t-cells varied significantly within groups. mean levels of virus-specific cd + ifnc + cells were ae % to a ⁄ ⁄ duck ⁄ potsdam ⁄ ⁄ (h n ) and ae % to a ⁄ ⁄ california ⁄ ⁄ (h n ). for cd + ifnc + cells, initial levels were ae % and ae %, respectively. thus, background levels of virus-specific antibodies were low, but prior vaccination or virus exposure in some volunteers produced some pre-existing levels of t cells, thus they were not absolutely immunologically naïve in this sense. preexistence of h n -crossreactive antibodies and t-cells has been observed previously. [ ] [ ] [ ] effect of vaccination antibody immune responses both influenza a (h n ) and influenza a (h n ) laivs stimulated production of serum hai antibodies and local iga antibodies in nasal swabs. following the first vaccination with influenza a ⁄ ⁄ duck ⁄ potsdam ⁄ ⁄ (h n ) laiv, % percent of volunteers exhibited seroconversion of hai antibodies; after the second vaccination, % of volunteers exhibited seroconversion. after the first vaccination, a % conversion rate of siga was observed; after the second vaccination, % showed conversions in levels of siga. the first vaccination with a ⁄ ⁄ california ⁄ ⁄ (h n ) laiv showed ae % of hai antibodies seroconversions vaccination, and % seroconversion after second vaccination. for local siga, those results were ae % and ae % following the first and second inoculation, respectively. figure summarizes cellular immune responses observed in the vaccinated versus the placebo group. after the influenza a (h n ) laiv inoculation, significant differences in both cd and cd ifnc-producing t-cells were observed at day after the second vaccination (d ). these data indicate that healthy young people who never received such avian influenza vaccines and were not exposed to h n wild-type viruses were able to respond to the live attenuated h n influenza vaccine. after the first influenza a (h n ) laiv vaccination, reliable increases were observed in cd + cells only. after the second vaccination, increases in both cd + and cd + fold changes were significantly higher in vaccinated volunteers compared to the placebo group. it is noteworthy that cellular immune responses (cd + and cd + cells) were more marked in the a ⁄ ⁄ california ⁄ ⁄ (h n ). considering the long-term circulation of h -subtype viruses among humans in contrast to the novelty of h viruses, such a result would be expected. similar data were also observed following vaccination with the h n laiv. after first vaccination, the percent of people with notable increases in virus-specific cd + and cd + t-cells was % and % to h n and % and % to h n , respectively. after the second vaccination, these results were % and % to h n and % and % to h n , respectively. importantly, a significant number of vaccinated volunteers without remarkable increases ( ‡ -fold) in hai antibodies had notable increases in cd + and ⁄ or cd + memory cells. the percent of people with notable increases in virus-specific t cells after the second vaccination among hai()) volunteers was % and % to h n and h n , respectively. these results indicate that laivs were able to induce broadly responsive, key antiviral immune responses that would not have been detected by the hai assay alone. thus, it can be deduced that hai data alone fails to reveal important broad and specific immune responses to laiv. consequently, the hai test alone is not suitable for assessment of laiv immunogenicity. furthermore, vaccination with h n laiv was able to induce cross-reactive memory t-cells to a seasonal vaccine strain, a ⁄ ⁄ solomon islands ⁄ ⁄ (h n ) ( table ) . reliable increases to a (h n ) were observed in up to % of volunteers. there was an inverse dependence between levels of memory t cells before and after vaccination. authors are thankful to path for the financial support of these studies. we are also thankful to jessica d'amico and dr. rick bright for their editorial review. options for the control of influenza vii background: increased susceptibility of older populations to secondary bacterial pneumonia-like infections following influenza infection has been well documented. recent evidence in mouse models suggests that this increased risk from secondary bacterial infection occurs through a desensitization of the innate immune response. this recent finding, however, does not account for potential differences in immune responsiveness due to age. materials and methods: to address this parameter, we used three age groups (aged, adult, and young mice) to evaluate the role of age in influenza-mediated vulnerability to secondary bacterial challenge with pseudomonas aeruginosa. all mice were evaluated for multiple parameters including: (i) survival; (ii) lung bacterial load; (iii) total lung protein content; (iv) immune cell infiltration; (v) cytokine ⁄ chemokine expression; and (vi) toll-like receptor (tlr) rna expression profiles. results: prior challenge with influenza contributed to aberrant cytokine ⁄ chemokine profiles and increased lung cellular infiltrate in response to secondary bacterial infection across all age groups, supporting a critical role for influenza infection in the alteration of immune responses to other pathogens. also similar to human influenza, these changes were exacerbated by age in mice as demonstrated by increased bacterial load, mortality, and total lung protein content (an indicator of lung damage) after p. aeruginosa challenge. conclusions: these data support a potential role for virus-mediated and age-mediated alteration of innate immune effectors in the pathogenesis of influenza and the increased susceptibility of influenza virus infected mice to secondary bacterial infection. the understanding of the complex interaction of host and pathogen -and the role of age -in human influenza is critical in the development of novel therapeutics and improved vaccine approaches for influenza. our results support further examination of influenza-mediated alterations in innate immune responses in aged and non-aged animals to allow elucidation of the molecular mechanisms of influenza pathogenesis in humans. there is considerable evidence in the clinical literature to support the role of influenza infections with an enhanced risk for secondary bacterial pneumonias. [ ] [ ] [ ] given the increased pneumonia-related morbidity and mortality in both the young and elderly populations, there is rationale for gaining a deeper understanding as to the systemic changes in the pulmonary microenvironment. although there are some recent reports that account for some of the molecular mechanisms at work in this disease process, there is a paucity of experimental evidence that considers the potential effects of age. developmental changes in the immune system that occur in the aged environment have been well documented with regard to senescence of the adaptive immunity, global changes in myeloid cell function, and the establishment of a general pro-inflammatory state. , the aim of this work was to provide evidence for the contribution of the aged immune environment to the pathology of influenza mediated secondary bacterial infections. animals used in this study were housed under conditions approved by tulane university's institutional animal use and care committee. female balb ⁄ c mice used in these studies were divided into three age groups: aged ( months old), adult ( months old), and young ( months old). each age group was subdivided into two groups: influenza infected and naïve (control). mice were infected by the intranasal route with · pfu of mouse-adapted influenza a ⁄ pr ⁄ ⁄ . clinical disease was measured by body weight changes over a week period post influenza challenge, and recovery was determined as return to pre-infection weight. all mice were subsequently challenged intransally with · cfu pseudomonas aeruginosa strain pao . twenty-four hours post-pseudomonas challenge, bal with sterile pbs was performed on all mice in all groups. total rna from the cellular fraction was pooled from three experimental animals from each group. tlr mrna was detected by qrt-pcr, where expression levels were determined as relative to b-actin mrna levels. cdna was synthesized from total cellular rna from bal samples using iscript cdna synthesis kit (biorad). pcr reactions were composed of ae lg cdna forward and reverse primers according to optimized conditions and ae ll of · syber green icycler supermix (biorad), in a total vol-ume of ll and were run using a biorad icycler utilizing melting point determination. primers and concentrations used in this study included: mus_tlr f: tgctttcct-gctggagattt- nm, mus_tlr r: tgtaacgcaac agcttcagg- nm, mus_tlr f: atatgcgcttcaa tccgttc- nm, mus_tlr r: caggagcatactggt gctga- nm, mus_tlr f: ggcagcaggtggaattg tat- nm, mus_tlr r: aggccccagagttttgttc t- nm, mus_tlr f: ctggggacccagtatgctaa- nm, mus_tlr r: acagccgaagttccaagaga- nm, mus_tlr f: ggagctctgtccttgagtgg- nm, mus_tlr r: caaggcatgtcctaggtggt- nm, mus_ b-actinf: agccatgtacgtagccatcc- nm, mus_b-actinr: ctctcagctgtggtggtgaa- nm. as a measure of protein leakage into the alveolar space, total protein content in each bal was measured by bca assay of each supernatant fraction according to manufacturer's instructions (pierce). cytokine and chemokines levels were measured by multiplexed bead array (bioplex, biorad). immune cell characterization of bal was estimated by flow cytometry. lymphocyte populations were gated by forward versus side scatter and characterized as b cells (f ⁄ ) , cd + ) or t cells (cd b ) , cd + ). the myeloid population that is composed of macrophages, neutrophils, dendritic cells, and natural killer cells was enumerated by gating all but those found in the lymphocyte gate using forward versus side scatter plots. flow cytometry data was analyzed using flojo software (treestar). statistical analysis, where appropriate, was performed using a two-way analysis of variance (age versus influenza infection status) supported by bonferonni's correction for multiple comparisons. a recent finding by didierlaurent, et al., described an influenza mediated desensitization of tlr function as a primary contributor to an increase in bacterial burden when challenged after resolution of the primary influenza infection. this finding, however, was obtained using animals that were - weeks of age, where our study included two cohorts of older mice ( months and months). using whole protein content of the bal as an estimate of protein leakage into the lumen of the lung, we found elevated protein content in aged mice as compared to young and adult mice. in aged mice, a slightly lower total lung protein when comparing influenza infected to protein in the bal from influenza naïve mice challenged with p. aeruginosa (table ) . supporting previously published studies showing a generalized pro-inflammatory cytokine environment in the aged immune system, we provide evidence for significantly (p = ae ) and an increase in ifnc (p = ae ) was detected. the decrease in gm-csf correlates well with a previous report that gm-csf is less prevalent in influenza resolved animals (table ). we also report a noticeable change in the immune cell populations with respect to b-cells, cd + t-cells, and the myeloid cell populations. there is a trend of increased prevalence in cd t-cells in the post-influenza environment across all ages. b-cell numbers also trend toward increase in influenza treated animals in young and adult animals; however, there is a noticeable decrease in the bcells in aged animals. across all age groups, there is a general decrease in frequency of cells that would normally make up the myeloid cellular fraction of the bal (macrophages, neutrophils, dendritic cells, and natural killer cells) ( table ). our study also shows, as cited by others, that toll-like receptor (tlr) gene expression in the post-influenza environment is decreased in cells found in the bal after both influenza and pseudomonas infection. our data support the previous finding of a reduced expression of tlr mrna in influenza-cleared mice when we measured tlr , , , and . only tlr showed differences with respect to age with young mice showing little or no detectable change in tlr mrna expression. our results show an increase in the expression across all tlrs examined in the aged mice group (table ) irrespective of influenza infection status. these data support earlier studies performed with adult mice that showed reduced tlr mrna expression in the post-influenza environment. this study also expands the current understanding of the potential role of age in influenza mediated bacterial infection-induced mortality. the impact of these alterations in the immune microenvironment across age groups and infection status is highlighted by the ability of bacterially challenged animals to clear infection. assessment of bacterial load in the lungs of p. aeruginosa challenged mice indicated a difference in young and adult mice if previously infected with influenza virus. in aged mice, both influenza challenged and influenza-naïve mice had higher bacterial loads and less variability when comparing within the age group, supporting the risk of age alone in susceptibility to bacterial pneumonia (table , figure ). taken together, these data support the potential role for both virus-mediated and age-mediated alteration of innate immune effectors in the pathogenesis of influenza and increased the susceptibility to secondary bacterial infection that results from influenza infection in mice. these findings highlight distinct differences in the immune environment between age groups and thus reveal necessity for further examination as to the mechanisms of immunity across age with respect to current infection status. garnering a clearer understanding as to the complex interaction of host and pathogen with respect to age in influenza infections is central to the development of increased efficacy in vaccine and therapeutic strategies. prospective estimation of the effective reproduction background pandemic influenza a (h n ) virus (ph n ) emerged in early and rapidly spread to every continent. an urgent priority for international and national public health authorities was to estimate the transmissibility of the pandemic strain for situational awareness and to permit calibration of mitigation strategies. the basic reproductive number, r , is defined as the average number of secondary cases that index case generates in a completely susceptible population, and is a common measure of transmissibility. however, it is difficult to estimate r without an understanding of the degree of any pre-existing immunity in the population. the effective reproductive number, r, is defined as the average number of secondary cases that index case generates, and can be estimated over time (i.e. r t ). wallinga and teunis described a method to estimate r t based on illness onset dates of the cases while assuming that all secondary cases would have been detected, and cauchemez et al. extended the method to permit prospective estimation by adjusting for secondary cases that have not yet experienced illness onset at the time of analysis. we describe how the method can further be extended to account for reporting delays, allowing true real-time estimation of r t during an epidemic, and we illustrate the methodology on notifications of ph n and associated hospitalizations in hong kong. we obtained data on all laboratory-confirmed ph n infections ('cases') reported between may and november , to the hospital authority and center for health protection in hong kong collated in the eflu database. a subset of the cases was hospitalised. the database also included information on age, sex, illness onset date, laboratory confirmation date, and contact history (for the early cases). laboratory-confirmed ph n infection was a notifiable condition throughout our study period. we extended existing methods for estimating r t over time to allow for reporting delays between illness onset and notification, and between illness onset, notification, and hospitalisation for those cases that were hospitalised, where the reporting delay distribution were estimated empirically from the data. we further extended the methodology to allow for imported cases (infected outside hong kong) contributing to the estimation of r t as infectors but not infectees. we used multiple imputation to allow for missing data on some symptom onset dates to make best use of all available data. we used a serial interval with mean (standard deviation) of ae ( ae ) days, and in sensitivity analyses, we used serial intervals with mean ae days and ae days. statistical analyses were performed in r version . . (r development core team, vienna, austria). in late april following the who global alert, hong kong initiated containment protocols to attempt to delay local transmission of ph n for as long as possible. these measures included screening at ports, airports, and border crossings, and enhanced surveillance for people with influenza-like illness, particularly for those who had recently returned from abroad. laboratory testing capacity was substantial due to heavy investment in local infrastructure following previous experiences with avian influenza a ⁄ h n in and severe acute respiratory syndrome in . laboratory-confirmed ph n cases were isolated until recovery, and their close contacts were placed under quarantine for days. imported cases were identified sporadically through may and early june . the first case of ph n not traceable to importation (i.e. a local case) was identified on june and triggered a change to mitigation phase measures. some containment measures, including isolation of cases, were continued until the end of june to allow a soft transition between containment and mitigation phases. as an immediate measure to try to reduce community transmission of ph n , all childcare centres, kindergartens, and primary schools were proactively closed for days (subsequently extended for another - days to summer vacation in early july). any secondary schools in which one or more confirmed ph n case was identified were reactively closed for days. on june the government opened eight designated flu clinics across the territory to provide free medical consultation for outpatients with influenza-like illness and free laboratory testing for ph n . these clinics resumed regular chronic disease services in mid-august, and laboratory testing and antiviral treatment was restricted to high risk groups in september. the various interventions are highlighted in figure (a), superimposed on the epidemic curve of laboratory-confirmed ph n cases and ph n -associated hospitalizations. around % of the cases were hospitalised, and this proportion increased somewhat towards the end of the epidemic. figure (b) shows the estimates of r t based on laboratory-confirmed ph n cases. the estimated r t peaked at ae on june , and fell below between june and july (which was within the school closure period). r t fluctuated between ae and ae through the school summer vacations in july and august, it subsequently increased to around ae - ae after schools reopened in september until the epidemic peaked in late september, and then fluctuated below as the epidemic declined. the trends in r t based on h n -associated hospitalizations were similar, although with wider confidence intervals due to the smaller number of events ( figure c ). the extension of the methods to allow for reporting delays avoided substantial bias in realtime estimates of r during the epidemic for the most recent days, and closely tracked the final estimates of r t . our results suggest that ph n may have had slightly lower transmissibility in hong kong than elsewhere. for example, estimates of r t were around ae - ae in new zealand and australia. lower transmissibility in hong kong has been associated with school closures in june and july followed by summer vacations from july through august. furthermore, in hong kong the influenza virus usually does not circulate after august, and therefore seasonality could also be a cause for the lower r t . on the other hand, the interventions applied during the mitigation phase, such as the widespread use of antiviral treatment in hong kong and the pre-existing immunity in the ageing population in hong kong, may also be associated with lower transmissibility. there are some limitations to our work. first, we only used aggregated data, and we did not consider the heterogeneity among the cases in terms of sex and age or other factors. therefore our estimates can only provide a snapshot of the overall trend, but limited information for any specific subset of population. secondly, we did not consider the possibility that cases might be infected in hong kong and exported to other countries, which could lead to slight underestimation of the transmissibility. one has to be careful in translating the estimated r t to the effectiveness of any specific interventions, as interventions may not be the only factor influencing the transmissibility; for example, a depletion of the susceptible population during an epidemic can also be a factor for the decline in r t . in conclusion, real-time monitoring of the effective reproduction number is feasible and can provide useful information to public health authorities for situational awareness and planning. in affected regions, laboratory capacity was typically focused on more severe cases, and changes in laboratory testing and notification rates meant that that case counts may not necessarily reflect the underlying epidemic. a useful alternative to case-based surveillance is surveillance of the subset of severe infections, for example hospital admissions, or icu admissions, and our results show that it was feasible to monitor ph n -associated admissions in real-time to estimate transmissibility. influenza antigenic cartography projects influenza antigens into a two or three dimensional map based on immunological datasets, such as hemagglutination inhibition and microneutralization assays. a robust antigenic cartography can facilitate influenza vaccine strain selection since the antigenic map can simplify data interpretation through intuitive antigenic map. however, antigenic cartography construction is not trivial due to the challenging features embedded in the immunological data, such as data incom-pleteness, high noises, and low reactors. to overcome these challenges, we developed a computational method, temporal matrix completion-multidimensional scaling (mc-mds), by adapting the low rank mc concept from the movie recommendation system in netflix and the mds method from geographic cartography construction. the application on h n and pandemic h n influenza a viruses demonstrates that temporal mc-mds is effective and efficient in constructing influenza antigenic cartography. the web sever is available at http://sysbio.cvm. msstate.edu/antigenmap. as a segmented, negative stranded rna virus, influenza virus is notorious for rapid mutations and reassortments. the mutations on the surface glycoproteins (ha and na) of influenza viruses are called antigenic drifts, and these antigenic drift events allow the virus to evade the accumulating immunity from previous infection or vaccination and lead to seasonal influenza epidemics. a reassortment event with a novel influenza antigen may result in antigenic shift and cause influenza pandemic. for instance, the h n pandemic virus is a reassortant with a swine origin ha antigen. vaccination is the primary option for reducing the effect of influenza, and identification of the right vaccine strains is the key to development of an effective vaccination program. the antigenicity of an optimal vaccine strain should match that of the epidemic strain. in influenza surveillance program, the influenza antigenic variants are generally identified by the immunological tests, such as hemagglutination inhibition (hi) assay, microneutralization (mn) assay, or elisa. these immunological assays measure the antigenic diversity between influenza viruses by comparing the reaction titers among the test antigens and reference antisera. however, data interpretation of the data from these assays is not trivial due to the embedded challenges such as data incompleteness, high noises, and low reactors. by mimicking geographic cartography, influenza antigenic cartography projects influenza antigens into a two or three dimensional map using immunological datasets. antigenic cartography can simplify the data interpretation, and thus, facilitate influenza antigenic variant identification. recently, we developed a novel computational method, temporal matrix completion-multidimensional scaling (mc-mds), in antigenic cartography construction. in this paper, we described the details of temporal mc-mds, especially the original concepts introduced in this method, and how they can achieve the robustness in antigenic cartography construction. our method included two integrative steps: it first reconstructs the hi matrices using low rank mc method, and then generates antigenic cartography using mds with a temporal regularization. the mc concept was adapted from the movie recommendation system in netflix and the cartography concept from geographic cartography. in , netflix, an online dvd and blu-ray disc rentalby-mail and video streaming company, held a -year netflix prize contest (http://www.netflixprize.com/) on computational methods for improving its recommendation system. in its recommendation system, netflix collected the rating data from the individuals. based on his or her renting history and the ratings in the systems (e.g., from evaluators and other renters), netflix recommendation system suggests certain movies to a renter. apparently, no individuals would be feasible to provide ratings for all of the movies, as it will take hundreds of years for a single person to rate over movies available from netflix. thus, the resulting rating data is an incomplete matrix, and it can be as sparse as less as %. the challenge in netflix recommendation system is a classic mc problem. [ ] [ ] [ ] [ ] [ ] as the inspiration of netflix prize contest, many efficient low rank mc algorithms were developed, for instance, opt-space, svt, cf, bellkor, pf, and fwls. eventually, the team bellkor's pragmatic chaos won this contest. their methods combines nonlinear probe blending and linear quiz blending to come up with a predictor bigchaos. matrix completion estimates the unobserved values based on the observed values. the users can refill the missing data without repeating the experiments. furthermore, mc will help reduce the noises in the data, for instance, those biases by different individuals performing experiments. in influenza antigenic characterization, hi assay is a commonly used assay for antigenic analysis, since hi assay is relatively economic and easy to perform. however, hi is labor intensive, and it is almost impossible for any individual lab to complete the hi assays for all pairs of antigens and antisera during influenza surveillance. in addition, both testing antigens and the reference antisera are dynamic. for instance, in seasonal influenza surveillance, generally only contemporary antisera are used in experiments. thus, we will have to integrate multiple hi tables in order to evaluate the overall antigenic changes for influenza vaccine strain selection. the resulting hi tables will be incomplete, and the observed entries in the integrated hi data can be as less as %. the completion of this matrix can be formulated as a typical mc. briefly, given the combination of hi matrix with m antigens and n antisera, the hi matrix can be represented as m m·n = (m ij ) m·n , where m ij denotes the hi values from the reaction between testing antigen i and antiserum j. the low rank mc assumes that both antigen and antiserum can be embedded into a low rank space. to be specific, the low rank mc method is to seek matrix u m·r , v n·r and a diagonal matrix r r·r , where m = u m·r r r·r (v n·r ) t . in order to achieve this goal, the optimization formulation has been employed, which can be represent as following, where e denotes the observed entries in hi matrix and g(x) is a regularization function. the eqn ( ) is the standard format of a low rank mc formulation. the geographic cartography is a common technique to display the cities and their geographic distances in a map. this cartography can be generated using mds based on a geographic distance matrix. figure (a) shows the antigenic cartography generated using a distance matrix with seven cities, and figure (b) is a map for comparison. as an analog of geographic cartography, the influenza antigenic cartography maps the influenza antigens into a two or three dimensional map based on the distance matrix generated using immunological data. this incomplete matrix can be filled through mc algorithm discussed in section mc and netflix. low reactors, non-random date incompleteness, and temporal model generally, three types of data are present in a combined hi matrix: high reactor, low reactor, and missing values. among these three data types, high reactors are the most reliable data points. the low reactors are those values present in the hi matrix as ''equal to or less than a threshold h'', where h can be , , , or . low reactors have similar values in the affinity dataset but could be from different binding settings. these low reactors are present due to the detection limits of biotechnology, and they are not reliable. both these missing values and low reactors make it very difficult to analyze and interpret antigenic correlations amongst tested antigens and reference antigens. to our best knowledge, none of the existing mc method can handle the threshold values. in addition, the non-random incompleteness of influenza immunological datasets generates an additional challenge in traditional mc methods, which are based on the assumption that the observed values are randomly distributed among the matrix. in a typical combined antigenic hi data, most of the off-diagonal entries are missing values or low reactor values. in order to overcome the above issues, we incorporated a regularization function into the eqn ( ), where this indicator function is only valid for those entries with low reactor values. an alternating gradient decent method is applied to solve the optimization problem in eqn ( ) . in addition, a temporal mds method is proposed to project the antigens into a or dimensional map. x where d ij is the average distance between virus i and virus j, t i is the isolation year of virus i, d ij is the distance between virus i and virus j in cartography, d ac i is the distance between virus a and center of group i, and d c i c j is the distance between the centers of group i and group j. all the parameters are tuned by cross validation. we named this method as temporal mc-mds. by applying temporal mc-mds method in an h n dataset, low reactors. figure (a) is a three-dimensional influenza antigenic map based on this data by using mc-mds method. the reported clusters (hk , en , vi , tx , bk , si , be , be , wu , sy , and fu ) were displayed in the core of a spiral s-shape, and bk and be are located at the turning point of this s-shape. however, the antigenic distances between some viruses are incorrect. for example, the distance between hk and fu in the projection is ae units, which is close to the distance between hk and bk ( ae units). the main reason leading to those inaccurate distances is the unique distribution of hi datasets described in section . . in comparison, with the temporal model, not only the viruses in clusters have been clearly separated, but also the antigenic distances between each cluster are proportional to their isolation time interval. in this updated cartography ( figure b ), the antigenic distance between hk and fu is ae units, where the distance between hk and fu is ae units. this result suggested that the temporal information is critical for antigenic cartography construction for immunological datasets spanning a long time period. the hi data from seasonal influenza surveillance belong to this category. for seasonal influenza virus ⁄ pandemic influenza viruses within a short time span, the temporal model is probably not necessary, as there is lack of long-term immunological pressure present in the population. figure (c) is an antigenic cartography generated using a hi dataset with h n influenza viruses spanning from april of to june of . this map demonstrates that there is lack of antigenic drifts during the first wave of this pandemic influenza as all of these viruses are mixed altogether. our limited studies on h and h avian influenza viruses suggested the temporal model is not needed for avian influenza viruses. however, extensive studies are required to investigate whether there is any special data structure present in this type of data. in this study, we described in details the concepts and applications of new computational method, temporal mc-mds for influenza antigenic cartography construction. we formulate the influenza cartography as two integrative steps: low rank mc problem from the concept of netflix movie recommendation system and mds from geographic cartography construction. in order to handle two additional challenges, including low reactor and non random distribution of antigenic data, a temporal model is incorporated into mc-mds as temporal mc-mds. our applications demonstrated that temporal mc-mds is effective in constructing influenza antigenic cartography. the three dimensional antigenic cartography for a ⁄ h n seasonal influenza virus without temporal model, and the antigenic clusters were defined in ref. [ ] ; (b) the three dimensional antigenic cartography for a ⁄ h n seasonal influenza virus with temporal model; (c) the two dimensional antigenic cartography for a ⁄ h n pandemic influenza without temporal model, and these viruses were labeled in shape by the corresponding month for them to be detected. one grid is corresponding to a twofold change in hemagglutination inhibition experiment. the mechanisms driving the three waves of infection and mortality in the uk in - are uncertain. although the circulation of three distinct viruses could have generated three waves of infection, the virological evidence required to prove or disprove this hypothesis is lacking. social distancing, an alternate mechanism for generating fluctuations in the effective susceptible pool and therefore explaining multiple waves of infection, , was not generally imposed in the uk as it was in the us and australia. we are therefore motivated to explore the possible role of continual population-level changes in the average protective response against the circulating virus in generating a multi-wave pandemic, within a biologically motivated deterministic model for influenza transmission. the nature and duration of protection against further infection following recovery from influenza is uncertain and depends on the mode and tempo of viral evolution, as well as the response of the cellular and humoral arms of the adaptive immune system. for a given seasonal ⁄ pandemic strain, memory b-cells may generate a specific antibody response in a portion of the adult ⁄ elderly population, depending on the exposure to related antigenic sub-types. however neutralising antibodies are unlikely to be a widespread immunological response to a novel (pandemic) strain. memory t-cells which recognise conserved internal viral proteins may be a more common mechanism for protection; the generation of very high levels of cytotoxic cd + t-cells potentially facilitates rapid viral clearance, , and lower levels of cd + t-cells perhaps provide partial protection. in this work we explore key drivers of multi-wave pandemics within phenomenological models that incorporate different immune response mechanisms building on existing models , incorporating the role of evolving population-level protection in multi-wave pandemics. we use weekly reports of influenza mortality rates for five administrative units in the uk (blackburn, leicester, newcastle, manchester and wigan) where records from block censuses instigated by local medical officers to record the cumulative incidence of reported symptoms in each wave in a sample of or more households are also available. the symptom reporting data allows us to estimate the case fatality rate and thus use the mortality time series to constrain our transmission model. furthermore, the incidence of individuals reporting symptoms in multiple waves provides information about the acquisition and loss of immunity. we extract the death rate and symptomatic (re)infection rates predicted by our model prevalence for a given set of parameters and estimate a likelihood-based on a comparison to all the death and cumulative reported incidence data assuming a negative binomial error distribution. we utilise monte carlo markov chain (mcmc) methods with parallel tempering algorithms to maximise this likelihood and obtain parameter estimates. parallel tempering -which concurrently searches for maximal likelihood parameter solutions on a set of scaled likelihood surfaces -allows for relatively rapid exploration of the parameter space. we use bayesian information criteria (combined with qualitative assessment of biological plausibility) to aid model selection. we have implemented a deterministic compartmental transmission model, which allows for a variety of phenomenological modes of protection against the pandemic virus. to facilitate this, we stratify the population into two groups; the 'experienced' population (stratum ) who have had been exposed to an influenza virus and the 'naive' population (stratum ) who have not. in each stratum, i hosts may be classified as either susceptible s i , exposed e i and e i , having (recovered from) a symptomatic i i (r i ), or asymptomatic a i (ra i ) infection. note that the states tq i , tq i , e i , t i , and t i are included so that the hosts move between the key epidemiological states with a peaked (rather than exponential) distribution of waiting times. hosts in the experienced stratum may exhibit reduced susceptibility, infectiousness, and symptomatic proportion compared to naive hosts, parameterised by e i , e s , and e a , respectively; however note that depending on the model parameters, there may be fully susceptible hosts within the experienced stratum. in addition, we assume homogeneous population mixing and a constant basic reproduction number r with the force of infection: modulated by a sinusoidal seasonal term with amplitude b with phase chosen to maximise transmission in the winter season. here n is the total population size, and x e is the initial fraction in the experienced strata. the proportion of symptomatic cases a and the case fatality rate l are permitted to vary from wave to wave (and given indices , or accordingly). the transmission dynamics is described by the following set of coupled ordinary differential equations. where s in, = p utq i and s in, = in order to divert recovered infectious hosts from the naive stratum into the experienced stratum. the probabilities of gaining permanent protection are q = q and q = . the latent exposed period is fixed to be c = ⁄ ae days, and the rate of recovery is parameterised by m = ⁄ t inf , where t inf is the infectious period. hosts with prior sterilising protection begin in q and move into s at rate u q = ⁄ t wq . recovered hosts (r i ) migrate back to s at a rate u = ⁄ t w . the state p contains hosts with permanent protection. the modes of protection captured in this model are: i. permanent prior protection (beginning in state p ), ii. waning prior protection (beginning in state q ), iii. permanent acquired protection with probability q (moving into state p ), iv. waning acquired protection with probability ) q, and, v. partial prior protection (beginning in state s ) resulting in reduced infectiousness (e i ), susceptibility (e s ), and symptomatic proportion (e a ). in the context of this model, 'permanent' protection refers to protection which lasts for the duration of the epidemic. here we explore the results of parameter fitting to two models which differ in the nature of the assumed pre-existing protection in the community at the beginning of the pandemic. protection hypothesis assumes that the prior protection is sterilising but temporary, whilst protection hypothesis assumes that the prior protection is partial but permanent and may act on susceptibility, infectiousness, and ⁄ or asymptomatic proportion. each model allows waning acquired protection and for a proportion q of the experienced population to gain permanent protection following infection. fitted parameters common to each model are t inf , b , q, t w , a, l and the proportion beginning in p x i . prior protection hypothesis : sterilising, waning prior protection we fix x e = and fit for q (t = ) ⁄ n and t wq so that protective modes i, ii, iii, and iv are enabled ( figure ). it is important to note that due to the slow convergence of the mcmc chains, we cannot guarantee that our parameter estimates correspond to the global minimum. furthermore, parameter estimates can only be meaningfully interpreted for good fits to the data. due to the prediction of a fourth (unobserved) wave for the model fit to blackburn, we do not report these parameter estimates here. the fits to the leicester data are generated with the parameter set r = ae , a = ae , a = ae , a = ae , t w = ae years, t wq = ae years, we fix q (t = ) ⁄ n = and fit for x e , e a , e i , and e s so that protective modes i, iii, iv, and v are enabled (figure ) . the parameters corresponding to the fit in figure for leicester are r = ae , a = ae , a = ae , a = ae , t w = ae years, p (t = ) ⁄ n = ae , s (t = ) ⁄ n = ae , b = ae , t inf = ae days, q = ae , e a = ae , e i = ae , and e s = ae . our model with protection hypothesis -which, similarly to the model discussed in ref. [ ] , assumes that a sub-population has waning sterilising prior protection -is able to generate multiple waves of infection via the continual replenishment of s from an initially large proportion (over %) of hosts with prior protection in q combined with the waning of acquired immunity in around % of cases on a time-scale of months. disease severity as measured by symptomatic proportion increases from % in the first wave to above % for the second and third waves. over a quarter of the population are initially permanently immune, and a large r value of ae drives transmission in the remaining population. protection hypothesis -which assumes that prior protection offers partial susceptibility and ⁄ or reduced infectiousness or symptomatic disease -performs slightly more poorly; the fit to the leicester data has an inferior likelihood (although the mortality data only likelihood is a little larger), despite the higher dimensionality of the model. nevertheless, the model fit still mirrors many characteristics of the data, particularly for leicester. we note that for this model, a is very near the lower limit, corresponding to ubiquitous exposure in the first wave. in this scenario, refuelling of the susceptible pool to generate secondary and tertiary waves is still possible due to a shorter waning time of acquired protection (well within months) and a lower probability of gaining permanent protection following infection, when compared with the parameter estimate for hypothesis . the parameter estimates suggest that approximately % of the population initially experiences reduced disease severity (e a $ ae ), but similar susceptibility and infectiousness. a larger value for r $ ae is required to drive transmission despite low numbers beginning in p , due to the large number of hosts who acquire temporary or permanent immunity early on in the pandemic. it is clear that, at least mathematically and perhaps biologically, there are multiple possibilities for the structure of population-level protection which are compatible with the generation of multiple pandemic waves. however, whilst the models considered here are able to explain the observed mortality and reinfection data for some patterns of infection and mortality (e.g. leicester), they are not consistently able to reproduce a pandemic which dies out after three waves across the connected populations we are studying (e.g. for blackburn). it is challenging to construct a deterministic model for the spread of disease within multiple locations in the uk in , which assumes homogeneous mixing without modulation of the transmission rate by social distancing. an improved model working with these assumptions likely requires a richer structure for the host protection response than the structures we have explored thus far. we are currently seeking improved fits to the data by implementing a number of biologically defensible exten-sions to our model, including incremental immunity whereby t w increases by a factor v after each exposure to the pandemic flu, and incremental loss of prior protection whereby a increases as hosts lose their sterilising prior protection. it is important to note that the mechanism(s) generating differences in the pandemic experience recorded in geographically connected locations is an open question; true differences in demography, varying degrees of reactive social distancing, inhomogeneities in the circulation (or circulation history, i.e. prior immunity) of viral strains, stochastic variations, and ⁄ or unique socio-cultural ⁄ behavioural conditions may all contribute to this effect. the h n experience in australia and elsewhere highlighted the difficulties faced by public health authorities in diagnosing infections and delivering antiviral agents (e.g. oseltamivir) as treatment for cases and prophylaxis for contacts in a timely manner. consequently, forecasts from mathematical models of the possible benefits of widespread antiviral interventions were largely unmet. we summarise results from a recently developed model that includes realworld constraints, such as finite diagnostic and antiviral distribution capacities. we find that use of antiviral agents might be capable of containing or substantially mitigating an epidemic in only a small proportion of epidemic scenarios given australia's existing public health capacities. we then introduce a statistical model that, based on just three characteristics of a hypothetical outbreak [(i) the basic reproduction number, (ii) the reduction in infectiousness of cases governments and public health agencies worldwide, spurred by outbreaks of sars and h n , have developed preparedness strategies to mitigate the impact of emerging infectious diseases, including pandemic influenza. pandemic response plans are presently being revised in light of the h n experience. [ ] [ ] [ ] many developed countries amassed large stockpiles of neuraminidase inhibitors (nais) with the expectation that they could be used to not only treat the most severely ill, but curb transmission in the community. without relevant field experience indicating how nais should be distributed, mathematical and computational modelling has been used to inform optimal deployment policy in a pandemic scenario. - models of population transmission were used to infer likely effects on epidemic dynamics, using data from human and animal studies of experimental infection and nai efficacy trials. in the australian (and wider) context, models indicated the potential for substantial benefit at the population level if nais were distributed in a liberal manner, targeting close contacts of indentified cases. furthermore, results indicated that use of limited nai resources in this way may improve the impact of case treatment due to the effects on epidemic dynamics. however, these models did not take into account logistic and other real-world constraints, such as finite diagnostic and antiviral distribution capacities, which were identified as limiting factors during the australian h n pandemic response. [ ] [ ] [ ] in particular, if using positive pcr diagnosis as a 'decision to treat' test, delays to confirmation of diagnosis, particularly once total laboratory capacity was exceeded, prevented timely delivery of nais to both cases and contacts of cases. in previous work, we have extended our existing models to examine how diagnostic strategies [e.g. using pcr confirmation versus syndromic influenza-like illness (ili) presentation as a decision to treat], diagnostic-capacity, and nai distribution capacity each impact on the ability to deliver an effective intervention. the model uses case severity (the proportion of infections deemed severe) to determine the overall presentation proportion, and so the ability to identify individuals eligible for nai treatment and contact prophylaxis. figure (a) shows a key result from the model. for each curve shown, we simulated thousands of epidemics, sam-pling across plausible ranges of parameters describing virus, population, and intervention characteristics using a latin hypercube sampling (lhs) approach. without intervention, the proportion of the population infected either symptomatically or subclinically by the end of the epidemic is around %. if a syndromic strategy (ili presentation) is used to determine provision of nais as treatment and prophylaxis, excessive distribution of drug to individuals who are not infected with influenza occurs early in the epidemic. early stockpile expiry accounts for a marginal impact of the antiviral intervention on the final outbreak size, in the order of a few percent. the second strategy modelled (pcr ⁄ syndromic) is one where pcr confirmation of diagnosis is required early in the epidemic to make treatment decisions until such time as laboratory capacity is exceeded. from this point, individuals are treated on the basis of symptoms alone -during an epidemic phase in which a substantial proportion of ili presentations will be attributable to influenza. under this strategy, the intervention is able to control the outbreak in approximately % of the simulated epidemics given the 'base case' constraints on diagnosis and delivery assumed in the model. the results highlight that a successful antiviral intervention requires a highly sensitive diagnostic strategy in the initial stages of the epidemic and comprehensive distribution of post-exposure prophylaxis. a pcr ⁄ syndromic strategy for decision to treat and provide contacts with prophylaxis is thus optimal. the surface in figure (b) shows the percentage of simulation runs for the pcr ⁄ syndromic strategy that have a final population attack rate of < % (a substantial reduction from the no intervention case of approximately %) as a function of pcr capacity and nai daily distribution capacity. as indicated by the arrow, the estimated australian pcr laboratory capacity appears to be sufficient, while significant benefits for the public health outcome may be achieved if logistical delivery constraints for nai distribution can be ameliorated. however, the probability that such an interventioneven with substantial increases in pcr and nai distribution capacity -would successfully mitigate an epidemic is low ( - %), and consequently it is difficult to universally recommend an antiviral intervention. in this study, we introduce a statistical model that predicts whether or not an nai distribution strategy based on a pcr ⁄ syndromic antiviral distribution policy will be successful in mitigating an epidemic. we thereby provide proof-of-principle for the design of a decision support tool that may be used by public health policy makers during an epidemic when faced with formulation of context specific nai distribution policy. synthetic data of hypothetical outbreaks and interventions were generated using the lhs simulations developed in ref. [ ] . we selected a random sample of outbreaks from a total of simulated epidemics ( % of model simulations). using these data, we identified independent model parameters that were most highly rank-correlated with the final attack rate. these parameters were included in a logistic regression model to assess their ability to predict whether an influenza epidemic would be successfully mitigated by an antiviral intervention (ar < %). model predictions were then validated against the full simulated dataset. full details of the simulation model, its structure, parameterisation and parameter distributions are available in ref. [ ] . use of the lhs simulation approach, and the method of model analysis and evaluation was similar to that previously described. matlab a (mathworks, natick, ma, usa) was used for the analysis and statistical model fitting. table shows results from our logistic regression model. key parameters sufficient to predict whether or not an outbreak may be controlled by the deployment of av agents are: . r , the basic reproductive number of the outbreak (assigned values between ae and ae for this example). as the value of r increases, the epidemic progresses more rapidly and is more difficult to control, explaining the negative correlation coefficient. . e t , the relative infectiousness of treated individuals (assigned values between ae and ae ). higher values for this parameter indicate only modest drug effects on transmission, explaining the negative correlation coefficient. . g, the proportion of infections that are severe (assigned values between ae and ae ), and which in turn determines the presenting proportion (derived values between ae and ae ). as the presenting proportion increases, the ability to identify and treat cases and deliver prophylaxis to contacts also rises, increasing the impact of the antiviral intervention. the roc curve ( -specificity versus sensitivity, not shown) for the logistic regression model specified in table has an area under the curve of ae , demonstrating that the model predicts the success of an antiviral intervention extremely well. for example, with a sensitivity of % we still have a specificity of approximately %. evaluation of the pandemic response has emphasised the need for early informed decision-making to implement proportionate disease control measures. our model identifies a low probability of successful epidemic mitigation using targeted antivirals alone (figure and ref. ), in distinction to results from models that fail to account for the diagnosis and delivery constraints inherent in any public health response. the decision support tool (table ) highlights key epidemic characteristics that are predictive of a high likelihood of effective mitigation. the reproduction number was one of the earliest parameters estimated from early outbreak data during the h n outbreak. , our findings reinforce the importance of characterising epidemic severity as early and as accurately as possible, in order to inform a proportionate pandemic response. critically, a typically mild pandemic (low g), such as that experienced in , is predictably difficult to contain using a targeted antiviral strategy due to the low proportion of infectious cases that present to health authorities. the relative infectiousness of treated individuals, e t , is strongly negatively correlated with successful mitigation, perhaps a surprising result given the model's underlying assumption (based on available epidemiological and human clinical trials data) that e t lies in the range [ ae , ]. that is, nais provided as treatment have a maximum impact of just a % reduction in infectiousness. however, our previous results show a strong synergistic effect of treatment when overlayed on a contact prophylaxis strategy, explaining the observation here that e t is critical in determining likely success of an intervention. despite the limited impact of treatment at the individual-level, the model outcomes are highly sensitive to the value of the relative infectiousness of treated cases. it follows that determination of e t is important for predicting the population-level outcome of a control effort. a 'small' reduction (of the order approximately %) may be extremely valuable in terms of success of a public health control strategy, and so should not be discounted. using a mathematical model which takes into account some of the key logistic constraints that are inherent to healthcare responses, we have derived a logistic regression model for estimating the probability that an antiviral intervention based on liberal distribution of nais as treatment and prophylaxis could successfully mitigate an influenza epidemic. the model demonstrates an excellent degree of accuracy when applied to synthetic data. the choice of parameters for the regression model was restricted to those that were both highly correlated with the success of the intervention and hopefully feasible to measure during the early stages of an emerging epidemic. the model could therefore be a useful near real-time decision support tool for public health policy in the face of an influenza epidemic, although further validation on a range of synthetic data (and real-world data where available) is required. influenza to seasonal flu status to avoid overstretching the demands on healthcare services. a great deal of information has emerged as the result of the pandemic response exercises conducted by affected countries. however, uncertainties remain regarding the effectiveness of intervention measures, as well as the feasibility and the timing of their implementation. mathematical and computational models [ ] [ ] [ ] have been used to project the outcomes of influenza outbreaks under various scenarios and epidemiological hypotheses. motivated by the events of and public health measures adopted by the taiwan cdc, we use a stochastic, individual-based simulation model to study the spatio-temporal transmission characteristics of the h n virus, so as to quantitatively assess the effects of early intervention strategies. our stochastic disease simulation model builds upon a highly connected network of individuals interacting with each other via social contact groups. to represent the daily interactions of approximately million people living in taiwan, we constructed a computer-generated mock population based on national demographic and employment statistics (to derive daily commute patterns) from the taiwan census (http://www.stat.gov.tw/). each individual is created with a set of attributes, including age, sex, residence, family structure, and social standing (employment status, etc.). based on their attributes and the time of day, each individual is assigned to miscellaneous contact groups, where the potential of interactions between any two individuals resulting in flu virus transmission occurs. such epidemiological properties are defined by empirically parameterized attributes such as basic reproduction number r , transmission probability, contact probability and associated probability distributions outlining the disease's natural history. additionally, intervention measures are implemented as scheduled events that could alter control parameters during the course of a simulation run. the targeted basic reproduction number (r ) in all our simulations is ae , following the suggested range by who of ae - ae . as the latent ⁄ incubation and infectious periods for h n have not yet been reliably ascertained, we adopt the natural history of the and pandemic influenza viruses. , here, the latent period ranged from to days, with a median value of ae days. the infectious periods begin day prior to symptom onset and can continue for - days, with a median value of ae days. twothirds of the infected individuals will develop clinical symptoms, and the asymptomatic cases will have half the infectious strength. the efficacy of antiviral drugs (oseltamivir) and vaccines are based on these studies. , for the source region of the infected cases, we use the north american continent (canada, mexico and united states) with an estimated total population of and an average hours of flight time to taiwan. the average daily passenger number is based on the annual statistical report on tourism, tourism bureau, taiwan (http://admin.taiwan.net.tw/english/statistics/year.asp? relno= ). each simulation lasts days and starts with a baseline simulation of r % ae h n pdm outbreak at the source region. the outbreak was adjusted to approximate clinical attack rate (car) in the united states, april -march , . we estimate the daily number of imported cases according to average daily passenger numbers and their probability of holding a disease status. we then apply airport exit ⁄ entry screening per corresponding success rates, by subtracting the number of identified symptomatic cases. we also consider latently infected passengers with inflight disease progression, by fitting a gamma distribution to the cumulative distribution of time to onset data with hours average flight-time, as presented by pitman et al. the daily imported cases are seeded according to the traveling patterns of foreign tourists and residents returning home. from the disease's natural history, we derive that roughly % of the infected travelers present no symptoms; the percentage increases if most symptomatic individuals elect not to travel in their condition, or are stopped by airport screening. we use the official epidemic data provided by the taiwan cdc to calibrate the simulation model and perform regression analysis on scenario parameters. this data is a close estimation of the weekly new clinical cases of h n pdm patients. it consists of weekly opd (outpatient department) icd- code (influenza) tallies collected by the bureau of national health insurance, taiwanadjusted to exclude seasonal flu patients and to account for uninsured patients. we formulate our scenario settings according to events in taiwan, and establish settings to approximate the actual events. with domestic events and intervention schedules fixed in time, the start date determines the simulation outcomes and the data range for selected indicators, such as the mean car, the epidemic peak, and several significant dates for the incoming index case events. we plot the taiwan weekly h n opd cases alongside the weekly new clinical cases from our simulation results in figure . our simulations not only capture the epidemic trend, but also pick out the most likely date, may , for identifying the first symptomatic case at airport screening based on practical assumptions. we further analyze the effectiveness of various mitigation measures with february , as the empirical start date for h n pdm in north america. the simulation result confirms that by the time we identified the first symptomatic case at the border screening, infected cases had already made their way to the public. by our calculation, roughly four such cases had passed in each of our scenario settings, with the first case happening as early as weeks before detection. figure also highlights the importance of the timing for the implementation of mitigation measures; for example, a -day-delay of the identical intervention plan results in nearly an additional % of the population being infected. therefore, the rule of thumb for healthcare officials is to implement intervention measures as early as possible. in our study, we have ignored the possibility of inflight transmission and any false positive results by airport screening procedures. to assess the effectiveness of each mitigation strategy of interest and their combinations, we take the calibrated simulation model and perform simulation realizations for groups of scenarios containing only those intended mitigation measures, and analyze the averaged results. for example, in the airport exit screening policy only scenario, the first imported symptomatic case can be delayed up to months, and the epidemic peak can be delayed up to days. as the data suggests, the exit screening policy alone has very little impact on car. combining various screening success rates for both exit and entry screening allows us to quantitatively assess their beneficial ramifications on the epidemic. for example, there is very little additional benefit between % and % suc-cess rates for entry screening policies when exit screening policies are adequate, as the enhanced border screening only delayed the epidemic peak by day, and reduced car by < ae %. base on this result, the government should not attempt to exhaust all its resources in securing the border during a pandemic event, because the return of such a policy will be disappointing. instead, a response plan with a shifting focus on health resource allocation and the capacity of adjusting intervention strategies in line with the developing epidemic will be most effective. based on the same principle, we perform experiments with assorted scenarios, including relaxing entry screening policies after identifying the first imported symptomatic case, mass vaccination based on the actual vaccination schedule of h n pdm in taiwan, and altering the start dates of the vaccination schedule. our results show that with a reasonable reduction in the airport entry screening success rate, we conserve valuable healthcare resources, but loose a few days for the strategic planning and preparation of subsequent response measures. in other simulation scenarios, a national vaccination campaign has very little impact on the outcome, due to the late start of the vaccination schedule. we then explore the effect of a national vaccination campaign with various starting dates. the simulation results are illustrated in figure , where the benefit of an early start date for mass vaccination is clearly demonstrated. considering a scenario with an % airport exit screening success rate, % airport entry screening success rate and % symptomatic case tracing success rate, the combined intervention strategy results in: a % reduction in car if the vaccination campaign starts in mid-november; % reduction if the campaign starts in mid-october; % reduction if the campaign starts in mid-september; and % reduction if the campaign starts in mid-august. in retrospect, the taiwanese government's response to h n pdm proved to be effective. first and foremost, it initiated enhanced border monitoring and on-board quarantine inspection as soon as the threat of a flu pandemic became clear. at the same time, the domestic preparations towards h n pdm were escalated, such as antiviral drug stockpiling and distribution, and vaccine acquisition. as the h n cases increased worldwide, various revised plans were adopted and implemented; such as the shift from labor-extensive on-board quarantine inspection to the notifiable infectious disease reporting system and realtime outbreak and disease surveillance system in order to effectively track down symptomatic and exposed passengers, apply prophylaxis treatment and mandatory in-home quarantine. as a result, all h n pdm related statistics are well below the international average. in modern society, countries rely heavily on the global economy for their own prosperity. shutting down the border for any length of time is not only costly, but could have disastrous economic effects that linger long after the event is over. moreover, with nearly % of the infected passengers presenting no symptoms whatsoever, they are not detectable by any port authority's screening procedures, and the importation of the novel flu virus is therefore inevitable. many studies conclude that entry screening is unlikely to be effective in preventing or delaying the importation of influenza, and has negligible impact on the course of subsequent epidemic. however, these studies are based on the assumption that effective exit screening is in place. our study shows that as the exit screening success rate decreases, the sensitivity of the entry screening policy becomes more pronounced. with the same methodology, we can also study the effects of varying the length of flight time, or the disease's incubation time. lastly, the benefit of entry screening is even more crucial for a small island country such as taiwan, since all incoming traffic must go through the port authority where entry screening can be enforced. in england and wales, three waves of the pandemic struck in summer, autumn, and winter seasons of - . although the proportion of people reporting symptoms was often greater in the first wave, - a puzzling feature was the much higher mortality in the second wave, in which . % of the population died, compared with . % in the out-of-season first wave and . % in the third wave. an obvious hypothesis to explain the changes in mortality from wave to wave would be that the virus mutated to higher virulence after the (lower mortality) first wave. although pandemic virus reconstituted from the high mortality waves has proven to have high virulence in animals, it has not been possible to recover virus from the first wave in for comparative purposes. indeed it is questionable whether virulence mutation(s) occurring between wave and wave could have spread to so many different populations in the time-frames observed. furthermore, in all three pandemic waves, there was the same agedistribution of mortality, with more deaths occurring amongst younger adults than older adults. [ ] [ ] [ ] this 'pandemic signature', arguably due to immune protection of older adults who were exposed to a similar virus in the years before , , suggests that the - viruses were at least immunologically similar in all three waves. a second hypothesis would be that the higher case fatality in the later waves was due to higher rates of complicating bacterial pneumonia, to increased transmission of influenza virus in the cooler months of the year, or to other seasonal effects. we have considered a third (immunological) hypothesis to explain the greatly increased mortality in waves and . the underlying idea is that the mortality rate in the first wave was lower than in later waves because most persons were protected by prior immunity in the first wave, and that the mortality was higher in later waves because of waning of that short-lived immunity. this hypothesis builds on our earlier modelling papers suggesting that even before the first wave in , military, school, and urban populations in england and wales apparently had (short-lived) immune protection, presumably induced by recent prior exposure to seasonal influenza. [ ] [ ] [ ] we suggest that this short-lived strain-transcending protection was in addition to the longer-lasting immunity, presumably induced by exposures to a similar virus circulating prior to , that arguably reduced pandemic mortality for older adults in - . , cumulative mortality rates attributed to pandemic influenza were available for each of the three waves in - for populations in england and wales. we have built immunological models to potentially explain the variation in mortality rates across waves and populations. to show proof of principle, we have fitted these models to mortality data from a randomly selected sub-set of twenty populations. our key assumption was that the risk of a fatal infection would be limited to persons with inadequate immunity who were being exposed to the pandemic virus for the first time. persons who were exposed and who survived an earlier wave were assumed to be protected against death in a later wave. model a and assumptions (see figure ) before the first wave, we assumed that people could be fully susceptible (s ), or partially protected (q ), or fully protected (p) by prior immunity which was not necessarily specific for the new virus. we assumed that exposure to the new pandemic virus would be fatal (m) in a proportion h of fully susceptible persons who were actually exposed (e) in the relevant wave. for those surviving that first exposure, it was assumed that they would be permanently protected against death in later waves by an immune assumed that viral exposure and multiplication would induce an immune response specific for the pandemic virus that would protect them against death in that wave and in subsequent waves. in contrast, for persons with strong prior immune protection, p, the virus would not be able to multiply to induce pandemic-specific immune protection. between waves, it is assumed that due to the waning of non-specific prior immunity, persons in the p state can move to the q state, and persons in the q state can move to an s state before the next wave. the proportion (e) of susceptible persons exposed to productive infection in each population was estimated by applying the following version of the final size equation to the proportion susceptible (s & q) in each wave, for each population: note: in both figures and , we have omitted the flows out of the q and e states that removed persons from the risk of death. parameters: s = proportion fully susceptible to infection and death before wave ; q = proportion susceptible to immunising infection, but not to death from exposure in wave ; p = proportion temporarily protected against both immunising infection and death from exposure in wave ; n = proportion even more protected against both immunising infection and death from exposure in wave (model b only); r = basic reproduction number (the average number of secondary cases for each primary case) in a fully susceptible population; f = proportion moving from q to s between waves; g = proportion moving from p to q between waves; d = proportion moving from n to p between waves (model b); h = proportion of e that actually move to m and die. model a could provide a very good fit for the summer, autumn, and winter waves of the - pandemic (results not shown). however, because of the replenishment of the pool of susceptible persons over time, model a also predicted a fourth wave of influenza in the spring season of . as no such wave was seen, and as we could not find parameters values for model a that did not predict a fourth wave, we must regard model a as inadequate. model b was similar to model a, but with an additional stage of prior immunity (n), which could wane to p. model b allowed us to not only fit the three observed waves, but also to fit the imputed data (zero cases) corresponding to the absent fourth wave. following earlier work, , we used a bayesian approach with markov chain monte carlo (mcmc) procedures to estimate model parameters, and we used hyper-parameters to allow for parameter variation between populations. the initial conditions were specified by the parameters: p , q , s and n . from these and the other parameters, it was possible to simulate the behaviour of model a over three waves, and of model b over four waves, and to estimate the expected numbers dying in each wave in each population. we calculated the log likelihood of the observed numbers of deaths given the parameter estimates, and we used mcmc simulation to generate the posterior distributions of parameters. although we obtained an excellent fit between observed and expected numbers of deaths in each of the three waves for the populations for model a, we could not find parameter values for model a that would fit the three observed waves without giving rise to a fourth wave in the spring of . accordingly, in the modified model b, we allowed for an additional stage of prior immunity (figure ) , and we fitted the model to the same data, plus imputed data corresponding to 'the absent fourth wave'. we obtained a very good fit to the three observed waves and the absent fourth wave in each population. the % credibility intervals for parameter estimates, derived from the posterior distributions of the hyper-parameters were: h = . - . , s = . - . , q = . - . ; n = . (fixed); p = ) s ) q ) n ; f = . - . ; g = . - . ; d = . - . and r = . - . . this analysis had allowed all parameters to vary from population to population under the constraints of the hyper-parameters. however, several of the biologically determined parameters might be expected to be more constant from population to population, whereas those dependent on mixing history and other social characteristics which vary more widely from population to population. to test this possibility, we fixed the mean values for the more biological parameters (f = . ; d = . ; g = . ) and estimated the % credibility intervals for the others as: h = . - . ; s = . - . , q = . - . ; and as before n = . (fixed); in a subsequent paper we will be able to provide more details of the method, the robustness of the assumptions, and the results from fitting to many more populations. this short report suggests that the observed patterns of mortality in england and wales over the three waves of the - influenza pandemic , can be explained by an immunological model. in particular, the lower mortality in wave one can be explained by the assumption of protective immunity antedating the first wave, arguably induced by prior exposure to seasonal influenza. , the much greater mortality in wave two can be explained by the waning, between wave one and wave two, of that short-lived and less-specific immune protection. the somewhat lesser mortality in wave three and the 'absent fourth wave' can be explained in terms of the progressive acquisition of immunity specific to the pandemic virus. the credibility estimates for parameters are of potential interest. for example, r estimates of . - . across different populations are consistent with our earlier findings. , if all persons had been susceptible, such r values imply that the virus would have infected most people in all populations. however, even in the first wave, the proportion susceptible, s + q , was < % in all populations, so that a considerable number of persons escaped productive infection in that wave; as their immunity waned, they became susceptible to infection in the later waves. it is likely that the variation in r between populations is due to different rates of population mixing. estimates for h indicate that between % and % of infections in the most susceptible persons were fatal; the higher values of h could reflect higher rates of secondary bacterial infection in the most socially disadvantaged and overcrowded populations. although we have shown the plausibility of an immunological explanation for wave to wave changes in pandemic mortality, we cannot assume that our particular model is even approximately correct. nor can we exclude the possibility that the higher mortality in the later pandemic waves in - was because of genetic change in the virus in later waves, or because of changing rates of secondary bacterial infection or seasonal effects. nevertheless, there is growing evidence that the population spread of pandemic influenza, whether in - , or in , , can be constrained by significant prior immunity, even for viruses that are ostensibly novel. previous reports, reviewed in ref. [ , ] , support the idea of strain-transcending immune protection, which can wane over periods of a few months. this form of protection, probably induced by recent exposure to seasonal influenza, may not be mediated by hi or neutralizing antibody. in contrast, strain-specific immunity, most often mediated by hi or neutralizing antibodies can be so long-lasting that after several decades it will still provide significant protection against any closely-related virus that re-appears in the population. it has not escaped our notice that although attack-rates in the h n pandemic were low in many countries, with generally mild symptoms, the virus did cause lifethreatening illness in a small proportion of younger affected persons. it seems likely that those who were most severely affected in were doubly unlucky: they had missed out on seasonal influenza infection or vaccination in the preceding season(s), and they were born too late to have been protected by the closely-related viruses that are thought to have circulated before . during the early phases of the influenza pandemic in italy, real-time modeling analysis were conducted in order to estimate the impact of the pandemic. in order to evaluate the results obtained by the model we compared simulated epidemics to the estimated number of influenza-like illness (ili) collected by the italian sentinel surveillance system (influnet), showing a good agreement with the timing of the observed epidemic. by assuming in the model mitigation measures implemented in italy, the peak was expected on week ( % ci: , ). results were consistent with the influnet data showing that the peak in italy was reached in week . these predictions have proved to be a valuable support for public health policy makers for planning interventions for mitigating the spread of the pandemic. mathematical models have recently become a useful tool to analyse disease dynamics of pandemic influenza virus can-didates. [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] as of april , after the pandemic threat emerged worldwide, it was crucial for policy makers to have early predictions on the possible spread of the pandemic influenza virus in order to support, with quantitative insight into epidemic, policy decisions. thus, after the first pandemic alert was announced by the world health organization (who) in late april , a national crisis management committee headed by the minister of health was established in italy in order to provide weekly advice to the italian ministry of health. real-time analyses using an individual based model were undertaken. the transmission model was previously used for evaluating the effectiveness of the control measures adopted in the national pandemic preparedness plan and for assessing the age-prioritized distribution of antiviral doses during an influenza pandemic. to parameterize the transmission model, we used data derived from the national surveillance system until june and estimates of key epidemiological parameters as available at that time. in order to provide a preliminary assessment of the model predictions performed during the early stages of the epidemic, we compare model predictions with surveillance data of influenza-like illness (ili) available since august . after the first pandemic alert was announced by the who in late april , a national active surveillance system for the pandemic influenza was set up from april to july . however, over the period from april to october , surveillance systems, laboratory testing, and diagnostic strategies have varied considerably in italy. since end of july , following who recommendations, the focus of surveillance activities has changed in reporting requirements, as active case-finding became unsustainable and unnecessary. for this reason, the ministry of health (ministry of health, available in italian at the website: http://www.normativasanitaria.it) requested regional health authorities to report the weekly aggregated ili cases according to a new case definition (sudden onset of acute respiratory symptoms and fever > °c plus at least one of the following systemic symptoms: headache, malaise, chills, sweats, fatigue; plus at least one of the following respiratory symptoms: cough, sore throat, nasal obstruction). by october , following the increasing number of cases, the sentinel influenza surveillance system (influ-net available at: http://www.flu.iss.it) became the official surveillance system for ili cases in italy (ministry of health, available in italian at the website: http://www. normativasanitaria.it). since , influnet is routinely based on a nation-wide, voluntary sentinel network of sentinel community based physicians in the regions and autonomous provinces of the country. incidence rates are, therefore, not based on consultations, but on the served population of each reporting physician each week. influ-net usually consists of an average of (range - ) general practitioners (including physicians and pediatricians) per year, covering about ae - % of the general population, (representative for age, geographic distribution, and urbanization level) reporting ili cases (according with a specific case definition). italian influnet surveillance system is part of the european influenza surveillance scheme (eiss). a stochastic, spatially explicit, individual-based simulation model was used. individuals are explicitly represented and can transmit the infection to household members, to school ⁄ work colleagues, and in the general population (where the force of infection is assumed to depend explicitly on the geographic distance). the national transmission model was coupled with a global homogeneous mixing susceptible-exposed-infectious-removed (seir) model accounting for the worldwide epidemic, which is used for determining the number of cases imported over time. regarding the epidemiological assumptions (e.g., length and shape of the infectivity period, which lead to an effective generation time of ae days), this study is consistent with refs [ , , , ] , but for the proportion of symptomatic individuals, which is assumed to be ae %. the basic reproductive number of the national transmission model was set to ae , according to the early estimates as obtained during the initial phase of the epidemic in mexico in a community setting. , we initialized our simulations through the global homogeneous mixing model in such a way that imported cases were generated until june . this gives a reliable way for fixing the time in the simulations and thus determining the timing of school closure and vaccination in the simulations. the model accounts for school closure for both summer and christmas holidays: we assumed that in these periods contacts among students decrease, while contacts in the general community increase, as in ref. [ ] . we also considered scenarios accounting for partial immunity in the population. in order to investigate the effects of recommendations of the ministry of health (confirmed cases coming from affected areas were isolated for - days, either in hospital or at home) established in the early phase of the pandemic (april-july ), we assumed that a fraction of the imported symptomatic cases were isolated on the first day after the symptoms onset. this recommendation was in place until july . we also assumed, according to the italian school calendar, that schools were closed from june to september for the summer holidays, and from december to january for christmas holidays. the effects of prolonged school closure were also investigated. when considering vaccination, we assumed weeks for the logistical distribution of doses of pandemic vaccine. since at the time of simulation specific recommendations regarding the administration of a single dose of pandemic vaccine from ema were not available yet, we considered the administration of vaccine doses month apart). the pandemic vaccine was considered effective after the administration of the second dose with a vaccine efficacy of %. we assumed the vaccine to be administered by priority, vaccinating first the target population accounting for essential services workers (including health care workers and blood donors), pregnant women at the second or third trimester, and at risk patients (with chronic underlying conditions) younger than years old. the vaccination coverage was assumed %. regarding antiviral treatment and prophylaxis, recommendations of the ministry of health in the initial phase of the epidemic were to administer antivirals to all confirmed cases and to their close contacts. we assumed that the surveillance system would be able to detect % of symptomatic cases. after july , recommendations changed and antiviral treatment was considered only for cases with severe complications and in case of local clusters. since it was difficult to establish the proportion of treated cases, we considered different scenarios: antiviral treatment from % to % of the symptomatic cases. consistently with ref. [ ] , both treatment and prophylaxis were assumed to start day after the clinical onset of symptoms in the index case. treatment was assumed to reduce infectiousness by %, whereas antiviral prophylaxis was assumed to reduce susceptibility to infection by %, infectiousness by %, and the occurrence of symptomatic disease by %. as of july , approximately confirmed cases have been reported to the italian surveillance system for pandemic influenza. during july, the sudden increase of ili confirmed cases suggests for sustained autochthonous transmission in italy. by analyzing the number of ili cases reported to the surveillance during the weeks from to , we found that the exponential growth rate was ae ⁄ week and thus we estimated the national reproductive number to be r = ae . this estimate of the basic reproductive number supports the choice of the value adopted in the model simulations (r = ae ). in the absence of intervention measures, the predicted cumulative attack rate was ae % ( % ci: ae , ae ), and the peak was expected on week ( % ci: , ) with a peak day incidence of ae % ( % ci: ae %, ae %). by assuming case isolation, antiviral treatment, and prophylaxis to % of symptomatic cases until july , the peak was expected on week ( % ci: , ). when considering ae % of natural immunity in the population aged more than years, the peak was expected week later than in the previous scenario, i.e., on week ( % ci: , ). to validate the model, we compared model predictions (which are based only on the available information on the early phases of the epidemic) with ili data (figure ). based on model predictions, we estimated the underreporting factor of influnet ranging from ae to ae , considering different scenarios. by aligning the simulations with the ili data adjusted by the underreporting factor, we can observe that almost all the points in the increasing phase of the epidemic lie within the % ci of the model results (both considering or not natural immunity). the decay phase of the simulated epidemics shows a small delay with respect to the ili data. when introducing single and combined mitigation measures, such as case isolation, antiviral treatment, prophylaxis, and vaccination in the model, results showed that even a low proportion of symptomatic cases treated with antiviral drugs could have led to a relevant reduction in the epidemic size (table ) . we simulated the planned italian vaccination strategy (begun on october ), obtaining a limited but not negligible reduction in the attack rate with respect to the scenarios accounting only for antiviral treatment. moreover, the effect of vaccination would be higher if coupled with antiviral treatment; vaccination would have no effect on delaying the peak incidence. model predictions produced in italy during the early phase of the pandemic influenza are in excellent agreement with italian surveillance data on the beginning of the epidemic (when case isolation, antiviral treatment of index cases, and antiviral prophylaxis to close contacts were implemented by the italian regional public health authorities) and are basically consistent with the influ- net data during the course of the epidemic. the model has been useful for predicting the timing of the epidemic, while it has overestimated the impact of the influenza pandemic for adult and elderly individuals. however, the disalignment is probably due to the model parameterization. based on literature values, , we assumed a similar fraction of cases in the different social contexts considered in the model (namely ⁄ in households, ⁄ in schools ⁄ workplaces, and ⁄ in the general community), since analysis on the relative transmissibility of the virus was not carried out for any country yet. we were also able to estimate an underreporting factor for the influnet data in the range ae - ae . if we focus our attention on the reporting factor computed by considering the total number of cases (instead of symptomatic cases), the resulting value lies in the range - ae %, which is in excellent agreement with the range estimated in ref. [ ] on previous a ⁄ h n influenza seasons, namely ae %- ae %. moreover, based on our results showing that vaccinating % of the italian population was more than adequate to mitigate the pandemic, the ministry of health decided to stockpile a limited number of vaccines. we have also shown that starting the vaccination program in october (or later) could have had only a limited effect on reducing the impact of the epidemic, although it may have been useful to prevent a possible second wave and to protect essential workers and at-risk patients. finally, our results have shown that antiviral treatment would have been the most efficient strategy to reduce the impact of the influenza pandemic, even with a limited antiviral stockpile. a population-wide passive immunotherapy program in this paper, we assume that convalescent plasma (cp) is efficacious in treating severe cases of pandemic influenza. under this premise, we test the hypothesis that a population-wide passive immunotherapy program that collects plasma from a small percentage of convalescent individuals can harvest sufficient cp to treat a substantial percentage of severe cases during the first wave of the pandemic. the proposed program involves recruiting adults (individuals age - years) to donate blood if they have experienced influenza-like symptoms more than weeks ago (to account for the time needed for neutralizing antibodies to build up). the blood samples would be screened for infectious diseases (including hiv, hbv, hcv, htlv, and syphilis, etc., as in routine blood donation screening) and neutralizing antibodies against the pandemic virus. donors whose blood samples are free of known infectious agents and contain a sufficiently high titer of neutralizing antibodies would then be invited to donate plasma by plasmapheresis or routine whole blood donation. qualified donors with higher titers may be given higher priority for plasma donation. in this paper, we use the demographic and logistical parameters of hong kong as a case study. see figure for a schematic of the proposed passive immunotherapy program. we examine the following questions regarding the logistical feasibility and potential benefits of the proposed passive immunotherapy program: (i) what percentage of convalescent individuals (donor percentage) is needed in order for the program to significantly reduce pandemic mortality? (ii) how many severe cases can be offered passive immunotherapy? (iii) what are the ratelimiting factors in the supply of passive immunotherapy? (iv) what are the epidemiologic and logistical factors that determine the demand-supply balance of passive immunotherapy? a more detailed presentation of our results is now available in ref. [ ] . transmission and natural history model for pandemic influenza we use an age-structured disease transmission model to simulate the spread of pandemic influenza. the natural history model is similar to that used by basta et al. , the most important parameter in characterizing the growth of an epidemic is the basic reproductive number r , which is defined as the average number of secondary cases generated by a typically infectious individual in a completely susceptible population. we consider values of r between ae and , which is consistent with recent estimates. , [ ] [ ] [ ] logistical model for the passive immunotherapy program we assume that q d (%) of to year-old individuals who have recovered from symptomatic infections of pandemic influenza donate their blood for screening t r = days after cessation of symptoms. follow-ups of convalescent individuals infected with h n pdm in an ongoing clinical trial of passive immunotherapy suggested that neutralizing antibodies level reaches maximal level around - days after recovery and stays at that level for months after. we assume that q s (%) of these donors are qualified for plasma donation of which q r (%) are recurrent donors who return to donate plasma every t w = days. screening involves both detection of infectious agents and neutralizing antibodies against the pandemic virus. the latter is the rate-limiting step because neutralization tests of pandemic viruses can only be done in a bsl setting. we assume that five bsl -trained technicians are available to test the blood specimens, each running viral neutralization tests in days. therefore, the capacity and turnaround time of blood screening are u s = and t s = days, respectively. hong kong currently has nine plasmapheresis machines which allow a maximal throughput of plasma donations per day (assuming -hour daily operation with each donation taking minutes). therefore, the capacity and turnaround time of plasmapheresis are u p = and t p = ⁄ days, respectively. collected cp are ready for use in transfusion after final quality check, which takes t q = days. we assume that r t plasma donations are required to treat one severe case on average. the expert panel of the abovementioned study of passive immunotherapy for h n pdm in hong kong suggested that r t < . we assume that p h (%) of symptomatic cases will be severe cases for whom passive immunotherapy is suitable. although p h will be smaller than the case-hospitalization rate (passive immunotherapy may not be suitable for some hospitalized cases), we assume that the two have similar ranges and consider p h ranging from ae % to %. because each severe case requires r t plasma donations on average, demand for cp is simply r t p h times the number of symptomatic cases. therefore, r t p h can be regarded as a single parameter, which we refer to as the lumped demand parameter. we define the outcome as the percentage of severe cases that can be offered passive immunotherapy by the proposed program during the first wave of the local epidemic. we refer to this outcome as treatment coverage and denote it by q. we consider the base case scenarios assuming q r = % and q s = %. in general, the treatment coverage q increases sharply as the basic reproductive number r and the lumped demand parameter r t p h decrease (figure a ). in particular, when r is large and r t p h is small, q is very sensitive to r t p h , but insensitive to r . similarly, when r and r t p h are small, q is very sensitive to both. with a donor percentage of q d = %, the proposed program can supply passive immunotherapy to more than % of severe cases (q > %) if r < ae and r t p h < ae %, but < % if r > ae and r t p h > ae %. in general, the treatment coverage q increases sharply as the donor percentage q d rises from %, but with rapidly decreasing marginal increase ( figure b ). when r < ae and r t p h < ae %, q > % even if q d is as low as %, which is comparable to the current average blood donation rate of ae donations per population in developed countries. when q d is > %, q becomes largely insensitive to further increase in q d in most scenarios. the treatment coverage q for q d = % is more than % that for q d = % across all values of r and r t p h considered in the base case. therefore, increasing the donor percentage q d beyond % has a relatively small impact on cp supply. this is because increasing q d can boost supply only when plasmapheresis is not yet the supply bottleneck. for the same reason, once the donor percentage q d has reached %, the treatment coverage q is insensitive to further increase in q d even when the plasmapheresis and screening capacity are doubled ( figure b , lower panel). we conduct an extensive multivariate sensitivity analysis to test the robustness of our base case observations against uncertainties in parameter values. we generate epidemic scenarios by randomly selecting parameter values from their plausible ranges using latin-hypercube sampling. although there are numerous model parameters, the treatment coverage q is mainly determined by three lumped parameters: (i) r t p h , which indicates the magnitude of demand; (ii) q s q d , which indicates the magnitude of supply; (iii) the initial growth rate of the epidemic r (results not shown). while the dependence of q on r t p h and q s q d is readily comprehensible, it is not obvious a priori that q depends on the natural history and transmission dynamics of the disease via only the initial epidemic growth rate. when the plasmapheresis and screening capacity are very large, the supply-demand dynamics is further simplified: the treatment coverage q depends on lumped demand parameter r t p h and the lumped supply parameter q s q d only via their ratio. finally, q becomes insensitive to q s q d when the latter increases beyond - %, which is consistent with our base case observations. our results suggest that with plasmapheresis capacity similar to that in hong kong, the proposed passive immunotherapy program can supply cp transfusion to treat - % of severe cases in a moderate pandemic (basic reproductive number r < ae , lumped demand parameter r t p h < ae %) when the donor percentage is - %. increasing the donor percentage beyond % has little additional benefit because cp supply is constrained by the capacity of plasmapheresis during most stages of the epidemic. increasing plasmapheresis capacity could significantly boost cp supply, especially when there is a substantial pool of recurrent donors to alleviate the dependence of cp supply on donor percentage. in an ongoing clinical trial of passive immunotherapy for h n pdm virus infection in hong kong, % of convales- cent individuals agreed to donate their plasma for the study. therefore, the donor percentage required by the proposed passive immunotherapy program ( - %) is likely to be feasible. in view of the logistical feasibility of such program, we recommend that further clinical studies are conducted to evaluate the safety and efficacy of passive immunotherapy as a treatment for severe cases of pandemic influenza virus infection. our study is based on the premise that cp will be efficacious in reducing morbidity and mortality associated with pandemic influenza. in theory, the polyclonal nature of neutralizing antibodies in cp would lower the probability of an escape mutant emerging in treated patients. further, besides providing neutralizing antibodies against the pandemic virus, cp also might carry antibodies to other bacterial pathogens, which might decrease the severity of coexisting bacterial infections. as such, cp not only might reduce the case fatality rate but might also increase the recovery rate and shorten duration of hospitalization of severe cases. the proposed passive immunotherapy program can thus significantly reduce the burden on the healthcare system, especially the intensive care unit, which will likely be stressed, if not overloaded, at the peak of an influenza pandemic wave, hence benefiting the general public and not only those receiving passive immunotherapy. although the hypothesized efficacy of cp has yet to be proven in clinical trials, our modeling results show that a public health system similar to that in hong kong has the capacity to support a population-wide passive immunotherapy program that can supply cp treatment to a substantial percentage of the severe cases in a moderately severe pandemic. we estimate that compared to other developed countries, hong kong has a relatively low plasmapheresis capacity. our conclusions regarding donor percentage needed and rate-limiting factors remain valid for plasmapheresis capacity ranging from % to % of what we have assumed in the base case (results not shown). our conclusions are robust against uncertainties in the natural history and transmission dynamics of pandemic influenza. our sensitivity analysis shows that the outcome depends on these epidemiological characteristics only via the initial growth rate of the epidemic. as such, our results are applicable not only to pandemic influenza, but also to other emerging infectious diseases for which the time-scales of disease transmission and antibody response are similar to that for influenza virus. the three determinants of treatment coverage (the initial epidemic growth rate, the lumped demand parameter r t p h , and the lumped supply parameter q d q s ) are all readily measurable in real-time during an epidemic. therefore, our methods and results can be used as a general reference for estimating the treatment coverage of the proposed passive immunotherapy program for a given plasmapheresis capacity. background highly pathogenic h n virus continues to pose a serious threat to human health and appears to have the capacity to cause severe disease in previously healthy young children and adults. at present, antiviral therapy by oseltamivir remains the mainstay for managing h n patients. while early treatment improves survival, approximately % of patients treated within days of illness still succumb to the disease. in addition to the role of viral replication, there is good evidence that the host proinflammatory responses contributes to h n pathogenesis. this suggests that both antiviral and immune-modulatory drugs may have a role in therapy. we previously demonstrated that cyclooxygenase (cox- ) plays a regulatory role in h n hyperinduced pro-inflammatory responses, and its inhibitor has potent effects at modulating this host response. now we demonstrate that, in addition to its immune-modulatory effect, a selective cox- inhibitor, ns- has a direct antiviral effect against h n infection. materials and methods human primary monocytederived macrophages or alveolar epithelial cells (a ) were pre-treated with ns- or drug-vehicle for hour before h n virus infection. h n viruses at multipicity of infection (moi) of was used to infect the cells. following virus adsorption for mins, the virus inoculum was removed, and the cells were washed and incubated in corresponding medium with ns- or drug-vehicle as controls for , , , , and hours post-infection. cells were harvested for rna isolation at hours post-infection to study viral matrix (m) gene expression. supernatants were collected for % tissue culture infection dose (tcid ) assay to determine the virus titers at , , , and hours after h n infection. results ns- was found to suppress virus gene transcription and infectious virus yield in h n -infected human cells. conclusion we demonstrate that a selective cox- inhibitor, ns- , shows an inhibitory effect on h n viral replication in addition to its immune-modulatory effect that could counter the detrimental effects of excessive proinflammatory cytokine production. the findings suggest that selective cox- inhibitors may be a therapeutic target for treating h n disease in combination with appropriate antiviral therapy. the emergence and spread of the highly pathogenic avain influenza viruses (h n ) in poultry and wild birds with repeated zoonotic transmission to humans has raised pandemic concern. at the time of writing, human cases have been reported with fatalities, an overall case fatality rate of around % (cumulative number of confirmed human cases of avian influenza a ⁄ (h n ) reported to world health organization updated to october ). our previous data demonstrated that cox- was markedly up-regulated in h n -infected primary human macrophages, and that it played a regulatory role in the h n hyperinduced host pro-inflammatory responses. such cytokine dysregulation is proposed to be a major contributor to the pathogenesis of h n disease in humans. with the use of selective cox- inhibitors, we found that the