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

KEY POINTS

• School 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 children’s development and mental health, and since they are less likely to have severe COVID-19 outcomes than adults.

• Existing 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-à-vis other age groups in Montréal, Toronto and Calgary during Fall 2020.

• The case of Montréal 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.

• Our 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.