In-person schooling and COVID-19 transmission in Canada's three largest cities

In North America and Europe, the Fall 2020 school term has coincided with the beginning of the second wave of the novel coronavirus (COVID-19) pandemic, sparking a heated debate about the role of in-person schooling for community transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This issue has immediate policy relevance for deciding how to operate schools safely as the pandemic unfolds, new variants of SARS-CoV-2 are circulating, and immunization coverage remains low. We contribute to this debate by presenting data on trends in COVID-19 weekly incidence among school-aged children 0-19 years old vis-a-vis other age groups during Fall 2020 in Canadas three largest cities: Montreal, Toronto and Calgary. We interpret these trends in light of the different back-to-school policies and other public health measures implemented in the three cities over the observation period. KEY POINTSO_LISchool closures are an effective measure to reduce the overall incidence of the novel coronavirus (COVID-19). Nonetheless, there is a general consensus that the decision to close schools to control the spread of COVID-19 should be used as last resort because of the negative impact on childrens development and mental health, and since they are less likely to have severe COVID-19 outcomes than adults. C_LIO_LIExisting evidence highlights the importance of adopting appropriate mitigation strategies for limiting COVID-19 community spread when returning to in-person schooling. To understand the association between in-person schooling and COVID-19 transmission given different mitigation strategies, especially universal masking and distance learning, we compare how the second wave of COVID-19 has affected school-aged children age 0-19 years old vis-a-vis other age groups in Montreal, Toronto and Calgary during Fall 2020. C_LIO_LIThe case of Montreal attests to the negative consequences of not implementing recommended migration strategies when reopening schools, even when public health measures such as gatherings restrictions are in place to maintain low levels of community transmission. On the contrary, school measures adopted in Toronto (optional distance learning and masking mandates), have limited the role of COVID-19 transmission among school-aged children for overall community transmission. In Calgary, this effect has been smaller, likely because public health measures to limit COVID-19 community spread were not introduced until early December 2020. C_LIO_LIOur findings have immediate policy relevance for deciding how to operate schools safely as the pandemic unfolds, new variants of SARS-CoV-2 are circulating, and immunization coverage remains low. C_LI