h n -hyperinduced cytokine response was significantly suppressed by the drug in a dose-dependent manner. selective cox- inhibitor is a form of a non-steroidal anti-inflammatory drug that selectively targets cox- , and it is an inducible enzyme responsible for inflammatory process and immune response. here, we report a novel finding of a direct antiviral effect of a selective cox- inhibitor, ns- , against h n infection in human primary macrophages and alveolar epithelial cells. taken together with our previous findings that suggest an immuno-modulatory effect that can modulate virus driven cytokine dysregula-tion, these findings highlight a role for cox- and its downstream signaling as potential novel targets for adjunctive therapy of severe viral pneumonia, such as that caused by h n . such therapy may be combined with conventional antiviral drugs. the h n virus used was a ⁄ vietnam ⁄ ⁄ ( ⁄ ) (h n ), a virus from a patient with h n disease in vietnam during . the viruses were grown and titrated in madin-darby canine kidney cells cells as described elsewhere. virus infectivity was expressed as tcid . all experiments were performed in a biosafety level facility. monocyte-derived macrophages: peripheral-blood leucocytes were separated from buffy coats of healthy blood donors (provided by the hong kong red cross blood transfusion service) by centrifugation on a ficoll-paque density gradient (pharmacia biotech) and purified by adherence as reported previously. the research protocol was approved by the ethics committee of the university of hong kong. macrophages were seeded onto tissue culture plates in rpmi medium supplemented with % heat-inactivated autologous plasma. the cells were allowed to differentiate for days in vitro before use in the infectious experiments. alveolar epithelial cells: a cells were obtained from atcc and maintained in culture using dulbecco's modified eagle medium supplemented with % fetal calf serum, . mg ⁄ l penicillin, and mg ⁄ l streptomycin. differentiated macrophages or a cells were pre-treated with a selective cox- inhibitor, ns- (cayman), at concentrations as indicated or drug-vehicle for hour before infection. cells were infected with h n viruses at moi of . following virus adsorption for min, the virus inoculum was removed, the cells were washed and incubated in corresponding medium with ns- or drug-vehicle as controls throughout the experiments. cells were harvested for rna isolation at hours post-infection to study viral m gene expression. supernatants were collected for tcid assay to determine the virus titers at , , , and hours after h n infection. total rna was isolated using the rneasy mini kit (qiagen) according to the manufacturer's instructions. the cdna was synthesized from mrna with poly(dt) primers and superscript iii reverse transcriptase (invitrogen). transcript expression was monitored by real-time pcr using power sybr Ò green pcr master mix kit (applied biosystems) with specific primers. the fluorescence signals were measured using the real-time pcr system (applied biosystems). the specificity of the sybr Ò green pcr signal was confirmed by melting curve analysis. the threshold cycle (ct) was defined as the fractional cycle number at which the fluorescence reached times the standard deviation of the base-line (from cycle to ). the ratio change in target gene relative to the b-actin control gene was determined by the )ddct method as described elsewhere. ns- reduced the viral m gene expression in h n infected human macrophages in a dose-dependent manner ( figure ) . similarly, production of infectious virus yield in h n infected macrophages was found to be suppressed in the presence of ns- at lm compared to vehicletreated cells (figure a) . a comparable effect of ns- was observed in h n -infected human alveolar epithelial cells ( figure b ). we have previously demonstrated that cox- expression was dramatically upregulated following h n infection in human macrophages in vitro and in epithelial cells of lung tissue samples obtained from autopsy of patients who died of h n disease. this suggests that cox- may be an important host factor involved in h n pathogenesis and also provide a possible explanation on why h n virus replication is susceptible to a selective cox- inhibitor. cox- was previously reported to play an important role in the pathogenesis of other influenza a viruses. an in vivo study has highlighted the importance of cox- in h n - infected mice. findings showed that infection induced less severe illness and reduced mortality in cox- knock-out mice than in wild-type mice. on the other hand, cox- knock-out mice had enhanced inflammation and earlier appearance of proinflammatory cytokines in the bal fluid, whereas the inflammatory and cytokine responses were dampened in cox- knock-out mice. these data suggests that cox- and cox- may lead to opposite totally contrasting effects on influenza h n infected mice. cox- deficiency is detrimental, whereas cox- deficiency is beneficial to the host during influenza viral infection. therefore in the present study, instead of blocking cox enzymes in general as reported by others, we have chosen ns- that selectively block cox- but preserve cox- activity and showed that this drug significantly reduced h n virus replication in a dose-dependent manner. taken together with our previous report suggesting its immuno-modulatory effects, we believe that selective cox- inhibitors and cox- signaling pathways deserve investigation as a promising approach for targeting therapy in h n diseases. however, a few reports have suggested the importance of cox- in the late stage of inflammation for the resulution of inflammation, [ ] [ ] [ ] and this raises concern whether inhibition of cox- may be harmful in treating diseases related to dysregulation of host inflammatory response such as acute lung injury, which is a leading cause of death in h n patients. we previously looked at the autopsy samples of lung tissues from h n patients and found that cox- expression was markedly up-regulated compared with that from persons who died of non-respiratory causes. moreover, data also demonstrated that pro-inflammatory cytokines, such as tnf-a, was markedly elevated in the h n infected lung autopsies. taken together, with the histo-pathological findings, which showed predominant features of exudative inflammatory phase in autopsy lung samples from h n patients, , we may therefore speculate that people who had fatal h n infection died during acute inflammation phase, and before the resolution could occur, especially for the cases with a short disease duration (< - days). in conclusion, the roles of cox- in both pro-inflammation and pro-resolution phases deserves detailed investi-gation. the timing of selective cox- inhibitor therapy in h n infected patients may be extremely critical. therefore a time-dependent study using selective cox- inhibitors on h n -infected animal models will be particularly important in order to address the effectiveness of this drug in treating h n disease. avian antibodies to combat potential h n pandemic and seasonal influenza highly pathogenic avian influenza a virus (hpaiv) strain a ⁄ h n with unprecedented spread through much of asia and parts of europe in poultry remains a serious threat to human health. passive immunization (transfer of protective immunoglobulins) offers an alternative and ⁄ or additional strategy to prevent and cure influenza. here, we report that virus-specific immunoglobulin y (igy) isolated from eggs of immunized hens provide protection in mice against lethal h n virus infection by neutralization of the viruses in the lungs upon intranasal administration. importantly, chicken eggs obtained from randomly selected supermarkets and farms in vietnam, where mass poultry vaccination against a ⁄ h n is mandatory, contain high levels of igy specific for a ⁄ h n virus. when administered before or after the infection, igy prevented and significantly reduced replication and spread of hpaiv h n and related h n strains. thus, the consumable eggs readily available in markets of countries that impose poultry vaccination against a ⁄ h n could offer an enormous source of valuable biological material that provides protection against a ⁄ h n virus with pandemic potential. the approach could be used to control seasonal influenza. since , hpaiv of the h n subtype has resulted in more than cases of laboratory-confirmed human infection in countries with a death rate of more than % (http://www.who.int/csr/disease/avian_influenza/). h n influenza virus remains a global threat because of its continued transmission among domestic poultry and wild birds. passive immunization (the transfer of antigen-specific antibodies (abs) to a previously non-immune recipient host) offers an alternative and ⁄ or additional countermeasure against influenza. development of human monoclonal antibodies (mabs) against h n influenza haemagglutinin (ha) using epstein-barr virus (ebv) immortalization of b cells isolated from patients infected with h n , phage display, humanized mabs, and human recombinant abs has been attempted. chickens produce a unique immunoglobulin molecule called igy that is functionally equivalent to mammalian igg. igy is found in the sera of chickens and is passed from hens to the embryo via the egg yolk. egg igy has been used to prevent bacterial and viral infections (see review ) of the gastrointestinal tract and recently for protection against pseudomonas aeruginosa infection of the respiratory tract of patients with cystic fibrosis (cf). the epidemic of hpaiv h n virus has resulted in serious economic losses to the poultry industry, mostly in southeast asia. therefore, many countries including china, indonesia, thailand, and vietnam have introduced mass vaccination of poultry with h n virus vaccines that controls the h n epidemic to some extent. chickens immunized with recombinant h and ⁄ or inactivated h n reassortant vaccines produced a high level of virus-specific serum antibodies (abs) and were protected from h n virus challenge. theoretically, these abs could be found in egg yolk and separated for use in humans to prevent and cure h n hpaiv infection and disease, respectively. here, we examined the possibility that igy isolated from consumable eggs available in supermarkets in vietnam, where mandatory h n vaccination has been implemented, provide prophylaxis and therapy of hpaiv h n infection in mice. six-to -week-old female balb ⁄ canncrl (h- d) mice (charles river and jackson laboratory) and hy-line . igy abs were extracted from egg yolks as previously described. the % egg infectious dose (eid ) was determined by serial titration of virus stock in eggs, and eid ⁄ ml values were calculated according to the method of reed and muench. human virus stocks were grown in mdck cells as described previously , with viral titers determined by standard plaque assay. the % tissue culture infectious dose (tcid ) of virus was determined by titration in mdck cells. the standard elisa was performed for detection of anti-igy in the sera of igy-immunized mice. fifty percent lethal dose (ld ) titers were determined by inoculating groups of eight mice i.n. with serial -fold dilutions of virus as previously described. for infection, ketamine-anesthetized mice were inoculated intranasally with a lethal dose with pfu ( · ld ) of a ⁄ pr ⁄ ⁄ (h n ) virus as previously described, · ld of vn ⁄ (h n ) or · ld a ⁄ aquatic bird ⁄ korea ⁄ w ⁄ (h n ) resuspended in ll pbs per animal. ketamine-anesthetized mice were treated intranasally with ll of igy before or after infection. mice were observed for weight loss and mortality. subsets of animals were scarified for virus titre. we found comparable hai titers in the sera and egg yolks obtained from a farm in vietnam that was participating in a national mass vaccination program. furthermore we found % of eggs purchased in randomly selected supermarkets in hanoi, vietnam containing h -specific igy. the hai and vn titers of pooled egg yolk igy are comparable with those of sera obtained from hens selected randomly from the farm that underwent supervised h n vaccination. in contrast, igy separated from eggs purchased in korean markets where poultry are not vaccinated against avian influenza h n has no detectable h -specific hai or vn activity. we first treated naïve mice intranasally with h n -specific igy before infection with hpaiv h n strain, a ⁄ vietnam ⁄ ⁄ , isolated from a fatal case. such treated mice displayed mild weight loss and recovered completely by the end of the first week after inoculation ( figure a ). when animals were treated once with h n specific igy after h n inoculation they exhibited minimal weight loss during the first week after inoculation, and virus titers in the lungs were substantial reduced at day after infection; however, % of treated mice succumbed to infection during the second week after inoculation ( figure b) . it is possible that not all the hpaiv a ⁄ h n viruses were neutralized upon the single treatment with igy, and escaping viruses can spread systemically to organs outside of the lungs. these viruses may reappear in lung tissue later when specific igy is absent. indeed, vn ⁄ virus injected intravenously or into the brain can spread to the lungs. to circumvent the virus escape, we administered multiple treatments with h n specific igy after the infection. as a result, all infected mice recovered completely by the second week post-infection ( figure c) , and virus titers in the lungs were substantially reduced to the level that seen in protected mice that received single prior-infection treatment ( figure d) . similarly, the protective efficacy of h n -specific igy was observed in mice infected with lethal dose of mouseadapted avian influenza virus strain a ⁄ aquatic bird ⁄ korea ⁄ w ⁄ (h n ). this virus shares . % nucleotide sequence homology with ha (h ) but has different na (n ) from the one used for mass immunization in vietnam (reassortant avian h n influenza virus a ⁄ goose ⁄ gd ⁄ -derived, strain re- ). the results indicate that h n -specific igy isolated from eggs purchased in markets have preventive and therapeutic effects against infection with hpaiv h n and the related strain h n . the findings suggest that while a single treatment with igy prior to lethal infection was sufficient to protect the animals from the infection, multiple treatment is required for complete therapeutic effect after infection with hpaiv such as vn ⁄ strain. we further examined the protective efficacy of igy isolated from eggs laid by hens immunized in the laboratory with heat-inactivated human influenza a ⁄ h n virus, a ⁄ pr ⁄ ⁄ . we found substantial levels of hai and vn abs in the sera and yolks derived from immunized hens. when naïve mice were administered intranasally with such anti-pr ⁄ igy at - hours before or after infection with lethal dose of pr ⁄ virus, they were protected from the infection or lethal disease, respectively. the virus titers in the lungs of a ⁄ pr specific igy-treated mice at day after infection were also significantly lower than those seen in untreated mice or mice receiving normal igy. intranasal administration is the most effective route as compared to oral or peritoneal or intravenous administration for protection against lethal challenge, and the presence of virus-specific igy in bronchoalveolar lavage (bal) is required for the protection. the results provide a proof-of-concept that intranasal administration of virus-specific igy prevents influenza virus infection and cures the disease. the concept could be applied to control influenza outbreaks including seasonal and pandemic influenza. the protection was correlated with hai and vn activities of the igy and reduced virus titers in the lungs after treatments, suggesting that the protection is mediated by vn. we asked if administration of igy in the respiratory tract induces anti-igy ab response in mice. if this is the case, the next question is whether pre-existing anti-igy abs block igy-mediated protection. indeed, significant levels of anti-igy were observed in animals that received single or multiple administration of igy. when igy-immune mice were treated with virus-specific igy before or after lethal challenge, the results were identical to those obtained from treated naive mice, indicating that pre-existing anti-igy abs do not interfere with the protection mediated by virus-specific igy. consistently, incubation with anti-igy serum did not interfere with hai and vn activity of the virus-specific igy, indicating that anti-igy abs do not block virus binding by virus-specific igy (figure ). the finding suggests that the igy treatment could be applied to persons who have developed anti-igy during the individuals' life, and such treatment strategy could be repeated if multiple treatment is required and ⁄ or necessary later on to protect infections with other pathogens. the approach using specific igy for prevention and therapy of hpaiv h n infection offers a practical alternative to immunotherapy using convalescent plasma and an additional therapeutic option to antiviral drugs since widespread drug resistance has been recently reported among influenza virus strains. igy is relatively stable. we found no change in protective activity after at least months storage at °c, and lyophilization does not affect the activity, making production of igy practical. the use of igy immunotherapy has many advantages, since igy does not activate the human complement system or human fc-receptors, which all are well-known cell activators and mediators of inflammation. we chose the water dilution method for preparation of igy. the method is simple, efficient and does not require any toxic compounds or any additives. such igy preparations by this method have been used in other human study. , eggs are normal dietary components, so there is minimal risk of toxic side effects, except for those with egg allergy. thus, our study demonstrated that influenza virus-specific igy can be used in passive immunization that provides great help for immunocompromised patients and elderly who have weaken immune response to influenza vaccines. importantly, the consumable eggs readily available in the markets of countries that impose mandatory h n vaccination offer an enormous source of valuable, affordable, and safe biological material for prevention and protection against potential h n pandemic influenza. parts of the information and data presented in this manuscript were previously published in http://www.plosone.org/ article/info:doi% f . % fjournal.pone. . the polyphenol rich plant extract cystus is highly introduction the ⁄ h n influenza a virus pandemic clearly demonstrates that influenza is still a major risk for the public health. although the pandemic swine origin influenza a virus (soiv) caused only mild symptoms, the control of the outbreak still remains difficult. even as vaccine is available against this virus, the possibility of reassortment between the pandemic and a seasonal or avian a ⁄ h n influenza virus strain is indeed a frightening, but a likely event. this reassortant strain might be able to transmit easily between humans causing fatal infections, and the current soiv vaccine might no longer be sufficient to protect against the reassorted virus. in such a case, we can only rely on effective antiviral drugs. today, neuraminidaseinhibitors, such as oseltamivir, represent the most common clinically approved medication against influenza a viruses. unfortunately, the frequency of reports describing the appearance of drug-resistant seasonal h n and also h n influenza a viruses dramatically increased in the recent past. [ ] [ ] [ ] [ ] drug resistance to the known antivirals highlights the urgent need for alternative antiviral compounds with novel defense mechanisms. recently, we have reported that a polyphenol rich plant extract, cystus , which showed antiviral activity against influenza a viruses in cell culture and in mice. , moreover, the antiviral activity of cy-stus against seasonal influenza virus and common colds was also demonstrated in humans. however, the efficiency of cystus against soiv and a ⁄ h n isolates was unknown so far. therefore, we investigated cy-stus effectiveness against the pandemic strain and seven natural influenza a ⁄ h n isolates detected in several avian species during ⁄ avian influenza outbreak. additionally, the potency of the most common neuraminidase inhibitor oseltamivir was also investigated against these isolates. here, we show that cystus treatment was effective in in vitro studies against soiv and a ⁄ h n influenza virus. viruses avian h n isolates were originally obtained from the bavarian health and food safety authority, oberschleissheim, germany. the soiv a ⁄ hamburg ⁄ ⁄ was obtained from the robert-koch-institut, berlin, germany. all h n viruses were further propagated in embryonated chicken eggs or mdck ii (h n v) cells at the friedrich-loeffler-institut, tübingen, germany. for the cytopathological effect (cpe) inhibition screening, in accordance with sidwell, mdck ii cells were infected with different viruses at moi of ae . virus-infected cells were then treated with antiviral compounds cystus from ae to lg ⁄ ml or oseltamivir from ae nm to mm. after incubation for hours at °c and % co , cells were fixed, and viable cells were stained with crystal violet. after extraction of crystal violet from viable cells with % methanol, the extinction was measured with an elisa reader. immediately before infection, mdck ii cells ( · cells ⁄ well) were washed with pbs and subsequently incubated with virus diluted in pbs ⁄ ba ( ae % ba) mm mgcl , ae mm cacl , penicillin and streptomycin to a multiplicity of infection (moi) of ae for minutes at °c. cystus was added in a concentration of lg ⁄ ml directly to the virus-stock and on the cell monolayer simultaneously with the infection. after minutes incubation period, the inoculums were aspirated and cells were incubated with either mem or mem containing lm oseltamivir. at indicated time points, supernatants were collected. infectious particles (plaque titers) in the supernatants were assessed by a plaque assay under avicel as described previously. in order to investigate the antiviral potential of cy-stus , ec values based on the inhibition of the cpe on mdck ii cells were determined for cystus and in addition for oseltamivir. the ec values for cystus ranged from ae to ae lg ⁄ ml. cystus demonstrated the highest sensitivity against the soiv, sn and mb isolates with ec values below lg ⁄ ml. compared to these virus strains, cystus showed a slightly increased ec value for gsb ( ae lg ⁄ ml). in contrast the ec values for bb and bb were notably elevated ( ae and ae lg ⁄ ml). thus, the weakest antiviral effect of cystus was observed against these two isolates. the ec values evaluated for oseltamivir ranged from ae to ae lm ( table ), indicating that bb ( ae ) and gsb ( ae lm) can be considered resistant against oseltamivir. to confirm these results we investigated the ability of cystus to block virus replication as published before. as a control, virus infected cells were treated with oseltamivir as described earlier. in the absence of the drugs all influenza strains showed similar growth properties (figure , black squares) . first progeny viruses were detectable between and hours post infection (figure , black squares) . treatment with cystus resulted in reduction of virus titers of all influenza virus strains (fig. a-h, open triangles) . surprisingly, oseltamivir failed to inhibit the replication of two h n influenza virus strains (gsb and bb ), supporting the data of ec values ( figure d+h , grey rhombes). we assessed the antiviral activity of cystus against the newly emerged soiv and seven avian h n influenza viruses. cystus showed efficient antiviral activity against the pandemic h n v strain and was effective to a wide range of h n viruses. furthermore, cystus demonstrated a broader and more efficient antiviral potential than oseltamivir. cystus treatment leads to a stronger reduction of progeny virus titers, and more importantly, cystus was effective against all tested viruses, while oseltamivir was unresponsive against two of seven a ⁄ h n viruses. even though the pandemic strain in general is still sensitive to oseltamivir treatment, there are increasing numbers of reports of emerging resistant variants. the treatment with cystus does not result in the emergence of viral drug resistance since the mode of action is an unspecific physical binding of the virus particle that is also beneficial to reduce opportunistic bacterial infections. , , cystus is an extract from a special variety of the plant cistus incanus, and it is very rich in polymeric polyphenols. it is well known that polyphenols exhibit protein-binding capacity. however, cystus exhibited no neuraminidase inhibiting activity. therefore, ingredients of cystus may act in a rather unspecific physical manner by interfering with the viral hemagglutinin at the surface of the virus particle as demonstrated before. while this prevents binding of the virion to cellular receptors, it does not block accessibility and action of the viral neuraminidase. since, infections with influenza a viruses are still a major health burden and the options for control and treatment of the disease are limited, plant extracts such as cystus should be considered as a new candidate drug for a save prophylactic and therapeutic use against influenza viruses. attenuation of respiratory immune responses by antiviral neuraminidase inhibitor treatment and boost of mucosal immunoglobulin a response by co-administration of immuno-modulator clarithromycin in paediatric influenza the antiviral neuraminidase inhibitor osv and zanamivir are widely used treatment options for influenza infection and are being stockpiled in many countries. although mucosal immunity is the frontline of defense against pathogens, the effects of neuraminidase inhibitor treatment on airway mucosal immunity have not been reported. the suppression of viral rna replication and viral antigenic production by these drugs may result in a limited immune response against influenza virus. macrolides, such as cam and azithromycin, have anti-inflammatory and immunomodulatory properties that are separate from their antibacterial effects. [ ] [ ] [ ] this study examined the impact of osv treatment on immune responses in the airway mucosa and plasma in mice infected with iav and pediatric influenza patients. we also assessed the immuno-modulatory effects of cam in influenza patients who were treated with or without osv. female ae -week-old weanling balb ⁄ c mice were nasally inoculated with pfu of iav ⁄ pr ⁄ h n at day . immediately after infection, mice were given lg of osv orally or vehicle at -hours intervals for days. the levels of virus-specific siga in nws and bronchoalveolar fluids (balf) and igg in plasma were measured by elisa as reported previously. a retrospective clinical study was conducted. for the study, children with acute influenza were recruited and grouped according to the treatment received: days treatment with osv (n = ), cam (n = ), osv + cam (n = ), and untreated (n = ). since parents in japan are well aware of the adverse effects of osv especially the neuropsychiatric complications, the decision on whether to administer osv or not and to prescribe cam was made by the parents and the attending paediatricians, based on their anti-viral and immuno-modulatory activity. , comparisons were made of the levels of siga against iav ⁄ h n and iav ⁄ h n , total siga, in nws and disease symptoms before and after treatment. anti-ha siga and total siga in nws of patients were determined from the standard regression curves with human iga of known concentration in a human iga quantitation kit (bethy laboratories). because an affinity purified human anti-ha-specific siga standard of each influenza a subtype is not available, the relative value of anti-haspecific siga amount was expressed as unit (u). one unit was defined as the amount of one lg of human iga detected in the assay system as reported previously. the concentrations of siga in individual nws were normalized by the levels of total siga (lg ⁄ ml). oseltamivir suppresses viral rna replication and viral antigenic protein production. to investigate the influence of daily treatment with osv on ha-specific mucosal and systemic immune responses, we analyzed ha-specific siga levels in nws and balf as well as igg levels in plasma at days and post-infection in mice treated orally with osv or methylcellulose (mc) as vehicle. the osv treated mice showed lower antibody responses in nws and balf than control mice treated with mc solution (table ) . significantly reduced ha-specific siga responses were particularly noted in the osv group at day , the period of maximal mucosal siga induction. the airway secretions and plasma from mice at day did not contain detectable levels of ha-specific antibodies. these findings were supported by other data whereby mice treated with osv displayed significantly lower numbers of ha-specific iga antibody-forming cells (afcs) in the nasal lamina propria, mediastinal lymph nodes, and lungs compared with mc-treated mice. these results clearly indicate that oral administration of osv downregulates ha-specific siga responses in mucosa. on the other hand, there were no significant differences in the elevated levels of ha-specific plasma iga and igg antibodies or the increased numbers of ha-specific iga and igg afcs in the spleen between osv-and mc-treated mice. taken together, these results implicated the oral administration of osv in a suppressed induction of haspecific siga responses in respiratory lymphoid tissues, although systemic ha-specific antibody responses were not significantly affected by osv. since cam up-regulates il- , a mucosal adjuvant cytokine in the airways, and promotes the induction of siga and igg in the airway fluids of mice infected with iav, , we assessed the impact of treatment with osv and ⁄ or cam on the levels of anti-influenza siga in nws and clinical status of influenza patients. the concentration ratio of table . anti-ha-specific siga to total siga in nws was expressed as titer: anti-ha-specific siga (u ⁄ mg) ⁄ total siga (lg ⁄ mg) · . figure shows changes in the anti-ha(h n ) siga ratio (titer) and fold of increase in siga titer in each patient during the -days' treatment for the four different treatment groups. it is noteworthy that, upon admission to the hospital, the siga titers were < in % of patients. during the days of treatment, rapid increases in the titers were observed in almost all patients in cam, osv + cam, and no treatment groups. in contrast, in the osv group, the anti-ha-specific siga titers remained unchanged or decreased in the majority of patients. the finding of significant low induction of anti-viral siga in the osv group was supported by the results of animal experiments. however, the addition of cam to osv augmented siga production and restored mucosal siga levels; % of patients treated with osv + cam showed > -fold increase in the titers during treatment. these observations suggest that cam stimulated the local mucosal immunoresponse in the nasopharyngeal region of patients treated with osv. the prevalence of disease manifestations was also analyzed. among the symptoms listed, a significant decrease in the prevalence of cough was recorded between the no treatment group and the osv + cam group and between the osv group and the osv + cam group (**p < ae ), despite the limited number of patients in each group. the duration of the febrile period was significantly shorter in the osv and osv + cam groups than the no treatment group. however, no significant difference was observed between the osv group and osv + cam group. it has been reported that osv does not affect the cellular immune responses, such as cytotoxic t lymphocytes and natural killer cells. however, the effects of osv on mucosal immunity have not been studied so far. the present study showed that osv treatment of mice infected with iav induced insufficient protective mucosal siga responses in the respiratory tract, although treated mice showed the similar levels of systemic igg and iga antibody responses in plasma to those in mice treated with vehicle (table ) . the observed effect of osv on mucosal immunity was probably due to a suppression of viral replication and viral antigen production in the mucosal layer. these observations in mice are further supported by our clinical reports of siga in nws and balf of osv treated influenza patients. the membered-and membered-ring macrolides have been found to possess a wide range of anti-inflammatory and immuno-modulatory properties, , and to be effective in the treatment of respiratory syncytia and iav infection. , the efficacy of low doses administered on the long term against pathogens that are insensitive to macrolides indicates a mode of action that is separate from their antibacterial activity. , , , in the present study, we evaluated the immunomodulatory effects of cam on mucosal immune responses in pediatric influenza. a decrease in the proportion of total siga that was anti-ha-specific siga during treatment was observed in . % of patients in the osv group (those represented by the dotted lines and closed diamonds in figure ), whereas an increase in the proportion was observed in most patients of the other groups (except for one patient of the untreated group). despite the low or unchanged induction of anti-ha-specific siga in the majority of osv-treated patients, the additional use of cam with osv boosted the mucosal immune response and restored local mucosal siga levels. we are currently engaged in detailed immunological studies of the effects of cam and osv on the levels of mediators controlling iga class switching in nws of influenza patients and airway secretion of mice infected with iav. further studies should clarify the boost mechanisms of cam and the suppression mechanisms of osv in iga class switching. our findings suggest the risk of re-infection in patients showing a low mucosal response following osv treatment and cam effectively boosts the siga production for protection of re-infection. to date there is an urgent need to develop new antivirals against influenza. most of the molecules reported target influenza proteins that acquire rapid mutations of resistance. the development of new molecules that have a broad antiviral activity and are not subjected to influenza mutation is of particular interest. our laboratory and others recently showed that proteases can participate to the innate immune response in the airways through the activation of a family of receptors called par. in particular, through the release of interferon, par agonists curbed viral replication significantly in infected cells. in this study, since erk activation is crucial for virus replication, we investigated whether par could inhibit virus replication through inhibition of the erk pathway. results showed that while influenza a infection alone or par stimulation alone induced erk activation, par stimulation does not inhibit erk activation in influenza infected cells. thus, par agonists may be a potential new drug against influenza viruses that could be used in combination with other anti flu therapy such as the inhibition of the erk pathway. respiratory tract-resident proteases are key players during influenza virus type a infection. , in addition to their direct activating effect on surface viral proteins, lung mucosal proteases can regulate cellular processes by their ability to signal through protease-activated receptors (pars). after cleavage of the receptor by proteases, the new aminoterminal sequence of par binds and activates the receptor internally. these receptors are highly expressed at epithelial surfaces, in particular in the lung, where human influenza virus replicate in vivo. pars are thus directly exposed to proteases present in the airways. among the four different pars, par acts as an antiviral through an interferondependent pathway. , thus, agonists of par are potential new drugs against a broad range of influenza viruses, which is in accordance with the broad antiviral action of interferon. however, the signalling pathway induced by par agonists in influenza a infected cells has still to be investigated. in this manuscript, we showed that influenza infection or activation of par induced erk activation, a crucial step for efficient virus replication. , however, par agonists do not impaired erk activation in influenza a virus infected cells. since the pathway of par protection is likely to be erk-independent, the use of anti erk molecules in combination with par agonists maybe of potential interest in future anti-influenza therapy. influenza viruses a ⁄ wsn ⁄ (h n ) (a kind gift from nadia naffakh) was used in the present study. mdck (madin-darby canine kidney) and the human alveolar type ii a cell were obtained from atcc and grown as previously described. for western blot analysis, the following antibodies were used: monoclonal antibody for phospho-erk ⁄ (t ⁄ y ) and for erk ⁄ antibodies from cell signaling technology (beverly, ma), horseradish peroxydase (hrp)-coupled rabbit polyclonal antibodies against mouse or rabbit igg from paris (compiègne, france). a cells were infected with iav at an moi of in emem medium, as previously described. , at various time points post infection, cells were collected and proteins were analysed as previously described. , par stimulation was performed at °c in emem medium as previously described. after infection and ⁄ or stimulation, cells were lysed in ice-cold lysis buffer. lysates were centrifuged at g for min, and total proteins of the supernatants were analyzed by western blot analysis as previously described. , results since activation of the erk pathway is essential for efficient influenza replication, we first investigated the kinetics of erk activation after influenza infection in human a alveolar epithelial cells. for this purpose, a cells were infected with influenza viruses at a moi of at different time point post-infection, and activation of erk ⁄ pathway was assessed by western blot analysis using an anti-erk antibody. results showed that erk was phosphorylated after influenza infection in a time course depen-dent manner when compared to uninfected cells. in contrast, erk phosphorylation was not observed with heatinactivated viruses, suggesting that productive infection is needed for erk activation ( figure a ). antibodies against erk ⁄ were used as controls. since erk is activated after influenza infection, we then tested whether activation of par in uninfected cells also leads to activation of this pathway. for this purpose, a cells were stimulated with the selective human (h) or mouse (m) par agonist or a control peptide for the indicated time ( figure b ). when exposed to the par agonists and compared to controltreated cells, erk phosphorylation increased over the time course of stimulation. thus, influenza infection or stimulation of par without infection in a cells induced activation of the erk pathway at different time point post-infection. since influenza infection and par stimulation induced erk activation, we then investigated whether par could inhibit erk activation in influenza infected a cells. results in figure showed that in influenza infected cells, par activation for ten minutes does not inhibit erk activation after influenza infection. thus, erk activation is not inhibited by par activation in influenza stimulated cells. in this manuscript, we studied the activation of the erk pathway after par stimulation and or influenza infection. particularly interesting is the fact that either influenza infection or par stimulation alone induce erk phosphorylation in a epithelial cells, while erk activation is not inhibited in a infected cells compared to uninfected ones after par stimulation. proteases are key factor in the pathogenicity of influenza viruses. in addition to the cleavage of ha, necessary for iav replication, extracellular proteases also play a role in the modulation of the immune system against influenza viruses through the activation of pars. particularly par , activated by extracellular trypsin-like proteases, could inhibit virus replication through the release of interferon, , thus, strengthening the immune system via agonist peptides and providing new therapeutic potential against a broad range of influenza strains. in addition, targeting the host instead of the virus could provide a way to escape from virus resistance. thus, a better understanding of how virus escapes from immune surveillance may provide new therapeutic strategies to block iav. in addition, combinations of drugs that block virus replication via different pathways are of interest. the non classical molecules hla-g maybe an interesting new target as we recently showed that it is upregulated after influenza infection, and it is a well known immunotolerant molecule. indeed, it inhibits the innate immune response as well as the adaptive immune response. , also, as previously suggested, the erk signal transduction cascade is also of potential interest since it is crucial for virus replication and particularly influenza replication. , as shown here, it is unlikely that par protection occurs through an erkdependent pathway. thus strengthening the immune response with par agonists and blocking nuclear retention of the viral ribonucleoprotein complexes with inhibitors of the mek ⁄ erk pathway may be alternative combinatory approaches for influenza therapy. in addition, since those potential drugs target the host instead of the virus, this could help in the design of new antivirals molecules more resilient to iav mutations and thus to virus resistance. the initial waves of the first influenza pandemic of the st century have passed. in june , vaccine companies estimated they could produce in months almost . billion doses of pandemic vaccine. instead, they actually produced only million doses, of which % were non adjuvanted preparations. had these doses been produced with adjuvants (i.e., . lg instead of lg ha per dose), an additional billion doses could have been made available. yet there was public opposition to adjuvants in many countries, especially by regulatory officials in the united states. misperceptions about the safety of both adjuvanted and nonadjuvanted vaccines were widespread. added to this, shortfalls in vaccine production, delays in vaccine delivery, and the ''mildness'' of the pandemic itself meant that only a few countries achieved reasonable levels of vaccine coverage. millions of doses went unused and had to be destroyed. supplies of antiviral agents were even more limited. thus, despite the best efforts of influenza scientists, health officials, and companies, more than % of the world's people did not have timely access to affordable supplies of vaccines and antiviral agents. instead, they had to rely on th century public health ''technologies.'' given current understanding of biology in the early st century, they should have had -and probably could have had -something better. this report reviews evidence for an alternative approach to serious and pandemic influenza that could be used in all countries with basic health care systems. instead of confronting the influenza virus with vaccines and antiviral agents, it suggests that we might be able to modify the host response to influenza virus infection by using anti-inflammatory and immunomodulatory agents. this idea was introduced several years ago and has been reviewed in several publications. [ ] [ ] [ ] [ ] [ ] [ ] the central importance of the host response in the pandemic, young adults had high mortality rates. ever since, influenza virologists have sought to answer the question ''why did young adults die?'' by defining the molecular characteristics of the virus that were responsible for its virulence. in doing so, they have overlooked a crucial piece of clinical evidence from the pandemic: compared with young adults, children were infected more frequently with the same virus, yet they seldom died. consequently, the more important question is ''why did children live?'' this can only be explained by recognizing that children must have had a different host response to the influenza virus than adults. physicians have long recognized that for several other medical conditions, both infectious (e.g., pneumococcal bacteremia) and non-infectious (e.g., multiple trauma), children have a more benign clinical course than adults. , a corollary of this observation is that secondary bacterial pneumonia, although commonly found in young adults in , could not have been the primary cause of death. children must have had the same or higher rates of nasopharyngeal colonization with the same bacteria that were associated with pneumonia deaths in adults, yet children seldom died of secondary bacterial pneumonia. if young adults died with secondary bacterial pneumonia, underlying host factors must have made them more susceptible. few people who die of influenza do so during the first few days of illness when pro-inflammatory cytokine levels are high. instead, like patients with sepsis, they usually die in the second week, when anti-inflammatory cytokines and immunosuppression dominate. , , influenza deaths occur more frequently in older persons with cardiopulmonary conditions, diabetes, and renal disease, but as seen in the h n pandemic, they also occur in younger adults with obesity, asthma, and in women who are pregnant. regardless of age, people with all of these conditions share one characteristic in common: they have chronic low-grade inflammation. in effect, their ''innate immune rheostats'' have been set at different, and perhaps more precarious, levels that make them more vulnerable to influenza-related complications. laboratory studies of influenza virus infection confirm the importance of the host response. in several studies in mice in which the host response has been modified (e.g., cytokine knockout), survival has been improved without increasing virus replication in the lung. in fact, severe disease can be induced without any influenza virus replication. for example, fatal acute lung injury has been induced in mice by inactivated (not live) h n virus. in this model, antiviral agents would be useless; only the host response could be responsible for disease. these observations raise the following question: could the host response be modified so patients with severe seasonal and pandemic influenza might have a better chance of surviving? influenza is associated with acute coronary syndromes, and influenza vaccination and statins reduce their occurrence. these associations led to the suggestion in that statins might be used to treat pandemic influenza. other agents that might also be effective include ppara and pparc agonists (fibrates and glitazones, respectively) and ampk agonists (e.g., metformin). , these agents have been studied in laboratory models of inflammation, sepsis, acute lung injury, ischemia ⁄ reperfusion injury, energy metabolism, mitochondrial function, and programmed cell death. the results of these studies cannot be reviewed in detail here, but the major findings for cell signaling are summarized in the table . unfortunately, the results of experimental studies are not always clear cut. for example, in one study of influenza virus infected mice, il- was necessary for containing infection, but in another study il- appeared to be harmful. nonetheless, overall understand-ing of cell signaling pathways in influenza virus infections and the actions of statins, glitazones, fibrates, and ampk agonists strongly suggest that these agents could benefit patients with severe influenza. laboratory studies in mice infected with pr (h n ) h n and pandemic h n viruses show that resveratrol, fibrates, glitazones, and ampk agonists reduce mortality by - %, often when treatment is started - days following infection. - (resveratrol is a polyphenol found in red wine. it shares with these other agents many of the same cell signaling effects.) in h n -infected mice, treatment with celecoxib and mesalazine, together with zanamivir, showed better protection than zanamivir alone. remarkably, these immunomodulatory agents have not increased virus replication. even more remarkable, in another model of a highly inflammatory and frequently fatal conditionhepatic ischemia ⁄ reperfusion injury -glitazone treatment ''rolled back'' the host response of ''young adult'' mice ( - weeks old) to that of ''children'' ( - weeks old). this unique study suggests that immunomodulatory treatment might roll back the damaging and sometimes fatal host response of young adults with influenza to the more benign and rarely fatal response of children. several, but not all, observational studies have shown that outpatient statins decrease hospital admissions and mortality due to community-acquired pneumonia. for influenza itself, preliminary evidence presented in october suggests that immunomodulatory treatment of influ- table . cell signaling targets that might be affected by immunomodulatory treatment of severe seasonal and pandemic influenza* down regulate pro-inflammatory cytokines (e.g., nf-kappab, tnfa, il- , il- ) up regulate anti-inflammatory cytokines (il- , tgfb) up regulate pro-resolution factors (lipoxin a , resolvin e ) up regulate ho- and decrease tlr signaling by pamps and damps up regulate enos, downregulate inos, restore inos ⁄ enos balance and stabilize cardiovascular function decrease formation of reactive oxygen species and decrease oxidative stress improve mitochondrial function and restore mitochondrial biogenesis decrease tissue factor and its associated pro-thrombotic state stabilize the actin cytoskeleton in endothelial cells and intracellular adherins junctions, and thereby increase pulmonary barrier integrity and decrease vascular leak differentially modify caspase activation and apoptosis in epithelial and endothelial cells, macrophages, neutrophils and lymphocytes in the lung and other organs increase the bcl- ⁄ bax ratio in influenza virus-infected cells and prevent the apoptosis necessary for virus replication. *see references , , , for details. nf-kappab, nuclear factor kappab; tnfa, tumor necrosis factor alpha; tgfb, transforming growth factor beta; ho- , heme oxygenase - ; tlr, toll-like receptor; pamp, pathogen-associated molecular pattern; damp, damage associated molecular pattern; enos, endothelial nitric oxide synthase; inos, inducible nitric oxide synthase. enza patients with severe illness could be beneficial. in a study of almost patients hospitalized with laboratoryconfirmed seasonal influenza, inpatient statin treatment reduced hospital mortality by %. in these patients, the cell signaling effects of statin treatment, summarized in the table , probably acted to reduce pulmonary infiltrates, maintain oxygenation, stabilize myocardial contractility and the peripheral circulation, reverse immunosuppression, restore mitochondrial biogenesis, and prevent multi-organ failure. achieving these clinical effects led to a decrease in mortality. because of the molecular cross-talk between statins, fibrates, glitazones, and ampk agonists, , similar clinical benefits might be expected from other members of this ''family'' of immunomodulatory agents. simvastatin, pioglitazone, and metformin are produced as inexpensive generics in developing countries. they are used throughout the world in the daily treatment of millions of patients with cardiovascular diseases and diabetes. global supplies are huge. because most people with influenza recover without specific treatment (this was true in ), not all patients would require immunomodulatory agents. instead, only those at risk of ards, multi-organ failure, and death would need to be treated. importantly, the cost of treatment for an individual patient would be less than $ . (d.s. fedson, unpublished observations). moreover, unlike vaccines they could be used on the first pandemic day. thus far, influenza scientists and the institutions that support their work (e.g., nih and cdc, national health agencies in many countries, the bill and melinda gates foundation, the welcome trust, and the world health organization) have shown little interest in immunomodulatory treatment. nonetheless, when more than % of the world's people have no access to influenza vaccines and antiviral agents, their physicians must have access to an effective ''option,'' especially one that might be lifesaving. research on immunomodulatory agents for influenza must involve investigators in many fields outside influenza science -those with expertise in the molecular and cell biology of inflammation, immunity, sepsis, cardiopulmonary diseases, endocrinology and metabolism, ischemia ⁄ reperfusion injury, mitochondrial function, and cell death. laboratory studies needed to identify promising treatment agents would probably cost $ - million (d.s. the results of these studies would inform clinical trials that critical care physicians are already eager to undertake. , this work will be especially important for people in developing countries where critical care capacity is extremely limited and not likely to improve. like critical care physicians, influenza scientists too must recognize that they cannot afford not to undertake research to determine whether generic immunomodulatory agents might be useful in managing severe seasonal and pandemic influenza. the nf-kappab-inhibitor sc efficiently blocks h n influenza virus propagation in vitro and in vivo without the tendency to induce resistant virus variants introduction influenza is still one of the major plagues worldwide. the appearance of highly pathogenic avian influenza (hpai) h n viruses in humans and the emergence of resistant h n variants against neuraminidase inhibitors highlight the need for new and amply available antiviral drugs. we and others have demonstrated that influenza virus misuses the cellular ikk ⁄ nf-kappab signalling pathway for efficient replication, suggesting that this module may be a suitable target for antiviral intervention. here, we show that the novel nf-kappab inhibitor sc efficiently blocks replication of influenza a viruses, including avian and human a ⁄ h n isolates in vitro in concentrations that do not affect cell viability or metabolism. in a mouse infection model with hpai a ⁄ h n and a ⁄ h n viruses, we were able to demonstrate reduced clinical symptoms and survival of sc treated mice. moreover, influenza virus was reduced in the lung of drug-treated animals. besides this direct antiviral effect, the drug also suppresses h n -induced overproduction of cytokines and chemokines in the lung, suggesting that it might prevent hypercytokinemia we hypothesise to be associated with pathogenesis after infections with highly pathogenic influenza viruses, such as the a ⁄ h n strains. thus, a sc -based drug may serve as a broadly active nontoxic anti-influenza agent. to assess the number of infectious particles (plaque titers) in organs a plaque assay using avicel Ò was performed in -well plates as described by mastrosovich and colleagues. virus-infected cells were immunostained by incubating for hour with a monoclonal antibody specific for the influenza a virus nucleoprotein (serotec) followed by minutes incubation with peroxidase-labeled anti-mouse antibody (dianova) and minutes incubation with true blueÔ peroxidase substrate (kpl). stained plates were scanned on a flat bed scanner and the data were acquired using microsoft Ò paint software. the virus titer is given as the logarithm to the basis of the mean value. the detection limit for this test was < ae log pfu ⁄ ml. organs of infected and control mice were homogenized and incubated over night in ml trizol Ò reagent (invitrogen) at °c. total rna isolation was performed as specified by the manufacturer (invitrogen). rna was solubilised in ll rnase free water and diluted to a working concentration of ng rna ⁄ ll. reverse transcription real-time pcr was performed using quantifastÔ sybr Ò green rt-pcr kit and quantitect primer assays (qiagen) . all samples were normalized to gapdh and fold expression analyzed relative to uninfected controls. ct values were obtained with the smartcycler Ò (cepheid). to answer the question whether the nf-kappab inhibitor sc shows antiviral properties against influenza virus, h n infected mdck cells were treated with different concentrations of the inhibitor (figure ). already treatment with nm of sc led to a reduction of viral cpe of more than %. almost % protection of cells was achieved when cells were treated with lm sc . the results indicated that sc has antiviral properties at concentrations ranging from to nm. we next tested whether sc would also be effective in the mouse model of influenza virus infection. when h n mice were treated i.v. once daily for days with mg ⁄ kg sc , survival rate of the animals increased significantly (p < ae ). the same results were found when h n influenza virus infected mice were treated i.p. with mg ⁄ kg sc (data not shown). moreover, sc treatment was not only effective when the inhibitor was given prior to h n influenza virus infection, but also in a therapeutic setup when sc was applied to the animals days after infection (data not shown). since influenza virus infected mice showed increased survival after lethal infection, we next questioned whether the amount of influenza virus was reduced in the lung. therefore, we performed quantitative real-time (qrt) pcr to detect viral mrna. mice were treated with either sc or the solvent, and hour later the lungs were prepared to perform qrt-pcr. as shown in figure a the amount of viral mrna was reduced by % in sc treated mice compared to solvent treated controls, indicating that sc leads to a reduced expression of h n specific mrna in the lung of infected mice. since infection of mice with h n leads to hypercytekinemia, we also investigated the expression of cytokines in sc treated mice. as shown in figure b the amount of il- specific mrna was drastically reduced in sc treated mice compared to solvent treated controls. moreover, also the expression of ip- was altered in sc treated h n influenza virus infected mice. here, roughly % reduction of specific mrna was detectable ( figure c ). thus, sc leads to a reduced transcription of il- and ip- in h n infected mice. there is an urgent need for new concepts to develop antiviral drugs against influenza virus. targeting cellular factors is a promising but challenging approach, and the concerns about side effects are obvious. however, it should be considered that drugs targeting viral factors, such as amantadine or oseltamivir, also exhibit a wide range of side effects in patients. thus, drug safety has to be rigorously tested in clinical trials regardless whether a drug targets a cellular or a viral factor. moreover, resistance against human h n influenza viruses and highly pathogenic avian h n virus strains to oseltamivir and amantadine have been reported. in that respect, the strategy to target cellular factors , might be one way to ensure that new drugs against influenza virus will be useful and effective for a long time without causing the development of resistant virus variants. we were able to demonstrate that the nfkappab inhibitor sc is able to reduce influenza virus activity in cell culture. moreover, the compound was also effective against highly pathogenic avian influenza viruses of the h n and h n subtypes in the mouse model. next to the reduction of virus sc was also able to reduce h n -induced overproduction of cytokines and chemokines in the lung in the lung of mice after infection with h n . most importantly, the drug did not show any tendency to induce resistant virus variants (data not shown). thus, a sc based drug may serve as a broadly active non-toxic antiinfluenza agent. [ ] [ ] [ ] [ ] [ ] in hong kong, the first confirmed case was a tourist from mexico reported on may , . the local government made its first attempt to contain the spread of h n in the local community by closing the metropark hotel where that tourist was staying, and quarantining guests and staff for days. following identification of the first local case around weeks later on june , , the government closed all kindergartens and primary schools from june until early july. fever clinics were also opened, the alarm levels in hospitals were raised to the highest, and a public education campaign was implemented. previous studies of the community responses to severe acute respiratory syndrome (sars) and human-to-human h n avian flu identified the importance of understanding the background perceptions of risk and psychological impact on the community. [ ] [ ] [ ] [ ] [ ] in this study we investigated the psychological and behavioral responses of the general local community throughout the first wave of ph n , and we also examined the factors associated with greater use of preventive measures. a total of surveys were conducted between april and november , covering the entire first wave of the ph n pandemic. computer generated random-household telephone numbers from all land-based local telephone numbers covering over % of hong kong households were used to recruit a total of local adults. one cantonese-speaking adult (age ‡ ) was invited for interview in each selected household on the basis of a kish grid. the survey instrument was based on previous experience in sars and avian influenza projects. information, including knowledge on modes of transmission, psychological responses to pandemic influenza, preventive behaviors, attitudes towards the new vaccines and socio-demographics, was collected. informed consent was obtained prior to the interview. ethics approval was obtained from the institutional review board of the university of hong kong. descriptive statistics were weighted by sex and age based on the reference population data provided by the hong kong government census and statistics department. multivariable logistic regression analyses were used to examine the association between the use of preventive measures and knowledge, perceptions and behaviors, sociodemographic characteristics, and psychological responses to pandemic influenza. multiple imputation was used to cope with a small proportion of missing data and make the best use of all available data. statistical analyses were conducted in r version . . (r development core team, vienna, austria). twelve thousand and nine hundred and sixty-five local adults were recruited throughout the study period, with a total of telephone calls being made; the response rate among eligible participants was . %. hong kong entered the containment phase after the world health organization (who) announced a global alert, and policies including border screening, tracing, and quarantine of doi: . /j. - . . .x www.influenzajournal.com suspected cases were implemented. hong kong transitioned to the mitigation phase on june , when the first local case was reported. the chronology of these and other events plus the epidemic curve of laboratory-confirmed ph n cases are shown in figure (a) . the anxiety scores and risk perception of the respondents are shown in figure (b,c) . anxiety, measured by the state trait anxiety inventory, remained steady throughout the study period. in response to the announcement made by who and the unknown nature of the new virus, a higher proportion of the respondents expressed worry (more, much more, or extremely more worried than normal) if developed ili and perceived ph n severity (same, more, or much more serious than sars) initially in early may . fewer respondents reported worry if they developed ili as the pandemic proceeded, with a slight perturbation around the first deaths in july and a steady decline to . %, while perceived severity of ph n declined more dramatically after an early high. perceived risks of infection of respondents (absolute susceptibility) and risk relative to others (relative susceptibility) were also investigated and found to remain relatively stable throughout the first wave, with no indication of an increase during the period of peak ph n activity in september (figure c) . as the first wave of ph n progressed, knowledge on modes of transmission did not improve. on the contrary, later in the epidemic increasing proportions of respondents reported oral-fecal and cold weather as modes of transmission of ph n . around - % of the respondents did not recognize direct and indirect contact or touching infected persons and contaminated objects as transmission routes for ph n throughout the first wave ( figure d ). higher proportions of respondents avoided crowded places and rescheduled travel plans in the second half of june when local kindergartens and primary schools were closed and the first ph n -associated deaths were announced. social distancing measures such as avoiding crowded places and rescheduling travel plans remained stable with slightly decreasing trends thereafter. the use of hygiene measures and other social distancing strategies was relatively stable with slightly decreasing trends during the study period ( figure ). female sex and older age were generally associated with greater reported use of hand hygiene measures, home disinfection, avoidance of crowded places, and rescheduling of travel plans. female sex was also positively correlated with use of face masks and cough etiquette. we found a negative correlation between anxiety and use of all hand hygiene measures and cough etiquette, but a positive correlation between anxiety and use of home disinfection and (c) proportion of the respondents reporting higher worry if developed flu-like symptoms (more, much more, or extremely worried), higher perceived seriousness of h n compared to sars (much more or more severe), higher probability to contract h n over the next month (certain, much more, or more likely), higher probability to contract h n over the next month compared to others outside family (certain, much more, or more likely). (d) proportion of the respondents identifying possible modes of transmission as the actual modes of transmission of h n . social distancing measures. other significant factors contributing to greater use of preventive measures were worry and knowledge. greater worry was associated with higher probability of home disinfection, social distancing measures, and use of face masks. knowledge that h n could be spread by indirect contact was associated all the investigated preventive measures, and knowledge that h n could be spread by droplets was associated with cough etiquette, but not face masks. there were no consistent trends between all the investigated preventive measures and absolute and relative susceptibility. community transmission emerged in hong kong in mid-june , and prior to emergence of community transmission, perceived risk and perceived severity were high. as ph n spread in hong kong, risk perception declined, even at the same time as incidence was increasing. anxiety was low throughout, at around . on the -point scale, compared to a maximum of . during sars on the same scale. anxiety has been showed to be positively correlated to personal hygiene measures and social distancing in previous studies; , however, we found a negative correlation between anxiety and use of all hand hygiene measures, cough etiquette, and face masks, and a positive correlation between anxiety and home disinfection. the differences in findings may be due to the fact that our anxiety measure was not specific to h n , and the score could be affected by other factors including economics. unlike hygiene measures, higher anxiety level, greater worry, and higher risk of perception were all associated with more social distancing. , , , social distancing is the most direct strategy in avoiding infection from other people, and it is commonly observed in an outbreak that the general public avoids crowded places, travelling to other countries, and social gatherings, , but the economic impact could be substantial. as community incidence of h n peaked, we did not observe any increase in use of preventive measures (figure ) . we found that face mask use peaked at the early stage of the pandemic, while hand hygiene remained fairly constant, and the knowledge on the modes of transmission of ph n did not improve over time. the lack of substantial change in preventive measures or knowledge about the modes of ph n transmission in the general population suggests that community mitigation measures played little role in mitigating the impact of ph n in hong kong. on the other hand, knowledge that ph n could be spread by indirect contact was associated with all of the preventive measures studied. consistent with reports during the sars period, , this study also showed that females and those of older age were more likely than others to use hygiene measures, avoid crowded places, and reschedule travel plans. this study has some limitations. first, this was a crosssectional study that was carried out at different time points, rather than a longitudinal study following the same individuals over time, and so the inferences on changes in behavior may need to be interpreted more cautiously. second, we recruited samples from all land-based local telephone numbers that cover % of hong kong households, but the response rate was not high enough to guarantee a representative sample, and this could be a source of selection bias. third, the responses were self-reported, and this may lead to social desirability bias in estimating knowledge, attitudes, and preventive behaviors. fourth, since the hong kong population has previously gone through unique experiences from sars in and avian flu in , our results may not be comparable to other countries or settings. in conclusion, this study revealed that the ph n pandemic failed to generate an increase use of preventive measures in the local community. there was no association between anxiety level and the events of the pandemic. with a relatively low mortality and morbidity rates compared to sars, ph n was not a matter of concern in the hong kong community. the lack of substantial change in the use of preventive measures and improvement in knowledge on the modes of transmission of ph n suggested that public health campaigns during the pandemic may not have had substantial effects on the general public. london is a major tourist destination, the seat of government and finance in the uk, and in will host much of the olympic and paralympic games. along with the rest of the global community, in and early london faced the challenges of responding to the first pandemic of the st century. at the time, nhs in london was composed of organisations, including the london ambulance service, acute hospitals, mental health and primary care trusts, and the strategic health authority. while london's nhs is well practiced at responding to large, big bang incidents, the influenza a ⁄ h n v pandemic was a rising tide event that lasted many months. significant preparatory work had been undertaken prior to april , which meant that the nhs in london was ready to respond. nhs london (the strategic health authority for london) led the response in partnership with local managers in all nhs organisations. the first uk cases of influenza a ⁄ h n v were reported in scotland on april, with the first in london on april. cases continued to increase, and the first wave peaked in london in july. cases reduced over the school summer holidays, but increased again when children returned to school at the start of september, and a second, smaller wave occurred. it is essential that the nhs learns from the ⁄ influenza a ⁄ h n v pandemic to ensure it is prepared for future challenges. nhs london provided a standardised debriefing pack to all nhs organisations in the region to identify, capture, and learn lessons. each debrief event involved health and inter-agency partners to ensure all viewpoints were considered and brought together in a single local report. all local reports were compiled in an over-arching document, which brings together common themes to inform ongoing preparedness in the region. the debrief process identified a number of common themes, such as the need for clear and appropriate communication, the importance of working with partners, and the benefits of strong and early leadership. however, differences between and within organisations were also highlighted; for example, some wanted more freedom for local decision making, whereas others would have preferred more stringently applied central direction. the following paragraphs considers individual areas assessed in the debrief process. command and control was in the main effective, with clear direction delivered from the national centre through nhs london to local nhs organisations. effective leadership is essential; the identification of senior local individuals to lead the response with teams of people to support them was critical. appropriate use of technology to communicate messages and coordinate command and control processes greatly aided the response. this included the development of the nhs london noon brief, a daily digest and associated web portal, and regular teleconferencing. key points are: • operational management at all levels must be considered in pandemic planning. • appointing an executive lead in each organisation was invaluable in the response. • pandemic flu planning for london must continue to be regionally led. communication is an essential component of the response to any incident. it must be clear, timely, and accurate. in the main, communication was excellent and met these criteria. one of the most challenging aspects was when messages from partner organisations differed, which occasionally led to confusion, unnecessary work, or frustration. the use of technology greatly aided communication across the region and supported the response; this included secure web sites, bluetooth, and text messaging etc. key points are: • regular internal communications and staff briefings are critical in the response to emergencies. • regular teleconferencing should be incorporated into future plans. • organisations should consider proactive and innovative methods for communicating during emergencies. robust partnership working was an essential component of pandemic preparedness work; however in the event, the a ⁄ h n v pandemic had little impact on sectors in london other than health. resilient communication networks between organisations, a common understanding, and the ability to make decisions were essential to the response at local level. ipcs proved an excellent mechanism to maintain local working relationships and resolve problems. clarity on the seniority of those attending these meetings and whether multi-site organisations such as mental health trusts should attend every ipc should be considered on a local and regional basis. key points are: • pandemic planning must remain part of inter-agency working. • social care resilience and planning must be embedded and integrated in health planning. 'vulnerable groups' is a universal term that covers a large and fluid group of individuals with different needs. ensuring access to healthcare during the pandemic for those who became vulnerable due to the situation, or those identified as such prior to the event, was the role of the pct in partnership with the local authorities. work continues to ensure that communication with vulnerable people is appropriate and timely in all incidents, and that organisations work together to achieve this. key points are: • planning to support the breadth of vulnerable people must continue. • pandemic preparedness for the prison sector should be further developed. • red ⁄ amber ⁄ green ratings for assessing vulnerabilities of mental health service users in an emergency should be further developed across the region. correct and appropriate usage of ppe is an essential component of reducing influenza spread, particularly in healthcare settings. london's nhs had been working towards developing local stockpiles of ppe when the pandemic commenced; however, there was little in place. the unanticipated national stockpile, while providing ppe to all organisations, was accompanied with some challenges in that it was often unfamiliar stock. key points are: • work around local stockpiling of non-standard consumables should continue. • regular training and fit testing of respirators should be embedded in all organisations. antiviral treatment was a core component of the response to influenza a ⁄ h n v, and was provided free of charge from a national stockpile. npfs reduced pressure on frontline nhs services once it was activated; however, there were concerns that patients could 'cheat' the system and obtain the drugs prior their clinical need. information about storage requirements of countermeasures must be clearly explained when they are delivered to frontline services, and the potential for recall into national stockpiles should be planned for. key points are: • regular exercising of local mass countermeasures centres and antiviral collection points (acps) should continue. • the use of community pharmacies as acps should be further considered in the capital. pandemic influenza vaccine uptake by healthcare workers was better than usual seasonal influenza uptake in the majority of nhs organisations, but could have been even better. this was largely due to the second pandemic wave not being as significant as expected, lack of clarity around when the vaccine would be delivered, and limited amounts being available initially. • gp-led and mass vaccination models for pandemic vaccination should be considered in local plans. • local lessons from the pandemic vaccination campaign should be applied to seasonal flu vaccination. the ability to maintain or increase capacity in response to a surge in demand, no matter what the cause, must be planned for. any of a number of situations could result in reduced staff or more patients, such as industrial action, transport disruption, disease outbreak, major incident, or poor weather. the work undertaken during planning for and responding to the pandemic will stand organisations in good stead for future disruptions. the importance of robust business continuity planning locally cannot be overlooked, as this is a key component of maintaining and increasing capacity. key points are: • local gp 'buddy schemes' should be encouraged for response to extreme pressure events. • organisations should regularly run staff skills audits so as to be aware of their overall capability for managing emergencies. • less emphasis should be placed on the use of retired staff when planning service continuity. reporting is a necessary but onerous task, and is often one of the most time-demanding parts of any incident response. it is also the aspect least likely to be tested through exercising. nhs london worked with organisations to endeavour to reduce reporting pressures, but much of this was dictated by central government. it is essential that future reporting requirements are proportional, informative, and realistic. while recognising it is not possible to predict the detail of information that may be requested, some broad assumptions can be made. key points are: • organisations should consider how they would collect and collate data from disparate parts of their organisation, rather than focussing on the detail of what that might be. • national and regional planning should consider the need for information and how this is balanced with the demand this places on organisations. • the introduction of the concept of a daily dashboard to identify areas of pressure should be incorporated into pandemic flu planning. the winter and pandemic influenza resilience assurance process undertaken in autumn was a useful process to inform planning for the first winter when the pandemic virus would be circulating in the uk. this consisted of a regional inter-agency exercise and a comprehensive review of the winter and pandemic plans of all nhs organisations in london. • regular assurance of pandemic flu preparedness should be maintained. • future resilience assurance processes should be undertaken in a timely and measured manner. • local organisations should continue to undertake regular pandemic flu exercises. the recovery period is as important as the response, but often receives minimal attention and has the potential to suffer as staff return to their normal jobs. one of the aspects that was not anticipated during the pandemic was the amount of stock (ppe, antivirals, and vaccine consumables) that would be recalled into national stockpiles. this proved particularly challenging for pcts who had to coordinate the process across their local areas. key points are: • the recovery period of an emergency must be given the same status and importance as the response. • future pandemic flu planning must include the recovery of national stockpiles of equipment and medicines. it is essential the lessons from the ⁄ influenza a ⁄ h n v pandemic are learnt and embedded into business-as-usual and emergency response processes in preparation for the next pandemic and other incidents. even though the a ⁄ h n v pandemic was generally milder than previous pandemics, it still presented challenges to the nhs in london. the biggest challenge that remains is to ensure that the public and nhs staff are aware that a more virulent virus could cause significantly more illness, death, and disruption, and that we must maintain our preparedness should this happen. the influenza a ⁄ h n v pandemic has been a major stimulus to business continuity planning and emergency preparedness across health in london, and many of the experiences during the pandemic proved invaluable in the unusually severe weather in early . it is important that this impetus and focus is maintained. changes to the nhs landscape in london will be considered in ongoing pandemic and emergency preparedness to ensure we remain as well prepared as possible for future events, particularly as london approaches the olympic and paralympic games. one of the major lessons learnt from all global pandemic events is that better preparedness of national health systems to deal with influenza viruses could make a significant difference. the way national health systems operate during inter-pandemic and the pandemic alert periods and the methods they use to address potential threats posed by zoonotic viruses with pandemic potential, as well as sea-sonal influenza epidemics, can clearly indicate whether the countries have enough capacities to respond adequately to unexpected influenza outbreaks. these public health decisions to ensure the maximum of efficiency require a robust scientific knowledge base. the who public health research agenda for influenza developed by the global influenza programme (gip) in cooperation with international influenza experts identified specific research topics and their importance in meeting stream-specific breakout discussion groups during the global consultation meeting included representatives of researchers and public health professionals. funding organizations were invited to observe the process with no direct participation in the deliberations. the methods used to design the research roadmap for an influenza pandemic scenario are closely related to the process of development of the final document of who public health research agenda for influenza. during a pandemic scenario, the group prioritized topics and questions relating to rapid action and response. five to key public health needs associated with a pandemic scenario have been identified for each of the research agenda streams: five priority public health topics were identified for a pandemic scenario as follows: • examination of host range and transmission dynamics of animal influenza viruses to guide surveillance, control strategies, and risk communication. • enhanced surveillance in animals and humans to monitor virus evolution: o early detection of novel reassortants or changes in genotype and ⁄ or phenotype related to virulence. o development of epidemiological and laboratory diagnostic tools and capacity building to optimize case finding. o develop a framework for surveillance in animals that address ethical, legal, and social barriers to intra-pandemic surveillance and reporting. • deconstruct the origins of the pandemic virus to identify factors that permitted efficient human transmission. • develop strategies to limit economic, social, and cultural disincentives of animal-based interventions to reduce intra-and inter-species transmission. • operational research to optimize risk communication in the early phases of the pandemic linked to animal husbandry and food safety. stream : limiting the spread of pandemic, zoonotic and seasonal epidemic influenza ten priority research topics were identified for both pandemic and inter-pandemic scenario as follows: transmissibility of influenza across the progression of infection and spectrum of disease: • relative contributions of the different modes of transmission for influenza. five priority public health topics were identified for a pandemic scenario as follows: • identification of groups at higher risk of infection and severe disease outcome through enhanced surveillance. • understanding disease severity and identification of predictors of severe outcomes. • investigation of vaccine effectiveness, especially in high risk groups in diverse geographic areas. • establishment ⁄ enhancement of pharmacovigilance, particularly for adverse events among at-risk groups. • optimization of strategies for rapid and targeted vaccine deployment. • rapid assessment to optimize acceptance of pandemic vaccine. six priority public health topics were identified for a pandemic scenario as follows: • collaboration and coordinated sharing of data, protocols, regulatory, and other implementation strategies and databases from different countries on all aspects of patient management and outcome to accelerate improvements in patient care. • development of best practices in patient management in different settings, including checklists and algorithms for clinical care and treatment, prognostic parameters, and tests to predict potential for the development of severe disease. • rapid, reliable, simple, low-cost point-of-care diagnostic tools for influenza. • best use of current antiviral drugs and optimal formulations in different target populations, such as parenteral and other routes of administration for severe infections. • use of combination therapies, including use of adjunctive therapies (e.g., use of convalescent serum and immunomodulators). • role of ongoing viral replication, host responses, and the effect of co-infections in the pathogenesis of severe disease. modern tools for early detection and monitoring of disease the group on surveillance tools concluded that the agreed topics of interest were equally applicable during a pandemic or inter-pandemic period: • studies to appraise and adapt modern technologies for early detection of influenza outbreaks in surveillance at the human-animal interface. • develop, integrate, and evaluate innovative approaches for influenza surveillance and monitoring with other existing disease monitoring systems. • study efficient mechanisms on sharing data, clinical specimens, and viruses with consideration for local, ethical, legal, and research perspectives. • examine the timeliness and quality of data required for early detection from local to national and global levels for the respective stakeholders. five priority public health topics were identified for a pandemic scenario as follows: • identify environmental determinants of seasonal variation in influenza transmissibility in tropical and temperate regions. • estimate the transmission risk associated with types of contacts by comparing measured contact patterns with outbreak data. • incorporation of validated models of behavioral responses to risk and control measures in virus transmission. • development and implementation of novel technology for real-time sero-surveillance during a pandemic. • develop experimental and theoretical framework to assess host adaptation to study host receptor, antigenicity, and virulence. modern tools for strategic communication three priority public health topics were identified for a pandemic scenario as follows: • evaluate tools to more rapidly and accurately assess and monitor knowledge, attitudes, beliefs, and practices in different population groups to guide future communication efforts; develop tools and methods to more rapidly and accurately assess and monitor knowledge, attitudes, beliefs, and practices in different population groups, and thereby, guide future communication efforts. for communicating in different cultural settings, which engage and empower individuals and communities to practice and promote appropriate risk reduction measures. implementation of the identified research priorities is expected to underpin public health decision making at all levels with proven knowledge that will help to save large numbers of lives, reduce health costs and economic loss, and mitigate potential social disruption. complemented by an analogous research roadmap for a pandemic influenza scenario, the research recommendations for an interpandemic period represent a framework to provide evidence to guide public health policies on influenza control. one of the major lessons learnt from all global pandemic events is that better preparedness of national health systems to deal with influenza viruses could make a significant difference. these public health decisions to ensure the maximum of efficiency require a robust scientific knowledge base. the who public health research agenda for influenza developed by the global influenza programme (gip) in cooperation with international influenza experts identified specific research topics and their importance in meeting public health needs for inter-pandemic periods according to its five key research streams: • stream . reducing the risk of emergence of pandemic influenza. • stream . limiting the spread of pandemic, zoonotic, and seasonal epidemic influenza. • stream . minimizing the impact of pandemic, zoonotic, and seasonal epidemic influenza. • stream . optimizing the treatment of patients. • stream . promoting the development and application of modern public health tools. stream-specific breakout discussion groups during the global consultation meeting included representatives of researchers and public health professionals. funding organizations were invited to observe the process with no direct participation in the deliberations. the methods used to design the research roadmap for an influenza inter-pandemic scenario are closely related to the process of development of the final document of who public health research agenda for influenza. during an inter-pandemic phase, a more comprehensive approach was applied to establish research topics and prioritizing a range of questions that will build a solid foundation to guide research activities to support public health decision making. five to ten key public health needs associated with an inter-pandemic scenario have been identified for each of the research agenda streams: stream : limiting the spread of pandemic, zoonotic, and seasonal epidemic influenza ten priority research topics were identified for both pandemic and inter-pandemic scenario as follows: . transmissibility of influenza across the progression of infection and spectrum of disease . relative contributions of the different modes of transmission for influenza . biological, behavioral, and social host factors that influence the risk of transmission and infection . patterns, drivers, and mechanisms affecting the seasonality of transmission . viral and population factors that influence transmission and spread of different influenza types, subtypes, and strains . strategies to reduce the transmission of influenza in community, household, and health care settings, especially in less-resourced areas . impact and cost effectiveness of social measures, such as school closures, and the role of surveillance in assessing timing of these interventions . impact, effectiveness, and cost effectiveness of individual measures, such as isolation and quarantine . role of vaccination in limiting the spread of influenza and strategies for its use . impact of antiviral treatment and prophylaxis in reducing transmission of influenza stream : minimizing the impact of pandemic, zoonotic, and seasonal epidemic influenza . identify higher risk groups and severe disease through surveillance; disease severity and identification of predictors of severe outcomes . evaluate vaccination preventable disease burden and the potential impact of immunization programs through vaccine demonstration projects . enhancement of the properties of existing vaccines, including duration and breadth of protection, safety, immunogenicity, and dosesparing . development of new vaccines and vaccine platforms, especially suitable for under-resourced country settings . study the effectiveness of vaccine strategies to reduce disease burden in children and other high risk groups in a wide range of settings . improved uptake and acceptability of vaccines for both seasonal and pandemic influenza seven priority public health topics were identified for an inter-pandemic seasonal influenza scenario as follows: inter-pandemic seasonal influenza scenario . research on the burden of severe disease with a focus on regionalspecific factors, such as the burden of tb and hiv and optimization of pandemic and management . development of new antiviral strategies and validation of surrogate endpoints which may aid in advancing understanding of disease progression . further clinical evaluation of current antiviral drugs, particularly in populations at risk . integration of seasonal influenza with pandemic preparedness; strengthen surveillance, health care systems, capacity, and preparedness planning . improving diagnostics (e.g., multiplex assays for viruses and bacteria), including antiviral resistance testing at point-of-care . dissemination of best practices, situation analysis, preparation for next epidemic (e.g., establish protocols for rotating stockpiles of antiviral drugs) . increased attention to basic science research such as studying immunomodulatory drugs five priority public health topics were identified for an inter-pandemic zoonotic influenza scenario as follows: inter-pandemic zoonotic influenza . antiviral susceptibility of circulating zoonotic viruses (e.g., h , h , h influenza viruses) . reassortment between zoonotic and human influenza viruses and the potential for inter sub-type spread of antiviral resistance and virulence modern tools for early detection and monitoring of disease the group focusing on surveillance tools concluded that the agreed topics of interest were equally applicable during both pandemic and inter-pandemic period: . identify modern technologies for early detection of influenza outbreaks as well as their application in surveillance at the human-animal interface . develop and evaluate innovative approaches for influenza surveillance and monitoring with other existing disease monitoring systems . studies to address challenges on data, clinical specimens, and viruses sharing with consideration for local, ethical, legal, and research perspectives . examine the timeliness and quality of data required for early detection from local to regional, national, and global levels role of modeling in public health decision making five priority public health topics were identified for an inter-pandemic seasonal influenza scenario as follows: . integration of genetic and epidemiological data to understand spatiotemporal spread to forecasts evolution for vaccine strain selection and to anticipate likely burden of disease . quantifying the relative contributions of different modes of transmission of human influenza and developing mechanistic modeling of transmission processes . research using data-capture technologies to characterize human contact and mobility patterns at local, regional, and global scales, and their correlation with transmission risk . integration of genetic, antigenic, and epidemiological analyses to optimize surveillance for newly emerging pathogens at the animal ⁄ human interface . identifying and quantifying human and environmental ecological, behavioral, and demographic determinants of the risk of cross-species transmission and pandemic emergence modern tools for strategic communication four priority public health topics were identified for an inter-pandemic seasonal influenza scenario as follows: . review of evidence and experience related to health crisis communication from fields to organize knowledge and support evidencebased practice in strategic communication . identify and develop tools to rapidly and accurately monitor knowledge, attitudes, and practices in different population groups and guide future communication efforts . identify and develop communication tools and approaches for cultural settings and communities to practice and promote appropriate risk reduction measures . understand the potential ethical, social, economic, and political communication in crisis and develop strategies to work within constraints while maximizing opportunities complemented by an analogous research roadmap for a pandemic influenza scenario, the research topic recommendations for an inter-pandemic period represent an important outcome of joint international efforts by who, academicians, and public health experts. implementation of the identified research priorities is expected to underpin public health decision-making at all levels with proven knowledge that will help to save large numbers of lives, reduce health costs, and economic loss and mitigate potential social disruption over a medium-tolong term period. the impacts of school resumption on the incidence of pandemic (h n ) in school students introduction school closure is one non-pharmaceutical intervention that is often suggested in pandemic preparedness plans, and it was widely implemented in pandemic (h n ) to reduce transmission amongst school students. however, from past epidemiological studies, the effect of school closure in reducing respiratory disease transmission was inconclusive. given this public health intervention causes major disruption to the education system and potentially raises childcare issues to working parents, evaluating its effect in the recent pandemic is necessary to improve future pandemic planning. in hong kong, since school closure was implemented early in the pandemic and closure was effectively continued with the commencement of summer holiday, the lack of incidence data in the absence of school closure makes it difficult to analyse its effect directly. this has prompted us to analyse the situation indirectly from the angle of school resumption after summer holiday. in hong kong, public health surveillance on pandemic (h n ) was effective from th april- th september : healthcare professionals were advised to report suspected cases of infection to centre for health protection, department of health, hksar, for further laboratorial confirmation. demographics of reported cases were subsequently recorded into a computerised system (the ''e-flu'' database). following institutional approval, a dataset of all confirmed cases diagnosed from may to september was obtained, which included the age, gender, confirmation date, and notification date of each report. all cases were classified into four defined socio-economic classes by age: pre-schoolers ( - ), school students ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) , adults ( - ), and retirees ( ‡ ). assuming cases had contracted infection on the earlier date between confirmation and notification, daily incidence in each age class was counted for epidemic curve construction. upon observing an unusual rise in the epidemic curve of school students when school season resumed in september, interrupted time series analysis (also known as intervention analysis) was applied to obtain the statistical significance of this observation. the analysis was applied to the incidence in school students from th july to th september , which covered the period from the start of summer holiday to the end of the th week of new school season. incidence in school students before summer holiday was deliberately dropped since not all schools were closed when the school closure policy was effective: all primary schools were closed proactively, whereas secondary schools were individually closed on a reactive basis if students were identified to have contracted the infection. school activity was formulated as a step function, which takes value from st september onwards (st = : t < st september, st = otherwise). a range of times series models were fitted by the maximum likelihood method and aic (akakine information criterion) was used to select the one with best fit. all computations were performed in sas version . . a total of ( ae %) pre-schoolers, ( ae %) school students, ( ae %) adults, and ( ae %) retirees were diagnosed with the infection in the surveillance period. the epidemic curves of preschoolers, school students, and adults showed a steady rise from th june onwards when local transmission of pandemic influenza was identified. an upsurge in the epidemic curve of school students can be observed in early september, coinciding with the commencement of the new school year (figure ) . interrupted time series analysis on the epidemic curve of school students returned an arima( , , ) model with equations: where st, yt, yt denote school activity, predicted and actual incidence in school students on day t, respectively. standard error and significance for model constants were: ae (se = ae , p = ae ), ae (se = ae , p = ae ). in short, the model can be interpreted as: the number of infected school students rose by ae per day on average during the entire study period, with a sharp increase by ae coming into effect when the new school year began. time series analysis showed, at the marginally significance level, that daily incidence in school students had a major increase when school season resumed. on the assumption that the increase was not caused by any change in health seeking behaviour, this result suggests that school resumption had facilitated transmission amongst school students. on the basis that school activity significantly increases incidence of pandemic influenza in school students, this study suggests closures of schools in the early phase of pandemic (h n ) and subsequently in the summer holiday probably had a major effect in mitigating transmission amongst school students. youngsters were postulated to be major vector for transmission in pandemic (h n ) . if this were true, it would be reasonable to expect the epidemic curves of the other age classes to show a similar upsurge when one is observed in school students. the absence of such observation in the epidemic curve of hong kong suggests school students were mostly disseminating the virus amongst themselves, but not to the other age groups. in november , gip convened the first global consultation on a public health research agenda for influenza to identify key research topics in each of the five main streams of public health research. during this meeting, the scientific working group (swg) of the sub-stream in ''modern tools for risk communication'' identified the requirements in research during influenza pandemics and inter-pandemic periods to provide clear, credible, and appropriate messages which meet the needs of diverse communities. the swg suggested that who hold a follow-up workshop to assess the use of modern tools related to strategic and risk communication and to further promote research in these areas. communication'' in may . one of the main objectives of the meeting was to generate a roadmap of public health research priorities related to strategic and risk communication. the research roadmap was developed by the group of invited experts on the basis of an analysis of available evidence and experience on public health and health crisis communication from relevant disciplines across global regions, as well as critical assessment of existing communication methods related to influenza control in different cultural, social, and ethnic settings. the workshop consisted of a series of presentations by experts in relation to experiences and lessons learned about communication during the sars, h n epidemic, and h n pandemic. there were also a series of group discussions on identifying research needs for pandemic and interpandemic periods in order to strengthen the research agenda. the expert group identified important public health needs in relation to communication during pandemics as well as in the inter-pandemic times. the main topics of discussion centered on communicating issues of influenza virus transmission, the use of influenza vaccines safety and efficacy, and use of antivirals as well as definition of the severity of the pandemic and the phase changes. in this context a number of research areas were identified, which can be broadly classified into four areas: understanding of communication principles and mechanisms is associated with an array of research topics covering different subject areas. one of the key questions here relates to the link between communication and ''behaviour change'' models and their application and appropriateness for different settings. the expert group defined the term ''behaviour change'' in this context as the modification of behaviour towards better health practices that are supported by clinical and scientific evidence for personal protection against infectious diseases and other adverse health risks. research topics related to these models require understanding and differentiating information and ''behaviour change'' needs of different audience segments, such as stakeholder mapping, target audience analysis, research into behaviour motivation, social norms, and the cultural, religious, social, legal, and political barriers and enablers of particular behaviors that are beneficial in influenza control. this research area also includes the analysis of media consumption among different audiences, role models, including ways to analyse how rumours and misinformation are spread, and ways to provide evidence-based information correctly. other important areas of investigation embrace methods to communicate uncertainty, learning how to build trust while communicating about a pandemic, and understanding what needs to be done before, during, and after a pandemic in order to create the best environment for influenza pandemic communication. critical key audiences identified for more intensive analysis were health workers, religious, public health, and