1. Inclusion criteria.

Population	Populations at risk of becoming infected with SARS‐CoV‐2 and/or developing COVID‐19 disease Students attending a year level corresponding to the primary or secondary educational stage (approx age 4‐18 yearsa) Teachers working in the school setting Other staff working in the school setting (e.g. facility managers, cleaning personnel, management, social workers, school health staff) Individuals indirectly impacted by the school setting (e.g. parents, carers, relatives, peers of directly impacted individuals, other members of the community)
Setting	School setting, i.e. in and around schools, including boarding schools (e.g. transportation to and from school and school‐related extracurricular activities are considered part of the school setting)
Interventions	Measures implemented to safely reopen schools and/or keep schools open during the SARS‐CoV‐2/COVID‐19 pandemic (including reactive school closures) For reactive school closures, the trigger for closing the school would have to lie within the school setting (e.g. number of cases within school)
Study designs	Studies that quantitatively assess impact (e.g. epidemiologic studies, modelling studies) Mixed methods studies that allow for extraction of quantitative impact measures Diagnostic studies that assess the impact of relevant interventions beyond diagnostic test accuracy

^aInternationally, there are important differences with regards to starting and finishing ages; we did not exclude studies that comprised students outside of this age range if students attended a year level corresponding to the primary or secondary educational stage.