Estimating the impact of reopening schools on the reproduction number of SARS-CoV-2 in England, using weekly contact survey data

Munday, James D. and Jarvis, Christopher I. and Gimma, Amy and Wong, Kerry L.M. and van Zandvoort, Kevin and Liu, Yang and Hellewell, Joel and Davies, Nicholas G. and Villabona-Arenas, C. Julian and Eggo, Rosalind M. and Endo, Akira and Bosse, Nikos I. and Gibbs, Hamish P. and Pearson, Carl A.B. and Sun, Fiona Yueqian and Jit, Mark and O’Reilly, Kathleen and Jafari, Yalda and Atkins, Katherine E. and Waterlow, Naomi R. and Rosello, Alicia and Chan, Yung Wai Desmond and Foss, Anna M. and Quilty, Billy J. and Russell, Timothy W. and Flasche, Stefan and Procter, Simon R. and Waites, William and Barnard, Rosanna C. and Kucharski, Adam J. and Jombart, Thibaut and Medley, Graham and Lowe, Rachel and Krauer, Fabienne and Tully, Damien C. and Prem, Kiesha and Lei, Jiayao and Brady, Oliver and Sandmann, Frank G. and Meakin, Sophie R. and Abbas, Kaja and Knight, Gwenan M. and Quaife, Matthew and Koltai, Mihaly and Abbott, Sam and Clifford, Samuel and Funk, Sebastian and Edmunds, W. John, CMMID COVID-19 Working Group (2021) Estimating the impact of reopening schools on the reproduction number of SARS-CoV-2 in England, using weekly contact survey data. BMC Medicine, 19 (1). 233. ISSN 1741-7015 (

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Background: Schools were closed in England on 4 January 2021 as part of increased national restrictions to curb transmission of SARS-CoV-2. The UK government reopened schools on 8 March. Although there was evidence of lower individual-level transmission risk amongst children compared to adults, the combined effects of this with increased contact rates in school settings and the resulting impact on the overall transmission rate in the population were not clear. Methods: We measured social contacts of > 5000 participants weekly from March 2020, including periods when schools were both open and closed, amongst other restrictions. We combined these data with estimates of the susceptibility and infectiousness of children compared with adults to estimate the impact of reopening schools on the reproduction number. Results: Our analysis indicates that reopening all schools under the same measures as previous periods that combined lockdown with face-to-face schooling would be likely to increase the reproduction number substantially. Assuming a baseline of 0.8, we estimated a likely increase to between 1.0 and 1.5 with the reopening of all schools or to between 0.9 and 1.2 reopening primary or secondary schools alone. Conclusion: Our results suggest that reopening schools would likely halt the fall in cases observed between January and March 2021 and would risk a return to rising infections, but these estimates relied heavily on the latest estimates or reproduction number and the validity of the susceptibility and infectiousness profiles we used at the time of reopening.