The province says the decision was made due to obscurity over future supply, not safety.
Given the sheer volume of mRNA vaccines funneling into the country, Alberta says it will use its remaining 8,400 AstraZeneca doses as second shots — rather than add to the list of first-dose recipients waiting for a second.
Ontario followed suit Tuesday afternoon, announcing it would be pausing the use of the shot. However, the province said the decision was made due to safety and supply related issues.
For now, this makes sense, said Dr. Isaac Bogoch, an infectious disease specialist based out of Toronto General Hospital.
“Why would you start doling out the remainder of vaccines when you don’t really know how much you’re going to get and when you’re going to get it next?” he said.
“It makes sense to reserve remaining AstraZeneca for second doses. Even then, it’s very likely that the data from the U.K. is going to demonstrate that mixing vaccines is safe and effective.”
But new safety concerns linked to the AstraZeneca vaccine are impossible to ignore — nor should they be, said Bogoch.
While not explicitly part of Alberta’s reason to stop initial AstraZeneca inoculations, Bogoch acknowledged that it might be difficult for Canadians to untangle yet another change with the vaccine from the waterfall of other developments in recent months.
Shots from AstraZeneca and Johnson & Johnson — viral vector vaccines — are linked to the very rare blood clot condition, whereas shots by Pfizer and Moderna — mRNA vaccines — are not.
“You can have sound policy, based on science and reason, but if you don’t communicate it effectively, it can cause significant problems,” he said.
Some medical experts now say that the use of AstraZeneca needs to be revisited, as the context of the vaccine continues to evolve.
For many months, the message from public health figures and politicians alike has been: Take the first shot you are offered.
But last week, the National Advisory Committee on Immunization (NACI) sparked controversy when it said Canadians who aren’t at high risk from COVID-19 may want to wait until a dose of an mRNA vaccine is available.
The chair of NACI has since said, however, that those who already received a dose of AstraZeneca shouldn’t feel like they made a poor choice.
Anna Banerji, an infectious disease specialist at the University of Toronto, said with so much hesitancy around this vaccine, it’s possible in the future that Canada could forgo the shot — but only if it has adequate and consistent supplies of Pfizer and Moderna.
She said she’s not surprised Alberta made the decision it did. But the roles could reverse, she warned.
“If we don’t have enough Pfizer or Moderna, then I think we have no choice but to use AstraZeneca,” she said. “It depends on supply-demand.”
Colin Furness, an infection control epidemiologist and assistant professor at the University of Toronto, isn’t a fan of Alberta’s decision.
“It slows down vaccination. Any slowdown, however temporary, is likely to be far more harmful than vaccine adverse reactions,” he said. “But opinion is dividing on the magnitude of the risk.”
Over the weekend, Dr. Andrew Morris, an infectious disease doctor at Toronto’s University Health Network, took to Twitter to share nuanced risk-benefit considerations when it comes to the shot.
“I want to emphasize again … if you cannot get mRNA to the very high risk, then AZ likely makes sense over no vaccine. Without question,” he tweeted.
He argues that offering AstraZeneca in places rife with COVID-19 cases — like Alberta, parts of Ontario and Manitoba — still makes sense and has significant benefits, but only if an ample supply of mRNA vaccines isn’t available, which isn’t the case anymore.
For the foreseeable future, the bulk of vaccines coming to Canada are Pfizer and Moderna.
Bogoch said Canada is still in the grips of a “true public health emergency” and having a tool like AstraZeneca at our disposal is still going to offer protection for yourself and others.
“Of course there’s a very rare, negative side effect associated with it, but it needs to be contextualized,” he said. “I think people that took it still made the right decision, but you have to enable people to make that informed decision by providing them with the true risk, the true benefit, and the true context.”
Ultimately, it is up to individual provinces and territories to decide how vaccines will be distributed.
Other provinces have noted that they too are monitoring vaccine developments closely. Ontario is among them.
“It’s an area we’re reviewing with our science experts at the tables, looking at the data and information around the so-called rare complications and how that impacts people,” Dr. David Williams, Ontario’s chief medical officer of health, said at a press conference Monday.
Supply vs. demand
The other issue on the table is one of supply.
Pfizer alone is expected to deliver two million doses a week through the month of May before increasing the weekly figure to 2.4 million in June. The steady supply has allowed most provinces to confidently expand the list of people eligible for vaccines over the coming weeks.
By contrast, the next shipments of AstraZeneca remain unclear.
Federal officials have said another 650,000 doses are expected this month, and an additional million in June, but no precise dates have been given.
Despite the wavering support for the vaccine, Canada will continue to push to bring the AstraZeneca shots into the country, Intergovernmental Affairs Minister Dominic LeBlanc said Tuesday.
“Provincial health authorities will decide the way that they and their judgment see their vaccines best administered to their populations,” he said. “But it would be irresponsible for Canada to not pursue the 650,000 doses of AstraZeneca we expect to get in the coming weeks and the millions of additional doses we’ll get in the month of June.”
Nearly all the 2.3 million doses of AstraZeneca delivered so far have been used, meaning hundreds of thousands of Canadians have received their first dose with little assurance on when they’ll get their second.
Because of that, provinces like Ontario have said it’s “very likely” they’ll need to mix different vaccines together to meet second dose schedules for those who received a first shot of AstraZeneca.
Right now, NACI recommends two doses of the same vaccine, so it’s important to make sure that those who got a first dose of AstraZeneca can be provided a second dose, said Dr. Theresa Tam, Canada’s top doctor.
“At the same time, we’re following evolving science, including studies from the U.K., to provide the most up to date advice on whether a mixed dose schedule is an appropriate way to go,” she said.
“That would offer a choice, essentially, for those who received AstraZeneca as a first dose.”
Bogoch agrees that the imminent study results on mixing and matching vaccines will be one to watch, and could change the conversation around AstraZeneca quickly.
“There are several different reasons that stopping (AstraZeneca first doses) is a reasonable option … as long as it’s communicated effectively,” he said.
–With files from the Canadian Press and Global News’ Katherine Ward and Katherine Aylesworth