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What you need to know about the subvariant now driving a seventh wave in Ontario

Ontario is now in a seventh wave of the pandemic and it is being driven by the BA.5 subvariant.

The newest mutation involving the Omicron variant has brought about a rapid rise in cases in Ontario and renewed concerns about the possible revival of public health measures.

Here is what you need to know about BA.5 and Ontario’s latest wave:

So what exactly is the BA.5 subvariant?

The subvariant was first detected by scientists in South Africa in January and has been formally tracked by the Wold Health Organization since April. It has already driven a resurgence in viral activity in a number of countries, including Portugal, the United Kingdom and the United States. The good news is that it not believed to cause more severe illness than earlier strains of Omicron but it could be more infectious. In Ontario, the percentage of samples identified as BA.5 following whole genome sequencing has risen from 14.8 per cent at this time last month to approximately 66 per cent as of July 6 and it is now being blamed for bringing about Ontario’s first summer wave since the onset of the pandemic.

“I think that the fact that it's quickly become dominant is a way to show how infectious it is,” Dr. Karen Born, who is the assistant scientific director of Ontario’s Science Advisory Table, told this week. “We are learning more about BA.5 every day, there is just a huge volume of studies going on about it but the early studies do show that it replicates more quickly as compared to prior strains and it replicates more quickly in the body as well, making it very efficient and much more contagious.”

What is it doing to transmission?

Most experts agree that Ontario is now in a seventh wave of the pandemic driven by the BA.5 subvariant. The science table has said that the wave likely began on June 17, though there is no real consensus on when it might peak. The number of people hospitalized with COVID-19 over the last month has risen by about 52 per cent and now stands at 712, according to the latest data released by the Ministry of Health on July 7. However, the burden on the healthcare system is nowhere near what it was during the initial Omicron wave in January when more than 4,000 patients were hospitalized with COVID-19. Most experts agree that Ontario is unlikely to see thousands of COVID positive individuals in hospitals during this wave but there are concerns about how well-equipped the healthcare system is to respond to even a moderate uptick in patient volumes.

"It is anticipated that the demands on this system from this COVID-19 wave will not be as high as some of the earlier waves but nevertheless it's hitting a healthcare system that is weakened by two years of the pandemic and a backlog of care needs," Born told, adding “So, you know, the system is potentially at a time where it lacks the capacity for, you know, a huge wave of increased demand.”

Do existing vaccines still work against BA.5?

Yes and no. Scientists have pointed to several mutations in BA.5 that could help it evade the body’s immune response, either from vaccination or a prior infection. This could account for some of the increased transmissibility associated with the virus, experts say. There was also a study published this week which found that vaccination or recovery from a COVID-19 infection prior to 2022 now provides little or no protection from getting infected again in the Omicron era. Vaccination, however, is still believed to be extremely effective against hospitalization and death, even in the era of BA.5.

“Basically what it does is it just chips away at some of the protective immunity we might have gained from vaccination or from recovery from infection, such that people are prone to infection or reinfection, even in those who were vaccinated or who have been infected in the past,” infectious disease specialist Dr. Isaac Bogoch told this week. “That doesn't mean everyone's going to get infected. That doesn't mean we're back to square one by any means. It just means that one component of the immune system, the antibody response, doesn't protect us as well as we were once protected in terms of getting this infection.”

What about rapid tests?

Ontario’s Chief Medical Officer of Health Dr. Kieran Moore said this week that the later Omicron variants, including BA.5, have impacted the sensitivity of a standard rapid antigen test, reducing sensitivity to 50 to 60 per cent. Moore said you can assume you have COVID-19 if you test positive, but one negative test isn’t enough to conclude you are COVID-free.

If BA.5 is so different why hasn’t it been classified as a variant of concern?

There have now been five subvariants in the Omicron era and despite notable genetic mutations that make each subsequent one a little different, Bogoch said that they do appear to all “fall under the same umbrella.” He said he has heard some people “grumbling that BA.5 is pretty far removed from BA.1 and BA.2” but doesn’t believe how the virus is classified matters hugely.

“There are some subtle nuances associated with BA.5 that make it different from other ones. But really the public health message is still the same. Nothing has changed in terms of how to best protect yourself and those around you from the virus,” he said.

Who is most at risk from a BA.5 infection?

Bogoch said that the experience of other countries suggests it is the same people who have been at-risk throughout the pandemic, specifically older Ontarians and people with underlying health conditions. But he said that there is also an increased risk factor for individuals who are not fully up to date on their vaccinations. That could, of course, be a problem in Toronto where only about 54 per cent of eligible residents have received a third dose.

“I think that there are some misconceptions that members of the public have where it is like ‘I've had COVID, I had COVID in 2020 and I'm not going to get it again.’ That's just not true,” Bogoch told

Could this wave end up resulting in some public health restrictions being revived?

Dr. Moore told reporters this week that he is not “considering recommending to the government any further public health measures” right now. He said that if BA.5 results in a spike in transmission to the point that the province’s healthcare system is threatened he would act but doesn’t anticipate having to do so. Bogoch, meanwhile, told that the threat posed by BA.5 can be better addressed through “honest and effective” communication with the public rather than legislation.

“We talk about communication to help drive positive human behavior. But that doesn't mean a press conference at 3 p.m. in the afternoon saying ‘hey everyone, this is a wave, put on your mask.’ You actually have to have a dedicated communications strategy and build trust in communities,” he said. “We talk about this like it is just virology and public health and medicine but is not. If you really want to create safer communities and protect Canadians better, it really involves utilizing the expertise of the social scientists and having meaningful community outreach and meaningful communication strategies because a lot of this is ensuring people take the steps that they need to do to protect themselves and those around them.”

Will a BA.5-specific vaccine be approved?

Several manufacturers have been racing to develop new vaccines that are more specifically targeted at the Omicron variant. Moderna is believed to be finalizing the regulatory submissions for its bivalent vaccine, which combines a portion of the original mRNA formula with a new updated version designed to better neutralize Omicron. Clinical trial data released last month revealed that the vaccine is more effective against BA.5 than its currently approved booster shot. However, the data showed a diminished immune response against BA.5 compared to BA.1. Speaking with reporters this week, Moore said that Ontario anticipates having access to updated vaccines in the fall but is still seeking “clarity” on “what will be the components of the fall vaccine.”

“If it is going to be BA.4 or BA.5 (specific) I anticipate they will have to ramp up production and it might be somewhat delayed, so maybe November or December,” he said. Top Stories

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