cord-000562-ocp6yodg	2011	This study evaluates the timeliness of flight-contact tracing (CT) as performed following national and international CT requests addressed to the Center of Infectious Disease Control (CIb/RIVM), and implemented by the Municipal Health Services of Schiphol Airport. In this study, we assess the time delay in contact tracing of flight passengers for influenza A/H1N1 2009 as performed in the Netherlands during the initial phase of the pandemic. For each contact investigation performed in the period April 29th until June 22nd 2009, the following data were collected: flight arrival date, first day of illness of index patient, date of laboratory diagnosis, date of contact tracing request and the date passenger lists were obtained and contact details were completed (''contacts details identified''). Our study among 17 contact investigations showed an average total delay of 3,9 days between flight arrival and identification of contacts by passenger list, which is too late for effective PEP, and late for alerting on first symptoms of disease.
cord-001071-bjx5td52	2013	The number and duration of contacts varied between mornings, afternoons and nights, and contact matrices describing the mixing patterns between HCW and patients were built for each time period. The collected data can provide information on important aspects that impact the spreading patterns of infectious diseases, such as the strong heterogeneity of contact numbers and durations across individuals, the variability in the number of contacts during a day, and the fraction of repeated contacts across days. In particular, wearable sensors based on active Radio-Frequency IDentification (RFID) technology have been used to measure face-to-face proximity relations between individuals with a high spatio-temporal resolution in various contexts [17] that include social gatherings [18, 19] , schools [20, 21] and hospitals [22, 23] . In this paper we report on the use of wearable proximity sensors [17] to measure the numbers and durations of contacts between individuals in an acute care geriatric unit of a university hospital.
cord-007367-e31zhty6	2015	We estimate, using an agent-based model, the effect of network position of different hospital worker groups on the spread of infectious diseases in a hospital. Following the theoretical discussion, we use our newly collected data on healthcare worker and patient contacts to model the spread of an infectious disease in a hospital setting. The model allows us to identify the healthcare worker groups that would be expected to play the largest role in the spread of infectious diseases, in terms of network position, in this hospital setting. Because of these difficulties we use a simulation approach to help us measure the average and marginal effects of individuals belonging to different worker groups in our hospital contact data. We discuss the data and use agent-based models to identify the healthcare workers whose position in the hospital contact network has the potential to create large numbers of infections in the hospital.
cord-010310-jqh75340	2018	Furthermore, the transmission networks of infectious diseases established using contact tracking technology can aid in the visualization of actual virus transmission paths, which enables simulations and predictions of the transmission process, assessment of the outbreak trend, and further development and deployment of more effective prevention and control strategies. Tracking the contact interactions of individuals can effectively restore the ''''invisible'''' virus transmission paths, quickly locate and isolate high-risk individuals who were in contact with infected persons, and can aid in quantitative analysis of the transmission paths, processes, and trends of the infectious diseases, all leading to the development of corresponding effective epidemic control strategies. With the aim to collect dynamic, complete, and accurate individual contact information, some researchers began to use mobile phone, wireless sensors, RFID, and GPS devices to track individual contact behaviors. Although detailed individual contact information can be collected through non-automatic methods, e.g., offline and online questionnaire, and automatic methods, e.g., mobile phone, wearable wireless sensors, RFID, and GPS devices.
cord-017531-fm8gl5b3	2018	All transport of infectious patients from the place of arrival to the hospital should take place in ambulances using the same infection control regime as for the individual infectious disease (contact infection, airborne infection, strict isolation); see isolation regimes; Chaps. • Ambulance staff and other personnel use the contact and airborne infection regime when picking up and transporting a patient. Short-time airborne isolation of exposed cases until the infection state is clarified/effect of antibacterial therapy 82.5.6 Anthrax After Staying in Turkey, Sick on the Plane Home 82.5.6.1 Patient: Strict Isolation-Air Pressure Isolate with Pressure [21, 22] Example: Two out of six people who have been on family visits in Turkey for a week, on farms with goats and skin production, are acutely ill on the plane home with cough, shortness of breath and fever. Less severe disease: isolation of index case and close contacts • Registering: All exposed persons are registered (name, address, telephone number) and followed up.
cord-027598-76656pok	2019	title: A Smartphone Magnetometer-Based Diagnostic Test for Automatic Contact Tracing in Infectious Disease Epidemics This paper investigates how good a diagnostic test it would be, by evaluating the discriminative and predictive power of the smartphone magnetometer-based contact detection in multiple measures. Unfortunately, they either provide position information too coarse to be used for infectious contact detection [11] (GPS, cellular/Wi-Fi fingerprinting), require the infrastructure nearby (cellular/Wi-Fi), cannot be used indoors (GPS), consumes too much power for extended monitoring use (GPS) [12] , or could compromise privacy by exposing the identity of the device and eventually its owner (Bluetooth beacons). When the disease control authority performs an epidemiological investigation, they can use the smartphone magnetometer traces of the person confirmed infected and of the one suspected of a contact with the infected, in a system depicted in Fig. 1 .
cord-029354-c8sbqiyy	2020	Contact tracing is a fundamental public health intervention, and a mainstay in efforts to control and contain severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for the COVID-19 pandemic. 1 Regions with the most successful containment to date have approached the pandemic with integrated measures that include cohesive leadership, effective communication, physical distancing, wearing of face coverings, improvements in the built environment, promotion of hand hygiene, and support for the staff, supplies, and systems needed to care for patients-with testing and contact tracing as cornerstones of the approach. Along with efforts to expand conventional contact tracing programmes, there has been an ongoing debate about the value of digital contact tracing, ranging from issues of privacy, questions about efficacy, lower user adoption rates, and concern from some public health experts that mobile apps might distract resources from the core work of conventional contact tracing.
cord-031175-4dm4asen	2020	Thus, for being required by both governments, Self-quarantine Safety Protection app of South Korea and Health Code app of China are representative technology for examining the relationship between the effectiveness of mandatory centralized contract tracing apps and user stress. Based on the coping theory (Beaudry and Pinsonneault 2005; Lazarus and Folkman 1984) , this study proposes a structural equation model that shows the relationships between contact tracing app users'' stress and how they accept such stress through a process called challenge appraisal. To test the research hypotheses derived from the proposed structural equation model, survey data were collected from the users of Health Code, which is the mandatory and centralized contact tracing app with the largest user base. Figure 1 shows the relationships among accuracy and privacy concerns as factors affecting stress, challenge appraisal, emotion-focused coping behavior, and infusion as a structural equations model.
