Influenza A infections decreased most significantly, by more than 30-fold following school closures (RR 0.03, 95% CI 0.004 ,0.2). The infection rates of other respiratory viruses, including common human coronaviruses (HCoVs), varied slightly. The authors argue that annual and periodic antigenic drift give influenza A access to populations without pre-existing immunity, comparable to that of SARS-CoV-2.