key: cord-0931251-p8prbvch authors: Knudsen, Per Kristian; Lind, Andreas; Klundby, Ingvild; Dudman, Susanne title: The incidence of infectious diseases and viruses other than SARS-CoV-2 among hospitalised children in Oslo, Norway during the Covid-19 pandemic 2020-2021 date: 2021-12-22 journal: J Clin Virol Plus DOI: 10.1016/j.jcvp.2021.100060 sha: db6ce210e88ffa4eb06e85b980b59e6c7ae088aa doc_id: 931251 cord_uid: p8prbvch Background: Measures to reduce spread of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) during the Covid-19 pandemic 2020-2021 may impact other microbiological agents. We aimed to investigate the incidence of infectious diseases and the incidence of viruses other than SARS-CoV-2 among children at The Department of Paediatric and Adolescent Medicine, Oslo University Hospital, Norway during 2020-2021 compared to previous years. Methods: Data from April 1st 2020 – March 31st 2021 were compared to data from corresponding 12-months periods 2017-2020. ICD-10 infectious disease diagnoses were collected from the Hospital Diagnosis and Procedure Registry and results of virus PCR analyses of different specimens (mainly nasopharyngeal (NF) and faecal samples) were collected from the Laboratory System at the Department of Microbiology. Results: The number of hospital contacts with acute bronchiolitis, viral pneumonia, gastroenteritis and viral central nervous system infections were reduced by 90% (p<0.0001), 89% (p<0.0001), 74% (p<0.0001) and 78% (p<0.01), respectively. Respiratory syncytial virus (RSV), influenza virus A and B and Human metapneumovirus (HMPV) were almost completely absent during the pandemic period. The proportions of rhinovirus positive NF samples were 31.7% vs. 34.9% (p<0.05), but not significantly different for adenovirus. The proportions of positive faecal samples were 1% vs. 10% for adenovirus (p<0.00001) and 3.3% vs. 12% for norovirus (p<0.0001), but not significantly different for rotavirus. The proportions of enterovirus positive samples were 3.5% vs 21.6% (p<0.00001). Conclusion: The incidence of several paediatric infectious diseases mainly of viral aetiology declined significantly during the Covid-19 pandemic. Some common respiratory viruses were almost completely absent. The first cases of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection were detected in Norway late February 2020. Several measures to reduce spread of the virus were introduced from early March 2020; handwashing, social distancing, stay home when sick, as well as a six-week nationwide lockdown from March 12 th 2020. City of Oslo and surrounding areas reported the highest incidence of SARS-Cov-2 cases in Norway during the Covid-19 pandemic (1, 2) . In this region, infection control measures were maintained throughout most of the pandemic until late September 2021, except for facilitations of the measures for some periods mainly during the summer 2020. Schools and kindergartens were closed six to eight weeks during the initial nationwide lockdown. In Oslo, schools were also closed for shorter periods from late autumn 2020 and throughout the pandemic, related to local outbreaks. Severe disease from SARS-CoV-2 is rare in children and Covid-19 hospitalisation rates have been low compared to adult age groups (2) (3) (4) . The total number of all cause hospitalisations at The Department of Paediatric and Adolescent Medicine, Oslo University Hospital declined during 2020. We aimed to specifically investigate the incidence of selected infectious diseases as well as the incidence of different viruses other than SARS-CoV-2 among children admitted to our department during the Covid-19 pandemic 2020-2021 compared to previous years. The Department of Paediatric and Adolescent Medicine, Oslo University Hospital is the primary hospital for most children in Oslo with a catchment area covering 107570 individuals aged 0-18 years (5). We collected data for the period April 1 st 2020 -March 31 st 2021 (the pandemic period) and for the corresponding 12 months periods during 2017-2018, 2018-2019 and 2019-2020, respectively (the pre-pandemic period). The total number of hospital contacts (outpatient contacts and overnight hospitalisations) for patients aged 0-18 years with selected ICD-10 infectious disease diagnoses were collected from the Hospital Diagnosis and Procedure Registry. Pearson's Chi-square test and Fischer exact test were used to compare categorical data (incidence of infectious disease diagnoses and proportion of positive virus test results). Ethical board review and collection of informed consent were not required for this study because only anonymised register data were collected. The total number of hospital contacts at Oslo University Hospital for patients aged 0-18 years with selected ICD-10 infectious disease diagnoses during the pandemic period compared to the pre-pandemic period are shown in Table 1 . The proportion of nasopharyngeal samples positive for selected airway viruses and faecal samples positive for gastrointestinal viruses during the same periods are shown in Table 2 . The proportion of clinical samples of different origin positive for enterovirus is also shown in Table 2 . The seasonality of the proportions of positive samples for selected viruses is shown in Figure 1 The proportion of norovirus positive faecal samples was also significantly lower during the pandemic period (3,3%) compared to the pre-pandemic period (12%). In contrast, the level rotavirus did not significantly decline during the pandemic. A live attenuated rotavirus vaccine was introduced in the Norwegian national immunisation programme in October 2014, and the incidence of rotavirus gastroenteritis declined significantly the following four years period (12). The immunisation programme was maintained throughout the Covid-19 pandemic, and we speculate that rotavirus vaccine strains may have contributed to a stable level of rotavirus positive faecal samples during the pandemic period. Interestingly, the incidence of central nervous system infections of viral aetiology was significantly reduced during the pandemic period, although the total number of patients is small. Detection of enterovirus was significantly reduced, indicating that infection control measures also effectively reduce transmission of this group of viruses. The incidence of Lyme Borreliosis increased, although not statistically significant. This tickborne disease is endemic in most parts of southern Norway and we speculate that an increased incidence may be due to more outdoor activities in woods and fields during the pandemic. Finally, a higher threshold to contact the health services during the pandemic due to fears of contracting SARS-CoV-2 or to overburden the services may have contributed to lower detection rates of infectious diseases. However, the total number of contacts of children with pyelonephritis only modestly decreased during the pandemic. Looking at the subgroup of hospitalised children with pyelonephritis, the incidence did not significantly decrease. The Norwegian Institute of Public Health. Daily report and statistics about coronavirus and COVID-19 2021 Risk factors for SARS-CoV-2 infection and hospitalisation in children and adolescents in Norway: A nationwide population-based study Features of 20 133 UK patients in hospital with covid-19 using the ISARIC WHO Clinical Characterisation Protocol: prospective observational cohort study Clinical characteristics of children and young people admitted to hospital with covid-19 in United Kingdom: prospective multicentre observational cohort study Bronchiolitis in COVID-19 times: a nearly absent disease? Consequences of coronavirus disease-2019 (COVID-19) lockdown on infection-related hospitalizations among the pediatric population in Denmark Virusvirus interactions impact the population dynamics of influenza and the common cold Efficacy of ethanol against viruses in hand disinfection Respiratory virus shedding in exhaled breath and efficacy of face masks Physical distancing in schools for SARS The Lancet Respiratory medicine ☒ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work Great thanks to Ingrid Lundeby for data extraction. None of the authors have any conflict of interests to declare.