cord-035285-dx5bbeqm	2020	This proximity data of all app users are used to build a temporal contact graph, where vertices are devices, and edges indicate proximity between devices for a certain time period and with a certain Bluetooth signal strength. The use of the GCG App within an institutional setting, with data collection and usage governed by the organization, may lead to higher adoption of the app and enhance its effectiveness in contact tracing. The use of GCG is strictly voluntary, and there is an additional consent required by a user who is infected with COVID-19 before their data can be used for contact tracing-this, despite their data already being available centrally in the backend. Besides tracking Bluetooth contact data, the GCG App offers several features to inform the users about COVID-19 and engage them in preventing its spread.
cord-102587-fugb778l	2020	The amount of data collected allows us generate fine-scale age-specific population contact matrices by context (home, work, school, other) and type (conversational or physical) of contact that took place. For directly transmitted respiratory pathogens such as influenza, measles and coronaviruses, social mixing patterns shape the risk of individual-level infection [6] and population-level transmission dynamics [29, 18] , as well as the effectiveness of control measures targeted at specific age groups [2] . A landmark dataset of self-reported contacts was the POLYMOD study [22] , which collected social mixing data for 7,290 participants across eight European countries. Here we present high resolution age-specific social mixing matrices based on data from over 40,000 participants, stratified by key characteristics such as contact type and setting. Except for physical contacts, using BBC mixing matrices generally leads to more transmission in adult age-groups (particularly in ages over 25) whereas with POLYMOD dataset school-children are largely responsible for transmission regardless of how we construct the overall matrix.
cord-122159-sp6o6h31	2020	By comparing the device users'' location trails or the anonymous ID tokens they have collected with those from people who have COVID-19, one can identify others who have been near the person who is infected; this facilitates contact tracing in a more accurate and timely manner than the traditional manual approach. • An authority (public health official, healthcare provider, government official) collects the location history from the person who is infected and makes it available to users of the app. For this reason, we are building not only a contact-tracing app, but also Safe Places, a web-based tool for public health officials working to contain the COVID-19 pandemic. • Fostering trust • Developing key partnerships, including with community officials who can help drive local support for the solution • Creating solutions that meet the needs of public health officials responding to the pandemic • Focusing on the needs of the users • Providing value to the user during a contact-tracing interview even if they choose not to download the app before they have been diagnosed with COVID-19
cord-125722-maclu8gh	2020	As a consequence tracing the contacts of people identified as carriers is essential for controlling the pandemic. • The Gesundheitsamt (trusted authority): it tests people for COVID-19 infection, it publishes an anonymized list of carriers and it facilitates the categorization of contacts. • Roaming users: their devices monitor contacts at regular intervals (30 second) and store the list of contacts my_ctc as well a a list with location and orientation information my_loc, their devices check whether there was a contact to an infected person (at least once per day), and provide support to the categorization of the contacts, potentially using location and orientation information. • Users tested positively: their devices provide their lists my_ctc as far back as their owner''s infection may have been contagious to the Gesundheitsamt, they go into treatment or at least quarantine, and cooperate in determining the category of contacts that they had.
cord-136138-baxmoutj	2020	An example includes Contact Tracing Applications -those focused on identifying individuals who are at risk for developing COVID-19 through exposure to a person later identified as having been infected with SARS-CoV-2. The United States Centers for Disease Control and Prevention (CDC) identifies two types of digital contact tracing solutions -one focused on streamlining the capture and management of data on cases and contacts, the other on using Bluetooth or GPS to track an individuals exposure to an infected person [14] . One key benefit of contact tracing that applies to both manual efforts and digital applications is the ability to identify people who are exposed to an infected individual to encourage testing and quarantine. 3) Identifying outbreak ''hot spots'': Contact tracing solutions that capture location details in association with infections and exposures may be useful in identifying areas where 1) infections are growing, 2) the number of cases exceed a threshold, or 3) congregations of large groups of people are enabling rapid transmission.
cord-137892-1mrsvg3b	2020	Our proximity-based privacy-preserving contact tracing (P$^3$CT) leverages the Bluetooth Low Energy (BLE) technology for reliable proximity sensing, and an ambient signature protocol for preserving identity. Proximity sensing exploits the received signal strength (RSS) to detect the user''s interaction and thus classifying them into lowor high-risk with respect to a patient diagnosed with an infectious disease. Rather than using the conventional two-way BLE communication channels (i.e., a secure channel for data exchange established through a series of pairing and handshaking processes), the smartwatch uses a non-connectable advertising channel, which was primarily used by beacon-based applications, to broadcast the packet. While it is relatively straightforward to develop such an application to the smartwatch for contact tracing purposes, it remains unclear how accurate is the proximity sensing information estimated through the RSS value and how the ambient signature information can help to prevent information leaks.
cord-141541-g5pt10yn	2020	Figure 3 presents the typical CTA use-case described by many authors, in which: (a) the primary CTA user and others install and register the app on their smartphones; (b) as they move around and come into close physical contact with each other, their smartphones identify other smartphones and a contact trace is recorded; (c) an upload of some information passes from the CTA on the users device, via their provider''s core network (cellular or ISP); (d) from their provider, via the internet, to the HA servers; and (e) alerts and updates can also be sent from the HA server to individuals, or every user. Some variation is observed in the literature claiming to present privacy-preserving methods regarding: (i) the type of information passed from the CTA to the health authority server; and (ii) whether the data passes directly to the HA server or, as with the Singapore (TraceTogether), Australian (COVIDSafe) and proposed Apple/Google collaboration examples, into a thirdparty supplier''s international datacentre cloud network (i.e. Google, Apple or Amazon Web Services) before being received by the HA server (Maddocks, 2020) .
cord-169081-34z49l4b	2020	We propose the use of the Intel SGX trusted execution environment to build a privacy-preserving contact tracing backend. While the concept of a confidential computing backend proposed in this paper can be combined with any existing contact tracing smartphone application, we describe a full contact tracing system for demonstration purposes. This paper proposes an Intel SGX-based contact tracing system which provably cannot reveal any user''s location data while providing all benefits of a traditional contact tracing system. We focus on a confidential computing backend that can be used in combination with any of the currently existing contact tracing apps, requiring only minimal modifications. Current contact tracing apps typically rely on pushing the infected user''s location data to the entire system. We propose the use of Intel SGX to build a confidential computing backend that provably cannot reveal any user data and outline a complete contact tracing system for demonstration purposes.
