Stage, Helena B.; orcid: 0000-0001-9938-8452; email: helena.stage@manchester.ac.ukShingleton, Joseph; orcid: 0000-0002-1628-3231; email: Joseph.Shingleton@phe.gov.ukGhosh, Sanmitra; orcid: 0000-0002-4879-7587Scarabel, Francesca; orcid: 0000-0003-0250-4555Pellis, Lorenzo; orcid: 0000-0002-3436-6487Finnie, Thomas; orcid: 0000-0001-5962-42112021-05-312021-05-312021-05-31Philosophical Transactions of the Royal Society B, volume 376, issue 1829, page 20200277http://hdl.handle.net/10034/624782From The Royal Society via Jisc Publications RouterHistory: accepted 2020-12-02, pub-electronic 2021-05-31, pub-print 2021-07-19Article version: VoRPublication status: PublishedFunder: Wellcome Trust; Id: http://dx.doi.org/10.13039/100004440; Grant(s): 202562/Z/16/ZFunder: Royal Society; Id: http://dx.doi.org/10.13039/501100000288; Grant(s): 202562/Z/16/ZFunder: Department for Health and Social CareFunder: Canadian Institutes of Health Research; Id: http://dx.doi.org/10.13039/501100000024; Grant(s): 2019 Novel Coronavirus (COVID-19) rapid researchFunder: Medical Research Council; Id: http://dx.doi.org/10.13039/501100000265; Grant(s): MC UU 00002/11We investigate the effect of school closure and subsequent reopening on the transmission of COVID-19, by considering Denmark, Norway, Sweden and German states as case studies. By comparing the growth rates in daily hospitalizations or confirmed cases under different interventions, we provide evidence that school closures contribute to a reduction in the growth rate approximately 7 days after implementation. Limited school attendance, such as older students sitting exams or the partial return of younger year groups, does not appear to significantly affect community transmission. In countries where community transmission is generally low, such as Denmark or Norway, a large-scale reopening of schools while controlling or suppressing the epidemic appears feasible. However, school reopening can contribute to statistically significant increases in the growth rate in countries like Germany, where community transmission is relatively high. In all regions, a combination of low classroom occupancy and robust test-and-trace measures were in place. Our findings underscore the need for a cautious evaluation of reopening strategies. This article is part of the theme issue ‘Modelling that shaped the early COVID-19 pandemic response in the UK’.Licence for VoR version of this article: http://creativecommons.org/licenses/by/4.0/ARTICLESResearch articlesCOVID-19school closureschool reopeningnon-pharmaceutical interventionsarticle2021-05-31