The decision to restrict the use of one of four approved vaccines at a time when COVID-19 levels are rising again in Canada's hardest hit provinces is a tough pill to swallow, but makes sense given the lack of data on a rare blood clot risk, experts say. (John Woods/The Canadian Press)

Why restricting AstraZeneca vaccines in Canada means balancing 'vaccine risk vs. disease risk'

Adam Miller

Canada's decision to suspend the use of the AstraZeneca-Oxford vaccine in Canadians under 55 during a surging third wave and a slow vaccination rollout is a calculated risk.

The National Advisory Committee on Immunization (NACI) updated its guidance to provinces and territories against the use of the vaccine for younger Canadians on Monday, following reports of rare but potentially fatal blood clots in Europe connected to the shot.

Health Canada says the benefits of the vaccine to protect against COVID-19 still outweigh the potential risks, with more than 300,000 doses of the shot administered and no cases of the serious clotting condition, known as vaccine-induced prothrombotic immune thrombocytopenia (VIPIT), in Canada. 

But the decision to restrict the use of one of four approved vaccines at a time when COVID-19 levels are rising again in Canada's hardest hit provinces is a tough pill to swallow for some.

"It can be a very powerful tool when we're at this stage of the pandemic where we're talking about, in hotspots at least, the system getting to a point of potential collapse," said Dr. Susy Hota, an infectious disease specialist at the University Health Network and an associate professor of medicine at the University of Toronto. 

"There are humans behind that story, and when you're in a hospital where you're seeing an exponential rise in the number of COVID-positive patients coming in, and your staff to help manage these patients is the same pool of staff — then those numbers aren't adding up."

But on an individual level, experts say the lack of data on the risk of VIPIT to Canadians from the AstraZeneca vaccine is concerning and NACI was right to err on the side of caution in order to avoid putting lives unnecessarily at risk. 
 

Pharmacist Abraam Rafael administers a COVID-19 vaccine to Maureen Doyle at his pharmacy in Toronto on March 14 as Ontario starts administering the AstraZeneca vaccine for COVID-19 to residents aged 60-64. (Cole Burston/The Canadian Press)

Race between vaccines and variants

Ontario has more ICU admissions than at any other point in the pandemic, B.C. has had its highest single-day number of new cases to date, and Quebec saw its biggest one-day spike in almost two months as more transmissible variants are spreading rapidly across Canada.

The good news is that vaccines work; eight provinces and territories reported no new deaths in a single day this week, and the decision to prioritize COVID-19 vaccines in long-term care has led to a dramatic drop in deaths in residents. 

The bad news is that the race between vaccines and variants is taking on new urgency; the majority of vulnerable Canadians are still unvaccinated and the third wave is hitting younger adults harder and showing no signs of slowing down. 

"It's so complicated, because I look at it as being two things: What is the absolute risk of this potentially related severe side effect versus the absolute risk of the disease?" said Dr. Lynora Saxinger, an infectious diseases physician and an associate professor at the University of Alberta faculty of medicine in Edmonton.

"The other consideration is, what is the public backlash to potential outcomes of any particular course of action?"

Health Canada says VIPIT occurs at a rate of about one in 100,000 people vaccinated, with a mortality rate of about 40 per cent, although more research is needed and that risk is reduced if treated early enough. But the total number of people in Europe who got the rare blood clots after vaccination is small — as of Thursday, dozens of cases have been reported compared to millions who received the shot.

But crucially, the people who appear to have an elevated risk of the rare blood clots are not the same age group most at risk from COVID-19.

"If you look at the average 30 or 40-year-old Canadian, their risk of getting severely ill from COVID based on our current experience is substantially less," said Dr. Andrew Morris, a professor of infectious diseases at the University of Toronto.

"You're asking them for the good of the country to take on a risk that they wouldn't even get with COVID. So why would you give them a vaccine that is more likely to give them harm then COVID is? It makes no sense."

Canada has had close to 23,000 COVID-19 deaths in the year since the pandemic began, but fewer than a thousand of those have been in people under 60 and just over 300 in Canadians under 50.

"What happens to NACI if they say that everything is fine, despite the European experience which really brings it into question, and then we have even one death in Canada from this?" said Morris. "NACI would be just absolutely raked over the coals."
 

'Vaccine risk versus disease risk'

Dr. David Fisman, an epidemiologist at the University of Toronto's Dalla Lana School of Public Health, said the debate over whether suspending the vaccine in younger Canadians was the right decision is due to a miscalculation of risks for that age group.

"I think what you see is a bit of wire crossing around vaccine risk versus disease risk," he said.

There is also a risk of clots from getting COVID-19, but that's conditional on getting the disease first, and there are other vaccines to protect against it, he said, rather than using a vaccine linked to adverse events in this age group.

"The adverse effect here is rather devastating," he said. "[VIPIT] seems to be killing about half the people who suffer these consequences, and is highly likely to cause permanent neurological damage in survivors."

"Given that these are young people working in healthcare, it is likely that vaccination is conferring damage or death that they would not have suffered otherwise."

Dr. Menaka Pai, a clinical hematologist at McMaster University and a member of Ontario's COVID-19 Science Advisory Table, says the risks associated with VIPIT in younger adults are dangerous enough to warrant halting its use in those under 55.

"The clots that we see with VIPIT — they're serious. If you're not aware of them they can be hard to diagnose, they can be hard to treat," she said. 

"If you're older and likely to experience all the other horrible things that COVID does, including killing you, then your decision about urgency and needing any vaccine frankly is really different from somebody who is younger and probably better able to weather the storms of COVID." 

Pai says critics of NACI's decision are inaccurately drawing comparisons with the risk of VIPIT to the risk of birth control pills, which also carry an increased risk of blood clots.

