A new American study reported that about 30 percent of COVID-19 cases among students and staff in schools across Boston could have been prevented if mask mandates had not been lifted.

The researchers also looked at more than 70 school districts to compare those with mask mandates to those without, and found that masking in schools was associated with a significantly lower number of COVID-19 cases.

When looking at COVID-19 only among staff, the effect of lifting masks was more pronounced: school districts that did not require masks had 81 additional cases per 1000 staff overall, with case rates approaching double those of schools that retained mask-wearing.

This study comes amid calls from health experts and officials for Canadians to start wearing masks again. Ontario Premier Doug Ford advised citizens on Sunday "to wear masks in crowded places," and the province's Chief Medical Officer is scheduled to recommend mask-wearing on Monday — but it is unclear if this advice will lead to a province-wide mask mandate in schools and businesses.

Also, mask mandates have completely disappeared in many parts of Canada this year, despite COVID-19 hospitalizations and deaths occurring at higher rates than in 2021.

As of November 7, there were 6,083 people hospitalized with COVID-19 in Canada, while last year, the highest number of people hospitalized with COVID-19 at the same time was 4,930, according to the federal government.