Because research suggests that COVID-19 has infected about half of the Canadian population, the appearance of an even more contagious version of the virus means some people may be in another round.
But questions remain about the prevalence of reinfection and the short- and long-term health impact that subsequent cases of the virus could have.
With cases on the rise, here’s what the experts said about the emerging evidence of reinfections.
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What is the probability of reinfections?
The appearance of the Omicron variant caused a tsunami of infections that saw the proportion of the population with antibodies against the virus increase from 7% to 45% between December 2021 and May 2022, according to a published analysis by COVID-19 of Canada. Immunity working group this month.
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Working group co-chair Catherine Hankins said the jury is still pending the likelihood that this previously infected population will catch the virus again, mostly because Omicron’s BA.5 subvariant is fueling a summer hike.
“All we know is that it can happen,” said Hankins, a professor at McGill University. “This particular variant is really able to evade immunity, including immunity to its … previous subvariant.”
Prabhat Jha, a professor of epidemiology at the Dalla Lana School of Public Health at the University of Toronto, said the first hopes were that Omicron would act as a “benign natural enhancer,” that it would spread quickly, but that it would only cause mild symptoms. , were not confirmed.
“As more evidence accumulates, it suggests that Omicron is not the great protector we all thought it would be,” he said, citing data from the UK.
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Lynora Saxinger, a professor in the Department of Medicine at the University of Alberta, said BA.5 is different enough from previous strains because the immunity accumulated by a case of an earlier variant may not prevent infection.
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“It’s not impossible to get infected again,” he said.
What protection do you get from “hybrid immunity”?
People who have been vaccinated and infected should be strengthened by a “hybrid immunity,” Hankins said. But signs that some people are reinfecting themselves with COVID-19 shortly after a previous fight indicate any natural immune boost would be short-lived, he said.
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“People really shouldn’t think it’s done and dusted off. They understand it, and that’s it,” Hankins said. “You’ll get it back if you keep exposing yourself.”
Saxinger said BA.5 may be even more adept at breaking hybrid protection, but at this point, it’s rare for people who have had Omicron to be reinfected by one of their relatives.
“The combination of vaccination and relatively recent infection? It’s not terrible against (BA.4 or BA.5), especially if you don’t have any risk factors.”
Canadian studies have shown that people with three COVID-19 vaccines and one infection have the highest level of antibodies, Jha said.
However, he stressed that people who have been infected can benefit from another vaccine against COVID-19.
“The evidence says very clearly that having a natural infection to protect yourself is really risky. We knew that from the beginning,” he said. “The best protection is at least three doses of the vaccine.”
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How does reinfection affect the severity of the disease?
Hankins said it’s hard to keep track of whether people, on average, get sick the second or third time they get COVID-19.
“It seems to vary a lot depending on people,” he said. “The general expectation would be that you weren’t so sick the second time, but we’re seeing it all.”
While governments report a high number of people in the hospital, some of whom have had the virus before, it may seem to suggest that reinfection leads to more serious illnesses, Saxinger said, this is not necessarily the case. . Is that there are more cases of COVID in general.
“It’s really a function of the large transmission volume where we start to see increases in serious results,” he said. “But on a per-person level, the risk of a serious outcome still seems to be pretty low, especially if you’ve had a combination of being fully vaccinated and also previously infected.”
Jha said this is another area where more study is needed.
“But in theory, I have no doubt that having multiple infections is not good for you,” he said.
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“Some cavalry people say,‘ I’ll just get infected a few times, and then I’ll be fine, ’” he added.
It is also unclear, he said, whether reinfection increases the likelihood of contracting COVID in the long term.
“There’s a suggestion that multiple infections can contribute to longer symptoms. But again, that’s something we don’t know enough about.”
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What should we do?
“Everyone wants a quick response and says,‘ Okay, I want to know what to do. And I want to leave it behind, “Jha said.” But the virus works according to its own schedule. “
“Our immune system is trying to keep up with a mutant virus … And we basically have to be sensitive.”
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Increasing the absorption of the third dose is key to protecting people from reinfections, he said. Each vaccine you receive reduces the severity of the disease.
National data show that only 56 per cent of Canadians aged 12 and over have at least three doses of a COVID-19 vaccine, compared to about 90 per cent who have two doses.
Hankins agreed that getting a third shot is crucial.
“This is a highly infectious agent, but the more immunity you have on board, the better,” he said.
© 2022 The Canadian Press