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Unvaccinated people are more likely to catch COVID-19, but by how much? The answer has changed in recent months.

Montreal -

Unvaccinated people are statistically more likely to catch COVID-19, according to Santé Quebec. But by how much? The answer has changed in recent months, as efficacy wanes and variants emerge, among other factors.  

Quebec public health reported Friday that unvaccinated people are 3.8 times more likely to catch COVID-19 than those who are fully vaccinated.

While that’s still a significant jump in risk, it’s lower compared to months ago when the vaccine was still fresh in Quebecers’ arms. For example, on Aug. 25, unvaccinated people were 8.2 times more likely to get sick than those with two shots.

Still, the vaccine offers good protection against serious symptoms – as of Friday, unvaccinated people were 14.8 times more likely to wind up in hospital after getting sick.

But as cases ramp up again in Quebec, and the new Omicron coronavirus variant causes a worldwide stir, should people be worried about the vaccine’s apparently decreased protection?

“If you've gotten your two doses, and you are otherwise healthy, I think you can be relatively confident that you have good protection against COVID-19,” said Dr. Christopher Labos, a Montreal cardiologist with a degree in epidemiology.

"There is waning efficacy to vaccines," he continued. "They are still highly effective, but with time, as people get further and further away from their second dose, vaccine efficacy does decrease a little bit."

There are a number of factors that play into how protective a vaccine is, Labos said. For example, different demographics are at different levels of risk, each group bares different vaccination rates, and the Delta variant has changed how quickly the virus can spread

Still, for any number of reasons, the coronavirus is spiking in Quebec. Despite the fact that eight in 10 Quebecers aged 5 and up are fully vaccinated, “the pandemic is not over,” Labos said.


A new variant is spreading quickly through southern Africa, prompting Canadian officials to halt travellers from affected regions from entering Canada.

As of Friday, there were no recorded cases of the new variant in Canada, but that could change.

Canada’s Chief Public Health Officer, Dr. Theresa Tam said on Friday it’s going to be “very difficult” to keep the mutation out of Canada “entirely,” but that screening and isolation measures are already being put in place at the border.

“The border is never 100 per cent, but each layer provides an additional layer of protection,” she said.

So, what should Quebec do to prepare, should the variant arrive?

“I don't think it's anything that should be affecting our course of action right now,” Labos said.

While Quebecers might be tired of hearing it, Labos says the best thing to do remains the same: wear a mask, keep your distance, and get vaccinated, if you haven’t already.


If time is a determining factor in vaccine efficacy, could Quebec start rolling out third doses to better protect its residents?

Yes and no, according to Labos.

While the province has already begun offering booster shots to certain groups, such as people with compromised immune systems, Labos says opening that up to the general population might not be the best course of action.

“You do see a boost in your antibody levels after you get a booster. There's very little controversy there,” he said. “The point, though, is that you don't want to give boosters where they're not going to be effective.”

“When you have a finite resource, like vaccine doses are, we also get a lot of benefit from vaccinating people in other countries,” he said.

In South Africa, where the new Omicron variant was discovered, just 24 per cent of residents are fully vaccinated. In Zimbabwe, another area from which travellers are being turned away, it’s just 18 per cent. In Mozambique, just one in 10 residents are fully protected.

“If we could vaccinate everyone, in all of these countries, new variants would stop emerging,” said Labos.

At the moment, Canada does donate hundreds of thousands of doses to countries where vaccination rates are lower.

A breakdown of where those vaccines are going can be found here.

“When you look at the situation globally, you clearly derive more benefit when you give somebody their first dose compared to when you give somebody their third dose,” Labos continued.

“We have to stop thinking of this as a Canadian problem or a Quebec problem and really look at this as a global problem.” Top Stories

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