TORONTO -- Ontario's top doctor says he "absolutely" expects a rise in COVID-19 cases starting in September and the province is already preparing to respond to the potential surge.

Ontario's Chief Medical Officer of Health Dr. Kieran Moore made the comment on Tuesday while providing a COVID-19 update.

Moore said he has seen modelling from Public Health Ontario and the province’s science table that suggests cases will increase when the cooler weather arrives. 

"I absolutely expect a rise in COVID activity in September," Moore said, adding that an increase in cases would mainly affect the unvaccinated population. 

"Last summer, we had the same type of lull," Moore said. "Ontarians are taking great advantage of the outdoors, but as soon as we come back [to] the indoors, normally, all respiratory viruses start to come back, especially around the third week of September."

He said Ontario health officials are already working with local public health units to prepare for a potential surge in cases.

He said there’s a "real call to arms" in Ontario to increase vaccine coverage before September when people return to more indoor activities.

"We really, really want to have the highest immunization rate possible heading into September," Moore said. "No one wants to see our health system impacted … All of that hospital activity is preventable through immunization."

MOVING TO A COMPLETE REOPENING

Moore seemed confident on Tuesday that Ontario will reach the targets laid out by the government to leave Step 3 of its reopening plan by Aug. 6, but said there is still lots of work to be done before then.

Step 3 begins on July 16 and will remain in place for at least 21 days. 

In order to move beyond Step 3, at least 80 per cent of the eligible population aged 12 and up needs to have received one dose of a COVID-19 vaccine and 75 per cent should receive their second dose.

Officials say that in order to move forward, no public health unit should have less than 70 per cent of their population fully vaccinated.

Upon meeting these thresholds, the vast majority of public health and workplace safety measures, including capacity limits for indoor and outdoor settings and limits for social gatherings, will be lifted.

Immunization levels in Ontario are currently at 78 per cent for first doses and 54.6 per cent for second doses. 

"If we want to move safely and effectively through Step 3 to a complete reopening of our economy, we've got our work cut out for us," Moore said. 

Moore said Ontario has the time and vaccine supply to hit the targets by Aug. 6 but Ontarians need to continue getting vaccinated. 

He said the number of doses being administered per day has dropped in Ontario in recent days, with first doses lagging even further behind.

He said he understands people get busy in the summer but that they need to carve out time to get vaccinated. 

"It's a challenge to all Ontarians. If we want to get through to the next phase of reopening, which is a complete reopening with no public health measures, we’ve got work cut out for us."