cord-184854-2ledrw9j	2020	First we use theories of disease spreading on networks to look at the COVID-19 epidemic on the basis of individual contacts -these give rise to predictions which are often rather different from the homogeneous mixing approaches usually used. Newman [3] was the first to take into account that individuals needed to be resolved in terms of their ''degree distribution'', i.e. the number of people that they were in contact with, and his pioneering solutions to the disease propagation network have since been widely used [4] [5] [6] [7] for epidemics ranging from HIV to SARS-1. We demonstrate this here in the context of the city of Kolkata, which captures two aspects critical to our thesis -strong heterogeneity in terms of personal contact networks, as well as areas of great social deprivation, both of which, as will be seen, can lead to the rapid spread of epidemics.
cord-186764-qp4kq139	2020	In this paper, we outline general requirements and design principles of personal applications for epidemic containment running on common smartphones, and we present a tool, called ''diAry'' or ''digital Ariadne'', based on voluntary location and Bluetooth tracking on personal devices, supporting a distributed query system that enables fully anonymous, privacy-preserving contact tracing. The proposed system allows individuals to keep track of movements and contacts on their own private devices and to use local traces to select relevant notifications and alerts from health authorities, thus completely eschewing, by design, any risk of surveillance. The system is composed of: a mobile application, that is voluntarily installed by users on their smartphones, keeping track of their locations through the device''s GPS sensor and interactions with other users through Bluetooth radio beacons, a privacy-aware reward system, which incentivizes app usage while collecting anonymous usage information to feed an open data set, and a distributed query system that allows recognized public authorities to selectively and anonymously notify users about possible contagion sources.
cord-227492-st2ebdah	2020	• Users are individuals who have not been diagnosed with an infectious disease who seek to use a contact-tracing tool to better understand their exposure history and risk for disease. • Finally, we broadly speak of the government as the entity which makes location data public and informs those individuals who were likely in close contact with a diagnosed carrier, acknowledging that this responsibility is carried out by a different central actor in every continent, country or local region. The primary challenge for these technologies, as evident from their deployment in the COVID-19 crisis, remains securing the privacy of individuals, diagnosed carriers of a pathogen, and local businesses visited by diagnosed carriers, while still informing users of potential contacts. All containment strategies require analysis of diagnosed carrier location trails in order to identify other individuals at risk for infection.
cord-238444-v9gfh3m1	2020	Further, authorities use case quarantine strategy and manual second/third contact-tracing to contain the COVID-19 disease. In this paper, we developed a smartphone-based approach to automatically and widely trace the contacts for confirmed COVID-19 cases. From a technical standpoint, we summarise the most important contributions of this paper as follows: 1) We build a tracking model based on positional information of registered users to conduct contact-tracing of confirmed COVID-19 cases. The best thing to do seems to be let people go out for their business, but any body tests positive of COVID-19, we would be able, through proposed framework, to trace everybody in contact with the confirmed case and managing the lockdown and mass quarantine. In this study, K-means as an unsupervised machine learning algorithm is used to cluster the users'' positions information and predict that the area should be locked down or not based on same empirical thresholds.
cord-239315-dk2lwsrx	2020	This paper discusses the aspects of data reliability and user privacy for the emerging practice of mobile phone based contact tracing for the COVID-19 pandemic. Taking Norway as an example, a country with good tradition on respecting the privacy of its citizens and among the first to launch a COVID-19 contact tracing application, it is evident that no tender processes have been disclosed for awarding public funds to construct the application [53] , calls to open source the application in order to aid the review by security experts were denied [54] and that data that contain GPS, Bluetooth LE smartphone identifiers and health status were stored in private cloud vendors [55] with unclear status on whether the data can leave the Norwegian geographic border.
cord-248072-mlp51zgk	2020	Here, we perform a compare-and-contrast investigation between the equilibrium shapes of physical real-izations of tight elastic trefoil knots and those of ideal knots based on existing purely geometric models [21, 28] , both in open and closed configurations. We realize physical knots tied onto elastomeric rods (which are straight in their unstressed configuration) in experiment complemented with fully 3D elastic simulation using the finite element method (FEM); representative examples are provided in the experimental photographs and FEMsnapshots of Fig. 1 . Our measured curvature profiles for knotted elastic filaments, both in the closed and open trefoils, are qualitatively different from those predicted by the ideal geometric models. The excellent FEM-experimental agreement confirms the observed curvature profiles and enables us to extract and map the contact pressure distribution, thereby revealing significant rod constrictions at the entrance and exit of the tight open knot.
cord-251676-m8f6de33	2020	The tool analyses WiFi logs generated by the network, and specifically association and dissociation log messages for this device, at various access points on campus to reconstruct the location(building, room numbers) visited by the user. We note that such a client-centric approach requires a user to first download a mobile app before contact tracing data can be gathered-users who have not downloaded the app (or have opted in) are not visible to other phones that are actively listening for other devices in their proximity. As discussed below, this tier uses time-evolving graphs and efficient graph algorithms to efficiently intersect trajectories of a large number of devices (typically tens of thousands of users that may be present on a university campus) to produce its report. In this section, we describe case studies that evaluate the efficacy of our contact tracing tool and also present results on the efficiency of our graph algorithms and general limitations of our WiFi sensing approach.
cord-252903-pg0l92zb	2020	In this work, we use individual-based computational models to explore how digital exposure notifications can be used in conjunction with non-pharmaceutical interventions, such as traditional contact tracing and social distancing, to influence COVID-19 disease spread in a population. We use data at the county level to match the population, demographic, and occupational structure of the region, and calibrate the model with epidemiological data from Washington state and Google''s Community Mobility Reports for a time-varying infection rate ( 21 ) . Estimated total infected percentage, total deaths, and peak hospitalized under a 50% reopening scenario (an increase of 50% of the difference between pre-lockdown and post-lockdown network interactions) at various exposure notification adoption rates for King, Pierce, and Snohomish Counties, assuming no change to social distancing after the (t) β baseline and 15 manual contact tracers per 100k people.
