Is a fourth wave of COVID-19 even possible in Ontario at this point?

With vaccination rates skyrocketing, new case numbers dwindling, and economic reopening plans moving along at a clip, many in the province are starting to wonder if the pandemic might now be behind us.

It's a valid query; I mean, nearly 80 per cent of people aged 12 and over in Ontario have already received one dose of an approved vaccine. Just over 57 per cent are now considered fully immunized.

And yet, even with pandemic restrictions lifting consistently ahead of schedule, the threat of another outbreak — or multiple localized outbreaks — remains.

The province's new Chief Medical Officer of Health Dr. Kieran Moore actually expects case numbers to surge again once cooler weather arrives again this fall.

"I absolutely expect a rise in COVID activity in September," said Moore while speaking to the press during a COVID-19 update on Tuesday, noting that modelling data from the science table has "shown that we can expect a rise in cases as we go indoors as the cold weather comes."

Moore pointed out that we saw the same type of lull in viral activity last summer... and we all know how that turned out.

While vaccines weren't widely available last fall, neither was Toronto yet dealing with aggressive mutations of the coronavirus such as the Delta variant.

"Delta will want to surge and return in September, if not earlier. All you have to do is look around the globe and see the increased activity in countries where Delta has done unchecked," warned Moore on Tuesday.

"We are preparing, from a local public health agency vantage point, to respond to a surge, and hence the real call to arms that we need now to build the best immunity through immunization possible to protect our population."

Moore is urging all eligible Ontario residents who haven't yet been vaccinated to get their shots as soon as possible, and to follow all other recommended public health measures, such as frequent hand washing and the use of masks.

"No one wants to see our health system impacted, no one wants to see more people in the intensive care unit… and all of that hospital activity is preventable through immunization," said Moore on Tuesday.

The 4th Wave in underway in the UK & South Africa. It is beginning in the US. Ontario needs to remain vigilant. #COVID19Ontario https://t.co/M3sjpiMbjU

— James Ryan (@JamesJJRyan) July 12, 2021

Moore isn't the only Ontario health official warning of potential future surges and outbreaks among the unvaccinated.

Middlesex-London Health Unit Medical Officer Dr. Chris Mackie says he's already observing a "fourth wave of COVID" among the roughly one fifth of people in his region who have yet to be immunized.

"Essentially, we have a fourth wave of COVID right now that is moving through our unvaccinated population,"  he said this week. "There's a bit of spillover to those who are vaccinated, and so it's so important that we all do get the vaccine."

Ottawa Hospital senior scientist Dr. Doug Manuel similarly told the CBC recently that communities with lower vaccination levels will likely see outbreaks this fall, particularly as a result of the Delta variant.

"The question is how many and how bad — and whether we can easily contain them," he said. "It's going to be like a flu season, maybe, for people who are vaccinated... But people who aren't vaccinated, this is not the flu."

As for Moore, while he believes that another wave is possible among the unvaccinated this fall, he did say on Tuesday that he is confident in August 6 as a "doable date" to exit Step 3 of the Ford government's reopening framework and move back to "whatever normal is in the post-COVID world."