Do school closures reduce community transmission of COVID-19? A systematic review of observational studies

ABSTRACT

BackgroundSchool closures are associated with significant negative consequences and exacerbate inequalities. They were implemented worldwide to control SARS-CoV-2 in the first half of 2020, but their effectiveness, and the effects of lifting them, remain uncertain. This review summarises observational evidence of the effect of school closures and school reopenings on SARS-CoV-2 community transmission. MethodsThe study protocol was registered on Prospero (IDCRD42020213699). On 07 January 2021 we searched PubMed, Web of Science, Scopus, CINAHL, the WHO Global COVID-19 Research Database, ERIC, the British Education Index, the Australian Education Index, and Google. We included observational studies with quantitative estimates of the effect of school closures/reopenings on SARS-CoV-2 community transmission. We excluded prospective modelling studies and intra-school transmission studies. We performed a narrative synthesis due to data heterogeneity. We used the ROBINS-I tool to assess risk of bias. FindingsWe identified 7,474 articles, of which 40 were included, with data from 150 countries. Of these 32 studies assessed school closures, and 11 examined reopenings. There was substantial heterogeneity between school closure studies, with half of the studies at lower risk of bias reporting reduced community transmission by up to 60%, and half reporting null findings. The majority (n=3 out of 4) of school reopening studies at lower risk of bias reported no associated increases in transmission. ConclusionsSchool closure studies were at risk of confounding and collinearity from other non-pharmacological interventions implemented around the same time as school closures, and the effectiveness of closures remains uncertain. School reopenings, in areas of low transmission and with appropriate mitigation measures, were generally not accompanied by increasing community transmission. With such varied evidence on effectiveness, and the harmful effects, policymakers should take a measured approach before implementing school closures; and should look to reopen schools in times of low transmission, with appropriate mitigation measures.