societal (political and community) leaders. • investigation of the role of different communication channels and communication formats for different target audiences in a pandemic, particularly for groups that are ''hard-to-reach.'' • determining effects of perceptions related to pandemic influenza (severity, susceptibility, response efficacy, self efficacy, perceived social norms) on protective behaviours in different groups. • understanding audience in terms of their knowledge, preventive activities, and reasons why engaged ⁄ not engaged. • developing mechanisms to synergies between risk communication and behavior oriented approaches in the pandemic and inter-pandemic phases. • determining social, economic, cultural, and religious factors which support behaviours to limit spread and minimize impact in different settings. • identification of the key predictors ⁄ factors that influence people's behavior among different groups and populations vis-à -vis pandemic flu behaviors. • identification of elements that contribute to trust among populations and in different settings (country, public, professional, community), particularly where trust was previously compromised. • understanding psychology of different groups regarding their response to uncertainty, and finding the best way to communicate uncertainty. the research questions in this section relate to the planning, development, and evaluation of tools that can be quickly accessed and used in a pandemic situation. these may include communication materials and channels; the setting up of key stakeholder and champion communication networks; research protocols that are ready for rapid assessment during a pandemic or new communication tools. the use and understanding of terminology and language by both lay and professional groups and communities in planning for and ⁄ or reacting to a pandemic are important areas of research. acute examples, such as the naming of the viruses or the use of the word ''pandemic,'' illustrate this need well. the research focus of this area is to look at lessons learned from the a(h n ) pandemic and to document and evaluate case studies, both looking at best practices, challenges, and barriers that were experienced. different communication strategies need to be evaluated and models to be built not only in terms of reach, but also in terms of impact on thinking, emotional response, and behavioural modification. a key question was how to prepare communication for a pandemic and how can the pandemic communication contribute to longer term ''behavioural change.'' mathematical modelling on gauging outcomes of such ''behaviour change'' would provide strategic approaches in risk communication. this section aims to answer the question whether the modeling, mapping, and scenario planning are actually useful in the pandemic situation. the expert group agreed that the research on the above issues should use a variety of methods and engage a number of disciplines. this would include literature reviews, case studies, trials, ethnographic studies, modelling, surveys, network analysis, as well as any other useful methodology. in an inter-pandemic situation for actual behaviour under pandemic conditions. • study the synergies and develop priority research topics on strategic ⁄ risk communication for influenza under inter-pandemic situations that includes zoonotic and seasonal infections. the who public health research agenda for influenza initiated and facilitated a multi-disciplinary discussion for communication during pandemic and inter-pandemic situations. it focused on both theoretical and practical issues to improve practice and ensure the health of the public for influenza. critical areas for research were identified to build evidence in this field. it was recognized that there are extensive bodies of knowledge in a number of disciplines, , such as health promotion, behavioural psychology, social sciences, social and behaviour change communication, social marketing, and communication for development relating to these questions, and that these should be explored. outcomes of these research activities are expected to widen the evidence base which will support developing communication strategies for influenza by countries, institutions, and individuals and will, consequently, help to improve public health world-wide. abstract background: cytokine dysregulation contributes to the unusual severity of h n (reviewed in ). previously, we demonstrated that interferon regulatory factor (irf ) and p map kinase (p ) signaling pathways separately contribute to the induction of pro-inflammatory cytokines and chemokines in h n -infected cells. here we investigate the role of innate sensing receptors in the induction of these cytokines and chemokines in response to h n and seasonal h n infection. materials and methods: human macrophages derived from peripheral blood monocytes were infected with h n ( ⁄ ) or seasonal h n ( ⁄ ) viruses. the role of innate sensing receptors in cytokine and chemokine induction by h n virus was investigated using transient knock-down of these receptors with sirnas. the expression of innate sensing receptors in infected cells, and as a result of paracrine activation (by virus free supernatants of infected cells) of adjacent uninfected cells were also monitored by real-time pcr and ⁄ or western blotting. the involvement of janus kinase (jak) signaling pathways in these autocrine ⁄ paracrine cascades was investigated using a jak inhibitor. results: we previously showed that tnf-alpha, ifn-beta, and ifn-lambda are the key mediators directly induced by the h n virus in primary human macrophages with other cytokines and chemokines being induced as part of a secondary autocrine and paracrine cascade. here we demonstrated that retinoicacid-inducible gene i (rig-i) rather than toll-like receptor (tlr ) plays the predominant role in h n -induced cytokines and chemokines in human macrophages via the regulation of irf and nf-kb nuclear translocation. in addition to the effects on virus infected cells, paracrine interactions between macrophages and alveolar epithelial cells contributed to cytokine cascades via modulation of jak signaling and by the upregulation of sensing receptors. conclusions: h n directly induced tnf-alpha and ifnbeta mainly via rig-i signaling, and the subsequent activa-tion and nuclear translocation of irf and nf-kb in human macrophages. in addition to the effects on cytokine signaling, the innate immune sensing regulators themselves were also up-regulated by h n infection, much more so than by seasonal influenza infection, via jak signaling. the up-regulation of innate sensing receptors was not limited to the infected cells, but was also found in adjacent uninfected cells through paracrine feedback mechanisms. this may lead to broadened and amplified cytokine signals within the microenvironment of the infected lung. a more precise understanding of the signaling pathways triggered by h n virus leading to cytokine induction may provide novel options for the design of therapeutic strategies for severe human h n influenza and also for treating other causes of acute respiratory disease syndrome. human h n infection is associated with a mortality rate of more than %. the basis for the unusual severity of h n disease has not been fully explained. cytokine dysregulation has been suggested to contribute to the disease severity of h n (reviewed in ). however, signaling pathways involved in the cytokine induction by h n virus are not fully understood. previously, we demonstrated that irf and p map kinase (p ) are separate signaling pathways which contribute to the induction of pro-inflammatory cytokines and chemokines in h n -infected cells. rig-i and melanoma differentiation-associated gene (mda ) are important cytosolic sensors of nucleic acid of pathogens, while tlr and tlr also recognize nucleic acid species of pathogens, but they are localized at the endosomal membrane. rig-i was found to be responsible for the recognition of influenza a virus infection, and the transfection of vrnps induces ifn-beta expression. while many studies have shown the role of rig-i in the induction of ifn-beta by influenza virus infection, the majority of these studies used either immortalized cell lines or mouse embryonic fibroblasts. there is a lack of data on the role of these innate sensing receptors in highly pathogenic avian influenza h n infection in primary human cells in vitro, which are more physiologically relevant. furthermore, there is little data on the autocrine and paracrine up-regulation of these innate immune sensors following virus infection. human macrophages were obtained from peripheral blood monocytes by adhesion and differentiation in vitro for days in rpmi medium supplemented with % autologous plasma. the cells were infected with h n ( ⁄ ) or seasonal h n ( ⁄ ) viruses at a moi of ae . a cells were obtained from atcc and cultured in mem medium supplemented with % fcs and % penicillin and streptomycin. the role of innate sensing receptors in cytokine induction by h n and h n viruses was investigated using transient knock down of these receptors with sirnas in human macrophages as previously described using specific sirnas purchased from qiagen. immunofluorescence staining assay of irf and nf-jb was employed to detect the nuclear translocation of these transcription factors after h n infection. rabbit polyclonal antibodies against human irf and and nf-kb were obtained from santa cruz biotechnology. goat anti-rabbit igg antibody conjugated with alexa fluor was a product of molecular probes. for investigation of paracrine effects on rig-i and tlr expression, culture supernatants collected from mock, ⁄ or ⁄ infected human macrophages were used to treat uninfected cells. the supernatants were first passed through a filter with -kda cut-off. virus particles as well as molecules with a molecular weight higher than kda were retained and removed, while the filtrate was collected for treatment of uninfected cells. the expression of innate sensing receptors in infected cells and in adjacent uninfected cells following paracrine activation by virus free supernatants of infected cells was monitored by real-time pcr. the involvement of jak signaling pathways in these paracrine cascades was investigated using a jak inhibitor (calbiochem). we previously showed that tnf-alpha, ifn-beta, and ifnlambda are the key mediators directly induced by the h n virus in primary human macrophages with others being induced as part of a secondary autocrine and paracrine cascade. in this study, we demonstrate that knockdown of rig-i or tlr led to the reduction of ifn-beta and tnf-alpha in human macrophages by both ⁄ (h n ) and ⁄ (h n ) infection. as shown in figure a , ⁄ virus induced higher level of ifn-beta mrna expression than ⁄ infection. cells transfected with rig-i or tlr sirna significantly reduced the expression of ifn-beta after ⁄ infection, by % and %, respectively. rig-i silencing also significantly reduced the ifn-beta expression in ⁄ infected cells by %. in contrast, silencing of mda or tlr did not suppress the induction of ifn-beta by either ⁄ or ⁄ infection; in fact, there was a slight ( %) increase of ifn-beta in cells transfected with mda sirna. based on these results we conclude that while both rig-i and tlr contribute to h n -induced interferon-beta induction in human macrophages, rig-i plays the dominant role. in order to investigate the relationship between these innate sensing receptors and the activation of transcription factors irf and nf-jb, we next measured the nuclear translocation of irf and nf-jb in cells with rig-i or tlr silencing after h n infection. immunofluorescence staining assay on irf and nf-jb was performed and the number of cells with nuclear translocation was quantitated. the percentages of cells with nuclear translocation were plotted in figure b . we demonstrated that rig-i knockdown led to a significant reduction of irf nuclear translocation after ⁄ infection, whereas the nuclear translocation of nf-jb after ⁄ infection was significantly suppressed by rig-i or tlr silencing. these results suggest that the involvement of rig-i and tlr in the cytokine induction by ⁄ was via the regulation of irf and nf-jb nuclear translocation. since rig-i and tlr are important in influenza a virus-induced cytokine expression, we next explored the expression of these innate receptors in neighboring uninfected human macrophages by treating the uninfected macrophages with the filtered culture supernatants collected from mock, ⁄ , or ⁄ infected macrophages. as shown in figure a , ⁄ supernatant differentially induced the mrna expression of rig-i, mda , and tlr compared to ⁄ supernatant treated human macrophages. the induction of rig-i was higher than the induction of mda and tlr . in the presence of lm of jak inhibitor, the up-regulation of all three innate sensing receptors was significantly reduced showing their induction was dependent on jak activity. human lung epithelial a cells were also treated with the supernatants collected from macrophages infected with mock, ⁄ , or ⁄ virus. differential induction of rig-i, mda and tlr by ⁄ supernatant compared to ⁄ supernatant treated cells was observed (figure b) . ⁄ supernatant dramatically induced all three innate sensing receptors, while ⁄ supernatant only marginally induced rig-i and mda , but not tlr . as in human macrophages, treatment with lm of jak inhibitor caused a significant suppression of ⁄ supernatantinduced rig-i, mda , and tlr expression in a cells. these results, taken together with the direct effects on virus infected cells, suggest that paracrine interactions between macrophages and alveolar epithelial cells contributed to cytokine cascades via modulation of jak signaling and by the up-regulation of innate sensing receptors. h n directly induced ifn-beta ( figure ) and tnf-alpha (data not shown) mainly via rig-i signaling and the consequent activation and nuclear translocation of irf and nf-kb in human macrophages. these results were consistent with a previous study using beas- b cells showing the essential role of rig-i in ifn-beta reporter activity by h n influenza virus infection. while tlr also played a role in induction of ifn-beta and the activation of irf and nf-kb, it plays a less important role compared to rig-i. the reduction of irf and nf-kb activation was also confirmed with the study by le goffic showing differential regulation of irf and nf-kb by rig-i and nf-kb can also be regulated by tlr . in addition to the direct role of rig-i and tlr in sensing and signaling the presence of influenza virus, the innate immune sensing regulators were themselves also highly upregulated in both infected (data not shown) and adjacent uninfected cells by influenza virus infection. compared with seasonal h n virus, the h n viruses had a much more dramatic effect on inducing innate sensing receptors via jak signaling pathways activated by autocrine and paracrine mediators. the up-regulation of rig-i, mda , and tlr was markedly induced by virus free culture supernatants from h n -infected macrophages, while supernatant from ⁄ -infected cells induced the expression of these receptors only to a lesser degree. the soluble mediators in the virus infected cell supernatant caused paracrine upregulation of rig-i, mda , and tlr in uninfected macrophages as well as human lung epithelial cells. these effects may lead to broadened and amplified cytokine signals within the microenvironment of the infected lung. taken together these results provide, at least, part of the explanation on the hyper-induction of cytokines in h n infection. a more precise identification of the signaling pathways triggered by h n virus leading to cytokine induction may provide novel options for the design of therapeutic strategies for severe human h n influenza and also for treating other causes of acute respiratory disease syndrome. we generated mutants of y (h n ) and a ⁄ duck ⁄ hokkaido ⁄ vac generation and characterization of mutant viruses rgy sub (h n ), rgvac sub (h n ), and rgvac ins (h n ), which have a serial basic amino acid residues at their ha cleavage sites were generated by site-directedmutagenesis and reverse genetics. rgy sub (h n ) and rgvac ins (h n ) required trypsin to replicate in mdck cells, and showed similar levels of growth to their parental viruses (table ) . chickens intravenously inoculated with rgy sub (h n ) or rgvac ins (h n ) did not show any signs of disease. rgvac sub (h n ) replicated in mdck cells without exogenous trypsin, and one of the eight chickens inoculated with the virus showed slight depression at day post-infection. the h and h mutant viruses were serially passaged in the air sacs of chicks to assess their ability to acquire pathogenicity. plaque formation in mdck cells and pathogenicity in -day-old chicks and -week-old chickens are shown in table . rgy sub (h n ) replicated in mdck cells in the absence of trypsin and killed all of the chicks after six consecutive passages. two of the eight-four-weekold chickens inoculated intravenously with rgy sub-p (h n ) died within days. eventually, over % of the chickens intravenously infected with rgy sub-p (h n ) died by days post inoculation, and its pathogenicity was comparable to that of hpaivs. rgvac sub-p (h n ) was pathogenic to both chicks and -week-old chickens, and mortality increased after one more passage. rgvac ins-p (h n ) replicated in mdck cells in the absence of trypsin, killed all of the chicks, and caused % mortality among -week-old chickens. the lethal effect of rgvac ins-p (h n ) on chickens increased with one additional passage in the air sacs of chicks, as in the case of rgvac sub (h n ). to examine whether the pathogenicity of each virus via the natural route of infection correlated with that by intravenous infection or not, three -week-old chickens were challenged intranasally with the viruses at an eid of ae and observed for clinical signs until day post-infection (data not shown). all chickens inoculated with rgy sub-p (h n ) or its parental viruses survived without showing any clinical signs, and serum antibody responses were detected in the hi test. on the other hand, rgvac sub-p (h n ) and rgvac ins-p (h n ) were pathogenic as in the intravenous experiment, killing two of three chickens by day post-inoculation. one of three chickens were not infected with rgvac sub-p (h n ) or rgvac ins-p (h n ) via intranasal route (data not shown), indicating these p viruses had not been completely adapted to the host. to investigate the possibility of these p viruses to acquire further pathogenicity for chicken, rgvac sub-p (h n ) and rgvac ins-p (h n ) were obtained from the brain homogenates of the chickens that died on days post intranasal inoculation with the p viruses. although mortality rate of chickens inoculated with the p viruses was equal to that with p viruses, enhancement of pathogenicity was observed in intranasal inoculation study; all of the chickens inoculated with rgvac sub-p (h n ) were infected, and time to death was shortened to - days post inoculation in chickens with rgvac ins-p (h n ) (data not shown). to investigate whether tissue tropism of the viruses was involved in their pathogenicity, we determined viral titers in the tissue and blood samples from -week-old chickens intranasally inoculated with each virus on days post infection ( table ) . rgy (h n ) and rgvac (h n ) were scarcely recovered from the samples, and the mutant strains before passage showed broader tissue tropism than the parental viruses. none of the chickens inoculated with rgy sub-p (h n ) showed any signs of disease, and viruses were recovered from each of the samples except the brain and the blood. one chicken inoculated with rgvac sub-p (h n ) showed clinical signs such as depression, and viruses were recovered from virtually all of its organs and blood samples. two of three chickens inoculated with rgvac ins-p (h n ) showed disease signs, and one died days post inoculation. the viruses were recovered from almost all samples of the two chickens showing signs of disease. p viruses were efficiently replicated in systemic organs of the chickens as compared with p viruses. throughout the study, the viruses were recovered from the brains of all of the chickens showing clinical signs. here, we demonstrated that the h influenza virus acquired intravenous pathogenicity after a pair of di-basic amino acid residues was introduced into the cleavage site of the ha and passaged in chicks. rgy sub-p (h n ) killed % of chickens infected intravenously, and its pathogenicity was comparable to that of hpaivs (table ) . however, chickens intranasally inoculated with rgy sub-p (h n ) did not show any clinical signs of disease (data not shown). these results are consistent with a previous study in chickens that found some h influenza viruses did not show intranasal pathogenicity although their intravenous pathogenicity index was over ae , classified as hpaiv according to the definition by european union. ohuchi et al. reported that the insertion of additional basic amino acids into the h ha cleavage site resulted in intracellular proteolytic cleavage. other groups reported that h and h has tolerated amino acid mutations into their cleavage sites, and the viruses with the mutated has replicated in mdck and ⁄ or qt cells in the absence of trypsin. , the results in the present study is in agreement with these, namely, cleavage-based activation by a ubiquitous protease is not restricted to the h and h has. the intranasal pathogenicity of the h and h mutants were different (data not shown), although these viruses similarly replicated in mdck cells in the absence of trypsin and killed chickens by intravenous inoculation ( table ) . the viruses were recovered from the brain and the blood of some chickens infected with rgvac mutants (h n ), and morbidity was closely associated with viral titers in the brain (table ) . on the other hand, no viruses were recovered from the brain of chickens infected with rgy mutants (h n ), explaining why rgy sub-p (h n ) did not show intranasal pathogenicity. all the viruses passaged in the air sacs of chicks killed chicken embryos by hours post allantoic inoculation (data not shown). rgvac sub-p (h n ) and rgvac ins-p (h n ) were more pathogenic to chicken embryos than rgy sub-p (h n ); the allantoic fluid obtained from the embryonated eggs inoculated with the h viruses passaged in air sacs was turbid. it has been reported that infection of a highly pathogenic h virus were strictly confined to endotherial cells in chicken embryos or chickens. , therefore, it is suggested that endotheliotropism differed between the h and h viruses passaged in air sacs and affected their intranasal pathogenicity. taken together, it is assumed that rgvac sub-p (h n ) and rgvac ins-p (h n ) showed marked intranasal pathogenicity with high levels of viremia caused by replication in vascular endothelial cells, leading to invasion of the brain. in the intravenous experiment, rgy sub-p (h n ) easily reached systemic organs, including the brain hematogenously, replicated through the cleavage of ha by a ubiquitous protease, and then exerted its pathogenicity. further study including a pathological analysis is currently underway to test this hypothesis. for all hpai viruses of subtypes h and h known to date, the cleavage of ha occurs at the c-terminal r residue in the consensus multibasic motifs, such as r-x-k ⁄ r-r with r at position p and k-k ⁄ r-k ⁄ t-r with k at p , and leads to a systemic infection. early studies demonstrated that the ubiquitously expressed furin and pcs are activating proteases of hpai viruses. furin and pcs cleave the consensus multi-basic motif r-x-k ⁄ r ⁄ x-r with r at position p . however, replacement of p r by k and a nonbasic amino acid significantly suppresses the processing activities of furin and pcs. most of the type ii transmembrane serine protease identified so far recognize a single r at position p , but the newly isolated mspl and its transcript variant tmprss preferentially recognize paired basic residue, particularly r and k at position p , at the cleavage site. [ ] [ ] [ ] thus, mspl and tmprss can activate various bioactive polypeptides with multibasic residue motifs, including fusogenic viral envelope glycoproteins. the present study was designed to characterize the proteolytic processing of the hpai virus ha by mspl and tmprss in comparison with furin. hpai virus a ⁄ crow ⁄ kyoto ⁄ ⁄ (h n ) was isolated from embryonated eggs inoculated with tracheal homogenates from dead crows. then, the mutant ha sequence was constructed by changing r residue to k residue (n'-rkkr-c' to n'-kkkr-c') at the ha cleavage site by sitedirected mutagenic pcr as described. we used human cell line ecv , which expresses mspl and tmprss at levels below detection, and established the cells stably expressing mspl and tmprss , such as ecv -mspl and ecv -tmprss . to determine the cleavage specificities of mspl ⁄ tmprss and furin, peptides ( lg each) were incubated with ae mu mspl ⁄ tmprss for hour and furin for hours at °c, respectively. after incubation, the samples were separated by reverse-phasehigh-performance liquid chromatography (rp-hplc) with the use of a c column. the elution samples were then identified by amino acid sequence analysis and by maldi-tof-ms. we analyzed the cleavability of -residue synthetic peptides derived from ha cleavage sites of hpai strains, such as a ⁄ chick ⁄ penn ⁄ ⁄ (h n ) and a ⁄ fpv ⁄ rostock ⁄ (h n ), and low pathogenic strain a ⁄ aich ⁄ ⁄ (h n ). after incubation with human mspl or human furin, the digested samples were separated by rp-hplc, and peptide fragments were characterized by mass-spectrometry and protein sequencing. in contrast to the low cleavage efficiencies of the h ha peptide with a single r at the cleavage site ( figure a) , both the h ha peptide with the k-k-k-r motif ( figure b ) and the h ha peptide with the r-k-k-r motif ( figure c) were fully processed at the correct positions by mspl within hour. in the case of h ha peptide with multiple basic residues, mspl cleaved two carboxyl-terminal sides of r in the cleavage site sequence of n'-k-k-rfl-k-k-rfl-g-c', while furin cleaved only at a single site of r with r at position p , n'-k-k-r-k-k-rfl-g-c' in the presence of mm cacl . these cleavage site specificities of furin were consistent with that reported for the h ha peptide of hpai virus a ⁄ hong kong ⁄ ⁄ (h n ) with r-k-k-r motif. however, the h ha peptide with k at position p ( figure b) was hardly cleaved by furin under the same experimental conditions. tmprss showed similar results (data not shown). these findings suggest that mspl and tmprss cover diverse cleavage specificities, including non-susceptible specificity to furin. full length recombinant ha of hpai virus with kkkr cleavage motif was converted to mature ha subunits with membrane-fused giant cell formation in mspl or tmprss transfectant cells. in addition, this conversion was suppressed by bowman-birk trypsin inhibitor, a membrane non-permeable highmolecular mass inhibitor against mspl ⁄ tmprss . to test for the generation of infective virus, the conditioned media of -day culture of ecv -wt and ecv -mspl cells infected with wt and mutant hpai h n viruses were inoculated into newly prepared cells and cultured for hours. although spreading of wt virus infection with ha cleavage motif of r-k-k-r was detected from the conditioned medium of both ecv -wt and ecv -mspl cells, that of mutant virus with ha cleavage motif of k-k-k-r was only detected from the condition medium of ecv -mspl cells. these results strongly suggest that the expression of mspl, but not furin, potentiates multicycles of hpai virus with k-k-k-r ha cleavage motif. seasonal human influenza a virus has have consensus monobasic cleavage site sequence, n'-q ⁄ e-x-rfl-g-c', and all hpai virus has have two types of cleavage site sequences with multiple basic amino acids, n'-r-k ⁄ r-k ⁄ r ⁄ x-rfl-g-c' with r at position p in a large number of hpai viruses and n'-k-k ⁄ r-k ⁄ t-rfl-g-c' with k at position p in a small number of hpai viruses. figure shows furin efficiently cleaved synthetic hpai a ⁄ hong kong ⁄ ⁄ (h n ) ha cleavage site peptide with the r-k-k-r motif, but hardly cleaved the hpai virus a ⁄ chick ⁄ penn ⁄ ⁄ ha cleavage site peptide with the k-k-k-r motif. furthermore, cleavage of the full-length ha of hpai virus with r-k-k-r motif was detected, but cleavage of hpai virus ha with k-k-k-r motif was hardly detected in ecv -wt cells containing furin ( figure ). these substrate specificities of furin suggest that proteases other than furin and pc ⁄ play a role in the processing of has of hpai virus with k-k ⁄ r-k ⁄ t-r cleavage motif. mspl and tmprss show unique cleavage site specificities of the double basic residues at the cleavage site, and r or k at position p greatly enhanced the efficiency, which none of the other ttsps have shown similar substrate specificities so far. furthermore, infectious and multicycle viral replication along with ha processing was also noted in genetically modified mutant recombinant live hpai virus a ⁄ crow ⁄ kyoto ⁄ ⁄ (h n ) with k-k-k-r cleavage motif in ecv -mspl cells (figure ) . these results were supported by the data of two cleaved peptides by mspl in figure c . these findings suggest that mspl has diverse cleavage specificities and may cleave ha at least two sites, although multiplicity of the mutant hpai virus was observed under the conditions. these results also suggest that mspl and tmprss in the membrane might potently activate the ha membrane fusion activity of hpai viruses and promote their spread. highly pathogenic avian influenza viruses replicate in various organs in birds, and the ha processing proteases might be widely distributed in these organs. indeed, tmprss and mspl are ubiquitously expressed in almost all human organs tested and are highly expressed in lungs, leukocytes, pancreas, spleen, and placenta. , in addition, mspl and tmprss are strictly localized in the plasma membranes, suggesting that proteolytic activation of hpai virus ha occurs not only through the trans-golgi network by furin and pc ⁄ , but also on the cell surface by mspl and tmprss . the pb -f protein, which is translated from the + reading frame of the pb gene segment, has been linked to the pathogenesis of both primary viral and secondary bacterial infections in a mouse model. - a mitochondrial targeting sequence is located in the c-terminal portion of the pb -f open reading frame, and expression of full length pb -f has been associated with mitochondrial targeting and apoptosis in a monocyte dependent manner. , it has been theorized that enhanced virulence could result from mitochondrial disruption with subsequent cell death mediated by pb -f . , a suggested second function of the pb -f protein is that it enhances immunopathology by triggering the inflammatory response. , in earlier studies from our group, the pro-inflammatory phenotype was markedly upregulated when the pb -f from the pandemic strain was expressed, arguing that this protein may be an important virulence factor for highly pathogenic pandemic viruses. , in this report we analyze the pb -f protein's contribution to pathogenesis in a mouse model, examining both inflammation and cell death. pb -f proteins from a variety of epidemiologically important iav strains including all pandemic strains from the th century, a highly pathogenic avian influenza virus of the h n subtype, and representative seasonal strains were utilized to determine the relevance to pandemic disease. we demonstrate that macrophage mediated immunopathology, but not apoptosis, are relevant functions of pb -f proteins from past or potential pandemic influenza viruses. using the predicted amino acid sequences of the pb -f proteins from pr , a ⁄ brevig mission ⁄ ⁄ , ⁄ singapore ⁄ ⁄ , a ⁄ hong kong ⁄ ⁄ , a ⁄ wuhan ⁄ ⁄ , and a ⁄ vietnam ⁄ ⁄ , peptides from the c-terminal end were synthesized as described. an additional n-terminal peptide was synthesized from the pr sequence as a positive control (mgqeqdtpwilstghistqk) as described. a panel of viruses were reverse engineered as described , and included laboratory strain pr , a virus unable to express pb -f (dpb -f ⁄ pr ), or expressing the pb -f of the pandemic strain ( pb -f ⁄ pr ) or the truncated h n strain (beij pb -f ⁄ pr ). , in addition, : reassortants encoding pb gene segments from a *current address: department of immunology and microbiology, university of melbourne, melbourne, vic., australia. highly pathogenic avian influenza of the h n subtype (h n pb ⁄ pr ), or from a human h n strain (h n pb ⁄ pr ) were utilized along with their isogenic deletion mutants for pb -f (h n dpb -f ⁄ pr and h n dpb -f ⁄ pr ). cell lines and cell death assays raw . cells were grown under conditions as described. cells were infected with one multiplicity of infection (moi) of virus for - hours, or exposed to lm (final concentration) of peptides derived from the c-terminal portion of pb -f for hour. cells from the supernatant and monolayers were harvested, washed, and stained with annexin (apc) and propidium iodide (pi) (becton dickinson, san jose, ca, usa), then analysed for cell death as described. six-to eight week old female balb ⁄ cj mice (jackson laboratory, bar harbor, me, usa) were maintained in a biosafety level facility in the animal resource center and procedures approved by the animal care and use committee at sjcrh. infectious agents and peptides were diluted in sterile pbs and administered intranasally to anesthetized mice (n = - ) in a volume of ll ( ll per nare) and monitored for overt signs of illness and weight loss daily. following euthanasia by co inhalation, the trachea was exposed and cannulated with a gauge plastic catheter (bd insyte; becton dickinson, sandy, ut, usa). bronchoalveolar lavage fluid (balf) was collected, red blood cell depleted, and cellular content analyzed via flow cytometry as described. one way analysis of variance (anova) was used for multiple comparisons of cell death and cellularity of balf. a p-value of < ae was considered significant for these comparisons. graphpad prism version . for windows (graphpad software, san diego, ca, usa) was utilized for all statistical analyses. to assess the contribution of pb -f to inflammation, we utilized a panel of previously described reverse engineered viruses in the mouse infection model. , the effect of pb -f expression was observed clearly in the inflammatory infiltrate in response to infection in the lungs. deleting pb -f from pr or expression of the c-terminally truncated beij pb -f had a significantly reduced influx of macrophages ( figure a) . expression of the pb -f caused similar inflammatory effects as the pr virus. disruption of pb -f expression the virus containing the h n pb gene segment in a pr background also significantly decreased the inflammatory response compared to the virus maintaining the ability to express full length pb -f ( figure a) . however, no differences were seen that could be attributed to the h n derived pb -f . the lungs of mice infected with the panel of pb -f variant viruses were examined at hours. pathologic changes typical of pr viral infection were observed in all lungs. these typical findings included perivascular inflammation, airway necrosis, hemorrhage, and deposition of cellular debris (figure ). in the lungs of mice infected with pr or pb -f ⁄ pr , however, significantly more perivascular cuffing was noted, with a prominent increase in numbers of macrophages (figure a, c) . the overall number of inflammatory cells throughout the lungs, including both airways and alveoli, was quantitatively greater in these mice than in mice infected with dpb -f ⁄ pr or beij pb -f ⁄ pr ( figure b, d) . as the function and influence of pb -f protein on normal viral function is not currently understood, and given the abrogation of enhanced inflammation induced by the truncated pb -f beij ⁄ pr virus, we sought to elucidate whether the c-terminal domain of pb -f could alone induce this inflammatory response. mice were exposed to a panel of peptides and were euthanized hours later for collection of balf. significant influxes of macrophages into the balf were seen following exposure to c-terminal pb -f peptides derived from pr , the pandemic strains from (h n ), (h n ), and (h n ), and the h n virus compared to controls ( figure b) . similar effects were not seen with the peptide derived from a more recent h n strain, a ⁄ wuhan ⁄ ⁄ . when peptide exposed mice were followed for morbidity for days, peptides proven to induce a heightened inflammatory response correlated strongly with overt clinical signs of illness (data not shown). thus, the ability to cause lung inflammation appears to be a property of pb -f proteins of viruses containing pb gene segments reassorted directly from the avian reservoir. the pb -f protein may contribute to virulence by rendering the host cellular immune response ineffective through inducing apoptosis. we sought to determine whether this was an epidemiologically important function for combating the host immune response to infection by testing the ability of pb -f proteins from several different iav strains to cause cell death. we therefore infected raw . cells with the panel of recombinant viruses at an moi of for - hours. as has been demonstrated previously, , , pr virus induces significant cell death compared to uninfected controls ( figure c ). when raw . cells were infected with pr virus, necrotic death peaked hours after infection. viruses lacking the c-terminal portion of pb -f , including the dpb -f ⁄ pr and the beij pb -f ⁄ pr were unable to cause cell death ( figure c ). in addition, expression of the pb -f also did not cause significant increases in cell death over controls. expression of pb -f or deletion of pb -f in either an h n or h n pb gene segment background similarly did not alter the cell death phenotype. to examine additional strains for which we did not have isogenic virus pairs, we next exposed the balbcj mouse derived macrophage cell line raw . to the panel of pb -f peptides derived from pr , the pandemic strains from (h n ), (h n ) and (h n ), and the h n for hours. cell death in raw . cells was caused only by the peptides derived from the laboratory strain pr and the peptide derived from the pandemic strain ( figure d ). viability was not affected by exposure of raw . to peptides derived from other virus strains. we conclude from these data that the mechanism by which pb -f contributes to the pathogenicity of pandemic influenza is unlikely to be through its reported ability to cause cell death. these data presented here demonstrate that the lung inflammatory response is enhanced by the influenza a virus pb -f protein in a mouse model. this inflammatory response was characterized by increased cellular infiltration of macrophages into the interstitial and alveolar spaces of the lungs, as well as enhanced perivascular inflammation, airway necrosis, hemorrhage, and deposition of cellular debris. this augmentation was shown to be induced by pb -f proteins only from those strains contributing to the formation of all pandemic strains of the th century and from the currently circulating, highly virulent h n strains that constitute an imminent pandemic threat. the iav h n strains circulating in humans since around code for a truncated pb -f . these viruses may lack the cterminal residues responsible for the inflammatory effects demonstrated in this publication. additionally, recently circulating h n strains, in contrast to their pandemic forbear from , have lost the capacity to cause pb -f mediated inflammation through mutation of the c-terminus of this protein. in a novel h n iav emerged from an animal reservoir and caused a human pandemic. disease burden from this strain has been considered mild in contrast to the three pandemics of the th century. the reasons for this disparity in pathogenesis are unclear. an examination of the origins of the three th century pandemics shows that only the hemagglutinin (ha) and pb gene segments were reassorted directly from the avian reservoir in every case, suggesting gene products of one or both of these may be important. the ha surface glycoprotein provided the antigenic novelty required for the each virus to achieve pandemic status. however, the significance of inclusion of a novel pb gene segment in each of the th century pandemics is not yet understood. we show here that the pb -f of these pandemic strains contributes to virulence through induction of inflammatory responses. thus pb -f may serve as a marker of the pathogenicity of pandemic strains. since the h n strain codes a truncated pb -f of only predicted amino acids, the lack of pb -f mediated inflammation may account in part for its relatively lower virulence. , of the panel of pb -f proteins studied, only that from the laboratory strain pr was capable of rendering responding host-immune cells ineffective by induction of cell death. we therefore hypothesize that molecular signatures specific to induction of apoptosis may have been lost through genetic mutation of the pb -f gene throughout the evolution of the iavs. our findings suggest that this apoptotic function is unlikely to be important for the virulence of any of the known pandemics. rather, the inflammatory phenotype appears to be the dominant contribution of pb -f to pandemic disease. influenza virus-cytokine-protease cycles are principal mechanisms of multi-organ failure in severe influenza and therapeutic approaches introduction influenza a virus is the most common infectious pathogen in humans, causing significant morbidity and mortality, particularly in infants and the elderly. mof with severe edema is observed in the advanced stage of influenza pneumonia. however, the relationships amongst factors that induce vascular hyper-permeability in severe influenza remain unclear. it is reported that significant increases in levels of pro-inflammatory cytokine levels, such as tnf-a, il- , and il- b, affect host survival both positively and negatively. the inflammatory response affects cell adhesion, permeability, apoptosis, and mitochondrial reactive oxygen species, potentially resulting in vascular dysfunction and mof. in addition, iav infection up-regulates several cellular proteases including ectopic trypsin and mmp- . up-regulated ectopic trypsin mediates the post-translational proteolytic cleavage of viral envelope hemagglutinin (ha), which is crucial for viral entry and replication and the subsequent tissue damage in various organs. the aim of the this study was to define the pathogenic impact of cytokine storm in iav infection and the molecular mechanisms by which pro-inflammatory cytokines and proteases cause vascular dysfunction in animal model. weanling female mice aged weeks (c bl ⁄ crslc) were infected with iav ⁄ wsn ⁄ ( pfu) with and without treatment of pdtc ( . mg ⁄ kg), nac ( mg ⁄ kg), and ndga ( mg ⁄ kg). these inhibitors were administrated once daily for days after infection. the levels of cytokines in tissue homogenates were measured by elisa kits. the effect of inhibitors on viral replications was determined by real-time pcr. gelatin zymography and western blotting were conducted as reported previously. host cellular responses in the airway after iav infection figure shows schematic view of typical biological responses in the airway of mice after iav infection. an initial response before viral proliferation is significant increases in pro-inflammatory cytokine levels. immediately after cytokine inductions, there is a marked up-regulation of ectopic trypsin along with an increase in virus titer in the airway, lung, and brain. ectopic trypsin mediates the post-translational proteolytic cleavage of iav ha, which is crucial for viral entry and replication and the subsequent tissue damage in various organs. we also found that iav infection markedly induces mmp- and matrix degradation. just after the peak of viral proliferation, the innate and adaptive immune responses of protective immunity are induced for defense and recovery, or oppositely on rare occasions, mof with vascular hyper-permeability is started into the advanced stage of influenza. the levels of tnf-a and il- in the lungs were increased persistently for days after iav wsn infection, and that of il- b peaked at days - post-infection (figure a ). since these cytokine responses are associated with activation of nf-jb and ap- , we treated mice once daily for days with anti-oxidant inhibitors: pdtc and nac against nf-jb activation, and ndga against ap- activation. pdtc and ndga significantly suppressed the up-regulation of tnf-a and il- b (p < . ), and nac suppressed tnf-a (p < . ), and il- (p < . ) at day post-infection. gelatin zymography showed up-regulation of ectopic trypsin and mmp- in mice lung, brain, and heart during infection for days ( figure b ). trypsin and mmp- induction was inhibited by treatment with pdtc, nac, and ndga, probably via blockade of nf-jb and ap- binding in the promoter region of the genes. viral rna replication in various organs at day post-infection was suppressed by more than one order of magnitude by pdtc, nac, and ndga ( figure c ). suppression of viral multiplication and induction of cellular factors by pdtc, nac, and ndga, significantly improved the survival of mice at day post-infection, the late stage of infection ( figure d ). to elucidate the mechanisms underlying brain vascular dysfunction of influenza-associated encephalopathy, changes in the levels of tight-junction proteins, intracellular zonula occludens- (zo- ) and transmembrane occludin, and the matrix protein laminin, were analyzed by western blotting. marked reductions in the expression levels of tight-junction constituents were detected at day post-infection, which were partly rescued by pdtc, nac, or ndga (figure e ). no other tight-junction protein, claudin- or matrix fibronectin and type iv collagen, were affected. the present study reports several new observations: (i) proinflammatory cytokines, tnf-a, il- b, and il- , when up-regulated by iav infection, induce trypsin and mmp- expression in various organs in mice; (ii) inhibitors of nf-jb and ap- effectively suppress the up-regulation of proinflammatory cytokines, trypsin, and mmp- and improve survival rates of infected mice. based on these results, we propose the 'influenza virus-cytokine-protease cycle' hypothesis as one of the mechanisms of vascular dysfunction in mof with cytokine storm in severe influenza and influenza-associated encephalopathy. the significance of pro-inflammatory hyper-cytokinemia, or 'cytokine storm,' in the pathogenesis of iav infection remains unclear. on the positive effects, cytokines promote lymphocyte activation and infiltration at the sites of infection and exert direct antiviral effects. however, on the negative effects of excess cytokines, the hyper inflammatory process evoked by viral infection may become harmful through intracellular activation of nf-jb, ap- , and the janus kinase-signal transducers and activators of transcription signaling pathways. , [ ] [ ] [ ] the in vivo experiments presented here showed that nf-jb and ap- inhibitors markedly suppress the expression of cytokines, trypsin, mmp- , and viral replication, resulting in a significant increase in the survival of infected mice. furthermore, cytokines interact with mitochondria to increase the production of reactive oxygen species, resulting in the production ⁄ activation of vasodilatory mediators such as nitric oxide and bradykinin, and subsequent endothelial dysfunction and edema in various organs. the molecular mechanisms underlying tight-junction disruption in endothelial cells and vascular hyper-permeability following the 'cytokine storm' remain unclear. tnfa up-regulation alters the cellular redox state, reduces the expression of four complex i subunits by increasing mitochondrial o ) production and depleting atp synthesis, decreases oxygen consumption thereby resulting in mitochondrial damage, , and increases [ca + ] i atp depletion dissociates zo- from the actin cytoskeleton and thereby increases junctional permeability. endothelial dysfunction induced by 'influenza virus-cytokine-protease cycle' in the early stage of severe influenza may further affect various circulating factors, coagulation factors and complement systems, and vascular interacting cells, such as neutrophils, macrophages and lymphocytes. mof is the final outcome of metabolic and mitochondrial fuel disorder, immunosuppression, endocrine disorder, and tissue injury followed by endothelial dysfunction in many organs. another key pathway of acute lung injury in the highly pathogenic avian influenza virus h n and acute respiratory syndrome-corona virus infection reported recently involves oxidative stress and formation of oxidized phospholipids, which induce lung injury via toll-like receptor signaling pathway. in addition to these data, up-regulated trypsin and pro-inflammatory cytokines may also affect tissue destruction and immunosuppression in the late stage of iav infection. further studies are required on the role of the 'influenza virus-cytokine-protease cycle' in the pathogenesis of mof, particularly in the late stage of viral infection. though influenza a virus replication kinetics and host responses have been previously studied in umbilical vein endothelial cell or transformed endothelial cell lines, the tropism of influenza a virus including h n and pandemic h n pdm for primary human lung microvascular endothelial cell has not been well defined. in this study we employed primary human lung microvascular endothelial cells, which are more physiologically relevant for understanding pathogenesis of influenza in the lung as to obtain a better understanding of the links of endothelial cell infection to systematic virus dissemination and multiple organ involvement in severe human influenza. supernatants of cells infected at moi of two were collected for cytokine protein assays, and total rna was extracted for gene expression analysis using qpcr. we found that seasonal influenza h n and h n viruses initiated viral gene transcription and viral protein expres- sion, but did not produce infectious progeny, while the highly pathogenic avian influenza h n and the pandemic influenza h n pdm virus could replicate even with the absence of exogenous protease (figure ) . furthermore, when compared to seasonal h n and h n , the h n virus was a more potent inducer of cytokine and chemokine including ifn-b, mcp- , rantes, ip- (figure ) , and il- , in virus infected endothelial cells, whereas h n pdm induced intermediate levels of cytokine and chemokine. avian influenza h n and pandemic h n pdm virus (but not the seasonal h n and h n virus) can productively replicate in human lung microvascular endothelial cells. this is likely to be of relevant to pathogenesis and provides a possible explanation for the extra-pulmonary infection seen in animal infection models. this extra-pulmonary spread may support the previous speculation and anecdotal evidence that h n and h n pdm virus can infect the gastrointestinal tract through the virus dissemination from the infected respiratory tract as the first target cells for influenza infection. [ ] [ ] [ ] in addition, the release of proinflammatory cytokine and chemokine induced by influenza h n and h n pdm virus infection in lung microvascular endothelial cells may be important contributors to the pathogenesis of severe human influenza disease leading to endothelial cell dysfunction that contributes to severe pulmonary disease symptoms. during its replication, influenza virus utilizes the host cellular machinery for many aspects of its life cycle. characterization of such virus-host protein-protein interactions is a must to identify determinants of pathogenesis. the m ion channel protein plays a crucial role during the entry and late stages of the viral life cycle where its c-terminal domain, well conserved among influenza a viruses, is accessible to cellular machinery after fusion with endosomal membrane and during its trafficking along the secretory pathway prior to assembly and budding. the aim of the study is to identify cellular interactants of m that play important regulatory roles during influenza infection. to identify cellular partners of m we performed a genome-wide yeast-two-hybrid (y h) screening approach using the cytosolic domain of m as bait and a human placenta random primed cdna library as prey and tested more than million interactions. from the y h screening, an interesting interaction with the human annexin a (anxa ) protein, a member of annexin family proteins that binds to phospholipds in a ca + -dependent manner, was identified. co-immunopre-cipitation of myc-tagged anxa and viral m proteins coexpressed in hek t cells after transfection and infection confirmed the direct interaction between anxa and m . we further investigated whether this interaction had any functional significance with regards to influenza life cycle. using a rna interference strategy to silence the anxa gene in human lung epithelial a cells, we observed increased progeny virus titers either in a single or multiple viral growth kinetics study, suggesting a negative regulatory role for anax during viral infection (figure ). a novel interaction between m and anxa was identified. more functional studies are in progress to define precisely the potential negative regulatory role of this interaction during viral infection. a systematic dissection of the viral life cycle will be performed to identify the step(s) affected by the anxa cellular factor using specific assays such as real-time quantitative rt-pcr in a single or multiple viral growth kinetics study, cell transduction with ha-and m -pseudotyped lentiviral particles, virion attachment and internalization assay, immunofluorescence staining of np protein as a marker of viral ribonucleoproteins localization, viral polymerase activity measurement, and viral budding observation by electron microscopy. rna extraction was achieved by qiagen biorobot ez prior to respiratory multiplex pcr analysis. what remained of the extracted material of each specimen was stored by refrigeration at °c. electronic patient records were searched for parameters, such as c-reactive protein (crp), white cell count (wcc), length of admission in days, and patient co-morbidities. patients were divided into three groups according to clinical severity: mild, moderate, and severe. the 'mild' group comprised of those admitted for three days or fewer, or not admitted at all. the 'moderate' group comprised those who required admission to hospital for more than days as a result of swine flu, but who did not require admission to an intensive care unit (itu). the 'severe' group comprised those who had required itu admission. invitrogen ' · reaction mix': ae mm of each dntp + mm magnesium sulphate. primer ⁄ probe mix recipe applied biosystems fast real-time pcr system, 'respiratory multiplex' program. well content ll; thermocycler initial stage ae °c for minutes, then °c for minutes. subsequent cycles of ae °c for seconds followed by °c for seconds for cycles. sequence detection software version . (applied biosystems). of clinical isolates analyzed, all samples produced amplification of pdh material; produced amplification of both swine flu and pdh material. human male dna (lot no. at ng ⁄ l, applied biosystems) at concentration calculated at ae cells ⁄ ll was diluted from ) to ) , yielding mean average ct values of respectively ae , ae , ae , and ae . plotting log of cell number versus ct gave a y = mx + c line from which ct could be interpolated into cell numbers. for swine flu quantification, a sample of swine flu ct ae was diluted through ) to ) . it must be noted that due to variability in resultant swine flu ct values, repetitions at these dilutions were done using an rna carrier ( lg ⁄ l, qiagen; cat no. ) in place of rnasefree water. the ) concentration was positive in nine out of assays; this fraction was used in the calculation described by simmonds to obtain a copy number of targets per reaction by the equation copy value = )ln(f), where f is decimal fraction of failure rate. here, f = ⁄ = ae ; )ln ae = ae copies. a control curve was generated with ct values of ae , ae , ae , and ae giving copy values of , ae , ae , and ae , respectively. using excel (microsoft office, ), these control series were adapted into formulae to convert swine flu and pdh ct values into copy numbers of these elements per reaction. simple division derived a value for swine flu copy per pdh copy, but this was chosen to be expressed as swine flu copy number per human cells. this will be referred to as the 'c' value. forty-two patients had known clinical details; average age was ae , female to male ratio : , and average admission length of days. of the mild group (n = ), nine cases were not admitted to hospital. of the remainder, the mean average admission length was ae days. mean average c value for all samples was ae · , with a standard deviation of ae · ; geometric mean was ae , and median average was ae . log(mean average c value) is shown for each severity group and for identified risk factors in the 'mild' severity group (figures a, b respectively) . in each case variation was too great to yield statistical significance. figure shows the range of c values observed in the 'moderate' severity group. > - · ; < - · > - · ; < - · > - · ; < - · > - · ; < - · > - · ; < - · > - · ; < - · > - · ; < - · > - · ; < - · > - · ; < - · > · ; < · > · ; < · > · ; < · > · ; < · > · ; < · > · ; < · in a study by duchamp et al., no significant correlation was observed between viral ct value and presence or absence of cardiaorespiratory disease, myalgia, digestive symptoms, or upper or lower respiratory tract infection (although a trend was observed towards patients presenting with signs of upper respiratory tract infection). to our knowledge, no other study has used a dual pcr for analysis of respiratory virus concentrations, and no study has attempted to correlate biochemical markers with respiratory virus concentration. the data exhibited a spectrum of c values, from values < · ) to over · . the three severity group standard deviations all overlapped with each other, preventing statistical significance. analysis of co-morbidities showed a high mean average c value when asthma was present ( ae · ), but again this was associated with an excessive standard deviation. whereas the median average c value in the presence of asthma was higher than the overall average c value ( ae versus ae ), it was significantly lower than the median c value when no co-morbidity was documented ( ae ). there are multiple caveats that may be the cause of such variety of c values obtained. the duration between initial rna extraction and study pcr had a range of to days, with mean average delay of days. the degradation of viral rna is an important contributor to assay variance and failure; rna degradation in clinical samples has been studied. [ ] [ ] [ ] degradation of human dna in clinical samples may have occurred. several studies have chartered degradation of stored human dna. , with regards to sampling, the clinical collection of throat swabs is naturally variable according to the method of the collector. a small number of bronchoalveolar lavage samples were analyzed, yet did not amplify, presumably due to rna degradation. the upper respiratory tract may be only a physical stepping stone for the virus, and take no further role in pathogenesis of severe disease (although undoubtedly is crucial for transmission). interestingly, a ferret study of pathogenesis observed that swine flu yields from the upper respiratory tract were greater than those given by ordinary seasonal h n , with consequently increased shedding. the review by mansfield cites significant findings regarding influenza pathogenesis, including the predilection of h n strains for type ii pneumocyte cells and alveolar macrophages. it also highlights the limitation of knowledge through dearth of human autopsy studies; an exception is the recognition of haematophagocytic syndrome in severe cases. it is known that specific immunoglobulin is effective against establishment of infection in the upper respiratory tract, whereas specific cytotoxic t lymphocytes (ctls) are necessary for clearance of the virus from the lower respiratory tract. it is also suggestive that a gap of two whole days transpires between initial infection and instigation of a specific immune response. it is plausible that in the healthy individual, virus progression is confounded by efficient natural mucosal immunity, in part through good secretory immunoglobulin levels. airway inflammation associated with asthma exacerbation is known to increase both risk of respiratory viral infection and poorer outcome. it is unproven but likely that the local inflammatory processes give rise to increased virion burdens in the upper airways; however, the same effect is conceivable for epithelial cell turnover. there will likely be variance within each clinical category due to patient circumstances and clinicians' judgment of required admission. unfortunately, the duration of symptoms prior to swab collection was often omitted in the clinical notes. finally, stratification of patient group by receipt of antiviral treatment was not studied. no correlations were observed with c values and crp, wcc or admission length. trends were observed towards higher c values in 'mild' cases, but without statistical significance. the relative small study size, coupled with the intrinsic variability of the parameters studied, warrants larger, better controlled, prospective studies to elucidate clinical use of the c value for influenza illness prediction and management. in mid-april a novel variant of a(h n ) influenza virus began to spread rapidly throughout the world, causing the first pandemic of the st century. the majority of the cases associated with this new virus show to be mild, but severe and fatal cases have been reported. molecular markers associated with severity have already been identified, as is the case of the mutation d g. resistant viruses to antiviral drugs have also been identified, highlighting the importance of rapid determination of the antiviral drug profile. global a(h n ) genetic characterization, molecular evolution dynamics, antiviral susceptibility profiles, and inference of public health implications require nation and region wide systematic analysis of circulating virus. the objective of this ongoing research study was, primarily, to thoroughly characterize the genetic profile and evolution of the emergent influenza a(h n ) virus circulating in portugal and its phenotypic expression on antiviral drugs susceptibility. the cases considered in this study were obtained from the community and from two collaborating hospitals in lisbon -a reference hospital for adults (hospital de curry cabral) and a reference hospital for children (hospital dona estefânia). the cdc real-time pcr protocol, recommended by world health organization (who), was the method used to confirmed all influenza a(h n ) cases. from a total of a(h n ) positive cases diagnosed and confirmed, were selected for this study, taking in consideration that they should cover the period of epidemic activity in portugal and include cases from persons belonging to risk groups and cases associated with more severe clinical features. ninety-six a(h n ) strains were isolated in mdck-siat cells, from combined naso-oropharyngeal swabs. for the evaluation of the genetic profile of a(h n ) virus circulating in portugal, of the isolates were characterized by genetic analysis of the ha, na, and mp genes. the remaining five gene segments (pb , pb , pa, ns, and np) were also sequenced for six of this isolates. briefly, sequencing was performed according to the protocol developed by cdc and recommended by who, using bigdye terminator v. . technology. nucleotide sequences were determined in a dna automatic sequencer abi prism xl genetic analyzer. for each genomic segment, genetic analysis was performed with lasergene v. . software (dnastar inc, usa) using an average of - overlapping readings, including sense and antisense, for precise nucleotide and amino acid sequence determination. genetic mutation and phylogenetic analysis were performed by neighbor-joining method, using mega . software, against published sequences from the vaccine strain (a ⁄ california ⁄ ⁄ ) and from selected a(h n ) strains available on gisaid epiflu database. all mutations were identified with reference to the vaccine strain genome sequence. antiviral drug susceptibility profile of a(h n ) influenza virus circulating in portugal was evaluated both phenotypically and genotypically for nais and genotypically for amantadine. phenotypic evaluation to nais, oseltamivir and zanamivir, was performed for all isolates by ic determination through munana fluorescence assays. genotypic evaluation was performed by searching for mutations associated with resistance to nais in all na gene sequences. amantadine susceptibility profile was performed for all isolates by searching on m sequence for the molecular markers associated with resistance to this antiviral drug (l f ⁄ i; v a ⁄ d; a t; s n; g e). genetic characterisation of the ha subunit of ha reveals point mutations in different strains. all analysed strains present p s and i v mutations, which distinguish them from the vaccine strain ( figure a ). thirty-three of the sequenced strains group in the s t branch. this mutation is referred in the literature as being associated with the putative antigenic site ca. most of these strains ( ) further subgroup in the d e branch, this mutation being associated with one loop of the receptor-binding site. from the early to the late epidemic period, an increased circulation of virus carrying the mutation s t was observed. this is in agreement with the association between this mutation and an enhanced viral fitness that is described in the literature. additional mutations were also observed in a small number of virus, of which we highlight: regarding the genetic characterisation of na, the majority of strains analysed ( of ) presents the mutations n d and v i ( figure b) . as mutation s t in ha gene, these two na mutations are described in the literature as associated with enhanced viral fitness. the few strains not carrying these mutations have circulated in the beginning of the epidemic period. fifteen of the analysed strains further subgroup in y h branch. additionally, mutation i v was identified in two strains. for the remaining gene segments available for the six analysed strains, the observations include: (i) no previously described virulence markers in pb , pb -f , and ns were detected; (ii) pb -f protein is present in the truncated form of amino acids; (iii) the presence of mutations i v and l q in ns and v i in np; (iv) the described association of mutation i v in ns and v i in np genes with viral fitness. phenotypic evaluation of nais susceptibility revealed the existence of three minor and two major outliers to oseltamivir ( figure ). the two minor outliers exhibited a reduction of approximately twofold in the susceptibility to this antiviral drug, comparing to the baseline level, while the reduction exhibited by the two major outliers was of approximately three-and fourfold. regarding zanamivir, two minor outliers were identified with a reduction of approximately twofold in the susceptibility, compared to the baseline level. these two minor outliers (a ⁄ portugal ⁄ ⁄ and a ⁄ portugal ⁄ ⁄ ) correspond to the two major outliers identified for oseltamivir. genetic analysis revealed the presence of the mutation i v in the na sequence of these two strains. the contribution of this mutation for the profile of reduced susceptibility identified for both nais is not known, but a mutation in the same na position (i r) has been referred to as being associated with a reduction in nais susceptibility. full genome sequence analysis of these strains shows that both strains also present the v i mutation in pb gene. however, no association of this mutation with antiviral drug susceptibility is referred in the literature. concerning genetic evaluation of susceptibility to amantadine, all analysed strains present a serine in position , which is a molecular marker of resistance to m inhibitors. these preliminary results allow us to discuss several points. however, the additional data that is being obtained through this ongoing study will be essential for a more complete analysis. for example, more information is needed to determine if the mutations found alter the biology and the fitness of the virus or if there are associated with an increased prevalence of the virus. the majority of the mutations identified in ha subunit have been detected in a(h n ) strains distributed throughout the epidemic curve, not evidencing a specific evolutionary trend. this is in agreement with the genetic and antigenic homogeneity that has being described for a(h n ) virus. the occurrence of mutations in the position of the ha subunit of a(h n ) virus have been described. however, more studies are needed to clarify the outcome of these mutations, as for example in patients with severe complications. it could also be relevant to investigate the presence of single and mixed variants in viruses and in clinical specimens and the possibility of these mutations affecting the binding specificity. regarding the susceptibility of a(h n ) pandemic viruses to antiviral drugs, all analysed strains were found to be resistant to amantadine. this resistant profile was not unexpected since the mp gene from this new variant had originated in the eurasian swine lineage, which is characterised by being resistant to this antiviral drug. the majority of the a(h n ) strains analysed revealed to be susceptible to both nais, with only five strains exhibiting a profile of reduced susceptibility, three to oseltamivir and two to both nais. for these last two, the presence of the i v mutation in the na sequence could explain the reduction observed, but a more complete analysis is needed to confirm this. the french national pandemic plan includes an early containment phase followed by a limitation phase. the efficacy of such a plan depends on pre-existing surveillance and laboratory networks. the grog community surveillance network and the hospital lab networks organized by the two french nics carried out the virological monitor- the efficacy of such plan depends on pre-existing influenza surveillance and laboratory networks. in france, the community surveillance is carried through the grog surveillance network. in addition, surveillance is also carried out in hospitals by the renal network. this renal network is divided in two sub-networks: the so-called h -labs network, activated during the containment phase and the extended renal lab network activated in the limitation phase. the h -labs have bsl- facilities that can be used for diagnosis purposes. as part of the national influenza surveillance system led by the french institute for public health surveillance (invs), the grog community surveillance network and the lab networks linked to the two french nics carried out the virological monitoring of the a(h n ) pandemic from the early containment phase up until the end of the pandemic phase. during the containment phase, all suspected cases were hospitalized and declared to invs. each patient was tested on the same day by specific virological diagnosis. hospital admission was not mandatory during the limitation phase, (i) the clustered cases were monitored to study transmission chains, and (ii) the circulation of the virus in the community was monitored through grog swabs collected by practitioners. the nics organized the influenza surveillance to fulfill several objectives according to the epidemiological situation. first, rt-pcr tools (influenza a m gene rt-pcr and a(h n ) specific h and n genes rt-pcrs) were developped and distributed to the lab networks on the th of may . from the early phase, the nics and the h -lab network analyzed all the samples collected from hospitalized and community patients. during the early phase of the limitation phase, an increasing number of labs were performing the specific assays. when the pandemic wave started, all hospital labs could do the testing. results were centralised by nic and reported on a weekly basis. in addition, nics carried out the monitoring of antiviral resistance emergence (na pyrosequencing, specific h y rt-pcr, and phenotypic assays), and real-time surveillance of genetic changes involved in virus adaptation (pb ) virulence factors or antigenic variations (ha). this sequencing was carried out by the pf sequencing platform of the institut pasteur. the first imported a(h n ) influenza cases were observed from the th of april . a limited number of cases have been reported in may. local transmission could be detected end of may. clusters were observed in schools in june and in summer camps during summer. as opposed to the epidemiology of the a(h n ) virus in other european countries, no summer wave was observed in france. only a limited number of sporadic cases were reported up until october. early september, a significant number of cases presenting with influenza-like illness was reported (figure ). the virological investigation of these cases showed high prevalence of rhinovirus infection. this circulation of rhinovirus was a counfounding factor of the pandemic. the pandemic wave lasted weeks between mid-october and the end of december (week to week , figure ). the pandemic wave started week - in the ile-de-france area, and only week - in the rest of france. the peak was recorded week ( figure ). the impact of the pandemic was mainly observed in the - years group of age. overall, severe cases have been admitted to the hospital, and deaths have been recorded by the end of the pandemic wave. the major impact was observed in the - years group of age ( % of deaths recorded). amongst the severe cases and the deceased cases, % and % of cases had no risk factor, respectively. these specimens, were positives for h n , representing ae % of total influenza virus detections. only nine brisbane-like h n , brisbane-like h n , and eight b viruses have been detected in the same period of time. the weekly positive rate ranged from % to %. phylogenetic and antigenic analyses of the viruses collected during the pandemic wave did not show any emerging genetic or antigenic variants (figure a,b) . eight patients, all among cases presenting with severe illness, were infected by a virus harbouring the d g mutation in the ha. amongst the virus tested for antiviral susceptibility or screened for the h y mutation by or specific rt-pcr, only oseltamivir-resistant viruses related to the na h y mutation have been detected. one of these cases also had an i r mutation associated to a reduced sensitivity to zanamivir. all but one resistant virus were detected in treated immunocompromised patients. overall, eight patients presented a virus with the d g mutation in the ha. all these patients had a severe infection; one of these had also a h y mutation in the na asociated to oseltamivir resistance. the pandemic started by the end of april . although the first cases recorded were as early as the th of april, the epidemic wave associated with a widespread spread of the virus was only recorded in october. the french population did not have to face a summer wave, as observed in north america and in numerous european countries. , it is difficult to speculate the reasons for the lack of summer wave; the specimens collected were negative for influenza. moreover, during september, it was anticipated that school openings would be the trigger for the beginning of the pandemic wave. as a matter of fact, a significant increase of influenza-like syndromes were observed at that time, but the virological investigation carried out by the laboratories showed thta is was related to a very large epidemic of rhinovirus. the epidemic circulation of other respiratory viruses can be counfounding factors for the surveillance of the influenza epidemic clinical when the survellance is only based on collection of clinical information. the starting of the pandemic wave was heterogeneous in france. the ilede-france region (paris and its suburbean area), where the population is dense, experienced an early start as compared to the rest of france. however, once the pandemic started in the rest of the county, the epidemic curves were quite similar. the peak was reached at identical times, although it may have been delayed in some remote places in france. overall, we estimate that % of the french population consulted for an ili presentation. the impact was mainly observed in the - years groupe of. however, this age groupe represented only a limited number of severe cases and deaths. on the other hand, the - years groupe of age, where the prevalence was not high, was the age group where the majority of severe cases and deaths was recorded ( % and %, respectively). this data is consistent with the observational data reported by numerous other countries. according to the profile of hospitalized cases, a(h n ) was more aggressive than seasonal viruses. the number of admission to the hospital was ten-fold that observed during a normal influenza epidemic. even if the mortality was limited ( cases), the age distribution of the deceased patients was different as compared to seasonal influenza ( % mortality in < years of age). the lack of recordeable excess mortality has been interpreted to be the consequence of a very mild pandemic, milder than some seasonal epidemics. however, the median age of the fatal cases was much younger than those observed during the seasonal flu, leading to a mis-interpretation of the real impact of the pandemic. when the impact is measurered in loss of years of life, the impact of this pandemic is larger than seen with seasonal influenza, and is quite comparable to these of the two last pandemics. the pandemic preparadness of numerous countries, the develoment of new intensive care techniques and equipment, and the large use of antivirals have reduced the overall impact of this pandemic. these are new factors that should be taken into account when evaluating the real impact of the h n virus. the virological monitoring of the pandemic was achieved by the community-based and hospital-based sea- sonal influenza networks, reminding the importance of maintining such networks. the diagnosis of influenza in most of the patients was carried out by molecular techniques. it has been clearly stated from the beginning of the pandemic that near-patient tests were lacking of susceptibility and could not be used for patient management. the distribution of a set of validated and comprehensive techniques by the two nic was very helpfull for the monitoring of the pandemic and the patients. however, this diagnostic procedure change should not preclude maintaining virus isolation that is necessary for whole genome analysis, monitoring of antigenic changes, and phenotypic testing for antiviral testing. some of the mutants that have been recorded, including viruses with antiviral resistance phenotype or genotype, could be analysed from grown virus strains. it is striking that despite a large antiviral usage, only a limited number of isolates had mutations associated to resistance. however, the frequent isolation of such resistant virus was observed in immunocompromised patients that presented severe infections and long virus shedding. the impact of the pandemic is still under evaluation. sero-epidemiological analysis will be performed to asses for the real attack rate of the pandemic virus. as in other countries, it has been recorded that asymptomatic infections could be observed frequently. it is quite unlikely that the impact of the pandemic was reduced by the vaccination campaign, although this vaccination started on the th of november, just when the pandemic started in france. it is estimated that millions received the vaccination. pandemic strains of the influenza virus sporadically emerge, deviating from the regular endemic strains of seasonal influenza. in april , a novel pandemic influenza virus a ⁄ h n emerged, swiftly spreading across the world. immediately, domestic and international public health agencies were forced to develop containment and mitiga-tion strategies in response to the pandemic. however, the dynamics and transmission patterns of this novel virus are yet to be fully understood. simultaneously, seasonal strains of influenza (a ⁄ h n , a ⁄ h n , and b) continued to circulate in many nations. both pandemic and seasonal variants of influenza are responsible for significant morbidity and mortality. to characterize the dynamics of this disease and the variation within strains, a more detailed understanding of the patterns in viral shedding during natural infection is required. the majority of data on the patterns of viral shedding during influenza infection are a result of volunteer challenge studies. in these studies, volunteers are commonly screened for pre-existing immunity against the challenge strain and are of a certain demographic and age. information on the patterns of viral shedding in natural influenza infections, pandemic or seasonal, is limited but should provide greater generalizability. we describe the trends of viral shedding and clinical illness in community acquired cases of pandemic and seasonal strains of influenza. in , a community-based study was conducted to analyse the effectiveness of non-pharmaceutical interventions to prevent the spread of influenza in households. in , a similar community-based study was initiated to collect comparative data from individuals infected with seasonal and pandemic influenza. both studies were conducted with very similar protocols, involving households in total. the specimens and symptom data required for this study all arise from secondary infections ascertained in these two community-based studies. the recruitment process in both studies was essentially identical. index cases were first recruited from their healthcare provider if they presented with influenza-like illness (ili). this individual would be included in the follow-up if he ⁄ she tested positive for influenza virus infection by rapid antigen test (quickvue) and was the first person in his ⁄ her household that showed signs of ili in the previous weeks. follow-up consisted of three home visits that spanned approximately - days. at each home visit, nasal and throat swab (nts) specimens were collected from all household members, regardless of the presence or absence of symptoms. symptoms were recorded in daily symptom diaries provided for every household member, and digital thermometers were provided to record daily tympanic temperature. the symptoms recorded were fever ‡ ae °c, headache, myalgia, cough, sore throat, runny nose, and phlegm. influenza virus infection and subtype was identified by reverse transcription polymerase chain reaction (rt-pcr) on the nts specimens. viral shedding was quantified from the same specimens by rt-pcr to determine viral loads, as well as by quantitative viral dilutions to determine median tissue culture infectious dose (tcid ). the details concerning laboratory methods have been described in a previous study. all analyses in this study focus exclusively on secondary cases; these are household contacts of recruited index cases who acquire influenza virus infection following the initial home visit. index cases generally presented with a certain threshold of illness severity requiring medical attention, whereas infections among household contacts can vary from asymptomatic to severe representing naturally acquired influenza infections. these secondary cases must be negative for influenza for their first nts specimen, and subsequently tested positive. we analysed mean viral loads measured by rt-pcr and quantitative culture by plotting by day since acute respiratory illness (ari) onset according to strain of influenza (pandemic a ⁄ h n , seasonal a ⁄ h n , seasonal a ⁄ h n , and seasonal b). ari is the reference time point, because the day of infection is unknown and is defined as the presence of ‡ of the symptoms mentioned above. average symptom scores were also plotted according to ari onset and grouped into upper respiratory symptoms (sore throat and runny nose), lower respiratory symptoms (cough and phlegm), and systemic signs and symptoms (fever ‡ ae °c, headache, and myalgia). mean daily tympanic temperatures were also plotted since date of ari onset and according to strain of influenza virus. all analyses were conducted using r software (version . . ; r development core team). a total of households and individuals were followed-up in the two studies. of household con-tacts tested by rt-pcr, were found to be influenza positive. among these influenza infections, ( ae %) were asymptomatic (rt-pcr positive plus symptoms recorded), were subclinical (rt-pcr positive plus symptom recorded), and presented with an onset of ari during the follow-up period. from the cases with ari onset, seven pandemic a ⁄ h n , seasonal a ⁄ h n , seasonal a ⁄ h n , and seasonal b influenza virus infections were identified. the age distribution among secondary cases was observed to be largely comparable across the four strains of interest (table ). there were a lower proportion of males who acquired pandemic a ⁄ h n compared to the seasonal strains of the virus. cough was the most commonly reported symptoms during follow-up in cases of pandemic a ⁄ h n and seasonal b, whereas runny nose was most common in seasonal a ⁄ h n and a ⁄ h n cases. cumulatively, fever ( ‡ ae °c) was reported in approximately half ( %) of the secondary cases. patterns of viral shedding were analysed in a subset of influenza positive individuals who recorded an onset of ari in their symptoms diaries (figure ). household contacts that were asymptomatic, subclinical, or did not have an ari onset were excluded from the analysis. viral shedding in all three influenza a strains were recorded to occur on the day of ari onset or day post-ari onset. follow- ing the peak, measured levels of viral shedding declined steadily to undetectable levels over - days. the trend of viral shedding in influenza b infected individuals rose days before ari onset, fluctuated for around days before eventually resolving. the patterns of viral shedding over time measured by quantitative viral culture were generally similar to the patterns measured by rt-pcr. the patterns of symptoms and signs were comparable in the four strains of influenza included in this study, peaking on the day or day post-ari onset, and gradually declining over a period of - days. in all strains, systemic symptoms and signs were observed to resolved faster than upper and lower respiratory symptoms. the trend of tympanic temperature in each influenza strain was comparable to the respective symptom pattern. patterns of viral shedding observed in influenza a strain infections (pandemic a ⁄ h n , seasonal a ⁄ h n , and seasonal a ⁄ h n ) were broadly similar. the pattern differed from the observed pattern of viral shedding in seasonal influenza b infections. the majority of viral shedding in influenza a strains occurred at and near ari onset, whereas there were variable amounts of viral shedding preand post-ari onset for those with influenza b. the biological reason for this difference is yet to be clarified. these differences are consistently observed regardless of laboratory method used to quantify the viral loads. it was observed that viral shedding measured by tcid resolved more quickly than when measured by rt-pcr, suggesting that rt-pcr is more sensitive, but it could be detecting inactivated fragments of rna instead of active virus. the trends observed for the seasonal strains of influenza in this study were similar to those reported in literature. the patterns of symptoms and signs as well as tympanic temperature in the four different strains of interest in this study were found to be comparable. these patterns closely resemble the patterns of viral shedding observed in the influenza a virus strains, but not in the influenza b virus strain. the trends of viral shedding, symptom scores, and tympanic temperature for pandemic a ⁄ h n were similar to trends observed for seasonal a ⁄ h n and seasonal a ⁄ h n infections, suggesting that the dynamics of these viruses are largely the same. the clinical course of infection with pandemic a ⁄ h n influenza virus appeared to be similar to the seasonal b influenza virus, but the patterns of viral shedding over time diverges. in general, our results suggest that the dynamics of the pandemic a ⁄ h n virus were similar to the seasonal a ⁄ h n and a ⁄ h n viruses, and clinically similar to the seasonal b virus. this study faced sample size limitations; very few cases of pandemic a ⁄ h n were detected and the secondary attack rate in general was low, though a total of households were followed up. this lack of power led to the inability to analyse the differences between adult and children and other characteristics that could be correlated with amount of viral shedding. there are also biases that must be factored in during recruitment. the eligibility criteria of only healthy households could select for households with higher innate immunity. on the other hand, recruitment at health care providers can be biased towards index cases that had more severe illness that required medical attention. the strength of the study is the broad generalizability of the results due to the strict classification of secondary cases. the infections reported in this study were all community-based and should represent true natural infections. pandemic potency of the influenza virus is largely determined by its transmissibility. the first objective of this study was to model the transmission of influenza h n and h n viruses. at present, vaccination with laiv has been used as a widespread, effective public health measure for influenza prophylaxis. some unsubstantiated concerns have been raised about a potential possibility of reassortment of circulating influenza viruses with laiv viruses following vaccination with laiv. thus, another objective of this study was to assess the probability of pig-to-pig transmission of cold-adapted viruses and their potential reassortment with wt influenza strains. female albino guinea pigs weighing - g were inoculated intranasally with eid of virus without anaesthesia. transmission studies were then performed hours after inoculation. inoculated animals were housed at % relative humidity and °c in the same cage with noninfected guinea pigs or in cages placed m away from non-infected pigs. virus replication was determined by virus isolation in hen eggs and by pcr. sera were collected at and days post inoculation. seroconversions were assessed by routine hai test. genome composition of reassortants was monitored by rflp analysis. capacity of the viruses to grow at optimum, low, and elevated temperatures (ca ⁄ ts phenotype) was evaluated, and virus growth properties were observed following virus titration in hen eggs. when infected pigs were co-caged with non-infected (naïve) individuals, vn , indo ⁄ , a ⁄ california ⁄ ⁄ , and nibrg- were isolated in %, % ae %, and % of contact animals, respectively. serological confirmation of virus transmission was higher than virological data ( %, %, %, and %, respectively). in addition, it was shown that when pigs inoculated with a ⁄ california ⁄ ⁄ were co-caged with animals inoculated with nibrg- , they got infected with both viruses ( table ) . the ability of direct transmission of cold-adapted viruses was also investigated. data show that the a ⁄ ⁄ california ⁄ ⁄ laiv candidate was detected in the upper respiratory tract of ae % vaccinated pigs. the mdv was identified in % of infected animals. however, neither group of contact pigs, co-housed with the vaccinate pigs, had evidence of infection with cold-adapted viruses. in addition, none of the contact pigs had any evidence of seroconversion to the coldadapted viruses as determined by hai assay. it was also most interesting to note that pig-to-pig transmission of the highly transmittable nibrg- reassortant virus was not seen when pigs, vaccinated with mdv, were co-caged with animals infected with nibrg- virus (table ) . this strongly implies a form of interference or protection from transmissibility that was provided by the cold-adapted virus. the results show that nibrg- and indo ⁄ viruses were able to spread between cages over the m distance ( % and % naïve animals were successfully infected, respectively). a ⁄ california ⁄ ⁄ influenza and vn viruses did not transmit between infected and non-infected guinea pigs housed in separated cages (table ) . pigs with confirmed a ⁄ california ⁄ ⁄ virus replication were also infected with nibrg- virus if h n -and h n -infected animals were separated by a space. thus, influenza virus transmission from h n -to h n -infected pigs has been shown, but the reverse pattern did not occur. transmission of nibrg- or a ⁄ california ⁄ ⁄ viruses was not observed when contact pigs were first vaccinated with the mdv and housed at a m distance ( table ) . it was also shown that efficiency of transmission of nibrg- was much higher than of other studied h n viruses; it can be transmitted between naïve guinea pigs separated from infected animals at a distance of - m (data not shown). five reassortants were isolated from animals which were infected with a ⁄ california ⁄ ⁄ virus and co-caged with pigs inoculated with nibrg- . two reassortants possessed different combinations of pr , nibrg- , and a ⁄ california ⁄ ⁄ genes and demonstrated the non-ca ⁄ non-ts phenotype typical of wt viruses. unexpectedly, two other reassortants inherited ha gene from nibrg- , na gene from a ⁄ california ⁄ ⁄ , and other genes from pr became ca and ts. : non-ts reassortant inherited pa gene from pr and seven other genes from a ⁄ california ⁄ ⁄ , gained ca properties. in spite of aforesaid experimental data, we cannot exclude the theoretical possibility of simultaneous infection of human host with cold-adapted and wt influenza viruses. to better understand possible consequences of such a reassortment event, we co-infected guinea pigs with a mixture of mdv and nibrg- viruses. nasal washes were collected and cloned by limited dilutions in hen eggs in the presence or absence of immune serum to the mdv. cloning of nasal washes without antiserum led to isolation of over clones, which were all identical to the mdv (data not shown). when nasal washes were cloned in the presence of antiserum, only nine clones were isolated. genome composition analysis showed that all isolates were triple reassortants, which had inherited pb and na genes from mdv, pa gene from pr , and ha gene from nibrg- . the origin of the other gene segments (pb , np, m, ns) in the genome of guinea pig-derived reassortants varied. reassuringly, all reassortants generated in vivo had the phenotype typical of the mdv. the severity of influenza outbreaks is partly determined by efficient spreading of the causative virus strain between human hosts. however, little is known about mechanisms underlying influenza virus transmission in humans. guinea pigs have been shown to be a suitable model for influenza transmission studies. our in vivo study showed that influenza a viruses vary in their transmissibility. nib-rg- and indo ⁄ viruses were able to transmit to naïve animals caged distantly from infected animals. in contrast, cold-adapted viruses, the same as those used for licensed laivs, showed no signs of transmission from one guinea pig to another. our study also provided evidence of a lower level of transmissibility of the novel pandemic h n virus compared to the nibrg- and indo ⁄ h n strains evaluated. benefits of vaccination with laiv to aid in the control of influenza outbreaks are acknowledged by the who. in our study, the mdv inoculated into guinea pigs appeared to interfere with and even offer protection from transmission of the highly transmissible nibrg- virus. the ability to immunize with the laiv and subsequently block the spread of a homologous h n subtype and a heterologous h n subtype influenza virus between guinea pigs has been shown. interference between cold-adapted and wildtype influenza virus infection was the most likely explanation for the data observed in our study. the mdv inoculated into guinea pigs might in some way interfere with transmission of highly transmissible influenza viruses. it is believed by some that widespread use of laiv could increase the potential risk of reassortment of the vaccine strain with circulating influenza viruses immediately following vaccination. however, it was shown that any such potential reassortments would most likely lead to yet attenuated viruses. our in vivo studies have shown that introduction of mdv genes into the genome of nib-rg- virus led to the generation of triple reassortants inherited pb and na genes of mdv and ha gene of h n virus. all isolates possessed phenotypical markers associated with attenuation of mdv. our data suggest that even if a reassortment event of such rare occurrence between a laiv strain and a circulating virus were to occur, it would most likely lead to a reassortant that would retain highly attenuated phenotypic properties of the vaccine strain. our data strongly support the safety of laivs, especially those developed against highly transmissible h n and h n pandemic influenza viruses. this information builds upon databases that have clearly shown the low likelihood of transmitting an laiv, as well as the high likelihood of any field reassortment of laiv with a circulating influenza virus to retain important properties of the cold-adapted, temperature-sensitive vaccine master composition. very interestingly, we also present data that show the potential of a laiv to prevent the transmission of highly infectious influenza viruses, perhaps identifying a broader role for laiv in the overall scheme of influenza virus prophylactic use. background: schlieren imaging is a non-invasive, real-time airflow visualization technique that relies on differences in air temperatures (and the resulting changes in the refractive index) to allow exhaled human airflows to be seen clearly against the background of more-stationary, ambient air. recently, this technique, well-known to engineers, has been applied to better understand and characterize airflow behaviors associated with everyday, as well as healthcarerelated, human respiratory activities. materials and methods: as a surrogate marker for the behavior of airborne infectious agents, schlieren imaging was used to visualize the airflow patterns produced by adult human volunteers of different ages while coughing with and without the wearing of standard surgical and n masks. results: the cough plumes were generally similar in shape and range for all the adult volunteers used in this study. although both the surgical and n masks decelerated and blocked some of the forward momentum of the coughed airflows, much of the cough plume was redirected and escaped around the top, bottom, and side edges of the masks to merge with the volunteer's natural, verticallymoving thermal plume. conclusions: schlieren imaging is a safe technique for visualizing exhaled airflows from human volunteers without the need for potentially-irritant or toxic particle tracers. findings from these schlieren imaging experiments will assist the development of more effective aerosol infection control guidelines in healthcare premises where patients infected with potentially airborne infectious agents (e.g., influenza and tuberculosis) are present. these infectious agents may be transmitted to healthcare workers, other patients, and their visitors by way of exhaled airflows. with the recent influenza pandemic , and the ongoing concerns about human cases of avian influenza h n infections, there is now a very real concern about the potential for the aerosol transmission of respiratory pathogens. such concerns amongst staff and patients in healthcare environments have led to a greater emphasis on the understanding and control of infectious airflows. , previous visualization techniques have used potentially-toxic or irritant gas or particulate tracers with hazardous laser light sources that have precluded the use of human volunteers as subjects. instead, various forms of lung models that simulate human respiratory patterns with such particulate tracers have been used. , schlieren imaging is a technique familiar to engineers and offers a non-invasive (i.e., no tracer required) airflow visualization method that depends only on differences in the refractive index of the warmer, human-exhaled air and the cooler ambient air. the use of a simple incandescent or light-emitting diode (i.e., non-laser) light source is safe and allows human volunteers to be used as experimental subjects, where their exhaled airflows are then observed using a large, precise spherical or parabolic telescopic mirror and a camera, and are recorded for later analysis and presentation. [ ] [ ] [ ] the analysis of these patterns of 'real-life' human airflows will be useful in optimizing aerosol infection control guidelines, which aim to reduce the transmission of airborne infectious agents to other healthcare personnel, patients, or their visitors. the images and analysis presented here have all been obtained from the large m diameter parabolic mirror (figure ) situated at the gas dynamics laboratory of penn state (directed by gary s. settles). this large schlie-ren imaging system has been in use for over years to obtain high quality schlieren images for various engineering applications. it has only recently been applied to clinically-relevant imaging. the objective of this paper is to augment and expand upon the details of the methods and results presented in an earlier study using this same schlieren imaging system. the aim of this series of studies is to visualize and capture a series of airflow images produced by coughing from adult human volunteers of different ages ( - years old). these included males (three of years, one of years of age) and females (one of years, one of - years, and one of - years of age). each volunteer was tested with and without wearing either a standard surgical mask or n mask. more specifically, the aim was to visualize the extent and direction of leakage around the mask whilst each subject was coughing. penn state institutional approval for experiments involving human subjects was also obtained. each volunteer was asked to stand approximately m in front of the schlieren mirror, facing across the surface of the mirror on one side, and to cough several times as the real-time, color image and video footage was recorded by the operator (using a nikon d camera; nikon inc. melville, ny, usa). this process was repeated whilst each volunteer was wearing a standard surgical mask then an n mask (supplied by mÔ, st paul, mn, usa). some of the schlieren images obtained from some of these volunteers have been published previously: for a -year old male, the year-old female and a -year old male, and the - year-old female. this article completes this series of schlieren images obtained from these experiments by including the images recorded for the older, year-old man. generally, it was found that the shape of the cough plumes (shown in the figure as darker shadows emanating from the subject's mouth) produced by adult humans of different ages was relatively similar. cough plumes are roughly conical in shape and very turbulent, usually passing beyond the extent of the m mirror (figure a) . a previous detailed study of one of these images measured a maximum airflow velocity of m ⁄ second for an adult cough. similarly, the effects of wearing surgical and n masks can be generalized across different ages. wearing a surgical mask allows leakage of the coughed air from the sides, top, and bottom of the mask ( figure b ). there is also some leakage through the mask, as indicated by the darker patches of air directly in front of the mask ( figure b, c) . the useful effect of the mask appears to be a deceleration and redirection of this coughed (and potentially infectious) air into the natural, upward-rising human thermal plume, which captures it and carries it upwards where it is diluted and less likely to transmit infection to others. the effects of the n mask are similar (i.e., deceleration and redirection), yet due to its tighter (mask-fitted) face seal, more of the coughed air appears to penetrate the front of the mask ( figure c ). this penetrating air is, however, also decelerated sufficiently to allow the wearer's natural thermal plume to carry it upwards. , discussion from these series of schlieren images presented in this and other related studies, [ ] [ ] [ ] it is clear that schlieren imaging offers a safe, non-invasive, real-time technique to visualize human exhaled airflows for all age groups. it is apparent that, at least where airflow patterns are an acceptable surrogate marker for airborne transmission risks, there are beneficial effects of wearing either type of mask, even when the mask fit is relatively poor. this is often the case when n -style masks are purchased and used by the general public -in contrast to the situation with healthcare workers, who are often accurately fit-tested for this type of mask. the immediate significance of this can be seen when masks are bought by parents for their children. often, these will not be of pediatric size and the mask-fit will be loose. children are well-known to be major sources of infection in the community because of their relatively poor immunity to many types of infectious agents due to their young age and, therefore, limited past-exposure history. these images allow infection control teams to literally see how far and how fast potentially-infectious human exhaled airflows can travel from an individual. this may have significant implications for guidance on the wearing of masks for infected staff and patients, on ward bed-spacing, as well as for the types of masks to be used in different situations. the important practical potential lies in the non-intrusive visualization of airflows associated with human volunteers, to assist in heightening the awareness amongst healthcare workers of the risks and potential for the airborne transmission of infectious agents, as well as the development of more effective aerosol infection control policies. schlieren images can be analysed more quantitatively, e.g., with the 'schlieren-piv' technique, , though this additional quantitative data is probably more of research interest than being of