BA.5 expected to cause 70% of COVID cases by July 1

Researchers examining the threat of emerging strains of COVID-19 predict that Omicron BA.5 will account for nearly 70% of cases by Canada Day.

Modeling expert Sarah Otto of the Coronavirus Variants Rapid Response Network says the fast-spreading subvariant is poised to dominate infections across the country.

The University of British Columbia professor predicted a surge in July, peaking in August.

« The latest sequence data is from mid-June, but the projections for July 1 would be: about 13% (of cases are) BA.4 and 69% BA.5, » said Otto, co-lead of the computational biology. and the network modeling branch, also known as CoVaRR-Net.

« I refer to this as a third Omicron wave because I’ve lost count of all the other waves. »

The head of Ontario’s COVID-19 advisory group also suspected BA.5 to be the main driver nationally and pointed to several indicators that suggest it is already responsible for more than half of cases. reported in his province.

Dr Fahad Razak said the strain is particularly adept at evading immunity from vaccination and previous infection, leading to « a very rapid increase ».

A national breakdown of variants by the Public Health Agency of Canada recorded a dramatic jump earlier this month, with BA.5 responsible for 14.6% of COVID-19 cases identified by whole genome sequencing in the June 5, against 7.1% the previous week.

Quebec public health director Dr. Luc Boileau said Wednesday that BA.2.12.2 remains the dominant strain in that province, but BA.5 is gaining ground faster than the others. These two Omicron cousins, combined with BA.4, represent more than three quarters of Quebec infections.

Here is an overview of what we know about BA.5.


It appears to be no more or less severe than previous strains, Razak said, but several issues make it difficult to say whether a jump in BA.5-fueled cases will also affect hospitalizations.

He noted that the Canadian population now has a mix of two, three and four doses of vaccines – different vaccines were used depending on eligibility, and the timing of vaccinations varied, all of which affect the current situation of immunity. Meanwhile, the recent spike in infections has boosted immunity even further, with perhaps half or more of Canadians infected in the past six months.

« It’s very hard to know what happens when you have this sub-variant, which is mutated but still part of the Omicron family as it comes up. Will it trigger a new increase in hospitalizations? I think it’s very hard to say, » Razak said. .

Otto noted that BA.4 and BA.5 appear to primarily infect the upper respiratory tract – compared to the lower lungs – leading to less severe cases on average than the pre-Omicron variants.

« My prediction is that cases will go up, hospitalizations will go up, but my current hope is that it won’t be as bad as the BA.2 wave, » she said, adding that there was no not enough data. yet to know for sure.

At the rate BA.5 has grown, she said BA.5 is now about five times more common in Canada than BA.4.

“Very soon it will only be wave BA.5,” said Otto, also a member of the BC COVID-19 modeling group and an external modeling group from the Public Health Agency of Canada. Canada.


While Canadians have higher immunity than ever before, this new subvariant is radically different from what existed before, Razak said, making reinfection more likely.

« It’s mutated enough that even if you get infected with the original wave of Omicron that just passed in the spring, the surface of the virus looks different enough that your immune system doesn’t recognize it, and another infection reoccurs. «

Most fully vaccinated people infected with BA.5 experience a mild bout of COVID-19, Razak said, but high-risk groups, including immunocompromised people and the elderly, are still at greater risk of severe fallout. sick.

Even mild COVID-19 can be very disruptive, added Razak, who fell ill despite being triple vaccinated and struggled to work.

« I really didn’t feel like I was back to normal for three or four weeks. And I have many, many friends and colleagues who are in a similar risk category with a very low risk of hospitalization, but the infection has really affected us in terms of our our family lives, our professional lives,” he said.

Then there’s the threat of a long COVID-19, a still largely mysterious condition in which certain symptoms linger months later, such as fatigue, brain fog, shortness of breath and general pain, he said. -he declares.


The best thing an individual can do is get fully vaccinated, stay outside as much as possible when socializing or interacting with others, and wear a mask indoors as much as possible, said Razak.

« It’s no longer a black and white situation where it’s all or nothing. The public health measures, a lot of them have been lifted and so you really have to look at how you can as an individual reduce your risk, » Razak said. .

“And get vaccinated whenever possible, knowing that there is probably a new generation of vaccines, which are more suitable for Omicron and which offer better protection which will be available, potentially as early as the fall.”

Masks can play a role in mitigating the BA.5 hit, even though mask mandates have fallen in many circumstances, Otto said.

« The weather report is not great right now for COVID. And the weather is about to get bad and we have to act accordingly. »

Otto also said now was the time to get up to speed on vaccines, especially the elderly, many of whom were boosted in December and January and would have weak protection unless they received a fourth. dose.

“That would be my one very strong plea: anyone with a health sensitivity, anyone who is older, should receive the reminders that are available to them right now and for them to be protected in this wave that is coming,” a- she declared.


Vaccines in development are currently trying to match the strains currently in circulation, Razak said.

« More doses are in our future, » he said.

Razak says the version of the virus circulating now has mutated so much « it’s barely recognizable from what appeared two years ago. »

« It’s not a failure of the original vaccines. They were very effective for what they were supposed to do. They still protect you against serious diseases, it just means we were able to advance the science to give you something even better.”

In the meantime, Otto called on public health officials to be candid about what this summer could look like without continued measures to contain infections as cases rise.

“I think the public doesn’t know that the BA.5 wave is really upon us in Canada. Public health officials should make this much clearer. And they should encourage the public to step up the safeguards we all know work. – hide, (open) those windows, socialize outside. We should just be prepared. «


With files from Morgan Lowrie in Montreal. This report from The Canadian Press was first published on June 29, 2022


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