"The reality is that every year a little under one in 3,000 women will get a blood clot on the combined oral contraceptive pill and every year one in 300 pregnant women will get a blood clot," she said. 

"But the clots that you get on those hormones are very different from the clots that we're seeing related to the AstraZeneca vaccine." 

Raywat Deonandan, an epidemiologist and associate professor at the University of Ottawa, says if the risk from the AstraZeneca-Oxford vaccine to younger Canadians can be mitigated with another COVID-19 shot, then the decision to halt the use of it makes sense.

"This is not the same as going to a place like Brazil where the disease is rampaging out of control," he said. 

"Whereas this is the only vaccine you have available to you — take it now or I can't guarantee you will be alive in a month. It's a different scenario entirely." 

But Deonandan says he can sympathize with critics of NACI's recommendations to suspend the vaccine because of the damage the decision may do to the public perception of COVID-19 vaccine safety overall. 

"If you are saving any lives, you're saving one or two lives [from VIPIT]," he said.  "On the other hand, you're creating such distrust of the vaccine you may be causing hundreds, possibly thousands of deaths from people not taking the vaccine." 

"But given what NACI's job is, which is to advise how best to deploy vaccines, they used the best evidence and came upon the right decision for their mandate." 
 

More than half of Canadians report increased stress during the pandemic — and it's the kind of chronic and unpredictable stress that tends to leave people unfocussed and unproductive. (Shutterstock)

This is your brain on pandemic: What chronic stress is doing to us

Back in the 1980s, there was a public service announcement on TV that you may remember — or may have seen on YouTube.

A guy in a kitchen held up an egg and said, "This is your brain." Then he cracked the egg into a hot frying pan, and said, "This is your brain on drugs."

One year into this pandemic, your brain might be feeling a bit like that egg: Fried.

"Everything is so much harder," said Stephanie Johnson, a client relationship executive who lives in Toronto. "I don't have the motivation that I used to have. I don't have the efficiency that I used to have."

"Defeated" is how Vas Smountas, a freelance graphic designer, describes it. Also living in Toronto, she describes herself these days as "tired, defeated, foggy, unmotivated."

And research suggests those feelings are not uncommon right now, as the chronic stress of the pandemic has both affected our brains — and robbed us of normal, healthy ways to cope.

Read more from CBC News' Stephanie Hogan on why a year of 'daily, unpredictable, malignant stress' can actually affect our brain tissue.

A health worker prepares to administer the AstraZeneca vaccine in Pristina, Kosovo, on March 29. (Laura Hasani/Reuters)

AstraZeneca-Oxford's COVID-19 vaccine safety questions answered

The recommendation to pause AstraZeneca-Oxford COVID-19 vaccinations among Canadians under age 55 over concerns the vaccine is linked to a rare blood clotting condition has prompted questions. Here are some answers.

Health Canada is requiring AstraZeneca and Verity Pharmaceuticals/Serum Institute of India, maker of the Covishield version of the vaccine, to take a detailed look at the benefits and risks of their vaccines by age and sex as part of the regulator's evaluation of rare blood clotting events following vaccination. 

Dr. Theresa Tam, Canada's chief public health officer, said on Tuesday that all chief medical officers of health across the country agreed to the pause as a precaution. 

"While the data is being gathered, we amassed experts from Canada but also had experts from Germany providing [their] first-hand interpretation of what this clotting with low platelets entity is like and some of the underlying scientific explanations," Tam said. 

"Canadians should be reassured that we have systems in place to detect safety signals and then analyze them." 

Read more from CBC Health's Amina Zafar on how clotting, platelets and AstraZeneca's COVID-19 vaccine tie together. 

Vials with the AstraZeneca-Oxford vaccine are pictured at the vaccination centre in Nuremberg, southern Germany, on March 18, 2021. Canada's advisory committee on vaccines recommended against the use of this COVID-19 vaccine for people under age 55. (Christof Stache/AFP/Getty Images)

'What if I've already had one dose?' Your AstraZeneca vaccine questions answered
 

Canadians have been on a roller-coaster with changing guidance on the AstraZeneca-Oxford vaccine, but an infectious disease specialist says there's reason to be optimistic.

Dr. Zain Chagla, an associate professor of medicine at McMaster University and physician at St. Joseph's Healthcare in Hamilton, Ont., said there's still time before those who've had one shot of AstraZeneca vaccine are due to have their second, and that studies being conducted right now will provide clear direction on how to proceed.

Guidance around who should have the AstraZeneca-Oxford vaccine has shifted a few times in recent months as more is learned about its efficacy and side effects.

On Monday, Canada's National Advisory Committee on Immunization updated its recommendations on the vaccine, advising against its use for people under 55 due to concerns about rare blood clotting incidents reported in Europe. (Health Canada said there have been no incidents of blood clotting from among the 300,000 doses of AstraZeneca vaccine administered here.) 

Chagla urged Canadians not to despair over the latest of what may feel like a series of setbacks to Canada's vaccine effort. 

"Yes, there's a little bit of instability now with cases rising," he said. "But there is a hope out of all of this, and Israel and the United Kingdom are really showing us that these vaccines work well in a population. We just need time to get them out there."

Chagla joined Dr. Brian Goldman, host of The Dose and White Coat, Black Art, to answer questions about AstraZeneca submitted by show listeners and to Ask CBC News at COVID@cbc.ca.

Listen to The Dose for free on CBC Listen or on your favourite podcast app — including Apple Podcasts and Google Podcasts.

Thanks for reading! You can email us any time at secondopinion@cbc.ca with your comments, questions, thoughts or ideas.