LAUSR

Significance We provide causal evidence on the impact of opening schools in a situation under virus variants and substantial vaccination rates in the adult population. We show that schools under regular and mandatory rapid testing of the studentship mitigated the growth in case numbers leading to Germany’s fourth pandemic wave in autumn 2021. Our results have important implications for the design of future nonpharmaceutical interventions to mitigate the spread of severe acute respiratory syndrome coronavirus 2 and comparable future diseases. Keeping schools open under mandatory testing rules can provide a means to track infection rates. Our results suggest that school closures, given substantial economic and societal costs, should be thought of as the “last resort,” even if inevitable at some point.