Another wave of COVID-19 for Ontario? A concerning new variant is threatening to take hold, data shows
Behind Ontario's rapidly falling daily case counts lies a concerning pattern that suggests a new, more transmissible variant of COVID-19 is poised to take over from the one that fuelled the province's third wave, experts say.
The variant B.1.617, which was first isolated in India and has spread rapidly in the U.K., is thought to be up to 50 per cent more transmissible than B.1.1.7, the variant of concern that launched Wave 3 after starting to become dominant in January.
In recent weeks, Public Health Ontario data shows the percentage of cases testing positive on the province's variant-screening tests - which check for a gene found in B.1.1.7 but not for the one specific to B.1.617 - has dropped from a plateau of about 95 per cent in early May to about 85 per cent in the most recent data.
While this drop may seem like good news on its face, it suggests something else is muscling its way in.
B.1.617 is the most likely explanation, said Ashleigh Tuite, an epidemiologist at the University of Toronto's Dalla Lana School of Public Health.
It makes sense it would be replacing the other variants of concern because B.1.617 is likely more transmissible, Tuite said, noting that more-limited sequencing data from Public Health Ontario suggests the variant is here and growing.
So based on those individual pieces of data, none of which is necessarily a smoking gun, taken altogether suggests that what you're seeing is the replacement of circulating strains by B.1.617," she said.
Dr. Isaac Bogoch, infectious diseases specialist at University Health Network and associate professor at the University of Toronto, agreed, saying Ontario may be starting to see a redux" of the early days of Wave 3, when B.1.1.7 took over from the then-dominant, less transmissible variants.
Now, as we see a decline in B.1.1.7, what's filling the void is probably all B.1.617," Bogoch said. It's here. It's spreading. It's important to recognize and it just means that we've got to hustle on getting second doses of vaccines out."
New daily cases of COVID-19 are down considerably since mid-April, when the province reported a single-day high of 4,812 cases. On Tuesday, Ontario reported just 699 new cases, a declining trend that is likely to continue for the time being, even as the share of B.1.617 cases rises.
That's because while the new variant may be spreading faster than existing types, the data shows it's here in relatively low numbers for now.
The Star asked Public Health Ontario why it does not screen for the B.1.617 variant and if there were any plans to do so, but did not receive a response by press time.
Colin Furness, an infection control epidemiologist at the University of Toronto, said it's not a question of if, but rather when the new variant takes over. But to find out when exactly - whether it will become dominant by the end of the summer, or earlier - the province needs better data, he said.
My belief is that B.1.617 is going to be the story for the fall. And the question is, where are we with vaccinations? Because a fourth wave, if we have one, will be B.1.617 among people not yet vaccinated," Furness said, adding he is particularly concerned about what will happen with a return to in-person learning in September if children aren't yet vaccinated.
Vaccinations are great, but the fact of the matter is, if you get a really high viral dose, that's what puts you at risk," he said. Being up close to your kids is going to be risky for parents, grandparents and teachers for that matter. I think the sooner we can start vaccinating kids under 12, it won't be a moment too soon."
Another concern, said Dr. David Fisman, an epidemiologist at the Dalla Lana School of Public Health, is whether Ontario may be tempted to roll the dice" by moving to reopen too early, just like how reopening quickly after Wave 2 helped spark the third wave.
At that time, the province's COVID-19 Science Advisory Table was warning that the fall in overall infection rates after Wave 2 was giving a false sense of security. Underneath the drop, it said, the data was simultaneously showing a rapid, exponential rise in the variant B.1.1.7.
That variant, first isolated in the U.K., was such a concern because the data showed it to be more transmissible than the older versions of the virus that had been circulating in the province since early 2020. It could spread easily in situations existing variants of the virus could not - meaning the restrictions that otherwise suppressed Ontario's Wave 2 might still let B.1.1.7 run rampant in a frightening third wave, which is what happened.
What you see with B.1.617 is the same thing," Fisman said. What we see is this increasing market share ... it's growing about 20 to 40 per cent faster than B.1.1.7, and that's with schools closed."
On that note, Fisman said he disagrees with a recent statement from the science table - of which he is a member - that called for Ontario schools to start reopening on a regional basis. The risk of B.1.617 is too high at a time when Ontario intensive care units are still swamped with COVID-19 cases, he said, estimating the province needs another month to a month-and-a-half to get to the point where vaccination rates can mitigate the risk.
On Tuesday, the Star reported Premier Doug Ford is leaning strongly against reopening schools for the few remaining weeks before the summer break.
Bogoch, who is a member of the province's COVID-19 Vaccine Distribution Task Force, noted that early data from the U.K., where the government estimates that somewhere between half and three-quarters of all new cases are B.1.617, suggests existing COVID vaccines are protective and that two doses provide significantly more protection than one dose.
That means we really have to work hard to get our second doses in fast," he said, stressing people who are at greatest risk of having a severe outcome should be a priority.
He added that while the current focus for second doses is on people over the age of 80, the province has already been providing second doses to Indigenous communities, front-line health-care workers and those with underlying medical conditions, such as different types of cancers, organ transplant recipients and people with kidney disease on dialysis.
Kenyon Wallace is a Toronto-based investigative reporter for the Star. Follow him on Twitter: @KenyonWallace or reach him via email: kwallace@thestar.ca
Ed Tubb is an assignment editor and a contributor focused on crime and justice for the Star. He is based in Toronto. Follow him on Twitter: @edtubb