cord-253345-r4dhmpq1	2020	This study proposes a non-contact sensing platform for the early diagnosis of COVID-19 symptoms and monitoring of the human activities and health during the isolation or quarantine period. (2) Propose a non-contact sensing platform for the early diagnosis of COVID-19 symptoms and the monitoring of human activities and health during the isolation or quarantine period. The rest of paper is organized as follows: Section 2 includes a literature review of the COVID-19 pandemic, the existing non-contact wireless sensing platforms and technology exploited, the monitoring of human activities and health, and the classification approach and accuracy achieved. A non-contact sensing method uses passive Doppler radar to capture human body movements to recognize respiration and other physical activities used for monitoring health. This research presents a comprehensive review on existing non-contact sensing of human activities and health monitoring that could be used for the development of a COVID-19 pandemic platform.
cord-255910-x807fpa7	2020	Contact surveys have been successfully used to quantify the reduction in the number of contacts associated with physical distancing measures in Shanghai and Wuhan, China, estimated at 88% and 86%, respectively (Zhang et al., 2020) , and in the UK (Jarvis et al., 2020) among the adult population, at 74%. By comparing the survey results before and after the implementation of these physical distancing measures, we could determine the impact on the number of contacts made in the community (i.e. outside the household), distinguishing between different age groups, genders, household sizes, days of the week and occupations. We analysed the baseline and physical distancing contact surveys by comparing the number of contacts in the community per participant stratified by several characteristics: age, gender, household size, day of the week, and occupation (as reported in the physical distancing survey, under the assumption that participants did not change occupation between the two surveys).
cord-255956-xfky1q4p	2020	This case report described the innovative design and build of an algorithm that integrated available data from separate hospital-based informatics systems that perform different daily functions to augment the contact tracing process of COVID-19 patients through identifying exposed neighboring patients and healthcare workers and assess their risk. This benchmark was in line with the US-CDC Interim guidance for Risk Assessment and Management of healthcare personnel with potential exposure to COVID-19 that stated that the care team contact tracing process should be completed within 24 hours of each case''s identification. [4] Data scientists, operations managers and clinical staff worked closely to integrate data available in the informatics systems with human-based interviews to improve the timeliness, comprehensiveness and efficiency of the contact tracing process. A data-mining algorithm was developed to integrate the available data from hospital-based informatics systems that perform various day-to-day functions to augment the contact tracing process of COVID-19 patients to identify exposed HCWs and neighboring patients.
cord-257801-rgzmpoxv	2020	Using detailed survey information on social encounters coupled to predictive models, we investigate the likely efficacy of the current UK definition of a close contact (within 2 meters for 15 minutes or more) and the distribution of secondary cases that may go untraced. Using detailed survey information on social encounters coupled to predictive models, we investigate the likely efficacy of the current UK definition of a close contact (within 2 meters for 15 minutes or more) and the distribution of secondary cases that may go untraced. Using preliminary estimates of COVID-19 transmission (average latent period 4 days, average effective infectious period 1.61 days, R 0 =3.11 and assuming a simple SEIR formulation (Read et al 2020)) we compute the distribution of epidemiological, social and contact tracing characteristics across the population.
cord-260039-k9rs3dql	2020	Aim: The aim of our study is to develop an ageand sex-specific model of COVID-19 transmission and to explore how contact changes effect COVID-19 infection and death rates. We develop an SEIRD-model that incorporates age-and sex-specific contacts, which shape transmission rates. The model can be used to develop scenarios which address the effects of age-and gender-specific changes in contacts due to the closing of schools, kindergarten and shops, or work in home office, as well as to explore the effect lifting of these measures. Incorporating age-and sex-specific contact rates in a COVID-19 compartment model permits exploration of the effects of changes in mitigation measures on the two genders. Our projections do not set out to forecast the actual number of COVID-19 infections in a time span of about two months, they rather assess the effect of increased contacts on the infection and mortality risks of the two genders and the various age groups.
cord-260797-tc3pueow	2020	In addition, we conduct extensive numerical simulations and conclude that heterogeneities in the contact network are important for a proper determination of the epidemic threshold, whereas the age-structure plays a bigger role beyond the onset of the outbreak. To bridge this gap, in this paper, we focus on analyzing the role that disease-independent heterogeneity in host contact rates plays in the spreading of epidemics in large populations under several scenarios, both numerically and analytically. A slightly better approximation is to divide the population into agegroups, given the demographic structure of the population, Fig 1B, and establish a different number of contacts between and within them (model M), which is the common approach currently used in the epidemic literature to model age-mixing patterns. Nevertheless, most network approaches focus only on determining the role that the difference in the number of contacts of the population has on the impact of disease dynamics but ignore other types of heterogeneities such as the age mixing patterns.
cord-263455-dquztf5l	2020	More chemoprophylaxis research is needed on: enhanced medication regimens; interventions in varying (epidemiological) settings, including focal mass drug administration (fMDA); specific approaches per contact type; combinations with screening variations and field-friendly rapid tests, if available in the future; community and health staff education; ongoing antibiotic resistance surveillance; and administering chemoprophylaxis with SDR-PEP prior to BCG administration. But, given the evidence for the effectiveness of SDR-PEP and the WHO guidelines for its use, the ethics of testing new post-exposure immunoprophylactic approaches for leprosy prevention without combining them with chemoprophylaxis in both the intervention and control group needs to be discussed. The combined effect of chemoprophylaxis with single dose rifampicin and immunoprophylaxis with BCG to prevent leprosy in contacts of newly diagnosed leprosy cases: a cluster randomized controlled trial (MALTALEP study)
cord-265891-jmpterrj	2020	Therefore, we will here implement a crude form of contact tracing where we (1) close the workplaces of people who are tested positive for the disease, (2) isolate their regular social contacts for a limited period, and (3) keep symptomatic individuals in quarantine until they recover. If 10% efficiency is possible, corresponding to detecting about a third of infectious cases, then peak height could be reduced by a factor of almost three with to a 60% drop, if the probability of infected people being tested is only 10% per day of illness. In Fig. 4 , we show two possible scenarios where testing and contact tracing is implemented after a 30-day lockdown with a 75% reduction of the work and social spheres. Using reasonable COVID-19 infection parameters we find that the 1STQ strategy can contribute to epidemic mitigation, in the sense that it can reduce the peak number of infected individuals by about a factor of two even with a realistic testing rate of 10% per day of illness.