immediate practical use to everyday hospital infection control teams. these are the subtypes that we have studied. clearly, the question arises as to whether the changes in antigenicity are coupled with changes in germicide susceptibility. we have employed a modified log-reduction method in a cell culture system employing mdck cells in serum-free ex-cellÔ medium supplemented with trypsin. microscopic examination of cpe was the marker for infectivity together with plaque assay. we confirmed antiviral potency by using specific subtype influenza identification subtype technology, quidel quickvue Ò influenza a + b test. the log inactivation and percent inactivation by bac after a second contact time for the h , h , and h pandemic strains are as follows: a ⁄ swine ⁄ iowa ⁄ ⁄ h n , ae log ⁄ ae %; a ⁄ swine ⁄ cal ⁄ h n , ae logs ⁄ ae %; a ⁄ j ⁄ ⁄ h n , logs ⁄ ae %; and a ⁄ hong kong ⁄ h n , ae logs ⁄ ae % (table ). comparable results of antiviral efficacy are obtained with the tcid and plaque assays against all subtypes studied. when performing the plaque assay the sensitivity of virus recovery was better in the vessel with a larger surface area and overall recovery was in agreement with the potency determined by tcid assay. in our plaque assay, we inoculated a ⁄ hong kong ⁄ ⁄ virus dilutions into two different vessels with hours adsorption time: -well plate and t- flask, ml inoculum per replicate. virus titers obtained were: ae · pfu ⁄ ml from -well plate and ae · pfu ⁄ ml from t- flask ( table ). the discrepancy on virus potency can possibly be explained as: the binding of virus to host cell occurs only when virus gets a chance to interact with the cell on the monolayer during adsorption time. the percentage of virus population in the inoculum that has the opportunity to bind to the cell mainly depends on the surface area where this interaction takes place. therefore, in our experiment the plaque assay in the t- flask gave higher virus recovery ae versus ae · pfu ⁄ ml. the increased virus recovery can translate into better sensitivity of the test system for disinfectant and antiviral agents. the potency of the virus used in this study was determined by tcid was · tcid ⁄ ml. rapid diagnostic testing for influenza (quickvue Ò influenza a + b test, quidel) for aj versus bac was studied. the presence of influenza viral nucleoprotein a determined by quickvue kit correlated % with the viral infection based on by cpe in viral culture. interestingly, the inactivation of viral nucleoprotein was able to be revealed with diagnostic kit in the dilutions of virus ⁄ bac reaction mixture, which possessed prominent cytotoxic effect for the host cells in viral culture system. this type of molecular testing method is useful for interpreting antiviral efficacy against a background of cytotoxicity. these experiments are intended for the sponsor to substantiate to us fda that their antiviral substances are safe and effective. the data shows that the three hemagglutinin subtypes were highly susceptible to the quaternary ammonium compound in the short term in vitro experiment. the appearance of novel subtypes in the future can be met with the assurance that disinfectant and ⁄ or antiseptic resistance will be unlikely. certainly, from the above data, although genetic reassortment of human and swine viruses may modulate influenza pathogenesis and limit existing vaccine benefit, it is not likely be a factor in control of viruses on environmental surfaces by benzalkonium-type disinfectant ⁄ cleaning agents in community or health care environments. table . comparison of viral titer obtained in different vessels using quantal tcid and plaque assay methods plaque assay tcid assay t- ( cm ) -well plate ( cm ) tcid ⁄ ml tcid ⁄ ml ae · pfu ⁄ ml ae · pfu ⁄ ml · ae · options for the control of influenza vii outbreak influenza in aged care facilities (acfs) is associated with an increased risk of poor health outcomes among residents, including death. in this paper we share our experience of managing an outbreak of viral respiratory infection in an acf very early in the influenza pandemic and also describe some of the emerging issues relating to crossreacting antibodies to the pandemic (h n ) influenza virus in the very elderly. the outbreak investigation was conducted as part of an urgent public health intervention initiated by the new south wales (nsw) department of health during the early stages of the first southern hemisphere wave of the pandemic. nose and throat swabs for nucleic acid testing (nat) plus acute and convalescent serum samples ( weeks apart) were collected from all the residents of an acf where an influenza-like illness (ili) outbreak occurred. the investigation revealed dual outbreaks of pandemic (h n ) influenza and rhinovirus infection. out of residents, three had laboratory confirmed influenza [two with pandemic (h n ) ], and had rhinovirus infection on nat. testing of acute sera collected from every subject found elevated ( ‡ : ) pandemic (h n ) hai antibody in % ( ⁄ ) subjects aged years or more (born before and median age years; geometric mean titre-gmt ae ) compared with none of the residents aged under years (born after and median age years; gmt ae , p = ae ). the acf was closed to visi-tors for days. the symptomatic residents received treatment-dose oseltamivir, and all other residents were given oseltamivir prophylaxis. more than one virus may be circulating in an acf with an ili outbreak at any one time in winter. a significant proportion of elderly residents had pre-existing cross reacting antibody to the pandemic (h n ) , which may explain the minimal clinical impact of pandemic (h n ) in this elderly population. influenza is one of the leading causes of infectious death in elderly people, principally due to co-morbidities and declining immune competence with age. it is the most important agent in outbreaks of respiratory illness. influenza in aged care facilities (acfs) is associated with an increased risk of poor health outcomes among residents, including death. the clinical presentation of influenza in residents of acfs can be subtle, with a blunted febrile response and a non-specific decline in mental and functional status. residents commonly have underlying diseases that can be exacerbated by influenza infection, and in addition, they are at higher risk of serious influenza-related complications than community dwelling elderly people. people aged over years are also at higher risk of influenza-related death, and more than % of annual influenza-related mortality is usually confined to this high risk group. in australia, influenza and pneumonia have sub-stantial health impacts; recorded as being the underlying causes of death for persons in . since the world health organization declared an influenza pandemic in june , australia has suffered one of the highest rates of confirmed infection during the first southern hemisphere wave. by late october there were reported deaths due to pandemic influenza in australia, and to date there have been about deaths reported worldwide. although disproportionately far fewer elderly people developed clinical influenza during the current pandemic than occurs with seasonal influenza, their case-fatality rate remained substantial. early in the pandemic (june ), we investigated a suspected pandemic influenza outbreak in a rural acf in the state of nsw, australia. the epidemiology (including virulence and clinical outcome in the elderly) of the pandemic (h n ) virus was mostly unknown at the time of investigation, and as time passed, this investigation provided clarity on some important issues of the influenza epidemiology in the elderly population. in this paper we share our experience of managing a dual outbreak of viral respiratory infections early in the pandemic, and also describe some of the emerging issues relating to the cross-reacting antibodies to pandemic influenza in the very elderly. the outbreak investigation was conducted as part of urgent public health intervention initiated by the nsw department of heath in conjunction with the local public health unit, the national centre for immunisation research and surveillance (ncirs), and the institute of clinical pathology and medical research (a who national influenza centre). to determine the extent and cause of the outbreak, a public health research doctor (gk) was dispatched from sydney over a weekend to assist with outbreak investigation and control. on june th , the greater southern public health unit surveillance officer (bd) received a report of a possible pandemic (h n ) outbreak in a local acf. on investigation, it was discovered that days earlier a year old female resident had become generally unwell, but without specific symptoms of influenza like illness (ili). soon after, nine of the co-residents (but no staff) had developed symptoms suggestive of influenza. one other resident had returned from a melbourne (victoria) hospital (where pandemic (h n ) was known to be circulating) the previous week after surgery, but did not have ili symptoms. on june th, the symptomatic residents had nasal swabs taken by the local doctor for influenza [including pandemic (h n ) ] nucleic acid testing (nat). there was rising concern due to reports of widespread pandemic (h n ) influenza in a local army camp just over the border in nearby victoria, where pandemic (h n ) influenza was known to be circulating widely. on june th, the year old lady proved nat positive for pandemic (h n ) , but none of the other samples were pandemic (h n ) nat positive. concern arose that there might be an outbreak of pandemic (h n ) in the facility, and that some of the swabs from other residents might be false negatives. between and june, after consent was obtained, directly or through next of kin in demented residents, all submitted to venipuncture for serology, successfully, and the other as yet un-swabbed residents were swabbed. basic demographic data were collected from every resident with clinical information on co-morbidities and current medication use. convalescent blood samples were collected after weeks on th july from of the residents. swabs were sent to icpmr where nat for influenza a [including pandemic (h n ) ] and b was performed. the acute and convalescent serum samples were tested later (in december ), using haemagglutination inhibition assay (hai) to detect pandemic (h n ) antibody. , interventions the acf was closed to visitors from th until th june. treatment of the positive case and the nine symptomatic residents, with twice daily oseltamivir, was begun on saturday june th, and all other residents were started on once daily oseltamivir prophylaxis. the facility manager and local general practitioner (gp) monitored patient health on a daily basis, and none had to stop oseltamivir due to adverse events. one resident with ili who was known to have moderately impaired renal function was given once daily rather than twice daily oseltamivir treatment. the age range of the residents was - years with a median of years. all residents had underlying medical conditions, e.g., chronic cardiac and respiratory diseases ( table ) testing of acute sera collected from every subject found elevated ( ‡ : ) cross-reacting hai antibody to the pandemic (h n ) in % ( ⁄ ) of subjects aged years or more (born before and median age years; geometric mean titre-gmt ae ). however, the hai titre was consistently < : and significantly lower (gmt ae , p = ae ) in the residents aged under years (range - years, median years) (figure ). the index case (nat positive) did not show a significant raise in hai level in convalescence (going from to ). the pandemic (h n ) case that was determined by serology was pandemic (h n ) nat negative. to our surprise, seven of the other asymptomatic residents had rhinovirus detected on extended nat (reported on june th), despite being asymptomatic at time of swabbing and remaining so. the original nine influenza nat negative samples were then tested and three of these were also nat positive for rhinovirus; in total, ten proved nat positive for rhinovirus ( ae %). the serologically confirmed pandemic (h n ) case was also positive for rhinovirus infection. of interest was that only one resident had a documented fever. this investigation illustrates some of the difficulties in managing and investigating possible influenza outbreaks in real time in the context of an influenza pandemic. finding a nat positive case of pandemic (h n ) influenza among many other symptomatic cases raised the possibility (although not the probability) that pandemic (h n ) was the cause of the outbreak. rhinovirus infection, however, was confirmed by nat in ten residents. this outbreak illustrates that more than one virus (in this case and perhaps ) may be circulating in an acf at any one time in winter. in ili outbreaks in acfs, broad laboratory testing is recommended; nat is the most sensitive method of detecting influenza or other viruses in respiratory tract samples. studies have found that the pandemic (h n ) haemagglutinin (ha) gene is more closely related phylogenetically to the h n virus and classical swine influenza a ⁄ h n viruses than more recent seasonal human influenza a ⁄ h n viruses. it is antigenically similar to the h n pandemic virus in terms of the immunodominant antibody response to haemagglutinin. [ ] [ ] [ ] it is likely that individuals alive during the emergence and initial persistence of the pandemic virus would have higher levels of cross-reacting hai antibodies to the pandemic (h n ) , which would contribute towards better clinical protection. in our investigation, % of the residents born before (aged years or above in ) had pre-existing cross-reacting hai antibody to the pandemic (h n ) . in elderly populations, severe illness may be associated with organisms typically considered to be mild, such as rhinovirus. however, studies have shown that nursing home residents may be susceptible to outbreaks of rhinovirus that may cause mild to severe respiratory illness, particularly in those with a history of lung disease. one rhinovirus outbreak in a nursing home in the usa caused fatalities. another outbreak showed residents with underlying lung disease are more likely to have longer infection, require antibiotics, develop bronchospasm, and have difficulty breathing; two residents with underlying lung disease required emergency treatment and one died. a previous influenza outbreak in a nsw aged care facility in caused significant mortality and morbidity. that outbreak resulted in hospital admissions and six deaths. in our investigation we have found that % of the residents had chronic lung disease and % had chronic cardiac conditions both considered as high risk for severe complications of both rhinovirus and influenza infection. however, there were no hospitalisations or deaths in our outbreak investigation. indeed only one resident developed fever, indicating that non-specific signs of illness (such as in our index case) may be the only, or early, indication of an ili. our own experience with managing other ili outbreaks has also taught us that staff of acfs may not be vigilant enough to detect fevers. in this outbreak, the nursing home staff, local gp, public health unit and the outbreak investigation team and supporting laboratory staff acted quickly and in a coordinated way. pre-existing cross-reacting antibody in the very elderly (aged ‡ years) probably helped to limit the spread of the pandemic virus (compared to the circulation of rhinovirus) within the acf. exposure to the pandemic (or a close variant occurring before ) appears to be responsible for a high hai titre in the very elderly, which contributed towards better clinical protection. however, wider testing early on would have alerted us more quickly to the main cause of the outbreak. treatment and prophylactic use of oseltamivir may also have contributed to halting the spread of pandemic (h n ) and also to symptom relief. pandemic (h n ) influenza virus (ah pdm) has spread worldwide since march . in a paper of ah pdm, % of infected individuals have experienced gastrointestinal symptoms such as diarrhea and vomiting, which is higher than that of seasonal influenza. however, little is known whether viable virus shed from stool and replication of viruses are ongoing in the gastrointestinal tract. , viral load and isolation of ah pdm in cell culture in stool samples has been reported. stool specimens were collected from patients suspected to have pandemic (h n ) infection from november through may . virus isolation was conducted in cell culture by using madin-darby canine kidney (mdck) cells and taqman based rt-pcr from % (w ⁄ v) stool suspension in phosphate-buffered saline. taqman based rt-pcr was conducted by using primers, probes, and positive controls provided by niid (national institute of infectious diseases of japan). to confirm presence of ah pdm viral rna, lamp (loop-mediated isothermal amplification) was used as supplemental testing. of patients, one child (case ) submitted one nasal swab and four stool samples, another one nasal swab and two stool samples, and the other one stool sample. informed consent was obtained. strand specific rt-nested pcr was performed for only case by using only one primer at the rt reaction and also assayed neu aca - gal and neu aca - gal binding specificity about isolated strain derived from nasal swab and stool. receptor binding specificity was performed using a solid-phase binding assay with the sialylglycopolymers (poly a-l-glutamic acid backbones containing neu aca - galb - glcnacb-pap or neu aca - galb - glcnacb-pap bond as described. ) nucleotide sequences of the ha gene of ah pdm viruses isolated from stool sample and nasal swab were analysed. in order to exclude the possibility of contamination, the stool samples and nasal swabs were subjected to virus isolation separately. after getting the results on the nucleotide sequence, we also confirmed no strain harboring identical sequence was isolated in our laboratory before and after the day of sample collection. ah pdm viral rna was detected in nine ( %) of the subjects from stool samples. among nine subjects, one case (case no. ) was positive for viral isolation. case , a healthy -year-old girl, experienced fever and abdominal pain, and the others had gastrointestinal symptoms without upper respiratory symptoms. in case , influenza a virus was diagnosed by rapid antigen test on the day of symptom onset. viable ah pdm virus was isolated from the stool sample and nasal swab on the second day from onset using mdck cells (table ). viral load decreased gradually after symptom onset. however, viral shedding was still present days after symptom onset. positive stranded rna was detected days after symptom onset from the stool specimen ( figure ). above two ah pdm strains (isolated from nasal swab and stool specimen) bound exclusively to human type receptor, neu aca - gal. sequence analysis demonstrated that isolated virus from stool samples was identical with that from nasal swabs in comparison of ha gene ( bp). ah pdm influenza virus was isolated from the stool and nasal swab samples in the same patient simultaneously by using mdck cells. our results suggests the detection of viral rna and viable ah pdm influenza virus from stool samples may serve as a potential mode of transmission and has important implications in understanding the context of ah pdm influenza virus. strategies to prevent transmission of influenza include use of respirators. ffp and n respirators are certified to fil-ter at least % of particles ( ae lm in diameter), and many guidelines have recommended that healthcare workers wear respirators in certain healthcare settings to protect against infection from patients with pandemic influenza. [ ] [ ] [ ] we have developed a proprietary acid-polymer formulation to coat a standard ffp respirator with an antiviral layer. we aimed to test this coated respirator for antiviral efficacy against a range of influenza viruses. a series of tests compared the antiviral efficacy of coated and uncoated respirators in conditions designed to simulate real-life exposure to influenza by varying the route of inoculation, contact time, temperature, humidity, moisture, and contaminating substances. we also investigated whether infectious viruses could be transferred from contaminated respirator surfaces to gloves. we tested human, swine, and avian influenza viruses, including influenza a and b viruses. influenza a subtypes were the a ⁄ h n pandemic strain, seasonal h n , h n , h n , h n , and h n . in each test, suspensions of influenza viruses were prepared to - log tcid ⁄ ml in mem. in some tests, organic contaminants (yeast, bsa, and mucin) were added. one set of respirators was maintained at °c and % relative humidity for hours before the viral challenge, and repeatedly sprayed with he-pes buffer to simulate respiratory secretions. for each test, three coated (glaxosmithkline actiprotect) and three uncoated (sperian willson easy fit) ffp respirator samples were inoculated with ae ml of a viral suspension, which was applied with a pipette, sprayed, or aerosolised to create airborne droplets. after minute at room temperature (on a shaker), the respirator samples were assayed for the presence of infectious viruses using standard methods. in one test, after a minute contact time of the respirator with the virus, nitrile gloves were applied with light pressure to the outer surface of inoculated respirator samples and then assayed after minute. samples were put into test medium (mem, supplemented with antibiotics [penicillin, gentamycin, or streptomycin] and amphotericin b or l-glutamine). the supernatants were vortexed, extracted, and used to prepare serial -fold dilutions in mem. each dilution was used to inoculate four wells of rmk cells in a multi-well plate, and these cultures were incubated and scored over days for cytopathic effects, cytotoxicity, and viability. (some tests substituted mdck cells; others used inoculated embryonated chick eggs.) all tests included negative cell controls, cytotoxicity controls, and neutralisation controls. the spearman-karber formula was used to calculate viral loads as tcid or eid . antiviral efficacy was calculated from the difference between the geometric mean loads of influenza virus on the coated and uncoated respirators after minute of exposure. the viral loads applied to respirators in these experiments ranged from ae to ae log tcid , and were therefore high in comparison with respiratory secretions from infected patients at the peak of influenza symptoms (range - log tcid ). tables - show that the average viral loads detected on uncoated ffp respirator samples remained high in all conditions tested, ranging from ae to ae log tcid (or ae - ae log eid ). in contrast, the average viral load on coated respirators after minute of exposure ranged from below the limits of detection to £ ae log tcid ( ae log eid ). therefore, the relative antiviral efficacy of the coating ranged from ‡ ae to ae log . table shows that the relative antiviral efficacy of the coated mask remained high in simulated-use conditions such as organic contaminants and repeated saturation at high temperature and humidity. in the experiment to test transfer of viruses from respirators, the gloves applied to regular uncoated inoculated respirators had a viral load of ae log eid (table ) . by contrast, no viruses were detected on either the coated respirators or the gloves applied to them. the relative reduction in contamination was therefore ‡ ae log . ‡ ae log viral load with organic contaminants* ae ae ae log viral load after heat, moisture, and simulated secretions** ae ae ae log viral load transferred to glove** ae £ ae ‡ ae log eid *influenza subtype was a ⁄ h n , and strain was vnh n -pr ⁄ cdc-rg. **influenza subtype was a ⁄ h n , and the strain was hong kong ⁄ ⁄ . results are mean log tcid , unless specified otherwise. results are mean log tcid , unless specified otherwise, based on an infectivity assay in triplicate. limits of detection varied. * pandemic strains. **results are mean log eid , based on a haemagglutinin assay in duplicate. options for the control of influenza vii ª blackwell publishing ltd, influenza and other respiratory viruses, (suppl. ), - strategies to prevent transmission of influenza include use of respirators, and many guidelines have recommended that healthcare workers wear respirators in certain healthcare settings for protection against pandemic influenza. - ffp respirators are certified in europe to filter at least % of nacl particles ( ae lm in diameter), and ffp and ffp respirators must filter at least % and % of these particles, respectively. influenza a viruses are typically ae lm, and can be carried in aerosolised droplets smaller than lm in diameter, which can disperse widely, remain airborne for hours, and be inhaled deeply into the respiratory tract. we have developed an acid-polymer formulation to coat the outer layer of a standard ffp respirator, in order to provide antiviral activity on the outer surface. we compared this coated respirator against standard ffp , ffp , and ffp respirators for filtration of aerosolised influenza viruses. the aim was to simulate protection against infectious viruses in droplets released when infected people cough and sneeze, and during aerosol-generating procedures in healthcare settings. the first assay compared three samples of coated ffp respirators (glaxosmithkline actiprotect) with three ffp controls (sperian willson easy fit). for each test, suspensions of influenza a (h n ) at ae log tcid ⁄ ml in ae · minimum essential medium (mem) were aerosolised with a nebulizer. the airborne droplets were introduced into a sterile chamber upstream of a respirator sample for minutes, at a flow rate of ae l ⁄ minute. constant airflow was maintained for another minutes after exposure to the virus. then the collection dish in the downstream sieve sampler (anderson) was assayed for infectious viruses using standard techniques. briefly, serial dilutions of the collection medium (mem with % fbs, % gelatine, and % hepes, supplemented with antibiotics and amphotericin b) in mem + trypsin were used to inoculate madin-darby canine kidney epithelial (mdck) cells in quadruplicate in a multi-well plate. these cultures were then incubated and scored over - days for cytopathic effects, cytotoxicity, and viability. negative cell controls and cytotoxicity and neutralisation controls were also performed. the spearman-karber formula was used to calculate tcid . the second assay compared five samples of coated respirators with five ffp controls ( m ) and five ffp controls ( m ). a suspension of influenza a (h n ), at ae tcid ⁄ ml, was nebulized for minute and seconds into the aerosol chamber, at a flow rate of ae l ⁄ minute, followed by constant airflow for minutes after exposure to the virus. then the collection medium in the downstream chamber (as before, with % nahco ) was assayed as described above. initial viral loads in the first and second assays were ae and ae log tcid , respectively, and were therefore high in comparison with respiratory secretions from infected patients at the peak of their influenza symptoms (range - log t-cid ). table shows that the average viral load that passed through the uncoated ffp respirators in the first assay was ae log tcid . the average viral load that passed through the coated respirators was ae log tcid . therefore, for active filtration of viruses, the relative efficacy of the respirator with antiviral coating was ae log greater than the uncoated respirator. for surface inactivation, the relative antiviral efficacy of the coated respirator was ae log . in the second study, table shows that the average viral load that passed through the uncoated ffp respirators was ae log tcid . in contrast, ae log tcid passed through the coated ffp respirators. by comparison with the viral load when no respirator was present ( ae log tcid ), the ffp respirators reduced the viral load by ae log , and the coated ffp by ae log . therefore, for active filtration of viruses, the respirators with antiviral coating reduced the viral load by ae log more than the ffp respirators. in this second study, the average viral load that passed through the uncoated ffp respirators was also ae log tcid . by comparison with the viral load when no respirator was present ( ae log tcid ), the ffp respirators reduced the viral load by ae log . therefore, for active filtration of viruses, the respirators with antiviral coating reduced the viral load passing through the mask by ae log more than the ffp respirators. table also shows that the coated respirators reduced the infectious viruses remaining on the mask surfaces by ae log more than the ffp respirators, and ae log more than the ffp respirators. even with a very high viral challenge, the coated respirators prevented passage of at least an additional ae log infectious viruses, compared with uncoated respirators. large numbers of infectious virions passed through all uncoated respirators tested. ffp respirators were no more effective than ffp respirators at blocking airborne influenza viruses. based on these in-vitro results, respirators with the antiviral coating could be expected to provide more protection than standard respirators from the risk of inhaling influenza viruses. strategies to prevent transmission of influenza include use of respiratory protection. ffp and n respirators are certified to filter at least % of nacl particles ( ae lm in diameter), and many guidelines have recommended that healthcare workers wear these respirators in certain healthcare settings to protect against infection from patients with pandemic influenza. , we have developed a proprietary acid-polymer formulation, designed to coat a standard respirator and inactivate influenza viruses on contact. we tested this coated respirator for cytotoxicity, skin irritation, and sensitisation potential. the antiviral coating was also tested for stability and leaching under extreme environmental conditions, such as physical abrasion and simulated breathing at different temperatures, levels of humidity and co , and saturation with contaminants. eight coated respirators were tested at standard relative humidity ( % rh) for hours, and one at elevated humidity ( % rh) for hours. four coated masks were treated with synthetic blood or oral secretions, and then tested at % rh for hour. the sample respirators were sealed onto a mannequin head inside an airtight chamber, and air at °c and ppm co was pumped through the masks by a cyclic breathing machine at l ⁄ minute. a mm glass-fibre filter was placed behind the respirator, over the mannequin's mouth opening. at the end of all tests, these filters were eluted and analysed using high-performance liquid chromatography (hplc). standard in vitro methods were used to assess the cytotoxicity of the coated polyester and uncoated polypropylene layers of the respirator (glaxosmithkline actiprotect). samples were extracted in minimum essential medium (mem), supplemented with serum, penicillin, streptomycin, amphotericin b, and l-glutamine, at °c for hours. triplicate monolayers of mouse fibroblast cells (l- ) were dosed with each extract (including a reagent control and negative and positive controls), and incubated at °c in % co for hours. after hours of incubation with samples or controls, the monolayers of mouse fibroblast cells were examined microscopically for abnormal cell morphology or cellular degeneration. samples of the coated respirator (comprising four polypropylene layers bonded to the coated polyester outer layer) were applied under occlusive patch conditions to the skin of adults. controls, including individual layers, were applied in the same way. in a separate patch test, samples of the coated polyester outer layer and controls were applied under the same conditions to adults. after hours, test patches and controls were removed. sites were then scored for itching, erythema, oedema, epidermal damage, and papular response after and hours. the patches were applied three times a week for weeks. to evaluate sensitisation, test patches were applied - days later for hours at different sites to the original samples. after this challenge, skin was assessed and graded for sensitisation potential after and hours. table shows that no residues of the antiviral coating or degradation products were detected in the air that had passed through any of the eight respirators. cytotoxicity tests showed that the coated respirator material caused % cell lysis or toxicity, classified as slight reactivity (grade ), and that uncoated material caused no cell lysis or toxicity (grade ) ( table ) . results for positive and negative controls were severe reactivity and no reaction, respectively. from the results of the two human repeat-insult patch tests, neither the coated or uncoated layers nor the fullthickness respirator fabric caused irritation (including itching, erythema, edema, vesiculation, epidermal damage, papules, or reactions beyond the patch site) or sensitisation in any of the adult volunteers at any of the time points. based on these results, in conjunction with published data on acute and repeat-dose toxicity, mutagenicity, local irritation, dermal sensitisation, and inhalation safety for all components of the antiviral coating, the potential topical or inhalation exposure to the coated antiviral respirator does not pose a safety risk. the antiviral coating is durable and stable, and stays on the outer surface of the respirator, even in extreme environmental conditions. the coated respirator is non-irritating and non-sensitising. therefore, this respirator is considered to be well-tolerated and safe for its intended use. ies were funded by gsk consumer healthcare, and gsk investigators were involved in all stages of the study conduct and analysis. knowing how influenza virus is transmitted at home and in school is the key to preventing its spread. at the previous two meetings of this conference, , we introduced our study of household transmission of seasonal influenza and reported our conclusion that protracted survival of the virus even after treatment increases household transmission, and is a major factor in the transmission of the virus to infants. on the other hand, during the recent pandemic, many schoolchildren developed serious respiratory tract disorders, which again highlights the significance of schoolbased transmission of the disease. in this study, we compared transmission of a new influenza strain at home and in school with that of seasonal influenza and proposed countermeasures. the for the analysis of school-based transmission, the epidemic status of seasonal influenza in children at six elementary schools over the past two seasons ( - and - seasons) was compared with that of pdmh in children at two primary schools. using observational data of school-based transmission, we also constructed a model for influenza transmission , and evaluated the effects of factors that could affect influenza transmission (e.g., antibody prevalence, transmission rate, non-infectious latent period, infectious latent period, school closure) through the use of simulations. in this study, a diagnosis of influenza was confirmed by rapid influenza antigen detection kit. we previously reported the high sensitivity of the kits, - not only for seasonal influenza, but also for h n pandemic compared to virus isolation and pcr. serum antibody was not investigated. most of the index patients were treated with oseltamivir or zanamivir, and patients were treated with amatadine. no treatment was done for patients. no nai therapy was done as prophylaxis within the family. the incidence of households with an initial case patient who subsequently infected another member of the household was ae % ( of households) for seasonal influenza or ae % ( of households) for pdmh . thus, the household incidence of pdmh was lower than that of seasonal influenza. in addition, the percentage of family members in households who were infected by initial case patients (household transmission rate) was ae % ( of individuals) for seasonal influenza or ae % ( of individuals) for pdmh . thus, the household transmission rate was also lower for pdmh than that for seasonal influenza. effect of family size on household incidence and household transmission rate an analysis of the effect of family size on household incidence showed that, in families consisting of - individuals, the incidence of seasonal influenza in order of increasing family size was ae %, ae %, ae %, ae %, ae %, and ae %, respectively, and the incidence of pdmh was ae %, ae %, ae %, ae %, ae %, and ae %, respectively, indicating that household incidence tends to increase with increasing family size. in contrast, no definite relationship was noted between household transmission rate and family size. transmission rates for seasonal influenza in order of increasing family size were ae %, ae %, ae %, ae %, ae %, and ae %, respectively, or ae %, ae %, ae %, ae %, ae %, and ae %, respectively, for pdmh (shown in table ). effect of age cohort of initial case patient in household on household incidence and household transmission rate an analysis of the effect of the age cohort of the initial case patient in the household on household incidence and transmission rate showed that the household incidence of seasonal influenza in c , c , c , and c was ae % ( of households), ae % ( of households), ae % ( of households), ae % ( of households), and for m and f was ae % ( of households) and ae % ( of households), respectively. therefore, household incidence was the highest in c , followed by the parents. when the initial case patient was a child, the household incidence increased with decreasing patient age. in contrast, the household incidence of pdmh in c , c , c , and c was ae % ( of households), ae % ( of households), ae % ( of households), ae % ( of households), and for m and f was ae % ( of households) and ae % ( of households), respectively. therefore, household incidence was higher when the initial case patient was a parent, rather than a child. the household transmission rates for seasonal influenza from c to f were ae %, ae %, ae %, ae %, ae %, and ae %, respectively. therefore, as for household incidence, the highest rate ( ae %) was observed in c . the corresponding household transmission rates for pdmh were ae %, ae %, ae %, ae %, ae %, and ae %, respectively, with the highest transmission rates observed for infections from parents (shown in table ). if the rate of individuals with a secondary infection transmitted from the initial case patient in a household is presented as a percentage of the total number of affected individuals, the rates for seasonal influenza and pdmh were ae % ( of individuals) and ae % ( of individuals), respectively. therefore, the rate of individuals with a secondary infection was lower for pdmh than that for seasonal influenza. by age cohort, the corresponding rates of individuals for seasonal influenza in c , c , c , and c were ae % ( of individuals), ae % ( of individuals), ae % ( of individuals), ae % ( of individuals), and for m and f was ae % ( of individuals) and ae % ( of individuals), respectively. for pdmh , the corresponding rates in c , c , c , and c were ae % ( of individuals), ae % ( of individuals), ae % ( of individuals), ae % ( of individuals), and for m and f was ae % ( of individuals) and ae % ( of individuals), respectively. these findings indicate that, especially in the case of pdmh , most secondary infections in parents tend to be transmitted from another household member. the mean annual prevalence of seasonal influenza and the new influenza strain at the elementary schools for the two seasons was ae % and ae %, respectively, whereas the prevalence determined days after appearance of the first case in school was ae % and ae %, respectively. in the recent season at the same elementary schools, however, the prevalence was a high ae %. since the prevalence at days after the appearance of the first case in school was already ae %, these data show that the influenza virus spread quickly throughout the schools. at the schools with high transmission rates in the early period of the pandemic, new infections were confirmed even days after the school closure action was taken. these findings indicate that pdmh , the current influenza virus, has a long latent period during which it becomes infectious and spreads from infected individuals to numerous others in their vicinity. we constructed a model for influenza transmission in schools and estimated the time course of changes in the number of expected cases and the expected prevalence during the season. in this model, school children were divided into six groups depending on the stage of infection: uninfected period with no immunity, non-infectious latent period, infectious latent period, onset, post-onset infectious period, and immune period. it was assumed that schoolbased transmission occurred during the infectious latent period prior to onset and that no infections occurred during the post-onset infectious period because children were absent from school. due to the long latent period of pdmh , the distribution of the non-infectious latent period of pdmh was established as (day , day , day , day ) = ( %, %, %, %) and the distribution of the infectious period as (day , day , day ) = ( %, %, %). when simulations were performed under these conditions using the model for school-based transmission of influenza in which children from classes with an outbreak were kept at home for days, the time course of changes in the number of affected individuals actually observed and the time course of changes in the number of expected cases were determined. the expected prevalence under these conditions was %. to evaluate the effect of school closure, simulations were performed based on the assumption that children from affected classes were not kept at home for days. it was shown that there was an increase in the expected number of cases during the days corresponding to the period of actual school closure and that the expected prevalence increased to %. based on these findings, it was concluded that keeping children home from classes with an outbreak is an effective means of controlling the transmission of influenza in schools (shown in figure ). if the transmissibility of pdmh virus at home is estimated based on the speed of transmission and the degree to which pdmh is prevalent in schools, it would be expected that the household transmission of pdmh is also higher than that of seasonal influenza. in fact, the opposite is the case. this paradox can be explained in two ways. . the number of children aged or more and parents with pdmh influenza as a percentage of the total number of affected individuals is lower than those with seasonal influenza ( ae % versus ae %). further, although the number of parents with a secondary infection was high at home, the percentage of the total number of individuals with pdmh was a low ae % ( of individuals), compared to that for seasonal influenza ( ae % [ of individuals]). in other words, adults are less susceptible to pdmh infections and there was a correspondingly small number of affected individuals. therefore, it was considered that the transmission rate at home was lower than that at school for this reason. . the percentage of households with more than one affected individual within the same family was higher for pdmh at ae % ( of households) than for seasonal influenza at ae % ( of households). in the patients secondarily infected with pdmh , ae % of them showed symptoms of infection days or more after the onset in the first patient, suggesting that they were not infected at home, and the actual household transmission was ae % ( of households). therefore, although the prevalence was higher for pdmh , it seems that household transmission was lower because households with an affected individual implemented satisfactory control measures against infection. seasonal influenza differs greatly from pdmh influenza in its transmissibility at home and in school. in the household transmission of pdmh influenza, both the household incidence and household transmission rate of pdmh were low compared to those for seasonal influenza. although transmission of seasonal influenza from infants to parents was marked, in the case of pdmh , the reverse was true with transmission from parents to children being predomi-nant. it should be noted that household transmission in mothers was common in all eight seasons, suggesting the need to reconsider control measures against infection when nursing unwell family members. in the case of school-based transmission, pdmh was more prevalent than seasonal influenza, indicating that the virus spread quickly throughout the schools. this difference was attributed to the long infectious latent period when pdmh rapidly became rampant in the schools. an analysis of school-based transmission using a model for influenza transmission showed that, when % of the student population is infected, schools should be closed for five consecutive days in order to minimize the spread of the disease. the effectiveness of seasonal influenza vaccine in preventing pandemic and seasonal influenza infection: a randomized controlled trial introduction household transmission has been estimated to account for one-third of all influenza transmission, , and children are at high risk of spreading the disease. with reference to previous evidence, - some vaccine deployment strategies target children to prevent them from infection and transmitting influenza. nevertheless, few studies evaluated the effectiveness of vaccinating children in reducing household transmission. , during - , a pilot randomized controlled trial was conducted to investigate such effect by studying households with school age children randomized to receive trivalent inactivated seasonal influenza vaccine (tiv). the monovalent vaccine against pandemic influenza a (h n ) (ph n ) had yet been available until the end of the first wave. various conclusions have been made as to whether seasonal influenza vaccine might possibly protect against ph n . [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] we report findings on the effectiveness of tiv against ph n observed in our cohort. households were screened if they expressed interest after receiving invitation letters distributed via their children's school or an existing pediatric cohort study. to be eligible, the household had to include at least one child aged - years who was not allergic or hypersensitive to any of the tiv components. children known to have immunosuppressive conditions or other contraindications against tiv were also excluded. written consent and assent were obtained from participants aged above years and those aged - years, respectively. proxy written consent was obtained from legal guardians or parents for participants younger than years. ethical approval was obtained from the institutional review board of the university of hong kong. consented households were allocated to the tiv and placebo group (in ratio : ) according a code generated by block randomization with random block sizes of , , and . an independent nurse prepared . one child (study subjects) from each household in the tiv group received a single dose of tiv with one child from each household in the placebo group receiving a single dose of saline placebo. parents and legal guardians were asked to report any adverse reactions days following vaccination. all participants, study nurses, and other research staff were blinded to the allocation and administration of vaccine or placebo. the vaccine allocation sequence was only disclosed to the investigators at completion of the study. serum specimens were collected from subjects shortly before (november-december ), one month after vaccination (december -january ), and after the winter (april ) and summer influenza seasons (august-october ). serum specimens were obtained from household contacts at baseline and after the winter and summer influenza seasons. all household members recorded any fever ‡ . °c, chills, headache, sore throat, cough, presence of phlegm, coryza, or myalgia daily on a symptom diary. they were also invited to report to the study hotline immediately if they experienced at least of the above signs or symptoms. as a response, the study nurse would visit the households with any sick members and collect nose and throat swab from all household members. the households were also telephoned monthly or increased to fortnightly during influenza seasons to monitor for signs and symptoms and remind them to report to the hotline. supermarket or book vouchers (for children) were given to the households including us$ for each serum specimen collected, us$ . for each home visit, and us$ for completion of the study. serologically-indicated influenza infection was the primary outcome of this study. it was define as a ‡ fold rise in antibody titer within each influenza season. other study outcomes included rt-pcr confirmed influenza virus infection, acute respiratory illness (ari) (two of any of the above listed signs or symptoms), and influenza-like illness (ili) (fever ‡ . °c with cough or sore throat). antibody titers against the vaccine strains were obtained by testing each serum specimens by haemagluttination inhibition (hai). viral microneutralization (vn) using standard methods was found to be more sensitive than hai in detecting antibody response against a ⁄ california ⁄ ⁄ (h n ) in another study conducted by our group and was, therefore, used in this study. the sera was initially diluted at ⁄ and further tested in serial doubling dilutions. nose and throat swabs were tested by reverse transcription polymerase chain reaction (rt-pcr) for influenza a and b viruses. technical details of the laboratory methods have been reported elsewhere. , fisher's exact test and chi-squared tests were used to compare count data including occurrence of side effects, laboratory confirmed, and clinically defined influenza infections. wilcoxon signed-rank test were used to compare the serum antibody titers between groups. exact binomial method or the wald approximation was used to estimate % confidence intervals where appropriate. all analyses were carried out in r version . . (r development core team, vienna, austria). twenty-five primary and secondary schools in the district of the study clinic were invited to participate. to parents of three schools that agreed to take part and another study cohort, invitation letters were sent and households were enrolled. personal referrals were made from these parents to enroll additional households. among enrolled households, subject with history of epileptic seizure was assessed to be contra-indicated against receiving the vaccine. blood taking failed in another subject, and both of them withdrew from the study. eleven households did not complete the study. table shows subject and household contacts of the tiv and placebo group were similar in demographics and prior influenza vaccination history. antibody titers before vaccination were comparable between groups (data not shown). most study subjects who received tiv showed antibody titer ‡ against the vaccine strains month after receiving tiv, and the proportion was significantly higher than those who received placebo (a ⁄ h n % in tiv versus % in placebo group, p < . ; a ⁄ h n % versus %, p < . ; b % versus %, p = . ). none of the study subjects had antibody titer ‡ against ph n following receipt of seasonal tiv. no serious adverse reactions were reported, and only pain at injection sites was slightly higher in tiv group (data not shown). subjects who received tiv had lower rates of serologically confirmed seasonal influenza a(h n ) ( % versus %, p = . ), a(h n ) ( % versus %, p = . ) and b infection ( % versus %, p = . , although the differences were not statistically significant (table ) . study subjects had higher rate of serologically confirmed ph n infection ( % versus %, p = . ), yet it was not statistically significant. after adjusting for potential cross reactive antibody response, % of subjects in tiv versus % in placebo groups showed ph n infection confirmed by either serology or rt-pcr (p = . ). little differences were observed for rt-pcr confirmed infection, ari, and ili in results combining the winter and summer influenza seasons. during winter season when seasonal influenza predominated, study subjects who had received tiv showed a lower tendency to develop ili ( % versus %, p = . ) or ari ( % versus %, p = . ). an opposite tendency was seen (ili % versus %, p = . ; ari % versus %, p = . ) during summer when ph n predominated. however, these differences were not statistically significant. rates of ili in subjects infected with ph n did not differ statistical significantly between subject who received tiv and placebo ( % versus %, p = . ). the study was not powered to detect indirect benefits to household contacts of vaccines resulting from reduced household transmission. attack rates were found to be similar between household contacts of subjects received tiv and placebo (data not shown). to examine potential factors that might affect risk of laboratory confirmed ph n infection, a multivariable logistic regression model was fitted to study all subjects and their household contacts. younger participants aged below years were found to have a higher risk (< years or = . , % ci . , . ; - years or = . , % ci . , . , > or = . ). after adjusting for age, sex, and date of study completion, receipt of tiv for the - influenza season was not found to affect risk of ph n infection. however, participants who had laboratory confirmed seasonal influenza infection during the study period had % lower risk of ph n infection (infected with seasonal influenza or = . , % ci . , . ; not infected with seasonal influenza or = . ). as (see table s for winter and summer results separately). influenza-like illness (ili) defined as temperature ‡ . °c plus cough or sore throat; acute respiratory illness (ari) defined at least any two of fever ‡ . °c, chills, headache, sore throat, cough, presence of phlegm, nasal congestion, runny nose, muscle or joint pain. limited by the sample size, we were not able to differentiate between the protective effect of seasonal a(h n ) and a(h n ) infection against ph n . other details of the results from the study were published elsewhere. discussion a non-significantly higher rate of ph n infection was observed in study subjects who received tiv compared to placebo. results from a multivariable logistic regression suggested that such a pattern might be explained by more common seasonal influenza infection in placebo group prior to the pandemic, protecting the placebo group against ph n . seasonal influenza infection within - months observed in our study might have conferred better cross protection than tiv against ph n . this resembles similar previous findings on cross protection between influenza infections in human and animal studies. [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] however, the same phenomenon has not been observed in some studies on seasonal influenza vaccine against ph n . , , [ ] [ ] [ ] apart from differences in study design and vaccine used, we speculate that a short time interval between ph n and most recent seasonal influenza peak activities might be crucial for the phenomenon. hong kong is a subtropical area where the pandemic was preceded immediately by summer seasonal influenza circulation and a few months apart from the winter - influenza peak. if cross protection from seasonal influenza lasts for only a short period, it might have waned below partial cross protection from tiv over time from last seasonal influenza infection. the current study is limited by a small sample size, and further studies are required to confirm our hypothesis. while tiv is only effective against matching strains, a universal influenza vaccine could provide better protection against the ever evolving influenza viruses. introduction immunisation of healthy, as well as high risk, children has been the focus of much recent attention both in prevention of seasonal influenza and during the h n pandemic. detailed information on reactogenicity, particularly for newer vaccine formulations that include adjuvants, is limited. we recently reported results of a head-to-head comparison of two h n pandemic influenza vaccines in children in the uk. here we present new, detailed analyses of reactogenicity data from that study, which has important potential implications for future paediatric influenza vaccine development and use. we compared the safety, reactogenicity, and immunogenicity of two h n influenza vaccines, one as b (tocopherol based oil in water emulsion) adjuvanted egg culture derived split virion, the other non-adjuvanted cell culture derived whole virion, given as two dose schedules days apart, in a randomised, open label trial as previously reported. the study was age stratified ( months to under years & - years) to ensure adequate data in young children. age appropriate safety data (simplified for under year olds) were collected for days after each vaccine dose and serum was collected at enrolment & days after the second dose. nine hundred-thirty seven children received vaccines as per-protocol. when comparing the two vaccines, grade ( ‡ mm) local reactions were seen more frequently following the adjuvanted than the non-adjuvanted vaccine in both age groups, after both vaccine doses. in children over years old, ae % versus ae %, p < ae , after dose one; ae % versus ae %, p = ae , after dose two, in children under years old, ae % versus ae %, p = ae , after dose one (non significant, ns); ae % versus ae %, p < ae after dose two. fever ‡ °c (axillary measurement) was seen more frequently following the second dose of the adjuvanted vaccine compared to the non-adjuvanted vaccine in < year olds ( ae % versus ae %; p < ae ). looking specifically at the adjuvanted vaccine in under year olds, comparing the second dose with the first, there were significantly higher rates of fever ‡ °c (axillary measurement) ( ae % versus ae %, p < ae ), local grade ( ‡ mm) reactions ( ae % versus ae %, p = ae ), pain ( ae % versus ae , p = ae ), use of analgesia or antipyretic medication ( ae % versus ae %, p < ae ), and decreased activity ( ae % versus ae %, p < ae ). the adjuvanted vaccine was significantly more immunogenic, most notably in the younger children. in < year olds, haemagglutination inhibition (hi) seroconversion rates were ae % versus ae %, p < ae . among all general and local reactions measured, only the maximum temperature measured during the days after the second dose of the adjuvanted vaccine showed a significant (positive) association with post vaccination hi titres. for each °c rise in temperature there was a % increase in titre (p < ae ). these reactogenicity data demonstrate a step towards the future possibility of one-dose influenza immunisation programmes for young children associated with low rates of fever and other reactions. the occurrence of fever following adjuvanted vaccine, seen particularly after a second dose in younger children, was quantitatively associated with enhanced antibody titres. this association was not seen with unadjuvanted vaccine. this apparent difference between the relatedness of the pyrogenic and immunogenic effects of the two vaccines merits further investigation. novel adjuvants appear to have the potential to overcome the relatively poor immunogenicity previously experienced with inactivated influenza vaccines in infants and young children. however, careful adjustment may be needed to optimise the balance between high protection and acceptable reaction rates. tries causing sporadic human infections. vaccination has been used as an effective public health tool for influenza prophylaxis. the goal of this study was to evaluate live attenuated influenza vaccine (laiv) vaccine candidates for subtypes h and h . the attenuated phenotype of h and h laiv candidates has been proven in experiments in ovo and in vivo. in randomized clinical trials among adult volunteers, no significant adverse reactions attributable to the live vaccine occurred. our results indicate that pandemic laiv candidates were well tolerated and elicited serum, local, and cellular immune responses. the emergence and spread of highly pathogenic avian influenza h n viruses in avian populations and concurrent infections in humans since has prompted efforts to develop vaccines for use in the event of an influenza pandemic. in , the world faced a new h n pandemic. immunization with inactivated or live vaccines is the primary measure for preventing influenza. laivs appear to be safe and efficacious, and might possibly provide broader immune responses than inactivated vaccines. our study evaluated laiv pandemic candidates as part of the global influenza pandemic preparation project outlined by the who. capacity of the viruses to grow at optimum, low, and elevated temperatures (ca ⁄ ts phenotype) was evaluated by routine technique in embryonated hen eggs. laiv and placebo were supplied by microgen (irkutsk, russia). the monovalent laiv was produced from the pandemic vaccine candidates and formulated to contain and ae eid per dose ( ae ml) of a ⁄ ⁄ california ⁄ ⁄ and a ⁄ ⁄ duck ⁄ potsdam ⁄ ⁄ , respectively. the vaccine or placebo was administered intranasally with a single-use dosing nasal sprayer. two doses were given at an interval of days. one hundred-ninety healthy adults aged - years were randomly divided into groups to receive either pandemic vaccine candidates ( ) or placebo ( ) . subjects were informed about purposes and methods of the study and potential risks associated with participation. all participants had an hai antibody titer of £ : to a ⁄ california ⁄ ⁄ (h n ) pandemic virus. in all there were and vaccines and and participants who received placebo, and were further tested for immune responses to h n or h n pandemic vaccine, respectively. another participants vaccinated with h n laiv were children between to years old. before the children were vaccinated, their parents were advised about study and their consent was required before any child was enrolled. on the advice of the national ethics committee, we did not include a placebo group in this study. individuals were not enrolled if they had an acute illness or fever at the beginning of the study or a history of egg allergy. immune responses of subjects were assessed by routine hai test (evaluation of serum igg antibodies), elisa (evaluation of iga antibodies eluted from the nasal swabs into steril pbs), and cytokine flow cytometry assay (evaluation of virus-specific cd + cd + ifnc + and cd + cd + ifnc + peripheral blood mononuclear cells). the results of phenotypic analysis in ovo showed that pandemic vaccine candidates retained the cold adapted-temperature sensitive (ca ⁄ ts) phenotype, typical of the coldadapted parental mdv. in contrast and as expected, a ⁄ california ⁄ ⁄ and a ⁄ duck ⁄ potsdam ⁄ - parental strains had the non-ts ⁄ non-ca phenotype typical of wt viruses. the h n pandemic vaccine candidate demonstrated an attenuated phenotype in mice and in java macaques and did not infect chickens. the vaccine attenuation study confirmed the attenuated phenotype of a a ⁄ ⁄ california ⁄ ⁄ pandemic laiv candidate in mouse, ferret, and guinea pig models. the phase i ⁄ ii randomized, controlled, double-blind clinical study safety evaluation of pandemic vaccine candidates in adults clinical examination of subjects who received two doses of pandemic vaccine candidates indicated that both vaccines were well tolerated. no fever reactions were observed after the first or second vaccination. after the first vaccination, ae % and ae % of reactogenicity events consisting of catarrhal symptoms, such as pharyngeal irritation or hyperemia, were observed for h n and h n vaccine candidates, respectively. after revaccination, subjects did not report local or systemic reactions. to determine whether a serological response occurred in the cohort of immunologically naïve subjects vaccinated with pandemic vaccine candidates, hai and elisa tests were used (table ) . post-vaccination geometrical mean titers (gmt) among subjects who received two doses of h n vaccine were significantly higher than pre-vaccination titers. the frequency of ‡ fold antibody rises was significantly higher ( ae %) after revaccination than after one dose ( ae %). the percentage of subjects with post-vaccination serum hai titers to h n ‡ : was ae % and for titers ‡ : , it was ae %. no seroconversions in the placebo group were detected. the virus-specific nasal iga antibody response to vaccination after two doses of the h n vaccine candidate demonstrated significant increases of ‡ fold rise iga antibodies ( %) compared to one dose. cumulative data of h n vaccination (all applied tests) showed % and % of conversions after the first and the second vaccination, respectively. increasing h n vaccine virus infectivity from ae to ae eid ⁄ dose lead to an enhancement of post-vaccination hai titers in vaccinees after the first vaccination to homologous h n antigen from ae % to ae % of ‡ fold antibody rises. values of post-vaccination serum hai antibody titers in subjects vaccinated with another pandemic vaccine candidate, a ⁄ ⁄ california ⁄ ⁄ , also proved to be rather low. after the primary vaccination, the percentage of subjects with hai protective antibody titers ‡ : were ae %. after revaccination, this parameter increased to ae %. four-fold increases in serum hai antibody titres were four-fold conversions after the first and the second vaccination was ae % and ae %, respectively. elisa antibodies in nasal swabs showed had an advantage in detecting induction of local iga as compared to serum hai antibodies. after revaccination four-fold serum hai antibody conversions were ae % vs. ae % of iga conversions in nasal swabs, respectively. taking into account cumulative data of h n vaccination (hai and elisa data), the obtained results were here and in the ae % and ae % of conversions after the first and the second vaccination, respectively. fourty-seven subjects were vaccinated with h n laiv, and who received a placebo were chosen for evaluation of cellular immune response by cytokine assays. after revaccination, the mean increases of both cd + and cd + memory cells were significantly higher in vaccinated subjects compared to the placebo group. interestingly, the same effect of vaccination was observed in vaccinees without detectable conversions of hai antibody titers. even after a single vaccination, the rate of subjects with significant increases of these cells in the blood was ae % (cd + ) and % (cd + ). after the revaccination, the percentage of subjects with significant increases in cd + and in cd + cells was ae %. immunogenicity of h n pandemic vaccine candidate in children hai antibody results among children aged to years proved to be significantly higher when compared to adult subjects: after the first vaccination, ae % of the children seroconverted; after revaccination, seroconversions reached ae % ( table ). the gmt rise to h n vaccine with primary vaccination was : ; after revaccination it increased to : . benefits of vaccination with laiv to aid in the control of influenza outbreaks are acknowledged by the who. many years of laiv seasonal trials have shown excellent tolerability and low reactogenicity. [ ] [ ] [ ] indeed, data showed that live influenza vaccines cause minimal systemic, local, and thermal reactions, generally from to %. a different situation was observed in the cohort of immunologically naïve volunteers vaccinated with pandemic vaccines. the rate of local reactions to a ⁄ ⁄ california ⁄ ⁄ and a ⁄ ⁄ duck ⁄ potsdam ⁄ ⁄ vaccine candidates increased to ae % and ae %, respectively. after revaccination no significant local and systemic reactions were observed. this confirms, indirectly, the development of a sufficiently high level of protection after the first vaccination with pandemic laiv. the most important criterion for assessing the quality of vaccines is their estimated safety, epidemic effectiveness, and immunogenicity. however, current regulatory documentation mandates that induction of serum antibodies, measured by hai, as the only criterion for a laiv immunogenicity evaluation. in addition to the standard hai assay, we determined serum (igg) and local (iga) antibodies in adult subjects vaccinated with an h n pandemic vaccine candidate. evaluation of overall results obtained in these additional serological tests, as well as those from the hai assay, showed an immune response to the vaccine in the majority of subjects ( ae % of ab seroconversions after the single vaccination and ae % after revaccination, respectively). these data show that methods used to routinely measure laiv immunogenicity should be revised to include a number of additional immunological methods such as igg and iga elisa, and cytokine assays consistent with the recently updated who recommendations on laiv monitoring. these clinical studies clearly demonstrated that pandemic laiv candidates are effective at generating pandemic specific influenza immunity. a key finding from this study is that it may be practical to give the vaccine as a single dose to both children and adults. evaluation of our laiv pandemic vaccine candidates was performed as part of the global influenza pandemic preparation project outlined by the who. it was considered that laiv could be produced in greater quantities and more rapidly than inactivated vaccines. together with the generation of herd immunity by laiv, this suggests that laiv implementation during the first wave of a pandemic may provide significant social, economic, and health benefits to the community. authors are thankful to path for the financial support of h n pandemic vaccine study. we are grateful for the the main evolutionary mechanism of influenza viruses during inter-pandemic period is the antigenic drift, but the epidemiological picture of circulating viruses is complicated by a high level of heterogeneity of strains, even though drift does not occur, due to co-circulation of drifted and old strains or to co-circulation of viruses belonging to the same type ⁄ subtype but with different antigenic patterns. [ ] [ ] [ ] [ ] [ ] [ ] lack of data exists on the impact of the wide heterogeneity of circulating strains on the seroprotection and on-field effectiveness of influenza vaccine: in particular, little is known about the ability of influenza vaccine to elicit an effective immune response against isolates with few amino acid mutations with respect to vaccine strains that represent the majority of circulating viruses. mf -adjuvanted vaccines, which are currently used for the prevention of seasonal influenza epidemics in elderly, are showed to confer higher seroprotection against homologous and drifted a(h n ) strains than non-adjuvanted vaccines. [ ] [ ] [ ] the broader immune response showed by mf -adjuvanted vaccine was measured using hi and nt assays against egg-grown drifted strains representing vaccine composition changes during the following seasons, but its ability to elicit a broader immune response against circulating viruses belonging to vaccine cluster and presenting amino acid mutations onto antigenic sites or against on-field isolates not-antigenically distant from vaccine strains has not yet been investigated. showing amino acid changes onto antigenic sites in position (n k), (n k), and (p s) with respect to a ⁄ california ⁄ ⁄ . in particular, a ⁄ genoa ⁄ ⁄ and a ⁄ genoa ⁄ ⁄ presents n d amino acid mutation detected in clade a ⁄ wyoming ⁄ ⁄ -like viruses. the ha sequences of a ⁄ genoa ⁄ ⁄ , a ⁄ genoa ⁄ ⁄ , genoa ⁄ ⁄ , a ⁄ genoa ⁄ ⁄ , and a ⁄ genoa ⁄ ⁄ fell within the clade represented by the ha of a ⁄ califor-nia ⁄ ⁄ ; among these isolates, a ⁄ genoa ⁄ ⁄ and a ⁄ genoa ⁄ ⁄ showed antigenic site sequences very close to that of the ⁄ vaccine strain, whereas ha sequences of a ⁄ genoa ⁄ ⁄ , a ⁄ genoa ⁄ ⁄ ⁄ and a ⁄ genoa ⁄ ⁄ posses amino changes onto antigenic site a(r k), c(g e) and d(r k), respectively. the ha sequences of more recent isolates fell within the clade represented by the ha of a ⁄ brisbane ⁄ ⁄ and characterized by the amino acid changes, relative to the ha of a a ⁄ california ⁄ ⁄ , g e and k i, with the exception of a ⁄ genoa ⁄ ⁄ , showing r g and l s amino acid changes present in viruses belonging to a ⁄ nepal ⁄ ⁄ clade. measure of genetic distance between vaccine and circulating strains was calculated as previously described by gupta. two blood samples were collected from each subject, just before and ± day post-vaccination. all sera were stored at ) °c. all samples were tested at the laboratory of health sciences department, university of genoa, by haemagglutination-inhibition (hi) and neutralization (nt) assays, performed following the who criteria and standardised method in our laboratory, respectively. [ ] [ ] [ ] guinea pig red blood cells were used for hi assay. all samples were assayed twice for hi and for nt. the obtained antibody titre was expressed as the reciprocal of the last sera haemagglutinating or inhibiting virus dilution. immunogenicity was determined by: geometric mean titre (gmt); mean-fold increase (mfi; ratio of post-to pre-vaccination titre); seroprotection rate (the percentage of subjects achieving an hi and nt titre ‡ iu); and seroconversion rate (percentage of subjects with a fourfold increase in hi or nt antibody titers, providing a minimal post vaccination titer of : ). post-vaccination gmt was reported as ratio, with the corresponding % confidence interval, of gmts after vaccination with mf -adjuvanted vaccine and with non-adjuvanted subunit vaccine. seroprotection and seroconversion rate % confidence interval was calculated using modified wald method. comparisons of seroconversion and seroprotection rates between subunit and mf -adjuvanted vaccine groups have been analyzed by fischer's exact test. the results were evaluated against the committee for medicinal products for human use (chmp) criteria for approval of influenza vaccines in the elderly, which require that at least one of the following criteria be met: mfi > ; seroprotection rate > %, or seroconversion rate > %. furthermore, hi titres were also transformed into binary logarithms, corrected for pre-vaccination status, as described by beyer et al. and were expressed as median titres, with the corresponding °- °i nter-quantile range. comparisons of corrected post-vaccination titers between subunit and mf -adjuvanted vaccine groups were analyzed by wilcoxon test. difference in immunogenicity profile between vaccine groups, expressed by ratio of different parameters, was correlated with genetic and antigenic distance between vaccine and viruses used in the study using spearman test. pre-vaccination titres were not significantly different between vaccine groups, for all strains (data not shown). post-vaccination gmt ratios between mf -adjuvanted and non-adjuvanted vaccine groups determined using hi and nt assays, with the corresponding % confidence interval, according to viral strain are shown in figure . both vaccines met chmp requirements for mfi (> ), seroconversion (> %), and seroprotection rate (> %) against a ⁄ wyoming ⁄ ⁄ -like, with the exception of a ⁄ genoa ⁄ ⁄ and a ⁄ california ⁄ ⁄ -like circulating viruses and against egg-grown a ⁄ wyoming ⁄ ⁄ , a ⁄ california ⁄ ⁄ , and a ⁄ wisconsin ⁄ ⁄ strains; the immune response against a ⁄ genoa ⁄ ⁄ met the requirements for mfi and seroprotection rate only in mf -adjuvanted vaccine group. requirements for mfi, seroconversion, and seroprotection rate against the a ⁄ brisbane ⁄ ⁄ -like virus a ⁄ genoa ⁄ ⁄ and the a ⁄ nepal ⁄ ⁄ -like genoa ⁄ ⁄ viruses and against egg-grown a ⁄ brisbane ⁄ ⁄ strain were reached only in subjects vaccinated with the mf adjuvanted vaccine. a similar pattern emerged from the analysis of mfi, seroconversion and seroprotection rates using nt assays. subjects vaccinated with the mf -adjuvanted vaccine showed significantly higher post-vaccination hi gmts against a ⁄ wyoming ⁄ ⁄ -like, a ⁄ california ⁄ ⁄ -like, a ⁄ nepal ⁄ ⁄ -like and a ⁄ brisbane ⁄ ⁄ like viruses, with the exception of a ⁄ genoa ⁄ ⁄ , and against egg-grown a ⁄ california ⁄ ⁄ , a ⁄ wisconsin ⁄ ⁄ , and a ⁄ brisbane ⁄ ⁄ strains, compared with individuals immunized with the non-adjuvanted vaccine ( figure ). the mf -adjuvanted vaccine also induced significantly higher seroconversion and seroprotection rates against following correction for pre-vaccination status, hi titres were significantly higher for the mf -adjuvanted vaccine group when evaluated against a ⁄ wyoming ⁄ ⁄ -like viruses, a ⁄ brisbane ⁄ ⁄ -like a ⁄ genoa ⁄ ⁄ , and a ⁄ nepal ⁄ ⁄ -like a ⁄ genoa ⁄ ⁄ strain ( figure ). pre-vaccination titre corrected response was higher in subjects vaccinated with mf adjuvanted vaccine also against egg-grown a ⁄ wyoming ⁄ ⁄ , a ⁄ california ⁄ ⁄ ⁄ , a ⁄ wisconsin ⁄ ⁄ , and a ⁄ brisbane ⁄ ⁄ . among viruses more closely related to a ⁄ california ⁄ ⁄ , subjects immunized with mf -adjuvanted vaccine showed a significantly higher corrected titres against a ⁄ genoa ⁄ ⁄ , a ⁄ genoa ⁄ ⁄ , and a ⁄ genoa ⁄ ⁄ strains compared with the non-adjuvanted vaccine ( figure ) . spearman test showed a clear correlation between the distances and the advantage offered by mf expressed by ratio between mfi, post-vaccination gmts, corrected post-vaccination median, seroconversion, and seroprotection rates calculated using hi test in the two vaccine groups. similarly, ratio between mfi, seroconversion, and seroprotection rates calculated with nt test correlated with the genetic and antigenic distance between vaccine and viruses used for the study. the ability of mf to enhance the immunogenicity and to elicit a broader immune response against drifted strains than non-adjuvanted vaccine is consistent with other findings reported during the last decade. [ ] [ ] [ ] in subjects vaccinated with the mf -adjuvanted vaccine containing a ⁄ california ⁄ ⁄ , the immune response, expressed by a number of parameters, such as crude and corrected postvaccination titers, seroconversion, and seroprotection rates calculated using hi and nt assays, is higher than that observed in individuals immunized with subunit vaccine when it is evaluated against a drifted strains, such as a ⁄ brisbane ⁄ ⁄ -like and a ⁄ nepal ⁄ ⁄ -like strains, and against egg-grown a ⁄ brisbane ⁄ ⁄ virus. for the first time in this study, the impact of heterogeneity of circulating strains antigenically close to the vaccine on the antibody response elicited by mf -and non-adiuvanted vaccines is evaluated. immune response against viruses isolated during the ⁄ season, that appear more phylogenetically close to ⁄ vaccine strain a ⁄ wyoming ⁄ ⁄ , was higher in subjects vaccinated with mf -adiuvanted vaccine as demonstrated by higher crude and corrected post-vaccination hi titres and higher postvaccination nt titres, with the exception of a ⁄ genoa ⁄ ⁄ , against whom the nt post-vaccination gmt is identical in mf and subunit vaccine groups. furthermore, hi seroconversion and seroprotection rates were higher in mf vaccine group when evaluated against a ⁄ genoa ⁄ ⁄ and a ⁄ genoa ⁄ ⁄ . as far as the immune response against a ⁄ california ⁄ ⁄ -like viruses, the small number of enrolled subjects did not allow appreciating differences using qualitative response indicators, but crude post-vaccination hi titres were higher in mf vaccine group for all the strains. interestingly, a ⁄ california ⁄ ⁄ -like viruses with at least one amino acid change onto antigenic sites, i.e. a ⁄ genoa ⁄ ⁄ , a ⁄ genoa ⁄ ⁄ , and a ⁄ genoa ⁄ ⁄ , showed a more marked difference in terms of response between the two vaccine groups. individuals immunized with mf -adiuvanted vaccine showed higher corrected post-vaccination hi titres and post-vaccination nt titres in comparison with subjects vaccinated with plain vaccine. these response indicators were similar in the two vaccine groups when the response was evaluated against a ⁄ genoa ⁄ ⁄ and a ⁄ genoa ⁄ ⁄ , which present no amino acid changes onto antigenic sites and identical hi titers respect with a ⁄ california ⁄ ⁄ at molecular and antigenic characterization, respectively. thus, the advantage offered by mf in terms of higher immunogenicity expressed by higher post-vaccination hi titres is observable also against viruses showing antigenic and molecular pattern undistinguishable from vaccine strain, but it became even more evident as the antigenic and molecular distance between vaccine and circulating strains grew. as emerged for a ⁄ genoa ⁄ ⁄ , a ⁄ genoa ⁄ ⁄ , and a ⁄ genoa ⁄ ⁄ , one amino acid was a sufficient change in antigenic sites for -fold decrease of hi titre against homologous vaccine strain to observe -fold higher post-vaccination nt titers (mf ⁄ subunit postvaccination gmt ratio range between ae and ae , figure ) and one-dilution higher corrected post-vaccination hi titers in mf vaccine group ( figure ) . finally, the correlation between the distance and the improvement offered by mf in terms of higher immunogenicity clearly emerged by spearman correlation analysis: it remains wellfounded both using a number of different response parameters obtained from hi and nt assays and calculating the distance by serological and genetic methods. outbreaks of h n pdm in pigs in commercial swine operations have been reported in several countries. in all incidents, epidemiological investigations have linked humans as the possible source of the infection to pigs. experimentally, it was established that the virus is pathogenic and transmits readily in pigs. the natural outbreaks of h n pdm and laboratory studies underscore the threat that the virus poses to the swine industry and highlight the need for developing effective control strategies. in the united states, a trivalent live attenuated influenza vaccine (flumistÒ) has been licensed for use in humans since . in swine medicine, however, temperature-sensitive laivs are not available. currently, only inactivated vaccines are available for pigs, but they provide limited protection against antigenically diverse influenza viruses. additionally, the use of inactivated vaccines has been associated with enhanced pneumonia when immunized pigs were challenged with divergent viruses. thus, the development of laivs has the potential to circumvent the drawbacks associated with commercial vaccines. with the aim of developing laiv temperature-sensitive influenza vaccines against the h n pdm virus, we have used reverse genetics to introduce attenuation markers in the polymerase genes of a swine-like tr h n influenza virus, a ⁄ turkey ⁄ ohio ⁄ ⁄ (h n ) (ty ⁄ ). we chose this isolate because it grows well in both eggs and cell culturebased substrates, displays a broad host range, and has internal genes similar to the h n pdm virus. safety and efficacy studies of the ty ⁄ att vaccine candidates in pigs demonstrated that this vaccine backbone is attenuated in swine and conferred sterilizing immunity upon an aggressive intratracheal challenge of pigs with the h n pandemic virus. thus, introduction of genetic signatures for att in the backbone of a swine-like tr influenza virus resulted in highly attenuated and efficacious live influenza vaccines with promising applications veterinary medicine. -t cells and mdck cells were maintained as previously described. a ⁄ turkey ⁄ ohio ⁄ ⁄ (h n ) (ty ⁄ ) has options for the control of influenza vii ª blackwell publishing ltd, influenza and other respiratory viruses, (suppl. ), - been previously described and it was kindly provided by yehia saif, ohio state university. a ⁄ california ⁄ ⁄ (h n ) (ca ⁄ ) was kindly provided by the centers for disease control and prevention (cdc). generation of recombinant viruses by reverse genetics (rg) was done using a previously described method. the genetic signatures for attenuation were introduced into the pb and pb genes of ty ⁄ . ny : ty ⁄ att is a : reassortant with the surface genes from the a ⁄ new york ⁄ ⁄ (h n ) virus and the ty ⁄ att internal genes. all viruses were amplified in mdck cells to produce viral stocks. twenty-five pigs were divided into five groups (n = ) and intranasally inoculated with tcid ⁄ animal of either h n : ty ⁄ att or with ny(h n ) : ty ⁄ att vaccines diluted in ml of mem. two other groups were similarly inoculated with h n : ty ⁄ wt and h n : ty ⁄ rg and served as controls, whereas a fifth group was mockvaccinated with pbs alone. clinical observations were performed as previously described. , efficacy of h n ty ⁄ att vaccine in pigs fourty pigs were divided in four groups (n = )( table ) . group was vaccinated with tcid ⁄ animal of ny(h n ) : ty ⁄ att through intranasal route, whereas group was vaccinated intramuscularly with ml of an adjuvanted uv-inactivated ca ⁄ vaccine (uvadj-ca ⁄ ). group , non-vaccinated and challenged (nv+ca ⁄ ), and group , non-vaccinated, mock-challenged (nv+mock), were also included. pigs were boosted two weeks later. fourteen days post boost (dpb), pigs from groups - were challenged intratracheally with ml of · tcid of ca ⁄ . following challenge, pigs were monitored using methods as previously described. all statistical analyses were performed using graphpad prism software version ae (graphpad software inc., san diego, ca). the differences were considered statistically significant at p < ae . the ty ⁄ att-based vaccines are attenuated in swine pigs inoculated with wt ty ⁄ viruses developed fever (> °c) that peaked hpi ( figure a) and shed large amounts of in nasal secretions ( figure b) . similarly, viral titers in bronchoalveolar lavage fluid (balf) collected at dpi ranged from to tcid ⁄ ml ( figure c ). at necropsy, the lungs from animals inoculated with these viruses had severe pneumonia ( figure d ). in contrast, none of the animals inoculated with h n or h n ty ⁄ att viruses developed clinical signs following vaccination, indicating that the ty ⁄ att viruses were safe for administration to pigs ( figure a) . correspondingly, there was - fold less virus shedding from the nose of pigs vaccinated with ty ⁄ att viruses as compared to unmodified ty ⁄ viruses. in general, ny(h n ) : ty ⁄ att -vaccinated pigs shed less virus than h n : ty ⁄ att inoculated pigs ( figure b ). in addition, viral titers in balf were significantly reduced (p < ae ) in ty ⁄ attvaccinated pigs as compared to ty ⁄ wt-infected pigs ( figure c ). although both vaccines caused mild gross and microscopic lesions in the lungs, the percentage of lung ae ± ae * ± * ± * ± * balf, bronchoalveolar lavage fluid, uvadj-ca ⁄ , uv-inactivated ca ⁄ vaccine; nv+ca ⁄ , non-vaccinated, challenged positive control group; nv+mock, non-vaccinated, non-challenged negative control group. *significantly different from nv+ca ⁄ control group at p < ae . geometric mean hi titer against ca ⁄ at the day of challenge. à percentage of macroscopic lung lesions given as mean score ± sem. § average viral titer (log ) measure as tcid per ml. -average viral titer (log ) in balf at dpc. involvement was not significantly different from mock-vaccinated pigs, corroborating the clinical findings that these vaccines are sufficiently attenuated in pigs ( figure d, e) . histopathologically, nasal turbinates and trachea obtained from pigs immunized with either vaccine were similar to control animals, as opposed to the wt-inoculated pigs ( figure e ). vaccination with h n ty ⁄ att-based vaccines provides sterilizing immunity against h n pdm in pigs the clinical performance in pigs of the h n vaccines is summarized in table . nv+ca ⁄ animals had macroscopic pneumonia, viral replication in balf and shedding in the nose. uvadj-ca ⁄ vaccine provided satisfactory protection, but this protection was not sterilizing. remarkably, animals vaccinated with ny(h n ) : ty ⁄ att had sterilizing immunity. in both vaccine groups there was a significant reduction (p < ae ) in the percentage of macroscopic lung pathology compared to the nv+ca ⁄ group. control pigs had neither significant macroscopic nor microscopic lesions in the lungs. hi antibody titers measured at the day of challenge in both vaccine groups were approximately the same (table ). in the present study, we developed for the first time, temperature-sensitive laiv for use in pigs. data from our safety studies showed that both the h n and h n ty ⁄ att vaccines were attenuated in pigs. although the ty ⁄ att vaccines were detected in balf samples, the level of viral replication was significantly reduced in comparison to unmodified virus and, more importantly, caused no overt clinical signs. a minimal amount of replication is likely beneficial for eliciting t-cell responses to internal genes that may provide heterologous cross-protection. one of the most challenging tasks in producing effective live attenuated vaccines is to achieve an adequate balance between safety and efficacy. by introducing the att modifications into the polymerase genes of a swine-like tr strain, this desirable balance was achieved. the vaccines were histopathologic scores of nasal turbinates, trachea and lungs at dpi. ny(h n ) : ty ⁄ att (a virus that carries the surface genes of a ⁄ new york ⁄ ⁄ (h n ) and ty ⁄ att internal genes). all h n viruses have their surface genes derived from ty ⁄ . values are shown as the mean ± sem. * p < ae ; **p < ae ; *** p < ae . options for the control of influenza vii ª blackwell publishing ltd, influenza and other respiratory viruses, (suppl. ), - attenuated in pigs and, more importantly, provided sterilizing immunity upon an aggressive challenge with pandemic h n as opposed to an experimental ca ⁄ inactivated vaccine, which elicited protective but not sterilizing immunity in all animals. in the face of influenza pandemics that have the ability to overcome the species barriers such as the h n , the supply of vaccines for use in agriculture could be jeopardized. our cell culture-based live att h n vaccines could be an attractive alternative for this possible pandemic vaccine shortage. because the ty ⁄ att live vaccines developed here are efficacious in swine, are easier to manufacture than inactivated vaccines, and do not require adjuvants, our study represents a major advance in vaccine development for the h n pandemic. in conclusion, our second generation of live att influenza vaccines based on modifications of the pb and pb genes of ty ⁄ retains its safety properties in vivo and can induce excellent protection against aggressive h n challenges in the swine host. influenza virus is one of the most important respiratory pathogens worldwide. , type a influenza causes an acute disease of the upper airways, and affects - million persons yearly. moreover, the threat of human influenza epidemic and pandemic has dramatically increased in recent years. vaccination is one of the crucial interventions for reducing the spread and impact of influenza. the generally used parenteral inactivated influenza vaccines induce mainly systemic antibody responses and only weak cell-mediated immunity and low levels if any mucosal immunity. on the other hand, intranasal immunization with live virus can induces a broad spectrum of both systemic and mucosal antibodies, and the immune response localized in the mucosa blocks the virus even during the first phase of infection. unfortunately, the use of live vaccines is always associated with a certain risk. the development of a crossprotective vaccine against potentially pandemic strains is an essential part of the strategy to control and prevent a pandemic outbreak. we induced intrasubtypic and intersubtypic cross-protection in balb ⁄ c mice by intratracheal (it) immunization with inactivated influenza viruses together with dead delipidated bacillus firmus (dbf) as an adjuvant. ten days after the nd immunization dose, the mice were infected with live influenza virus b ⁄ lee ⁄ lethal for mice (total infection dose corresponded to · ld ) or a⁄ pr ⁄ (total infection dose corresponded to ae - ld ). dbf adjuvant markedly increased both systemic and mucosal anti-viral antibody formation when applied together with inactivated influenza a or b viruses. protective significance was tested in vivo. mice were preimmunized with ) pbs (controls), ) dbf alone, ) virus alone, and ) vir-us+dbf. influenza b virus strains b ⁄ lee and b ⁄ yamanashi ⁄ ( years phylogenetically distant and antigenically substantially different, especially in terms of the main protective antigen -surface haemagglutinin) or two different influenza a subtypes -a ⁄ pr ⁄ (h n ) and a ⁄ california ⁄ (h n ) -were used (figures and ) . the mice were challenged with · ld of either b ⁄ lee ⁄ or a ⁄ pr ⁄ as appropriate. all controls died. the mice treated with dbf alone died with a delay or survived, which could be explained by stimulation of innate immunity. the animals immunized with virus alone were protected against homologous strains. adjuvant immunization was cross-protective: the mice immunized with a heterologous b strain (figure ) fell ill (pronounced body mass loss), but almost all survived and recovered. the mice immunized with a heterologous a subtype were excellently protected (negligible weight loss and zero mortality). intratracheal dbf ( lg per mouse) given to non-immunized mice hour before influenza infection eliminated the lethal effect in - % of infected animals depending on infection dose ( ae - ld ); in mice infected with lower than lethal doses ( ae ld ), weight loss was minimized or did not occur. the current mode of vaccination-induced immunity is mostly effective against a homologous strain of the virus used for vaccination. the attention is therefore focused on vaccines that are able to induce cross-protection and could be effective also in case of sudden appearance of a new virus variant. inactivated influenza viruses are known to be often insufficiently effective when used for mucosal immunization and for induction of cross-protection against drifted influenza viruses or novel subtypes. the drawback of vaccination with dead virus can be overcome by using a suitable adjuvant. mouse models were successfully immunized with vaccine containing inactivated virus in combination with cholera toxin or the escheria coli heat-labile toxin (lt). [ ] [ ] [ ] the use of cholera toxin in humans is precluded because of its high toxicity; a number of lt mutants that retain their adjuvant activity have been prepared; these mutants were likewise tested on the mouse model and should not cause any serious side effect in humans. for this reason, current studies aim at finding a suitable and safe mucosal and systemic immune response. dbf has been shown to be a very efficient adjuvant for mucosal immunization stimulating both innate and adaptive immunity. intratracheal immunization with inactivated influenza viruses and dbf as adjuvant induced efficient and even heterosubtypic cross-protection. dbf given hour before infection provided partial protection probably because of its strong stimulatory effect on the innate immunity. temperature-sensitive and cold-adapted candidates for live attenuated influenza vaccine with genomic composition of : based on highly pathogenic influenza a ⁄ h n viruses with pandemic potential were generated by the replacement of six internal genes from the influenza a ⁄ puerto rico ⁄ ⁄ (pr ) virus from pr -based rg-candidates for inactivated vaccine with appropriate internal genes of influenza a ⁄ leningrad ⁄ ⁄ ⁄ (h n ) master donor virus (mdv) for russian laiv by methods of classical reassortment. all attempts to capture avian n neuraminidase into the genome of the mdv laiv production were ineffective. : reassortants were not generated. step by step co-infection of triple reassortants (h n -h n -h n ) with h n mdv in some cases was the only possibility to generate influenza a ⁄ h n cold-adapted vaccine reassortants. difficulties in generating : reassortants could be explained by a substantial gene constellation in the genome of pr based h n reassortant viruses. strong coupling of pb ⁄ pr and avian n genes in a ⁄ h n -pr -rg reassortants was revealed. annually updated laiv strains are generated by classical reassortment of circulating influenza viruses with well characterized, attenuated, ts ⁄ ca mdvs. resulting attenuated reassortants inherit the relevant ha and na of wild type parental virus and six internal genes of the mdv. candidates for inactivated influenza vaccines based upon avian influenza viruses with pandemic potential are generally generated by reverse genetics methods. in these cases, like with laiv, vaccine strains are : reassortants which possess the modified ha and na from potentially pandemic virus and six internal genes from the pr virus. the pr virus is considered to be of low virulence, i.e. attenuated, for humans, yet offers properties of high seed virus growth for influenza vaccine production. the ha of avian h influenza viruses with pandemic potential is engineered to remove four basic amino acid codons from the cleavage site of ha, resulting in a virus that is considered attenuated for natural hosts and safe for people. the objective of this study was to safely generate vaccine candidates for a laiv using highly pathogenic avian influenza viruses by the replacement of six internal pr genes in the genome of candidates for inactivated vaccine subtype h n (a ⁄ h n -pr -rg) with internal genes of the laiv mdv by methods of classical reassortment. len -mdv and a ⁄ h n -pr -rg virus were co-infected in embryonated chicken eggs. five rounds of selective propagation were performed, three of which were at low temperature ( °c). the production and selection of reassortants were carried out in the presence of rabbit antiserum to len -mdv. cloning by endpoint dilution was performed in each of the last three passages. a virus sample in an open petri dish was rocked gently for sec while being irradiated with a ge watt germicidal lamp at a distance of cm from the dish. the residual infection titer was measured by titration in embryonated chicken eggs. genome composition of reassortant viruses was monitored by rflp analysis. in addition, capacity of reassortant viruses to grow at optimum, low, and elevated temperatures (ca ⁄ ts phenotype) for influenza viruses was determined by virus titration in chicken eggs. reassortment of the mdv with the vn-pr or indo-pr viruses either resulted in reassortants that contained six internal genes from len -mdv. however, all generated clones contained the na from the mdv. of ten such : reassortants based on vn-pr three reassortants had the pa gene from pr and one had ns gene from pr . : reassortants from the targeted h n composition were not generated. after repeated attempts, : temperature sensitive and cold adapted reassortants based on vn-pr and indo-pr viruses were obtained, but again, none had inherited the avian n neuraminidase (table ) . in contrast, nibrg- didn't reassort with the mdv at all. twelve unsucsessful attempts to develop : or : reassortants of nibrg- with mdv showed that the classical reassortment procedure (cloning by limited dilutions in the presence of anti-mdv serum, followed by co-infection of equal doses of two parental viruses in eggs and two selective passages at °c) did not work for this virus pair. to disharmonize the incredibly strong gene constellation of nibrg- , various modifications of the co-infection step were studied, such as: altering the nibrg- to mdv ratio (from : to : tions of anti-mdv serum alone or together with anti-pr serum. it was noted that even if the h n to mdv ratio was : , the clones obtained were presumably parental h n viruses without the transfer of any mdv-genes into genome of nibrg- . in all, clones were isolated, and of them were identical to nibrg- parental virus. in nine clones, only the pa gene from mdv was included, whereas in three clones only the 'cold' ns gene was included (data not shown). using uv inactivation of nibrg- prior co-infection was more encouraging. after the first round of co-infection of partially uv-inactivated nibrg- with mdv (at ratio : ), reassortants that inherited several internal genes of mdv were obtained in the context of the nibrg- background (b , c , c , d ) ( table ). some of them (c , c , d ) were chosen for the next round of co-infection. after the second round of co-infection, c , c , and d 'intermediate' reassortants with mdv (at ratio : or : ) : vaccine reassortants finally were obtained. live attenuated influenza vaccine is considered as one of the most promising pandemic vaccines. according to the who there is evidence that laiv might be more effective than inactivated vaccines. this study attempted the safe development of laiv for potential pandemic highly pathogenic avian a ⁄ h n viruses on the base of rg-reassortants for inactivated vaccine with modified h hemagglutinin and mdv for laiv. replacement of pr based internal genes into genome of vn-pr and indo-pr reassortants with appropriate genes of mdv was realized by the classical reassortment procedure. difficulties were encountered in obtaining : reassortants that contained both the ha and na from the wild type avian h n parental virus. in attempts to reassort the nibrg- with mdv, the classical reassortment procedure was unsuccessful. the challenge faced was to break an incredibly strong gene constellation of the nibrg- virus. partial uv-inactivation of nibrg- was encouraged in replacement of some pr internal genes with mdv genes in some cases avian-human reassortant viruses with gull h n and human influenza h n genes were difficult to generate, and reassortants with the desired genotype of six gull virus genes with human influenza a h and n genes were not isolated despite repeated attempts. the gull pb , np, and ns genes were not present in any of the gull-human h n reassortants generated. it is difficult to fully understand potential reasons for observed difficulties to reassort some avian viruses with human strains. unsuccessful attempts to develop : vaccine reassortants may be caused by an observed strong connection of pb and na genes in the genome of a ⁄ h n -pr -rg viruses. in our attempts, each reassortant that possessed avian n neuraminidase inheritied pb gene of pr as well. and vice versa, the 'cold' pb gene always appeared to be coupled with the n neuraminidase of the mdv. in some cases, step by step co-infection of triple reassortants (h n -h n -h n ) with h n mdv may be the only possibility to generate a cold-adapted vaccine reassortant. our studies demonstrate unique and significant challenges that are faced in the development of influenza vaccines for avian influenza viruses with pandemic potential. such challenges must be further studied to identify methodologies to allow for rapid development and response to emerging viruses in a crisis. it is imperative that these studies be continued and expanded to identify either mechanisms of such tight gene constellations in influenza viruses produced by rg-derived vaccine strains or inability some genes of human h n and avian h n viruses to cross. in addition, further studies to improve the efficiency of classical reassortment processes will be conducted. during the period from to , avian influenza outbreaks among humans have been registered in countries of asia, europe, and africa. morbidity and mortality of humans followed the global spread of avian influenza h n among wild and domestic birds, which caused great economic loss to the poultry industry in many regions including some highly developed countries. the global threat from avian influenza forced scientists to develop technologies for the production of a ⁄ h n human vaccine. the development of ai a ⁄ h n vaccines using strains isolated in kazakhstan and the organization of local production and creation of strategic stockpiles of effective vaccines is the an important issue for public health protection in the republic of kazakhstan. to address this, a scientific program 'influenza a ⁄ h n vaccine development for public health protection in kazakhstan' was approved and financed from to . in this article we give basic results of the development of a recombinant ai a ⁄ h n inactivated whole virion vaccine with aluminium hydroxide as adjuvant for public health protection in kazakhstan. [ ] [ ] [ ] the development of vaccine technology was conducted with the use of a ⁄ astanarg ⁄ : ⁄ (a ⁄ h n ) recombinant strain made of a ⁄ chicken ⁄ astana ⁄ ⁄ (h n ) and a ⁄ pr ⁄ ⁄ (h n ) strains by the reverse genetics. inactivation of virus containing allantoic fluid was carried out with the use of formalin in different concentrations. complete-ness of the virus inactivation was tested by -fold virus passaging in embryos. , purification and concentration of the inactivated viruscontaining allantoic fluid was conducted with the use of ultra filtration in tangential flow, which was followed by gel filtration. then we evaluated the content of total protein, hemagglutinin, and ovalbumin in purified and concentrated material. vaccine was composed of clarified and inactivated virus concentrate with the known ha dose containment, and ae % aluminum hydroxide was added in : proportions. composition components and quality control of finished vaccine was determined in the stages of semi-finished product and finished biopreparation. determination of quantitative ovalbumin content was conducted by elisa applying a strip test-system chicken egg ovalbumin elisa kit cat. n (alpha diagnostic international, usa). vaccine immunogenicity was evaluated by hai micro test in u-bottom -well plates produced by 'costar' (usa). vaccine apyrogenicity was evaluated after intravenous injection of the studied preparation to rabbits. , for confirmation of the results vaccine series were tested for bacterial endotoxins with the use of limulus amebocyte lysate produced by charles river laboratories, inc. usa. the vaccine toxicity was evaluated in white mice with body weight - gm and in rats with body weight - g both males and females according to glp principles. allergenic characteristics of the inactivated vaccine was determined in white outbred mice and guinea-pigs both males and females according to 'methodic guideline for evaluation of allergenic characteristics of pharmacological substances'. in the first series of experiments, we conducted work for obtaining influenza a(h n ) recombinant strain. bidirectional expression plasmid phw_b with full-length sequences of ha and na gene segments of the strain a ⁄ chicken ⁄ astana ⁄ ⁄ (h n ) isolated in kazakhstan were synthesized in geneart ag, (regensburg, germany). ha gene was modified by deleting the region encoding multiple basic amino acid rrrk motif in ha cleavage site. moreover, to prevent recovery of repeating basic amino acids motif due to polymerase slide, we inserted replacements g fi t and k fi