Race between vaccines and variants is back on as B.1.617 takes hold in Canada
Prioritizing 1st shots leaves us vulnerable to B.1.617, but vaccination rollout is ramping up
This is an excerpt from Second Opinion, a weekly roundup of health and medical science news emailed to subscribers every Saturday morning. If you haven't subscribed yet, you can do that by clicking here.
A new coronavirus variant is taking hold in Canada, leaving experts divided over whether it will expose the weaknesses in our strategy to prioritize first doses of COVID-19 vaccines and jeopardize reopening in much of the country.
Some worry that's the case, but with Canada's vaccine supply ramping up and second doses accelerating across the country, others believe fears over B.1.617 may be overblown.
So how at risk are we from B.1.617, the variant first identified in India also known as delta, and how concerned should Canadians be as we inch closer to reopening much of the country?
That depends on who you ask and the uncertainty the next few weeks hold. But there's no doubt we're in a much better place than we were when B.1.1.7, the variant first identified in the United Kingdom also known as alpha, hit Canada hard at the beginning of this year.
"I'm taking it very seriously, it's a variant of concern for a reason. It's clearly more transmissible," said Dr. Isaac Bogoch, an infectious diseases physician and member of Ontario's COVID-19 vaccine task force.
"There are a lot of similarities in how this is taking over to be the dominant variant, much like we saw B.1.1.7 do several months ago. So you can't ignore this, it's something that warrants close attention."
But Bogoch hasn't lost hope that the pace of our vaccine rollout and the protection the shots provide could avert potential disaster — even if research shows one dose of the Pfizer-BioNTech and AstraZeneca vaccines are only about 30 per cent effective against it.
New data from Public Health England is also discouraging, finding that two doses are more effective than one against B.1.617 and that not only is it more transmissible but it also appears to cause more significant illness as well.
"All this tells me is that we need to really work on getting second doses out faster, especially among vulnerable populations," he said.
"But if this is a race between the variants and the vaccine — the vaccine is going to win this round in Canada."
Prioritizing first doses could 'fall flat' with B.1.617
The U.K.'s reopening strategy is in jeopardy as it battles a rise in B.1.617 cases, mostly among unvaccinated individuals and those with one dose, raising fears that Canada's decision to delay second doses by up to four months could leave us more vulnerable.
"This is really the big risk with the one dose strategy," said Angela Rasmussen, a virologist at the Vaccine and Infectious Disease Organization in Saskatoon.
"The real issue here is making sure that since it is more transmissible, that you have as many people with as much immunity as possible and this is where the delayed second dose strategy can fall flat."
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Rasmussen has been critical of both the U.K. and Canada's delayed dose approach due to a lack of concrete data to support it, but the move has provided partial protection to millions of Canadians and helped control our third wave at a time when vaccine supply was low.
She says because B.1.617 is more contagious — either because infected individuals can expel more infectious virus particles, or it takes fewer of those particles to infect others, or both — it's important to prioritize second doses in vulnerable Canadians now.
"If you have a variant that's more transmissible, more people are going to get it," she said. "Which means that more people are going to end up very sick from it and more people are going to die from it."
Canada lacks 'clear view' of B.1.617
One advantage we had with B.1.1.7 that we don't with B.1.617 was that it was easy to screen for it due to a lucky break — a simple genetic marker that appeared on test samples called an S Gene failure that signalled the variant was likely present.
But with B.1.617 we're not so lucky, and experts say we could be flying blind as cases may be rapidly growing behind the scenes in Canada due to a lack of surveillance.
"We don't have the ability to see it as well as when we're screening for B.1.1.7, because we don't have that quick screening test," said Prof. Ashleigh Tuite, an infectious diseases epidemiologist and assistant professor at the University of Toronto's Dalla Lana School of Public Health.
Tuite says researchers have been forced to try to calculate the spread of B.1.617 with "incomplete data," but there are early signs that an "unknown" variant is spreading in the background in Canada.
"All signs point to that being B.1.617, but we don't have a perfectly clear view on what's happening," she said. "The challenge right now is just understanding the extent of the issue and how geographically widespread it is right now."
A recent cluster of COVID-19 in Newfoundland & Labrador that has grown to at least 60 cases was confirmed as being caused by B.1.617, while outbreaks of the variant have also been detected in B.C., Quebec, Alberta and Ontario.
Troy Day, a member of the Ontario Modelling Consensus Table and a mathematician at Queen's University in Kingston, Ont., says B.1.617 will likely overtake B.1.1.7 to become the new dominant strain in Ontario by next month.
"The frequency of B.1.617 in Ontario is probably somewhere between 15 and 20 per cent at this stage," he said. "Within the next month or month and a half, Ontario-wide, the suggestion is it will probably be on the order of 80 per cent."
Day says B.1.617 has a transmissible advantage over B.1.1.7, much like the latter had over the original strain of the coronavirus, which could allow it to take over in parts of the country where it's already emerged, like Ontario and British Columbia.
"B.1.617 is not blowing up in any huge way at this stage yet, but it's not decreasing either," he said. "So it seems like we haven't yet got enough effective vaccination to keep that variant under control."
'Hugely different situation' with vaccines
Some experts say the concerns over B.1.617 threatening to jeopardize our reopening strategy or prompt another lockdown may be overblown, and that the current pace of vaccine rollout may be enough to control it.
"With the vaccines, it's a hugely different situation," said Dr. Sumon Chakrabarti, an infectious disease specialist at Trillium Health Partners in Mississauga.
"I'm not as worried about this being disruptive, what I am worried about though is that the response to this is going to be continuing to kick the can down the road in terms of reopening."
Chakrabarti says new variants will continue to emerge in the future, and we need to balance the fears about them with the context of our accelerating vaccine coverage in Canada for both first and second doses.
"In the new post-pandemic world, we're going to have outbreaks of these things and that doesn't mean that we necessarily need to stop reopening," he said. "I'm just worried that as more of these things come up, it's going to continue to slow down our plan."
One thing Chakrabarti says has gotten less attention in the media and on social media is that while one dose was found to be only about 30 per cent effective against B.1.617, they were still extremely effective at preventing hospitalization and death.
Rasmussen says there's no denying fully vaccinated people have much greater protection against the variant, but the larger threat from B.1.617 in Canada is to Canadians without even a single dose.
"If you've got the majority of the people in Canada vaccinated with two shots, we would not have a problem with variants spreading," she said. "Except potentially, among pockets of unvaccinated people."
Bogoch says that as supply ramps up, the threat of B.1.617 and other variants will likely become less and less about vaccine access and more about hesitancy and choice.
"People who ultimately choose not to get vaccinated will sadly be at high risk for getting this infection," he said. "Because this virus isn't going anywhere."
This is an excerpt from Second Opinion, a weekly roundup of health and medical science news emailed to subscribers every Saturday morning. If you haven't subscribed yet, you can do that by clicking here.
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