Why the delta variant means some Canadians now more 'at risk' from COVID-19 than ever before

For fully vaccinated Canadians, normal life now feels within reach.

But for those still waitingfor a second dose or skipping their COVID-19 shots entirely this stretch may be among the most perilous points of the pandemic.

That's because the months ahead are a transition period, unlike anything we've experienced yet. The good news: case counts are nearing rock-bottom even as restrictions are lifting. Still, the fast-spreading delta variant keeps sparking outbreaks and infecting those who aren't yet vaccinated.

"We're testing new waters in a way; this virus hasn't seen a reopened population," said epidemiologist Caroline Colijn, a Canada 150 Research Chair in Mathematics for Evolution, Infection and Public Health at Simon Fraser University.

"People who are not vaccinated are going to be at a hugely increased risk in the coming months."

That's putting the country at a crossroads.Many Canadians have never been more protected. Others have never been more at risk.

So how do we all navigate this tenuous stretch ahead?

Experts, from infectious diseases specialists to epidemiologists, tend to agree that getting more people fully vaccinated is key to keeping delta at bayand ensuring the variant doesn't further exacerbateinequalities seen throughout the pandemic.

"We vaccinate everyone, we get the severity lower ... then people who haven't been vaccinated, they're at risk," Colijn said. "At a certain level, there's not a lot more to do."

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Delta a 'heat-seeking missile' targeting unvaccinated

Like other countries, Canada has been grappling with the rise of the delta variant, thought to be significantly more contagious than the early strain of SARS-CoV-2.

"As delta spreads rapidly, it's acting like a heat-seeking missile targeting those who haven't yet been vaccinated," warned Dr. Tom Frieden, the former director of the U.S. Centers for Disease Control and Prevention, in a social media post in late June.

Thankfully, the overall level of protection in Canada is now far higher than many other regions of the world.

With close to 40 per cent of Canadians fully vaccinated, and nearly 70 per cent having at least one dose, case counts have dropped to a seven-day average of less than 500 new daily cases across the country.

Public health data also shows COVID-19 infections following full vaccination remain extremely rare, representing just 0.5 per cent of the known COVID-19 cases reported since the country's vaccine rollout started in December.

And a recent Canadian study on vaccine effectiveness which is published online, but not yet peer-reviewed has echoed earlier global data from countries like Israel, suggesting leading vaccines offer high protection levels against severe illness.

"All the vaccines were quite effective against all the circulating strains that we've been seeing against both symptomatic infection, as well as severe outcomes, meaning hospitalization or death," said researcher and physician-epidemiologist Dr. Jeff Kwong, who works with both the University of Toronto and the Institute for Clinical Evaluative Sciences.

The Pfizer-BioNTech, AstraZeneca-Oxford and Moderna vaccines all worked best after two doses, the research team found, based on a study using linked population-wide vaccination, laboratory testingand health administrative databases in Ontario.

Regions relaxrestrictions as delta spreads

It's no surprise, then, that many Canadians are breathing a collective sigh of reliefand embracing a two-shot summer.

Public health officials and policy makers at all levels are loosening up as well, from multiple provinces slowly lifting lockdown restrictions, to Calgary's city council repealing its mask bylaw, to the federal government relaxing border quarantines for fully vaccinated Canadians.

Yet those moves are happening as unvaccinated residents millions of people sprinkled throughout the country remain at risk.

Many of those are children under 12 who aren't yet eligible for a jab, but are also far less likely to experience severe health outcomes from COVID-19. Some are staunchly anti-vaccineand unlikely to be swayed by public health messaging. Others are hesitant, or struggling to book an appointment, or wary of the medical system based on past experiences of racism or mistreatment.

Experts warn that as Canada continues reopening, providing delta more opportunities to transmit, those pockets of unvaccinated individuals act as kindling to a flame.

Yukon experiencing spike in cases

Anunprecedented spike in cases in heavily vaccinated Yukon offers one case study, noted epidemiologist David Fisman, a professor with the University of Toronto's Dalla Lana School of Public Health.

While there have been no confirmed cases of the delta variant in the territory so far, thegamma varianthas been spreading widely, sending more than 30 people to hospital and causing three deaths in just a month more than the territory experienced in all of 2020 despite more than 66 per cent of the population being fully vaccinated.

"It's amplifying in child-care settings, where those little kids aren't going to be vaccinated, and then it's moving around and hitting the adults and it is causing deaths and it is causing hospitalization," he said.

"Those are overwhelmingly in a non-vaccinated part of the population."

Alarm bells are also ringing in Los Angeles following California's reopening, despite the latest available data showing COVID-19 case counts and hospitalizations among most groups have been dropping dramatically.

But for Black residents, who are less likely to be vaccinated than the city's other racial and ethnic groups, the hospitalization rate actually grew by 11 per cent between mid-May and mid-June, the Los Angeles Times reported.

According to Fisman, those who were least at risk to start with are also the ones most likely to get vaccinated.

"So I think what we are going to see is possibly exacerbation of some of those inequalities that we've already seen."

On a broader scale, numerous countries with limited access to vaccines, including many African nations with less than two per cent of the continent's 1.3 billion people gettingeven one dose of a vaccineso far are now grappling with outbreaks and deaths tied to delta, amid fears the local epidemics could turn even more dire.

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Experts warn of ripple effect from outbreaks

Colijn is hopeful Canada will have a different outcome, even as this variant keeps spreading while the country reopens.

"We're likely to see quite a lot of infection," she said, "but hopefully not a lot of hospitalization and death."

What's crucial now, several experts told CBC News, is ensuring vaccines reach every Canadian who wants a shot, otherwise delta-driven outbreaks could have a ripple effect on the lives of even fully vaccinated residents.

"We have communal health resources, and if you knock down the health-care system, it's everybody's health-care system that gets knocked down," stressed Fisman. "It's not like you have selective knocking down of health resources that would be allocated to unvaccinated people."

Raywat Deonandan, an epidemiologist and professor at the University of Ottawa, said it's unlikely that hospital networks would become overwhelmed at this point in the pandemic.

But he noted that even milder infections can have long-lasting health impacts on individuals, prompting a need for all eligible adults and eventually children to get fully immunized as quickly as possible.

Otherwise, he warned, Canada could be forced to return to stronger measures to combat rolling outbreaks for months to come.

"That's not the outcome people want."