cord-266878-z7qn80tw	2020	Regarding the use of contact lenses during this period of worldwide infection, mixed messages have emerged from various health sources, making it difficult for practitioners to provide absolute guidance to their patients. In addition, contact lens wearers may experience minor discomfort or irritation more frequently than spectacle wearers [14] , and this in turn increases the chance of the natural response to touch or rub eyes [15] . Practitioners of course, are responsible for impressing upon their patients the importance of good hygiene, but some additional precautions are needed during this time of pandemic. As patients may be unable to visit clinics or practices due to lockdown, it may be advisable for practitioners to contact the parents of all of their orthokeratology patients to alert them about this problem. The COVID-19 pandemic: Important considerations for contact lens practitioners
cord-268126-u9z1rir1	2020	The viability of CT apps as a useful pandemic-response measure, depends on a complex interplay of criteria, such as pragmatic assumptions about effectiveness, the likelihood of public health benefit, technological specifications, legal requirements etc. Nevertheless, risks that cannot be easily mitigated or avoided could still be acceptable, considering the severity of a pandemic situation, the importance of effective contact tracing to manage it, and the scope of established measures to stop virus transmission. Predicting future uptake of CT apps is difficult and depends on various factors, such as the penetration range rate of digital technologies in a society, the possibility to download and use the app on different types of smartphones, the credibility of institutions offering these solutions, and viable solutions for ethical concerns such as data security. Ethical considerations to guide the use of digital proximity tracking technologies for COVID-19 contact tracing.
cord-268463-ehp0q0ry	2007	We used stochastic simulation models to explore the effects of school closings, voluntary confinements of ill persons and their household contacts, and reductions in contacts among long-term care facility (LTCF) residents on pandemic-related illness and deaths. We used stochastic simulation models to explore the effects of school closings, voluntary confinements of ill persons and their household contacts, and reductions in contacts among long-term care facility (LTCF) residents on pandemic-related illness and deaths. By using these models to simulate an influenza pandemic, we estimated the effects of school closings, home confinement of ill persons (i.e., isolation) or their household contacts (i.e., quarantine), and reduction of contacts among residents of LTCFs on overall illness attack rates, hospitalization rates, and mortality rates. The interventions we examined in this simulation study were school closings, confinement of ill persons and their household contacts to their homes, and reduction in contact rates among residents of LTCFs. Interventions were implemented at the start of the outbreak.
cord-269850-5pidolqb	2020	1. We build a tracking model based on positional information of registered users to conduct contact-tracing of confirmed COVID-19 cases. The best thing to do seems to be let people go out for their business, but any body tests positive of COVID-19, we would be able, through proposed framework, to trace Fig. 3 A framework of contact-tracing using smartphone-based approach everybody in contact with the confirmed case and managing the lockdown and mass quarantine. In this study, k-means as an unsupervised machine learning algorithm is used to cluster the users'' positions information and predict that the area should be locked down or not based on the same empirical thresholds. This Fig. 6 The results of the prediction model for both scenarios is followed by send back notifications from the server to the users to notify them for the crowded area and controlling the spreading the coronavirus COVID-19.
cord-275253-6pwqa8zk	2020	The contrast in the degree of hypoxia ("silent hypoxia") and the pattern of infections in high-risk individuals who are unable to mount a stable immune response with modest symptoms explains the lethal spectrum of the novel coronavirus. In contrast, initial data on the role of ACE inhibitors augmenting the onset of severe forms of SARS-CoV-2 infection has discouraged their use and triggered the onset of severe cardiovascular events 7,8 . Covid19 in high risk individuals display severe respiratory symptoms, multi organ involvement and may require a long term rehabilitation as in a chronic disease. SARS-CoV-2 Isolation From Ocular Secretions of a Patient With COVID-19 in Italy With Prolonged Viral RNA Detection Cancer patients in SARS-CoV-2 infection: a nationwide analysis in China. The novel coronavirus disease (COVID-19) threat for patients with cardiovascular disease and cancer The oral surgery response to coronavirus disease (COVID-19)
cord-276763-x3dqi0ym	2013	During study observation periods, patients and staff were given RFID tags to wear. We report here the results of a year-long deployment of a RFID system covering all areas of an adult ED, describing the contacts between and among patients and staff. Furthermore, during the twelve-hour study periods, research assistants interacted with the system in real time to locate patients, staff, and equipment. Demographic and clinical characteristics of the patient admission data are shown in Table 1 , summarized for the population over the year, all patients in our 81 sampled shifts, and patient study participants only. Informal observations of interpersonal behavior made by research study staff suggest no change in number or duration of interpersonal contacts. In the study with the most comparable setting and methods, Gundlapalli and colleagues report data on contacts between 1261 patients and 87 staff in a pediatric hospital ED collected over the course of a randomly chosen month [20] .
cord-283093-9kz7387z	2020	In this study, we collect contact data from residents of informal settlements around Nairobi, Kenya, to assess if control measures have changed contact patterns, and estimate the impact of changes on the basic reproduction number (R(0)). Respondents were asked to report all direct physical and non-physical contacts made the previous day, alongside a questionnaire asking about the social and economic impact of COVID-19 and control measures. Although one social mixing study was conducted in Kilifi, a coastal area of Kenya [21] , outside of one study which collected data from a South African township [16] , no published contact data exist from informal settlements, which may be particularly vulnerable to COVID-19 due to high levels of population density, indoor crowding, and household sizes, alongside intergenerational mixing within the household.
cord-283467-bgxc3ti8	2020	title: Risk of SARS-CoV-2 infection among contacts of individuals with COVID-19 in Hangzhou, China Abstract Objectives This study determined the rate of secondary infection among contacts of individuals with confirmed COVID-19 in Hangzhou according to the type of contact, the intensity of the contact, and their relationship with the index patient. Methods The analysis used the data of 2,994 contacts of 144 individuals with confirmed SARS-CoV-2 infection. Centralized isolation and observation of close contacts of individuals with confirmed SARS-CoV-2 infection, in addition to population-based control measures, can reduce the risk of secondary infections and curb the spread of the infection. January 23, 2020, Zhejiang Province was among the first provinces to declare a major public health emergency and introduced ten policies including vigorously promoting public 2 awareness on epidemic prevention, restricting public gatherings, and taking measures to prevent hospital-acquired infections to prevent the transmission of SARS-CoV-2 infection.
