BARRIE, ONT. -- While COVID-19 infections continue to climb down from a pandemic high, Simcoe-Muskoka's top doctor warns letting loose over the long weekend could have disastrous consequences.

"We will end up with a fourth wave extending through the summer if we're not cautious," Medical Officer of Health Dr. Charles Gardner said Tuesday.

"Despite the fact that this is the long weekend and traditionally people have gone elsewhere, they need to stay close to home."

The warning comes as local COVID-19 cases and hospitalizations are the lowest they've been in five weeks.

The Simcoe Muskoka District Health Unit reported 42 new infections and three new hospitalizations on Tuesday.

The region has now seen 11,446 cases of the virus since the pandemic began, 767 of them considered active. Twenty-eight people are being treated for the virus in area hospitals.

But Gardner cautions transmission rates are still higher than they were in February when restrictions were last loosened. In a break with other medical leaders, he advises against reopening outdoor activities.

Ontario's Health Minister says a reopening plan for the province is coming "very soon".

Gardner says that plan has to be one that is clear and ensures that people don't flock to the region from COVID-19 hotspots.

On the day vaccinations opened up to all Ontarians 18 and over, Gardner says 56 percent of the region's adult population has received at least one shot. He hopes that rate improves to 75 percent by the end of June.

with files from Mike Arsalides