TORONTO -- Ontario’s top health official is insisting that transmission of COVID-19 within schools continues to be “minimal,” despite a pronounced rise in the number of school-related cases since classes resumed earlier this month.

Chief Medical Officer of Health Dr. Kieran Moore made the comment during a briefing on Tuesday afternoon, hours after the Ministry of Education reported another 293 new school-related cases over a three-day period that ended Monday afternoon.

That is up from the 169 new cases reported over the same three-day time period last week.

The rolling seven-day average now stands at 118.4.

“We're monitoring this situation very closely and as expected, most cases are contracted in the community and not in the school themselves,” Moore said. “When cases do occur in school, transmission to date has proven to be minimal with the majority of outbreaks contained at two to three cases. This is thanks to the school community following the public health measures as well as the rapid response from our school boards and public health units.”

Ontario has seen a steady increase in the number of school-aged children testing positive for COVID-19 since classes resumed earlier this month, however it remains unclear how much of the increase is being driven by the bump in testing volumes that has coincided with the reopening of schools.

The latest data released by the ministry on Tuesday indicates that there are now 1,009 active cases associated with Ontario’s schools, including 874 among students and 117 among staff.

At this time last year there were only 91 active school-related cases, though many boards pushed back the start to the academic year in 2020 as they scrambled to implement new COVID-19 protocols.

As of Monday there were also 593 schools with at least one confirmed case of COVID-19, compared to 75 at this point in 2020.

“As we see during the influenza season every year transmissible respiratory viruses do impact our schools and certainly COVID-19 is no exception,” Moore said. “Over the first few weeks of the school year there have been 1,046 confirmed cases of COVID-19 (including those no longer active) amongst students and staff who attend school in-person. But with over two million students and over 300,000 education workers and school partners this is not cause for alarm as in-person learning continues to remain safe.”

Dozens of classes self-isolating

While there is currently only one school that has closed due to a COVID-19 outbreak - St. Joseph's Catholic High School in Windsor – at least 124 classrooms in the Greater Toronto and Hamilton Area have been switched to remote learning due to positive cases.

That number, it should be noted, is likely an underrepresentation of the true number of students self-isolating as a number of major boards - including the Toronto District School Board - don’t publicly post data on the number of classrooms that have been temporarily switched to remote learning.

During a press conference earlier on Tuesday, Toronto’s Medical Officer of Health Dr. Eileen de Villa said that she has already heard from parents that the return to the classroom is “improving learning and improving moods” and remains convinced that the benefits of in-person learning are “immeasurable,” even as Ontario continues to report in excess of 100 new school-related cases of COVID-19 each day.

She said that she is also hopeful that the eventual approval of COVID-19 vaccines for children between the ages of 5 and 11 will make it “even harder for COVID-19 to spread.”

“Until that day vaccinated Torontonians are what we need. We are our best answer and our best defence. Vaccinating as many of us who are eligible is the best way to protect those five to 11 year olds waiting on that approval and what is good for those children is what is good for all of us,” she said.

There are now nearly 400 school-related active cases of COVID-19 in GTHA school boards.

The Toronto District School Board has reported 107 of those cases.

On Tuesday it reported an additional 11 cases, including two more at King George Public School in Runnymede where an outbreak was declared last week.

That school now has eight confirmed cases among students.

Toronto Public Health also declared an outbreak at Scarborough’s École élémentaire catholique français‎ St-Michel on Tuesday after determining that at least two cases at the school are “linked.”

Outbreaks have also previously been declared at three other Toronto schools - Elmlea Junior Public School in Etobicoke and Alvin Curling Public School and St. Lawrence Catholic School in Scarborough.