Background: School closures are a subject of debate during the present coronavirus disease 2019 (COVID-19) pandemic. Because children are not the main driver of COVID-19 transmission in the community, school education must be prioritized in conjunction with appropriate infection prevention and control measures, as determined by local COVID-19 incidence.
Methods: We investigated the causes and transmission routes of a primary school cluster of COVID-19 that occurred during November and December 2020 in Niigata, Japan.