Canada's Fourth Wave Driven by COVID's Delta Variant

"We've got to get to 85, 90 percent of the population immunized before we can have the conversation about herd immunity. We're nowhere near that."

"Epidemics are all about susceptible populations, and who's susceptible? The unvaccinated."

"I think this is particularly true of conservative leaders [fear of accusations of limiting freedoms] whose identity is built upon reducing government control, and not increasing it."

"Some people have returned to life as normal, and I understand why; you feel you've been doubly vaccinated why not go back to normal?"

"But they're interacting with unvaccinated people to an extent that is unhealthy and in the context of Delta hyper-transmissibility, this is what you get."

"What I'm hoping happens is that people get a lid on this -- in Ontario cases go up to maybe 500, then vaccination uptake increases considerably and we drive it down to nothing and let public health handle the rest."  

"Previously we could have said the kids aren't really vulnerable, they do get [COVID-19] but not really as much, and if they get it they're asymptomatic, they're much less likely to be hospitalized."

"That does not seem to be the case any longer, at least not to the same extent."

Raywat Deonandan, epidemiologist, University of Ottawa 

Rising vaccination rates, alongside public health measures like mask-wearing, may ward off the worst outcomes of a fourth wave, even as delta spreads. But medical experts warn pressure on Canada's hospital system remains a possibility if cases continue to spike. (Graham Hughes/The Canadian Press)

"We're reopening. We didn't just rip the Band-Aid off and go straight from stage zero, to step three. We took our time."

"We're in a highly uncertain period right now in the sense that this is entirely up to us. I don't think it's inevitable that we have a bad fourth wave."

"If we were to let the virus spread unmitigated we would expect really high attack rates in kids. And what I think we are seeing in the Southern U.S. states is exactly that; you have high rates of infection and you are seeing those rare outcomes more frequently; just because there are so many infections happening." 

Ashleigh Tuite, epidemiologist, Dalla Lana School of Public Health, University of Toronto

With phased-in re-opening in Ontario and the introduction of more relaxed attitudes about attending gyms and indoor dining, it was generally acknowledged that even with all appropriate-level cautions still in order, there would be a gradual rise once more in COVID case numbers. Which is exactly what has and is occurring; confirmation that infection numbers are on the increase, even with a measured response in re-opening. 

It is the situation yet to come looming on the near horizon that fixates the minds of health professionals. Now that the rise is unfolding, what does the near future hold? Ontario is a highly vaccinated province, but even so, there are inoculation gaps where the numbers are insufficiently high to rate as capable of fully halting further transmission. 

The Delta variant was identified  as one of the most infectious viruses in history, according to epidemiologist Larry Brilliant whose assistance in eradicating smallpox led to fame. Even though 61 percent of over 12-years-of-age Canadians covering those in their teens, and on upward from 18 to the elderly bracket who have a vaccination rate against COVID of 73 percent, that rate must continue growing substantially for full-population protection against the virus.

There has been a recent rise in case numbers across Ontario, British Columbia Alberta and Quebec even though case numbers come nothing near the explosive rate seen across the border in the United States driven by the Delta strain of COVID. The seven-day moving average in Canada as a whole stands at 945 reported daily, between July 30 and August 4; a 48 percent increase week over recent week.

In British Columbia, modelling predicts the province could see 1,000 new confirmed infectious daily by September. Central Okanagan has seen a case surge that brought in new restrictions on bars, nightclubs and personal gatherings indoors and out. British Columbia hospitals have seen a slight increase in hospitalizations, mostly representing unvaccinated people in their 40s and 50s.

 

A pedestrian walks past an electronic information board displaying a COVID-19 information relating to a "variant of concern in the area" in Blackburn, northwest England, on June 16, 2021. Photo by OLI SCARFF /AFP via Getty Images

Data from the Public Health Agency of Canada and from Ontario indicate unvaccinated people now account for the majority of reported cases, for hospitalizations and for deaths. Recently a Public Health Ontario summary of infections following vaccination drives found unvaccinated people to be about eight times likelier to become infected in comparison to the doubly-vaccinated. The unvaccinated age 60 and up are 15 times likelier to be hospitalized than are the fully vaccinated.

In Canada as a whole -- between mid-December and 17 July -- 5,896 deaths attributable to COVID were reported in the unvaccinated in comparison to 89 deaths in the fully vaccinated, and 561 in those people who were partially vaccinated (single dose). Concern focuses on September when without masking, small cohorts, improved ventilation, testing, and a strong outbreak "you would expect a large number of children to be infected", said Dr.Tuite. 

Florida, pointed out Dr. Deonandan, saw a steep rise in children's hospitalization, along with a number of other southern American states, and it is quite possible that such a scenario could play out in Canada as well. He has general, simple, workable advice for best-practise in avoidance of infection: Vaccinate ... wear masks indoors until a significant drop in case numbers, (all the more so in situations where exposure to people whose vaccine status is unclear).

Registered nurse Linda Wright attends to a patient in the COVID-19 Intensive Care Unit at Surrey Memorial Hospital in Surrey, B.C., Friday, June 4, 2021. THE CANADIAN PRESS/Jonathan Hayward