Ontario’s School Reopening in Early 2021 Had Only Small Increase in COVID Cases, Study Shows

A family walk past the sign at Thorncliffe Park Public School in Toronto on Dec. 4, 2020. Frank Gunn/The Canadian Press

School reopenings in Ontario only resulted in a small increase in COVID-19 cases in the province in early 2021, a new study finds.

The study, published in Health Affairs, a U.S. peer-reviewed journal on health policies, sought to determine the change in COVID-19 case rates in the weeks after the reopening of the province’s public schools.

“We conducted an event study regression examining whether the reopening of elementary and secondary schools was associated with a change in community COVID-19 case growth rates,” said the study, published this month.

Specifically, the authors focused on the period starting Dec. 26, 2020, through March 8, 2021—during the time when the provincewide shutdown was enacted until three weeks after schools in the final public health units were permitted to reopen.

Had schools not reopened, the study estimated that 213 fewer cases of the virus would have occurred in Ontario between Dec. 26, 2020, and Feb. 18, 2021, which is roughly 0.08 percent fewer cases.

The analysis was conducted using PCR tests done during the study period, obtained from the Institute for Clinical Evaluative Sciences, a non-profit research institute that provides researchers access to Ontario’s health-related data, including anonymous patient records, and clinical and administrative databases.

“These data sets captured more than 90 percent of tests completed in Ontario and 100 percent of confirmed cases,” the study said.

The authors said the reopening approach taken by the provincial government after the lockdown order offered them an opportunity to estimate the case rates more effectively.

“A regionalized approach was taken to reopen schools throughout early 2021 without any other opening of the economy, offering a unique natural experiment to estimate the impact of school reopening on community transmission,” they said.

The authors argued that even though their findings suggest additional COVID-19 cases are to be expected after the reopening of the schools, the risks may be manageable with “sufficient, layered mitigation policies” such as smaller class sizes, masking, and cohorting.

However, they also noted that “this study was unable to ascertain whether these measures alone, without the need to also close schools, could have reduced case growth rates as effectively.”