cord-285105-72v6qufw	2020	In numbers, given that increases of 25% and 50% seem to be most likely given the data seen in Germany for the Easter weekend for example [2, 3] , our simulations show the following increases (compared to realistic reference run) for a temporary 25% surge in contact rate: the total cases grew by 215,880, the maximum of required hospitalizations over time increased to 63,063, and the total climb in fatalities was 8,844 accumulated over 90 days. In numbers, given that increases of 25% and 50% seem to be most likely given the data seen in Germany for the Easter weekend for example [2, 3] , our simulations show the following increases (compared to realistic reference run) for a temporary 25% surge in contact rate: the total cases grew by 215,880, the maximum of required hospitalizations over time increased to 63,063, and the total climb in fatalities was 8,844 accumulated over 90 days.
cord-286070-qwq46b8a	2004	The basic reproduction number R 0 describes the average number of secondary cases produced from contact with an infected person during the infectious period and without intervention. The effectiveness of the intervention therefore is determined by the probability of diagnosis per day of the infectious period, the time needed to identify contacts of the close contact and casual contact ring, the vaccination coverage in the close contact and the casual contact ring, and whether contacts are monitored. Our simulation results show that a smallpox epidemic starting from a small number of index cases can be contained by ring vaccination provided the intervention measures are very effective. Here the critical vaccination coverage in the casual contact ring is shown as a function of the basic reproduction number R 0 for different assumptions about the time it takes to diagnose infectious persons.
cord-295293-ickp2n47	2020	While the number of social contacts was substantially lower during the lockdown by more than 80% compared to the pre-pandemic period, we observed a more recent 121% increase during the post lockdown period showing an increased potential for COVID-19 spread. We repeatedly conducted an internet survey to follow up the impact of the local government interventions on social contact patterns in Luxembourg shortly after the lockdown was implemented due to the rapid local spread of the COVID-19. The average number of contacts reported by Luxembourg residents in a study before the pandemic was 17.5 [4] , suggesting that contacts during lockdown had decreased by 81.7%. Our study suggests that the strict physical distancing measures implemented in Luxembourg had a substantial and immediate impact on social mixing patterns resulting in a large reduction of the average number of contacts per day. In conclusion, our stud shows that physical distance measures resulted in significant reduction in social contacts and therefore decreased the spread of COVID-19 in Luxembourg.
cord-296487-m4xba78g	2019	If the response is delayed, or if the attack infects 10000 people, all available beds will be exceeded within 40 days, with corresponding surge requirements for clinical health care workers (HCWs). Specifically, we aimed to determine hospital bedcapacity for isolation, public health workforce capacity for contact tracing and health care worker (HCW) personal protective equipment (PPE) requirements under different attack scenarios. We estimated number of hospital beds needed to control the epidemic, PPE requirements for clinical HCWs and public health workers required for contact tracing, under different scenarios. The number of hospital beds needed for case isolation was then modelled under different scenarios based on variation of response time (T), the percentage of infected cases isolated each day and how many contacts were traced. The number of contacts needed to be traced and managed was estimated based on attack size, time to response (T) and the percentage of infected cases isolated each day.
cord-297612-swc2pitd	2020	title: Contact tracing for COVID-19: An opportunity to reduce health disparities and End the HIV/AIDS Epidemic in the US We argue that COVID-19 contact tracing may provide a unique opportunity to also conduct widespread HIV testing, among other health promotion activities. M a n u s c r i p t Massive SARS-CoV2 testing and contact tracing at a scale and speed never before seen have been proposed as critical components of a COVID-19 public health strategy that could, in theory, safely allow us to relax social distancing measures and begin to bring back the world we left behind before a cure or effective vaccine is delivered. Aside from the potentially profound health benefits of a combination implementation approach, pairing COVID-19 contact tracing with testing for HIV may serve to offset the immense costs of such an approach.
cord-306284-bj8u0dtk	2020	Similar to other countries in sub-Saharan Africa, the Kenyan government has imposed travel restrictions across counties, dusk-to-dawn curfew and school closure to ensure social distancing in the population and consequently slowed transmission of COVID-19. In this study, an age-structured SEIR mathematical model that examines the impact of NPIs in curbing COVID-19 severity and deaths in Kenya is developed, with the aim of achieving the following; (i) assessing the impact of reducing social contacts in different age-groups, (ii) examining the trend in infections during and after the NPIs, (iii) providing plausible period for lifting the NPIs. We postulate that this study can form a basis for policy formulation to enable Kenya delay the disease transmission and eventually flatten the epidemic curve. To show the impact of the highlighted measures in Kenya, we present results for daily and cumulative infections, severe and critical cases, deaths, as well as peak demand for hospital and ICU beds.
cord-306784-0cmekxs0	2020	title: Inflow restrictions can prevent epidemics when contact tracing efforts are effective but have limited capacity When a region tries to prevent an outbreak of an epidemic, two broad strategies are available: limiting the inflow of infected cases by using travel restrictions and quarantines or limiting the risk of local transmission from imported cases by using contact tracing and other community interventions. Regulating λ is particularly important when the contact tracing system is close to being overwhelmed by new cases arriving from elsewhere, in which case even moderate reductions in λ can strongly reduce the probability of an epidemic outbreak. By contrast, if contact tracing is effective but has limited capacity, there can still be an epidemic because of an overload of the system, and travel restrictions will affect the probability that such an overload happens.
cord-307342-3gkiukh4	2020	By late April 2020, public discourse in the U.S. had shifted toward the idea of using more targeted case-based mitigation tactics (e.g., contact tracing) to combat COVID-19 transmission while allowing for the safe "re-opening" of society, in an effort to reduce the social, economic, and political ramifications associated with stricter approaches. This viewpoint offers a discussion of why testing-tracing efforts failed to sufficiently mitigate COVID-19 across much of the nation, with the hope that such deliberation will help the U.S. public health community better plan for the future. Partly for this reason, our nation rushed to espouse the idea of targeted, case-based COVID-19 management [3] [4] [5] [6] , focusing on expanded testing and contact tracing, while disregarding several major obstacles that set us apart from countries that succeeded in mounting a timely, targeted response.