t. thus the ha cleavage site consists of the following sequence ntpqgerrrkkrglfgai ntpqtetrglfgai. the basic amino acid motif of highly pathogenic strain a ⁄ chicken ⁄ astana ⁄ ⁄ (h n ) was replaced by the sequence tetr ⁄ glf, which is characteristic of low pathogenic strains of influenza h n . sequence of gene coding na in the strain a ⁄ chicken ⁄ astana ⁄ ⁄ (h n ) was cloned without modifications. the other segments pb , pb , pa, np, m and ns were obtained from influenza virus ivr- and synthesized and cloned in two-forked expression plasmid phw_b in geneart ag company, germany. the origin of genetic segments of vaccine strain a ⁄ astanarg ⁄ : ⁄ (h n ) is presented in table . vero cell culture ( passage) (who) was received from european cell culture collection (salisbury, wiltshire sp jg, great britain). the cell culture was grown in dmem ⁄ f medium with the addition of % of fetal bovine serum and mm l-glutamine. to obtain reassortant virus a ⁄ astana ⁄ ⁄ r- : , vero cells were infected with correlative plasmids by way of electroporation using nucleofector ii (amaxa) equipment. infected cells were placed in -well plates. after hour, dmem ⁄ f medium was changed into ml of opti-pro sfm (gibco) medium adding mm l-glutamine and lg ⁄ ml trypsin. two days after cytopathic effect appearance supernatant was collected and used for infection of spf-eggs. the virus a ⁄ astanarg ⁄ ⁄ - : was grown in chicken embryos, and then virus titer was determined in chicken embryos and madine-darby canine kidney (mdck) cell culture. the titer of two final a ⁄ astanarg ⁄ - : virus stocks was ae log eid ⁄ ml (chicken embryos); ae log tcid ⁄ ml (mdck cells); ha titer : . a ⁄ chicken ⁄ astana ⁄ ⁄ (h n ) virus contains motif of repeating basic amino acids in ha cleavage site. it is known that this sequence is the main determinant of ai virus pathogenicity. that is why this site was deleted in vaccine candidate strain. sequence results confirmed that influenza virus a ⁄ astanarg ⁄ ⁄ r- : strain ha gene sequence contains modified ha cleavage site and keeps mutations inserted for prevention of return to virus wild type. to confirm stability of modified ha gene sequence, five additional passages of recombinant strain a ⁄ astana rg ⁄ ⁄ - : were conducted in chicken embryos. sequencing and following phylogenetic analysis of the recombinant strain a ⁄ astana rg ⁄ ⁄ - : ha gene sequence proved the presence of modification in ha cleavage site. deletion of pathogenicity site of the obtained virus was confirmed by lethality test for chicken embryos, intravenous pathogenicity test in chicken, and in plaque-forming test with trypsin. pathogenicity test in chicken embryos showed that recombinant strain a ⁄ astanarg ⁄ - : is capable of growing up to high titers without causing embryos' death. a ⁄ astanarg ⁄ - : strain pathogenicity evaluation was conducted in - week-age white leghorns chicken, and this study proved that the strain a ⁄ astanarg ⁄ - : (h n ) is not virus pathogenicity inductor in chickens, which got intravenous injections of this virus (pathogenicity index is equal to ). h n strain ha cleavage site modification provides its cleavage capability only with tripsin-like proteases, which shows low level of pathogenicity. aiming at confirmation of ha cleavage site modification, we experimentally studied virus replication ability both with trypsin and without this enzyme. and we got the following results. in the plaque-forming test, a ⁄ astanarg ⁄ - : strain produced plaques in mdck cells only with trypsin, proving the trypsin-dependent phenotype characteristic of low pathogenic avian influenza viruses. to prove the ha subtype antigenic analyses of a ⁄ astana ⁄ ⁄ r- : strain was conducted by means of serological methods in hemagglutinin inghibition test with the use of postinfection antisera of rabbits and rats (influenza research institute swd rams), standard serum received from cdc, atlanta, usa. hai test proved that a ⁄ astana ⁄ ⁄ r- : strain belongs to h subtype. furthermore, toxicity of vaccine candidate strain was evaluated by way of subcutaneous injection of viral material to balb mice. the strain appeared to be non-toxic for white mice getting subcutaneous injection of ae ml of the preparation. the conducted research showed that according to all tested characteristics, a ⁄ astana ⁄ ⁄ r- : strain can be used for influenza a ⁄ h n inactivated vaccine production. according to its genetic characteristics, this strain belongs to the group of vaccine strains recommended by who for the development of influenza pre-pandemic inactivated vaccines. we determined basic cultivation parameters of the recombinant strain a ⁄ astanarg ⁄ - : in - day chicken embryos. the determined parameters are the following: infection dose, - eid ; cultivation period, hour; incubation temperature, °c. these cultivation parameters allow obtaining virus containing material with biological eid and hemagglutinating activity of ae - ae log eid ⁄ cm and : ha titre and even higher. in the next series of experiments, we conducted research on the determination of optimal sequence of technological stages of virus clarification, concentration, and inactivation in the order of vaccine production. samples of viral material were subjected to inactivation before and after clarification and concentration. the regimen of virus inactivation by formaldehyde with final concentration of ae %, period of inactivation of days, temperature of inactivation medium of - °c, ph of inactivation medium of - ae . on the basis of the conducted experiments we determined that the selected regimen of inactivation provides complete and irreversible inactivation of viral suspensions of the hpai strain irrespective of the kind of inactivated material. we did not observe reduction of ha activity in non-clarified viral suspensions. however, when we inactivated clarified and concentrated material, ha activity reduced by an order of magnitude. comparison of forms and sizes of virion structural elements in native (non-clarified) and formalin inactivated preparations did not reveal any significant differences. concentration of virus particles in the studied preparations was similar. the selected inactivation regimen provides obtaining completely avirulent viral suspension of the strain a ⁄ astanarg ⁄ - : , and it does not influence the structure of the virus. on the basis of the experiments results, we selected method of viral allantoic fluid inactivation without preliminary clarification. during further research, we tried to get highly clarified viral concentrate. this study resulted in the combined scheme, which includes clarification of inactivated viral allantoic fluid by low speed centrifugation at circulations per min for minutes, filtration through membrane filters with pore diameter of ae lm, ultrafilatration ⁄ diafiltration, gel filtration in b sepharose, and sterilization of viral suspension through membrane filters with pore diameter of ae lm. the experiments resulted in the development of production technology of embryonic inactivated vaccine based on recombinant strain a ⁄ astanarg ⁄ : ⁄ (h n ) contain-ing aluminium hydroxide as adjuvant. the developed influenza a ⁄ h n human vaccine has the trade name kazfluvacÒ. its composition components are presented in table . preclinical testing of the vaccine kazfluvacÒ was conducted according to the following parameters: general health condition of animals, change of body weight and temperature of immunised animals (for ferrets), presence of post vaccination antibodies response in sera, forming protective immune response against reassortant viruses of h subtype, study of acute and chronic toxicity of three experimental vaccine series in different doses and semi-finished vaccine product applying different ways of injection, study of allergic and immunotoxic characteristics of the vaccine, as well as study of pyrogenic reaction and analysis for bacterial endotoxins presence. [ ] [ ] [ ] [ ] preclinical tests of kazfluvacÒ vaccine safety showed that this vaccine does not have toxic effect on organisms of warm-blooded laboratory animals. double intramuscular injection of kazfluvacÒ vaccine in inoculative dose does not effect appearance, general health condition, behaviour of animals, their muscular strength and physical activity, does not have negative effect on biochemical parameters of blood and basic physical functions of animals organism, and does not cause pathomorphological changes. this shows the safety of the vaccine. local irritation action was not observed. the results of the vaccine allergic action study showed that the vaccine does not have allergic effect at the intravenous injection. the research also showed that the vaccine does not have negative effect on immune system of laboratory animals. research conducted on mice and ferrets showed high immunogenic activity of the vaccine at one-and two-dose regimen of injection. the research showed % of protective effect of kazfluvacÒ vaccine at two-dose injection regimen in ferrets infected by homological strain of influenza virus. the devised inactivated influenza a ⁄ h n vaccine kaz-fluvacÒ is a safe and immunogenic biopreparation that is not worse than the overseas analogues in its immunobiological characteristics. [ ] [ ] [ ] [ ] to date the whole-virion inactivated influenza a ⁄ h n vaccines of the producers such as omnivest (hungary), biken, denka seiken, kitasato institute, kaketsuken (japan), gsk biologicals (belgium), sinovac biotech (china) are registered. all of them are produced on the basis of chicken embryos and aluminum is used as an adjuvant. kazfluvacÒ differs from its analogues in the flowchart of the virus purification and concentration that makes possible to produce a safer preparation. , the results of the conducted research and preclinical testing allow starting work towards implementation of phase i preclinical tests on volunteers. it is planned to conduct a randomized blind placebo-controlled phase i study on double application of kazfluvacÒ vaccine in increasing doses. the preparation will be administered to volunteers aged - years for assessment of its safety and immunogenicity in doses of ae and ae lg of ha. when the world health organization (who) announced the sixth phase of a ⁄ h n v influenza pandemic, scientists all over the world started investigation to develop technology for production of prophylactic means against the disease. having taken into consideration the threat of a pandemic for kazakhstan, the ministry of education and science of the republic of kazakhstan launched the program ''monitoring, study, and development of diagnostic, prophylactic, and therapeutic means for influenza a ⁄ h n .'' this paper presents the experimental data obtained at the ribsp in the course of the studies towards the development of technology for production of an inactivated a ⁄ h n influenza vaccine, as well as the results of pre-clinical testing of the developed vaccine. the development of vaccine production technology was conducted with the use of who recommended vaccine strain nibrg- xp constructed by the method of reverse genetics in the national institute for biological standards and control (nibsc, great britain). the virus was inactivated with formalin at different final concentrations, and the extent of inactivation was evaluated via threefold virus passages in developing chicken embryos. the inactivated virus was purified and concentrated by the method of ultrafiltration in tangential flow followed by gel filtration. the purified and concentrated material was evaluated judging on the total protein, hemagglutinin (ha), and ovalbumin. the vaccine was prepared by pooling the purified and concentrated virus material with the certain weight content of ha and the work solution of aluminum hydroxide ( ae %) in the ratio : . the ovalbumin content was quantified in elisa with the use of the strip test system chicken egg ovalbumin elisa kit (cat. no. alpha diagnostic international, san antonio, texas, usa). weight content of the virus ha was determined according to sominina, burtseva. the content of the residual formaldehyde, aluminum (al + ) ions, and thiomersal in the vaccine was measured according to the operating instructions. the vaccine immunogenicity was assessed in the hemagglutination inhibition test, which was carried out as a microassay in -welled u-bottomed plates (''costar'', new york, usa). , apyrogenicity of the vaccine was assessed post intravenous administration of the tested preparation to rabbits. , to confirm the obtained results the vaccine batches were tested for bacterial endotoxins with use of the limulus amebocyte lysate (charles river laboratories, inc., wilmington, ma, usa). the toxicity of the vaccine was assayed in white mice weighing - g and in rats weighing - g (male and female) in compliance with the principles of good laboratory practice. allergenic properties of the inactivated vaccine were determined according to the ''operating instructions on assessment of allergenic properties of pharmaceutical substances'' in white outbred laboratory mice and guinea-pigs of both sexes. the first step in the course of developing technology for vaccine production was to determine the major conditions for influenza virus cultivation: usage of -days embryonated chicken eggs at the infectious dose within - eid , incubation temperature ( ± ae )°c, and duration of the incubation period hours. the established parameters for virus cultivation made it possible to produce virus-containing materials of infectious activity within ae - ae log eid ⁄ cm and hemagglutinating activity : and higher. in the subsequent experiments, an optimal method for virus inactivation was selected. on the basis of the experimental findings, the following conditions for inactivation of the native virus-containing material were elected: formalin of ae % final concentration as an inactivating agent; inactivation period of hours at temperature ( ± )°c. these conditions provide the complete inactivation of the virus (nibrg- xp strain) material, did not impact distinctly the structural organization of the virus, and did not reduce the antigenic activity. as it is well known, virus purification and concentration means very much in the development of technology for production of an inactivated whole-virion influenza vaccine. the investigation into optimization of the technological step of purification and concentration of the recombinant influenza virus nibrg- xp strain resulted in selection of an optimal pattern including such steps as clarification of the virus suspension by filtration through membranes with pore size ae lm, virus concentration by ultrafiltration in a tangential flow, dialysis filtration in a tangential flow, gel filtration on sepharose b, and sterilization of the viral suspension through membrane filters with pore size ae lm. the studies conducted by the ribsp specialists resulted in the development of technology for production of the first domestic whole-virion inactivated a ⁄ h n influenza vaccine with aluminum hydroxide as adjuvant and with the brand name refluvac Ò . the key processing characteristics of the whole-virion inactivated a ⁄ h n influenza vaccine vaccine refluvac Ò are shown in table . simultaneous with the performance of all process operations, the parameters such as sterility, inactivation extent, ph, vaccine specificity, total protein content, weight content of has, aluminum and formalin contents, content of thiomersal, and ovalbumin, pyrogenicity of the vaccine and its immunogenicity for mice, were optimized. the key qualitative characteristics of the designed influenza a ⁄ h n vaccine refluvac Ò are shown in table . before implementation of phase i clinical trials on volunteers, preclinical testing of three experimental batches of refluvac for immunogenic activity and safety was carried out. it was conducted in three laboratory bases of research institutions: the toxicology institute ⁄ federal medicobiological agency, russia (st petersburg), the research institute for biological safety problems (republic of kazakhstan), and the influenza research institute ⁄ north-western branch of the russian academy of medical sciences (st petersburg), with use of different animal models (mice, rats, chinchilla rabbits, guinea-pigs, ferrets). the results of the preclinical testing are as follows: • electron microscopy of the preparation has shown that the viral particles are well dispersed and do not aggregate. the portion of whole (intact) particles is over %, which is evidence of virion integrity; • assessment of polypeptide composition of the vaccine refluvac by electrophoresis in % polyacrylamide gel with sodium dodecyl sulfate has shown the vaccine to contain both surface antigens (ha, na) and highly purified inner virion proteins (np, m ) that are typespecific antigens, so the vaccine is a preparation of full immunological value; • judging on the parameters of acute and chronic toxicity for white mice and rats of both sexes, the vaccine is a non-toxic and safe preparation; • under conditions of a chronic experiment on white mice and rats, it was found that refluvac does not produce changes in behavior, somatic, or vegetative responses; • assay of hematological and biochemical blood characteristics of white mice and rats following vaccine administration did not reveal any significant differences as compared to the animals of the control group; • refluvac does not cause allergenic and immunotoxic impact; • the vaccine refluvac does not cause local irritative effect; • refluvac is apyrogenic for laboratory animals; • the pathomorphological and hystopathological analysis did not reveal any changes due to immunization in animal organs; • testing of immunogenic characteristics of the vaccine on mice and ferrets has shown formation of hemagglutinating antibodies in animals after single administration; • refluvac induces % protection in immunized ferrets at their challenge with the wild-type influenza virus a ⁄ california ⁄ ⁄ (h n v). the results of the performed preclinical testing have allowed concluding that refluvac, an inactivated whole-virion vaccine with aluminum hydroxide as adjuvant, is a safe and highly effective preparation against influenza a ⁄ h n v. the implemented study resulted in development of technology for production of the first domestic inactivated allantoic whole-virion influenza a ⁄ h n vaccine with aluminum hydroxide as an adjuvant under the brand name refluvac Ò based on the recombinant strain nibrg- xp. the devised pandemic vaccine meets who requirements as well as requirements concerning safety and immunogenicity of the national pharmacopeias of the republic of kazakhstan and russian federation. [ ] [ ] [ ] [ ] the devised technology for vaccine production differs from the previous technologies for production of allantoic whole-virion influenza a ⁄ h n vaccines in its processdependent parameters. presence of an adjuvant (aluminum hydroxide) increases significantly the vaccine immunogenicity and allows maximal reduction of the dose of the administered antigen that, in turn, results in diminished reactogenicity of the vaccine. aluminum hydroxide is an adjuvant that is most frequently used in clinical practice. to date the results of the double-centered randomized study of the europe-licensed vaccine fluval p [monovalent inactivated whole-virion influenza vaccine with aluminum phosphate based on strain a ⁄ california ⁄ ⁄ (h n ) nymc x- a (omninvest, pilisborosjeno, hungary)] that is similar to the refluvac preparation are published. the data of this research are an evidence of safety and high immunological effectiveness of the vaccine in dose lg ha at single administration both in adults and elderly persons. the results of the pre-clinical tests allow recommending carrying out phase clinical testing of the refluvac Ò vaccine for safety and immunogenicity. single immunization of volunteers with refluvac Ò in doses ae , ae , and ae lg of ha are planned. mid , respectively. the study results confirm that new h n laiv and h n laiv candidates are safe and immunogenic and confer protection from homologues influenza virus infection in mice. the recent emergence of a new pandemic h n virus and the threat of transmission of avian viruses to humans had stimulated research and development of live attenuated cold-adapted influenza vaccines against newly appeared influenza viruses. formulations of live attenuated influenza a vaccine (laiv) against pandemic influenza strains, including h n , h n , h n , and h n are currently being tested in preclinical and phase i clinical studies. the following paper describes the preclinical study of new h n and h n laiv candidates in mice. the study addressed the following three objectives: (i) to demonstrate that cold-adapted (ca) reassortant influenza a(h n ) and a(h n ) vaccine candidates are indistinguishable from the parental a ⁄ leningrad ⁄ ⁄ ⁄ (h n ) master donor strain (mds) virus with regard to replication efficiency in upper and lower respiratory tract of mice; (ii) to demonstrate the immunogenicity of different doses of cold-adapted (ca) reassortant influenza a(h n ) and a(h n ) vaccine candidates in mice; and (iii) to demonstrate the protective efficacy of cold-adapted (ca) reassortant influenza a(h n ) and a(h n ) vaccine candidates in mice against a homologous wild-type virus challenge. the a ⁄ ⁄ mallard ⁄ netherlands ⁄ ⁄ (h n ) reassortant containing the ha and na genes from a ⁄ mallard ⁄ netherlands ⁄ (h n ) and six other genes from mds, the a ⁄ ⁄ california ⁄ ⁄ (h n ) reassortant containing the ha and na genes from a ⁄ california ⁄ ⁄ (h n ) and six other genes from a ⁄ leningrad ⁄ ⁄ ⁄ (h n ) were generated by classical genetic reassortment in embryonated chicken eggs (ec). viruses were propagated in days old eggs ( °c, hours). fifty percent egg infectious dose (eid ) titers were determined by serial titration of viruses in eggs. titers were calculated by the method of reed and muench. female balb ⁄ c mice, - weeks of age were used in all experiments. mice were lightly anesthetized with ether and then inoculated intranasally (i.n.) with ll of infectious virus diluted in phosphate-buffered saline (pbs). mice were inoculated with mid ( % mouse infectious dose) of a ⁄ ⁄ california ⁄ ⁄ (h n ), a ⁄ ⁄ mallard ⁄ netherlands ⁄ ⁄ (h n ), and a ⁄ leningrad ⁄ ⁄ ⁄ (h n ) mds. viral loads were measured in respiratory and brain tissues collected at and days post-infection (dpi). tissue homogenates prepared using a disruptor and clarified supernatants were titrated on eggs at permissive temperature to determine infectious concentrations. groups of animals were inoculated with mid or mid of either h n laiv or h n laiv intranasally after collecting a pre-immunization blood sample. a second blood sample was collected at dpi. on the same day, the animals received a second intranasal inoculation with the same virus that was used for priming at dpi. to assess protection, all animals were infected dpi with either mid of a ⁄ california ⁄ ⁄ (h n ) or mid a ⁄ mallard ⁄ netherlands ⁄ (h n ) virus by the intranasal route. four animals from each group were euthanized at dpi, and the respiratory and systemic organs were harvested for virus titration. a forth blood sample was collected at dpi from the remaining animals. hi antibody titers were determined for individual serum samples collected on days , , , and . body weights were taken daily following challenge through day postchallenge. sera were tested for hi against homologous h n and h n viruses. the h n laiv, h n laiv and h n mds influenza viruses replicate in mice lungs at level ae - ae lgeid ⁄ ml at dpi (figure ). at dpi, replication of the viruses in the lungs decreased to ae - ae lgeid ⁄ ml (data not shown). in contrast, the wild-type virus a ⁄ mallard ⁄ netherlands ⁄ (h n ) demonstrated high level replication in lungs - ae lgeid ⁄ ml. the levels of replication of studied viruses in nasal turbinates were ae - ae lg eid ⁄ ml at dpi (figure ) , and ae - ae lgeid ⁄ ml at dpi (data not shown). there were no significant differences between the viruses in regard to replication in upper respiratory tract of mice. thus, it was shown that a ⁄ ⁄ mallard ⁄ netherlands ⁄ ⁄ (h n ) and a ⁄ ⁄ california ⁄ ⁄ (h n ) vaccine candidates was indistinguishable from parental a ⁄ leningrad ⁄ ⁄ ⁄ (h n ) in terms of replication in the lungs and noses of mice at and dpi. no virus was found in the brain tissue of immunized mice at and dpi (in undiluted samples tested). thus, it was shown that a ⁄ ⁄ mallard ⁄ netherlands ⁄ ⁄ (h n ), a ⁄ ⁄ cali-fornia ⁄ ⁄ (h n ) vaccine candidates are identical to a ⁄ leningrad ⁄ ⁄ ⁄ (h n ) in lacking neuroivasive capacity, and all three viruses similarly fail to replicate in the brain. it was shown that all immunized animals survived after challenge with wild-type a ⁄ mallard ⁄ netherlands ⁄ ⁄ (h n ) virus. the mice in vaccine groups showed no signs of morbidity. average weight changes were tracked from day to day in all study groups, but the changes did not exceed %. as shown in figure , the challenge virus actively replicated in respiratory tissue taken from mock immunized animals ( ae lgeid in the lung and ae lgeid in the nose), but failed to infect the brain and spleen. on the other hand, in both h n laiv vaccinated groups, all tested organs were free from presence of challenge virus. thus, immunization of mice with either mid or mid h n laiv protected the animals from the subsequent challenge infection with a homologous with wild-type h n virus. both h n and h n laiv candidates were found to be immunogenic. after one dose of mid of h n laiv, gmt of hi antibodies were ae . one dose of mid or mid h n laiv elicited hi antibody level with gmt of ae and ae , respectively. the second dose of h n laiv further stimulated serum hi antibody levels to gmt ae and ae , for mid or mid , respectively (data not shown). the mouse model is widely used to better understand the pathogenicity of avian influenza viruses for mammalian species, to be able to predict the pandemic potential of such viruses, and to develop improved methods for the prevention and control of the virus in a potential pandemic. a subset of the h viruses was evaluated for the ability to replicate and cause disease in balb ⁄ c mice following intranasal administration. h subtype viruses were able to infect mice without adaptation and manifested different levels of lethality and kinetics of replication. there is limited preclinical information available for laiv. thus, live monovalent vaccine against pandemic influenza virus h n (influvir) was tested for acute toxicity and its effect on the systems and organs of laboratory animals. according to toxicology and necroscopy results, the live monovalent influenza vaccine influvir, when applied intranasally, was safe and was well tolerated. in our current study we demonstrate that a(h n ) and a(h n ) laiv are indistinguishable from the parental mds virus with regards to replication kinetics in the upper and lower respiratory tract of mice. both h n and h n laiv candidates were immunogenic and protect mice against subsequent a challenge with the wild-type virus. live attenuated cold-adapted (ca) influenza vaccines are an effective means for the control of influenza, most likely due to their ability to induce both humoral and cellular immune responses. in our study we confirm that new h n laiv and h n laiv candidates are safe, immunogenic, and confer protection from influenza infection in mice. health organization (who) declared a pandemic by raising the worldwide pandemic alert level to phase . therefore, h n inactivated monovalent vaccine formulated with our proprietary oil-in-water emulsion based adjuvant was evaluated in ferrets for its potential to induce with low antigen dose efficient, robust, and rapid protective immunity against a wild type challenge virus (a ⁄ netherlands ⁄ ⁄ ). this adjuvant was also tested in ferrets in a h n avian influenza model for its ability to induce a cross-clade immunity and cross-protection. two independent studies (a&b) were carried out with male and female outbred ferrets (musleta putorius furo) in compliance with ''guide for the care and use of laboratory animals,'' ilar recommendations and aaalac standards. ferrets used in both studies were influenza seronegative by anti-nucleoprotein elisa and by hi assay against the pandemic and seasonal strains. in study a, four groups of seven ferrets aged approximately of months received one or two im vaccinations weeks apart of either af -adjuvanted ( ae lg of ha with af ) or unadjuvanted ( body weight loss was monitored as an indicator of disease and a mean body weight loss of % was recorded in the control group at day of necropsy. body weight loss was reduced to £ % and £ % in animals that had received and doses of either unadjuvanted or af -adjuvanted vaccine, respectively. viral lung titration showed high levels of virus replication ( ‡ ae tcid ⁄ g tissue) in the lungs of all control ferrets days after challenge. one or two administrations of unadjuvanted vaccine reduced lung viral load by and log , respectively. interestingly, ferrets that received either one or two doses of af -adjuvanted h n vaccine, showed significantly greater reduction of lung viral loads (> log ). no virus was detected in the lungs of ⁄ ( %) animals immunized with a single injection of the af -adjuvanted vaccine and in % of ferrets vaccinated twice. assessment of viral shedding from the upper respiratory tract showed that the af -adjuvanted a ⁄ h n monovalent vaccine was able to reduce the viral load in the nose and in the throat by ae and ae log , respectively, as compared to the control group. conversely, viral loads were only slightly reduced in the nose and mostly unchanged in the throat in ferrets immunized with either one or two doses of unadjuvanted a ⁄ h n monovalent vaccine. gross pathology and histology examinations revealed lung lesions consistent with influenza a ⁄ h n virus infec- however, a second dose of af -adjuvanted vaccine strongly increased hi and mn titers, which persisted for months (table ). antibody responses cross-reactive to heterologous clade . strain were elicited ferrets vaccinated with the af -adjuvanted clade . vaccine. hi antibody titers ‡ crossreactive to clade . and persistent up to d were observed in vaccinated animals. an inter-clade low crossreactive hi response to a clade strain was only detected in a few ferrets that had been vaccinated with the af -adjuvanted clade . . all af -adjuvanted clade . antigen vaccinated animals survived challenge either with the homologous or heterologous virus until euthanized day . after challenge, mean body temperature and mean body weights were monitored as indicators of disease. in the control ferrets, mean body temperature increased by - °c (depending on the challenge virus strain) h post challenge, with an accompanying mean body weight loss ranging from ae % to ae %. ferrets vaccinated with the af -adjuvanted clade . vaccine showed a lower and delayed fever compared to control ferrets that received the same viral challenge, whereas no significant differences were observed between vaccinated animals and their respective controls upon challenge with clade . or clade viruses. body weight loss was reduced in all vaccinated animals when compared to controls after challenge with either the homologous clade . strain or with one of the heterologous strains. lung virus titration showed high levels of virus replication in all control animals days after homologous challenge with the clade . virus. lung viral loads of all ferrets immunized with the af -adjuvanted clade . vaccine were reduced more than log . vaccination resulted in complete viral clearance from the lungs of % of animals assessed days after challenge. as compared to controls, a reduction of the mean viral load of about log was observed in ferrets vaccinated with the af -adjuvanted clade . vaccine after heterologous challenge with either the clade or clade virus. conversely, vaccination with af -adjuvanted clade . vaccine did not result in reduction of lung viral loads after challenge with the clade . heterologous virus strain. titration of pharyngeal swabs showed high levels of viral shedding in all control ferrets after challenge with clade . strain, whereas virus was not detected in any vaccinated animal. similarly, log reduction of viral shedding was seen in vaccinated versus control ferrets following clade heterologous challenge. lower reductions in viral shedding were observed after clade . challenge ( ae log ) and clade challenge ( ae log ). gross pathology and histology revealed lung lesions consistent with influenza a ⁄ h n virus infection all control animals challenged with the clade . , clade . or clade strains. mild to moderate lung lesions were observed in control animals following challenge with clade virus. macroscopic evaluation (percentage of affected lung parenchyma) and histopathological analysis (extent and severity of alveolitis, alveolar oedema and hemorrhage) showed that lung lesions were significantly reduced in af -adjuvanted clade . vaccinated animals after challenge with the homologous clade . virus strain as compared to controls. similarly, a reduction of the macroscopic and microscopic lung lesions was observed in vaccinated animals upon heterologous challenge with clade . and clade virus strains, whereas no differences were observed between control and vaccinated animals after challenge with clade virus. the results of these ferret challenge studies demonstrated that low doses of pandemic influenza vaccines formulated with an oil-in-water emulsion adjuvant, af , elicited strong antibody responses specific to the immunizing strain. importantly, these vaccines provided protection after homologous challenge with complete virus clearance in ferret lungs and reduced viral shedding from the upper respiratory tract suggesting an ability to reduce virus transmission. moreover, af -adjuvanted h n vaccine can provide cross-protection upon challenge with different h n clades by preventing mortality and reducing the viral burden in the lower and the upper respiratory tract. in conclusion, the results of these studies highlighted the ability of af -adjuvanted influenza vaccines to induce potent immune responses and full protection in ferrets against homologous challenge and suggested that protection may be mediated, at least in part, by antigenspecific humoral immunity. since , outbreaks of h n influenza virus infection in poultry have occurred in eurasian countries. phylogenetic and antigenic analysis of h n isolates revealed that there are three sublineages, consisting of g , g , and korean, among ha genes of the eurasian h n viruses. h n viruses do not cause severe disease in poultry, but co-infection of h n viruses with bacteria such as staphylococcus aureus, haemophilus paragallinarum, or attenuated coronavirus vaccine may exacerbate the disease. , h n viruses were isolated from domestic pigs in china and korea and from humans with febrile respiratory illness in hong kong in kong in , kong in , and it is, thus, postulated that in the present study, h virus strains were analyzed antigenically and phylogenetically to select a proper h n vaccine strain. inactivated whole virus particle vaccine was prepared, and its potency against h virus challenge was assessed in mice. viral rnas were extracted from the allantoic fluid of chicken embryos infected with viruses by using a commercial kit (trizol ls reagent; invitrogen, california, usa) and reverse-transcribed with the uni primer and m-mlv reverse transcriptase (invitrogen). the primers used for the ha gene amplification were h - f and h - r. for phylogenetic analysis, sequence data of the genes together with those from public database were analyzed by the neighbor-joining method. h influenza viruses were analyzed by hemagglutinationinhibition (hi) test. chicken hyperimmunized antisera against seven h viruses were prepared according to previous report. virus replication and pathogenicity against embryonated chicken eggs viruses were inoculated into -day-old embryonated chicken eggs and incubated for hours at °c. ha titers and % egg infectious dose (eid ) were measured every hours post-inoculation. pathogenicity of dk ⁄ hok ⁄ ⁄ against embryonated chicken eggs was evaluated by mean death time (mdt) as described previously. dk ⁄ hok ⁄ ⁄ was injected into the allantoic cavities of -day-old embryonated chicken eggs and propagated at °c for hours. the virus in the allantoic fluids ( ha) was purified by differential centrifugation and sedimentation through a sucrose gradient according to previous report. the concentration of protein was measured by od using ultrospec pro (amersham biosciences, tokyo, japan). the purified virus was inactivated with ae % formalin at °c for days. immunization of mice and challenge of immunized mice with hk ⁄ ⁄ four-week-old female balb ⁄ c mice were purchased from japan slc, inc. (shizuoka, japan). the mice were injected subcutaneously with , , ae , or ae lg proteins of inactivated dk ⁄ hok ⁄ ⁄ whole virus vaccine. two weeks later, the mice were boosted by subcutaneous injection with the same dose of the vaccine. control mice were injected with pbs. serum samples were tested by enzyme-linked immunosorbent assay (elisa) according to previous report. one week after the second vaccination, mice in each group were challenged intranasally with ll of ae eid of hk ⁄ ⁄ under anesthesia. on days postinfection, five mice in each group were sacrificed, and the lungs were separately homogenized to make a % (w ⁄ v) suspension with minimal essential medium (nissui, tokyo, japan). the virus titers of the supernatants of lung tissue homogenates were calculated in -day-old embryonated chicken eggs and expressed as the eid ⁄ gram of tissue. the other five mice in each group were monitored for body weight for days after challenge. the ha genes of h viruses were sequenced and analyzed by the neighbor-joining method. all of the h viruses were classified into the eurasian lineage ( figure ) . eleven, seven, and four strains were classified in the korean, g , and g sublineages, respectively. the h viruses of the korean and g sublineages were isolated from waterfowl, poultry, pigs, and humans in the east asian countries, and those of the g sublineage were isolated from poultry in the west asian countries. the cross-reactivity between these antisera and h n viruses were analyzed by hi test. the antisera against h viruses belonging to the korean sublineage were broadly cross-reacted to h viruses belonging to the g and g sublineages. h viruses belonging to the korean lineage were reacted to the antisera against h viruses belonging to the g and g sublineage compared with h viruses belonging to the other sublineage (data not shown). thus, it was suggested that h vaccine strain should be selected from the viruses of korean sublineage to prepare for the vaccine strain of h viruses. dk ⁄ hok ⁄ ⁄ replicated efficiently in -day-old embryonated chicken eggs (data not shown). pathogenicity of dk ⁄ hok ⁄ ⁄ against embryonated chicken eggs was determined by mdt. dk ⁄ hok ⁄ ⁄ was low pathogenic against embryonated chicken eggs (data not shown) and was selected as an h vaccine strain. to assess the potency of the vaccine against h virus infection, mice vaccinated subcutaneously with inactivated dk ⁄ hok ⁄ ⁄ were challenged intra-nasally with hk ⁄ ⁄ . immunogenicity of the inactivated vaccine was assessed by measuring the igg antibodies in mouse sera by elisa. antibody was detected in the group of mice injected lg protein after the first immunization and detected in the group of mice injected lg protein after the second immunization. thus, potency of the present inactivated whole virus vaccine was demonstrated in mice. next, to assess the protective immunity of the inactivated vaccine in mice, viral titers in the lungs was determined. the virus titers in the lungs were ae - ae eid ⁄ g in the groups of mice injected , and lg protein, and ae - ae eid ⁄ g in the other vaccinated groups. body weight reduction of mice were observed in the group of mice injected ae , ae lg protein, and control groups from dpi, and reached to % body weight loss from -to -day post-infection ( figure ). this result correlates with antibody titer in mouse sera and viral titers in the lungs. these results suggest that the test h inactivated whole vaccine confers prevent of weight loss and reduction of virus replication against h influenza virus infection in mice. recently, h n viruses of all of three sublineage have been isolated from wild birds and poultry in worldwide. h n viruses were isolated from pigs and humans in china and korea, suggesting that h n virus would be a potential for a pandemic influenza virus in human population. h n viruses were isolated from pigs in china and korea and were classified into the g and korean sublineage. in human cases, all h n virus isolated from humans in china was classified into the g sublineage. it was suggested that h n viruses isolated from pigs and humans vary in antigenicity of isolates between the korean, g , and g sublineages. therefore, it is important for the preparedness of influenza pandemic to develop h influenza virus vaccine, which could broadly cross-react to antisera of all sublineage viruses. so, we selected the vaccine candidate strain, dk ⁄ hok ⁄ ⁄ , which could broadly cross-react to antisera of all sublineage viruses, and which could replicate in this study, it was suggested that the test vaccine has potency to protect against challenge with h virus using mice for mammalian model. the challenge virus, hk ⁄ ⁄ , was isolated from human, replicates efficiently in mice, and shows pathogenicity in mice. the test vaccine inhibited viral replication and body weight loss in mice. whole inactivated vaccine produced protective immunity, supporting our approach of using whole virus particles for vaccine development. furthermore, whole particle virus vaccine could induce igg and mucosal iga levels after intranasal vaccination with whole particle vaccine. the present results may facilitate the studies of the vaccine for future pandemic caused by h influenza virus in humans. tants to attempt to improve growth. to determine whether wild type h n pdm grew better in the novartis mdck suspension cell line (mdck pf) than in eggs, isolations from h n pdm positive clinical samples were attempted in both substrates. the isolation rate of h n pdm viruses was higher in mdck pf cells ( %) ( ⁄ ) compared to allantoically inoculated eggs ( %) ( ⁄ ) . however the yields were lower than observed with seasonal viruses. little improvement in virus yield was seen with extra passaging or dilutions of h n pdm viruses isolated in mdck pf cells. with the emergence of the swine-origin pandemic h n (h n pdm) influenza in april , the need for efficient production of a suitable vaccine was a high priority. virus isolates were distributed by the who for the urgent development of suitable vaccine strains early in the pandemic. vaccine viruses can be grown in embryonated chicken eggs or in certified mammalian cells. , unfortunately wildtype h n pdm virus strains distributed by the who grew poorly in cell lines and eggs, requiring the generation of a series of conventional and reverse genetics derived reassortants to attempt to improve growth. from these reassortants, only the conventional egg derived reassortants nymc-x- a and nymc-x- (both based on one of the earliest known viruses a ⁄ california ⁄ ⁄ ) showed high enough growth and yield in eggs and cell culture to make them suitable for vaccine manufacture. these reassortants, while acceptable, still only gave haemagglutinin (ha) yields of approximately % that of seasonal h n reassortants. to determine if more recent wild type h n pdm viruses grew better in the novartis mdck suspension cell line (mdck pf), h n pdm positive clinical samples were cultured in mdck pf cells and also in embryonated hen's eggs. in addition, to improve virus yields from mdck pf isolates, extended passaging of three wild type h n pdm influenza viruses was performed using various virus dilutions at each passage level. the results were assessed using various serological and molecular biology techniques and compared to viruses isolated in eggs and conventional mdck cells. h n pdm viruses were received at the centre from who national influenza centres, who influenza collaborating centres and other regional laboratories and hospitals in australia, new zealand, and the asia ⁄ pacific region. viruses were received as original clinical specimens consisting of nasal swabs, throat swabs, nasopharyngeal aspirates, or nasal washes that had previously been shown to be h n pdm positive by real time rt-pcr. these specimens were then cultured in mdck pf cells with serum free medium containing trypzean (optaflu) and also independently inoculated into the allantoic cavity of day-old embryonated hen's eggs. virus cultures in mdck pf cells were sampled at and hour and evaluated by various means including ha titres. at hour, virus cultures were further passaged at varying dilutions ranging from ) to ) up to a total of passages. embryonated hen's eggs were incubated at °c for days and allantoic fluid was harvested and ha titres performed to determine whether a further passage was required in order to improve growth. the conventional reassortants were produced by a mixed infection of eggs or mdck pf cells with the wild type virus and a donor virus carrying the internal genes of the a ⁄ puerto rico ⁄ ⁄ virus. the reassortants were obtained by sequential passages using immuno-selective antisera against the surface antigen of the donor virus to remove virus populations carrying the ha and na protein of the donor strain. the reverse genetics viruses were rescued in vero cells using the plasmid system. both types of reassortants were generated and supplied by who collaborating centres and essential regulatory laboratories except the nvd-c- strain, which was produced by novartis. in this small study with recent h n pdm viruses, the isolation rate was higher in mdck pf cells ( %) ( ⁄ ) compared to allantoically inoculated eggs ( %) ( ⁄ ) . assessment of ha titres, however, showed higher ha titres in egg-isolated viruses compared to viruses isolated in mdck pf cells after two passages. egg generated or cell generated reassortant viruses gave higher ha titres compared to the homologous wild type viruses (table ) . no amino acid changes were observed in mdck pf isolated influenza viruses compared to original specimens or viruses isolated in conventional atcc derived mdck cells, unlike egg isolated viruses which showed a number of amino acid changes, many consistent with egg adaptation mutations (table ) . viruses isolated in mdck pf cells grouped phylogenetically with viruses isolated in conventional atcc derived mdck cells or viruses sequenced from original clinical samples, while egg isolated viruses grouped slightly differently (data not shown). as a result of the poor growth of h n pdm viruses in mdck pf cells, serial dilutions were performed over a number of passages ( figure ). based on the results obtained from the virus isolates, a ⁄ victoria ⁄ ⁄ , a ⁄ wellington ⁄ ⁄ , and a ⁄ darwin ⁄ ⁄ , a supplemental protocol was developed and used in the isolation of a ⁄ brisbane ⁄ ⁄ (figure ). only small differences in ha titer were seen between different dilutions, and copy number showed a similar trend to ha titer at each passage ( figure ). following the supplemental protocol for the isolation of a ⁄ brisbane ⁄ ⁄ results showed slightly higher ha titres with little variation between passages. the egg derived reassortants nymc-x- a and nymc-x- were also assessed for growth in mdck pf cells and were found to be superior by ha titer to other conventional reassortants (egg or cell derived), reverse genetics derived reassortants, or wild type viruses (table ) . two methods were used to determine the ratio of ha to other viral proteins: densiometric analysis using sds-page and reversed-phase hplc using a subtype specific standard. ha content in different vaccine seeds of influenza a subtypes demonstrated that the ha content per total virus protein from the nymc h n pdm reassortants was significantly different to the seasonal influenza a subtypes. for the seasonal h n the ratio of ha to p p p p p p p p p p p p p p p p n and m was ‡ %, for the h n the ratio of ha to n and m was £ %, while for the pandemic a ⁄ h n , the ratio of ha to n and m was much lower at £ % (data not shown). the results of this study has observed the growth of a series of - h n pdm viruses in vaccine suitable mdck pf cells to be generally lower than what has been seen with other seasonal influenza viruses. little improvement in virus yield was seen with extra passaging of h n pdm viruses isolated and passaged in mdck pf cells. passaging up to times in mdck pf cells using dilutions ranging from ) to ) resulted in supernatants with viral ha titres ranging from ha ⁄ ll to ha ⁄ ll. the isolation rate of h n pdm viruses was higher in mdck pf cells ( %) compared to allantoically inoculated (and passaged) eggs ( %), a trend also seen in previous work with seasonal influenza viruses. in contrast a study by hussain and colleagues found similar rates of isolation and replication of seasonal influenza viruses in mdck cells and eggs. the virus load as determined by matrix gene copy number showed a similar trend to ha titers. two of the isolates exhibited small rises and falls in ha titer during passaging, while a third, a ⁄ victoria ⁄ ⁄ gave consistently higher titers. interestingly this virus was unable to be isolated in eggs. the ha sequences of all strains were assessed at p , p , p , p , p and when available compared to the original clinical sample ha sequence. mdck pf-isolated viruses had few if any changes in their ha amino acid sequence, while the majority of egg isolates showed - amino acid changes compared to the clinical sample, with an egg adaption change (l i) evident in a number of them. the ha sequence of one of the better growing viruses, a ⁄ victoria ⁄ ⁄ , was found to have a g e change compared to the a ⁄ california ⁄ ⁄ reference virus. this change was also seen in the virus isolated in conventional, adherent mdck cells. these viruses with g e change when tested by hai have shown reduced reactivity with ferret antisera to a ⁄ california ⁄ ⁄ -like viruses, but normal reactivity with ferret antisera to h n pdm a ⁄ bayern ⁄ ⁄ -like viruses. despite this mutation all mdck pf derived viruses appeared to be a ⁄ california ⁄ ⁄ -like by hai. the h n pdm egg-derived reassortants (nymc x- a and nymc x- ) when grown in mdck pf cells were superior to wild type h n pdm viruses, reverse genetics derived reassortants, and other egg-derived reassortants. the yields of haemagglutinin from the nymc h n pdm reassortants were still below those seen with sea-sonal h n reassortants as was also seen in eggs. this trend has also been noted in other studies. in summary, attempts to improve growth and yield of the h n pdm wild types for mdck pf cells by extended passaging were not successful, and reassortants did not perform as well as seasonal h n reassortants have in the past. however, using higher dilutions for the passaging of h n pdm viruses in mdck pf cells did result in higher ha titres (a ⁄ brisbane ⁄ ⁄ ). further work is therefore required to generate pandemic h n seed viruses that grow well in a variety of cell culture and egg based vaccine production systems. the aim of this study is to evaluate antibody response to influenza virus neuraminidase (na) following immunization with live attenuated influenza vaccine (laiv). we adjusted the peroxidase-linked lectin micro-procedure previously reported by lambre, et al. ( ) to assay neuraminidase inhibition (ni) antibody in sera taken from immunized mice and from human subjects in a clinical trial. for the assay, we prepared the a(h n ) reassortant virus containing the na of a ⁄ california ⁄ ⁄ (h n ) and the hemagglutinin (ha) of a ⁄ equine ⁄ prague ⁄ ⁄ (h n ). in addition, we used an na-specific igg elisa assay to test sera from immunized mice and volunteers. in mice, one dose of laiv induced ni antibody of a geometric mean titer (gmt) of ae , compared to ae in the control group. gmt of ni from human subjects who received two doses of pandemic a(h n ) were significantly higher than pre-vaccination titers. in unvaccinated human subjects, na-specific cross-reactive antibodies to pandemic a(h n ) were detected more often than cross-reactive antibodies to ha. antibody response to influenza virus na contributes to the overall immune response to influenza and may provide partial protection against influenza infection and reduce severity of disease in the host. a number of preclinical studies using purified or recombinant na have shown that various two-dose vaccine regimens in mice may significantly reduce pulmonary virus titers following viral challenge. [ ] [ ] [ ] a plasmid dna-vaccine model demonstrated cross-reactive antibodies to human n in mice could provide partial protection against a lethal challenge against h n or recombinant pr bearing the avian n . immunogenicity of current influenza vaccines, including laivs, is measured primarily as a level of strain-specific hemagglutination inhibition (hi) antibodies. however, the who meeting on the role of na in inducing protective immunity against influenza infection ( ) specified a need to develop suitable assays for anti-na antibody detection to enhance influenza vaccine evaluation in preclinical and clinical studies. the aim of the current study was to evaluate anti-na antibodies to pandemic a(h n ) influenza virus following laiv immunization. the rn ⁄ -swine a(h n ) reassortant influenza virus containing the na of a ⁄ california ⁄ ⁄ (h n ) and the ha of a ⁄ equine ⁄ prague ⁄ ⁄ (h n ) generated by classical genetic reassortment in embryonated chicken eggs (ce). parental a ⁄ equine ⁄ prague ⁄ ⁄ (h n ) influenza virus was obtained from the center for disease control and prevention, atlanta, ga, usa. viruses were propagated in day old ce and purified by sedimentation out of the allantoic fluid, followed by ultracentrifugation on - % sucrose step gradient. for the mouse studies, week old cba mice were inoculated intranasally with one dose eid ⁄ ae ml of a ⁄ ⁄ california ⁄ ⁄ (h n ) vaccine strain or received ae ml pbs. blood samples were collected on day post inoculation. healthy young adults were immunized twice, or days apart in the fall with a ⁄ ⁄ california ⁄ ⁄ (h n ) laiv manufactured by microgen, irkutsk, russia. for the human studies, peripheral blood specimens were collected from volunteers before vaccination, days after the first vaccination, and days after the second dose of vaccine. sera from five subjects diagnosed with influenza a(h n ) were collected in december , to weeks post infection and kindly provided by e. vo ıtsekhovskaia from biotechnology laboratory, institute of influenza, rams. also, sera obtained in from unvaccinated vol-unteers were tested for presence of cross-reactive antibodies to a ⁄ california ⁄ ⁄ (h n ). sera were treated with a receptor-destroying enzyme from vibrio cholera (denka-seiken, tokyo, japan) and then were tested in duplicates for hemagglutination-inhibition (hi) h specific antibodies by standard procedures using a ⁄ ⁄ california ⁄ ⁄ (h n ) test antigen. the peroxidase-linked lectin micro-procedure previously reported by lambre, et al. was adjusted to assay ni antibody. briefly, -well plates (sarstedt, inc., nümbrecht, germany) were coated overnight with ll of lg ⁄ ml fetuin. the purified a(h n ) reassortant virus was diluted in pbs with % bsa and mm ca + to give a four times higher optical density at nm (od ) compared to control wells not containing virus. fifty-microliter volumes of serially diluted serum samples were incubated with an equal volume of prediluted virus for hour at °c. after incubation, the plates were washed and neuraminidase activity was measured by subsequently adding peroxidase-labeled lectin ( lg ⁄ ml; sigma, st. louis, mo, usa), incubating for hour at room temperature, washing the plates, and adding ll of peroxidase substrate (tmb). the reaction was stopped after minute by adding ll of n sulfuric acid. od values were measured at nm using the universal microplate reader (el x ; bio-tek instruments, inc., winooski, vt, usa). the ni titers were expressed as the reciprocal dilution that gave % od of positive control (virus, no serum control). in addition we used an igg elisa assay with ae lg ⁄ ml of purified na from a ⁄ california ⁄ ⁄ (h n ) to test sera from immunized mice and volunteers. data were analyzed with statistica software (version ae ) (statsoft, inc. tulsa, oklahoma, usa). geometric mean titers (gmt) were calculated and used to represent the antibody response. the comparisons were made within groups between pre-and postvaccinated titers (expressed as log ) after first and second vaccination using wilcoxon matched pairs test. to compare multiple independent groups we used a kruskal-wallis anova with subsequent multiple pairwise comparison based on kruskal-wallis' sums of ranks. a p-value of < ae was considered to be statistically significant. in mice, one dose of laiv induced antibody responses to both ha and na components of the a ⁄ california ⁄ ⁄ (h n ) influenza virus vaccine (table ) . geometric mean titers of ni antibody levels from vaccinated mice were ae and were significantly higher compared to those in unvaccinated control animals (p < ae ). elisa igg titers expressed as log were ae compared to ae in control group. there was good correlation between antibody rises obtained using ni or elisa tests (r = ae ). in a study during the fall of , % of examined unvaccinated subjects were negative to pandemic a(h n ) (hi titers £ : ). serum hi antibody titers to pandemic a(h n ) ‡ : were considered to be protective against *the postvaccination gmts of hi antibodies after revaccination were higher than respective prevaccination titers (p = ae ) **the postvaccination gmts of ni antibodies after revaccination were higher than respective prevaccination titers (p = ae ) serum hi and ni antibodies to a ⁄ california ⁄ ⁄ (h n ) after one or two doses of pandemic laiv were evaluated in subjects who had pre-vaccination hi titers £ : ( table ) . post-vaccination gmts of a(h n )-specific antibodies were significantly higher than pre-vaccination titers only among subjects who received two doses of laiv ( table ). the frequency of subjects with ‡ fourfold rises in hi antibody titers was higher after two doses ( ae %) compared to responses after one dose ( ae %) although the differences were not statistically significant ( table ). the highest antibody titers of hi and ni antibodies were achieved after natural infection (p < ae compared to all post-vaccination groups). all five subjects with confirmed influenza also had high levels of n -specific igg measured by elisa using purified na as the coating antigen (data not shown). influenza ha and na surface proteins are primary targets of neutralizing antibodies that provide protection against influenza infection. the correlation of strain-specific hi antibody titers ‡ : to protection of % of the subjects against influenza infection is based on a number of reports published in s. serum antibodies against viral na as result of influenza infection or vaccination also can neutralize the virus from infecting cells; however, little is known about protective levels of such antibodies. to evaluate ni antibodies directed against pandemic a(h n ) we used the reassortant a(h n ) influenza virus with mismatched ha to avoid non-specific inhibition. we demonstrated laiv immunization effectively increased levels of ni antibody, although in smaller amounts compared to influenza infection. our data suggest that an antibody to neuraminidase, resulting from an earlier infection of the circulating seasonal influenza a(h n ), evidently cross-reacted with the n of pandemic influenza virus, perhaps due to the previously reported % of conserved na epitopes in pandemic a(h n ). the peroxidase-linked lectin test using the reassortant a(h n ) influenza virus was shown to be a sensitive and time effective means of revealing homologous and cross-reactive anti-na antibodies after laiv immunization or influenza infection. this could be a useful method for influenza vaccine evaluation. significant levels of anti-na antibodies detected in peripheral serum from subjects infected with wildtype h n virus or with h n laiv. and the cross-antibody response to ph n . for calculation of geometric mean titer (gmt), a titer of < was assigned a value of . statistical significance was determined by paired t-test. cross-reactive antibody response to ph n in vaccinated populations of seasonal influenza virus table shows the antibody response to seasonal influenza viruses and ph n of participants. before vaccination, no or little antibody response to ph n had been detected in all age groups. vaccination with seasonal influenza vaccines resulted in seroresponse in over % of subjects, except children aged - years ( %) and subjects aged of - years ( %) vaccinated with - season influenza vaccine and adults aged ‡ years ( %) vaccinated with - season influenza vaccine. seroconversion was detected in over % of subjects of all ages. postvaccination to prevaccination gmt ratios for response to seasonal influenza viruses was more than ae -fold. in contrast, seroresponse to a ⁄ california ⁄ ⁄ after vaccination with - and - seasonal influenza vaccines were detected in only % and % of those aged - years, % of those aged - years, % and % of those aged - years, % and % of those aged ‡ years, respectively. seroconversion in all participants ranged from % to %, and postvaccination to prevaccination gmt ratios were < ae -fold. preexisting antibody response to ph n among subjects born before s in china according to a recent report, people who were born from to had a preexisting immunity to ph n . although only a very low level of cross-reactive antibody response to ph n had been observed among older subjects aged more than years old in china, we further analyzed these data by different age distribution of subjects, which can trace back to the previous infection that is genetically and antigenically more closely related to this new ph n influenza virus. the proportion of seroresponse to ph n with the titer of , , and (highest titer detected from participants of all ages in this study) and the value of gmt were analyzed according to the birth decade of subjects from . similarly, a peak of antibody response and the value of gmt occurred both in subjects born from to and sharply decreased afterward ( figure ). the seroresponse of subjects born in and before is significantly higher than subjects born afterward (p < ae ). similar to recent studies in some asia countries (guangxi province of china and singapore), limited antibody response to ph n had been detected in children and adults. , but, some other studies from european countries (finland, germany, the united kingdom) and the united states reported a high proportion of older individuals aged > years with pre-existing cross-reactive antibodies to ph n , which may possibly ba a result of previous exposure to antigenically related h n influenza viruses circulating in earlier decades or a lifetime of exposure to influenza a, which has resulted in broad heterosubtypic immunity among older individuals in those countries. previous infection and vaccination with a ⁄ new jersey ⁄ may also contribute to the high level of cross-reactive antibody response to ph n among adults older than years in the us. , the peak of the antibody response to ph n in subjects born between and , which is consistent with recent reports, may suggest the previous viral infections of spanish flu or closely related influenza viruses, which is before and little after the year of . recent antigenic report of new ph n viruses indicated that they are antigenically homogeneous among historical viruses, which are most similar to classical swine a(h n ) viruses. a number of reviews [ ] [ ] [ ] [ ] confirmed that the virus is the likely ancestor of all four of the human and swine h n and h n lineages, as well as the 'extinct' h n lineage. in , a(h n ) influenza viruses were first isolated from swine. they have been shown to be antigenically highly similar to the recently reconstructed human a(h n ) virus. the cellular responses may contribute to the sustaining and long term antibody response. probably, boosting by persisting antigenically related viruses in the early decades of the th century, may have contributed to the ability of these subjects to sustain memory b cells, and it is well established that a subset of plasma cells is long-lived, and these cells contribute to durable humoral immune responses, such as that observed after childhood smallpox vaccination. furthermore, t cells that recognize cross-reactive epitopes are preserved and might be enriched in the memory population; the course of each infection is influenced by the t-cell memory pool that has been laid down by a host's history of previous successive infections. our study indicated that wide transmission of this new virus or any antigenically close related influenza a(h n ) viruses may not have circulated among populations in china before the outbreak of ph n . our data also suggests the need for vaccination with ph n vaccine in all age groups. hypo-and agammaglobulinemia patients have an impaired immune system and are particularly susceptible to bacterial infections that are normally defended against by antibodies. therefore, patients routinely receive replacement therapy with immunoglobulins isolated from healthy blood donors. these patients are also prone to get viral infections, possibly due to defects in toll-like receptors and . because these patients lack an antigen specific humoral immune response, they are rarely vaccinated. the ability of hypogammaglobulinemic patients to produce a specific cell-mediated immune response upon vaccination has only been sparsely investigated. in contrast to local mucosal antibodies, vaccine-induced cell-mediated immunity is not believed to protect against pathogen entry per se, but may be sufficient to provide protection against severe disease and death following transmission of some microbes. , the aim of this pilot study was to investigate if influenza vaccination of hypogammaglobulinemic patients can induce an influenza-specific cell-mediated immune response. we therefore vaccinated hypogammaglobulinemic patients and healthy controls with pandemic h n virus vaccine and subsequently investigated the bcell and t-cell responses. the percentages of ifn-c, il- , and tnf-a cytokine producing cd + th -cells were determined, as these cytokines are important indicators of cell-mediated immunity. five a-or hypogammaglobulinemic patients were classified based on the freiburg classification : patient # is diagnosed with x-linked agammaglobulinemia, patient # and # are in group ia, patient # is in group ib and patient # is in group ii. the monovalent egg grown split virus vaccine adjuvanted with as was manufactured by glaxosmithkline (gsk), belgium. the vaccine strain was produced by reassortment between influenza a ⁄ california ⁄ ⁄ (h n ) and a ⁄ pr ⁄ ⁄ (h n ) to produce a ⁄ california ⁄ ⁄ -like virus (x a). the vaccine was mixed with adjuvant to contain ae lg haemagglutinin (ha) of a ⁄ california ⁄ ⁄ -like virus (h n ), squalene ( ae mg), dl-atocopherol ( ae mg), and polysorbate ( ae mg) per ml. healthy controls and hypogammaglobulinemia patients were vaccinated by intramuscular (im) injection. hypogammaglobulinemia patients received one or two vaccine doses days apart. the intention was to vaccinate the hypogammaglobulinemic patients with two doses of ae lg ha, but ae lg ha was inadvertently administered to the patients as the first dose. for patient # this was the second dose as he had received an initial dose of ae lg ha months prior to the study. patient # , # , and # received a second dose of ae lg ha. four healthy controls were immunised with one dose of ae lg ha according to norwegian national guidelines. peripheral blood mononuclear cells (pbmcs) were harvested and washed in pbs with % fbs. the pbmcs were resuspended in lymphocyte medium (rpmi with l-glutamine, ae mm non-essential amino acids, mm hepes ph ae , mm sodium pyruvate, iu ⁄ ml penicillin, lg ⁄ ml streptomycin, ae lg ⁄ ml fungizone and % fbs) prior to use in the enzyme-linked immunospot (elispot) and influenza-specific cd + t-cell assays. serum haemagglutination inhibition antibodies were tested by a standard method using ha units and ae % turkey erythrocytes. all samples were tested in duplicate and the test was repeated at least two times. titres < were assigned a value of for calculation purposes. for numeration of antibody-secreting cells (asc), an eli-spot assay was conducted as previously described with the following modifications. ninety-six well elispot plates were coated with lg ⁄ ml of a ⁄ california ⁄ ⁄ like (x a) h n virus diluted in pbs overnight at °c. after blocking with rpmi ( % fbs), pbmcs were added and incubated ( °c, % co ) for hour. secreted antibodies were detected with biotinylated goat anti-human igg, iga and igm specific antibody (southern biotech, birmingham, alabama, usa), incubated for hour at room temperature and developed with extravidin peroxidase and aec substrate. the numbers of spots were counted using an elispot reader (immunoscanÔ) and immunospot Ò software. the influenza-specific cd + th -cell response was measured by intracellular cytokine production of ifn-c, il- , and tnf-a. peripheral blood mononuclear cells ( per well) were incubated for hour ( °c, % co ) in ll lymphocyte medium containing lg ⁄ ml anti-cd , lg ⁄ ml anti-cd d, ae lg ⁄ ml monensin, lg ⁄ ml brefeldin a, (bd biosciences, franklin lakes, new jersey, usa), and the h n influenza split virus vaccine x a (either ae lg ⁄ ml or lg ⁄ ml ha). basal cytokine production was determined by incubating pbmcs in lymphocyte medium without influenza virus, and the percentage of cytokine positive cells without influenza stimulation were subtracted from influenza-stimulated cells. cells were stained for cd , cd , cd , ifn-c, il- , and tnf-a (bd biosciences) as previously described. finally, cells were resuspended in pbs containing % fbs and ae % sodium azide and analysed by bd facscanto flow cytometer ( - cells acquired). flowjo v ae ae (tree star, ashland, oregon, usa) was used for data analysis. five to six fold lower gmts were found in the patient group as compared to the healthy controls throughout the study ( figure a) . the lowest hi titres were obtained in patients # , # , and # , whilst patients # and # and all healthy controls fulfilled two of three european medicines agency committee for medicinal products for human use (chmp) seasonal influenza vaccine licensing criteria, by obtaining an hi titre > and a mean geometric increase of ae between pre-and post-vaccination. thus, the hi data indicate that two vaccine doses was sufficient to induce a protective hi antibody response in two out of five of the hypogammaglobulinemia patients tested in this study. the numbers of influenza-specific iga, igg, and igm asc were tested pre-vaccination and days post-vaccination with the h x a virus. few or no ascs were detected pre-vaccination (data not shown). at days post-vaccination the patient's iga, igg, and igm asc levels were significantly lower (p < ae ) compared to the healthy controls ( figure b) . but, the post-vaccination asc numbers in the patients were generally higher than at pre-vaccination stage ( - ascs). patient # had the highest iga and igg asc numbers, followed by patients # and # , whilst patient # and # had few or no asc's. these results confirm that the patients are indeed hypogammaglobulinemic and that some of the patients (# and # ) could be agammaglobulinemic in the context of producing influenza-specific antibodies. the asc levels of patients # , # , and # were lower than those of the healthy controls, but could possibly be adequate for reducing the severity of influenza disease. the influenza-specific th -cell response was evaluated by stimulating pbmcs with the influenza x a virus , , and days post-vaccination. stimulation of healthy control pbmcs with x a days after vaccination, induced ifn-c, il- , and tnf-a production by an average of ae %, ae %, and ae % cd + t-cells, respectively. patient # and # had higher responses than the healthy controls and stimulation with x a induced ae %, ae %, and ae % of t-cells from patient # to produce ifn-c, il- , and tnf-a, respectively (figure a) . the response of patient # was further boosted by a second vaccine dose, which resulted in ae %, ae %, and ae % cd t-cells producing ifn-c, il- , and tnf-a, respectively at day ( figure b ). these results show that the hypogammaglobulinemia patients studied here did not have a common impaired influenza-specific cd + th cytokine response. rather, there was a tendency towards increased responses, suggesting that the diminished antigen specific b-cell responses could induce a compensatory antigen specific th -cell response. the results from this pilot study suggest that some hypogammaglobulinemia patients may benefit from influenza vaccination. we found very different patient responses to influenza vaccination, but some of the patients (patient # and # ) did mount low influenza-specific asc responses. in addition, the vaccine-induced hi antibody titres above the protective level in patient # and # . these results are in accordance with previous publications, which described that polypeptide vaccines induce humoral responses in subgroups of common variable immunodeficiency patients. [ ] [ ] [ ] in this study, we also investigated cell-mediated immunity and found the percentages of homologous and cross-reactive influenza-specific cd + th -cells to be in the same range (for patient # , # , and # ) or higher (for patient # and # ) in the a-or hypogammaglobulinemic patients compared to the healthy controls. the higher response is probably due to the patients having received a vaccine dose of ae lg ha, whilst the controls received ae lg ha. in addition, the patients received a second booster dose, which influences the day and months responses. nonetheless, these results are the first to demonstrate that proliferation of pandemic influenza antigen specific th cells can be induced in hypogammaglobulinemic patients. in addition, vaccination induced influenza-specific asc's in some patients. the findings are promising and provide hope that hypogammaglobulineamic patients could be vaccinated against influenza and other diseases preventable by figure . peripheral blood mononuclear cells s from patients and healthy controls were isolated at day (a), (b), and day (c) and stimulated for hour with x a virus before staining and flow cytometric analysis. the figure shows the mean ± sd frequency of influenza-specific cd + cytokine producing cells (%) where the basal cytokine production from unstimulated cells has been subtracted. data for the hypogammaglobulinemia patients are additionally shown as a number for each patient. **significantly higher frequency of il- producing cd + t-cells in the patients compared to the healthy controls (students t-test p < ae ). titres are presented as the geometric mean titre ± % confidence interval. elispot data (b) are presented as the mean number of influenza-specific iga, igg, and igm ascs per peripheral blood mononuclear cells ± sem. data for the hypogammaglobulinemia patients are additionally presented by a number for each patient. *significantly higher numbers of ascs were detected in the healthy controls as compared with the hypogammaglobulinemia group (students t-test, p < ae ). vaccination. however, this hypothesis should be tested in larger clinical studies. the influenza virus undergoes antigenic evolution under intense immune selection pressure from herd immunity in humans through the process called antigenic drift and shift. , because of antigenic drift, yearly updating of vaccine strain is needed. a mismatch between the circulating strains and the vaccine strain in the subsequent season is often encountered, resulting in reduction of vaccine effectiveness and lack of protection from the circulating strain. in order to address this, a universal influenza vaccine based on a more conserved part of the influenza virus, which is not affected by antigenic change and that is conserved across all strains, remains the ultimate goal to afford cross-protection to drifted strains as well as to other subtypes of influenza which may arise from antigenic shift. , previous studies have investigated the potential of the m e. , m e has remained highly conserved since it was first isolated in . several studies have examined the use of m e as a vaccine component, using various approaches including proteins, peptides, dna vectors, and attenuated viral vectors. , [ ] [ ] [ ] [ ] [ ] [ ] although m e is a weak antigen, by linking the protein to a carrier hepatitis b virus core particle, protection against influenza has been achieved in mice particularly when administered with an adjuvant. some articles found that vaccination with m e coupled to hbc induces protective antibodies, whereas the contribution of t cells to protection was negligible. protection induced by vaccination with m e-hbc was weak overall and failed to prevent weight loss in vaccinated infected animals, and mice succumbed to high dose infection. we aimed to address the poor immunogenicity of m e-hbc by using igv as adjuvant. igv domain is common and conserved in the tim family. ligand binding sites of t cell immunoglobulin mucin (tim) located at igv domain. [ ] [ ] [ ] tim function is done by anti tim antibody which recognized the ligand binding sites of igv domain. tim family members share a common motif, including an igv domain. they are differentially expressed on th cells and th cells with the ability to regulate the immune system. , the igv domain of human b - is sufficient to co-stimulate t lymphocytes and induce cytokine secretion. soo hoo et al. vaccinated with tim- antibody and inactivated influenza and found enhanced vaccine-specific immune response. we report here for the first time the use of igv recombinant protein as adjuvant to immunize mice with influenza m e-hbc. results indicated that igv can induce the strong cellular immune response and cross reaction with different subtype influenza virus antigen. target igv may be used to develop the new method for vaccination strategies. expression and purification of recombinant igv protein rna was extracted from healthy human pbmc. one-step rt-pcr (qiagen, valencia, ca, usa) was done for the amplification igv gene. the pcr product was purified and cloned into pet a (novagen, madison, germany). the resultant construct pet a-igv has a histidine (his) tag ( his) at the n terminus. dna sequence of the insert was determined by sequencing. igv. recombinant protein was expressed in escherichia coli and was purified on a ni column (novagen). the purified protein was examined by sds-page and western blotting. six-eight weeks female balb ⁄ c mice (institute of zoology chinese academy of sciences, china) was used for the study. mice were immunized twice intradermally with ug m e-hbc (provided by cnic, china) combined with different doses of recombinant igv protein , , ug, respectively, or without igv as control. the area proximal to the tibialis anterior muscle was sterilized with % ethanol and different groups of mice were injected bilaterally with , , ug igv plus ug m e-hbc in ul phosphate buffer saline per mouse using a ml syringe with attached ⁄ ¢¢ g needle. the immunization was given at weeks intervals. four blood samples were obtained from every mouse: before immunization, after the first and second immunization, and after virus challenge by retro-orbital plexus puncture. after clotting and centrifugation, serum samples were collected and stored at ) °c prior to use for assays. mouse-adapted a ⁄ pr ⁄ ⁄ (h n ), a ⁄ brisbane ⁄ ⁄ (h n ), a ⁄ xinjiang ⁄ ⁄ (h n ), and a ⁄ guangzhou ⁄ ⁄ (h n ) were provided by chinese national influenza centre. nine to eleven days old embroynated specific pathogen free (spf) chicken eggs were inoculated with virus, and the eggs were incubated at °c for - days. the allantoic fluid was collected and purified by sucrose density gradient centrifugation, and the virus was inactivated by formaldehyde at °c overnight. to identify igg, igg , igg a against m e, elisa assays were used. in brief, -well (nunc, brunei, denmark) were coated with ul ⁄ well of m e recombinant protein (provided by gene lab of ivdc, xuanwu district, beijing, china) in carbonate buffer (ph ae ) overnight at °c. immediately before use, the coated plates were incubated with blocking solution ( % bsa in pbs) for h at °c and washed four times with pbs containing ae % tween (pbs-t). the serum samples were serially diluted and added in the plates. the detection color was developed by adding hrp-labeled goat anti-mouse igg, igg , or igg a ( figure ) . no cross-strain response was observed in the control group. the igv adjuvented groups show splenocytes stimulation with seasonal h n , h n , h n , and h n antigens. m e-hbc immunization without igv showed splenocyte stimulation, but the extent was lower than animals immunized in the presence of the igv adjuvent. these data suggested that igv had enhanced effect on priming against the conserved viral antigen matrix protein and generation cross-strain immune response. influenza is a respiratory disease causing epidemics every year. h n viruses and swine-origin h n have also infected humans in recent years. seasonal influenza vaccine cannot cope with significant antigenic drift or with the emergence of pandemic viruses of different subtypes not contained in the vaccine. the high extent of conservation of the m e makes it a promising immunogen. a vaccine based on coupling of the m e peptide to an appropriate carrier may provide a universal vaccine with effectiveness and safety. m e based vaccination induces protective antibodies not only in mice, but also in ferrets and monkeys. the carrier hepatitis b core as carrier with m e forms a virus like particle (vlp). vaccination with m e coupled to hbc induces protective antibody, whereas the contribution of t cell protection was negligible. protection induced by vaccination with m coupled to hbc was weak overall. in order to improve the vaccination effect of m e-hbc, new adjuvant igv was evaluated in combination with the m e-hbc. the tim molecules are a recently discovered class of proteins with the ability to regulate the immune system. crystal structures of the tim molecules has revealed a unique, conserved structure with ligand-binding sites in the igv domain. to determine the potential immunostimulatory molecular properties of igv, we have evaluated immune response of the igv in combination with m e-hbc vlp. previous papers reported that vlp immunized mice can induce the th and th immune response. different adjuvant combined vlp can produce biased immune response th ⁄ th mixed immune response, or th -preferred th ⁄ th profile. thus, the response following the use of igv as a new adjuvant combined with m e-hbc vlp needs to be evaluated. results indicated that igv combined groups showed th biased immune response and enhanced cross reactive t cell immune responses. this may show that igv immunized the mice and antiigv antibody can cross link the igv on t cells and enhance the cell figure . t cell proliferation assay. mice were immunized twice with , , , ug ⁄ ml igv plus m e-hbc, respectively, and naive group was immunized with pbs. three weeks after a boosting immunization, spleens were harvested from immunized and naive mice. different subtypes of inactivated virus antigen (a) h n , (b) h n , (c) h n , (d) h n were added and cocultured with different group splenocytes for h. quick cell proliferation assay kit was used to detect the cell proliferation. the - nm absorbance was read on a plate reader. data were showed were shown as mean values. the difference between naive group and different doses igv plus m e groups was determined using the student's t-test. all significance level is p < ae . response. we also evaluated the cross-protection produced by igv combined m e-hbc. we challenge with mouseadapted strain pr and prove the cross protection via reaction between the cells from the immunized animal and different subtypes of virus antigen. some subtypes of virus cannot infect the mice naturally, and therefore, virus challenge cannot be used to evaluate the effect. we co-cultured the t cells with inactivated antigen h , h , h , and h , and t cell proliferation was measured. results indicated that after immunization with igv plus m e-hbc, the t cells show cross-protection with other subtypes. this provides evidence that igv can enhance the cross protection across subtypes. the results of this study demonstrated that recombinant igv can be useful as an adjuvant and polarize the m e-hbc vlp immune response to a th profile. igv induced the m e-hbc vlp to induce t cell proliferation and cross-reactive responses to different influenza virus subtypes. this finding represents a new direction for the promotion of cell mediated immunity in m e based vaccine against influenza. a core european protocol, i-move, describing the methods to estimate influenza vaccine effectiveness (ive) was proposed by the european centre for disease prevention and control (ecdc) and epiconcept for the - season. it includes a case control method for pooled analysis based on a randomized ''systematic'' sample of swabs. , collection of swabs using a non randomized, i.e., ''ad hoc,'' sampling strategy, left at the appreciation of sentinel practitioners, provides a greater number of cases and con-trols for ive estimation more easily than using a systematic randomized sampling strategy. the french grog (groupes régionaux d'observation de la grippe) early warning network collects more than specimens yearly from cases of acute respiratory illness (ari), using both sampling methods. , during the circulation of pandemic influenza viruses in france, it gave an opportunity to compare ive estimates using systematic randomized versus non systematic ''ad hoc'' sampling. influenza vaccine effectiveness was estimated by a casecontrol methodology according to ecdc i-move protocol, using on the one hand a systematic random sampling, on the other hand ''ad hoc'' non random sampling. the study was proposed to primary care practitioners of the grog network ( general practitioners and pediatricians) trained to collect data and swabs. the study population was patients from the community of all ages consulting a grog practitioner for an influenza like illness (ili) and having a nasal or throat swab taken within an interval of < days after symptom onset. ili was defined according to the european union (eu) case definition as sudden onset of symptoms with at least one of the following four systemic symptoms: fever or feverishness, malaise, headache, myalgia; and at least one of the following three respiratory symptoms: cough, sore throat, shortness of breath. swabs were performed through usual surveillance. no ethical approval was needed, but an oral informed consent was requested. cases were excluded if they refused to participate in the study or if they were unable to give informed consent or to follow the interview in native language because of aphasia, reduced consciousness, or other reasons. an individual was considered as vaccinated against pandemic influenza if he or she reported having received a pandemic influenza vaccination during the current season, and if at least one vaccine dose occurred more than days before ili onset. the study period started with the initiation of active influenza surveillance by the grog network, i.e., days after the beginning of the influenza vaccination campaign, and finished at the end of the influenza period defined as the last week with at least one swab positive for influenza within the grog network. ''ad hoc'' sampling patients from which swabs were taken were selected by the grog practitioners during the study period. systematic random sampling during the same period, patients were selected at random as follows. an age-group - years (gps and pediatricians); - years (gps and pediatricians); - years (gps); years or more (gps) was assigned to each practitioner, who was requested to swab the first patient of the week presenting with an ili within the pre-assigned age-group. swabs were collected in appropriate transport medium (virocult Ò , viralpack Ò , utm copan Ò ) and sent by post to the laboratory in triple packaging following the international guidelines for the transport of infectious substances (category b, classification un ). laboratory confirmation of influenza was by rt-pcr to detect currently circulating influenza a (subtypes h , seasonal and pandemic h ) and b viruses. an influenza case was defined as an ili case with a respiratory sample positive for influenza during the study period. controls were cases of ili having a swab negative for influenza during the study period. the outcome of interest is laboratory confirmed influenza. confounding factors and effects modifiers identified during the i-move preliminary study were registered: risk factors, chronic diseases, severity of underlying conditions, smoking history, former vaccinations, and functional status. data on cases and controls were collected by the practitioners using a standardized questionnaire adapted from the i-move study. questionnaires were sent by the practitioners with the swab to the virology laboratory, and sent to the grog national coordination. data entry and validation were ensured by open rome through the vircases computing tool. validation steps included control of exhaustiveness of centralization of questionnaires, comparison of data entered by the labs and the national grog coordination, coherence control, and identification of missing data. analysis was done for the two sampling groups (systematic and ad hoc) on cases ⁄ controls following the european method proposed by epiconcept, using excel ª (microsoft corp. redmond, washington, usa) and stata ª . baseline characteristics of cases and controls in unmatched studies were compared using the chi-square test, fisher's exact test, or the mann-whitney test (depending on the nature of the variable and the sample size). the association between vaccination status and baseline characteristics was assessed for both case and control groups. the vaccine effectiveness was computed as ive = )or (odds ratio). an exact % confidence interval (ci) was computed around the point estimate. analysis was stratified according to age groups, time (month of onset), presence or absence of chronic disease, and previous influenza vaccination. effect modification was assessed comparing the or across the strata of the baseline characteristics. confounding factors were assessed by comparing crude and adjusted or for each baseline characteristic. a multivariable logistic regression analysis was conducted to control for negative and positive confounding factors using a complete case analysis (with records with missing data dropped) and using multiple imputation with chained equations. the complete model included age group, number of gp visits, onset week, seasonal vaccination, previous seasonal influenza vaccination, presence of chronic disease and associated hospitalizations in the previous months, gender, and smoking status. variables were tested for multi-colinearity. interactions were tested using the likelihood ratio test (or wald test) and included in the model if significant at % level. a model with fewer variables (age group, number of gp visit, onset week, and seasonal vaccination) was also tested. several models were applied to both the ''ad hoc'' and systematic sampling groups of cases and controls. as shown in table , whatever the analysis method used, the ''ad hoc'' sampling strategy led to a slightly lower estimate of ive. the ci were extended when data were missing and reduced when using multiple imputations with chained equations. however, from a statistical point of view, comparison of ''ad hoc'' versus systematic strategies is not straightforward, because ''ad hoc'' sampling is not randomized and does not allow comparisons with statistical tests using statistical distribution laws. there are more missing data with the ad hoc sampling method. this is mainly due to our validation procedure: in the case of missing data in the systematic sampling group, as required by the i-move study protocol, queries were sent to sentinel practitioners using mail and phone calls. this specific heavy workload is not usually performed during routine surveillance and has not been achieved for the ''ad hoc'' sampling group given the great number of cases and controls ( ). within the framework of the i-move study, several items were added to the grog's usual clinical form accompanying swabs (hospitalizations, number of gp visits, smoking status, help needed for bathing or walking). in - , gps explained that this added workload was not compatible with their daily additional workload due to the pandemic situation. therefore, many of them refused to fill these new items systematically and threatened to leave the network. we thus obtained that the ''i-move items'' would be filled in for the clinical forms linked to systematic sampling, but were not in a position to obtain that for ''ad hoc'' sampling. the weekly distribution of systematic swabbing is not similar to that of ad hoc swabbing. the percentage of ad hoc swabs was higher than systematic swabs during the pandemic wave (mid-november to end of december) during which time the percentage of swabs positive for influenza was also higher ( figure ). this could explain the higher rate of positive swabs within the ''ad hoc'' samples. the vaccination campaign was launched by the ministry of health on october , , and vaccination coverage increased during the surveillance period. in february, the vaccination coverage was ae % in patients swabbed in the systematic group ( ae % on imputed data) and ae % [ ae - ae ] in the ad hoc group ( ae % on imputed data). at the national level, vaccine coverage is estimated at ae %. due to the over-mediatisation of pandemic vaccination and to rumors about its poor effectiveness, overconsultation of vaccinated patients and over-swabbing of vaccinated patients in the ad hoc group are not surprising. age distribution is significantly different between our two samples (p < ae ): the rate of - years old is lower in the systematic sampling group ( ae %) than in the ad hoc sampling group ( ae %). this can be explained by the fact that for the systematic sampling procedure, each grog practitioner had to swab the first ili patient in his assigned age group, whereas for ''ad hoc'' sampling, every grog practitioner could swab any ili patient irrespective of age. given the emphasis by health authorities and media on the burden of pandemic influenza among children and teenagers, one can hypothesize that when they were able to, sentinel practitioners focused on these age groups. gps in the ad hoc sampling scheme seem to have been more likely to select cases and further, to select vaccinated cases. those patients may have consulted earlier with specific symptoms (strong headache being more prevalent among cases). over-swabbing of patients having these symptoms in the ad hoc group is likely. the - pandemic influenza season was markedly different from previous ones: vaccination rate increased during and mainly after the pandemic peak; behaviors were strongly modified by unusual media hype; clinical features and risk factors might be different. it will be necessary to see if similar results are observed during a regular influenza season during which the vaccination rate increases before the epidemic peak with usual messages about vaccination and usual clinical influenza features. influenza early warning networks can estimate ive, taking into account many covariates. from a stakeholders and patients point of view, during the - influenza pandemic wave, there were no major discrepancies between ive estimated with an ad hoc sampling strategy, based on sentinel practitioners instinct, and ive estimated with a systematic random sampling strategy whatever the multivariable analysis methodology. although from a statistical point of view, comparison of the two strategies is not readily feasible because of the non random nature of ad hoc sampling. this latter strategy seems to result in slightly lower ive estimates, which could potentially be attributed to sentinel practitioners swabbing behavior. the ability to avoid missing data is a key point to decide which sampling method must be adopted, because ci extent depends greatly on the proportion of missing data among covariates. to match ive evaluation to surveillance networks practicality, selection of only those data essential for the study endpoint and easily collected by sentinel practitioners is paramount. it will be necessary to determine if results similar to those observed during the - pandemic season are found during a regular influenza season. influenza a viruses are important pathogens which remain a major cause of morbidity and mortality worldwide, and large numbers of the human population are affected every year. the first influenza pandemic in this century broke out in humans in march , and it was declared to be pandemic by mid-june. as of august jul , the pandemic virus had caused more than deaths worldwide, according to the world health organization (http:// www.who.int/csr/don/ _ _ /en/index.html). the infection and spread of the pandemic influenza was reduced in part due to the use of vaccines. however, the lack of h n pdm vaccine early in the pandemic illustrates the need to improve vaccine production and to generate vaccines that induce stronger cross-protection. inactivated split vaccines or live attenuated influenza virus vaccines (laivs) against h n pdm viruses were approved for human use by the united states food and drug administration. both the inactivated vaccines and laivs are produced by creating reassortant viruses that generally contain six vrnas (pb , pb , pa, np, m, and ns) from a master donor strain, plus the two glycoprotein vrnas (ha and na) from a virus that antigenically matches the strain predicted to circulate in upcoming influenza season (e.g. a ⁄ ca ⁄ ⁄ ). the reference viruses containing inactivated split virus vaccines are produced in embryonated chicken eggs, and primarily result in the production of antibodies that recognize the viral glycoproteins. both of these vaccine approaches require significant lead time for vaccine production, and modern approaches to speed preparation of vaccines and improve their efficacy is a global priority. , the ns protein of influenza a virus is a multifunctional protein that plays important roles in virus replication and as potent type i ifn antagonist. , mutations and ⁄ or deletions in ns typically induce stronger ifn responses by the host; those in turn suppress the replication of influenza virus - and can enhance immune recognition. [ ] [ ] [ ] [ ] in this study, we created a panel of experimental h n pdm ns-laiv candidates that have different deletions in the ns vrna and analyzed the vaccine potential of each ns-laiv in mice and ferrets to identify the best candidate(s). wt h n pdm influenza a virus a ⁄ new york ⁄ ⁄ (ny ) was created by reverse-genetics directly from a human swab specimen collected in new york state in april . deletions were introduced into the ny ns plasmid to create three mutant ns segments: ns - , ns - , and nsd . nucleotides - (cdna of ns segment) and - were replaced by stop codons to generate ns - and ns - ; nucleotides - were deleted to generate nsd , whose open reading frames for ns and nep were maintained. recombinant viruses were generated by co-transfection of eight reverse-genetics plasmids carrying the cdna of each gene segment into t ⁄ mdck cocultured monolayer adapted from hoffmann et al. , mouse studies experiments were performed in a biosafety level laboratories approved by the u.s. centers for disease control and prevention and the u.s. department of agriculture, and were conducted under approved animal care and use protocols. groups of -week-old female balb ⁄ cj (jackson laboratory, bar harbor, me, usa) were anesthetized with isoflurane and inoculated intranasally with tcid of each recombinant virus in ll of pbs diluent, or pbs as controls. body weights and clinical symptoms of the mice were monitored daily for days. nine mice in each group were euthanized on , , and days post inoculation (dpi), and nasal washes and lungs were collected for virus titration by tcid assay in mdck cells. at dpi, mice per group were challenged intranasally with · tcid ( ld in -week-old mice) of a mouse-adapted variant of ny (a ⁄ ny ⁄ ⁄ -ma ) (accepted, journal of virology). disease symptoms and weights of the vaccinated mice were monitored for days, and four mice from each virus group were euthanized at and days post challenge. lungs were removed and homogenized for virus titration by tcid assay. the mice that became moribund or lost > % of their starting body weight were euthanized for humane reasons. male fitch ferrets (triple f farms, sayre, pa, usa), - months of age and serologically negative by hemagglutination inhibition (hi) assay for currently circulating influenza viruses were used in this study. groups of or ferrets were inoculated intranasally with ae tcid of one of the viruses: ny wt (n = ), ns - (n = ), ns - (n = ), or nsd (n = ). ferrets were monitored for clinical signs through dpi as previously described. nasal washes were collected on , , , and dpi and were titrated in mdck cells by tcid assay. serum was isolated from blood collected ae weeks after immunization and used for neutralization assays. the ferrets were challenged with pfu of a ⁄ mexico ⁄ ⁄ ae weeks postimmunization and monitored for clinical signs of disease through dpi. nasal washes were collected on , , , and dpi, and were titrated in mdck cells by plaque assay. using reverse genetics, we created three laiv candidates weight loss of wt virus inoculated mice became evident at dpi, and the mice did not recover until dpi (figure a) . in contrast, mice inoculated with any one of the vaccine candidates had no clinical signs of disease and continued to gain weight at the same rate as did the mock- inoculated mice ( figure a ). viral titers in the lungs of ns - , and ns - infected mice were $ -fold lower than titers from wt virus-infected mice at all the time points analyzed ( , , and dpi) ( figure b) . notably, the nsd laiv was cleared from the mouse lungs very rapidly, and the mean titers were $ -fold and -fold lower than the titers of the wt virus at and dpi, respectively ( figure b) . the vaccinated mice were challenged with a mouseadapted variant of ny (accepted, journal of virology) on dpi. no disease symptoms were observed in the mice immunized by any of the ns-laiv candidates or the wt control. in contrast, disease symptoms including ruffled fur, hunched posture, and weight loss were observed in the mock-immunized mice as early as days post challenge (dpc); the symptoms progressed to severe disease, and the animals showed dramatic weight loss, became moribund, and succumbed to infection by dpc (figure c ). high titers of virus ($ tcid ⁄ ml) were present in the mock-immunized mice at dpc and at dpc ( figure d ). in contrast, virus was not detected in the lungs of immunized mice ( figure d ). this challenge data demonstrates that all of the ns-laiv candidates, including the highly attenuated nsd , induced sterilizing immunity that protected mice from a lethal ny h n pdm variant. groups of ferrets were intranasally immunized with ae tcid of each vaccine candidate or the wt virus. the titer of viruses recovered from nasal washes ranged from ae to ae tcid ⁄ ml through day in the wt virusinfected group, while the ns-laivs showed various degrees of attenuation (figure a) . the viral titer of all of the ns-laivs is at least -fold lower than that of wt in the nasal wash collected at dpi. the ns - laiv was the least attenuated in ferrets, and its replication was similar to that observed in mice. relative to the wt virus, the ns - laiv showed -fold reduction in titer, and the nsd laiv was below the limit of detection (at least fold reduction) at dpi. sera from blood collected ae weeks after immunization was analyzed for the presence of neutralizing antibodies by micro-neutralization assays. the ns-laiv candidates all induced very strong neutralizing antibody responses ( - ) that were similar to the titer elicited by wt virus infection ( figure b ). the ferrets were challenged with pfu of a ⁄ mexico ⁄ ⁄ (h n pdm) ae weeks post immunization. little disease or weight loss were observed in the naïve ferrets, and the ferrets immunized by infection with wt virus or the ns-laiv candidates didn't show any disease symptoms or weight loss. in contrast to the high titer of virus detected in the naïve ferrets through dpc, the ns-laiv immunized ferrets had very low levels of a ⁄ mexico ⁄ ⁄ in their nasal washes at dpc ( figure c ). the ferrets immunized with the ny ns-laivs had $ -to -fold lower viral titers than did the naïve animals ( figure d ). in summary, the ns-laiv candidates dramatically inhibited initial replication of the h n pdm virus under stringent challenge conditions ( pfu), and that the vaccinated animals rapidly cleared the infection (to below the limit of detection, by dpc). our results demonstrate that all of the ns-laiv candidates are attenuated compared to the wt h n pdm virus, and the degree of attenuation is dependent on the specific ns mutation. ns - was the least attenuated and does not represent a good vaccine candidate; whereas, nsd and ns - were highly attenuated in both the mouse and ferret models. although they were markedly attenuated, they elicited strong neutralizing antibody responses and protected mice and ferrets from subsequent challenge. nsd has a subtle in-frame deletion ( nt) that affects both the ns (residues - ) and nep (residues - ), and is analogous to a naturally attenuated variant of a normally highly pathogenic h n virus (a ⁄ sw ⁄ fj ⁄ ). the analogous ns deletion in a ⁄ sw ⁄ fj ⁄ (residues - ) was shown to reduce binding to host cleavage and polyadenylation specificity factor (cpsf), reduce ns protein stability, and enhance the type i ifn response of this h n virus. our study indicates that deletion of these nt in the ns vrna of the h n pdm also stimulates the host ifn response, specifically, ifn-ß, ifn-k , ip , and mxa (data not shown). the role of the deletion of residues - from nep