Is a 4th pandemic wave likely? Ottawa experts weigh in

If a fourth wave of COVID-19 fuelled by the delta variant breaks out, it will spread primarily among susceptible, unvaccinated people, health experts say and likely arrive in fall when children go back to school.

What's more, it wouldn't just happen in the nation's capital, says University of Ottawa epidemiologist Raywat Deonandan,but would take placeprovincewide or even nationwide.

Deonandan has examined recent data from Los Angeles County, where the delta variant has started to circulate more widely.

"What we're seeing ... [is] that 98 per cent of the cases are in the unvaccinated [category],98 to 99 per cent of the deaths are in the unvaccinated," he said. "So this is entirely in the unvaccinated population, the susceptible population."

"If one does happen, it'll be a small wave, in my mind, and it probably won't overwhelm our health-care system."

Delta will soon be dominant strain: scientist

Ottawa Public Health hadpublicly confirmed 11 COVID-19cases involving the delta variant as of Sunday.

Dr. Doug Manuel, a senior scientist with The Ottawa Hospital, says it's only a matter of time before it becomes the dominant strainin Ottawa, even as total cases decline.

He says there's evidence it's making up about 70 per cent of cases in the province.

"If it wasn't for alpha and delta, we'd have no cases now. We'd be open because vaccination would have taken us there," said Manuel, who performs modelling of local COVID-19 numbers.

• Public health agency warns of fall COVID resurgence if delta variant becomes dominant strain

The delta variant, also known as B.1617.2, was first identified in India and is thought to be more transmissible than previous variants.

Avoidance depends on smart decision-making

While Deonandan is confident Canada can avoid a fourth wave, that outcome is dependent on governments making smart decisions.

The epidemiologist said federal and provincial governments need to continue putting vaccines in arms, shortening the time between doses, prioritizinghot spot areas where delta is present and resisting the temptation to reopen too quickly.

"It's that last one that I'm worried aboutbecause we havecalls right now to accelerate Stage 3 reopening," he said."I don't think it's warranted at the moment."

• Why Ontario's not hopping to Step 3 of reopening despite hitting vaccination targets

Deonandan believes another wave, if it happens at all, would likely come during the fall when children return to school.

While vaccinating 90 per cent of people would better insulate the populationagainst newly imported cases of the variant, it's more likely Ottawa and other regions will have vaccination levels in the 80s, Manuel said.

At those levels, Manuel said, communities with lower vaccination levels will see outbreaks.

"The question is how many and how bad and whether we can easily contain them," he said.

• 15 months, 3 waves: How COVID-19 coursed through the capital

According to Deonandan, factors not directly tied to vaccinations, like good ventilation in schools and outbreak suppression, will also play a role when it comes to preventing another wave, even if vaccinations aren't as high as health experts would like.

"You don't necessarily get a fourth wave," he said. "You get functional herd immunity."

But for those susceptible to the virus, Manuel said the possibility of a fourth wave driven by the delta variant shouldn't be taken lightly.

"It's going to be like a flu season, maybe, for people who are vaccinated," Manuel said. "But people who aren't vaccinated, this is not the flu."