key: cord-0882286-x2g8gspz
authors: Perez‐Lopez, Andres; Hasan, Mohammad; Iqbal, Muhammad; Janahi, Mohammed; Roscoe, Diane; Tang, Patrick
title: Dramatic decrease of laboratory‐confirmed influenza A after school closure in response to COVID‐19
date: 2020-07-07
journal: Pediatr Pulmonol
DOI: 10.1002/ppul.24933
sha: f0acc9f85e33ee48655559d3509bcdacb31d54e9
doc_id: 882286
cord_uid: x2g8gspz

The novelty of the coronavirus disease 2019 (COVID-19) has led some researchers to use influenza models and changes in influenza activity to infer the impact of social distancing measures to mitigate the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 This article is protected by copyright. All rights reserved.

March. 4 Although the rates of common human coronaviruses (common HCoVs), including types 229E, HKU1, NL63, and OC43, did not change significantly before and after school closure (Table 1) , it should be kept in mind that the annual antigenic drift and periodic antigenic shifts of influenza A give this virus access to substantial pools of individuals without a pre-existing immunity, similar to SARS-CoV-2 which is circulating in a completely naïve population. In contrast, other seasonal respiratory viruses like common HCoVs typically undergo less annual antigenic variations allowing maintenance of some degree of immunity within the community that may explain their dissimilar epidemiology to influenza A. 5 The study of transmission dynamics of SARS-CoV-2 among children has been limited by the suppression of contacts in kindergarten and primary school classrooms, the highest-risk setting for transmission of respiratory pathogens among school-age children, after early implementation of school closure in the majority of countries worldwide. In fact, the notion that children with SARS-CoV-2 infection are less infectious than adults should be considered cautiously in light of emerging evidence. For instance, a large study carried out in Shenzhen, China, involving 391 PCR-confirmed cases and tracing of 1286 contacts observed a similar household secondary attack rate among children younger than 10 years compared with that in the general population (7.4% vs 6.6%). 6 A German study with a small number of children and adolescents reported similar mean viral loads in respiratory tract specimens among school-age children and adults, although the maximum range of viral loads was higher in age groups older than 20 years. 7 Putting these findings together with the fact that a great proportion of children are asymptomatic or mildly symptomatic, 8 it could be speculated that age-school children may represent a significant source of transmission to age groups at greater risk for a serious infection.

As of yet, there have been no controlled studies addressing transmission of SARS-CoV-2 in schools. In fact, some countries, including Israel, South Korea, and France, have had to immediately close schools after re-opening because of COVID-19 transmission. [9] [10] [11] Although future research may prove otherwise, at this moment, it may be reasonable to use influenza A as a surrogate marker to estimate the contribution of school closure in combination with other social distancing measures to curb COVID-19 spread, until the risk of acquisition of SARS-CoV-2 from children is fully elucidated and more conclusive data on the impact of nonpharmaceutical interventions during this pandemic is available. 

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Decreased influenza incidence under COVID-19 control measures

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More schools across Israel, many in Tel Aviv, closed due to COVID-19 infections. The Times of Israel

South Korea closes schools again amid coronavirus spike, days after reopening. The Washington Post

70 cases of COVID-19 at French schools days after reopening

Dramatic decrease of laboratoryconfirmed influenza A after school closure in response to COVID-19

Abbreviations: CI, confidence interval; Common HCoVs, common human coronaviruses (229E, HKU1, NL63, and OC43); hMPV, human metapneumovirus; Parainfluenza, parainfluenza viruses 1-4; Rhino/entero, rhinovirus/enterovirus; RR, relative risk; RSV: respiratory syncytial virus. aNasopharyngeal swabs were tested for respiratory pathogens using the Xpert Xpress Flu/RSV assay (Cepheid, Sunnyvale, CA) and BioFire FilmArray Respiratory Panel 2 plus (bioMerieux, Marcy l'Etoile, France).