cord-314746-1o0rf0ii	2020	[Image: see text] In this article, we predict the folding initiation events of the ribose phosphatase domain of protein Nsp3 and the receptor binding domain of the spike protein from the severe acute respiratory syndrome (SARS) coronavirus-2. The identification of the primary contacts along the folding pathway of viral proteins constitutes an important result for at least two reasons: (a) the sequences of the specific segments involved in the primary contacts provide a template to specify candidate peptide drugs of inhibitory effect with the maximum possible contact affinity to compete with the natural folding mechanism; and (b) it provides insight for further investigation into the subsequent folding steps leading to a fully functional viral protein, potentially providing for additional FITRs. The fact that the primary contact is defined by the interaction between two well defined amino acid sequences suggests that a strategy to develop FITR-based therapeutic drugs could be one utilizing trial peptide drugs as suggested above.
cord-315466-74m7cur3	2020	We use an age-structured branching process model of the transmission of COVID-19 in different settings to estimate the potential of manual contact tracing and digital tracing systems to help control the epidemic. We investigate the effect of the uptake rate and proportion of contacts recorded by the digital system on key model outputs: the effective reproduction number, the mean outbreak size after 30 days, and the probability of elimination. While contact tracing alone is unlikely to contain the spread of COVID-19 Kucharski et al., 2020) , in countries like New Zealand where cases have been reduced to very low numbers (Cousins, 2020; Binny et al., 2020) , it may allow population-wide social distancing measures to be relaxed. Manual-only contact tracing (which corresponds to a digital uptake rate of = 0 in Fig. 3 ) with moderately (50%) effective quarantine of pre-symptomatic or subclinical individuals reduced to 1.55, the mean outbreak size to approximately 34 and increased the probability of extinction to 67%.
cord-319023-ucm8frol	2020	Model parameters included percentage population ordered to shelter-in-place, adoption rate of AACT, and percentage individuals who appropriately follow recommendations. Conclusion Wide adoption of digital contact tracing can mitigate infection spread similar to universal shelter-in-place, but with considerably fewer individuals isolated. Such Advanced Automated Contact Tracing (AACT) systems -which could infer exposure risk and propagate warnings to people at risk -may help curb disease spread by facilitating targeted self-isolation rather than universal mandates such as shelter-inplace. In AACT, an additional compartment Sq (Traced contacts that are exposed and under selfisolation) was used while for shelter-in-place, the compartment Q (Individuals isolated through universal enforcement measures) was used. The basic difference between the models is that isolation/quarantine is based solely on exposure history in AACT, while isolation orders apply to the entire population in universal shelter-in-place. Contact tracing can mitigate disease spread through a curated approach of identifying and isolating exposed individuals, as opposed to shelter-in-place orders.
cord-322806-g01wmmbx	2020	This paper presents a new method for accurately including the effects of Testing, contact-Tracing and Isolation (TTI) strategies in standard compartmental models. It provides a logical framework for understanding the propagation of an May 14, 2020 1/23 infectious disease through a population and allows different interventions to be explored, including testing and contact tracing of infected individuals as possible strategies to ease social distancing restrictions. In this paper we develop an extension to the classic Susceptible-Exposed-Infectious-Removed 1 (SEIR) model [16, 52, 53] simulated with ODEs to include testing, contacttracing, and isolation (TTI) strategies. To answer this we adapt the standard Susceptible-Exposed-Infectious-Removed (SEIR) compartmental model [16, 52] to incorporate contact tracing as well as testing and isolation of cohorts of people. Overlapping compartments represent model states that are not mutually exclusive, so that it is possible for an individual to belong in more than one of them e.g. be infected and contact-traced, or exposed and tested.
cord-323766-oyyj35bl	2020	In this paper, our aim is to set out a number of ethical considerations relevant to the use of mobile phone apps to enable rapid contact tracing. Any consideration of the ethical questions arising in the context of the COVID-19 pandemic has to place great importance on the moral significance of its international spread and the massive scale ii The effectiveness and reach of any implementation of the app in democratic societies will inevitably be affected by varying configurations of state-citizen relationships, as well as by the roles of civil society groups and non-governmental actors. In this paper, we have set out a number of pressing ethical questions raised by the proposed use of a mobile phone app, the collection of proximity data for the control of the COVID-19 pandemic, and the safe emergence of populations from government-imposed lockdowns.
cord-326579-vz8n2jsj	2020	Results Taking recent estimates for COVID-19 transmission we predict that under effective contact tracing less than 1 in 6 cases will generate any subsequent untraced infections, although this comes at a high logistical burden with an average of 36 individuals traced per case. Results Taking recent estimates for COVID-19 transmission we predict that under effective contact tracing less than 1 in 6 cases will generate any subsequent untraced infections, although this comes at a high logistical burden with an average of 36 individuals traced per case. Conclusions The current contact tracing strategy within the UK is likely to identify a sufficient proportion of infected individuals such that subsequent spread could be prevented, although the ultimate success will depend on the rapid detection of cases and isolation of contacts. 7 8 Here we leverage detailed social network data from the UK to model both transmission and the act of tracing, and identify the implications of early contact tracing for containment of a novel pathogen, using parameters for the novel coronavirus (COVID-19).
cord-332194-97tkyv3w	2020	We report the effectiveness of automated text messaging for active surveillance of asymptomatic close contacts of coronavirus disease (COVID-19) cases in the Cork/Kerry region of Ireland. As part of ongoing efforts to control the spread of infection, national and international guidance recommends active surveillance of asymptomatic close contacts of confirmed cases of COVID-19 [3] [4] [5] [6] [7] . However, evidence for the effectiveness of active surveillance systems among community-based close contacts of cases of COVID-19 has been limited to date. This study aimed to measure the effectiveness of an automated text-based active surveillance system which was used in Cork/ Kerry for the first 7 weeks of the COVID-19 response. In the first 7 weeks of the COVID-19 response in Cork/Kerry, 9.0% of close contacts who consented to participate in active surveillance were referred for testing and 2.6% tested positive for COVID-19. Automated active surveillance systems can thus facilitate early identification of symptomatic close contacts and positive cases of COVID-19.