has not been elucidated, but the induction of ifn and isgs by nsd was similar to, or slightly lower than, their induction by ns- , suggesting that the nep mutation also has an attenuating effect that warrants future investigation. in summary, we have generated a panel of laivs directly from a swab specimen containing a new pandemic virus and analyzed their attenuation and immunogenicity in two animal models. our study demonstrates that nsd is a novel ns-laiv that could be used to create laivs for diverse influenza a viruses. this study also validates the use of ns-laiv candidates, which are not only highly attenuated, but they also elicit strong innate and adaptive immune responses, resulting in protection of mice from subsequent challenge with a lethal mouse-adapted variant of ny , and ferrets from challenge with a ⁄ mexico ⁄ ⁄ (h n pdm). currently, a total of approximately million doses of inactivated influenza vaccine are being produced worldwide each year. one of the limitations in vaccine production is poor growth of human isolates in embryonated chicken eggs. this is essential to develop high yield seed viruses for large scale production of influenza vaccines. influenza a vaccine production utilizes high yield reassortants carrying ha and na genes from a wild type (wt) strain with generally - internal genes from the a ⁄ pr ⁄ ⁄ (pr ) strain, an highly egg adapted high growth donor strain. influenza b vaccines, however, have been produced directly from wt strains, partly because no high yield donor analogous to pr has been identified. in recent years, reverse genetics has been used as an alternative means of developing high growth vaccine viruses. , since in this plasmid-based technology, a : reassortant (six internal genes from a donor strain and two surface antigen genes from wild type strain) can be directly rescued, reverse genetics-derived reassortant viruses were expected to grow as efficiently as those derived from classical reassortment. however, reverse genetics reassortants have not produced the expected high growth for several reasons: (i) the : configuration is not always the best for virus yield, (ii) there is no process included for positive selection of adaptive mutants from quasispecies, and (iii) cell-derived viruses are not readily adapted to grow efficiently in eggs. our laboratory at new york medical college has been preparing b reassortants for several years by classical reassortment using b ⁄ lee ⁄ as a donor. it has been possible to develop b reassortants, which produce higher virus yields than wt strains in eggs, and it was found that the np gene of b ⁄ lee ⁄ was important in producing high yield b reassortants. however, b ⁄ lee ⁄ is inconsistent in providing high yield properties to b reassortants. in this study, in an attempt to find an alternative donor, we investigated the usefulness of b ⁄ panama ⁄ ⁄ for developing high yield b reassortants. as a wt strain, b ⁄ brisbane ⁄ ⁄ was used, which is one of the recommended influenza b virus vaccine strains for the ⁄ and ⁄ seasons. we found that b ⁄ panama ⁄ ⁄ is a useful donor, and some of the resultant reassortants were considered as vaccine candidates. b reassortant viruses were prepared by the classical reassortment method described by kilbourne. the antiserum to b ⁄ panama ⁄ ⁄ hemagglutinin and neuraminidase (hana) was raised in this study by immunizing rabbits with hana isolated from b ⁄ panama ⁄ ⁄ ; purified igg was used for antibody selection. the yields of the reassortants and their corresponding parent viruses were assessed by hemagglutination assay. viral rna was extracted directly from the allantoic fluid and amplified by rt-pcr to produce cdna for analyzing the gene composition. restriction fragment length polymorphism (rflp) analyses were performed to determine the origin of each gene segment of the high yield reassortants. restriction enzyme sets for each gene segment are available upon request. in this study we investigated the usefulness of b ⁄ panama ⁄ ⁄ as a donor for transferring high yield phenotype. b ⁄ panama ⁄ is a yamagata lineage strain with high growth phenotype (ha titer: - ). b ⁄ panama ⁄ ⁄ itself was a recommended b virus vaccine strain for ⁄ - ⁄ seasons. as a wt virus, a victoria lineage strain, b ⁄ brisbane ⁄ ⁄ , was used, which is a recommended b virus vaccine strain for use in the ⁄ and ⁄ seasons. reassortants were prepared according to classical reassortment protocol. after co-infection of b ⁄ panama ⁄ ⁄ and b ⁄ brisbane ⁄ ⁄ , progeny viruses carrying surface antigens (ha and na) of the vaccine strain were negatively selected by anti-b ⁄ panama hana antibodies, followed by passages without antibodies for positive selection of eggadapted viruses and finally limited dilution cloning. nymc bx- , bx- b, bx- d, and r- a are representative of resultant reassortants, which have significantly higher ha titers than the wt strain. the complete gene compositions of these reassortants were determined by rt-pcr ⁄ rflp analyses. as shown in table , all of these reassortants contained the pb of b ⁄ panama ⁄ ⁄ . other genes of b ⁄ panama ⁄ ⁄ (np of bx- , m of bx- b, and pb of bx- d) may not be involved in the high virus yield, since no significant growth difference among these reassortants in eggs was found as assayed by hemagglutination test. accordingly, the pb of b ⁄ panama ⁄ ⁄ is considered to be the sole factor involved in the high yield phenotype donated to the vaccine strain. we previously found that the b ⁄ lee ⁄ np gene was important in producing high yield b reassortants. it was of interest to examine whether b ⁄ lee ⁄ np and b ⁄ panama pb could work together to produce even higher yields. to test this possibility, bx- b ( : reassortant: pb and m genes from b ⁄ panama and the rest of the genes from b ⁄ brisbane) was selected and further reassorted with b ⁄ lee ⁄ . despite some difficulty in removing the na gene of b ⁄ lee ⁄ (r- c, b, b in table ), by monitoring ha and na genes of resultant viruses after each antibody selection passage with anti b ⁄ lee ⁄ hana antibodies, we were able to isolate and clone a triple reassortant, nymc bx- , which contains the np gene from b ⁄ lee ⁄ and pb and m genes from b ⁄ panama; the remaining genes are from b ⁄ brisbane ⁄ ⁄ (table ). in comparison with bx- b, no significant growth enhancement (nor reduction) in eggs was found for bx- over that seen for bx- b. nevertheless, bx- stably produces high virus yield and has been utilized as a seed virus for influenza b vaccine production for the - season by one or more vaccine manufacturers. there are contradictory reports - about the usefulness of reassortment for high yield influenza b viruses. however, we have been preparing b reassortants for several years by classical reassortment using b ⁄ lee ⁄ as a donor, and have been able to generate higher virus yield than wt strains. in this study, we found that b ⁄ panama ⁄ ⁄ serves as an efficient donor in providing the high growth capacity to b ⁄ brisbane ⁄ ⁄ (a recommended vaccine virus of victoria lineage for ⁄ - ⁄ seasons), and that the pb of b ⁄ panama ⁄ ⁄ is associated with the high yield phenotype. this particular strain from yamagata lineage might be useful to prepare high yield reassortants for other victoria lineage vaccine viruses. we noticed in this study that there may be segment incompatibilities between b ⁄ panama ⁄ ⁄ and b ⁄ brisbane ⁄ ⁄ . as shown in table , the pa and ns genes of all the high yield reassortants examined are derived from wt, b ⁄ brisbane ⁄ ⁄ , not from the donor, b ⁄ panama ⁄ ⁄ . this indicates that in this reassortment, the pa and ns genes are not replaceable with that of the donor to obtain high yield viruses. this degree of incompatibility might be common in b reassortment, resulting in low donor ⁄ wt reassortants, such as : and even : reassortants that we obtained in this study. if this is the case, reverse genetics based on : configuration may not result in generating high yield b reassortants unless a variety of donor ⁄ wt combinations are designed. one can speculate that in influenza b viruses, the surface glycoproteins (ha and na) and some of the internal proteins are functionally more closely related than in influenza a virus, as was seen in that pa and ns genes of b ⁄ brisbane ⁄ ⁄ reassort together with the ha and na genes of the same parent (table ). in our recent study on a reassortment between b ⁄ lee ⁄ and b ⁄ panama ⁄ ⁄ , it appeared that ha shapes overall gene constellations of the resultant reassortants, namely the reassortants tend to have more internal genes from the same parent of ha, no matter which parent's ha is selected by antibodies against the surface antigens of the other parent (data not shown). because of success in influenza a virus reassortment with pr , it is generally believed that reassortant with : or : configuration is optimal for virus yield. this may be the case in most instances of influenza a reassortment, but is not necessarily so in b reassortment. as shown in this study, only a single donor gene is capable of improving the yield of vaccine strain by reassortment. influenza a ⁄ h n v has spread rapidly in all parts of the world in as a true pandemic. epidemic events in russia occurred during the last week of september starting from far east region (yuzhno-sakhalinsk). kaliningrad (the western most russian city) was the second starting point of the epidemic. during october the epidemic spread over the whole russian territory. in a short period the new virus started to change genetically as it began to adapt to human populations during this pandemic (http://www.who.int; http://www.euroflu.org). in the period from may to december , clinical samples (nasopharyngeal swabs and postmortem materials) of patients with influenza-like illness from different regions of russian federation were analyzed to confirm the diagnosis using real-time reverse transcription pcr (rrt-pcr). clinical nasopharyngeal swabs and bronchoalveolar lavage and post mortal fragments of trachea, lungs, bronchi, spleen from saint petersburg hospitals and basic laboratories of federal influenza center were included in this study. all specimens were taken from patients with influenza-like illness or viral pneumonia. specimens were tested by rrt-pcr according to cdc protocols, i.e. using superscript iii platinum one-step qrt-pcr system (invitrogen) with primers and probes for infa, h seasonal, and h sw (biosearch technologies). in addition, the test-systems 'amplisense influenza virus a ⁄ b-fl' and 'influenza virus a ⁄ h -swine-fl' for pcr-detection, typing and subtyping of influenza viruses were also used. these test-systems are produced by central institute of epidemiology, moscow, russia and recommended by russian ministry of health as tests for influenza diagnosis. sequencing was carried out on an abi prism -avant genetic analyzer (applied biosystems, usa) with bigdye terminator cycle sequencing kit. phylogenetic analysis was performed using programs vector nti . (invitrogen) and mega . (psu, usa) by maximum likelihood with the tim+i+g model for ha, and -hky+i+g model for na. evolutionary model was selected by akaike information criterion (aic) in model-test (posada, crandall, ). statistical reliability of tree branches was evaluated by bootstrap test ( replications). immunohistochemical study was performed using novalink antibodies to ha and np with novocastra visualization system. influenza virus a ⁄ h n v rna was detected in patients with severe form of influenza-like illness and fatal cases. out of pcr-confirmed flu recovered cases % were patients under years of age, % were aged - years, and % were older than years. mean age of recovered patients was ae years (from month to years). viral rna in postmortem materials was detected mostly in lung tissue ( % of specimens) and trachea fragments ( %), and less commonly in spleen ( %). mean age of the deceased with confirmed flu (h n v) infection was ae years with age ranging from months to years. in % of fatal cases, influenza was complicated by viral or secondary bacterial pneumonia. median time from the onset of illness until death was days. according to our data, % of patients died had diabetes, ae % were obese, and % were pregnant women in the nd or rd trimester. ha and np were detected by immunohistochemical assay in lung tissue of dead patients with confirmed influenza virus a ⁄ h n v infection. ha and np was revealed in the endothelium of different sized blood vessels (capillaries and arterioles). these influenza virus proteins were also detected in some tissue macrophages apart from epithelium and endothelium. the localization of the two proteins was different: ha is mostly localized in cell membrane and cytoplasm, and np -mostly in the nucleus. here we present data on molecular genetic characteristics of strains of pandemic virus, strains obtained from clinical specimens, and from post mortal ones isolated in the research institute of influenza. all the strains studied contain the s n substitution in m protein, which indicates resistance to the adamantane antivirals, and have no h y substitution in the neuraminidase, which indicates resistance to oseltamivir. the phylogenetic analysis showed that russian viruses were similar to influenza viruses a ⁄ texas ⁄ ⁄ and a ⁄ california ⁄ ⁄ (ha similarity ae %). all russian viruses could be divided in two clusters: the first one includes viruses similar to the reference strain a ⁄ california ⁄ ⁄ , and the second one, which is the majority of viruses analyzed includes strains with substitutions ha s t, na n d, v i, and ns i v (figure ). bootstrap support was . the isolates with ha s t substitution can be classified in one of the five minor genome variants of a ⁄ h n v viruses found in the united states and mexico in . several viruses had strain-specific substitutions in antigenic sites sb and ca and the mutation d g in ha receptor-binding site. the substitution of amino acid residue asp to gly at position of ha was found in eight of eleven isolates ( %) from postmortem lung and trachea samples and two of forty isolates ( %) from nasopharyngeal swabs of patients with severe course of the disease. appearance of amino acid substitutions in the ha receptor-binding site (d e and d g ⁄ e) could be associated with influenza virus passaging on eggs. five strains that contained g at position of ha were isolated from post mortal specimens on mdck cells in this study, thereby excluding the possibility of substitution appearance hence to virus adaptation on eggs. in order to reveal genome changes in a(h n )v, strains isolated on the territory of russian federation during the pandemic, full genome sequences from genbank, and research institute of influenza database were analyzed comparing two groups of viruses (isolated before and after sept ). nine amino acid changes observed predominantly in late pandemic strains were found. five of them (s p, s n, d g, v i, v i) reside in ha, two in na (i v, n k), two in pb (k n, t i), and one in pa (f l). towards the end of the epidemic the viral population had demonstrated statistically certain rise in number of strains containing mutations in four genes. difference between groups was statistically significant (chisquare test, p = ae ). if v > ae , than difference between early and late strains is statistically significant. additionally fisher's test determined whether 'early strains' and 'late strains' differ significantly in the proportion of 'no mutation event' and 'mutation event' attributed to them in each particular position. all calculations were performed in fisher_tk freeware by vladimir belyaev similar to calcfisher (haseeb, ) fully described here (http://www.jstatsoft.org/v /i /paper). we have selected positions with statistically significant amino acid changes in late strains (p-value ae ). according to full genome analysis of influenza virus a ⁄ h n v strains, seven clades were distinguished, but the divergence between representatives of different clades remained small. (figure ). besides the strain a ⁄ perth ⁄ ⁄ also contains substitution s f in the same ha antigenic site. according to data obtained, the epidemic in russia was caused only by influenza virus a ⁄ h n v. unlike the previous epidemic periods when most severe influenza cases were registered among the children under years and among elderly people aged over years, the first wave of pandemic due to influenza virus a (h n )v resulted in increased level of mortality mainly among the people aged - years. though all pandemic viruses showed comparative genetic homogeneity, some evolutionary trends could be outlined. for clarification of the exact pathogenic role of mutation d g in ha receptor binding site, further studies are necessary. full-genome analysis of influenza virus a ⁄ h n v strains circulating in the southern hemisphere in the new epidemic season revealed the phylogenetic subgroup distinguished by seven substitutions in inner proteins (pb , pb , np, ns ) and sa antigenic site of ha (n d). the changes revealed could be caused by adaptation of the virus to an immunized human population. nasal and throat swabs (placed in ml mem and frozen at ) °c until use for viral rna extraction and tissue culture inoculation) were collected from patients with febrile illness, i.e., > ae °c. samples were received from clinics in us embassies and us military laboratories located throughout the world since the initial who declaration of novel h n outbreaks as a global pandemic on june , . viral isolates were obtained from inoculating cultures of mdck cells with ae - ae ml viral suspensions collected in mem originated from patients after - days incubation. [ ] [ ] [ ] [ ] due to low viral titers in normal clinical samples, most of full viral genome sequences were derived from viral stocks obtained by tissue culturing passages (mdck, - times). viral rna was extracted from clarified supernatant fluid of nasal ⁄ throat swabs or mdck cultures using the 'charge-switch' rna extraction system based on the user manual protocol from the manufacturer (invitrogen inc., ca, usa). total rna was eluted into volume equal to original sample volume, i.e., ll starting viral supernatant used to yield final ll rna in molecular grade water (invotrogen inc.) and stored at ) °c until tested. generating ⁄ preparing overlapped cdnas for full genome coverage of novel h n viruses by multiple rt-pcr amplifications the first step in the high-throughput sequencing pipeline for full influenza genome sequences was to establish a robust rt-pcr amplification scheme consisting different rt-pcr primer pairs covering all rna segments to ensure % amplification coverage of full viral genomes of all the incoming targeted viruses (houng, hs. , submitted for publication). extracted viral rna ( ll), derived from mostly mdck culturing stock or clinical sample containing sufficient viral load (> infectious units per ml) was added to primer-free rt-pcr total master mixture ( ae ll) for each virus followed by adding primer pair ( ll, pmole ⁄ ll per primer). rt-pcr was then performed: rt reaction through two hold-steps ( °c, minutes and °c, minutes); cycling amplifications ( °c for seconds, °c for seconds, °c for ae minutes). specific cdna amplicons corresponding to each individual primer pair were routinely monitored and visualized by agarose gel electrophoresis. pooled cdna products ( - lg) from each viral rt-pcr amplification run were used as sequencing substrates according to the roche flx user manual and bulletins by incorporating adaptors containing individually multiplex identifier [mid]-key assigned to each individually pooled viral cdna. up to different mid-keyed viral cdna were further pooled together to be clonally amplified on capture beads in water-in-oil emulsion micro-reactors (em amplifications), and pyrosequenced using one of two regions of a · mm picotiterplate. for each individual viral genome containing multiple assemblies ( rna segments), we obtained sff file(s) containing raw sequencing reads from which nucleotide sequence data and phredlike quality scores were extracted. on average, ae - ae % of - million mid-key specific nucleotides were extracted and mapped for consensus genome sequences. roche gsmapper (v. . and . ) software was used to assemble all sequencing raw data and sff files into consensus sequences. new reference mapping projects were created to assemble each individually mid-keyed viral cdna into consensus viral sequences. one of the earliest h n genomes of california origin, a ⁄ california ⁄ ⁄ (h n ), deposited in genbank, was routinely employed as a reference genome sequence for most of gsmapper projects. the resultant consensus sequences obtained were further verified and validated through the ncbi annotation utility check and ultimately deposited to the ncbi influenza database, genbank. nucleotide sequences specific to each individual rna gene were aligned by the geneious pro . . software (http://www.geneious.com). trees were built based on the tamura-nei genetic distance model using the neighbor-joining method with no outgroup used via geneious pro . . . phylogenetic trees of the h n genomes were constructed by importing fasta files containing specific concatenated target sequences of pb , pb , pa, ha, np, na, mp, and ns from each individual virus into the geneous pro software and going through the sequence assembling and tree building steps. high-throughput pyrosequencing of pooled novel h n cdnas by roche flx system up to viral cdnas could be routinely sequenced to completion for different full viral genomes from a single roche flx picotiter plate by utilizing the combination of pico-titer plate's two distinct regions as well as different mid-keyed adaptors. the 'shotgun' sequencing approach employed in this study is a feasible method to viral isolates (n) sequence multiple pooled h n viral genomes. for each pyrosequencing experiment, approximately - passed key reads (single fragment per bead) were obtained that yielded readable nucleic acid sequences. among those close to a million passed key reads, only - passed key reads had an average sequencing read length of > bps, defined as 'long reads' ( bps · reads = total of million bases of nucleic acid sequences) that were used to assemble into influenza genome sequences. mathematically, - million bases of raw sequencing data from each single roche flx experiment would provide sufficient sequencing bases to cover full genome sequences with approximate - · of sequencing depth coverage of influenza a with average genome size of bps for the total of eight segmented rnas. so far, more than full h n genomes sampled worldwide have been successfully sequenced and deposited in the ncbi database by division of viral diseases, walter reed army institute of research (wrair). the bioinformatics derived from unique viral genome sequences generated from this study based on constant rt-pcr amplification scheme and identical roche pyrosequencing protocols provide a reliable data set in predicting the evolutionary patterns of pandemic viruses. wrair received clinical samples from us embassies and military personnel throughout the world since the initial who announcement of novel h n outbreaks. nearly equal distributions of sequenced viruses derived from three broadly categorized geographic regions, north america, central ⁄ south america, and asia ⁄ europe ⁄ africa (data not shown). besides the geographic distribution pattern of viral isolates, figure displays the viral isolation time lines of all the sequenced viruses reflecting two peaks that coincided with two waves of pandemic infections, early-mid summer and fall of . phylogenetic trees of the eight influenza a segments of all sequenced viruses were tentatively generated. it was found that the substitution frequencies per site for the ha, na, and ns genes are at much higher rate than the other five genes, pb , pb , pa, np, and mp genes (data not shown). the observed higher genetic variations for ha and na genes of h n are consistent with the historical genomic and epidemiological dynamics data of human influenza a revealing higher temporal fluctuations in ha and na genes. [ ] [ ] [ ] [ ] analysis of full influenza genomes containing concatenated eight complete rna segments revealed the existence of two distinctive genetic clades in circulation since the beginning of pandemic, as shown in fig-ure . it is noteworthy that all viruses of mexico and california origins (clade shown at the top of figure ) were isolated at the beginning of pandemic prior to the isolation of all other viruses belonging to the second genetic clade . , discussion during the past decade, the advance of dna sequencing technology, such as development of ngs, in making full viral genome sequences readily available have enabled study of far broader and more detailed aspects of evolutionary change for any new emergent infectious pathogen. the massive sequencing capacity of roche flx system allows simultaneously process and sequence millions of individual cdna molecules, in contrast to processing and sequencing individual cdna fragments by conventional sanger sequencing method. within a short period of few months since the beginning of the pandemics, wrair accomplished large number of representative h n full genomes of worldwide origins via roche flx system. sequencing data derived from this study illustrates a much higher genetic variation rate for ha and na genes of h n that is compatible to the higher temporal fluctuation rate for ha and na genes of seasonal influenza a derived from decades of intensive monitoring and comparison studies and analyses. [ ] [ ] [ ] [ ] following the mexican and us reported cases, confirmed outbreaks of swine h n rapidly proliferated and spread throughout europe, asia, africa, and south america, most probably via global airline travel. , it seemed that new cases in the us and most cases throughout the world had been clinically mild relative to the initial reported cases in mexico. [ ] [ ] [ ] [ ] here we demonstrate through the phylogenetic relationship of sequenced h n full genomes that the clinical isolates could be divided into two different clades of viruses, i.e., the clade genetic group contains only viruses isolated at the beginning (march ⁄ april , mexico and california) of pandemics and the rest of other viruses all belong to the nd genetic group, clade . thus, it's likely that the currently circulating h n of clade causing worldwide infections is genetically different from the initial h n isolates that caused the early infections in mexico and california. , introduction a pandemic influenza virus ( h n ) was recently introduced into the human population. the hemagglutinin (ha) gene of h n is derived from 'classical swine h n ' virus, which likely shares a common progenitor strain with the human h n virus that caused the pandemic in . since antigenic changes of influenza virus ha occur more slowly in swine than in humans, we hypothesized that h n might still retain an antigenic structure similar to that of h n or the early isolates of its descendants. in this study, we compared ha antigenic structures of h n and human h n viruses by a molecular modeling approach to demonstrate the existence of shared epi-topes for neutralizing antibodies. we found that has of h n and the h n virus shared a significant number of amino acid residues in known antigenic regions. from this observation, we hypothesize that the h n ha antigenic sites will be targeted by antibody-mediated selection pressure in humans in the near future. we further discuss possible directions of antigenic changes in the evolutionary process of h n . sequence data of ha genes modeller v was used for homology modeling of ha structures. after models of the ha trimer were generated, the model was chosen by a combination of the mod-eller objective function value and the discrete optimized protein energy statistical potential score. after addition of hydrogen atoms, the model was refined by energy minimization with the minimization protocols in the accelrys discovery studio . software package using a charmm force field. steepest descent followed by conjugate gradient minimizations was carried out until the root mean square gradient was less than or equal to ae kcal ⁄ mol ⁄ a. the generalized born implicit solvent model was used to model the effects of solvation. the ha model was finally evaluated by using procheck, whatcheck, and verify- d. custom-made programs were developed with the ruby language and used for investigating the numbers of potential n-glycosylation sites and candidate codons (cand ) in ha sequences. it is known that the h ha molecules have four distinct antigenic sites: sa, sb, ca, and cb. , as a result, these sites consist of the most variable amino acids in the ha molecule of the seasonal human h n viruses that have been subjected to antibody-mediated immune pressure since its emergence in , although it was absent in humans from to . to investigate the structures of these antigenic sites of h n , d structures of the ha molecules of sc , the recent seasonal human h n virus (br ), and h n (ca ) were constructed by a homology modeling approach, and compared by mapping all the amino acid residues that were distinct from those of sc ha (data not shown). we found that most of these antigenic sites of br ha predominantly contained altered amino acid residues if compared with sc . by contrast, amino acid residues at these positions were relatively conserved in ca ha when compared with sc ha. notably, the sa and sb sites, which contain many amino acids involved in neutralizing epitopes near the receptor binding pockets, remain almost intact ( table ), suggesting that antibodies raised by natural infection with sc or its antigenically related descendant viruses play a role in specific immunity against ca . these observations lead us to hypothesize that such antigenic sites involving the conserved amino acids will soon be targeted by antibody-mediated selection pressure in the human population. based on this hypothesis, we speculated that h n would undergo patterns of amino acid substitutions in ha similar to those seen in seasonal human h n viruses during its epidemic period (i.e. those that have been substituted since ) (figure ) . we then predicted possible amino acid substitutions of h n from the sequence similarity of the antigenic sites. for example, both sc and ca had an asn residue at position in the sa site. for sc , the residue at this position has altered from asn to lys since . combining these two facts, it seems reasonable to hypothesize that ca will also undergo an amino acid substitution from asn to lys at position in the future. interestingly, we found that some of the recent variants of the h n virus have indeed undergone substitutions identical to those predicted in figure . it is important to monitor whether such variants will be selected and survive in sustained circulation in humans. next, we analyzed the acquisition of potential n-glycosylation sites associated with antigenic changes. previously, we reported that cand sites, a set of three codons that require single nucleotide substitution to produce n-glycosylation sequons, were important motifs to rapidly acquire n-glycosylation sequons. therefore, we investigated the number and location of potential n-glycosylation sites and cand sites in h n ha. we found that ca also had a single n-glycosylation sequon at the same position in the globular head region of ha, and lacked the multiple n-glycosylations that have been observed in the antigenic changes of the human h n virus during the early epidemic of this virus. we also found that ca ha possessed three cand sites that were present at the same position in sc ha (positions of the first asn residue, , , and ). of these, the cand sites with positions at and had actually become potential n-glycosylation sites in human h n viruses. this result suggests the likelihood of additional n-glycosylation at these sites during future antigenic changes of h n ha. notably, some of the recent h n variants (as of march , ) have an additional n-glycosylation sequon at position , where the h n virus readily acquired an n-glycosylation site during its circulation. the present study suggests that the antigenic structure of h n ha is similar, at least in part, to that of the h n ha. the and h n has share unique three-codon motifs that are important to readily acquire n-glycosylation sequons in their globular head region. based on these similarities, we predicted possible amino acid substitutions that might be associated with future antigenic changes of h n , and confirmed that such substitutions occurred in some of the recent variants of this virus. the present study provides an insight into likely future antigenic changes in the evolutionary process of h n in the human population. influenza viruses are classified into three types, a, b, and c, based upon the antigenic properties of nucleoproteins and matrix proteins. influenza a virus infects a wide range of hosts, including human, bird, swine, equine, and marine mammal species, while influenza b and c are less pathogenic than influenza a and are mainly found in humans, although there is evidence that they can also infect other species. influenza a has evolved in association with its various hosts on different continents for extended periods of time. to survive as a successful pathogen, the influenza viruses have developed a number of mechanisms, including antigenic mutation and genome reassortment, to continuously evolve and evade the surveillance of the host immune systems. antigenic and genetic analyses have provided important insights into the molecular dynamics of influenza virus evolution. however, a comprehensive understanding of influenza viral genetic divergence and diversity remains lacking. neuraminidase (na) is a major surface glycoprotein of influenza a and b, but is absent in influenza c. it plays a key role in virus replication through removing sialic acids from the surface of the host cell and releasing newly formed virions. influenza a viral na genes are classified into nine subtypes (na -na ) based upon their antigenic properties, while na genes of influenza b are not classified into subtypes. furthermore, most na subtypes of influenza a have evolved into distinct lineages and sub-lineages, which correspond to specific hosts or geographical locations. in this study, we conducted large-scale analyses of influenza na sequences in order to infer their evolution and to identify lineages (or sub-lineages) of influenza a viruses. a total of na sequences that excluded laboratory recombinant sequences were downloaded from genbank. sequences were aligned with muscle and mafft. the alignments were adjusted manually using translatorx, based upon corresponding protein sequences. phylogenetic analyses were conducted using the maximum-likelihood (ml) method in raxml. a set of perl scripts were written by us to facilitate this computational analysis. lineages and sub-lineages were determined based on the topology of the ml trees. additional information such as hosts, geographical regions, and circulation years were also considered in the classification. we used the same lineage nomenclature as described in, but with the following modifications: a single digit is used to represent one of the nine subtypes and a letter is used to represent a lineage; a sub-lineage is also represented using a digit; a dot is used to separate a lineage and a sublineage. for example, a. means na subtype, lineage a, and sub-lineage . the time of most recent common ancestor (tmrca) was estimated using the bayesian mcmc method in beast. in all cases, we employed the gtr + u nucleotide substitution model, in which the first and second codon positions are allowed different rates relative to the third codon position. all data sets were analyzed under a relaxed molecular clock and the bayesian skyline population coalescent prior. the maximum clade credibility (mcc) tree across all plausible trees was computed from the beast trees using the treeannotator program, with the first % trees removed as burn-in. phylogenetic analysis based upon na sequences revealed two large groups corresponding to influenza a and b, respectively ( figure a ). within influenza a, two subgroups were found, one consisting of na , na , na , and na and the other consisting of the remaining five subtypes. subtype na was found to be a sister subtype of na , na being a sister subtype of na , and na a sister subtype of na . finally, each na subtype forms a distinct cluster, indicating its genetic uniqueness. influenza a and b viral na were estimated to have diverged around years ago ( figure b ). however, it had large % hpd values which ranged from years to years ago. the na subtypes of influenza a diverged from more than to several hundred years ago. the time of most recent common ancestor (tmrca) of each subtype of influenza a virus was generally recent and ranged from the calendar years to (figure b ). in addition, the tmrca for influenza b viral na was dated back to . a total of lineages were identified in influenza a (table ) . three lineages, a, b, and c, were identified for na based upon the tree topology. linage a originated from avian viruses and was further divided into sub-lineages: a. , a. , a. , a. , and a. . linage b consists of north american swine influenza viruses whereas c is a human lineage. two large lineages, a and b, were identified in na . lineage a is a human-specific lineage. interestingly, five major swine clades were observed within this lineage. lineage b is an avian-specific lineage, and consists of sub-lineages, b. , b. , and b. . three lineages were found in na . lineage a was found in north american avian, b in eurasian ⁄ oceanian avian, and c also in avian, but it does not show any geographical pattern. for na , na , and na , each was classified into lineages, one found in north american avian ( a, a, a) and the other in eurasian ⁄ oceanian avian ( b, b, b). three lineages identified respectively in na and na are north american avian ( a, a), equine ( b, b), and eurasian avian ( c, c). na was also found to have lineages: north american avian ( a), eurasian ⁄ oceanian avian i ( b), and eurassian ⁄ oceanian avian ii ( c), respectively. in this study, we conducted large-scale phylogeny and evolutionary analyses using influenza viral na sequences. the results showed that divergence between influenza a and b viruses occurred earlier than between any influenza a subtypes. this observation was consistent with previous findings based upon phylogenetic analysis of the ha gene, one of the most important genes related to host infection. within influenza a, two sub-groups were found, one consisting of na , , , and and the other consisting of the rest of five subtypes (na , , , , ) . this observation does not agree with the result described by liu et al., where na subtypes , , , , and formed one group and the remaining four subtypes (na , , , and ) formed the other group. this difference is apparently caused by the fact that an outgroup was not used in their phylogenetic analyses. in the present study, both influenza a and b viral na sequences were included in the analysis. high bootstrap values were obtained for major groups, indicating that the inferred evolutionary relationship should be highly reliable. classification and designation of the lineages and sublineages within the influenza a virus are essential for studies of viral evolution, ecology, and epidemiology. a total of lineages were identified within nine influenza a viral na subtypes and with the majority of the identified lineages found to be host or geographic specific or both. our results demonstrated a comprehensive view for the evolution of na genes and provided a framework for the inference of evolutionary history of pandemic viruses and for further exploring of viral circulations in multiple hosts. for example, the global pandemics of human h n in , h n in , the pandemic of human h n virus in , the crisis of h n hpai in hong kong in , and swine-origin h n influenza in , all can be mapped onto the lineages and sub-lineages identified in this study. such information will facilitate not only identification of known genetic origins but also early detection of novel influenza a viruses. influenza viruses constantly evolve to avoid the human immune pressure in the process of antigenic drift. through sequencing of viral genomes, the rates and direction of virus evolution can be observed. moreover, comparison of protein sequences allows us to determine amino acid substitutions that are related to immune pressure and antigenic drift. the creation of global influenza genetic databases, along with concurrent development of analytical tools, allows the comparison of multiple influenza virus strains. the main aim of this study was to perform antigenic and genetic comparison of pandemic influenza viruses (h n ) isolated during the - pandemic in ukraine and in other countries. nasopharyngeal swabs and autopsy materials collected from infected patients were received from the areas of ukraine. in addition, field isolates of influenza viruses from the ⁄ season and strain specific serum were used for identification by hemagglutinin inhibition assay. influenza viruses were identified and subtyped using real-time rt-pcr analyses using cdc primers and adopted protocols. sequencing was performed in two world health organization (who) influenza collaboration centers (centers for disease control and prevention, atlanta and national institute for medical research, london). hemagglutinin inhibition assay was conducted using chicken and guinea pig red blood cells following standard who protocols. the all ukrainian isolates of influenza viruses, which were isolated in ukraine during august-november , were identified as a ⁄ california the phylogenetic analyses confirmed the evolutionary relationship between ukrainian isolates and viruses from other countries, which were isolated during the first wave of the pandemic. high genetic and antigenic conservation of pandemic influenza viruses from ukraine and other countries also were demonstrated. considering that the emergence of the novel pandemic influenza strain occurred in countries of northern hemisphere during summer, it was very interesting and significant tracking the dynamics of genetic changes in influenza viruses, which were isolated at the beginning of epidemic and those isolated during the rise of the epidemic in ukraine. influenza a virus causes moderate to severe epidemics annually and catastrophic pandemics sporadically. due to the evasiveness of the influenza virus and the nature of its genome (eight single-stranded and negative-sense rna segments), it is essential to understand the evolution of this important pathogen. influenza virus evolves by two major mechanisms: mutation and reassortment. antigenic and genetic analyses have revealed partially the molecular dynamics of influenza virus evolution. , however, important questions, such as how many genotypes in the influenza a virus, remain unanswered. one of the major issues pertaining to this genotyping problem is how many lineages or sub-lineages can be determined for a subtype and according to what criteria. because of the unique structure of the influenza a viral genome, the computational genotyping methods developed for other viruses cannot be applied to the influenza virus. constructing phylogenetic trees is a powerful technique for the identification of evolutionary groupings (i.e., lineages ⁄ clades). however, for large trees, it is hard to determine how many lineages and the boundaries for each lineage. in this regard, multivariate analysis methods, such as multidimensional scaling (mds) and model-based hierarchical clustering, both taking advantage of dimension reduction and visualization, can complement conventional phylogenetic methods. hemagglutinin (ha), the fastest evolving segment, is recognized as the most important gene in the influenza virus that plays a key role in viral pathogenesis. however, we have only limited knowledge of lineages and sub-lineages occurring in the hemagglutinin (ha) gene of influenza a virus, although much effort has been made in assigning clades or sub-clades in highly pathogenic avian influenza (hpai) virus ha. in this study, both model-based hierarchical clustering and phylogenetic methods were used for sequence analysis. one objective for this study is to explore and develop a more accurate lineage approach for further comprehensive influenza lineage and genotype analyses. a total of hemagglutinin (ha) sequences (approximately nucleotides long), excluding laboratory recombinant sequences, were downloaded from genbank as of march, . sequences were aligned with muscle and mafft. the genetic distance matrix of all pairwise sequences was computed using the k p model under mega . . we then used the distance matrix as input to the cmdscale module in r . . for the mds analysis. the principle coordinates resulting from mds were used for the model-based hierarchical clustering analysis, again in r . . (the r foundation. available at: http://www.r-project.org/). the bayesian information criterion (bic) values were computed based upon ten different statistical data models -eii, vii, eei, evi, vei, vvi, eee, eev, vev, and vvv. the highest bic value was used to determine the number of clusters in the given sequence data. phylogenetic analysis was conducted using maximumlikelihood (ml) in raxml. raxml uses rapid algorithms for bootstrap and maximum likelihood searches and is considered one of the fastest and most accurate phylogeny programs for large-scale sequence analysis. all the analyses were conducted on the supercomputer cluster (holland computing center, http://hcc.unl.edu/main/index.php). the trees were visualized in figtree (version . . ) . lineages and sub-lineages were determined based on both the topology of the ml trees and model-based clustering results. additional information such as hosts, geographical regions, and circulation years were also considered in the classification. we used the same lineage nomenclature as described in, with the following modifications: lineage analysis was conducted for each ha subtype, which agrees with the convention of influenza virologists that ha subtypes were identified in influenza a virus; ha lineages are represented with digits and letters, where the digit(s) represent one of the subtypes and a letter represents a lineage; here, we present sub-lineages or sub-sub-lineages also in digits, with smaller numbers representing earlier lineages or sub-lineages within the same subtype (e.g., lineage occurs earlier than lineage ); the digit is used to indicate inclusion of ancestral viruses in a lineage (or sub-lineage); a dot is used to separate lineages, sub-lineages, and sub-sub-lineages. for example, a. ae means ha subtype, lineage a, and sub-lineage , and sub-sub-lineage . the sub-lineage level can be extended as necessary. the model-based clustering method corroborates commonly used phylogenetic methods in lineage and sub-lineage assignment. here we use the h subtype as an example to show the lineage and sub-lineage assignment. the bayesian information criterion (bic) reaches its maximum when the number of clusters for h equals , regardless of which mode we choose ( figure a ). therefore, based on bic, the optimal number of clusters for the h subtype is . as a result, a total of clusters based upon the vvv model were identified ( figure b) . a significant correlation was found in lineage assignments by the phylogenetic method and the model-based hierarchical clustering method ( figure b,c) . lineages a and b were identified for h , which correspond to north american avian and eurasian avian, respectively. lineage a was further divided into sub-lineages, a. , a. , where a. is the ancestral sub-lineage in a. based on both model-based hierarchical clustering and phylogenetic analyses, a total of distinct lineages were identified among subtypes, averaging out to be ae lineages per subtype ( table ). the majority of the identified lineages were found to be host or geographic specific or both. for example, three lineages, a, b, and c, were identified for ha . lineage a was further divided into two sub-lineages, a. and a. . the a. is swine-specific, whereas a. is a human pandemic h n sub-line- how to accurately identify an evolutionary lineage of influenza a viruses is challenging. one commonly used approach is molecular phylogeny, where phylogenetic trees are constructed, and the tree topology is used for lineage determination. here, we used a bayesian model-based clustering method, along with phylogenetic methods, to decide lineages and sub-lineages of influenza a viruses based upon sequence data. the results demonstrated that the modelbased clustering method corroborates phylogenetic methods and increases the accuracy of lineage assignment. one salient feature of this study is its large-scale analysis of all available influenza a hemagglutinin sequences. a total of distinct lineages and sub-lineages were classified; the majority of them were found to be host or geographic specific. this observation agrees largely with previous findings. we are conducting further analyses of other influenza a segments and expect to identify their lineages and create a comprehensive genotypes database for all influenza a viruses. such information will allow us to detect the genetic origin of newly found viruses, track their genetic changes, and identify potential genome reassortments. a hierarchical nomenclature system has been proposed and adopted for hpai ha clades and sub-clades by who influenza surveillance centers. wan et al. also proposed a hierarchical approach for influenza a viral genotypes system. the work presented here is one of the first steps towards the development of a nomenclature system for influenza a virus lineages (at the segment level) and genotypes (at the genome level). whether the naming system will be accepted and used by the influenza research community is more challenging than the lineage analysis itself. identification of the genetic origins of influenza a viruses will enhance our understanding the evolution and adaptation mechanisms of influenza viruses. the phylogenetic analysis is the traditional approach to identify the influenza progenitor. first, the nucleotide sequences are aligned using multiple sequence alignment methods, such as clustalw, muscle, and t-coffee. second, phylogenetic analysis is performed on these aligned sequences to infer their evolutionary relationship using neighbor-joining (nj), likelihood, or bayesian inference. bootstrap analyses or computation of posterior probability are usually applied to estimate the phylogenetic uncertainty. however, this phylogenetic analysis is time consuming due to intensive computations in multiple sequence alignments and phylogenetic inferences. it is difficult to perform an analysis using this method on a large dataset, for instance, with more than taxa, as is the common case for influenza studies. alternatively, blast is applied to identify the prototype genes in the database. blast determines a similarity by identifying initial short matches and starting local alignments. since influenza viral sequences have very high similarities, especially for most conserved regions, blast usually generates a large number of outputs, which will not be helpful for progenitor identification. since blast is a local sequence alignment, the results from blast may not reflect the global evolutionary information between the sequences. the blast scores cannot be used to define the evolutionary relations between viruses, especially in the context of the entire genetic pool. recently, we have developed a distance measurement method, complete composition vector (ccv), that can calculate genetic distance between influenza a viruses without performing multiple sequence alignments. , we also adapted the minimum spanning tree (mst) clustering algorithm for influenza reassortment identification. the application of this approach in the analyses of pb genes of influenza a virus showed that the integration of ccv and mst allows us to identify the potential progenitor genes rapidly and effectively. based on these results, here we develop a webserver called ipminer for influenza progenitor identification. ipminer can identify potential progenitors for a query sequence against all public influenza datasets within a few minutes. in order to improve the computing efficiency, distance matrices were pre-computed by ccv, and they include for ha (h to ), for na (n to n ), and one for each of the internal gene segments (pb , pb , pa, np, ns, and mp). these pre-computed matrices will be updated weekly. ipminer just needs to compute the query matrices for a query sequence and sequences in the database. the standalone ccv program is also available at http://sysbio.cvm.msstate.edu/ipminer. in order to identify the influenza progenitor genes, ipminer first integrates the query matrix and a corresponding pre-computed matrix into a full distance matrix, which is then clustered by mst clustering algorithm. we adapted the threshold we measured previously in mst, u + nr, where u is the average distance and r is the standard deviation of a cluster. as a result, mst will generate a hierarchical structure for the clusters. in each cluster, we will randomly select viruses or % of the cluster size if this cluster has more than viruses. ipminer will return the viruses with the smallest distances when the search reaches to the lowest level (the largest n) in this hierarchical structure. our analyses have shown that the level has generally yielded good results for influenza a viruses. to visualize the overall mst structure, ipminer applies multi-dimensional scaling (mds) method to project all the viruses in the genetic pool onto a two dimensional graph, and the precursor viruses are marked in different shapes ( figure ). the users can select other prototype viruses from the graph for further phylogenetic analyses. a single job with one query sequence takes < min. the genbank identifiers and associated genetic distances and sequence identities are displayed. the users can download the sequences for the identified precursor viruses as well as those from the prototypes viruses. in addition, for the users' convenience, ipminer generates a phylogenetic tree using nj method implemented in phylip to illustrate the phylogenetic relationship among the query sequence(s), the identified progenitors, and the selected prototypes viruses. the programs in this solution package are written in java. the shell scripts are written in korn shell script in order to achieve high performance. cascading style sheets (css) are used for a consistent look across the pages. this also enables to change the overall design just by replacing the css definition file. php has been used as server side scripting and is written in java. in order to achieve high performance for computing in a genomic scale, we apply hash function or a binary tree, which enables that the precursor identification has a time complexity of o(n). for single queries, the users can visualize the results online. for batch queries of multiple sequences, the results will be sent to the users by e-mail. ipminer has been tested on microsoft internet explorer, mozilla firefox, and safari. the users need javascript to obtain full function of ipminer server. the webserver is available at http://sysbio.cvm.msstate.edu/ipminer. in summary, ipminer webserver has three major computational features for influenza progenitor identification: (i) it calculates the genetic distances through ccv and identifies the viruses with the shortest ccv distances against the query virus to be the progenitor genes; (ii) it projects influenza viruses onto a two dimensional map, which illustrates the global relationship between the progenitor genes and other viruses in the genetic pool; and (iii) it performs phylogenetic analyses between the query virus, the identified progenitor genes, and other selected prototype viruses. ipminer provides a user friendly web service for influenza progenitor identification in real time. the gisaid initiative offers an alternative to current public-domain database models in response to growing needs of the global influenza community for the sharing of genetic sequence and associated epidemiological and clinical data of all influenza strains. gisaid's publicly accessible epifluÔ database is governed by a unique sharing mechanism that protects the rights of the submitter, while permitting ongoing research as well as the development of medical interventions, such as drugs and vaccines. for the gisaid initiative, the max planck institute for informatics (mpii) saarbrücken, germany, has developed a web portal that is accessible at http://www.gisaid.org featuring the gisaid epifluÔ database that offers a unique collection of nucleotide sequence and other relevant data on influenza viruses. the database is based on software by oracle and the dante Ò system by a systems gmbh, germany. extensive metadata are also collected for most isolates. the database provides features for searching, filtering specific datasets for download, and user friendly upload functionality. to uphold gisaid's unique sharing mechanism, all users must positively identify themselves. while access is free of charge, all users agree that they will not attach any restrictions on the data, but will acknowledge both the originator of the specimen and the submitter of the data, and seek to undertake to collaborate with the submitter. all uploaded sequence data are submitted to rigorous curation by the friedrich-loeffler-institute for animal health (fli), germany. the database has been live since september , . among its contributors are all five who collaborating centers for influenza who routinely contribute data in addition to using the epifluÔ database for their semiannual vaccine strain selection. to provide a complete picture of data, all data available in the public domain is routinely imported. as of october , , the rapidly growing gisaid dataset comprises nucleotide sequences (from isolates) with (from isolates) uniquely submitted to this database. software development is underway to continually extend the spectrum of available data analysis tools. the intergovernmental process of the nd world health assembly specifically mentions gisaid as a publicly available database for depositing virus sequence data. starting in , germany's federal ministry of food, agriculture and consumer protection will be the long-term host of the gisaid platform. the mpii will continue to develop the portal and database software and enable gisaid to act as a catalyst for the development of advanced bioinformatics software connected directly to the database. gisaid has become an indispensible resource for the international scientific community on influenza. the consortium will expand its activities and offers to catalyze research and development on a wide variety of issues pertaining to risk analysis, drug development, and therapy of influenza. options for the control of influenza vii ª blackwell publishing ltd, influenza and other respiratory viruses, (suppl. ), - the pandemic h n virus emerged in and spread rapidly throughout the world, principally affecting children and young adults. as this virus is new to the human population, it is important to determine if these influenza infections are more commonly associated with other respiratory pathogens compared to previously circulating influenza strains. co-infecting respiratory viruses may cause increased morbidity in individuals with pandemic h n , and may also be unwanted contaminants in influenza vaccines if original clinical samples containing these adventitious viruses are used to directly inoculate certified cell lines for vaccine production. to examine this issue, stored rna from original clinical samples (nasal swabs, nasal aspirates, throat swabs) from australian and new zealand subjects that were collected in that were positive for pandemic h n and samples collected in that were positive for seasonal influenza by real time pcr assay (using the cdc, usa kits), were subjected to a resplex ii -panel version . (qiagen) pathogen screen. the resplex ii assay detects common respiratory viruses, such as respiratory syncytial viruses (rsv a, b), influenza a and b viruses, parainfluenza viruses (piv - ), human metapneumo-viruses (hmpv), coxsackieviruses ⁄ echovirus (cvev), rhinoviruses (rhv), adenoviruses (adv b, e), coronaviruses (nl , hku , e, oc ), and bocaviruses. resplex ii uses a combination of multiplex rt-pcr, hybridization of pcr onto target specific beads followed by detection using luminex-xmap technology. original clinical samples were received at the center from who national influenza centers, who influenza collaborating centers, and other regional laboratories and hospitals from australia, new zealand, and the asia ⁄ pacific region. most samples were from australia and new zealand. these samples consisted of nasal swabs, nasopharyngeal swabs, nasal washes, throat washes, and throat swabs. all samples were stored at ) °c until rna was extracted. rna was extracted from ll of clinical sample using either the magnapure extraction system (roche, australia) or the qiaxtractor system (qiagen, australia) according to the manufacturer's recommendations with an elution volume of ll and stored at ) °c until used. a ll aliquot of rna was used to amplify the selected influenza virus gene using specific primers and probes as supplied by cdc (atlanta, usa) along with super-script iii platinum one-step rt-pcr reagents (invitrogen, australia). real time pcr detection was performed on a fast system with sds software (applied biosystems, ca, usa). a cut off of a cycle threshold (c t ) of or below was considered positive. resplex ii panel ver . detection the qiagen molecular differential detection (mdd) system was used, which combines qiaplex amplification (multiplex rt-pcr) with detection on the liquichip workstation (luminex's xmap microsphere based multiplexing system) and qiaplex mdd software according to the manufacturer's instructions. a low level cutoff was used ( ) to obtain maximum sensitivity. from the clinical specimens that were positive for influenza from by real time pcr, there were ( %) a(h n ) seasonal influenza viruses, ( ae %) a(h n ) viruses, ( %) b viruses, and ( ae %) viruses which were influenza a positive, but could not be typed. clinical samples from selected to study were all influenza a(h n ) pandemic positive by real time pcr. detection of influenza virus in respiratory samples was much lower with the resplex ii assay (using a low cut off of units) for pandemic influenza a virus ( ⁄ ; sensitivity ae %) and to a lesser extent for seasonal influenza a ( ⁄ ; sensitivity of ae %) and b viruses ( ⁄ ; sensitivity of ae %) when compared to real time pcr. there were relatively few co-infecting respiratory viruses with either pandemic h infections in ( ae %) or seasonal influenza infections in ( ae %) ( table ). the most common dual infection seen with pandemic h n viruses and seasonal b viruses was with cvev ( ⁄ ; and ⁄ ; , respectively) while for a(h ) viruses there were no dominant co-infecting viruses ( table ). in one case was detected with three respira- tory pathogens in the same sample, a year old female who had pandemic h n , cvev, and rhv, and in a seasonal influenza sample, one case with a triple infection was detected (bocavirus, piv and influenza b). the median age of subjects with co-infections was younger for both pandemic h n with a median age of years (range: months to years), compared to the full sample set which had a median age of years (range: months to years), while for the patients from with seasonal influenza viruses with co-infections they had a median age of ae years (range: months to years) compared to all samples which had a median age of years (range: months to years). there was good concordance in detecting influenza a and b in respiratory samples collected in between real time rt-pcr and the resplex ii system ( % versus > ae % for seasonal influenza a and b respectively). this data compares well with other studies such as li et al. who found that resplex ii had ae % sensitivity and % specificity for seasonal influenza a viruses and ae % sensitivity and % specificity for influenza b viruses. in contrast, the present study found only ae % sensitivity for the resplex ii detection of influenza a with the samples that were positive for pandemic h n by real time rt-pcr. a recent study by rebbapragada et al. also showed lower sensitivity for pandemic h n viruses in nasopharyngeal samples with the resplex ii system ( % sensitivity and % specificity) compared to other commercial platforms seeplex rvp ( % sensitivity and % specificity) and luminex rvp ( % sensitivity and % specificity). interestingly the latest version of the resplex system offered by qiagen the resplex ii plus panel ruo now has a separate target for the pandemic h n virus (mexico ). in terms of detection of other respiratory viruses such as piv- , piv- , rsv and hmpv, high sensitivities ( ae %, ae %, ae %, and %, respectively) and specificities ( ae - %) compared to taqman rt-pcr have been reported from testing of nasal wash and nasopharyngeal clinical samples. in both the seasonal influenza positive and the pandemic h n positive (by real time rt-pcr) clinical specimens, few other respiratory viruses were detected. only of the samples had another virus detectable and one had two other viruses, while in out had another virus and one had two other viruses detected from a total of influenza virus positive samples collected in each year. enteroviruses, coronaviruses, and parainfluenza viruses were most often found with both seasonal and pandemic infections. younger age appeared to be associated with co-infections with those subjects in with dual infections having a median age of only years compared to the study groups years; and similarly for , the median age for subjects with dual infections was only ae years compared to the study groups' median age of years. a study by chong et al. on nasopharyngeal swabs collected during - using resplex ii and luminex xtag rvp fast, they found dual respiratory virus infections in ⁄ ( ae %) of samples and only ( ae %) with triple respiratory viral infections; however, these were from cases with any combination of multiple respiratory viruses not necessarily influenza, although influenza positive cases were the most common respiratory virus detected ( ae % of all positive samples). given the low level and variety of viral co-infections along with both seasonal and pandemic influenza seen in this study, it is unlikely that influenza infections predispose subjects to particular respiratory viruses, but may still allow bacterial colonization, such as has been seen with severe and fatal cases with pandemic h n with various bacteria including streptococcus pneumoniae, streptococcus pyogenes, staphylococcus aureus, or haemophilus influenzae. , low levels of other respiratory viruses along with the finding that certain cell lines (like the mdck -cells used in this study) do not propagate a number of these viruses (e.g. rsv a and b, rhinoviruses, coronaviruses), but do propagate others (e.g. parainfluenza ) should make testing for unwanted viruses that might be co-isolated with influenza viruses more focused and hence easier to detect and eliminate this isolate for future vaccine production. global influenza surveillance is one of the most important approaches to combat spread of disease. current laboratory methods for characterizing influenza are time-consuming and labor-intensive, and few viral strains undergo full characterization. even fewer strains from domestic poultry and swine or from wild aquatic birds are wellcharacterized. these strains are important for global surveillance since they are thought to be the precursors to pandemic influenza strains. we have designed a highthroughput global bio laboratory to address these surveillance needs. the goal of this project was to develop highspeed and high-volume laboratory capabilities for extensive surveillance and rapid and accurate detection and analysis of influenza. the workflow consists of surveillance, sample transportation, laboratory testing, data management and analysis. five robotic systems have been designed for this laboratory: sample accessioning, biobanking, screening, viral culture, and sequencing. sample accessioning logs barcodes, centrifuges, and aliquots samples are then sent to biobanking. the robotic biobank stores samples at ) °c and reformats tubes for screening. the screening system extracts rna and confirms the presence and subtype of influenza. aliquots of positive samples are sent to the viral culturing system for scale-up. finally, cultured samples are extracted and sent to the sequencing system for full genome sequencing. the sample accessioning, sequencing, and biobanking systems have been built, delivered, and validation processes are currently being completed. robotic screening and culturing systems have been fully designed and are ready to be built. a biosafety level -enhanced containment laboratory was built to enable the flow of samples containing highly pathogenic avian influenza viruses. in full operation, this approach to surveillance is designed to enable the sequencing of up to full virus genomes per year, more than the total of all full influenza genomes sequenced to date. the design of a robotic laboratory for influenza surveillance presents unique challenges and opportunities. before a robotic system is built, each assay is worked out on the bench top, each movement of the plates and reagents is defined, and the laboratory information management system (lims) must be able to address each step of the process. alternate assays are conceived for processes that are not automation-friendly. waste streams, worker safety, and space constraints are considered. each possibility is taken to reduce processes that have the potential to aerosolize or cross-contaminate influenza samples. instruments must be found that fit the capabilities needed. detailed specifications for each of the robotic systems were written including all the parameters listed above. once the systems are built, a long validation process takes place where the processes and instruments in each system are adjusted to function together properly. finally, a validation study is performed to ensure that the system is able to produce useful data for influenza research. the entire process takes months from start to finish for each robotic system and requires complete cooperation from a diverse team of researchers. the accessioning system logs initial sample information with the lims system. samples arrive in barcoded cryotubes. the liquid handler brings all samples up to a common volume and clarifies samples by centrifugation. samples are then transferred from screw-cap sample vials into storage plates containing individually punchable storage tubes. each tube ( ae ml) is individually identifiable with a d barcode on the bottom. six archive aliquots are made, and tubes are individually weld-sealed for storage. tips for aspiration are fixed and undergo a high-pressure plasma process between each use to sterilize tips and destroy nucleic acids. samples are stored at ) °c. each module has a capacity of remp plates or $ samples. the automated freezer system can assemble requested samples as -well plates while samples remain frozen. the screening system uses magnetic bead extraction chemistry, real-time pcr, and a liquid handling system to extract samples, confirm and quantify the presence of influenza, and reformat extracted samples for input into the sequencing system. serotype of human influenza samples will be performed by real-time pcr. many samples will not have enough material for further analysis and will need to be scaled up. the culturing system combines incubators, a liquid handling platform, plate reader, and real-time pcr to culture, monitor growth, harvest, and quantify influenza. when the system is not being used for culture and scale-up, it can be used to assay previously cultured influenza samples for drug resistance. a challenge to sequencing large numbers of influenza samples is the manpower required for sample preparation. the sequencing system has the capacity to prepare up to samples for sequencing per year for sanger sequencing. sanger sequencing was chosen because it is well-established for influenza surveillance, and automation-friendly. the system is designed to work with multiple primer sets ( , , ) . robotic systems all report to the lims. each process completion, plate movement, and data point are entered and checked by an online, web-based lims. status updates, notification, reporting, and data analysis can be achieved without entering the bsl containment facility. routine data analysis such as determining whether a cultured sample is ready to be harvested will be performed by the lims. complex data analysis, while still requiring significant human input, will be made easier by the data-acquisition functions of the lims. the implementation of a high-throughput influenza surveillance laboratory will provide an influenza research and response capacity that far exceeds what is available today. with the addition of each new system, we add a new capability to the influenza community and new opportunities to foster partnerships and collaborations with government, foundations, businesses, and academic institutions. this laboratory will not only enable cutting edge research, but will also enable a more effective response of near real-time surveillance during a pandemic outbreak. pandemics of and were believed to arise from avian influenza viruses. the tropism of avian and human seasonal influenza viruses for the human lower respiratory tract deserves investigation. the target cell types that support replication of avian influenza a viruses in the human respiratory tract in the early stages of clinical infection have not well defined. in a previous autopsy studies of human h n disease, influenza a virus were found to infect alveolar epithelial cells and macrophages. in this study, viral infectivity and replication competence of human and high and low pathogenic avian influenza viruses were systematically investigated in the human conducting and lower respiratory tract using ex vivo organ cultures. we compared the replication kinetics of human seasonal influenza viruses (h n and h n ), low pathogenic avian influenza viruses (h n , h n ) with that of the highly pathogenic h n viruses isolated from human h n disease. a range of human seasonal influenza a viruses of subtypes h n and h n viruses were included in this study from to . two isolates of low pathogenic avian influenza a (lpai) (h n ) viruses from different virus lineages isolated from poultry in hong kong in , a low pathogenic influenza a (h n ) virus isolate from wild ducks in hong kong in , and two virus isolates of highly pathogenic avian influenza (hpai) a subtype h n were included. fragments of human bronchi and lung were cut into multiple - mm fragments within hours of collection and infected in parallel with influenza a viruses at a titer of tcid ⁄ ml and as control cultures were infected with ultraviolet light inactivated virus. these tissues fragments were infected for hours and washed twice with pbs and incubated for , , and h at °c. the bronchial tissue was cultured in an air-liquid interface using sponge. viral yield was assessed by titration in mdck cells. one part of the infected tissue were fixed in formalin and processed for immunohistochemistry for influenza antigen. other part of infected tissue was homogenized and underwent rna extraction, and the expression of influenza virus matrix gene was measured by quantitative rt-pcr. human bronchus ex vivo cultures supported human seasonal influenza virus to replicate efficiently. avian influenza h n virus replicated, although less efficiently than that of seasonal influenza viruses, whereas hpai h n did not productively replicate in ex vivo cultures of human bronchus. this is in agreement with our previous finding in the well-differentiated bronchial epithelial cells in vitro. on the other hand, human lung ex vivo cultures supported prominent productive replication of human seasonal influenza h n ( figure a ) and hpai h n ( figure f ) viruses. lpai, such as h n ( figure c -d) and h n ( figure e ), also replicated productively, but with a lower viral yield. surprisingly, the replication of human influenza h n viruses ( figure b ) across the last three decades was greatly inhibited. there are clear differences in viral tropism of human seasonal and avian influenza viruses for replication in the human bronchus and lung. hpai h n virus can infect and productively replicate in the lower lung, which may account for the severity of human h n disease, but not in the conducting airways. surprisingly, there are marked differences in the replication competence of seasonal influenza viruses in ex vivo lung tissues, with influenza h n viruses being able to replicate efficiently while h n viruses do not. this may be related to the more strict siaa - gal binding preference of h n viruses. on the other hand, the efficient replication of influenza h n viruses in the alveolar spaces indicates factors other than tissues tropism alone play a role in the differences in disease severity between human seasonal h n and avian h n virus infections. pre-mrnas of the influenza a virus m and ns genes are poorly spliced in virus-infected cells. by contrast, in influenza c virus-infected cells, the predominant transcript from the m gene is spliced mrna. the present study was performed to investigate the mechanism by which influenza c virus m gene-specific mrna (m mrna) is readily spliced. ribonuclease protection assays showed that the splicing of m mrna in infected cells was much higher than that in m gene-transfected cells, suggesting that viral protein(s) other than m gene-translational products facilitates the splicing of viral mrnas. the unspliced and spliced mrnas of the influenza c virus ns gene encode two nonstructural (ns) proteins, ns (c ⁄ ns ) and ns (c ⁄ ns ), respectively. the introduction of translational premature termination into the ns gene, which blocked the synthesis of c ⁄ ns and c ⁄ ns proteins, drastically reduced the splicing of ns mrna, raising the possibility that c ⁄ ns or c ⁄ ns enhances the splicing of viral mrnas. the splicing of influenza c virus m mrna was increased by co-expression of c ⁄ ns , whereas it was reduced by co-expression of influenza a virus ns protein (a ⁄ ns ). the splicing of influenza a virus m mrna was also increased by co-expression of c ⁄ ns , whereas it was inhibited by that of a ⁄ ns . these results suggest that influenza c virus ns , but not a ⁄ ns , can up-regulate the splicing of viral mrnas. pre-mrnas of the influenza a virus m and ns genes are poorly spliced in virus-infected cells. , the inefficient splicing of viral pre-mrnas can be understood partly by the fact that influenza a virus ns protein is associated with spliceosomes and inhibits pre-mrna splicing. , cis-acting sequences in the ns transcript also negatively regulate splicing. by contrast, in influenza c virus-infected cells, the predominant transcript from the m gene is spliced mrna. the present study was performed to investigate the mechanism by which influenza c virus m gene-specific mrna (m mrna) is readily spliced. the yamagata ⁄ ⁄ strain of influenza c virus was grown in the amniotic cavity of -day-old embryonated hen's eggs. cos- and t cells were cultured in dulbecco's modified eagle's medium containing % fetal calf serum. subconfluent monolayers of cos- cells were transfected with pme s containing influenza c virus m gene cdna using the lipofectamine procedure and then incubated at °c. total rna was extracted from both the transfected cells and cells infected with c ⁄ yamagata ⁄ ⁄ virus using the rneasy mini kit (qiagen). ribonuclease protection assay was performed using a ribonuclease protection assay kit rpa iii (ambion). briefly, a [ p]-labeled influenza c virus rna -specific rna probe (vrna sense) was synthesized by in vitro transcription and hybridized with the total rna at °c overnight. hybrids were digested with rnase a ( ae u) and rnase t ( u) at °c for minutes and then analyzed on a % polyacrylamide gel containing m urea. hmv-ii cells infected with c ⁄ yamagata ⁄ ⁄ and cos- cells transfected with pme s expressing influenza c virus ns were fixed with carbon tetrachloride at various times after infection and transfection, respectively. the cells were then stained by an indirect method using anti-gst ⁄ ns serum as the primary antibody and fluorescein isothiocyanate-conjugated goat anti-rabbit igg (seikagaku kogyo) as the secondary antibody. the splicing efficiency of influenza c virus m gene-specific mrna (m mrna) in infected cells was higher than that in m gene-transfected cells the ratio of m encoded by a spliced m mrna to cm encoded by an unspliced m mrna in influenza c virusinfected cells was about times larger than that in m gene-transfected cells. ribonuclease protection assays showed that the splicing of m mrna in infected cells was much higher than that in m gene-transfected cells (figure ). these data suggest that viral protein(s) other than m gene-translational products facilitates viral mrna splicing. the influenza c virus ns gene translational product may up-regulate the splicing of viral mrnas the unspliced and spliced mrnas of the influenza c virus ns gene encode two nonstructural (ns) proteins, ns (c ⁄ ns ) and ns (c ⁄ ns ), respectively. the introduction of translational premature termination into the ns gene, which blocked the synthesis of c ⁄ ns and c ⁄ ns proteins, drastically reduced the splicing of ns mrna, suggesting that c ⁄ ns or c ⁄ ns enhances viral mrna splicing. immunofluorescent staining showed that ns localized in the nucleus in the early phase of infection, and was distributed in both the nucleus and cytoplasm in the late phase of infection, raising the possibility that influenza c virus ns protein plays a role in viral mrna splicing that occurs in the nucleus. the splicing of influenza c virus m mrna was increased by co-expression of c ⁄ ns , whereas it was reduced by co-expression of influenza a virus ns protein (a ⁄ ns ) (figure a ). the splicing of influenza a virus m mrna was also increased by co-expression of c ⁄ ns , though it was inhibited by that of a ⁄ ns ( figure b ). these results suggest that influenza c virus ns , but not a ⁄ ns , can up-regulate the splicing of viral mrnas. in influenza a virus-infected cells, splicing is controlled so that the steady-state amount of spliced mrnas is only - % of that of unspliced mrnas. , the mechanisms by which influenza a virus ns pre-mrnas are poorly spliced have been investigated and the following confirmed. influenza a virus ns protein associates with spliceosomes and inhibits pre-mrna splicing. , two cis-acting sequences in the ns transcript (positions - in the intron and positions - in the ¢ exon region) inhibit splicing. by contrast, influenza c virus m gene-specific mrna (m mrna) is efficiently spliced in influenza c virus-infected cells. in this study, we examined the mechanism by which influenza c virus m mrna is efficiently spliced and the regulatory mechanism of the splicing of ns gene-specific mrna (ns mrna). the introduction of a translational pre-mature termination into the influenza c virus ns gene, thereby blocking the synthesis of influenza c virus ns (c ⁄ ns ) and ns (c ⁄ ns ) proteins, drastically reduced the splicing rate of ns mrna. we further examined whether c ⁄ ns potentially facilitates viral mrna splicing. the splicing rate of m mrna of influenza c virus was increased by co-expression with c ⁄ ns , whereas it was reduced by co-expression with influenza a virus ns protein (a ⁄ ns ) (figure a ). the splicing of influenza a virus m gene-specific mrna was also increased by co-expression with c ⁄ ns , though it was inhibited by co-expression with a ⁄ ns ( figure b ). these results suggest that influenza c virus ns can facilitate viral mrna splicing, but in no way inhibit it, which is in striking contrast to the inhibitory effect of influenza a virus ns on pre-mrna splicing. , the mechanism for splicing enhancement by c ⁄ ns also remains to be determined. we speculate that c ⁄ ns may interact with some host proteins involved in splicing, thereby leading to an up-regulation in splicing, or that c ⁄ ns may bind to pre-mrna, increasing its accessibility to the spliceosome. the spliced mrna of the influenza c virus m gene encodes the m protein, which plays an important role in virus formation and determines virion morphology. , therefore, it is speculated that the mechanism for efficient splicing of m mrna, which provides the m protein necessary for virus assembly in a redundant amount, has been maintained in the influenza c virus. by contrast, unspliced mrna from the influenza c virus m gene encodes the cm ion channel, which is permeable to chloride ions, and also has ph-modulating activity. although the role of the influenza c virus cm ion channel in virus replication remains to be determined, it is conceivable that the over-expression of the cm protein has a deleterious effect on virus replication since the fact that a high level of influenza a virus m protein expression inhibits the rate of intracellular transport of the influenza a virus ha protein and other integral membrane glycoproteins has been demonstrated. if this is the case, efficient splicing of m mrna may control the amount of cm synthesized to optimize virus replication. therefore, we speculate that efficient splicing of m mrna leads to a high level of m expression and the reduced expression of cm , thereby creating conditions that are optimal for virus replication. in this study, we provided evidence that c ⁄ ns facilitates the splicing of m mrna. furthermore, c ⁄ ns may regulate the splicing efficiency of its own ns mrna during infection, controlling the amount of c ⁄ ns and c ⁄ ns proteins in infected cells. c ⁄ ns plays an important role in the nuclear export of vrnp, and is also associated with vrnp in the later stages of infection in virus-infected cells and is incorporated into virions, suggesting that c ⁄ ns is involved, not only in the sorting of vrnp into the assembly site, but also in virus assembly. therefore, it is likely that there is a mechanism by which an appropriate amount of c ⁄ ns is provided during infection to accomplish these functions. in conclusion, c ⁄ ns , which enhances the splicing of viral mrna, may regulate both the expression level of m gene-derived m and cm proteins, and that of ns gene-derived ns and ns proteins, thereby leading to optimal virus replication. propagation of the human influenza viruses in embryonated hen's eggs always results in a selection of variants with amino acid substitutions in the hemagglutinin (ha) that affect viral receptor-binding characteristics (reviewed ). brookes et al. recently studied infection in pigs using the egg-grown virus that contained a mixture of the original a ⁄ california ⁄ ⁄ (h n pdm) and its two egg-adaptation mutants with single amino acid substitutions d g and q r ( and in h numbering system). only the original virus and the variant with g were detected in the directly inoculated animals, indicating that the variant with r failed to infect. only the original virus was detected in nasal secretions of contact infected pigs, suggesting that the d g mutant failed to transmit. in contrast, there was an apparent selection of the d g mutant in the lower respiratory tract samples from directly inoculated pigs. the d g substitution is of a special interest as it can emerge during virus replication in humans and was associated with severe and fatal cases of pandemic influenza in - - and . here we compared phenotypic properties of the original clinical isolate of h n pdm virus a ⁄ hamburg ⁄ ⁄ and its d g and d r mutants to explain observed effects of these mutations on virus replication in swine and to predict their potential effects on virus replication in humans. a ⁄ hamburg ⁄ ⁄ (ham) was isolated from clinical material by two passages in mdck cells. the virus was passaged twice in -day-old embryonated hen's eggs and plaqued in mdck cells. the plaques were amplified in mdck cells and the sequences of the viral ha were determined. the variants with single mutation d g and q r were aliquoted and designated ham-e and ham-e , respectively. the receptor-binding specificity of the viruses was assessed by assaying their binding to desialylated-resialylated peroxidase-labeled fetuin containing either a - -linked sialic acid ( - -fet) or a - -linked sialic acid ( - -fet). in brief, viruses adsorbed in the wells of -well eia micro plates were incubated with serial dilutions of - -fet or - -fet, and the amount of bound fetuin probe was quantified by peroxidase activity. the binding data were converted to scatchard plots (a ⁄ c versus a ), and the association constants of the virus-fetuin complexes were determined from the slopes of these plots. viral cell tropism and replication efficiency in human airway epithelium were studied using fully differentiated cultures of human tracheo-bronchial epithelial cells (htbe). , to determine cell tropism, cultures were infected at a moi , fixed hours after infection, and double immuno-stained for virus antigen and cilia of ciliated cells. infected cells were counted under the microscope ( · objective with oil immersion) in the epithelial segment that included - consecutive microscopic fields containing between % and % ciliated cells relative to the total number of superficial cells. percentages of infected ciliated cells and infected non-ciliated cells relative to the total number of infected cells were calculated. ten segments per culture were analyzed and the results were averaged. to compare growth kinetics of ham and ham-e, replicate htbe cultures were infected with plaque-forming units of the viruses followed by incubation at °c under airliquid interface conditions. at , , and hours postinfection, we added dmem to the apical compartments of the cultures and incubated for minutes at °c. the apical washes were harvested, stored at ) °c, and analyzed simultaneously for the presence of infectious virus by titration in mdck cells as described previously. the non-egg-adapted h n pdm virus ham, similarly to the seasonal human virus a ⁄ memphis ⁄ ⁄ (h n ), bound to - -fet ( figure a ) and did not show any significant binding to - -fet. this result contrasted with the binding of h n pdm viruses to several - -specific probes in carbohydrate microarray analysis. reduced avidity of virus interactions with soluble glycoprotein in solution as compared to its binding to the probe clustered on the microarray surface could account for these differences in the assay results. the d g mutant ham-e differed from the parent virus by its ability to bind to -fet and by its reduced binding to -fet. the q r mutant only bound to - -fet, although less strongly than did the avian virus a ⁄ duck ⁄ alberta ⁄ ⁄ (h n ). the viral cell tropism in htbe cultures ( figure b ) correlated with receptor specificity. ham and mem ⁄ showed a typical human-virus-like tropism , with preferential infection of non-ciliated cells (< % of infected cells were ciliated). the mutant with r and control duck virus displayed a typical avian-virus-like tropism (preferential infection of ciliated cells). the d g mutant displayed a cell tropism that was intermediate between those of human and avian viruses; in particular, this mutant infected significantly higher proportion of ciliated cells than ham and mem ⁄ . observed alteration of receptor specificity and cell tropism ( figure ) suggested that egg-derived mutations can affect replication of the h n pdm virus in human airway epithelium. to test this, we first compared the capacity of the viruses to initiate infection in htbe cultures. replicate cultures were infected with identical doses of the viruses, fixed hours post-infection, and immuno-stained for viral antigen. under these conditions, ham and ham-e infected comparable numbers of cells, whereas ham-e infected at least times less cells (data not shown). this result indicated that the mutation q r markedly impaired the ability of ham-e to infect human airway epithelial cultures. we next compared two other viruses ham and ham-e for their multi-cycle replication in htbe cultures and found that the original virus reached threefold higher peak titers hours post infection than did the d g mutant ( figure ). the d g mutation in h n pdm virus facilitates virus binding to - -linked receptors and alters viral cell tropism in human airway epithelium. these changes could account for increased replication of the d g mutant in the lower respiratory tract in humans - and pigs and correlation of this mutation with severe pulmonary disease. [ ] [ ] [ ] [ ] [ ] the d g mutant replicates less efficiently in human airway cultures than the original virus. this finding correlates with an apparent lack of transmission of variants with g in humans and pigs. egg-derived mutation q r abolishes virus binding to - -linked receptors and strongly decreases infection in cultures of human airway epithelium. this result agrees with poor infectivity of the q r mutant in pigs and highlights potential pitfalls of using egg-adapted viruses with this mutation for the preparation of live influenza vaccines. nin-esterase-fusion (hef), nucleoprotein (np), matrix (m ) protein, cm , and the non-structural proteins ns and ns . , cm is the second membrane protein of the virus and is encoded by rna segment (m gene). [ ] [ ] [ ] [ ] [ ] [ ] it is composed of three distinct domains: a -residue n-terminal extracellular domain, a -residue transmembrane domain, and a -residue cytoplasmic domain. , , it is abundantly expressed at the plasma membranes of infected cells and is incorporated in a small amount into virions. , cm forms disulphide-linked dimers and tetramers, and is posttranslationally modified by n-glycosylation, palmitoylation, and phosphorylation. [ ] [ ] [ ] analyses of a number of cm mutants revealed the positions of the amino acids involved in the posttranslational modifications. , evidence was obtained that the n-glycosylation was not required for either the formation of disulfide-linked multimers or transport to the cell surface, and that none of dimer-or tetramer-formation, palmitoylation or phosphorylation was essential to the transport of cm to the cell surface. in the present study, in order to investigate the effect of cm palmitoylation on influenza c virus replication, we generated a cm palmitoylation-deficient influenza c virus, in which a cysteine at residue of cm was mutated to alanine, and examined the viral growth and viral protein synthesis in infected cells. t and hmv-ii cells were maintained as described previously. , llc-mk cells were maintained at °c in minimal essential medium with % foetal bovine serum and % calf serum. monoclonal antibodies (mabs) against the hef, np, and m proteins of c ⁄ ann arbor ⁄ ⁄ (aa ⁄ ), and antisera against the aa ⁄ virion and the cm protein were prepared as described previously. , [ ] [ ] [ ] the seven pol i plasmids for the expression of viral rnas of aa ⁄ , and the nine plasmid dnas for the expression of the influenza c viral proteins were reported previously. , plasmid dna, ppoli ⁄ cm -acy(-), in which -tgt- of the m gene was replaced with -gct- , was constructed based on ppoli ⁄ m. to generate a recombinant wild-type (rwt) virus, the above-mentioned plasmids were transfected into t cells as described previously. to rescue a mutant virus, rcm -c a, a recombinant influenza c virus lacking a cm palmitoylation site, the plasmid ppoli ⁄ cm -acy(-), instead of ppoli ⁄ m, was transfected together with the other plas-mids. at hours posttransfection (p.t.), the respective culture medium of the transfected- t cells was inoculated into the amniotic cavity of -day-old embryonated chicken eggs, and a stock of the recombinant virus was prepared. the infectious titres of the stocked recombinant viruses and the supernatants of recombinant-infected hmv-ii cells were determined according to the procedure reported previously. radioimmunoprecipitation hmv-ii cells infected with recombinants were labeled with [ s]methionine or [ h]palmitic acid. cells were then disrupted and subjected to immunoprecipitation with the indicated antibodies. the immunoprecipitates obtained were then analysed by sds-page on ae % gels containing m urea, and processed for fluorography. flotation analysis was performed according to the procedure described previously. to examine whether the cm protein without palmitoylation is synthesized in rcm -c a-infected cells, hmv-ii cells infected with the recombinants were subjected to , and the lysates of the cells were immunoprecipitated with anti-cm serum and analysed by sds-page. as shown in figure , the cm protein was synthesized both in the rwt-and rcm -c a-infected cells, but no incorporation of [ h]palmitic acid into the cm proteins synthesized in the rcm -c ainfected cells was observed, indicating that cm in the rcm -c a-infected cells was not palmitoylated. the rwt or rcm -c a viruses were infected to hmv-ii cells at an m.o.i. of and incubated at °c for up to hours. the infectious titres (p.f.u. ⁄ ml) of rwt were approximately -to -fold higher than those of rcm -c a at - hours p.i. (data not shown), indicating that rwt grew more efficiently than did rcm -c a. thus palmitoylation of cm appears to have some effect on the generation of infectious virions in cultured cells. to investigate the reason(s) for the difference in growth kinetics between the two recombinants, we analysed viral proteins synthesized in the infected hmv-ii cells. pulsechase experiments of hmv-ii cells revealed no significant differences in the synthesis and maturation of the hef, np, m , and cm proteins between the rwt-and rcm -c a-infected cells (data not shown). the infected cells pulse-labeled and chased were respectively immunoprecipitated with anti-cm serum in the presence of mm iodoacetamide and analysed by sds-page in non-reducing condition. in both populations of infected cells, several bands corresponding to cm a-monomer, -dimer, and -tetramer, as well as cm b-dimer and -tetramer were detected (data not shown). these results demonstrate an absence of any significant differences between palmitoylation-deficient cm and authentic cm in terms of conformational maturation and transport in infected cells. membrane flotation analysis revealed that no significant differences in the kinetics of the hef, m , and cm proteins were observed between rwt-and rcm -c ainfected cells (data not shown). in contrast, a slight difference in np kinetics was observed. the pulse-labeled np proteins were recovered in the bottom fractions in both rwt-and rcm -c a-infected cells. in the chase experiment, the amount of membrane-associated np proteins in fractions and was % of the total np in the rwt-infected cells, which was higher than that ( %) in the rcm -c a-infected cells (data not shown). this finding may suggest that the affinity of the np protein, presumably representing the viral ribonucleoprotein (vrnp) complex, to the plasma membrane in the rcm -c ainfected cells is lower than that in rwt-infected cells, leading to the less efficient generation of infectious virions. since cm is structurally similar to m , an influenza a virus membrane protein known to be involved in infectious virus production, [ ] [ ] [ ] [ ] [ ] it is possible that the cytoplasmic tail of cm participates in the genome packaging through interaction with vrnp. in the present study, we showed that the affinity of np to the plasma membrane of rcm -c a-infected cells was slightly lower than that to the plasma membrane of rwt-infected cells. this observation may suggest that palmitoylation of cm is involved in the viral ribonucleoprotein (vrnp) incorporation, leading to efficient infectious virion generation. we hypothesize that palmitoylation contributes to proper regional structure formation in the cm cytoplasmic tail, which is competent to recruit vrnp efficiently into virions. alternatively, the cm cytoplasmic tail without palmitoylation is not likely to reach the proper conformation, resulting in reduced interaction with vrnp and less efficient generation of infectious progeny virions. the questions of if and how the m protein is involved in the interaction between the cm cytoplasmic tail and np remains to be clarified. we showed that cm synthesized in rcm -c ainfected cells was oligomerized and transported to the cell surface. this finding is consistent with the previous observation that palmitoylation is not required for the transport of cm to the cell surface in cm -expressing cos- cells. however, the use of reverse-genetics system has enabled us to conclude that the palmitoylation of cm is required for efficient infectious virus production. this suggests that the significance of the other posttranslational modifications of cm during virus replication can be clarified using recombinant viruses lacking the respective modification sites. sialic acid (sia) linked glycoproteins are the classical influenza receptors for influenza virus haemagglutinin to bind. the distribution of sia on cell surfaces is one of the determinants of host tropism, and understanding its expression on human cells and tissues is important for understanding influenza pathogenesis. previous research has shown the differences in apical versus basolateral infection and release of different influenza virus from polarized epithelial cells and correlated this with sialic acid distribution in the human respiratory tract. moreover, mass spectrometric analysis was recently employed to elucidate the glycans present in the tissue in a higher resolution in human lung. the objective of this study was to examine in detail the distribution of these sia-linked glycans at the cellular level by the use of confocal microscopy. human primary type i-like and type ii pneumocytes were isolated from human non-tumor lung tissue by tissue fragmentation, percoll density gradient centrifugation, and magnetic cell sorting. the cells were seeded on coverslips and maintained in small airway growth medium. when confluence was reached, cell monolayers were fixed with % paraformaldehyde. we used the plant lectins, sambucus nigra glutinin (sna) from roche which binds to siaa - gal, maackia amurensis agglutinin (maa)i and maaii from vector lab, which bind the siaa - gal linked glycans using vector red as fluorescent chromogen. the cells were counter-stained with dapi or with fitc-conjugated antibody against endoplasmic recticulum (protein disulfideisomerase, pdi). the cells were imaged with multi-photon excitation laser scanning microscopy using zeiss lsm. the optical cross-section pictures were reconstructed by zeiss lsm meta. we found that there was more binding of maai and ma-aii to type ii pneumocytes than type i-like pneumocytes and more overall binding of these lectins than binding of sna ( figure ). in keeping with results from other polarized cells there was more binding to the apical than basolateral aspect, thus, explaining the previously published data on apical versus basolateral infection. as sialic acid has been implicated in the targeting of proteins to the surface, the relative lack of sialic acid on the basolateral aspect can explain why there is little seasonal influenza virus dissemination to the systemic circulation in human infections. furthermore, though there was little binding of sna to the figure . primary human type i-like and type ii pneumocytes stained with lecins (red), pdi (green), and dapi (blue) and imaged captured with confocal microscope. apical or basolateral aspects of the pneumocytes, the experimental findings of infection by influenza h n virus that has a strict siaa - gal tropism suggests that there are siaa - gal glycans present, which are not readily bound by the lectin sna. the in vitro model of primary human type i-like and type ii pneumocytes system formed a polarized epithelium that has a similar lectin distribution to human alveoli in vivo which demonstrated that it is a physiologically relevant model to study the tropism and pathogenesis of influenza a virus. human disease caused by highly pathogenic avian influenza (hpai) h n virus is associated with fulminant viral pneumonia and mortality rates in excess of %. cytokine dysregulation is thought to contribute to its pathogenesis. , we previously found delayed onset of apoptosis in h n infected human macrophages and, therefore, a longer survival time of the target cells for prolonged virus replication and cytokine and chemokine secretion, which may contribute to the pathogenesis of h n disease in humans. as bronchial and alveolar epithelial cells are target cells of influenza virus because of their proximal physiological location and interaction with macrophages, we further investigated if the differential onset of apoptosis could be found in influenza h n and seasonal influenza h n infected human respiratory epithelia. we dissected the apoptotic pathways triggered by influenza virus infection. seasonal influenza h n virus (a ⁄ hk ⁄ ⁄ ), a low pathogenic avian influenza h n lineage isolated from poultry (a ⁄ quail ⁄ hk ⁄ g ⁄ ), and two virus isolates of hpai a subtype (a ⁄ hk ⁄ ⁄ and a ⁄ vn ⁄ ⁄ ) were included. primary human bronchial and alveolar epithelial cells were infected with influenza viruses at moi of and the cell monolayer was collected at , , and hours post infection for tunel assay, and supernatant were collected for ldh assay. fragments of human lung tissues were cut into multiple - mm fragments within hours of collection and infected with influenza a viruses at a titer of tcid ⁄ ml. these tissues fragments were infected for hours and incubated for hours at °c. one part of the infected tissue was fixed in formalin and processed for immunohistochemistry for influenza antigen, and the other part was homogenized and underwent rna extraction. apoptosis cdna superarray platform (sabioscience) was employed to conduct apoptosis pathway analysis. in bronchial epithelial cells, seasonal influenza h n virus induced a high percentage of apoptotic cells by tunel assay at , , and hours post infection with a peak of (figure ) . a similar observation of delayed onset of apoptosis was found in influenza h n and h n infected alveolar epithelial cells. besides, cdna array data of ex vivo infected human lung showed that both influenza h n and h n virus induced trail expression compared with mock-infected tissue (approximately folds) at hours post infection, but influenza h n virus