How concerned should you be about variants of concern in Quebec?

Quebec has fared well at warding off the most talked-about variant of the summer, delta, thanks to stringent measures over the winter and a steadily growing vaccination rate. 

But experts warn the variant's presence in the province is likely to spread in the coming months, and that other variants could gain prominence as their foothold grows and Quebec further loosens restrictions.

They say two doses of a COVID-19 vaccine continue to provide the best protection against the virus and its mutations, though breakthrough cases — when someone becomes infected despite being fully vaccinated — are taking place. 

"We do expect [delta] to increase, even though it's lagging behind what's happened in Ontario. So that's certainly the main one of concern at the moment, although we're keeping a a wide view for other variants as well," said Jesse Shapiro,  a dynamic evolutionary biologist at McGill University, who is also part of the COVID sequencing consortium at the McGill Genome Centre.

The delta variant represents about five per cent of new cases in Quebec, compared to nearly 90 per cent of new cases in Ontario. The variant has also been deemed responsible for a rise in cases in the United Kingdom, where public health measures have nearly all been lifted.

Benoit Barbeau, a virologist in the department of biological sciences at the Université du Québec à Montréal, said the measures imposed over the winter because of the significant rise in cases helped delay the spread of delta. 

"For example, public places imposing wearing a mask; restaurants being closed and other stringent measures reduced the likelihood of the virus spreading. And those measures were more stringent than other countries," Barbeau said, adding that Canada's stricter border controls also probably played a role. 

Shapiro agrees the stronger measures likely helped keep delta away, but says why its presence in Quebec remains so much lower than, for example, Ontario is "rather mysterious."

"You know, a lot of COVID-19 infections do come down to sort of randomness," Shapiro said Monday morning, noting why some gatherings become super spreader events and others don't contributes to that randomness. Avoiding those kinds of events altogether, though, reduces the likelihood that the virus will spread. 

Monday afternoon, Quebec announced it was relaxing measures for large events. As of Aug. 1, the number of people allowed at an indoor concert will go from 3,500 to 7,500, divided by sections of 500. Outdoors, events such as festivals will be able to welcome up to 15,000, up from 5,000. 

Ceremonies, places of worship, conferences and sporting events with pre-determined seating will go from a maximum of 250 to 500 people outdoors and up to 250 indoors.

Last week, Tourism Minister Caroline Proulx announced the province would be testing measures at two large-scale events in the fall with a view to once again welcoming large international audiences at festivals. Some experts said, with delta lingering in the background, the decision felt premature. 

Proulx said those events would be cancelled if Quebec sees a surge in cases. 

A new variant being studied in Quebec

Shapiro and other scientists in Quebec have been studying the presence of another variant in the province, which is so far called A.2.5 and has not yet been classified a variant of concern, like delta is. 

"There's not yet any evidence that it's more transmissible or that it escapes immunity," Shapiro said of A.2.5. 

"But it's nevertheless one that we are tracking with interest. And the reason for that is it was it popped out because it has accumulated quite a lot of mutations in a relatively short period of time."

Shapiro said a high number of mutations is what alerted scientists to another variant, the alpha variant, which was first detected in the U.K. late last year.

Both Shapiro and Barbeau say a third dose of COVID-19 vaccines or a booster shot may help in further preventing the spread of variants as no vaccine currently offers 100 per cent efficiency against the virus. They say that means some fully vaccinated people could end up in hospital, although those cases are still rare. 

"We're quite sure that delta is a problem," Shapiro said. "Booster shots could be developed for it, but it's not recommended [by Health Canada] yet."

A study recently published in the New England Journal of Medicine found that two doses of Pfizer's shot was 88 per cent effective at preventing symptomatic disease from the delta variant, compared to 93.7 per cent effective against the alpha variant, broadly the same as previously reported.

And that two shots of the AstraZeneca vaccine were 67 per cent effective against the delta variant, up from 60 per cent originally reported, and 74.5 per cent effective against the alpha variant, compared to an original estimate of 66 per cent effectiveness.

Shapiro said the best scientists can do at the moment is be ready to react quickly when a new variant of concern springs up.

"It's hard to predict what the next thing is or what's going to be a constellation of mutations that will replace the current one," he said.