cord-335518-ti889uye	2020	Modifiable factors that need particular attention in Spain include: handwashing for at least 20 seconds before lens handling, drying hands with single use paper towels, including a rub-and-rinse step for reusable lenses, lens case cleaning and renewal, avoidance of water exposure and when to cease lens wear during the pandemic. The aim of the current study was to evaluate by means of a survey the behaviours associated with contact lens wear (compliance with hand hygiene and adherence to contact lens wear and care recommendations) as well as to elucidate the best ways to support wearers during the COVID-19 pandemic in Spain. The questions related to lens care disinfection and lens case care were only displayed if the participant used reusable CLs. The final section focused on assessing concerns J o u r n a l P r e -p r o o f associated with contact lens wear and ways to best support wearers during the COVID-19
cord-337100-45qr0sak	2020	We built an expanded SIR model of COVID-19 epidemics that accounts for region-specific population densities, and we used it to test the impact of a contact-tracing app in a number of scenarios. Our results show that, in support of efficient isolation of symptomatic cases, app-mediated contact-tracing can improve containment and achieve successful epidemic mitigation even with relatively small fraction of the population using it, and, with increasing penetrance of its adoption, suppression. In this proof-of-concept study we built a comprehensive framework to model the COVID-19 epidemic, taking into account population density, the different contributions of symptomatic, pre-symptomatic and asymptomatic contagions, and we used it to test the efficacy of targeted intervention such as the aforementioned contact tracing app. We built an improved Susceptible-Infectious-Recovered (SIR) model with the aims of a) faithfully reproducing the dynamics of the SARS-CoV-2 epidemics, including the respective roles of asymptomatic infection and population density; b) test the effects of specific interventions, and specifically the use of phone apps for contact tracing.
cord-339405-sj7dd6jr	2020	To increase the evidence base supporting specific methods to measure social interaction, we compared data from self-reported contact surveys and wearable proximity sensors from a cohort of schoolchildren in the Pittsburgh metropolitan area. While proximity sensors and survey methods may not be interchangeable for capturing individual contacts, they can generate highly correlated data on age-specific mixing patterns relevant to the dynamics of respiratory virus transmission. Transmission models 187 When used in age-specific simulation, sensor-and survey-based mixing matrices produced 188 similar attack rates when adjusted by proportionate mixing expectations (Fig. 4) . We found that two common methods of collecting social contact data, self-274 reported surveys and proximity sensors, recorded qualitatively and quantitatively different 275 individual social mixing behaviour but could still generate similar aggregate age-specific social 276 contact patterns. . https://doi.org/10.1101/2020.07.12.20151696 doi: medRxiv preprint proximity sensors and self-reported surveys were likely to record contacts with different transmission potential, we fitted β for each set of parameters, including the age-specific mixing 18 (EP/N014499/1).
cord-339898-ptb6dst8	2020	10, 11 Several previous papers have considered the role of contact tracing for containment of COVID-19, [12] [13] [14] [15] but important questions remain about potential impact given uncertainty around the extent of presymptomatic and asymptomatic transmission of SARS-CoV-2 and the efficacy of voluntary isolation and quarantine. We defined scenarios by the fraction of symptomatic cases detected in the community (not linked to a tracked case), the fraction of contacts successfully traced, the isolation and quarantine efficacy among traced but undetected contacts, and whether testing was restricted to those with symptoms or includes all traced contacts ( Table 1) . Given the likely importance of levels of community testing as a prerequisite condition for contact tracing, we conducted a secondary analysis that quantified the combined benefit of scaling up both testing and contact tracing against a counterfactual in which detection of symptomatic cases remains constant at an assumed current fraction of 20%.
cord-340461-hebe5cjb	2020	Results We demonstrate that pre-collected social contact data, combined with incidence data and Google Community Mobility Reports, is able to provide a time-varying estimate of the reproduction number (R). In this study, we use social contact data [5] , including an additional targeted survey of children, to quantify the impact of re-opening schools on the reproduction number in the UK [9] . In this paper, we demonstrate that a combination of early death counts and social contact data provide sufficient information to estimate the potential impact of combinations of social distancing measures on the reproduction number for COVID-19 in the United Kingdom. Using metrics of adherence to social distancing measures, such as Google mobility or contemporary social contact surveys, it is possible to map the country''s progression across figure 1, and therefore estimate the effect of policy changes on the reproduction number and hence the population attributable fraction of cases due to multiple combined interventions [17] .
cord-341639-a8ig607t	2020	We considered scenarios that varied in: the number of initial cases; the basic reproduction number R0; the delay from symptom onset to isolation; the probability contacts were traced; the proportion of transmission that occurred before symptom onset, and the proportion of subclinical infections. For higher values of R0 and a large initial number of cases, contact tracing and isolation was only potentially feasible when less than 1% of transmission occurred before symptom onset. For example, the severe acute respiratory syndrome (SARS) outbreak that began in Southern China in 2003 was amenable to eventual control through tracing contacts of suspected cases and isolating confirmed cases because the majority of transmission occurred after symptom onset 7 . Figure 4 : The percentage of outbreaks controlled for the baseline scenario (black), and varied number of initial cases (A), time from onset to isolation (B), percentage of transmission before symptoms (C), and proportion of subclinical (asymptomatic) cases (D).
cord-346576-gtkx1r4a	2020	With a view to a gradual exit from lockdown, governments around the world are considering deploying contact-tracing apps to prevent or manage a second wave of coronavirus disease 2019 . 1 Many concerns arise over efficacy, privacy issues and data management by governments or health authorities. A simulation on one million people found that 80% of smartphone users in the UK (56% of the general population) would need to install a contact-tracing app to suppress the epidemic effectively. 2 In Singapore, the first country to deploy a voluntary contact-tracing app (TraceTogether), launched in March, only an estimated 17% of the population installed the app. On 19 April, a letter signed by nearly 300 academics warned that centralised systems can risk surveillance, and suggested that Apple and Google (currently working jointly in developing a contact-tracing app) should consider developing one which uses an opt-in and decentralised system.
cord-347217-zxsm18og	2020	• A non-partisan independent oversight committee with representatives from legal, health, machine-learning, and privacy experts should be established to oversee ongoing development of the application, its information ecosystem, and data governance • Importantly, public representatives must be included in this oversight committee Virtual data acquisition • No identifiable information regarding digital contact trails or personal health information that an individual enters on the application should be shared with other application users or public, private, and governmental agencies • Individual geolocation data should not be stored on a central server and should pass through a rigourous obfuscation protocol to reduce their information content to the bare minimum required for epidemiological and machine-learning modelling • Pseudonymised data should be used to inform machine-learning models, and only these data should be stored centrally on a protected server • Only non-identifiable aggregated data should be shared with public health institutions • The source code of the application and the algorithms used should be made accessible for public scrutiny • Personal identifiable information should be deleted from the device once the pandemic is over