infected lung induced significantly more trail ( folds compared to mock infected cells), albeit with a limited viral replication ( figure ). influenza h n virus infected lung also elicited more tnf-alpha and fasr transcription than either h n or h n . these observations can account for the greater apoptotic response in influenza h n virus infected lung. as little impact on the expression of intrinsic pathway components was observed, it seems that the apoptotic response to influenza virus infection in lung was mainly through the extrinsic pathways. no significant changes in the expression of anti-apoptotic protein gene was found, except for a moderate induction of birc by influenza h n virus, which may act to modulate the apoptotic response. the delayed onset of apoptosis by hpai h n and low pathogenic avian influenza h n virus infected respiratory epithelial cells may be a mechanism for the influenza viruses to have more prolonged replication within the human respiratory tract, and this may contribute to the pathogenesis of human disease. hemagglutination (ha) assay % crbc suspension was treated by mu a , -specific sialidase at °c for minutes. complete elimination of a , -receptor on sialidase-treated crbcs was confirmed by receptor staining and flow cytometry. ha assay of live viruses with % crbc or % sialidase-treated crbc were performed in bsl- facility. synthetic ¢sln-paa-biotin(pa ), ¢sln-paa-biotin(pa ), ¢sln-ln-paa-biotin(pa ) was provided by the scripps research institute (tsri). as described elsewhere with some modifications, generally, serial dilutions of sialyglycopolymers were coated in -well-flat-bottom polystryrene plates, and hau live virus ⁄ well were added. alternatively, the plates were precoated with lg ⁄ ml sialyglycopolymers, and then , , , , hau live virus ⁄ well influenza viruses were added. rabbit antisera against a ⁄ ah ⁄ ⁄ diluted in pbs containing % bsa was added into the wells. bound antibody was detected by use of hrp-conjugated anti-rabbit igg antibody and tetramethylbenzidine substrate solution. each sample was determined in duplicates and the absorbance read at nm. a total of h n virus strains were obtained from to . the name and passage history of influenza viruses used in the study are listed in table . as the same sequences of eight rna segments were detected in a ⁄ js ⁄ ⁄ and a ⁄ js ⁄ ⁄ , only a ⁄ js ⁄ ⁄ was tested here. three amantadine-resistant variants with m mutation of screening of receptor-binding preference by ha assay representative results from three sets of independent experiments are shown in table . complete ha with sialidasetreated crbcs, which were only with a , -receptors, was detected in human influenza virus (a ⁄ brisbane ⁄ ⁄ , h n ) and two human h n virus strains, a ⁄ gd ⁄ ⁄ and a ⁄ gx ⁄ ⁄ . high binding of a , oligosaccharides to h n viruses was detected ( figure a -c). and enhanced a , -binding preference was also detected in a ⁄ gd ⁄ ⁄ and a ⁄ gx ⁄ ⁄ . the a , -binding was dose dependent for sialyglycopolymers and virus titer. notably, as compared with a ⁄ gd ⁄ ⁄ of both short-and long-a , recognition, a ⁄ gx ⁄ ⁄ prefers to bind to long-a , six oligosaccharides at low viral titer ( figure b,c) . however, both of them showed strong affinity to short-and long-a , oligosaccharides at high viral loads ( figure d ). sialoside-, galactoside-, mannoside-and sulfo-os-binding are the four types of carbohydrate-binding properties of influenza virus. binding of influenza virus to the a , -or a , -linked sialylated glycans on cell surface is important for host range restriction, and the preference to a , of h n virus limited its efficient infection in human. here, dual receptor-binding preferences were detected in a ⁄ gd ⁄ ⁄ and a ⁄ gx ⁄ ⁄ , which are of clade ae ae . although there is no direct evidence supporting the occurrence of human-to-human transmission in these infection events or the association between viral virulence and receptor-binding switching, viral systemic disseminations are found in the both fatal cases (data not shown). furthermore, with the introduction of clade ae ae into the adjacent countries of china, the finding of h n virus with - binding in human should be of concern. though h n virus with human-type receptor-binding was isolated from one patient treated by oseltamivir and those viruses were with ha and ⁄ or na substitutions, whether the substitutions responsible for receptor specificity switching is pre-existed or selected in human host remains unknown. our finding that three mutant viruses bearing m mutations of a s, a t, and s n cloned from one isolate a ⁄ hb ⁄ ⁄ suggested it is likely that the resistant viruses emerged in the host environment. no variation was found in their ha and na sequence, and all of them show high affinity to a - -binding. our data suggest that the binding-specificity was not affected by the mutations on viral envelope protein m . with the adaptation from wild aquatic birds to domestic poultry or even in human host environment, influenza virus may possess broader carbohydrate-binding spectrum or topology conformation. , we demonstrated differential a , -binding property of two human h n viruses, a ⁄ gd ⁄ ⁄ and a ⁄ gx ⁄ ⁄ . though minor effect of short-a , -binding was detected in viruses a ⁄ gx ⁄ ⁄ at low virus titer, both were of high affinity to long-a , glycans, even at the low titer which are rich on apical side of human upper respiratory epithelia. notably, no evident binding preference switching was detected in the viruses isolated from the sporadic human infection cases at the early of in china (table ) . however, higher affinity to the long-a , glycans was observed in bj ⁄ ⁄ , gz ⁄ ⁄ , and xj ⁄ ⁄ (data not shown). the discrepancy from the findings obtained by sialidase-treated crbc maybe associated with a limited abundance of n-linked a - with long branches on crbc, as demonstrated in a recent study. therefore, glycan dose-dependent binding assay is valuable and should be applied in flu surveillance. the underlying cause of the tendency is unknown, and further research on receptor-binding specificity of h n viruses is required. influenza a viruses of migrating wild aquatic birds in north america towards improved influenza a virus surveillance in migrating birds european union council directive ⁄ ⁄ eec the neighbor-joining method: a new method for reconstructing phylogenetic trees confidence limits on phylogenies: an approach using the bootstrap prospects for inferring very large phylogenies by using the neighbor-joining method mega : molecular evolutionary genetics analysis (mega) software version . the influenza virus resource at the national center for biotechnology information characterization of low-pathogenic h subtype influenza viruses from eurasia: implications for the origin of highly pathogenic h n viruses h n virus outbreak in migratory waterfowl a ⁄ h and a ⁄ h influenza viruses: different lines of one precursor evolution and ecology of influenza a viruses evolutionary processes in influenza viruses: divergence, rapid evolution, and stasis antigenic and genetic conservation of h influenza virus in wild ducks biologic characterization of chicken-derived h n low pathogenic avian influenza viruses in chickens and ducks genetic and pathogenic characterization of h n avian influenza viruses isolated in taiwan between and experimental selection of virus derivatives with variations in virulence from a single low-pathogenicity h n avian influenza virus field isolate evolution and ecology of influenza a viruses is china an influenza epicenter genesis of a highly pathogenic and potentially pandemic h n influenza virus in eastern asia evolution and molecular epidemiology of h n influenza a viruses from quail in southern china establishment of influenza a virus (h n ) in minor poultry species in southern china h n influenza viruses: outbreaks and biological properties seroprevalance and identification of influenza a virus infection from migratory wild waterfowl in china avian flu: h n virus outbreak in migratory waterfowl migration of waterfowl in the east asian flyway and spatial relationship to hpai h n outbreaks avian influenza monitoring in migrating birds in taiwan during establishment of an h n influenza virus lineage in domestic ducks in southern china evolution and molecular epidemiology of h n influenza a viruses from quail in southern china the genesis and evolution of h n influenza viruses in poultry from southern china human infection with influenza h n human infection with an avian h n influenza a virus in hong kong in antigenic and genetic characterization of h n swine influenza in china cocirculation of avian h n and contemporary ''human'' h n influenza a viruses in pigs in southeastern china: potential for genetic reassortment? h n influenza a viruses from poultry in asia have human virus-like receptor specificity characterization of h subtype influenza viruses from the ducks of southern china: a candidate for the next influenza pandemic in humans? bioedit: a user-friendly biological sequence alignment editor and analysis program for window ⁄ ⁄ nt genetic algorithm approaches for the phylogenetic analysis of large biological sequence datasets under the maximum likelihood criterion phylogenetic analysis using parsimony (and other methods) . beta a novel genotype h n influenza virus possessing human h n internal genomes has been circulating in poultry in eastern china since characterization of h n influenza viruses isolated from vaccinated flocks in an integrated broiler chicken operation in eastern china during a year period characterization of avian h n influenza viruses from united arab emirates phylogenetic analysis of influenza a viruses of h haemagglutinin subtype h n subtype influenza a viruses in poultry in pakistan are closely related to the h n viruses responsible for human infection in hong kong diversified reassortants h n avian influenza viruses in chicken flocks in northern and eastern china genotypic evolution and antigenic drift of h n influenza viruses in china from the nucleoprotein as a possible major factor in determining host specificity of influenza h n viruses pigs as the ''mixing vessel'' for the creation of new pandemic influenza a viruses origins and evolutionary genomics of the swine-origin h n influenza a epidemic pandemic (h n ) outbreak on pig farm reassortment of pandemic h n ⁄ influenza a virus in swine from where did the 'swine-origin' influenza a virus (h n ) emerge? substitution of lysine at position in pb protein does not change virulence of the pandemic h n virus in mice evolution and ecology of influenza a viruses the origins of pandemic influenza -lessons from the virus characterization of the influenza virus polymerase genes origins and evolutionary genomics of the swine-origin h n influenza a epidemic emergence of a novel swine-origin influenza a (h n ) virus in humans antigenic and genetic characteristics of swine-origin a(h n ) influenza viruses circulating in humans genetic reassortment of avian, swine, and human influenza a viruses in american pigs detection of two antigenic subpopulations of a(h n ) influenza viruses from pigs: antigenic drift or interspecies transmission genetic relatedness of hemagglutinins of the h subtype of influenza a viruses isolated from swine and birds cases of swine influenza in humans: a review of the literature triple-reassortant swine influenza a (h ) in humans in the united states reassortment of pandemic h n ⁄ influenza a virus in swine ferrets as a transmission model for influenza: sequence changes in ha of type a (h n ) virus the ferret: an animal model to study influenza virus human and avian influenza viruses target different cells in the lower respiratory tract of humans and other mammals medical management of influenza infection incidence of adamantane resistance among influenza a (h n ) viruses isolated worldwide from to : a cause for concern surveillance of resistance to adamantanes among influenza a(h n ) and a(h n ) viruses isolated worldwide peramivir emergency use authorization peramivir and its use in h n influenza cs- , a prodrug of the new neuraminidase inhibitor r- , shows long-acting antiinfluenza virus activity detection of influenza viruses resistant to neuraminidase inhibitors in global surveillance during the first years of their use surveillance of influenza isolates for susceptibility to neuraminidase inhibitors during the - influenza seasons surveillance for neuraminidase inhibitor resistance among human influenza a and b viruses circulating worldwide from oseltamivir-resistant influenza viruses a (h n ), norway, - influenza activity -united states and worldwide, - season emergence of resistance to oseltamivir among influenza a(h n ) viruses in europe oseltamivir-resistant influenza virus a (h n ), europe, - season widespread oseltamivir resistance in influenza a viruses (h n ), south africa and composition of the - influenza vaccine emergence of h y oseltamivir-resistant a(h n ) influenza viruses in japan during the - season pyrosequencing as a tool to detect molecular markers of resistance to neuraminidase inhibitors in seasonal influenza a viruses neuraminidase sequence analysis and susceptibilities of influenza virus clinical isolates to zanamivir and oseltamivir host cell selection of influenza neuraminidase variants: implications for drug resistance monitoring in a(h n ) viruses neuraminidase receptor binding variants of human influenza a(h n ) viruses due to substitution of aspartic acid in the catalytic site -role in virus attachment? neuraminidase inhibitor susceptibility testing in human influenza viruses: a laboratory surveillance perspective update: drug susceptibility of swine-origin influenza a (h n ) viruses comprehensive assessment of pandemic influenza a (h n ) virus drug susceptibility in vitro detection of molecular markers of drug resistance in pandemic influenza a (h n ) viruses by pyrosequencing pandemic (h n ) and oseltamivir resistance in hematology/oncology patients fluview: a weekly influenza surveillance report prepared by the influenza division development of a sensitive chemiluminescent neuraminidase assay for the determination of influenza virus susceptibility to zanamivir evaluation of neuraminidase enzyme assays using different substrates to measure susceptibility of influenza virus clinical isolates to neuraminidase inhibitors: report of the neuraminidase inhibitor susceptibility network surveillance for neuraminidase inhibitor resistance among human influenza a and b viruses circulating worldwide from different neuraminidase inhibitor susceptibilities of human h n , h n , and h n influenza viruses isolated in germany from oseltamivir-and amantadine-resistant influenza viruses a (h n ) infections with oseltamivirresistant influenza a (h n ) virus in the united states isolation of oseltamivirresistant influenza a ⁄ h n virus of different origins in yokohama city, japan, during the - influenza season a two-year survey of the oseltamivir-resistant influenza a(h n ) virus in yamagata, japan and clinical effectiveness of oseltamivir and zanamivir oseltamivir-resistant influenza a pandemic (h n ) virus detection of an oseltamivir-resistant pandemic influenza a ⁄ h n virus in hong kong a novel small-molecule inhibitor of the avian influenza h n virus determined through computational screening against the neuraminidase aurintricarboxylic acid is a potent inhibitor of influenza a and b virus neuraminidases oseltamivir-resistant influenza a viruses are transmitted efficiently among guinea pigs by direct contact but not by aerosol oseltamivir is adequately absorbed following nasogastric administration to adult patients with severe h n influenza prevention and control of influenza influenza-associated hospitalizations in the united states mortality associated with influenza and respiratory syncytial virus in the united states severe respiratory disease concurrent with the circulation of h n influenza staphlococcus aureus pneumonia studies on influenza in the pandemic of - . ii. pulmonary complications of influenza bacterial pneumonia during the hong kong influenza epidemic of - streptococcus pneumonia diagnostic value of microscopic examination of gram-stained sputum and sputum cultures in patients with bacteremic pneumococcal pneumonia pneumonitis-associated hyperprocalcitoninemia clinical review : procalcitonin and the calcitonin gene family of peptides in inflammation, infection, and sepsis: a journey from calcitonin back to its precursors procalcitonin in sepsis and systemic inflammation: a harmful biomarker and a therapeutic target procalcitonin in children with suspected novel influenza a (h n ) infection in vitro and in vivo calcitonin i gene expression in parenchymal cells: a novel product of human adipose tissue serum procalcitonin and c-reactive protein levels as markers of bacterial infection: a systematic review and meta-analysis procalcitonin as a diagnostic test for sepsis in critically ill adults and after surgery or trauma: a systematic review and meta-analysis respiratory syncytial virus infection in elderly and high-risk adults procalcitonin assay in systemic inflammation, infection, and sepsis: clinical utility and limitations simultaneous detection of chlamydophila pneumoniae and mycoplasma pneumoniae by use of molecular beacons in a duplex real-time pcr years influenza therapy with antivirals (zanamivir and oseltamivir), nd world summit of antivirals the art of viewing and influenza -its importance for diagnosis, rd european influenza conference emergence of a novel swine origin influenza a (h n ) virus in humans origins and evolutionary genomics of the swine-origin h n influenza a epidemic molecular detection of a novel human influenza (h n ) of pandemic potential by conventional and real-time quantitative rt-pcr assays pandemic influenza a(h n )v: human to pig transmission in norway? an investigation into human pandemic influenza virus (h n ) on an alberta swine farm pandemic (h n ) infection in swine herds implications of the emergence of a novel h influenza virus emergence of a novel swine-origin influenza a virus (s-oiv) h n virus in humans rapid detection of reassortment of pandemic h n ⁄ influenza virus rapid diagnosis of a coronavirus associated with severe acute respiratory syndrome (sars) universal primer set for the fulllength amplification of all influenza a viruses cocirculation of avian h n and contemporary ''human'' h n influenza a viruses in pigs in southeastern china: potential for genetic reassortment? hog in the limelight: swine flu's got new genes on reassortment of pandemic h n ⁄ influenza a virus in swine pediatric hospitalizations associated with pandemic influenza a (h n ) in argentina factors associated with death or hospitalization due to pandemic influenza a(h n ) infection in california mortality from pandemic a ⁄ h n influenza in england: public health surveillance study antigenic and genetic characteristics of swine-origin a(h n ) influenza viruses circulating in humans characterization of a newly emerged genetic cluster of h n and h n swine influenza virus in the united states experimental inoculation of pigs with pandemic h n virus and hi cross-reactivity with contemporary swine influenza virus antisera triple-reassortant swine influenza a (h ) in humans in the united states identification of human h n and human-swine reassortant h n and h n influenza a viruses among pigs in ontario genetic and pathobiologic characterization of pandemic h n influenza viruses from a naturally infected swine herd archive number pandemic (h n ) outbreak on pig farm reassortment of pandemic h n ⁄ influenza a virus in swine a simple method for estimating percent endpoints occurrence of haemagglutinin mutation d g in pandemic influenza a(h n ) infected patients in the west of scotland rrt-pcr) protocol for detection and characterization of swine influenza (version diagnostic hybrids, inc. readycells respiratory training r-mixÔ&d Ô dfa respiratory virus screening & id kit handbook centers for disease and control and prevention. influenza laboratory course comparison study of a real-time reverse transcription polymerase chain reaction assay with an enzyme immunoassay and shell vial culture for influenza a and b virus detection in adult patients comparison of a commercial qualitative real-time rt-pcr kit with direct immunofluorescence assay (dfa) and cell culture for detection of influenza a and b in children prospective comparison of r-mix shell vial system with direct antigen tests and conventional cell culture for respiratory virus detection optimized detection of respiratory viruses in nasopharyngeal secretions evaluation of r-mix freshcells in shell vials for detection of respiratory viruses time lines of infection and disease in human influenza: a review of volunteer challenge studies comparative epidemiology of pandemic and seasonal influenza a in households viral shedding and clinical illness in naturally acquired influenza virus infections population modeling of influenza a/h n virus kinetics and symptom dynamics sensitivity of influenza rapid diagnostic tests to h n and pandemic h n viruses clinical evaluation of an immunochromatography test kit, capilia flua,b, for rapid diagnosis of influenza time to positive reaction of influenza rapid diagnosis kit and its clinical significance the speed and reliability of the antigen detection kit capilia flu a, b when used in a clinical setting options for the control of influenza vi role of rapid immunochromatographic antigen testing in diagnosis of influenza a virus h n infection poor clinical sensitivity of rapid antigen test for influenza a pandemic (h n ) virus evaluation of new rapid antigen test for the detection of pandemic influenza a ⁄ h n virus application of real-time cell electronic sensing (rt-ces) technology to cell-based assays world health organization. pandemic (h n ) role of the laboratory in diagnosis of influenza during seasonal epidemics and potential pandemics rapid detection and identification of respiratory viruses using a dual priming oligonucleotide systembased multiplex pcr assay world health organization. influenza world health organization. cdc protocol of realtime rtpcr for influenza a (h n ) development of a reverse transcription-loop-mediated isothermal amplification assay for detection of pandemic (h n ) virus as a novel molecular method for diagnosis of pandemic influenza in resource-limited settings one-step real-time rt-pcr for pandemic influenza a virus (h n ) matrix gene detection in swine samples detection of pandemic influenza a ⁄ h n ⁄ virus by real-time reverse transcription polymerase chain reaction detection of influenza a(h n )v virus by real-time rt-pcr development of a real-time rt-pcr for the detection of swine-lineage influenza a (h n ) virus infections evaluation of multiple test methods for the detection of the novel influenza a (h n ) during the new york city outbreak design and clinical application of a molecular method for detection and typing of the influenza a ⁄ h n pdm virus confirmation of the first hong kong case of human infection by novel swine origin influenza a (h n ) virus diagnosed using ultrarapid, real-time reverse transcriptase pcr evaluation of four real-time pcr assays for detection of influenza a(h n )v viruses diagnostic assay recommended by the world health organization for swine origin influenza a (h n ) virus cross-reacts with h n influenza virus increasing immunization coverage the cost-effectiveness of influenza vaccination for people aged to years: an international model national seasonal influenza vaccination survey in europe seasonal influenza and vaccination coverage influenza vaccination coverage rates in five european countries during season ⁄ and trends over six consecutive seasons influenza in the elderly -a mini-review cost of vaccine administration among pediatric practices cost of universal influenza vaccination of children in pediatric practices surveillance report: respiratory infections strategies for mitigating an influenza pandemic methods for monitoring influenza surveillance data approaches to syndromic surveillance when data consist of small regional counts rrt-pcr) protocol for detection and characterization of swine influenza (version influenza virus strains circulating in mongolia in - swine influenza who ( ) influenza a(h n ) world now at the start of influenza pandemic general statement following the ninth meeting of the emergency committee who ( ) influenza updates us dept of defense global emerging infections surveillance è me recensement general de la population et l'habitat (rgph ), ministè re de l'economie des finances et de la planification ministry of health djibouti a survey of human cases of h n avian influenza report by who before international health regulation (ihr) electronic public health surveillance in developing settings statistical analyses in disease surveillance systems potential for a global dynamic of influenza a (h n ) infectious disease informatics: syndromic surveillance for public health and biodefense visualization techniques and graphical user interfaces in syndromic surveillance systems statistical inference for infectious diseases. risk-specific household and community transmission parameters evaluation of seasonal influenza vaccination effectiveness based on antibody efficacy among the institutionalized elderly in japan australian influenza surveillance summary report. canberra: australian government department of health and ageing australia's winter with the pandemic influenza a (h n ) virus seroprevalence of pandemic influenza a(h n ) virus in australian blood donors pandemic vaccination survey: summary results. cat. no. phe concepts and procedures for laboratory-based influenza surveillance. who collaborating centres for reference and research on influenza influenza a(h n ) seroconversion rates and risk factors among distinct adult cohorts in singapore ecdc. forward look risk assessment: likely scenarios for influenza in and the ⁄ influenza season in europe and the consequent work priorities. stockholm: european centre for disease prevention and control epidemiology of influenza -summary of influenza workshop iv sampling of populations: methods and applications comparison of influenza serological techniques by international collaborative study eliminating bias in the estimation of the geometric mean of hi titres reply to ''nauta jjp, eliminating bias in the estimation of the geometric mean of hi titers novel influenza a virus infections. case definition institut national de la statistique et des é tudes é conomiques. taille des mé nages dans l'union europé enne estimation de la population au er janvier par ré gion, dé partement, sexe et â ge sero-immunity and serologic response to pandemic influenza a (h n ) virus in hong kong pandemic influenza a(h n ) virus in scotland: geographically variable immunity in spring , following the winter outbreak high prevalence of antibodies to the pandemic influenza a(h n ) virus in the norwegian population following a major epidemic and a large vaccination campaign in autumn incidence of pandemic influenza a h n infection in england: a cross-sectional serological study prevalence of seroprotection against the pandemic (h n ) virus after the pandemic antibodies in residents of new south wales, australia, after the first pandemic wave in the southern hemisphere winter older age and a reduced likelihood of h n virus infection pre-existing antibody response against pandemic influenza h n viruses in taiwanese population cross-reactive antibody responses to the pandemic h n influenza virus seasonal influenza vaccine and increased risk of pandemic a ⁄ h n -related illness: first detection of the association in british columbia association between the - seasonal influenza vaccine and pandemic h n illness during spring-summer : four observational studies from canada does seasonal influenza vaccination increase the risk of illness with the a ⁄ h n pandemic virus seasonal h n influenza virus infection is associated with elevated pre-exposure antibody titers to the serum cross-reactive antibody response to a novel influenza a (h n ) virus after vaccination with seasonal influenza vaccine world now at the start of influenza pandemic rki working group pandemic. the first wave of pandemic influenza (h n ) in germany: from initiation to acceleration department of health and ageing. australian influenza surveillance canadian surveillance studies help to understand h n patterns influenza pandé mica a un añ o de la primera ola. ¿qué podemos decir ahora? revista chilena de infectología pandemic (h n ) briefing note options for the control of influenza vii managing and reducing uncertainty in an emerging influenza pandemic the severity of pandemic h n influenza in the united states assessing the severity of the novel influenza a ⁄ h n pandemic tecumseh study of illness. xiii. influenza infection and disease, - the infection attack rate and severity of pandemic influenza (h n ) in hong kong school closure and mitigation of pandemic (h n ) , hong kong comparative epidemiology of pandemic and seasonal influenza a in households incidence of pandemic influenza a h n infection in england: a cross-sectional serological study mortality from pandemic a ⁄ h n influenza in england: public health surveillance study monthly summary tables of influenza virus isolation different epidemic curves for severe acute respiratory syndrome reveal similar impacts of control measures estimating in real time the efficacy of measures to control emerging communicable diseases the effective reproduction number of pandemic influenza in hong kong: prospective estimation multiple imputation: a primer comparative epidemiology of pandemic and seasonal influenza a in households strategies for containing an emerging influenza pandemic in southeast asia estimation of the serial interval of influenza school closure and mitigation of pandemic (h n ) , hong kong estimating the reproduction number of the novel influenza a virus (h n ) in a southern hemisphere setting: preliminary estimate in new zealand early transmission characteristics of influenza a(h n )v in australia: victorian state methods for monitoring influenza surveillance data comparative estimation of the reproduction number for pandemic influenza from daily case notification data how to maintain surveillance for novel influenza a h n when there are too many cases to count a computational framework for influenza antigenic cartography mapping the antigenic and genetic evolution of influenza virus proc of kdd cup and workshop matrix factorization techniques for recommender systems exact matrix completion via convex optimization a singular value thresholding algorithm for matrix completion matrix completion from a few entries matrices with prescribed entries and eigenvalues combining predictions for accurate recommender systems the bellkor solution to the netflix grand. prize the pragmatic theory solution to the netix grand prize feature-weighted linear stacking technical report. of health and ageing (australia). the australian health management plan for pandemic influenza influenza pandemic contingency plan, version . world health organisation. pandemic influenza preparedness and response prophylaxis or treatment? optimal use of an antiviral stockpile during an influenza pandemic the response to novel influenza a (h n ) epidemic in taiwan and analysis of the initial confirmed cases mitigation strategies for pandemic influenza in the united states strategies for mitigating an influenza pandemic containing pandemic influenza at the source efficient simulation of the spatial transmission dynamics of influenza world health organization. mathematical modelling of the pandemic h n a mathematical model for the global spread of influenza pandemic potential of a strain of influenza a (h n ): early findings effectiveness of the - influenza vaccine among children months to years of age, with vs doses cdc estimates of h n influenza cases, hospitalizations and deaths in the united states accessed entry screening for severe acute respiratory syndrome (sars) or influenza: policy evaluation pandemic of influenza - america's forgotten pandemic. the influenza of influenza: a survey of the last years in the light of modern work on the virus of epidemic influenza understanding mortality in the - influenza pandemic in england and wales genomic analysis of increased host immune and cell death responses induced by influenza virus the age pattern of mortality in the - influenza pandemic: an attempted explanation based on data for england and wales protective immunity and susceptibility to infectious diseases: lessons from the influenza pandemic deaths from bacterial pneumonia during - influenza pandemic understanding influenza transmission, immunity and pandemic threats a biological model for influenza transmission: pandemic planning implications of asymptomatic infection and immunity prior immunity helps to explain wave-like behaviour of pandemic influenza in - influenza: accounting for prior immunity - influenza pandemic mortality in england and wales. colchester, essex: uk data archive [distributor] cross-reactive antibody responses to the pandemic h n influenza virus australia's winter with the pandemic influenza a (h n ) virus model predictions and evaluation of possible control strategies for the a ⁄ h n v influenza pandemic in italy the role of population heterogeneity and human mobility in the spread of pandemic influenza age-prioritized use of antivirals during an influenza pandemic mitigation measures for pandemic influenza in italy: an individual based model considering different scenarios strategies for containing an emerging influenza pandemic in southeast asia modeling targeted layered containment of an influenza pandemic in the united states reducing the impact of the next influenza pandemic using household-based public health interventions mitigation strategies for pandemic influenza in the united states effective, robust design of community mitigation for pandemic influenza: a sytematic examination of proposed us guidance containing pandemic influenza at the source strategies for mitigating an influenza pandemic new influenza a (h n ) virus: global epidemiological situation velluci l. enhanced epidemiological surveillance of influenza a(h n )v in italy changes in reporting requirements for pandemic (h n ) virus infection use of the oral neuraminidase inhibitor oseltamivir in experimental human influenza guidance document: pandemic influenza preparedness and response situation updates -pandemic (h n ) pandemic potential of a strain of influenza a (h n ): early findings estimating the impact of school closure on influenza transmission from sentinel data preexisting immunity to pandemic (h n ) understanding the dynamics of seasonal influenza in italy: an analysis of disease incidence and population susceptibility what is the optimal therapy for patients with h n influenza meta-analysis: convalescent blood products for spanish influenza pneumonia: a future h n treatment? treatment with convalescent plasma for influenza a (h n ) infection prophylactic and therapeutic efficacy of human monoclonal antibodies against h n influenza logistical feasibility and potential benefits of a population-wide passive-immunotherapy program during an influenza pandemic strategies for pandemic and seasonal influenza vaccination of schoolchildren in the united states mitigation strategies for pandemic influenza in the united states pandemic potential of a strain of influenza a (h n ): early findings transmission potential of the new influenza a(h n ) virus and its age-specificity in japan the transmissibility and control of pandemic influenza a (h n ) virus effect of clinical and virological parameters on the level of neutralizing antibody against pandemic influenza a virus h n world health organization. facts on blood transfusion hyperinduction of cyclooxygenase- -mediated proinflammatory cascade: a mechanism for the pathogenesis of avian influenza h n infection the role of influenza virus gene constellation and viral morphology on cytokine induction, pathogenesis, and viral virulence induction of proinflammatory cytokines in human macrophages by influenza a (h n ) viruses: a mechanism for the unusual severity of human disease? analysis of relative gene expression data using real-time quantitative pcr and the acetylsalicylic acid (asa) blocks influenza virus propagation via its nf-kappab-inhibiting activity cyclooxygenase plays a pivotal role in the resolution of acute lung injury role of -deoxy delta( , ) prostaglandin j and nrf pathways in protection against acute lung injury resolution of inflammation in murine autoimmune arthritis is disrupted by cyclooxygenase- inhibition and restored by prostaglandin e -mediated lipoxin a production inhibition of cox- aggravates neutrophil migration and pneumocyte apoptosis in surfactantdepleted rat lungs re-emergence of fatal human influenza a subtype h n disease apoptosis and pathogenesis of avian influenza a (h n ) virus in humans h n infection of the respiratory tract and beyond: a molecular pathology study molecular biology, and pathogenesis of avian influenza a (h n ) infection in humans passive immunity in prevention and treatment of infectious diseases prophylactic and therapeutic efficacy of human monoclonal antibodies against h n influenza neutralizing human monoclonal antibody against h n influenza ha selected from a fab-phage display library passive immunoprophylaxis and therapy with humanized monoclonal antibody specific for influenza a h hemagglutinin in mice generation, characterization and epitope mapping of two neutralizing and protective human recombinant antibodies against influenza a h n viruses igy: clues to the origins of modern antibodies chicken antibodies: a clinical chemistry perspective oral immunotherapy with yolk antibodies to prevent infections in humans and animals good effect of igy against pseudomonas aeruginosa infections in cystic fibrosis patients avian influenza vaccines: a practical review in relation to their application in the field with a focus on the asian experience vaccination: a tool for the control of avian influenza immunoglobulins from egg yolk: isolation and purification a simple method of estimating fifty per cent endpoints characterization of the reconstructed spanish influenza pandemic virus detection of antibody to avian influenza a (h n ) virus in human serum by using a combination of serologic assays avian influenza (h n ) viruses isolated from humans in asia in exhibit increased virulence in mammals heterosubtypic immunity to influenza a virus infection requires a properly diversified antibody repertoire early control of h n influenza virus replication by the type i interferon response in mice successful treatment of avian influenza with convalescent plasma chicken antibodies: taking advantage of evolution -a review oral administration of specific yolk antibodies (igy) may prevent pseudomonas aeruginosa infections in patients with cystic fibrosis: a phase i feasibility study avian flu: isolation of drug-resistant h n virus reduced sensitivity of influenza a (h n ) to oseltamivir enzymatic properties of the neuraminidase of seasonal h n influenza viruses provide insights for the emergence of natural resistance to oseltamivir surveillance for neuraminidase inhibitor resistance among human influenza a and b viruses circulating worldwide from a polyphenol rich plant extract, cystus , exerts anti influenza virus activity in cell culture without toxic side effects or the tendency to induce viral resistance cystus , a polyphenol-rich plant extract, exerts anti-influenza virus activity in mice cistus incanus (cystus ) for treating patients with infection of the upper respiratory tract. a prospective, randomised, placebocontrolled clinical study in vitro and in vivo assay systems for study of influenza virus inhibitors new low-viscosity overlay medium for viral plaque assays antibacterial and antifungal activities of cistus incanus and c. monspeliensis leaf extracts flavan- -ols and proanthocyanidins from cistus incanus inhibition of the infectivity of influenza virus by tea polyphenols attenuation of inducible respiratory immune responses by oseltamivir treatment in mice infected with influenza a virus anti-inflammatory activity of macrolides: a new therapeutic potential? macrolide antibiotics as immunomodulatory medications: proposed mechanisms of action proteases essential for human influenza virus entry into cells and their inhibitors as potential therapeutic agents modified pulmonary surfactant is a potent adjuvant that stimulates the mucosal iga production in response to the influenza virus antigen boost of mucosal sectretory immunoglobulin a response by clarithromycin in paediatric influenza intranasal interleukin- is a powerful adjuvant for protective mucosal immunity immunological effects of the orally administered neuraminidase inhibitor oseltamivir in influenza virus-infected and uninfected mice clarithromycin in the treatment of rsv bronchitis: a double-blind, randomized placebo-controlled trial bird flu''), inflammation and anti-inflammatory ⁄ analgesic drugs clinical effects of low-dose long-term erythromycin chemotherapy on diffuse panbronchiolitis proteolytic activation of influenza viruses by serine proteases tmprss and hat from human airway epithelium proteolytic activation of the influenza virus hemagglutinin protease-activated receptors: new concepts in regulation of g protein-coupled receptor signaling and trafficking protective role for protease-activated receptor- against influenza virus pathogenesis via an ifn-gamma-dependent pathway agonists of proteinaseactivated receptor- enhance ifn-gamma-inducible effects on human monocytes: role in influenza a infection plasmacytoid dendritic cells migrate in afferent skin lymph annexin ii incorporated into influenza virus particles supports virus replication by converting plasminogen into plasmin plasminogen promotes influenza a virus replication through an annexin ii-dependent pathway in absence of neuraminidase costimulatory receptors in a teleost fish: typical cd , elusive ctla trypsin increases pseudorabies virus production through activation of the erk signalling pathway characterization of hla-g , -g , -g , and -g isoforms transfected in a human melanoma cell line immunosuppressive hla-g molecule is upregulated in alveolar epithelial cells after influenza a virus infection influenza virus propagation is impaired by inhibition of the raf ⁄ mek ⁄ erk signalling cascade influenza viruses and the nf-kappab signaling pathway -towards a novel concept of antiviral therapy the immunotolerance role of hla-g hla-g co-expression boosts the hla class i-mediated nk lysis inhibition hla-g inhibits the allogeneic proliferative response hla-g-mediated inhibition of antigen-specific cytotoxic t lymphocytes the world health organization. h n influenza vaccine task force pandemic influenza: a potential role for statins in treatment and prophylaxis commentary: from scarcity to abundance: pandemic vaccines and other agents for ''have not'' countries new technologies for meeting the global demand for pandemic vaccines confronting the next influenza pandemic with inexpensive generic agents: can it be done? was bacterial pneumonia the predominant cause of death in the - influenza pandemic? meeting the challenge of influenza pandemic preparedness in developing countries confronting the next influenza pandemic with antiinflammatory and immunomodulatory agents: why they are needed and how they might work molecular and cellular aspects of sepsis-induced immunosuppression immune homeostasis in the respiratory tract and its impact on heterologous infection identification of oxidative stress and toll-like receptor signaling as a key pathway of acute lung injury effector t cells control lung inflammation during acute influenza virus infection by producing il- a detrimental effect of interleukin- on protective pulmonary humoral immunity during primary influenza a virus infection inhibition of influenza a virus replication by resveratrol increased survival after gemfibrozil treatment of severe mouse influenza tnf ⁄ inos-producing dendritic cells are the necessary evil of lethal influenza virus infection peroxisome proliferator-activated receptor and amp-activated protein kinase agonists protect against lethal influenza virus challenge in mice acetylsalicylic acid (asa) blocks influenza virus propagation via its nf-kappab-inhibiting activity new low-viscosity overlay medium for viral plaque assays cyproquant-pcr: a real time rt-pcr technique for profiling human cytokines, based on external rna standards, readily automatable for clinical use role of hypercytokinemia in nf-kap-pab p deficient mice after h n influenza a virus infection developing new antiviral agents for influenza treatment: what does the future hold? influenza viruses and the nf-kappab signaling pathway -towards a novel concept of antiviral therapy rna viruses and the mitogenic raf ⁄ mek ⁄ erk signal transduction cascade world health organization writing group. non-pharmaceutical interventions for pandemic influenza, international measures effects of school closures, winter influenza season, hong kong entry screening to delay local transmission of pandemic influenza a (h n ) simple physical interventions such as hand washing and wearing masks can reduce spread of respiratory viruses hand hygiene and virus transmission demographic and attitudinal determinants of protective behaviours during a pandemic: a review perceptions related to human avian influenza and their associations with anticipated psychological and behavioral responses at the onset of outbreak in the hong kong chinese general population perceptions about status and modes of h n transmission and associations with immediate behavioral responses in the hong kong general population longitudinal assessment of community psychobehavioral responses during and after the outbreak of severe acute respiratory syndrome in hong kong public perceptions, anxiety, and behaviour change in relation to the swine flu outbreak: cross sectional telephone survey community psychological and behavioral responses through the first wave of the influenza a(h n ) pandemic in hong kong main tables of the population census. hong kong: government of the statistical analysis with missing data the impact of community psychological responses on outbreak control for severe acute respiratory syndrome in hong kong economic impact of sars: the case of hong kong sars-related perceptions in hong kong group members: stream -ilaria oie -world organisation for animal health, france; malik peiris us department of health and human services, usa; masato tashiro, national institute of infectious diseases, japan; marie-paule kieny , david wood . stream -tawee chotpitayasunondh world influenza centre at national institute for medical research philippe veltsos , cathy roth , gregory härtl options for the control of influenza vii who public health research agenda for influenza outbreak communication best practices for communicating with the public during an outbreak, doc who ⁄ cds ⁄ . . geneva: world health organization who outbreak communications guidelines, geneva: world health organization characterization of h subtype influenza viruses from the ducks of southern china: a candidate for the next influenza pandemic in humans? genetic conservation of hemagglutinin gene of h influenza virus in chicken population in mainland china continuing evolution of h influenza viruses in korean poultry evolution and molecular epidemiology of h n influenza a viruses from quail in southern china characterization of the pathogenicity of members of the newly established h n influenza virus lineages in asia sequence analysis of the hemagglutinin gene of h n korean avian influenza viruses and assessment of the pathogenic potential of isolate ms molecular characterization of h n influenza viruses: were they the donors of the ''internal'' genes of h n viruses in hong kong? h n influenza viruses possessing h n -like internal genomes continue to circulate in poultry in southeastern china role of infectious bronchitis live vaccine on pathogenicity of h n avian influenza virus manual of diagnostic tests and vaccines for terrestrial animals (mammals, birds and bees) an avian influenza virus of h subtype that is highly pathogenic for chickens, but lacks multiple basic amino acids at the haemagglutinin cleavage site human influenza virus hemagglutinin with high sensitivity to proteolytic activation insertion of a multibasic cleavage motif into the hemagglutinin of a low-pathogenic avian influenza h n virus induces a highly pathogenic phenotype acquisition of a polybasic hemagglutinin cleavage site by a low-pathogenic avian influenza virus is not sufficient for immediate transformation into a highly pathogenic strain pathology and virus distribution in chickens naturally infected with highly pathogenic avian influenza a virus (h n ) during the outbreak in the netherlands implication of the proprotein convertases furin, pc and pc in the cleavage of surface glycoproteins of hong kong, ebola and respiratory syncytial viruses: a comparative analysis with fluorogenic peptides substrate cleavage analysis of furin and related proprotein convertases. a comparative study cloning and expression of novel mosaic serine proteases with and without a transmembrane domain from human lung host envelope glycoprotein processing proteases are indispensable for entry into human cells by seasonal and highly pathogenic avian influenza viruses world health organization ⁄ oie ⁄ fao h n evolution working group. toward a unified nomenclature system for highly pathogenic avian influenza virus (h n ) novel type ii transmembrane serine proteases, mspl and tmprss , proteolytically activate membrane fusion activity of hemagglutinin of highly pathogenic avian influenza viruses and induce their multicycle replication is virulence of h n influenza viruses in chickens associated with loss of carbohydrate from the hemagglutinin? targeted infection of endothelial cells by avian influenza virus a ⁄ fpv ⁄ rostock ⁄ (h n ) in chicken embryos detection of circulating asian h n viruses by a newly established monoclonal antibody a novel influenza a virus mitochondrial protein that induces cell death influenza a virus pb -f protein contributes to viral pathogenesis in mice expression of the influenza a virus pb -f enhances the pathogenesis of viral and secondary bacterial pneumonia the influenza a virus pb -f protein targets the inner mitochondrial membrane via a predicted basic amphipathic helix that disrupts mitochondrial function influenza virus pb -f protein induces cell death through mitochondrial ant and vdac a single mutation in the pb -f of h n (hk ⁄ ) and influenza a viruses contributes to increased virulence the effects of influenza a virus pb -f protein on polymerase activity are strain specific and do not impact pathogenesis eight-plasmid system for rapid generation of influenza virus vaccines pb -f proteins from h n and century pandemic influenza viruses cause immunopathology pneumonia and respiratory failure from swine-origin influenza a (h n ) in mexico emergence of a novel swine-origin influenza a (h n ) virus in humans dating the emergence of pandemic influenza viruses in vitro and in vivo characterization of new swine-origin h n influenza viruses emergence of a novel swine-origin influenza a virus (s-oiv) h n virus in humans influenza: emergence and control systemic cytokine responses in patients with influenza-associated encephalopathy inflammatory cytokines in vascular dysfunction and vascular disease identification of trypsin i as a candidate for influenza a virus and sendai virus envelope glycoprotein processing protease in rat brain mechanisms of matrix metalloprotease- upregulation and tissue destruction in various organs in influenza a virus infection activation of influenza a viruses by trypsin treatment host envelope glycoprotein processing proteases are indispensable for entry into human cells by seasonal and highly pathogenic avian influenza viruses dystroglycan is selectively cleaved at the parenchymal basement membrane at sites of leukocyte extravasation influenza virus-cytokine-protease cycle in the pathogenesis of vascular hyperpermeability in severe influenza molecular pathogenesis of influenza a virus infection and virus-induced regulation of cytokine gene expression active nf-jb signaling is a prerequisite for influenza virus infection nf-jb and virus infection: who controls whom tnf-induced mitochondrial damage: a link between mitochondrial complex i activity and left ventricular dysfunction acute encephalopathy associated with influenza and other viral infections molecular structure and assembly of the tight junction identification of oxidative stress and toll-like receptor signaling as a key pathway of acute lung injury human influenza virus infection and apoptosis induction in human vascular endothelial cells fatal outcome of human influenza a (h n ) is associated with high viral load and hypercytokinemia h n infection of the respiratory tract and beyond: a molecular pathology study fatal avian influenza a (h n ) in a child presenting with diarrhea followed by coma influenza virus m protein mediates escrt-independent membrane scission the protein-protein interaction map of helicobacter pylori development of a real-time rt-pcr for the detection of swine-lineage influenza a (h n ) virus infections long-term storage and recovery of buccal cell dna from treated cards pandemic a(h n ) influenza virus detection by real time rt-pcr: is viral quantification useful? the effect of storage at different temperatures on the stability of hepatitis c virus rna in plasma samples impact of various handling and storage conditions on quantitative detection of hepatitis c virus rna blood storage at degrees c-factors involved in dna yield and quality effects of prolonged storage of whole plasma or isolated plasma dna on the results of circulating dna quantification assays pathogenesis and transmission of swine-origin a(h n ) influenza virus in ferrets viral tropism and the pathogenesis of influenza in the mammalian host influenza: pathogenesis and host defense cutting edge: stealth influenza virus replication precedes the initiation of adaptive immunity genetic and antiviral drug susceptibility profiles of pandemic a(h n )v influenza virus circulating in portugal observed association between the ha mutation d g in the pandemic influenza a(h n ) virus and severe clinical outcome world health organization. sequencing primers and protocol antiviral drug profile of seasonal influenza viruses circulating in portugal from predicting the antigenic structure of the pandemic (h n ) influenza virus hemagglutinin genomic signature and mutation trend analysis of pandemic (h n ) influenza a virus weekly update on oseltamivir resistance to influenza a (h n ) viruses pandemic a(h n ) influenza virus detection by real-time rt-pcr: is viral quantification useful? virulence associated substitution d g in hemagglutinin of pandemic influenza a(h n ) virus affects receptor binding the first wave of pandemic influenza (h n ) in germany: from initiation to acceleration new york city swine flu investigation team, et al. the severity of pandemic h n influenza in the united states from rhinovirus delayed the circulation of the pandemic influenza a(h n ) virus in france dynamics and impact of the a(h n ) epidemic in metropolitan france clinical aspects of pandemic influenza a(h n ) virus infection preliminary estimates of mortality and years of life lost associated with the a ⁄ h n pandemic in the us and comparison with past influenza seasons oseltamivir resistance in adult oncology and hematology patients infected with pandemic (h n ) virus household transmission of the pandemic a ⁄ h n influenza virus: elevated laboratoryconfirmed secondary attack nrates and evidence of assymptomatic infections time lines of infection and disease in human influenza: a review of volunteer challenge studies facemasks and hand hygiene to prevent influenza transmission in households comparative epidemiology of pandemic and seasonal influenza a in households viral shedding and clinical illness in naturally acquired influenza virus infections r: a language and environment for statistical computing the guinea pig as a transmission model for human influenza viruses in the control of epidemic and pandemic influenza - blocking interhost transmission of influenza virus by vaccination in the guinea pig model phenotypic properties resulting from directed gene segment reassortment between wild-type a ⁄ sydney ⁄ ⁄ influenza virus and the live attenuated vaccine strain emergence of a novel swine-origin influenza a (h n ) virus in humans pneumonia and respiratory failure from swine-origin influenza a (h n ) in mexico cumulative number of confirmed human cases of avian influenza a ⁄ (h n ) reported to who factors involved in the aerosol transmission of infection and control of ventilation in healthcare premises airborne transmission of disease in hospitals noninvasive positive-pressure ventilation: an experimental model to assess air and particle dispersion airflow and droplet spreading around oxygen masks: a simulation model for infection control research coughing and aerosols. images in clinical medicine antimicrobial products registered for use against influenza a virus on hard surfaces. office of pesticide programs u.s. environmental protection agency antimicrobials division the genesis of a pandemic influenza virus influenza in the elderly -a mini review control of influenza in the long term care facility: a review of established approaches and newer options a study of the impact of influenza on the functional status of frail older people influenza in long-term care facilities: preventable, detectable, treatable mortality associated with influenza and respiratory syncytial virus in the united states causes of death australia : leading causes of death australian government department of heath and ageing. pandemic (h n ) update bulletins for pandemic (h n ) update bulletins for world health organization. pandemic (h n ) -update factors associated with death or hospitalization due to pandemic influenza a (h n ) infection in california influenza a (h n ) antibodies in residents of new south wales, australia, after the first pandemic wave in the southern hemisphere winter qualification of the hemagglutination inhibition assay in support of pandemic influenza vaccine licensure managing outbreaks of viral respiratory infection in aged care facilities -challenges and difficulties during the first pandemic wave laboratory diagnosis of influenza virus infection antigenic and genetic characteristics of swine-origin a(h n ) influenza viruses circulating in humans incidence of pandemic influenza a h n infection in england: a cross-sectional serological study cross-reactive antibody responses to the pandemic h n influenza virus in vitro and in vivo characterization of new swine-origin h n influenza viruses cross-reacting antibodies against pandemic influenza a (h n ) virus in elderly australians rhinovirus outbreak in a long term care facility for elderly persons associated with unusually high mortality a rhinovirus outbreak among residents of a long term care facility lessons from a respiratory illness outbreak in an aged-care facility detection and isolation of pandemic (h n ) influenza virus infection among pediatric patients reporting diarrhea and influenza-like illness significance of seasonal influenza viruses in the stool of pediatric patients viral load in patients infected with pandemic h n influenza a virus haemagglutinin mutations responsible for the binding of h n influenza a viruses to human-type receptors biedermann e references world health organization writing group. nonpharmaceutical interventions for pandemic influenza, international measures avian influenza, including influenza a (h n ), in humans: who interim infection control guideline for health care facilities inactivation of influenza a viruses in the environment and modes of transmission: a critical review quantitative method for evaluating virucidal activity of biocides used on hard surfaces nonpharmaceutical interventions for pandemic influenza, international measures avian influenza, including influenza a (h n ), in humans: who interim infection control guideline for health care facilities inactivation of influenza a viruses in the environment and modes of transmission: a critical review distribution of airborne influenza virus and respiratory syncytial virus in an urgent care medical clinic characterisation of stability, cytotoxicity, and skin sensitisation and irritation for respirators with antiviral coating nonpharmaceutical interventions for pandemic influenza, international measures avian influenza, including influenza a (h n ), in humans: who interim infection control guideline for health care facilities c cf/ /infectioncontrol.pdf international organization for standardization. : biological evaluation of medical devices, part : tests for cytotoxicity: in vitro methods effects of antiviral drugs on viral detection in influenza patients and on the sequential infection to their family members. serial examination by quick diagnosis (capiria) and virus culture intrafamilial transmission of influenza a and b analysis of infectious diseases data stochastic models for analysis of household transmission data: examining human-made transmission experiments factors influencing the effectiveness of oseltamivir and amantadine for the treatment of influenza. a japanese study of the multi-center study of the ⁄ influenza season clinical evaluation of an immunochromatography test kit, capilia flua, b for rapid diagnosis of influenza usefulness of a self-blown nasal discharge specimen for use with immunochromatography based influenza rapid antigen test. options for control of influenza vii ; abstract book. options for the control of influenza vii strategies for containing an emerging influenza pandemic in southeast asia flute, a publicly available stochastic influenza epidemic simulation model the japanese experience with vaccinating schoolchildren against influenza mass vaccination of schoolchildren against influenza and its impact on the influenza-associated mortality rate among children in japan effect of vaccination of a school-age population upon the course of an a -hong kong influenza epidemic herd immunity in adults against influenza-related illnesses with use of the trivalent-live attenuated influenza vaccine (caiv-t) in children the effect of mass influenza immunization in children on the morbidity of the unvaccinated elderly effect of influenza vaccination of children on infection rates in hutterite communities: a randomized trial efficacy of live attenuated and inactivated influenza vaccines in schoolchildren and their unvaccinated contacts in novgorod, russia effectiveness of influenza vaccination of day care children in reducing influenza-related morbidity among household contacts effectiveness of schoolbased influenza vaccination strategies for pandemic and seasonal influenza vaccination of schoolchildren in the united states strategy for distribution of influenza vaccine to high-risk groups and children estimating the impact of childhood influenza vaccination programmes in england and wales population-wide benefits of routine vaccination of children against influenza prevention and control of seasonal influenza with vaccines: recommendations of the advisory committee on immunization practices (acip) protective efficacy of seasonal influenza vaccination against seasonal and pandemic influenza virus infection during in hong kong partial protection of seasonal trivalent inactivated vaccine against novel pandemic influenza a ⁄ h n : case-control study in mexico city association between the - seasonal influenza vaccine and pandemic h n illness during spring-summer : four observational studies from canada cross-reactive antibody responses to the pandemic h n influenza virus effectiveness of - trivalent influenza vaccine against pandemic influenza a (h n ) -united states seasonal influenza vaccine and protection against pandemic (h n ) -associated illness among us military personnel interim analysis of pandemic influenza (h n ) in australia: surveillance trends, age of infection and effectiveness of seasonal vaccination pandemic (h n ) risk for nurses after trivalent vaccination infection and death from influenza a h n virus in mexico: a retrospective analysis birth weight, infant growth, and childhood body mass index: hong kong's children of birth cohort comparative epidemiology of pandemic and seasonal influenza a in households facemasks and hand hygiene to prevent influenza transmission in households: a cluster randomized trial partial protection against challenge with the highly pathogenic h n influenza virus isolated in japan in chickens infected with the h n influenza virus prior h n influenza infection and susceptibility of cleveland family study participants during the h n pandemic of : an experiment of nature transmission of pandemic h n influenza virus and impact of prior exposure to seasonal strains or interferon treatment prior infection with an h n swine influenza virus partially protects pigs against a low pathogenic h n avian influenza virus protection against a european h n swine influenza virus in pigs previously infected with h n and ⁄ or h n subtypes infection of mice with a human influenza a ⁄ h n virus induces protective immunity against lethal infection with influenza a ⁄ h n virus evidence of a cross-protective immune response to influenza a in the cotton rat model heterosubtypic immunity to influenza a virus: where do we stand? safety and immunogenicity of as b adjuvanted split virion versus non-adjuvanted whole virion h n influenza vaccine in uk children aged months- years: open label, randomised, parallel group, multicentre study options for live attenuated influenza vaccines (laiv) in the control of epidemic and pandemic influenza - pilot studies on recombinant cold-adapted live type a and b influenza virus vaccines development of cold-adapted recombinant live, attenuated influenza vaccines in usa and ussr clinical and epidemiological evaluation of a live, cold-adapted influenza vaccine for - -year-olds revised requirements for influenza vaccine (live) global pandemic influenza action plan to increase vaccine supply characteristics of human influenza a ⁄ h n , a ⁄ h n and b viruses isolated characteristics of human influenza a ⁄ h n , a ⁄ h n and b viruses isolated characteristics of human influenza a ⁄ h n , a ⁄ h n and b viruses isolated characteristics of human influenza a ⁄ h n , a ⁄ h n and b viruses isolated dynamics of antigenic and genetic changes in the hemagglutinins of influenza a ⁄ h n viruses of three consecutive seasons molecular epidemiology of a ⁄ h n and a ⁄ h n influenza virus during a single epidemic season in the united states an mf -adjuvanted inactivated influenza vaccine containing a ⁄ panama ⁄ (h n ) induced broader serological protection against heterovariant influenza virus strain a ⁄ fujian ⁄ than a subunit and a split influenza vaccine response of influenza vaccines against heterovariant influenza virus strains in adults with chronic diseases cross-protection by mf tmadjuvanted influenza vaccine: neutralizing and hemagglutinationinhibiting antibody activity against a (h n ) drifted influenza viruses quantifying influenza vaccine efficacy and antigenic distance detection of antibody to avian influenza a (h n ) virus in human serum by using a combination of serologic assays world health organization global influenza programme. who manual on animal influenza diagnosis and surveillance antigenic characterization of influenza b virus with a new microneutralisation assay: comparison to haemagglutination and sequence analysis seroprotection rate, meanfold increase, seroconversion rate: which parameter adequately expresses seroresponse to influenza vaccination? the adjuvanted influenza vaccines with novel adjuvants: experience with the mf -adjuvanted vaccine experimental inoculation of pigs with pandemic h n virus and hi cross-reactivity with contemporary swine influenza virus antisera current status of live attenuated influenza vaccine in the united states for seasonal and pandemic influenza failure of protection and enhanced pneumonia with a us h n swine influenza virus in pigs vaccinated with an inactivated classical swine h n vaccine isolation and characterization of h n influenza a virus from turkeys a new generation of modified live-attenuated avian influenza viruses using a two-strategy combination as potential vaccine candidates a dna transfection system for generation of influenza a virus from eight plasmids efficacy of inactivated swine influenza virus vaccines against the a ⁄ h n influenza virus in pigs mortality associated with influenza and respiratory syncytial virus on the united states realities and enigma of human viral influenza: pathogenesis, epidemiology and control immune response after adjuvant mucosal immunization of mice with inactivated influenza virus stimulation of protective and cross-protective imunity against influenza b virus after adjuvant mucosal immunization of mice protective and cross-protective mucosal immunization of mice by influenza virus type a with bacterial adjuvant synergistic action of cholera toxin b subunit (and escherichia coli heat-labile toxin b subunit) and a trace amount of cholera whole toxin as an adjuvant for nasal influenza vaccine effects of intanasal administration of chlera toxine (or escherichia coli heat-labila enterotoxin b subunits)supplemented with a trace amount of the holotoxin on the brain the adjuvants mf and lt-k enhance the mucosal and systemic immunogenicity of subunit influenza vaccine administrated intranasaly in mice generation of influenza vaccine strains by genetic reassortment a description of the process of seasonal and h n influenza vaccine virus selection and development pcr restriction analysis if genome composition and stability of cold-adapted reassortants live influenza vaccines options for live attenuated influenza vaccines (laiv) in the control of epidemic and pandemic influenza - characterization of an influenza a h n reassortant as a candidate for live-attenuated and inactivated vaccines against highly pathogenic h n viruses with pandemic potential are there alternative avian influenza viruses for generation of stable attenuated avian-human influenza a reassortant viruses? organization of production, quality control and provision of the republic of kazakhstan with the a ⁄ h n vaccine development of diagnostics and vaccines against influenza a ⁄ h n and a ⁄ h n is the basis for biological safety and protection of population in kazakhstan maior results of developing a technology for production of a pandemic influenza a ⁄ h n vaccine» abstract book ''options for the control of influenza vii abstract book international scientific conference of students, graduates and young scientists ''lomonosov isolation of influenza viruses in cell cultures and chicken embryos and their identification development of quality and safety control methods of the inactivated vaccine based on the strain a ⁄ astanarg ⁄ : ⁄ (h n control methods of medical immunobiological preparations injected to humans. guidelines, muk . / . . - (adopted by goskomsanepidnadzor rf ob scientific center for expertise of medical products, moscow. russian national pharmacopeia. ist edn the guidance for pre-clinical testing of pharmaceutical substances for safety and effectiveness (regulations of good laboratory practice in the russian federation -glp). manual on experimental (pre-clinical) assay of new pharmaceutical substances. moscow: ministry of public health ⁄ department of quality, effectiveness and safety control of medicines ⁄ scientific center of expert examination and national control of medicines ⁄ pharmacological national committee manual on experimental (pre-clinical) assay of new pharmaceutical substances. moscow: medline status of the development of influenza a ⁄ h n vaccines in the world and in russia approval of instruction for preclinical testing of pharmacological and medical substances in the repubilic of kazakhstan preclinical testing of new medical immunobiological substances. basic principles. moscow: ussr ministry of health order and methods of control of vaccine immunobiological safety. general methodic principles. moscow: ussr ministry of health planning and performance of clinical study of medicines federal pharmaceutical substances law. # -fz russian federation national standard. good clinical practice. # -st order of the minister of health of russian federation # signed . . . rules for clinical practice in russian federation a single-dose influenza a (h n ) vaccine safe and immunogenic in adult and elderly patients: an approach to pandemic vaccine development cross-reactive immunity to clade strains of influenza virus a subtype h n induced in adults and elderly patients by fluval, a prototype pandemic influenza virus vaccine derived by reverse genetics, formulated with a phosphate adjuvant, and directed to clade strains develop of domestic vaccinal and diagnostic preparations for influenza a ⁄ h n and a ⁄ h n as a basic principle of biological safety and security for the population of kazakhstan guidelines: ''isolation of influenza viruses in cell cultures and chicken embryos and their identification''. moscow: a-print validation of control methods for chemical and physicochemical characteristics of mibp quality: organization the guidance for pre-clinical testing of pharmaceutical substances for safety and effectiveness (regulations of good laboratory practice in the russian federation -glp). manual on experimental (pre-clinical) assay of new pharmaceutical substances. moscow: ministry of public health ⁄ department of quality, effectiveness and safety control of guidance on assessment of allergenic characteristics of pharmaceutical substances on adoption of the instructions for performance of pre-clinical assays and tests of pharmaceutical substances and medicines in the republic of kazakhstan national pharmacopoeia of the republic of kazakhstan planning and performance of clinical study of medicines federal law on medicines no. -aii dated national standard of the russian federation ''proper clinical practice'' no. -st guidance on clinical practice in the russian federation'' (in russian) aluminum hydroxide adjuvants activate caspase- and induce il- beta and il- release safety and immunogenicity of a pandemic influenza a h n vaccine when administered alone or simultaneously with the seasonal influenza vaccine for the - influenza season: a multicentre, randomised controlled trial current status of live attenuated influenza vaccine in the united states for seasonal and pandemic influenza a simple method of estimation fifty per cent endpoints use of animal models to understand the pandemic potential of highly pathogenic avian influenza viruses evaluation of replication and pathogenicity of avian influenza a h subtype viruses in a mouse model results of preclinical studies of live monovalent influenza vaccine influvir swine influenza a (h n ) infection in two children -southern california comparison of rna hybridization, hemagglutination assay, titration of infectious virus and immunofluorescence as methods for monitoring influenza virus replication in vitro concepts and procedures for laboratory-based influenza surveillance. us department of health and human services and pan-american health organization detection of antibody to avian influenza a (h n ) virus in human serum by using a combination of serologic assays fda ⁄ nih ⁄ who public workshop on immune correlates of protection against influenza a viruses in support of pandemic vaccine development coinfection of avian influenza virus (h n subtype) with infectious bronchitis live vaccine co-infection of staphylococcus aureus or haemophilus paragallinarum exacerbates h n influenza a virus infection in chickens human infection with an avian h n influenza a virus in hong kong in avian-to-human transmission of h n subtype influenza a viruses: relationship between h n and h n human isolates human infection with influenza h n universal primer set for the full-length amplification of all influenza a viruses phylogenetic analysis of hemagglutinin and neuraminidase genes of h n viruses isolated from migratory ducks the neighbor-joining method: a new method for reconstructing phylogenetic trees application of a microtechnique to viral serological investigations biological activity of monoclonal antibodies to operationally defined antigenic regions on the hemagglutinin molecule of a ⁄ seal ⁄ massachusetts ⁄ ⁄ (h n ) influenza virus development of vaccine strains of h and h influenza viruses isolation of ortho-and paramyxoviruses from feral birds in hokkaido head-to-head comparison of four nonadjuvanted inactivated cell culture-derived influenza vaccines: effect of comparison, spatial organization and immunization route on the immunogenicity in a murine challenge model evaluation of growth, genetic, and antigenic characteristics of pandemic h n viruses isolated and passaged in qualified mdck suspension cells a (h n ) influenza virus pandemic: a review influenza vaccine: from surveillance through production to protection trivalent mdck cell culture-derived influenza vaccine optaflu (novartis vaccines) validation of the safety of mdck cells as a substrate for the production of a cell-derived influenza vaccine genetic composition of a high-yielding influenza a virus recombinant: a vaccine strain against ''swine'' influenza rescue of influenza a virus from recombinant dna of health, public health service. concepts and procedures for laboratory based influenza surveillance a rapid method for immunotitration of influenza viruses using flow cytometry generation of live attenuated novel influenza a ⁄ california ⁄ ⁄ (h n ) vaccines with high yield in embryonated chicken eggs haemagglutinin quantification and identification of influenza a&b strains propagated in per.c cells: a novel rp-hplc method comparison of egg and high yielding mdck cell-derived live attenuated influenza virus for commercial production of trivalent influenza vaccine: in vitro cell susceptibility and influenza virus replication kinetics in permissive and semi-permissive cells effect of neuraminidase antibody on hong kong influenza infection-permissive immunization with influenza virus neuraminidase prevents weight loss in infected mice protection of mice with recombinant influenza virus neuraminidase cross-reactive neuraminidase antibodies afford partial protection against h n in mice and are present in unexposed humans note for guidance on harmonization of requirements for influenza vaccines who meeting on the role of neuraminidase in inducing protective immunity against influenza infection who manual on animal influenza diagnosis and surveillance [electronic resource] ⁄ world health organization, department of communicable disease surveillance and response measurement of anti-influenza neuraminidase antibody using a peroxidase-linked lectin and microtitre plates coated with natural substrates detection of antibody to avian influenza a(h n ) virus in human serum by using a combination of serologic assays large trials confirm immunogenicity of h n vaccines pre-existing immunity against swine-origin h n influenza viruses in the general human population yuelong shu references novel swine-origin influenza a (h n ) virus investigation team. emergence of a novel swine-origin influenza a (h n ) virus in humans serum crossreactive antibody response to a novel influenza a (h n ) virus after vaccination with seasonal influenza vaccine detection of antibody to avian influenza a (h n ) virus in human serum by using a combination of serologic assays concepts and procedures for laboratory-based influenza surveillance manual on animal influenza diagnosis note for guidance on harmonization of requirements for influenza vaccines (cpmp ⁄ bwp ⁄ ⁄ ). european agency for the evaluation of medicinal products cross-reactive antibody responses to the pandemic h n influenza virus serologic survey of pandemic (h n ) virus influenza a(h n ) seroconversion rates and risk factors among distinct adult cohorts in singapore swine influenza a outbreak reflections on the swine flu vaccination program the flu and other influenza pandemics: ''over there'' and back again evidence of an absence: the genetic origins of the pandemic influenza virus the influenza virus: a killer comes into view antigenic and genetic characteristics of swine-origin a(h n ) influenza viruses circulating in humans pathogenesis and immunogenicity of influenza viruses with genes from the pandemic virus lifetime of plasma cells in the bone marrow humoral immunity due to long-lived plasma cells no one is naive: the significance of heterologous t-cell immunity infection outcomes in patients with common variable immunodeficiency disorders: relationship to immunoglobulin therapy over years signaling by toll-like receptors and requires bruton's tyrosine kinase antiviral cytotoxic t-cell memory by vaccination with recombinant listeria monocytogenes cell-mediated immune response of human lymphocytes to influenza a ⁄ ussr (h n ) virus infection severe deficiency of switched memory b cells (cd (+)igm(-)igd(-)) in subgroups of patients with common variable immunodeficiency: a new approach to classify a heterogeneous disease an early humoral immune response in peripheral blood following parenteral inactivated influenza vaccination multifunctional th cells define a correlate of vaccine-mediated protection against leishmania major note for guidance on harmonization of requirements for influenza vaccines (cpmp ⁄ bwp ⁄ ⁄ ) active vaccination in patients with common variable immunodeficiency (cvid) serum bactericidal antibody response to serogroup c polysaccharide meningococcal vaccination in children with primary antibody deficiencies specific anti-influenza virus antibody production in vitro by lymphocytes from a subset of patients with hypogammaglobulinemia shu a a state key laboratory for infectious disease control and prevention, national institute for viral disease control and prevention, chinese center for disease control and prevention, beijing, china. b state key laboratory for molecular virology and genetic engineering, national institute for viral disease control and prevention roles of adjuvant igv combined with influenza m e based virus like particle in the immune response and cross protection usa) ae h at °c. tetramethylbenzidine (tmb) was applied, and the optical den epidemiology and pathogenesis of influenza epidemiology and virology of influenza illness influenza vaccine: the challenge of antigenic drift evolving strategies for the prevention of influenza infection: potential for multistrains targeting a ''universal human influenza'' a vaccine universal influenza a vaccine: optimization of m -based constructs the epitope recognized by a monoclonal antibody in influenza a virus m protein is immunogenic and confers immune protection high-epitope density in a single recombinant protein molecule of the extracellular domain of influenza a virus m protein significantly enhances protective immunity pre-clinical study of influenza virus a m peptide conjugate vaccines in mice, ferrets, and rhesus monkeys induction of influenza type a virus-specific resistance by immunization of mice with a synthetic multiple antigenic peptide vaccine that contains ectodomains of matrix protein a universal influenza a vaccine based on the extracellular domain of the m protein protective immunity against influenza a virus induced by immunization with dna plasmid containing influenza m gene protection against influenza virus challenged by topical application of influenza dna vaccine influenza a vaccine based on the extracellular domain of m : weak protection mediated via antibody-dependent nk cell activity t cell immunoglobulin mucin- crystal structure reveals a novel ligand binding surface structures of t cell immunoglobulin mucin protein show a metal-ion-dependent ligand binding site where phosphatidylserine binds structures of t cell immunoglobulin mucin receptors and reveal mechanisms for regulation of immune responses by the tim receptor family the tim gene family: emerging roles in immunity and disease th -specific cell surface protein tim- regulates macrophage activation and severity of and autoimmune disease identification of a surface glycoprotein on african green monkey kidney cells as a receptor for hepatitis a virus the igv domain of human b - (cd ) is sufficient to co-stimulate t lymphocytes and induce cytokine secretion vaccination with cell immunoglobulin mucin- antibodies and inactivated influenza enhances vaccine-specific lymphocyte proliferation, interferon-r production and cross-strain reactivity incorporation of membrane-anchored flagellin into influenza virus-like particles enhances the breadth of immune response virus-like particle induces protective immunity against homologous and heterologous strains of influenza virus site accessed on st study designs for timely estimation of influenza vaccine effectiveness using european sentinel practitioner networks a new influenza surveillance system in france: the ile-de-france ''grog''. . principles and methodology site accessed on st i-move'' towards monitoring seasonal and pandemic influenza vaccine effectiveness: lessons learnt from a pilot multi-centric case-control study in europe population and risk group uptake of h n influenza vaccine in mainland france - : results of a national vaccination campaign of global health and emerging pathogens ns deletions convert the -h n pandemic virus into a live attenuated vaccine. influenza and other respiratory viruses the influenza virus enigma vaccine production capacity for seasonal and pandemic (h n ) influenza interferon-induced isg conjugation inhibits influenza a virus gene expression and replication in human cells the multifunctional ns protein of influenza a viruses influenza a and b viruses expressing altered ns proteins: a vaccine approach multiple anti-interferon actions of the influenza a virus ns protein the ns protein of a human influenza virus inhibits type i interferon production and the induction of antiviral responses in primary human dendritic and respiratory epithelial cells immunization with live attenuated influenza viruses that express altered ns proteins results in potent and protective memory cd + t-cell responses plasmacytoid dendritic cells delineate immunogenicity of influenza vaccine subtypes regulation of adaptive immunity by the innate immune system the influenza virus ns protein: inhibitor of innate and adaptive immunity single-reaction genomic amplification accelerates sequencing and vaccine production for classical and swine origin human influenza a viruses unidirectional rna polymerase i-polymerase ii transcription system for the generation of influenza a virus from eight plasmids avian influenza (h n ) viruses isolated from humans in asia in exhibit increased virulence in mammals transmission and pathogenesis of swine-origin a(h n ) influenza viruses in ferrets and mice a naturally occurring deletion in its ns gene contributes to the attenuation of an h n swine influenza virus in chickens future influenza vaccines and use of genetic recombinants eight-plasmid system for rapid generation of influenza virus vaccines rescue of influenza b virus from eight plasmid high yield reassortants of influenza type b viruses np gene obtained from high yield donor. options for control of influenza vi. abstract # summary of status of development and availability of b ⁄ brisbane ⁄ ⁄ -like candidate vaccine viruses and potency testing reagent reassortants of influenza b viruses for use in vaccines: an evaluation preparation of influenza b virus recombinant strains genetic and phenotypic analysis of reassortants of high growth and low growth strains of influenza b virues pandemic influenza in russia: detection and molecular references evolutionary pattern of pandemic influenza (h n ) virus in the late phases of the pandemic antigenic and genetic characteristics of swine-origin a(h n ) influenza viruses circulating in humans effects of egg adaptation on the receptor-binding properties of human influenza a and b viruses the early diversification of influenza a ⁄ h n pdm update on influenza a (h n ) monovalent vaccines clinical and epidemiologic characteristics of early cases of influenza a pandemic options for the control of influenza vii virus infection, people's republic of china genome evolution of novel influenza a (h n ) viruses in humans introduction and transmission of pandemic influenza a (h n ) virus -kenya emergence of a novel swine-origin influenza a (h n ) virus in humans first season of h n influenza origins and evolutionary genomics of the swine-origin h n influenza a epidemic modeling gene sequences over time in h n influenza a virus populations differentiation of two distinct clusters among currently circulating influenza a(h n )v viruses conversion of mdck cell line to suspension culture by transfecting with human siat e gene and its application for influenza virus production trivalent mdck cell culture-derived influenza vaccine optaflu (novartis vaccines) use of mdck cells for production of live attenuated influenza vaccine flow cytometric monitoring of influenza a virus infection in mdck cells during vaccine production cd-hit: a fast program for clustering and comparing large sets of protein or nucleotide sequences seroprevalence following the second wave of pandemic molecular evolution of human influenza a viruses in a local area during eight influenza epidemics from evaluation of hemagglutinin subtype swine influenza viruses from the united states the early molecular epidemiology of the swine-origin a ⁄ h n human influenza pandemic the genomic and epidemiological dynamics of human influenza a virus reconstructing the initial global spread of a human influenza pandemic: a bayesian spatial-temporal model for the global spread of h n pdm mild form of h n influenza infection detected by active surveillance: implications for infection control the pandemic (h n ) swine influenza virus is mild compared to the pandemic (h n ) virus because of a prolineto-serine substitution in the receptor-binding site of its hemagglutinin -a hypothesis pathogenesis and transmission of swine-origin a(h n ) influenza virus in ferrets investigation of the first cases of human-to-human infection with the new swine-origin influenza a (h n ) virus in canada antigenic and genetic characteristics of swine-origin a(h n ) influenza viruses circulating in humans molecular evolution of hemagglutinin genes of h n swine and human influenza a viruses antigenic structure of influenza virus haemagglutinin defined by hybridoma antibodies the predicted antigenicity of the haemagglutinin of the spanish influenza pandemic suggests an avian origin genetically destined potentials for nlinked glycosylation of influenza virus hemagglutinin global patterns of influenza a virus in wild birds antigenic and genetic characteristics of swine-origin a (h n ) influenza viruses circulating in humans translatorx: multiple alignment of nucleotide sequences guided by amino acid translations raxml-iii: a fast program for maximum likelihood-based inference of large phylogenetic trees flugenome: a web tool for genotyping influenza a virus beast: bayesian evolutionary analysis by sampling trees origin and evolution of influenza virus hemagglutinin genes panorama phylogenetic diversity and distribution of type a influenza virus early alterations of the receptor-binding properties of h , h , and h avian influenza virus hemagglutinins after their introduction into mammals human influenza a h n virus related to a highly pathogenic avian influenza virus origin and evolutionary genomics of the swine-origin h n influenza a epidemic keywords novel influenza viruses, oseltamivir resistance phylogenetic analyses of pandemic influenza viruses textbook of influenza mapping the antigenic and genetic evolution of influenza virus cdc protocol of realtime rt-pcr for swine influenza a(h n ) revision the hemagglutination and hemagglutination ingibitions test. who collaborating center for surveillance molecular evolutionary genetics analysis (mega) software version . pandemic influenza: an inconvenient mutation large-scale sequencing of human influenza reveals the dynamic nature of viral genome evolution origin and evolutionary genomics of the swine-origin h n influenza a epidemic antigenic and genetic characteristics of swine-origin a (h n ) influenza viruses circulating in humans genetic subtyping using cluster analysis panorama phylogenetic diversity and distribution of type a influenza virus continuing progress towards a unified nomenclature for the highly pathogenic h n avian influenza viruses: divergence of clade . viruses the influenza virus resource at the national center for biotechnology information muscle: multiple sequence alignment with high accuracy and high throughput multiple alignment of dna sequences with mafft raxml-iii: a fast program for maximum likelihood-based inference of large phylogenetic trees flugenome: a web tool for genotyping influenza a virus evolution of influenza viral neuraminidase (na) genes revealed by large-scale sequence analysis. proceedings of the options for the control of influenza vii a quantitative genotype algorithm reflecting h n avian influenza niches xiu-feng wan a a department of basic sciences complete composition vector, influenza a virus, minimum spanning tree, phylogeny, progenitor ipminer: a progenitor gene identifier for influenza a virus avian-to-human transmission of the pb gene of influenza a viruses in the and pandemics triple-reassortant swine influenza a (h ) in humans in the united states clustal w: improving the sensitivity of progressive multiple sequence alignment through sequence weighing, positionspecific gap penalties and weight matrix choice muscle: multiple sequence alignment with high accuracy and high throughput coffee: an objective function for multiple sequence alignments the neighbour-joining method: a new method for reconstructing phylogenetic trees mrbayes: bayesian inference of phylogenetic trees basic local alignment search tool a quantitative genotype algorithm reflecting h n avian influenza niches computational identification of reassortments in avian influenza viruses ubiquitous reassortments in influenza a viruses phylip -phylogeny inference package (version . ) pandemic influenza in russia: isolation, antigenic produced in our laboratory. normal equine serum was purchased from sigma (usa) comparative data on the development of influenza pandemic in russia and in the other european countries (in russian). materials of the ii annual all-russian congress on infectious diseases isolation on . . and deposition in the state virus collection of the first strain a ⁄ moscow ⁄ ⁄ (h n )swl, similar to the swine virus a(h n ) from the first patient diagnosed in moscow isolation of influenza viruses in cell cultures and in chicken embryos and their identification. methods guidance (in russian) molecular genetic characterization of the strains of pandemic influenza a(h n )v isolated on the territory of russian federation in (in russian). materials of the ii annual all-russian congress on infectious diseases genetic and antigenic analyses of influenza a (h n ) viruses, - sialic acid receptor detection in the human respiratory tract: evidence for widespread distribution of potential binding sites for human and avian influenza viruses pandemic influenza a(h n ) virus mutations reported to be associated with severe disease antigenic and genetic characteristics of swine-origin a(h n ) influenza viruses circulating in humans barr b,c a novartis vaccines and diagnostics gmbh, marburg, germany. b who collaborating centre for reference and research on influenza co-infecting viruses in pandemic h n and seasonal influenza positive human respiratory samples emergence of a novel swine-origin influenza a (h n ) virus in humans simultaneous detection and high-throughput identification of a panel of rna viruses causing respiratory tract infections comparison of multiple commercial assays for the detection of swine-origin influenza a (h n ) virus (soiv) evidence from multiplex molecular assays for complex multipathogen interactions in acute respiratory infections performance comparison of res-plex ii and xtag rvp fast for detecting respiratory viruses clinical virology symposium communityacquired respiratory co-infection (carc) in critically ill patients infected with pandemic influenza a (h n ) virus infection bacterial co-infections in lung tissue specimens from fatal cases of pandemic influenza a (h n ) -united states a quantitative risk assessment of exposure to adventitious agents in a cell culture-derived subunit influenza vaccine john's hopkins bloomberg school of public health design of an automated laboratory for high-throughput influenza surveillance human influenza surveillance: the demand to expand influenza: an emerging disease avian-to-human transmission of the pb gene of influenza a viruses in the and pandemics proinflammatory cytokine responses induced by influenza a (h n ) viruses in primary human alveolar and bronchial epithelial cells induction of proinflammatory cytokines in human macrophages by influenza a (h n ) viruses: a mechanism for the unusual severity of human disease? influenza h n and h n virus replication and innate immune responses in bronchial epithelial cells are influenced by the state of differentiation mapping of the two overlapping genes for polypepetides ns and ns on rna segment of influenza virus genome sequences of mrnas derived from genome rna segment of influenza virus: collinear and interrupted mrnas code for overlapping proteins influenza virus ns protein inhibits pre-mrna splicing and blocks mrna nucleocytoplasmic transport the influenza virus ns protein: a novel inhibitor of pre-mrna splicing identification of cis-acting intron and exon regions in influenza virus ns mrna that inhibit splicing and cause the formation of aberrantly sedimenting presplicing complexes identification of a second protein encoded by influenza c virus rna segment influenza c virus ns protein upregulates the splicing of viral mrnas identification of an amino acid residue on influenza c virus m protein responsible for formation of the cord-like structures of the virus a mutation on influenza c virus m protein affects virion morphology by altering the membrane affinity of the protein detection of ion channel activity in xenopus laevis oocytes expressing influenza c virus cm protein evidence that the cm protein of influenza c virus can modify the ph of the exocytic pathway of transfected cells the ion channel activity of the influenza virus m protein affects transport through the golgi apparatus intracellular localization of influenza c virus ns protein (nep) in infected cells and its incorporation into virions receptor specificity, host range and pathogenicity of influenza viruses replication, pathogenesis and transmission of pandemic (h n ) virus in non-immune pigs world health organization. preliminary review of d g amino acid substitution in the haemagglutinin of pandemic influenza a (h n ) viruses observed association between the ha mutation d g in the pandemic influenza a(h n ) virus and severe clinical outcome quasispecies of the d g substitution in the hemagglutinin of pandemic influenza a(h n ) virus from patients with severe disease in hong kong a possible association of fatal pneumonia with mutations of pandemic influenza a ⁄ h n sw virus in the receptor-binding site of the ha subunit severe outcome of influenza a ⁄ h n ⁄ v infection associated with g ⁄ n polymorphisms in the haemagglutinin: a multicenter study influenza pandemic caused by highly conserved viruses with two receptor-binding variants overexpression of the alpha- , -sialyltransferase in mdck cells increases influenza virus sensitivity to neuraminidase inhibitors human and avian influenza viruses target different cell types in cultures of human airway epithelium avian-virus-like receptor specificity of the hemagglutinin impedes influenza virus replication in cultures of human airway epithelium receptor-binding specificity of pandemic influenza a (h n ) virus determined by carbohydrate microarray fields virology. philadelphia, pa: lippincott williams & wilkins the molecular virology and reverse genetics of influenza c virus identification of a second protein encoded by influenza c virus rna segment identification of a amino acid protein encoded by rna segment of influenza c virus influenza c virus cm protein is produced from a amino acid protein (p ) by signal peptidase cleavage a mutation on influenza c virus m protein affects virion morphology by altering the membrane affinity of the protein influenza c virus cm integral membrane glycoprotein is produced from a polypeptide precursor by cleavage of an internal signal sequence evidence that the matrix protein of influenza c virus is coded for by a spliced mrna functional properties of the virus ion channels the cm protein of influenza c virus is an oligomeric integral membrane glycoprotein structurally analogous to influenza a virus m and influenza b virus nb proteins characterization of a second protein (cm ) encoded by rna segment of influenza c virus phosphorylation of influenza c virus cm protein the sites for fatty acylation, phosphorylation and intermolecular disulphide bond formation of influenza c virus cm protein identification of an amino acid residue on influenza c virus m protein responsible for formation of the cord-like structures of the virus a human melanoma cell line highly susceptible to influenza c virus antigenic characterization of the nucleoprotein and matrix protein of influenza c virus with monoclonal antibodies construction of an antigenic map of the haemagglutinin-esterase protein of influenza c virus the synthesis of polypeptides in influenza c virus-infected cells new low-viscosity overlay medium for viral plaque assays the influenza virus m protein cytoplasmic tail interacts with the m protein and influences virus assembly at the site of virus budding the cytoplasmic tail of the influenza a virus m protein plays a role in viral assembly the influenza a virus m cytoplasmic tail is required for infectious virus production and efficient genome packaging distinct domains of the influenza a virus m protein cytoplasmic tail mediate binding to the m protein and facilitate infectious virus production influenza virus m ion channel protein is necessary for filamentous virion formation influenza h n virus infection of polarized human alveolar epithelial cells and lung microvascular endothelial cells das inhibits h n influenza virus infection of human lung tissues receptor binding specificity of recent human h n influenza viruses differential onset of apoptosis in avian influenza h n and seasonal h n virus infected human bronchial and alveolar epithelial cells: an in vitro and ex vivo study human influenza virus a ⁄ hongkong ⁄ ⁄ (h n ) infection induction of proinflammatory cytokines in human macrophages by influenza a (h n ) viruses: a mechanism for the unusual severity of human disease? proinflammatory cytokine responses induced by influenza a (h n ) viruses in primary human alveolar and bronchial epithelial cells differential onset of apoptosis in influenza a virus h n -and h n -infected human blood macrophages avian flu: influenza virus receptors in the human airway haemagglutinin mutations responsible for the binding of h n influenza a viruses to humantype receptors an avian influenza h n virus that binds to a human-type receptor evolution of highly pathogenic h n avian influenza viruses in vietnam between evolutionary dynamics and emergence of panzootic h n influenza viruses writing committee of the second world health organization consultation on clinical aspects of human infection with avian influenza a (h n ) virus recent avian h n viruses exhibit increased propensity for acquiring human receptor specificity a simple screening assay for receptor switching of avian influenza viruses glycan topology determines human adaptation of avian h n virus hemagglutinin h n chicken influenza viruses display a high binding affinity for neu acalpha - galbeta - ( -hso )glcnac-containing receptors a strain of human influenza a virus binds to extended but not short gangliosides as assayed by thin-layer chromatography overlay search for additional influenza virus to cell interactions avian flu: isolation of drug-resistant h n virus the surface glycoproteins of h influenza viruses isolated from humans, chickens, and wild aquatic birds have distinguishable properties this study was supported by the li ka shing foundation, the national institutes of health (niaid contract hhsn c), and the area of excellence scheme of the university grants committee (grant aoe ⁄ m- ⁄ ) of the hong kong sar government. this work was supported by the national institute of allergy and infectious diseases (niaid) contract hhsn c, the li ka shing foundation, and we thank all french and vietnamese field staff involved in the data collection in viet nam for their enthusiasm and support and we are grateful to the pig farmers participating in the study for their cooperation and patience. this study was a part of the gripavi project and was funded by the french ministry of foreign affairs. this research was supported in part by the national institute of allergy and infectious diseases (niaid) contract hhsn c and the area of excellence scheme of the university grants commission (grant aoe ⁄ m- ⁄ ) of the hong kong sar government. we acknowledge the food and environmental hygiene department of hong kong for facilitating the study. this work was supported by the national institute of allergy and infectious diseases (niaid) contract hhsn c, the li ka shing foundation, and the area of excellence scheme of the university grants committee (grant aoe ⁄ m- ⁄ ) of the hong kong sar government. we gratefully acknowledge our colleagues from iiii, shantou university and skleid, hku for their excellent technical assistance. the study was supported by the rfcid commissioned study (lab# ) from research fund secretariat, food and health bureau, hong kong sar; area of excellence scheme of the university grants committee (grant aoe ⁄ m- ⁄ ), hong kong sar; and by niaid contract (sjceirs, hhsn c), nih, usa.ferrets in all groups inoculated with a ⁄ turkey ⁄ ⁄ virus survived the infection and were observed once daily