Do school closures and school reopenings affect community transmission of COVID-19? A systematic review of observational studies

Abstract

IntroductionSchool closures are associated with significant negative consequences and may exacerbate inequalities. They were implemented worldwide to control SARS-CoV-2 in the first half of 2020, but their effectiveness remains uncertain. This review summarises the empirical evidence of their effect on SARS-CoV-2 community transmission.MethodsThe study protocol was registered on Prospero (ID:CRD42020213699). On 12 October 2020 we searched PubMed, Web of Science, Scopus, CINAHL, the WHO Global COVID-19 Research Database, ERIC, the British Education Index, and the Australian Education Index. We included empirical 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.ResultsWe identified 3,318 articles, of which ten were included, with data from 146 countries. All studies assessed school closures, and one additionally examined re-openings. There was substantial heterogeneity between studies. Three studies, including the two at lowest risk of bias, reported no impact of school closures on SARS-CoV-2 transmission; whilst the other seven reported protective effects. Effect sizes ranged from no association to substantial and important reductions in community transmission.DiscussionStudies were at risk of confounding and collinearity from other non-pharmacological interventions implemented close to school closures. Our results are consistent with school closures being ineffective to very effective. This variation may be attributable to differences in study design or real differences. With such varied evidence on effectiveness, and the harmful effects, policymakers should take a measured approach before implementing school closures.Panel: ‘Research in context’Evidence before this studyA previous systematic review, published by some of us in April 2020, found good evidence that school closures are effective for the control of influenza, but limited evidence of effectiveness for coronavirus outbreaks. At the time there was no available empirial evidence from the COVID-19 pandemic.Added value of this studyThis study is the first systematic review of the empirical evidence from observational studies of the effect of school closures and reopenings on community transmission of SARS-CoV-2. We include 10 studies, covering 146 countries. There was significant heterogeneity between studies. Some studies reported large reductions in incidence and mortality associated with school closures, however, studies were at risk of confounding and collinearity, and studies at lower risk of bias reported no association.Implications of all the available evidenceThe evidence is consistent with either no effect, or a protective effect of school closures. With such varied evidence on effectiveness, and the harmful effects, policymakers should take a measured approach before implementing school closures.

Systematic review of empirical studies comparing the effectiveness of non-pharmaceutical interventions against COVID-19

“…As the epidemiological situation has improved, reopening schools has become imperative. Walsh et al 59 found that there is no increase in community transmission of COVID-19 after reopening schools in a low transmission context with appropriate mitigation measures, as it was observed in Norway and Denmark 66 . However, in countries like Germany, that reopened schools when community transmission was still high, it can lead to an increase in the growth rate 66 .…”

“…They found that the effect of school closures was comparatively lower than other measures. In a recent systematic review of observational studies analysing school closing and reopening Walsh et al 59 found that half of the studies with lower risk of bias concluded that school closing reduced community transmission while half of the studies found no effect. Other analyses 60 , 61 , 62 , 63 , 64 , 65 suggest that school closingmay have been a more important factor during the first wave of the COVID-19 epidemic than initially thought.…”

SARS-CoV-2 infection and transmission in school settings during the second wave in Berlin, Germany: a cross-sectional study

“…In observational US data from early 2020, school closure was associated with significant declines in COVID-19 incidence and mortality, 25 whereas in systematic review of observational studies, effects of school closure are inconsistent. 8 Several modelling studies - usually from the first wave of the pandemic - suggest modest to substantial associations between school closures and incidence. 5,26 These include estimates of 40-60% reduced peak incidence, 26 and of reducing the reproduction number by more than a third.…”

“…6,7 Observational studies on the association of school closures with community transmission have yielded inconsistent results, ranging from none to substantial reduction. 8 When considering infection risks, a distinction needs to be made between schools, students and age-typical, contextual whereabouts, e.g., public transport or after-school meetings. Limited data suggest that schools are not high-risk settings for SARS-CoV-2 transmission between students and/or staff.…”

Closing schools is not evidence based and harms children

“…Moreover, they do not account for indirect effects of school closures which prevent parents from working outside the home. A systematic review26 of observational studies showed that in those studies with lowest risk of bias, school closures had no discernible effect on SARS-CoV-2 transmission.…”