The BA.5 subvariant is fuelling another COVID wave

A highly transmissible variantof the coronavirus is spreading through Canada, driving another wave of infections,even among those who have recently recovered from COVID-19.

The Omicron subvariant BA.5, and to a lesser extent, BA.4, islargely behind the latest wave the seventh of the pandemic and the third since the arrival of Omicron.

Both have shown an ability to evade the protection offered by previous infection.

"The BA.5 subvariant has mutated to the extent that your body is not recognizing it and people are getting reinfected," said Dr. Fahad Razak, an internist at St. Michael's Hospital in Toronto and the scientific director of Ontario's COVID-19 Science Advisory Table.

"So you're seeing this additional surge start in Ontario, and now it's started in other parts of Canada as well."

The good news is that data emerging from countries where BA.4 and BA.5 have already taken hold, such as South Africa, suggest they are not more severe than previous Omicron subvariants or more likely to lead to hospitalizations.

Still, the sheer number of people likely to get sick (particularly those vulnerable to serious illness),coupled with the overtaxed emergency rooms in many parts of the country, is cause for concern, Razak said.

"Something that's a little bit less severe but infects a lot of people meansthat the total number of Canadians who get sickvery sick and potentially die can actually be higher," he said.

Razak pointed to a scientific analysis conducted for the Toronto Star, which found that since mid-2021, Omicron has been more deadly for Ontarians aged 60 and over than the previous two waves combined due to the high volume of infections.

Razak is now among a chorus of experts and public health officials urging the Canadian public to get a booster for protection against more serious illness.

"That third dose is incredibly valuable," he said. "It gives you protection against severe disease and will give you at least a few weeks, maybe a couple of months, for protection against even getting infected at all.

"So if you haven't received that third dose, there's no better time than now."

Keeping your vaccination 'up to date'

Canada had one of the highest vaccination rates in the world after two doses, but uptake on subsequent shots has been slower. Across Canada, more than 40 per cent of eligible Canadians havenot yet received a third dose.

Razak saysthe messaging around what constitutes being "fully vaccinated" needs to change,given the evolution of the virus and the waning immunity of the vaccines over time.

"Probably the better way of describing this is keeping your vaccines up to date, rather than being fully vaccinated, in the face of a virus that is mutating rapidly."

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Sarah Otto, an expert in modelling and evolutionary biology at the University of British Columbia, has been tracking the changes in the coronavirus and saysit has changed quickly.

BA.4 and BA.5 are likely to soon become the dominant strains across the country, she said.

These subvariants tend to infect upper airways, she said, and "not so deep into our lungs."

"That said, there is still a substantial death rate, especially if you've not had any immunity at all," Otto said.

She also recommends that those eligible for a third dose should get one as soon as possible, and older people or those more vulnerable to severe disease should get a fourth.

"Why play Russian roulette with your health and with the health of your loved ones? Get a booster if you can," she said. "That will protect yourself and protect those around you."

No restrictions forthcoming

This week, officials in Ontario, Quebec and British Columbia acknowledged that their provinces had entered into another COVID-19 wave.

In Quebec, the number of COVIDpatients in the province's hospitals climbed from 1,007, to just under 1,500 in the last month an increase of more than 50 per cent.

Hospitalizations are also climbing week over week inBritish Columbia, as well asin Ontario, where about 60 per cent of confirmed COVID-19 cases are the result of BA.5.

None of theprovinces said public health restrictions were forthcoming, at least not during the summer.

"We're no longer at the point of imposing things when people are well aware of the risks. It's just a question of reminding them," Quebec Health Minister Christian Dub said Thursday.

For now, it's up to the public to make informed choices, more than two years into the pandemic, saidCatherine Hankins, co-chair of Canada's COVID-19 Immunity Task Force and an epidemiology professor at McGill University,in an interview withCBC Montreal's Radio Noon.

"We're into a different scenario, with a highly transmissible virus and with no mandates really in place," she said. "We're at a tricky juncture."

For his part, Razak urged people to wear a mask if gathering inside inlarge groupsand to meet outside, when possible.

If cases rise again in fall, he said, the threshold for reintroducing mask mandate should be low.

"It's about using things like masks to prevent the more aggressive steps of restrictions or closures that were pursued earlier in the pandemic," he said.

And despite another uptick in cases, Razak said there are reasons to be hopeful.

"We have a large amount of immunity in our population now, which helps protect against severe disease," he said. "We have vaccines that continue to be remarkable,even though there's all these mutations occurring.[They] continue to be very protective against severe disease, if we use them."