for days. below lower limit of detection (< ae log eid ⁄ ml).statistical cutoff of ic values for nai susceptibility, determined by x ae + iqr. outliers with ic above this cutoff and > times the mean ic for each drug were characterized as extreme outliers; those with known drug-resistance mutations such as h y were classified as resistant and analyzed separately. h wildtype, oseltamivir-susceptible isolates. h y variants, oseltamivir-resistant virus isolates. iqr, interquartile ranges; nai, neuraminidase inhibitors. we wish to thank our collaborators in the who global influenza surveillance network and united states public health laboratories for the submission of virus isolates and clinical specimens. we also thank our colleagues from the virus reference team and the influenza sequence activity, influenza division, cdc, for their valuable technical assis-the findings and conclusions of this report are those of the authors and do not necessarily represent the views of the centers for disease control and prevention (cdc). we are indebted to yonas araya, theresa wolter, and ivan gomez-osorio for their excellent laboratory techniques and animal handling assistance. we would like to thank andrea ferrero for her laboratory managerial skills. this research was possible through funding by the cdc-hhs grant ( u ci ), niaid-nih grant, (r ai ), csrees-usda grant ( - ), and niaid-nih contract (hhsn c). we thank c bazzoli for advice. this work was supported by a grant from the european union fp project flu-modcont (no. ). we thank staff at seoul, incheon, daejeon, gwangju, gangwon, and jeonbuk provincial research institute of health and environments for their laboratory testing. additionally, we would like to acknowledge the contributions of participating sentinel doctors for evaluating the new rat kit. this study was supported by a grant from the korea cdc. we thank roche applied science for providing the materials and equipment for this evaluation. this research was supported in part by the national institute of allergy and infectious diseases (niaid) contract hhsn c and the area of excellence scheme of the university grants committee (grant aoe ⁄ m- ⁄ ) of the hong kong sar government. the authors would like express their sincere thanks to cdc, usa for supporting the routine surveillance of ili in we would like to acknowledge the australian red cross blood service (the blood service) and the australian government, which fully fund the blood service for the provision of blood products and services to the australian community. we also wish to thank the donors and staff of the blood service, who have assisted in provision of specimens for testing in this protocol, as well as the staff at the who we are grateful to liping long for her assistance in map generation. this project was supported by nih niaid rc ai . cz is supported partially by canadian nserc postdoc fellowship. the authors thank the national investigation team based at the national institute of health (istituto superiore di sanita'), italy (in particular antonino bella, maria cristina rota, stefania salmaso) for providing their support in data collection, and the european union this study was supported in part by a grant-in-aid ( ) and the special coordination funds for promoting science and technology of ministry of education, science, sports and culture of japan. this study was supported in part by a grant-in-aid from the ministry of education, science, and culture of japan ( ) and the special coordination funds for promoting science and technology of mext of japan. the work described here was supported by phs grant ai- (jam) and alsac. we thank all authors for their participation in data gathering and analysis, and in writing this manuscript. the studies were funded by gsk consumer healthcare, and gsk investigators were involved in all stages of the study conduct and analysis. py, po, dw and kb are employees of glaxosmithkline. this study was funded by glaxosmithkline. we thank all authors for their participation in data gathering and analysis, and in writing this manuscript. the studies were funded by gsk consumer healthcare, and gsk investigators were involved in all stages of the study conduct and analysis. this study was funded by glaxosmithkline. we thank all authors for their participation in data gathering and analysis, and in writing this manuscript. the stud- authors are thankful to path for the financial support of this research. we would like to acknowledge jessica d'amico and dr. rick bright of path for their editorial review. this study was supported by path. the authors would like to thank rick bright, jessica d'amico, and vadim tsvetnitsky for editing assistance. the we thank dr. m. enami (kanazawa university) for generously providing plasmids containing cdnas to influenza a virus m and ns genes. we also gratefully thank dr. r. sho (department of public health, yamagata university faculty of medicine) for statistical analysis. some data shown in this study have also been presented in the reference paper. this work was supported in part by a grant-in-aid for scientific research from the ministry of education, culture, sports, science, and technology, japan, takeda science foundation, terumo life science foundation, and a grant-in-aid from the global coe program of the japan society for the promotion of science. we thank markus eickmann for his help in isolation and initial characterization of a ⁄ hamburg ⁄ ⁄ and for providing antisera against h n pdm. this study was supported by the european union fp global a(h n ) genetic characterization, molecular evolution dynamics, antiviral susceptibility profiles, and inference of public health implications require nation and region wide systematic analysis of circulating virus. in this study we analysed the genetic and antiviral drug susceptibility profiles of pandemic a(h n ) influenza virus circulating in portugal. genetic profile analysis was performed in isolates to the hemagglutinin (ha), neuraminidase (na) and mp genes, and in six of these isolates the pb , pb , pa, np and ns genes were also analysed. antiviral drug susceptibility profile was analysed for isolates, phenotypically and genotypically to neuraminidase inhibitors (nai) and genotypically to amantadine. the point mutations identified in ha, na, and mp genes of different strains do not seem to evidence an evolutionary trend. this is in agreement with the genetic and antigenic homogeneity that has being described for a(h n ) virus. all analysed strains were found to be resistant to amantadine, and five of these strains exhibited a reduced susceptibility profile to nai, three only for oseltamivir and two for both inhibitors. introduction: the dynamics of pandemic influenza a ⁄ h n compared to seasonal strains of influenza is not clearly understood. it is important to understand the patterns of viral shedding and symptoms over time in community-based infections.materials and methods: household infections were followed-up in two large community-based studies. patterns of viral shedding, symptoms and signs, and tympanic temperature were plotted over time and grouped according to strain for analysis.results: the patterns of viral shedding, symptoms and signs, and tympanic temperature in three influenza a strains (pandemic a ⁄ h n , seasonal a ⁄ h n , and seasonal a ⁄ h n ) were comparable. peak viral shedding occurred close to the onset of symptoms and resolved after - days. patterns of viral shedding in influenza b virus infections differed.discussion: the patterns of viral shedding and clinical course of pandemic influenza a ⁄ h n infections were broadly similar to seasonal influenza a ⁄ h n and a ⁄ h n . only the clinical course of seasonal influenza b infections was similar to pandemic influenza a ⁄ h n . the dynamics of pandemic influenza a ⁄ h n were observed to be largely alike to the dynamics of seasonal influenza a ⁄ h n and a ⁄ h n . the coated respirators inactivated a broad range of influenza strains within minute, including the pandemic strain and human, swine, and avian influenza viruses. antiviral effectiveness was not reduced by hot, humid conditions or repeated saturation, which might occur during prolonged use of respirators. in contrast, infectious virions were detected on the surfaces of all uncoated ffp respirators, and could be transferred to glove surfaces during handling of contaminated masks. growth of the viruses was monitored by ha titer using turkey red blood cells, by quantitative real time rt-pcr (qrt-pcr) to detect the influenza a matrix gene, and also by flow cytometry to detect virus positive cells using monoclonal antibodies (imagen influenza virus a and b). , matrix gene copy number was determined using qrt-pcr and analysed using the sequence detection software on a fast system sds (applied biosystems, california, usa). further characterisation was performed through sequence analysis and the ha inhibition (hai) assay. sequence analysis was performed using dnastar and all sequences obtained were compared with the sequence of either the original clinical specimen if available or the conventional atcc derived mdck cell isolate. the hai assay was used to characterize the viruses against a panel of known standard reference viruses and their homologous ferret antiserum.options for the control of influenza vii abstract background: we measured the cross-reactive antibody response to pandemic h n in children and adults before and after vaccination with [ ] [ ] [ ] [ ] influenza season vaccines as part of the rapid public health response to the emergence of ph n and to provide evidence for ph n vaccination policy development in mainland china. materials and methods: archived serum specimens from previous vaccine studies were detected by hemagglutination inhibition assay. results: limited crossreactive antibody response to ph n had been detected among participants of all age groups before and after they had been vaccinated with - , - influenza seasonal vaccines. vaccination with seasonal influenza viruses resulted in limited seroconversion to ph n in all age groups, compared with - % of seroconversion to seasonal influenza viruses. but similar to recent studies, a peak of cross-reactive antibody response to ph n was observed in % and % of participants born from to before and after vaccination. conclusions: in order to protect our populations in china, our study strongly suggests vaccination with ph n is required in all age groups and that older populations born before may be associated with a lower infection rate of ph n . on april and april , , cases of ph n were identified in specimens obtained from two epidemiologically unlinked patients in the united states and soon thereafter in texas and mexico. since that time, the virus has spread across the globe. assessment of cross-reactive antibody response to the ph n after vaccination with sea-sonal influenza vaccine was first reported from us centers of disease control and prevention (us cdc). according to their results, the seasonal influenza vaccines provided little or no protection against the ph n , but some degree of preexisting immunity to the virus existed, especially among adults aged ‡ years. in this study, using archived serum samples from previous vaccine studies, we measure the level of cross-reactive antibody response to ph n in children and adults vaccinated intramuscularly with trivalent inactivated vaccine developed for the northern hemi- serum specimens were collected and provided by provincial centers for disease control and prevention of china as a public health response to the emergence of ph n exempt from human-subjects review. a total of serum samples were collected from xinjiang uygur autonomous region, yunnan, and shandong provinces. all the serum specimens were grouped by the age of subjects ( - , - , - , ‡ years) and by different influenza seasons.hemagglutination inhibition assay was performed according to standard procedures in this study. [ ] [ ] [ ] as with h n components of the vaccine, the seasonal influenza viruses used in this study were a ⁄ solomon islands ⁄ ⁄ and a ⁄ brisbane ⁄ ⁄ . the ph n influenza virus used in this study was a ⁄ california ⁄ ⁄ provided by us cdc. all the viruses were propagated in specific pathogenfree embryonated chicken eggs and inactivated by & paraformaldehyde. the criteria recommended by the european agency for the evaluation of medical product was applied for the assessment of seasonal influenza vaccine gmt, geometric mean titer; hi, hemagglutination inhibition. three weeks after boosting immunization, spleens were harvested from immunized and control mice. splenocytes were prepared by lymphocyte separation media (ez-sepÔ, shen zhen, china). the cells were washed and resuspended in complete rpmi- containing fetal bovine serum (hyclone, logan, ut, usa), glutamax, um b-me. splenocytes were cultured in vitro in the presence of inactivated h n , h n , h n , and h n influenza virus antigen for h. quick cell proliferation assay kit (biovision, san francisco, ca, usa) was used to detect the cell proliferation. the - nm absorbance was read on a plate reader. all experiments have been repeated at least three times.results are presented as mean standard error of the mean (sem). comparison of the data was performed using the student's t-test. significance was defined as a p value of < ae . to evaluate the adjuvant effect of recombinant igv, the anti m e antibody subclasses was measured. igg and igg a were detected after the first and second immunization ( table ). the ratio of igg a ⁄ igg was calculated. immunization with only m e-hbc showed a lower igg a ⁄ igg ratio < ae . igv combined with m e-hbc led to a high igg a ⁄ igg ratio of up to - after first and second immunization. these igg subclass distributions indicated that igv can induce a th immune response. to determine whether the splenocytes were stimulated in vitro with different subtypes of inactivated influenza antigen after the igv plus m e-hbc antigen immunization, h n , h n , h n , h n inactivated antigen was used table . the serum igg, igg , igg a, and igg a ⁄ igg ratio were measured by elisa after first and second immunization. m e were coated on the wells plate overnight, and serial dilution sera of day , , after first and second immunization were added , ae , , , , ug ⁄ ml of igg, igg , igg a purified antibody were also added for obtaining the standard curve. hrp-labeled goat anti-mouse igg, igg , or igg a was then added, washed, and the optical density was read at nm. the results were showed at mean ± sem. day after first immunization days after second immunizationoptions for the control of influenza vii the french grog (groupes régionaux d'observation de la grippe) early warning network collects more than specimens yearly from cases of acute respiratory illness (ari), using two sampling methods: systematic randomized and non systematic ''ad hoc'' sampling. although vaccines against influenza a virus are the most effective method by which to combat infection, it is clear that their production needs to be accelerated and their efficacy improved. a panel of recombinant live attenuated human influenza a vaccines (laivs), including ns - , ns - , nsd , were generated by rationally engineering mutations directly into the genome of a pandemic-h n virus. the vaccine potential of each laiv was determined through analysis of attenuation, immunogenicity, and their ability to protect mice and ferrets. the data indicate that the novel nsd -laiv was ideally attenuated and elicited strong protective immunity. this study also shows that attenuating mutations can be rapidly engineered into the genomes of emerging ⁄ circulating influenza a viruses in order to produce laivs. the influenza virus exhibits complicated evolutionary dynamics due to multiple reasons, such as diverse hosts, high mutation rates, and rapid replications. in this study, large-scale analyses of influenza neuraminidase (na) sequences revealed influenza a and b na genes diverged first around years ago, and subsequently the na subtypes of influenza a emerged around years ago. all nine na subtypes of influenza a were genetically distinct from each other, with a total of lineages identified. in addition, five and three sub-lineages were further identified in lineage a of na and lineage b of na , respectively. the majority of lineages and sub-lineages were found to be host or geographic specific. this study provides not only a better understanding of influenza na evolution, but also a database of lineages and sub-lineages that can be used for early detection of novel genetic changes for improved influenza surveillance. although phylogenetic approaches are commonly used and often found to be powerful, how to accurately identify lineages or sub-lineages of a gene segment of the influenza a virus remains a challenging issue. in this study, we address this issue by analyzing hemagglutinin (ha) sequences using a combination of statistical and phylogenetic methods. following a hierarchical nomenclature system that uses a letter to represent a lineage and a digit for a sub-lineage, we identified distinct lineages and sub-lineages in all ha subtypes through large-scale analyses of influenza a hemagglutinin sequences. the majority of the lineages or sub-lineages were host or geographic specific or both. further analysis of other segments will allow us to construct a comprehensive database for influenza a lineages and genotypes, facilitating early detection of new viral strains and genome reassortments and hence improve influenza surveillance. identification of the genetic origin of influenza a viruses will facilitate understanding of the genomic dynamics, evolutionary pathway, and viral fitness of influenza a viruses. the exponential increases of influenza sequences have expanded the coverage of influenza genetic pool, thus potentially reducing the biases for influenza progenitor identification. however, these large amounts of data generate a great challenge in progenitor identification. clinical (nasopharyngeal swabs) and post-mortem materials (fragments of trachea, bronchi, lungs, spleen) were obtained from clinics and ⁄ or out-patients from st. petersburg and from base virological laboratories (bvls) of the research institute of influenza in different regions of the country, which cover approximately ⁄ of the territory of russia. the informed consent for the bio-materials collection and studies was obtained from research subjects or from their relatives in cases of post-mortem materials. isolation of viruses was carried out in the mdck cell culture (cdc, atlanta, ga, usa) and in -day-old chicken embryos (e). isolation was done according the standard internationally accepted methods. the reaction of hemagglutination (ha) and the inhibition of hemagglutination (hai) were performed according the who recommended standard method. for the identification of epidemic isolates, we used the hyperimmune diagnostic bovine or ovine antisera annually obtained from the who reference center (cdc). for a detailed antigenic analysis we used the hyperimmune rat antisera against epidemic and reference influenza strains during the period from july , up to april , , we have obtained swabs from clinics and out-patients in st. petersburg and swabs from the bvls. in this period, rather high incidence of lethality from pneumonia was observed, which developed on the background of the pandemic flu h n v. thus, we received from bvls postmortem materials from deceased patients which manifested pcr+ influenza h n v-specific rna. all materials were tested for a possibility of isolation of influenza virus h n v both in eggs and in mdck cells. pcr-negative materials were discarded. we isolated strains of pandemic influenza from the materials collected in st. petersburg and region, which comprised ae % of the total number of analyzed samples. at the same time, we did not isolate any other sub-types of influenza in the season - except the pandemic flu. from the swabs purchased from bvls, strains were isolated, which compose ae % of the pcr+ samples, and strains from the post-mortem materials ( ae % of the pcr+ samples).altogether in the season - , we isolated, retrieved, and analyzed in hai influenza strains. ae % of them were pandemic strains a(h n )v, and only ae % influenza b viruses. these data together with the epidemiologic data and the results of pcr-diagnostic provide evidence in favor of nearly mono-etiological character of epidemic season - in russia for pandemic influenza a(h n )v.though the isolation of pandemic viruses was fulfilled in two traditional model systems, in the case of pandemic virus, we could observe the tendency of preferential multiplication in embryos compared to mdck, especially in cases of post-mortem material for which chicken embryos are the preferential system of isolation.h n v viruses, which were isolated and passaged in mdck, even with significant ha titers, quickly lost their ha activity provided they were kept at + °c. moreover, some other tested cell lines proved to be practically nonsensitive to the pandemic viruses h n v. we used hai reaction for the typing and antigenic characterization of isolated viruses. in the course of isolation of viruses in the reported period, we produced rat polyclonal antisera to the strains a ⁄ california ⁄ ⁄ and a ⁄ st. petersburg ⁄ ⁄ (h n )v and the antisera to the strains a ⁄ new jersey ⁄ ⁄ -the virus isolated during the epidemic in the united states and also of the swine origin -and to the 'swine' strains a ⁄ sw ⁄ ⁄ and a ⁄ iowa ⁄ ⁄ . the hai results of representative strains are given in figure . table shows that the isolated strains were homogenous in their antigenic properties and interacted with the diagnostic antiserum cdc for a(h n )v and also with the antisera to the strains a ⁄ california ⁄ ⁄ and a ⁄ st. petersburg ⁄ ⁄ up to - ⁄ homologous titer. viruses that were isolated from post-mortem materials did not differ by their antigenic characteristics from those isolated from swabs of live patients. only two strains could be attributed to the drift-variants of the strain a ⁄ california ⁄ ⁄ because they reacted with the appropriate antiserum up to ⁄ homologous titer; these strains were a ⁄ pskov ⁄ ⁄ and a ⁄ belgorod ⁄ ⁄ . it is interesting that the isolated strains reacted with the antisera to the strains a ⁄ new jersey ⁄ ⁄ and a ⁄ sw ⁄ ⁄ to ⁄ - ⁄ , and some particular strains even to ⁄ homologous titer. it is even more interesting that some pandemic isolates reacted with the antiserum to the strain iowa isolated in up to ⁄ - ⁄ homologous titer. despite of the fact that since the outbreak of 'swine flu' in the usa in new jersey years had gone (and for the strain iowa this period is nearly years) the ha of these viruses and of the pandemic influenza share some common antigenic determinants as was shown in hai.one more interesting feature of a considerable part of isolated strains is their capability to react with high titers with normal equine serum heated to and to °c, while all the strains of swine origin isolated earlier were inhibitor-resistant ( figure ). russian isolates of divided, in this respect, in two clear and approximately equal in number groups: one of them is similar to the reference strain amino acid substitutions, among them more than were disclosed in antigenic sites, so the degree of similarity to this strain is %. a new site of glycosylation was also discovered in the position of ha. essential distinctions of the aminoacid sequence of ha and antigenic properties of the h n v strains as compared with actual circulating and vaccine strains is one of the factors that determine the pandemic potential of this new influenza virus.according to the literature, the mutation in the ha gene d g could cause a broadening of the spectrum of receptor specificity of influenza virus by the acquisition of the capacity to bind both the residues a( fi ) and a( fi ) of the sialic acid of cellular receptors. both types of receptors are present at the human respiratory tract, but in different parts of it, and they exist in different proportions. according to the data of the european center of disease control and prevention (ecdc), the varieties g of the h n v virus were isolated in countries from subjects deceased of influenza or who suffered a severe form of illness, as well as from those who sustained only a light course of influenza. concerning the strains isolated in rii, this mutation was discovered in nine cases: four were isolated from live patients and five from post-mortem materials. thus, there are no convincing data at present that could prove a causal relationship of the given substitution and the aggravation of a disease course. this is in accordance with previous observations. concerning the resistance of studied strains to the widely used antiviral preparations, it was shown that all tested strains possessed the substitution s n in the m protein that determine the resistance to adamantanes. there was no substitution in the position of neuraminidase (na), which determines the resistance to oseltamivir (h y). these substitutions are the characteristic indices of the eurasian lineage of swine influenza viruses. thus all studied russian h n v isolates were resistant to adamantanes (rimantadine) and sensitive to oseltamivir. respiratory clinical samples taken in and that tested positive by real time reverse transcription (rt)-pcr for seasonal influenza viruses (a and b) and pandemic h n respectively were assessed for other respiratory viruses using the resplex ii panel ver . system distributed by qiagen. results showed that co-infections with another respiratory viruses were relatively rare, with a small number of samples having another co-infecting virus present, very few samples having two other viruses detectable in their samples, and none with further viruses. this low number of co-infecting viruses and the ability of certain cell lines not to support infection with particular viruses may make primary isolation of influenza viruses in cell lines easier than might have been thought previously. cm is the second membrane protein of influenza c virus and is posttranslationally modified by phosphorylation, palmitoylation, n-glycosylation, and dimer ⁄ tetramer formation. in the present study, we generated rcm -c a, a recombinant influenza c virus lacking cm palmitoylation site, and examined viral growth and viral protein synthesis in the recombinant-infected cells. the rcm -c a virus grew less efficiently than did the wild-type virus. membrane flotation analysis of the infected cells revealed that less np was recovered in the plasma membrane fractions of the rcm -c a-infected cells than that in the wild-type virus-infected cells, suggesting that palmitoylation of cm is involved in the affinity of the ribonucleoprotein complex to the plasma membrane, leading to the efficient generation of infectious viruses. influenza c virus has seven single-stranded rna segments of negative polarity, encoding pb , pb , p , haemaggluti- both the a , linkage and its topology on target cells were critical for human adaptation of influenza a viruses. the binding preference of avian flu virus h n ha to the a , -linked sialylated glycans is considered the major factor that limited its efficient infection in human. currently, the switch in binding-specificity of human h n viruses from a , to a , -glycans did naturally occur, and limited humanto-human transmission was found. to monitor their potential adaptation in the human population, receptor-binding specificity surveillance was made in china. here, the binding specificity of human h n virus strains isolated from to was demonstrated. dual binding preference to a , and a , -glycans were found in a ⁄ guangdong ⁄ ⁄ and a ⁄ guangxi ⁄ ⁄ . furthermore, both of them showed a high affinity to the long-branched a , -glycans, which predominate on the upper respiratory epithelial in human. our data suggests that the existence of h n virus with binding specificity to humans should be of concern.introduction via envelope glycoprotein hemagglutinin (ha), influenza viruses bind to cell-surface glycosylated oligosaccharides terminated by sialic acids (sa) where their linkage is celland species-specific. differential receptor binding preference is a host barrier for influenza virus transmission. although most h n viruses have low affinity to neu aca , gal (human-type) receptor, recent findings suggested that the adaptation of h n virus to human by mutations in the receptor-binding site (rbs) do indeed happen and resulted in enhanced affinity to human-type receptor. [ ] [ ] [ ] in contrast to its putative precursor, a ⁄ gs ⁄ gd ⁄ ⁄ , diverse genotypes were presented in currently circulating h n virus, accelerating evolution and widespread occurrence. , to date, distinct phylogenetic clades ( - ) were identified based on h n ha, and the confirmed human infections were caused by clade , , ae , ae , ae , and . in china, human h n disease was mostly caused by clade ae ae , which was identified in isolates from confirmed patients from provinces since . clade and clade ae are responsible for the case in and , respectively. two current cases of and were due to clade ae ae . now information on receptor property has been documented in some h n viruses of clade , ae , and ae . [ ] [ ] [ ] little is known about h n virus of clade ae ae , particularly from human.recently, a , -specific sialidase-treated red blood cell (rbc) agglutination assay was developed and used for receptor specificity screening of h n virus. , the a , or a , -binding preference can be distinguished by the change of hemagglutination titer reacted with rbcs and enzymatic rbcs. since fine receptor specificity existed in h n viruses, , the glycan array including sulfated-, fucosylated-, linear sialosides, di-sialosides, or direct binding assay with synthetic polyacrylamide (paa)-based sialylglycopolymers was also recommended for the receptor-specificity surveillance on h n viruses. furthermore, the long-branched a , sialylated glycans were currently identified to predominate on the upper respiratory epithelial in human and the recognition of this topology, ¢sln-ln is the key determinant for the human-adaptation of influenza a virus. here, we analyzed the receptor-binding specificity of human h n viruses isolated in china from to . since , a total of h n infection cases were confirmed in china from provinces. the pharyngeal swabs and lower airway aspirations from the patients were collected within days after disease onset, maintained in viral-transport medium, and tested within hours.options for the control of influenza vii key: cord- -e s el s authors: parashar, umesh d; anderson, larry j title: severe acute respiratory syndrome: review and lessons of the outbreak date: - - journal: int j epidemiol doi: . /ije/dyh sha: doc_id: cord_uid: e s el s nan , the chinese ministry of health notified the world health organization (who) of an outbreak of atypical pneumonia that likely emerged in guandong province, china, in november . during late february to early march , clusters of atypical pneumonia were recognized in vietnam, hong kong, canada, and singapore. [ ] [ ] [ ] [ ] [ ] epidemiological investigations revealed that the index patients for each of these clusters had stayed on the ninth floor of a hotel in hong kong on - february (figure ). further investigation indicated that the likely source of the outbreak was a physician from guandong province (case a) who stayed on the same hotel floor on february. this physician had cared for patients affected by the respiratory disease outbreak and he had been symptomatic with a febrile, respiratory illness since february. this dramatic chain of transmission brought to the world's attention this new respiratory disease, called severe acute respiratory syndrome (sars), and clearly illustrated the potential for sars to spread extensively from a single infected person and to rapidly disseminate globally through air travel. the who issued an historic global alert and, together with its international partners, initiated a rapid and intense response to this global public health emergency. the response led within weeks to the identification of the aetiological agent, sars-associated coronavirus (sars-cov), [ ] [ ] [ ] [ ] and to a series of decisive and effective containment efforts that interrupted the last chain of human transmission in less than months. in this article, we review what has been learned about the aetiological agent and its pathogenesis and pathology, clinical manifestations, epidemiology, and diagnosis plus strategies for control of sars. sars-cov is an enveloped, positive-stranded, rna virus in the coronaviridae family ( figure ). coronaviruses are associated with a variety of enteric and respiratory disease syndromes in several animal species. the two recognized human coronaviruses other than sars-cov, oc , and e, have definitively been associated only with upper respiratory illness. sars-cov was first cultured in vero e cells from autopsy tissue, bronchoalveolar lavage, and nasal swab samples obtained from patients hospitalized in hong kong, canada, germany, and singapore, with identification by electron microscopy and complete genomic sequencing. the aetiological role of sars-cov was confirmed by the replication of an illness similar to that seen among humans in experimentally infected cynomolgus macaques, followed by re-isolation of the virus and detection of a specific immune response in the infected macaques. , the genomic sequence of sars-cov is quite distinct from that of other human and animal coronaviruses, , suggesting that the virus has likely circulated in its natural reservoir for a considerable period of time. the search for the origins of sars-cov and its potential reservoir(s) is ongoing. as many as % of the early sars cases in guandong occurred among people who were involved in animal trade or in food preparation, and people involved in animal trade in guandong were more likely to have antibodies to sars-cov than those who did not trade animals or general population controls. in addition, a coronavirus with % homology with human sars-cov isolates was recovered from civet cats and a racoon dog sold live for food in markets in guangdong. collectively, these observations support the hypothesis that sars-cov was first transmitted from wild animals used for food to humans, with subsequent personto-person transmission. experimental studies have shown that ferrets and domestic cats are also susceptible to infection by sars-cov and that they can efficiently transmit the virus to previously uninfected animals that are housed with them. further clues to the animal reservoir for sars-cov might be provided by studies of wild and domesticated animals from animal markets in guandong and the genomic sequence analysis of any viral isolates obtained from these species as well as from human patients. studies have also demonstrated the presence of antibody to sars-cov or a sars-cov-like virus in a small proportion of healthy adults in hong kong who had sera banked in may , at least years prior to the sars outbreak. this finding suggests that sars may have been transmitted periodically in the past from animals to humans and the virus may have evolved and adapted to human infection and transmission or that chance events resulting in efficient transmission led to the outbreak in . angiotensin-converting enzyme (ace ) was recently identified as a functional sars-cov receptor, and ace is efficiently expressed in lung, heart, kidney, and gastrointestinal tissue in humans. sars-cov has been isolated in cell culture in autopsy specimens from lung, intestinal, and kidney tissue of patients who died of sars. , sars-cov rna can also be detected by reverse transcription-polymerase chain reaction (rt-pcr) assays in the plasma and serum of more than % of patients during the first week of illness. pathological findings in the lungs of sars patients during the first days of illness include pneumocyte proliferation and desquamation, hyaline membrane formation, mixed inflammatory infiltrate, and intra-alveolar oedema. , increased numbers of interstitial and alveolar macrophages, with focal haemophagocytosis in interstitial macrophages, have also been described. in cases of longer duration, diffuse alveolar damage, squamous metaplasia, and multinucleated giant cells, of macrophage origin, are observed. biopsy and autopsy specimens from the colon and terminal ileum of sars patients show relatively normal architecture with no evidence of villous atrophy or inflammatory infiltrates. no distinct histopathological changes have been described in other tissues. the role of cytokines and immunopathogenic mechanisms in sars are being investigated. lymphopaenia is common among patients with sars. while cd t lymphocytes counts are reduced in nearly all sars patients, reductions in circulating levels of cd t lymphocytes, b lymphocytes, and natural killer cells are also common. , cd and cd lymphocyte counts fall early in the course of illness, and low cd and cd levels have been associated with more severe illness. the presence of lymphopaenia and pathological manifestations of diffuse alveolar damage, destruction of the white pulp of the spleen, and haemophagocytosis suggest that proinflammatory cytokines released by stimulated alveolar macrophages may have a major role in the pathogenesis of sars. death from sars usually occurs late in the course of illness (Ͼ week after onset) and has been attributed to adult respiratory distress syndrome, multiorgan failure, thromboembolic complications, secondary infections, and septic shock. coinfection with human metapneumovirus has been reported among patients with laboratory-confirmed sars; however, the role of co-infection in amplifying the pathogenicity of sars-cov is unknown. sars-cov disease has a median incubation period of approximately - days; most patients become ill within - days after exposure. the most common initial symptom is fever, often accompanied by headache, myalgias, malaise, chills, and rigor. respiratory symptoms typically do not begin until - days after onset of fever, but may be present at onset in up to one-third of patients. lower respiratory tract symptoms are common and typically include a non-productive cough with later onset of dyspnoea. upper respiratory symptoms such as rhinorrhoea and sore throat are seen in less than % of patients. diarrhoea has been reported at presentation in approximately % of patients, although this symptom was observed in as many as % of all patients affected by an outbreak at an apartment complex in hong kong that is believed to have resulted from fecal-oral/respiratory transmission of sars-cov. respiratory signs such as rales and rhonchi are present in less than one-third of cases, and their severity often does not correlate with the findings seen on chest radiographs. elderly patients and those with underlying chronic illnesses such as renal failure sometimes present with atypical symptoms, including the absence of fever. in general, sars appears to be milder in children. , haematological abnormalities include lymphopaenia ( - % of patients), thrombocytopaenia ( - %), prolongation of the activated partial thromboplastin time ( - %), and elevated levels of lactate dehydrogenase ( - %), alanine or aspartate aminotransferases ( - %), and creatinine phosphokinase ( - %). none of these laboratory findings can reliably discriminate between sars-cov disease and other atypical pneumonias. chest radiographs may be normal in up to % of patients who are evaluated early in illness, and high-resolution chest computed tomography scans can detect abnormalities in up to two-thirds of patients with normal chest x-rays. [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] nearly everyone with sars-cov disease develops radiographic evidence of pneumonia by illness day - . the radiographic abnormalities typically begin as isolated, focal, ground glass opacities predominately in a peripheral location, often in the lower lobes, and progress over several days to focal, multifocal, or diffuse consolidation involving additional lobes or both lungs; mediastinal lymphadenopathy, cavitation, atelectasis, and pleural effusions are uncommon. some - % of patients with sars-cov disease require mechanical ventilation, and about half of these people die despite ventilation therapy. severity of illness and risk of death from sars increases with advancing age and in the presence of certain underlying medical conditions, particularly diabetes mellitus. the overall case-fatality rate of approximately % can increase to Ͼ % in people older than age . during the global epidemic, cases of probable sars with ( . %) deaths were reported in countries. the countries with the greatest number of reported cases included mainland china (n = ), hong kong special administrative region (n = ), taiwan (n = ), singapore (n = ), and canada (n = ). health care facilities were severely affected and transmission in hospitals was a major factor in the amplification of outbreaks. in addition to health care workers, who accounted for % of all cases globally, other patients on the same ward as sars patients and visitors to the hospital were affected. for example, of cases reported from april to june in toronto, canada, % occurred among health care workers, % resulted from exposure during hospitalization, and % occurred among hospital visitors. after health care facilities, households of sars patients were the second most common setting of sars-cov transmission. surveys in hong kong and singapore indicated that - % of people in the households of sars patients may have been secondarily infected. , the risk of transmission was greatest among those involved in direct patient care or other close contact with the patient. transmission to casual and social contacts appears to be uncommon, but secondary cases have been documented after exposures in the workplace and on airplanes and other conveyances. , the epidemiology of sars outbreaks suggests that sars-cov is transmitted primarily through droplets and close personal contact, a conclusion that is supported by the finding that surgical masks confer protection against infection. , studies documenting stability of the virus for days in the environment raise the possibility of fomite transmission, and in a few instances, possible transmission by small-particle aerosols cannot be excluded. in particular, aerosol-generating medical procedures (e.g. endotracheal intubation, bronchoscopy) may be associated with an increased risk of transmission in health care settings. [ ] [ ] [ ] [ ] given that profuse watery diarrhoea is seen in a significant proportion of patients and sars-cov can be shed in large quantities in stool, faeces remain a possible source of virus and fecal-oral or fecal-respiratory spread are the leading hypotheses for a large outbreak affecting more than people at an apartment complex in hong kong. mathematical modelling studies indicate that each sars case infects an average of two to four people. [ ] [ ] [ ] however, some sars patients are very efficient in transmitting sars-cov to susceptible people under certain circumstances, leading to socalled 'super-spreading events'. , [ ] [ ] [ ] [ ] super-spreading events have occurred in a number of settings, including the hotel in hong kong, from which the sars outbreak disseminated globally, and hospitals in many locations. the factors contributing to super-spreading events are not completely understood but may be related to the inherently greater infectiousness of some patients, alternative modes of transmission, or the exposure of large numbers of contacts in an environment conducive to transmission. asymptomatic sars-cov infections have been documented, but they appear to be uncommon and their epidemiological significance in disease transmission has not been established. the risk of transmission from patients appears to be greatest during the second week of illness, which correlates with the timing of peak viral load in respiratory secretions. the timing of peak infectiousness might also explain, in part, the predilection for sars-cov to spread in health care settings, as most patients seek medical care by the end of the first week of illness. although sars-cov rna can be detected in fecal specimens by rt-pcr for more than a month after the onset of illness, no transmission has been documented more than days after the resolution of fever. genome sequencing analyses indicate that sars-cov isolates from the outbreaks in hong kong, vietnam, singapore, toronto, and taiwan are closely related and match the viral isolate obtained from the ill physician from guandong province, supporting the epidemiological conclusion that each of these outbreaks was directly or indirectly linked to the ill physician. on the other hand, sars-cov isolates from guangdong province exhibit greater diversity and other viruses belonging to genetic lineages different from the global outbreak strain were introduced into hong kong prior to march , but these introductions did not lead to large outbreaks. these data raise the question of whether some viral strains may have an inherently greater epidemic potential; this hypothesis needs further evaluation. alternatively, differences in transmission unrelated to virus strain (i.e. super-spreading events) could explain the presence or absence of outbreaks associated with independent human infections. the clinical manifestations of sars-cov disease are not sufficiently distinct from those of other respiratory pathogens to permit a reliable differential diagnosis. however, a combination of clinical and epidemiological features can provide clues to the diagnosis of sars. with no documented person-to-person transmission of sars-cov worldwide, the predilection for sars-cov to cause unusual clusters of pneumonia in health care settings provides a means to focus on surveillance efforts. if the re-emergence of sars-cov is confirmed, then a history of exposure to known sars casepatients or sars-affected areas may be helpful in early recognition of patients. the laboratory diagnosis of sars-cov is based on either detection of viral rna in clinical specimens or the finding of antibodies directed against sars-cov in serum. viral isolation is not recommended for routine diagnosis because of its low sensitivity and the biosafety hazards it poses. available real-time rt-pcr assays for sars-cov are highly specific and can detect as few as - copies of viral rna in clinical specimens, but a low viral load in respiratory and fecal specimens during the first week of illness limits the clinical sensitivity and utility of these assays. limited data suggest that sars-cov rna can be detected in the serum of more than % of sars patients during the first week of illness. because of the potential for contamination, positive rt-pcr results should be confirmed by testing a second specimen in a reference laboratory. the identification of serological antibody to sars-cov remains the reference standard for confirmation of sars-cov infection. however, antibody is usually detectable only after the first week of illness and some patients may not mount an antibody response for up to - days after illness onset. it is important to note that neither a negative rt-pcr test nor a negative test of serum obtained Ͻ days after illness onset can reliably exclude infection with sars-cov. body fluids that should be submitted for testing from patients with suspected sars include respiratory tract secretions, serum, whole blood, and stool. lower respiratory tract specimens (e.g. sputum, bronchial alveolar lavage fluid) appear to have higher yield than upper respiratory tract specimens (e.g. nasal or pharyngeal aspirates or swabs). collection of multiple specimens of different types is likely to increase the overall diagnostic yield, and different specimens will have a greater diagnostic yield at different times in illness (table ) . sars-cov test results should always be considered in the context of clinical and epidemiological findings. in the setting of no sars human-to-human transmission worldwide, the positive predictive value of a sars-cov test is extremely low, and thus any positive laboratory result must be interpreted with extreme caution because of its implications for global public health. diagnostic assays for other respiratory pathogens may be helpful in differentiating sars-cov disease from other illnesses, but sars patients may be simultaneously infected with sars-cov and another respiratory pathogen. factors that should be considered in the evaluation of patients with dual infections include the strength of the epidemiological exposure criteria for sars-cov disease, the specificity of the alternate diagnostic test, and the compatibility of the clinical presentation and course of illness with the alternative diagnosis. in the absence of a vaccine, effective drugs, or natural immunity to sars-cov, the key to controlling sars is the classic public health control strategy of case identification and containment. these measures proved effective and were associated with cessation of transmission throughout the world by july . the key to containment efforts is a surveillance system that provides ready access to timely information on the number of new cases, the likely source of exposure for cases, the number of cases not previously identified as contacts, and the number of contacts with high-risk exposures to known cases (potential prospective cases). since sars anywhere has implications locally, nationally, and globally, it is essential that the health care and public health communities exchange information on individual sars cases and the status of sars transmission in the community and globally. once a potential case of sars is detected, appropriate infection control measures must be implemented immediately to prevent transmission. sars patients often require hospitalization because of the severity of their illness; those with less severe illness are sometimes hospitalized to ensure that strict isolation procedures are followed. in other settings, patients have been managed in residential settings after evaluation of their suitability for this purpose. because the possibility of airborne transmission cannot be excluded, patients who require hospitalization should preferably be admitted to an airborne infection isolation room or specially adapted sars unit or ward where they can be treated safely and appropriately. in some settings, a lack of isolation rooms and/or a need to concentrate infection control efforts and resources may lead to a strategy of grouping patients in individual rooms on the same floor, which proved effective in many settings in the outbreak. health care workers should strictly adhere to use of appropriate personal protective equipment, and the potential for transmission to other non-sars patients and hospital visitors should be minimized through administrative controls. contact tracing, the identification of people potentially exposed to a case of sars, is essential to prevent spread. this provides a means to focus control efforts on people who are at high risk of sars, to identify people early in the course of their illness, and to implement control measures before they can spread the virus to others. contact tracing, evaluation for illness, and monitoring should be an immediate high priority to maximize the chance to rapidly control an outbreak. during the outbreak, quarantine of exposed people was one of the contact management strategies used to prevent inadvertent sars-cov exposures by separating those exposed from the unexposed. this potentially decreased the interval between the onset of symptoms and the institution of control measures. other key components of an effective sars control strategy include the following: ( ) systems for rapid and frequent communication of crucial information about sars; ( ) education and training of public health and health care workers about the clinical and epidemiological aspects of sars, appropriate use and interpretation of laboratory tests, and best practices for effective use of infection control strategies; and ( ) efficient information technology systems that provide a means to link clinical, epidemiological, and laboratory data on sars cases and to disseminate this information locally, nationally, and globally, and systems that allow rapid identification, tracking, evaluation, and monitoring of contacts of sars cases. the emergence of sars-cov dramatically illustrates the potential for a new disease to suddenly appear and spread, leading to widespread health, social, and economic consequences. fortunately, the experience also demonstrates the power of traditional public health measures-including surveillance, infection control, isolation, and quarantine-to contain and control a sars outbreak. it is not possible to predict when and where sars-cov will reappear and whether it will cause similar outbreaks in the future. possible sources of virus for a re-emergence of sars-cov include its original animal reservoir, persistent infection in humans, or the laboratory. the recently detected sars-cov cases in china are hypothesized to represent animal-to-human transmission, , and each of the laboratory-acquired cases in singapore and taiwan highlight the need for stringent biosafety precautions. , to achieve the type of swift and decisive response that is required to control a sars outbreak, we must be prepared and have learned from the many lessons of the sars outbreak. preparation for a response to an outbreak of sars requires co-ordination and co-operation among public health, health care, and other emergency response entities at all levels of government. investments in sars preparedness are likely to yield additional dividends in preparedness to battle other emerging infectious diseases and other threats to public health. epidemiological and aetiological studies of patients with severe acute respiratory syndrome (sars) from guangdong in a major outbreak of severe acute respiratory syndrome in hong kong a cluster of cases of severe acute respiratory syndrome in hong kong identification of severe acute respiratory syndrome in canada clinical features and short-term outcomes of patients with sars in the greater toronto area severe acute respiratory syndrome-singapore world health organization. who issues a global alert about cases of atypical pneumonia [press release world health organization multicentre collaborative network for sars diagnosis. a multicentre collaboration to investigate the cause of severe acute respiratory syndrome coronavirus as a possible cause of severe acute respiratory syndrome identification of a novel coronavirus in patients with severe acute respiratory syndrome a novel coronavirus associated with severe acute respiratory syndrome update -taiwan, china: sars transmission interrupted in last outbreak area koch's postulates fulfilled for sars virus newly discovered coronavirus as the primary cause of severe acute respiratory syndrome the genome sequence of the sars-associated coronavirus characterization of a novel coronavirus associated with severe acute respiratory syndrome role of china in the quest to define and control severe acute respiratory syndrome prevalence of igg antibody to sars-associated coronavirus in animal traders-guangdong province isolation and characterization of viruses related to the sars coronavirus from animals in southern china sars virus infection of cats and ferrets sars-related virus predating sars outbreak, hong kong. emerg infect dis the chinese sars molecular epidemiology consortium. molecular evolution of the sars coronavirus during the course of the sars epidemic in china angiotensin-converting enzyme is a functional receptor for the sars coronavirus fatal severe acute respiratory syndrome is associated with multiorgan involvement by coronavirus (sars-cov) sars coronavirus-infected cells in lung detected by new in situ hybridization technique detection of sars coronavirus in plasma by real-time rt-pcr lung pathology of fatal severe acute respiratory syndrome lung pathology of severe acute respiratory syndrome (sars): a study of autopsy cases from singapore enteric involvement of severe acute respiratory syndrome-associated coronavirus infection expression of lymphocytes and lymphocyte subsets in patients with severe acute respiratory syndrome haematological manifestations in patients with severe acute respiratory syndrome: retrospective analysis human metapneumovirus detection in patients with severe acute respiratory syndrome clinical progression and viral load in a community outbreak of coronavirus-associated sars pneumonia: a prospective study atypical sars in geriatric patient. emerg infect dis [serial online children hospitalized with severe acute respiratory syndrome-related illness in toronto severe acute respiratory syndrome (sars) in children: epidemiology, presentation and management thin-section ct of severe acute respiratory syndrome: evaluation of patients exposed to or with the disease severe acute respiratory syndrome: radiographic appearances and pattern of progression in patients thin-section ct in patients with severe acute respiratory syndrome following hospital discharge: preliminary experience radiologic manifestations of severe acute respiratory syndrome sars: imaging of severe acute respiratory syndrome severe acute respiratory syndrome: radiographic and ct findings severe acute respiratory syndrome: radiographic review of probable cases in toronto imaging of severe acute respiratory syndrome in hong kong outcomes and prognostic factors in patients with severe acute respiratory syndrome in hong kong world health organization. cumulative number of reported probable cases of severe acute respiratory syndrome (sars) update: severe acute respiratory syndrome-toronto, canada secondary household transmission of sars probable secondary infections in households of sars patients in hong kong. emerg infect dis [serial online transmission of the severe acute respiratory syndrome on aircraft consensus document on the epidemiology of severe acute respiratory syndrome (sars) who/cds/csr/gar/ . . geneva: world health organization effectiveness of precautions against droplets and contact in prevention of nosocomial transmission of severe acute respiratory syndrome (sars) investigation of a nosocomial outbreak of severe acute respiratory syndrome (sars) in toronto, canada illness in intensive care staff after brief exposure to severe acute respiratory syndrome cluster of sars among medical students exposed to single patient, hong kong. emerg infect dis [serial online possible sars coronavirus transmission during cardiopulmonary resuscitation. emerg infect dis [serial online transmission dynamics and control of severe acute respiratory syndrome transmission dynamics of the etiological agent of sars in hong kong: impact of public health interventions modeling the sars epidemic emerg infect dis [serial online asymptomatic severe acute respiratory syndrome-associated coronavirus infection molecular epidemiology of the novel coronavirus that causes severe acute respiratory syndrome combining clinical and epidemiologic features for early recognition of sars. emerg infect dis [serial online sars international reference and verification laboratory network: policy and procedures in the inter-epidemic period update : review of probable and laboratory-confirmed sars cases in southern china new case of laboratory-confirmed sars in guangdong, china-update world health organization. severe acute respiratory syndrome (sars) in singapore world health organization. severe acute respiratory syndrome (sars) in taiwan, china key: cord- -jqqxqjzf authors: rui, m.; qi, d.; yong, l. title: a sparse gaussian network model for prediction the growth trend of covid- overseas import case: when can hong kong lift the international traffic blockad? date: - - journal: nan doi: . / . . . sha: doc_id: cord_uid: jqqxqjzf the covid- virus was first discovered from china. it has been widely spread internationally. currently, compare with the rising trend of the overall international epidemic situation, china's domestic epidemic situation has been contained and shows a steady and upward trend. in this situation, overseas imports have become the main channel for china to increase the number of infected people. therefore, how to track the spread channel of international epidemics and predict the growth of overseas case imports is become an open research question. this study proposes a gaussian sparse network model based on lasso and uses hong kong as an example. to explore the covid- virus from a network perspective and analyzes consecutive days of cov- data in countries and regions around the world. this article establishes an epidemic spread relationship network between hong kong and various countries and regions around the world and build a regression model based on network information to fit hong kong's cov- epidemic growth data. the results show that the regression model based on the relationship network can better fit the existing cumulative number growth curve. after combining the seijr model, we predict the future development trend of cumulative cases in hong kong (without blocking international traffic). based on the prediction results, we suggest that hong kong can lift the international traffic blockade from early to mid-june the covid- virus was found in wuhan, hubei province, china in december . according to the evidence of early transmission dynamics, interpersonal communication has occurred between close contacts since mid-december [ ] . in order to control the spread of infections, hubei and other provinces have adopted measures such as urban segregation and reducing inter-city mobility. through a large number of public health interventions, the local epidemic situation in various provinces and cities in china has been basically controlled. however, the international spread of the epidemic is inevitable. therefore, for areas where local transmission has been basically controlled, how to prevent overseas transmission has become the focus of current epidemic prevention work [ ] [ ] [ ] . this article takes hong kong as an example to discuss how to effectively predict the cumulative case growth curve of regions with overseas imports as the main growth mode. as an important international transportation hub, the migration of a large number of international passengers has had an important impact on the spread of the epidemic in hong kong. foreigners entering all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted may , . . https://doi.org/ . / . . . doi: medrxiv preprint through international transportation channels such as aircraft shipping are the main way of increasing cases in the region. in order to reduce the possible transmission risk, from : on march , , hong kong announced that non-hong kong people are prohibited from entering hong kong airport. however, as an international financial and transportation center, hong kong will cause a lot of losses every day due to the international traffic blockade. therefore, it is of great significance to predict the possible cumulative case growth rate of hong kong under the premise of incomplete blockade, and to further determine the possible date of unblocking in hong kong. however, the transmission rate in the traditional sir/seir model is a constant value. however in practical problems, the transmission rate is constantly changing. for example, the growth rate of overseas imported cases is affected by changes in the international epidemic, etc. in this situation, it is difficult to use traditional infectious disease models to predict the future growth trend of hong kong [ , ] . therefore, finding a new model to solve this problem has become an open research question. in our research, we used days of real-time infection data from countries and regions around the world. establish a case transmission relationship network between hong kong and other parts of the world through the sparse gaussian network model based on lasso. the results show that the correlation coefficient between the epidemic trend in hong kong and several outbreak centers abroad is extremely high. at the same time, we can use the cumulative case growth data in areas with high correlation to hong kong in the network to establish a regression model to fit the cumulative case growth data in hong kong. after further combining the seijr model to predict case growth data of target areas (related to hong kong). we can predict the number of covid- cases in hong kong without blocking traffic. our findings can help hong kong adjust public interventions, estimate the time for lifting the blockade, and provide effective evidence to avoid serious outbreaks and economic losses. all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the real epidemic data set used in this article mainly comes from the website:https://github.com/blankerl/dxy-covid- -data，including the cumulative number of confirmed cases and cumulative number of cured cases from january to april , . this article uses a gaussian graph model based on lasso to construct an international epidemic spread network. we use a neighborhood selection strategy to solve the covariance selection problem. the specific model is as follows: consider n-dimensional multivariate normally distributed random variables = ( ,⋯⋯ ) ∼ ,∑ .this includes gaussian linear models, for example, is the response variable, neighborhood selection can be used as a standard regression problem. it can be effectively solved by lasso [ ] , as shown in this article. all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted may , . . https://doi.org/ . / . . . doi: medrxiv preprint for sparse high-dimensional graphs, the consistency of the proposed neighborhood selection will be shown, the number of variables may increase with any power of the number of observations (high-dimensional), and the number of neighbors of any variable is the slowest than the number of observations (sparseness). neighborhood selection. as we all know, lasso [ ] proposed by tibshirani et. al., in the context of wavelet regression [ ] , it is called basic pursuit and has simplicity [ ] .when the forecast has all remaining variables ; Γ\ \ . the estimated value of the disappeared lasso coefficient asymptotically identifies the neighborhood of node a in the graph, as shown below. let × dimensional matrix contain independent observations. therefore, for all Γ , column corresponds to a vector of independent observations. let • , • be the usual inner product on rn, and • is the corresponding norm [ ] . lasso estimates the formula of in , as formula ( ): is the norm of the coefficient vector. it is recommended to normalize all variables to a common empirical variance in the above formula. the solution of the above formula is not necessarily unique. however, if the uniqueness fails, the solution set is still convex, and all of our results on the neighborhood apply to any solution of the above formula. other regression estimates based on the norm have been proposed, where is usually in the range [ , ] (reference [ ] ). a value of = will result in a ridge estimate and = t corresponds to the traditional model selection. as we all know, only when , the estimated value has a parsimony property (some components happen to be zero), for ≥ , the optimization problem in the above formula is only convex. therefore, the minimization of empirical risk constrained by occupies unique position, due to = is the only value of , the variable selection is performed on this value, and the optimization problem is still convex, so it is feasible for high-dimensional problems. the neighborhood estimate (parameterized by λ) is defined by the nonzero coefficient estimate of penalty regression as formula ( ): all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. therefore, each choice of penalty parameter λ specifies the estimate of the neighborhood of node Γ , and the rest is to choose the appropriate penalty parameter. a larger penalty value tends to reduce the size of the estimated set, and if the value of λ decreases, usually more variables are included in the estimated value. predict oracle solutions. a seemingly useful choice of penalty parameters is (unavailable) to predict the oracle value as formula ( ): expectation is understood to be about the new , which has nothing to do with the samples that estimate , . the prediction penalty minimizes the prediction risk in all lasso estimates. the h m estimate is obtained by selecting m for cross-validation. shao [ ] showed that for a -penalty return. the cross-validation selection of penalty parameters is consistent with the model selection of the verification set size under certain conditions. predict that the oracle solution will not lead to consistent model selection for lasso. in ∑ = ∑ = . for some t < < and all . under the prediction oracle penalty, the probability of choosing the wrong neighborhood for node converges to as formula ( ): from the proof of proposition , it can be concluded that many noise variables are included in the prediction of the neighborhood of the oracle solution. in fact, for a fixed number of variables, the possibility of including noise variables in prediction predictions will not even disappear gradually. if the selected penalty is greater than the predicted optimal value, then lasso can be used for consistent neighborhood selection. all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. does not need to set the learning rate. however, there is an additional regularization parameter c than the perceptron. similar to most regression algorithms, the purpose of passive aggressive algorithms is to use training samples to learn relevant parameters to minimize the value of the loss function [ ] . in the learning of training samples (‫,ݔ‬ǡ) one by one, passive aggressive algorithms uses stochastic gradient algorithms to update parameters. first, the gradient ∇ of the loss j associated with the newly input training samples (‫,ݔ‬ǡ) is obtained. then update the parameter in the direction of gradient descent as formula ( ): in the probability gradient descent method, when the gradient descent is too large, the learning results tend to be unstable; when the gradient descent is too small, it will make the convergence rate slower. if researchers can reasonably choose the loss function. it can make the gradient drop to the bottom of the valley quickly. therefore, a penalty coefficient is generally introduced. that is, when deviating from the current solution , make appropriate adjustments to the amount of gradient descent. therefore, we can get formula ( ): λ is a positive scalar. such a learning method can effectively suppress the gradient descent. this algorithms is called passive aggressive algorithms. the specific algorithms of passive aggressive algorithms are: . select the initial value, t . using the newly input training samples (x, y), formula is updated for the parameter as formula ( ). . repeat the second step until convergence all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted may , . . https://doi.org/ . / . . . doi: medrxiv preprint in the regression problem, the function j (θ) has two different ways: using h݉ and h݉. as shown in formula ( - ): this article uses two regularizes to establish regression models respectively and uses data from countries and regions related to hong kong to fit hong kong's cov- cumulative cases data. after establishing regression models using known data. we found that most areas related to hong kong are still in the outbreak period of local transmission. in this situation, we can use the traditional infectious disease model to predict the growth trend of cases in these areas, thereby further predicting the possible growth trend of hong kong (without international traffic blockade). therefore, this article first uses the seijr model to predict the growth curve of the number of local diagnoses in countries and regions related to hong kong. finally, through these data, we can fit and predict the future growth trend of hong kong. the classic seir model divides the crowd into s (susceptible), i (infected), e (exposed) and r (recovered) [ ] . the model also assumes that all individuals in the population have an organic infection rate [ , ] . when the infected individual recovers, antibodies will be produced, that is, the recovered population r will not be infected again. in this study, the population was classified as susceptible s, latent e, infectious i, diagnosed j, recovered r, and respectively representing two populations with different susceptibility among susceptible populations, the infection risk of is low, risk probability value is p, the probability of asymptomatic latent persons being infectious is q, the probability of latent persons turning into infected persons is k, the isolation rate is l, the confirmed rate of infectious persons is α, the infectious person 's the recovery rate γ , the fatality rate of the infectious person δ, the recovery rate of the diagnosed person γ , the mortality rate δ[ ]. the transmission rate β is defined as the average number of infections caused by a person who is all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted may , . . https://doi.org/ . / . . . doi: medrxiv preprint susceptible to contact with class i per unit time. based on the above parameters, the model is established as follows as formula ( - ): in as shown in figure all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted may , . . https://doi.org/ . / . . . doi: medrxiv preprint the results are encouraging, from table , we find that the united states, hubei, china, iran, italy and other countries are hub nodes in the network. these countries have the most relations with other countries, which means that these countries are the main sources of international communication. this result is consistent with existing general knowledge. next, we extracted the subnets of countries and regions related to hong kong. as shown in figure ,we found that countries and regions are connected to hong kong. in addition to the hub nodes of the network. we also found south korea, russia and other countries that have close contacts with hong kong. we hope that the use of data from these countries and regions that are closely related to hong kong can help us fit the existing cumulative case growth data in hong kong and predict future trends. we have found that in areas related to hong kong, except for a few areas such as hubei in china, other areas are at the peak of local transmission. this situation means that researchers can use traditional infectious disease models to predict epidemic trends in these areas, which is also the basis for this article to use the sejir model. after getting the hong kong relationship subnet. we used passive aggressive algorithm based on and norm to establish regression models respectively. the experimental results are shown in figure . as shown in table - , the passive aggressive algorithm can fit the existing growth curve well, and the error of the -fold cross-validation is only - . . among them, passive aggressive algorithm_l has a better realization, and the minimum error is only . . the explained_variance and r indicators of both models are . , and mean_absolute_error is lower than . , shows an extremely high degree of fit to existing growth data. this result shows that we can use the data based on the relation network to fit the existing case growth situation in hong kong. this means that we can use countries related to hong kong to predict the future case growth curve of hong kong (unblocked traffic). all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted may , . . https://doi.org/ . / . . . doi: medrxiv preprint finally, we used the sejir model to simulate the cumulative case growth data of countries and regions related to hong kong. the parameters used in this article are shown in table , where beta is a floating value, which is adjusted according to the specific conditions of each country. since this article can collect real data from other countries from april - , this article first uses real data to predict the growth curve of hong kong's epidemic without blocking international traffic, the purpose is to evaluate the necessity of traffic blockade. as shown in at present, researchers have done a lot of work to predict the trend of local transmission of cov- . however, in many countries and regions, the growth pattern of outbreaks is dominated by overseas imports. existing research is difficult to predict effectively. therefore, we take hong kong as an example, the purpose is to propose an infectious disease model that predicts the growth trend of imported cases abroad. in this article, first, we proposed the sparse network model based on lasso, by analyzing the data matrix of real case statistics and drawing the cov- epidemic international network. from this all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. this article still has some shortcomings. for example, we assume that international tourists in hong kong will be quarantined and all infected persons will be diagnosed. however, some asymptomatic infected persons may still be missed, causing local transmission in hong kong. therefore, in the next step we plan to count the asymptomatic infection rate in hong kong and further improve the model in this article. no potential conflict of interest was reported by the author(s). all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted may , . . https://doi.org/ . / . . . doi: medrxiv preprint (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted may , . . https://doi.org/ . / . . . doi: medrxiv preprint figure fitting curve using passive aggressive algorithm based on and figure comparison between the predicted growth curve and the true growth curve without hindering international flows all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted may , . . https://doi.org/ . / . . . doi: medrxiv preprint predicting the cumulative number of cases for the covid- epidemic in china from early data the effect of travel restrictions on the spread of the novel coronavirus (covid- ) outbreak preparedness and vulnerability of african countries against importations of covid- : a modelling study covid- and italy: what next? the lancet estimation of the transmission risk of the -ncov and its implication for public health interventions gibbs and markov properties of graphs regression shrinkage and selection via the lasso: a retrospective asymptotics for lasso-type estimators pattern recognition and machine learning a statistical view of some chemometrics regression tools linear model selection by cross-validation online passive-aggressive algorithms global stability for the seir model in epidemiology statistical inference in a stochastic epidemic seir model with control intervention: ebola as a case study how will country-based mitigation measures influence the course of the covid- epidemic? the lancet all rights reserved. no reuse allowed without permission.(which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity.the copyright holder for this preprint this version posted may , . . https://doi.org/ . / . . . doi: medrxiv preprint all rights reserved. no reuse allowed without permission.(which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity.the copyright holder for this preprint this version posted may , . . https://doi.org/ . / . . . doi: medrxiv preprint all rights reserved. no reuse allowed without permission.(which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity.the copyright holder for this preprint this version posted may , . . https://doi.org/ . / . . . doi: medrxiv preprint key: cord- -lps qbxy authors: wong, j. s. w.; lee, j. k. f. title: the common missed handwashing instances and areas after years of hand-hygiene education date: - - journal: j environ public health doi: . / / sha: doc_id: cord_uid: lps qbxy the outbreak of severe acute respiratory syndrome (sars) claimed the lives of hong kong people in . since then, the hong kong government has been promoting the benefits of proper hand hygiene. there are few studies that explore the general quality of handwashing and the hand-hygiene practices of the public of hong kong; given this, the aim of this study is to explore this neglected topic. this study is a quantitative study that was conducted in january . the results show that the majority of participants only wash their hands after using the toilet ( %) or handling vomitus or faecal matter ( %). the mean duration of handwashing was . seconds (sd = . ). the areas of the hand most neglected during handwashing were the fingertips ( . %), medial area ( . %), and back of the hand ( %). a multiple logistic regression shows that participants who have reached third-level education or higher often tend to be more hand hygienic than those who have not reached third-level education (p ≤ . , b = . ). thus, participants aged and above tend to neglect more areas of the hand than those aged below (p= . , b = . ). in , hong kong was profoundly affected by an unknown communicable disease entitled "severe acute respiratory syndrome" (sars). e outbreak originated in a hospital and then spread to the wider community. e disease took the lives of hong kong citizens and people worldwide. in total, there were , known cases [ ] . given the seriousness of this outbreak, the promotion of the world health organization (who) guidelines and implementation of the "save lives: clean your hands" campaign became imperative. furthermore, in , the hong kong government established the centre for health protection (chp), a similar entity as the us's centers for disease control and prevention (cdc). e chp aims to effectively prevent and control diseases in hong kong, in collaboration with both national and international stakeholders. since the beginning of chp, the agency has devised numerous guidelines and publications for health workers and the general public in order to prevent the spread of communicable diseases and promote healthy living. following the sars outbreak in hong kong, proper hand hygiene has been widely promoted in multiple contexts, focusing on the instances when hands should be washed as well as the duration and technique of handwashing. e worldwide public health agencies have asserted that proper hand hygiene can control the spread of communicable diseases from the common cold to the life-threatening severe acute respiratory syndrome, as well as fight against the rise in antibiotic resistance. systematic reviews also show that insufficient washing of hands increases food-borne illness outbreaks and diarrheal diseases [ , ] . however, there are few studies that evaluate the compliance of hong kong people in this area or the effectiveness of their handwashing after years of health education on this topic. us, these are the main topics of interest for this study. the effectiveness of handwashing and alcohol-based hand sanitizers. e majority of handwashing and hygiene studies typically focused on healthcare providers and students, while few studies targeted the general public. e common areas of focus for these studies included the length of time spent handwashing, missed areas, common situations where handwashing was warranted, compliance with guidelines, and the relationship between demographic data and hand cleanliness. for instance, in the us, monk-tuner et al. reported that only % of their participants washed their hands for seconds or longer. drankiewicz and dundes observed in their study that only % of participating university students washed their hands for seconds or more [ ] . shanks and peteroy-kelly found that the average time university students spent washing their hands was a mere . seconds [ ] . a observational study conducted by michigan state university researchers also revealed that, among , people, the average washing times for men and women are . and . seconds, respectively, even though the cdc has been advocating the proper method for handwashing since [ ] . in turkey, ergin et al. reported that % of university students washed their hands just times per day. ey found that the main reason for students not washing their hands on a more regular basis was due to the belief that there was no need to do so. ey also found that female participants scored significantly higher in knowledge, skills, and practices of hand hygiene [ ] . in greece, mentziou et al. found that handrails and desks were the most frequently touched objects in universities, and the majority of university students performed handwashing after using the toilet and on returning home from university [ ] . in kenya, curtis et al. also found that handwashing after using the toilet was the most common instance of hand hygiene [ , ] . also, previous studies have identified that gender, age, employment status, and educational level are the factors that affect an individual's hand-hygiene practices. in the us, anderson et al., berry et al., edwards et al., and vanyolos et al. found that female participants washed their hands significantly more than male participants; in korea, park et al. also found this to be true [ ] [ ] [ ] [ ] . in the us, duggan et al. found that there was a reciprocal relationship between professional education and handwashing compliance [ ] . burnett found that an increase in age was linked to improved perceptions of hand-hygiene practices [ ] . lau et al. found that factors such as age, employment status, and perceived local outbreaks of sars were related to adopting good handhygiene practices for the protection of oneself and others [ ] . in contrast, pan et al. found that the number of areas of the hands that were neglected during handwashing had no correlation with the demographic data (gender, age, or profession) of participants; they also found no significant relationship between the duration of handwashing and the number of missed areas [ ] . some studies have revealed that exposure to proper hand-hygiene practices through mass media and the availability of handwashing facilities affect general handwashing practice [ , , ] . regarding the effectiveness of handwashing, szilágyi et al. and vanyolos et al. used fluorescent hand gel with ultraviolet (uv) light to assess the nursing and medical students' quality of handwashing [ , ] . e results showed that women wash their hands better than men, with nurses displaying the best handwashing practices. when comparing different age groups, participants aged - performed the best overall. e most common missed areas were the fingernails and wrists [ ] . a similar procedure using visual assessment was carried out by kampf et al., and the results showed that the palms and fingertips were usually quite thoroughly cleaned [ ] . in another study, kampf et al. used gel containing uv-sensitive dye [ ] . participants were asked to apply this gel to their hands and then wash them under running water. a graphical assessment technique was then used to assess the missed areas by evaluating the absence of the uv dye. e tools used in this study make reference to the above-mentioned literature. in hong kong, the chp advocates proper handwashing practice to the public aligned with the cdc in the united states, the national health service (nhs) in the united kingdom, the public health agency of canada, and the global handwashing partnership which includes washing one's hands with water and soap before and after at least eight specific situations; the process comprises six steps over seven areas of both hands for no less than seconds [ ] . in , the chp conducted a handhygiene survey. e results revealed that although hong kong people had a good understanding of hand hygiene, % of them reported that they did not wash their hands after using the toilet, and less than a third washed their hands after touching public equipment or installations. recently, lee et al. developed an observational checklist in order to assess foreign domestic workers' handwashing practices in hong kong [ ] . on average, they correctly performed out of the necessary handwashing steps. none of the participants rubbed their hands for seconds or more, and none of the participants rubbed all areas of their hands. moreover, a study was also conducted in a local hospital in relation to the compliance of healthcare professionals with the who's "my moments for hand hygiene" guidelines. e frequency of hand-hygiene practices was measured, but the quality of the practices was not evaluated. of the , situations in which hand hygiene should have been practiced in a unit with healthcare professionals, including nurses, physiotherapists, and healthcare assistants, the compliance rate was . %. lower rates of compliance were noted from : p.m. to : p.m. ( . %, % ci: . - . ), as well as among nurses who shared their badges with others ( . %, % ci: . - . ) [ ] . among the above-mentioned local studies, none of them was able to unveil the overall effectiveness of handwashing, and a comprehensive and in-depth exploration of hand-hygiene practices among hong kong people is neglected [ ] . erefore, this study was designed to fill this gap, and the following research questions were developed: ( ) what are the most common instances of handwashing among hong kong adults? ( ) how long do hong kong adults spend washing their hands? ( ) what areas are most commonly missed in handwashing? ( ) how many of the participants have received proper hand-hygiene information, and what are the common information resources? ( ) what are the differences between independent variables, common missed areas, and handwashing instances? ( ) what is the relationship between independent variables, common missed areas, and handwashing instances? is study used a cross-sectional survey with convenience sampling, and behavioural observations were conducted from january to march in . before conducting this study, ethical approval was obtained from the research ethics committee of a local higher-education institute in hong kong. e ethical committee reference number is nur/src/ / . given that the target population was hong kong adults and that public handwashing facilities were required, this study was conducted in several public barbecue sites in three different territories of hong kong (i.e., hong kong island, kowloon, and the new territories) in order to broaden the scope of this study. barbeque sites were chosen as areas to recruit participants because spacious handwashing facilities with touchless faucets and sinks were provided in an outdoor washing area. e participants were the visitors to the barbecue sites whose age ≥ , mentally sound hong kong residents, and those who were able to communicate with cantonese as cantonese is the mother tongue of hong kong people. participants who had experience working in healthcare settings and those with artificial nails, irremovable hand accessories, or a disability in both hands were excluded from this study. a survey was carried out by face-to-face interviews at the barbecue sites. e participants were required to report their demographic information, instances of handwashing, and their sources of handwashing information. . . procedure. first, information sheets were given to the participants. after obtaining informed consent from them, the participants were asked to rub glo germ gel in their hands. after the rater confirmed that both hands were fully covered by the gel, the participants were asked to wash their hands under running water in a way that was typical for them. when the participants were washing their hands, the rater stood far behind them and recorded the time it took them to complete the process. after the participants had washed their hands, a portable, rechargeable black box with watts of uv light was used to assess the residual fluorescent stains on the hands of the participants. e rater then recorded the results. machine (ibm) statistical product and service solutions (spss) for windows version . (ibm corp, ) was used for data analysis. e situations in which participants would commonly wash their hands, demographic data, and the duration of handwashing were analyzed by using descriptive statistics of frequency count, mean, and standard deviation. to compare the continuous data between the missed areas and variables in demographic data, independent t-test and one-way anova were used. linear and multiple logistic regressions were used to examine the relationship between variables in demographic data, duration of handwashing, and coverage of missed areas during handwashing. variables were presented as regression coefficients. e odds ratio was adjusted with corresponding % confidence intervals and p values. e statistical significance of p < . was taken into account. all statistical tests were two-tailed. eventually, ( males and females) valid data were collected from the barbeque sites in three main regions of hong kong, comprising ( %) participants from hong kong island, ( %) from kowloon, and ( %) from the new territories. e ratio of the number of participants in these three geographical areas was similar to the total population distribution of hong kong. e characteristics of the samples are shown in table . e leaflet devised by the chp advises hong kong people to wash their hands in at least different instances. ey are as follows: ( ) after handling vomitus or faecal matter, ( ) after using the toilet, ( ) before and after visiting hospitals or residential care homes or caring for the sick, ( ) after contact with animals or pets, ( ) before eating or handling food, ( ) after coughing or sneezing, ( ) after touching public installations or equipment, and ( ) before touching eyes, nose, and mouth. among the participants of this study, half ( . %) washed their hands in of the instances and only participants ( . %) washed their hands in all instances. e results showed that more than half of the participants washed their hands after handling vomitus or faecal matter ( . %), after using the toilet ( . %), before and after visiting a hospital or a residential care home or caring for the sick ( . %), after having contact with animals or pets ( . %), and before eating or handling food ( . %). in contrast, less than half of the participants washed their hands after coughing or sneezing ( . %), after touching public installations or equipment ( . %), and before touching their eyes, nose, and mouth ( . %) (figure ). using an independent t-test and an analysis of variance (anova) to compare the demographic data with handwashing instances, the results showed that the mean handwashing instances of participants with third-level education or above were significantly higher than those of participants who had primary-and secondary-level education only (p ≤ . ). among the participants, ( . %) received proper hand-hygiene information. given that this was an open-ended question, participants could list more than one resource. us, resources were reported. after grouping and categorising the resources, the result was revealed that the participants obtained information from the media ( %) and from schools ( %); relatively less information was obtained from hospitals ( %) and the workplace ( %). in addition, nearly two-thirds of the youngest age group obtained information from both schools and the media. however, only % of the oldest age group received that same information. moreover, the instances of handwashing of those participants who received informed hand-hygiene information were significantly higher than those of participants who did not (p ≤ . ). us, the mean of the total missed areas was significantly higher in participants who did not receive information about proper hand hygiene than those who received it (p � . ). on average, the participants took . seconds (range � - , sd � . ) to wash their hands. e majority of participants ( . %) washed their hands for longer than seconds, as advocated. for each participant, a total of anatomical areas were evaluated. e results showed that the fingertips ( . %), medial area ( . %), and back of the hand ( %) were the most commonly missed areas in terms of washing. using an independent t-test and anova to compare the differences between the demographic data and missed areas, we found that unemployed participants had significantly more missed areas than the other participants; the unemployed missed certain areas, including the back of the fingers (p � . ), palms (p � . ), back of the hand (p � . ), and medial areas (p � . ) ( table ). fulltime university students also neglected the back of the fingers (p � . ). blue-collar workers had significantly more missed areas, with the medial areas (p � . ) and the lateral areas (p � . ) of the hands being neglected. moreover, the results showed that participants with thirdlevel education or above (m � . , sd � . ) had significantly (p � . ) fewer total missed areas than those with primary-and secondary-level education only (m � . , sd � . ). among the different age groups, the youngest age group performed significantly better than the older age groups over the front of the fingers (p � . ), the back of the fingers (p � . ), and the lateral side of the hand (p � . and . ). in terms of the total missed areas, the youngest age group missed significantly fewer areas than the oldest (p � . ). multiple logistic regression was used to examine the relationship between the demographic variables, total missed areas, and instances of handwashing. e results showed that age is the only significant predictor of the total missed areas. ose aged and above tended to have more missed areas than those aged or below (p � . , b � . , % ci � . - . ). considering the variables affecting the total number of instances of hand hygiene, the only significant predictor among the variables was the educational level of the participants. ose with only primary-and secondary-level education tended to have more missed hand-hygiene instance than those whose educational levels were above the third level (p � . , b � . , % ci � . - . ). although there is scant empirical evidence on the duration of handwashing for the general public, the key public health agencies around the world, such as cdc, nhs, public health agency of canada, and global handwashing partnership, adopt the who's guideline for the healthcare providers as well as for the community use. in our study, almost % of the participants completed their handwashing routine in seconds or more. is contrasts with the studies conducted in the united states by drankiewicz and dundes, shanks and peteroy-kelly, and borchgrevink et al. [ ] [ ] [ ] . in , the who designed a handwashing leaflet, making reference to taylor, who indicated that the fingertips, interdigital areas, thumbs, and wrists are the most commonly missed areas in handwashing [ ] . pan et al. also found that the tips of the nails and the fingertips had the largest amount of residual florescent stains left after handwashing among healthcare workers in taiwan [ ] . e commonly missed areas among medical students in the study conducted by vanyolos et al. was the first metacarpal, the proximal part of the palm (lateral), the distal phalanges, and the nail beds [ ] . in healthcare workers inŠkodová et al.'s study, the thumbs and fingertips were the most commonly missed areas [ , ] . in this study, the most frequently missed area was also the fingertips. however, the medial aspect and back of the hand were the second and third most missed areas, respectively. moreover, the interdigital area and the front and back of the fingers were the [ , , , [ ] [ ] [ ] [ ] ] . in this study, we found that participants with higher educational levels had fewer missed areas, and they performed handwashing on a more regular basis; this is in contrast to the findings of duggan et al. [ ] . however, curtis et al. in kenya found that participants who had higher levels of education and literacy had a greater frequency of handwashing [ ] . eir study also revealed that media exposure is an important determinant of the frequency of handwashing. in korea, park et al. reported that participants who received information about handwashing did wash their hands on a more frequent basis; this finding is in concordance with the finding presented in this study [ ] . furthermore, curtis et al. also reported that "after defecation," "before feeding a child," and "before handling food" were the most common situations in which participants washed their hands [ ] . similar results were also found by blanton et al. amongst caregivers in kenyan schools [ ] . is was also the case with ergin et al. in relation to turkish university students [ ] . is study elicited the same results: "after handling vomitus or faecal matter," "before and after caring for the sick," and "before eating or handling food" are common situations in which hong kong people wash their hands. in relation to the association between age and handhygiene practices, we found that as age increases, handwashing becomes more neglected. however, burnett highlighted that participants aged years and older had good perceptions of hand hygiene, while the age group with the poorest perceptions was those under years of age. [ ] e results of this study may be explained by the intense focus on hand-hygiene education in primary and/or secondary schools after the sars attack in but relatively less in the community. is study did have its limitations. one of these limitations is the potential unease felt by the participants that evolved by asking for ad hoc handwashing at the venue. erefore, the researcher did stand far behind the participants, and the participants were not informed that the time spent washing their hands was being recorded. given the researcher stayed far behind the participants, their compliance with the steps of handwashing could not be evaluated. besides, although the self-report survey is the fastest way to gather abundant data, this method cannot avoid social-desirability bias in which the participants wanted to "be good," even though the survey is anonymous. hence, these two unpreventable conditions may produce potential influences on the results. furthermore, since most people had barbeque at sunny weekends only, suitable weather and period were quite short which limited the sample size. e results provide insights that will be useful for public health and primary-care professionals when reviewing health-promotion strategies for proper hand hygiene. although the sample size of this study was not large, this study and pan et al.'s taiwanese study found that the fingertips are the most commonly neglected areas [ ] . given that taiwan and hong kong are located in the same region, it is worth investigating if similar results are found in other asian countries. us, the reinforcement of fingertip washing is necessary for future handwashing practices. in addition, hand-hygiene education in schools seems to be quite effective; however, hand-hygiene education within the community seems inadequate, particularly for older adults and less well-educated groups. according to the world bank in , the population density of hong kong increased from , people per square kilometre in to , in , and it ranks as the fourth highest one in the world. people live more closely together than before, and population will increase in the future. since the outbreak of seasonal influenza and handfoot-mouth disease has been attacking hong kong frequently in recent years, the high population density of hong kong may exacerbate the risk of contracting communicable diseases through common contact surfaces such as door knobs, elevator buttons, handrails of escalators, and public transport. in addition to the effects of globalisation, other developed countries or cities with high population density may also be facing similar challenges. erefore, the public health and primary-care professionals may consider reviewing the protocol for proper hand hygiene and strategy of education and promotion and examine its effectiveness. all the quantitative data used to support the findings of this study are available from the corresponding author upon request. e authors declare that there are no conflicts of interest with respect to the research, authorship, and publication of this article. summary of probable sars cases with onset of illness from systematic review: hygiene and health: systematic review of handwashing practices worldwide and update of health effects effect of washing hands with soap on diarrhoea risk in the community: a systematic review handwashing among female college students research article: analysis of antimicrobial resistance in bacteria found at various sites on surfaces in an urban university hand washing practices in a college town environment evaluation of students' social hand washing knowledge, practices, and skills in a university setting evaluation of hand hygiene in groups of students in greece planned, motivated and habitual hygiene behaviour: an eleven country review evaluation of the role of school children in the promotion of point-of-use water treatment and handwashing in schools and households-nyanza province, western kenya predictors of hand-washing behavior usage of ultraviolet test method for monitoring the efficacy of surgical hand rub technique among medical students examining hand-washing rates and durations in public restrooms gender and ethnic differences in hand hygiene practices among college students inverse correlation between level of professional education and rate of handwashing compliance in a teaching hospital perceptions, attitudes, and behavior towards patient hand hygiene anticipated and current preventive behaviors in response to an anticipated human-to-human h n epidemic in the hong kong chinese general population assessing the thoroughness of hand hygiene: "seeing is believing a large-scale assessment of hand hygiene quality and the effectiveness of the "who -steps influence of rub-in technique on required application time and hand coverage in hygienic hand disinfection less and less-influence of volume on hand coverage and bactericidal efficacy in hand disinfection centre for health protection, perform hand hygiene properly, centre for health protection what is the hand washing performance in foreign domestic helpers in hong kong? introduction of an electronic monitoring system for monitoring compliance with moments and of the who "my moments for hand hygiene" methodology centre for health protection, chp survey shows personal hygiene not fully practised by public, centre for health protection an evaluation of handwashing techniques- hand hygiene technique quality evaluation in nursing and medicine students of two academic courses hand hygiene assessment in the workplace using a uv lamp graphical assessment technique (gat)-an objective, comprehensive and comparative hand hygiene quantification tool