The health unit has declared a COVID-19 outbreak at Hillcrest Public School in Barrie after two positive cases were confirmed.
One classroom has been closed as a result, but the elementary school remains open.
Simcoe Muskoka's top doc said there was evidence transmission likely happened in the school environment. The affected students and staff are in isolation.
Meanwhile, the Catholic board confirmed one positive case at Holy Family Catholic Elementary School in Alliston.
One classroom has been closed as a result, but the school remains open.
Click here for a complete list of schools with COVID-19 cases across the region.
The health unit and school boards will not identify whether positive cases are among students or staff because of privacy laws.