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Health Canada concludes AstraZeneca benefits outweigh blood clot risks

Last Updated Apr 14, 2021 at 12:57 pm CDT

Health Canada says a new and extremely rare blood clotting syndrome may be linked to the AstraZeneca vaccine, but the agency says the benefits of the shot still far outweigh any risks.

The agency says there is no evidence showing certain people are more at risk than others and the vaccine will remain authorized for all adults in Canada.

Dr. Supriya Sharma says Health Canada will be updating the label for the vaccine to warn of the possibility of blood clots.

The conclusions come after the department’s drug regulatory experts completed a review of safety data.

Sharma stresses the risks from the vaccine are very rare and she is urging Canadians to get whichever shot is offered to them.

“The longer you wait to get vaccinated, the longer you’re not protected,” she says.

Health Canada says the risk of getting the blood clot is four in one million.

The clotting syndrome, now known as VIPIT, occurs when the body’s immune system begins to attack blood platelets, leading to clots.

Health Canada says scientists have figured out what is happening but they haven’t been able to explain how the vaccine is causing it.

Sharma says the National Advisory Committee on Immunization (NACI) will be meeting to review the new safety data and will decide whether or not to update its guidance to provinces.

NACI recommended a pause on AstraZeneca vaccinations for people under 55 last month. The advisory committee’s concerns stemmed from a possible link between the shot and the rare blood clots.

The panel said that adults 55 years of age and older may still be offered the shot with informed consent.

The drugmaker updated the efficacy data for its vaccine last month and say the shot is 76 per cent effective against mild symptoms and 100 per cent effective at preventing severe disease from the virus. In trial volunteers aged 65 and older, the vaccine was 85 per cent effective in preventing symptoms.

Canadian health officials first recommended the AstraZeneca vaccine for those under 65, but on March 16 it adjusted its advice to say that it could also be given to seniors.

Canada reported its first case of vaccine-induced blood clots linked to AstraZeneca on Tuesday, and the United States put the brakes on the Johnson & Johnson vaccine following six reports of blood clots there.

However, officials in both countries continue to stress the vaccines are safe, and their benefits outweigh their risks, even as investigations into what is causing the clots continue.


First report of blood clot linked to AstraZeneca in Canada

A Quebec woman is the first in Canada to develop a blood clot after being vaccinated with the Oxford-AstraZeneca vaccine.

The Quebec health ministry and Public Health Agency of Canada reported the event connected to the AstraZeneca vaccine Tuesday.

The female patient, whose age has not been revealed, received the appropriate care and is recovering at home.

More than 700,000 doses of the vaccine have been administered in Canada and about two million doses have been shipped.

The rollout of the Oxford-AstraZaneca vaccine in Canada has been shrouded with confusion, due to safety concerns and changing guidance over who can receive the shot.

Health Canada asked AstraZeneca for a full risk assessment of its vaccine after reports of similar clots in Europe, but the agency says the side effect is extremely rare and the vaccine’s benefits still outweigh its risks.

Experts say the risk of getting blood clots from COVID-19 itself is far higher than from the vaccine.


U.S. recommends pause of Johnson & Johnson

The U.S. recommended a “pause” in administration of the single-dose Johnson & Johnson COVID-19 vaccine on Tuesday to investigate reports of potentially dangerous blood clots.

Health Canada is investigating the matter and is contacting the U.S. Food and Drug Administration (FDA) and the drugmaker to get more information.

The single-dose vaccine has already been approved for use by Health Canada though it has yet to be delivered and distributed. Doses were expected to start arriving in the last week of April, there has been no word on who would be prioritized for the single-dose vaccine.

Canada has pre-ordered 10 million doses of the shot with an option to order 20 million more.

For the moment, the Prime Minister says Canada is still due to receive its first shipment at the end of the month

In a joint statement Tuesday, the Centers for Disease Control and Prevention (CDC) and the FDA said they were investigating the reports of reduced platelet counts and blood clots that occurred in six women in the two weeks following vaccination.

Among the six cases, one woman died and another is in critical condition.

CDC’s Advisory Committee on Immunization Practices says they will meet Wednesday to further discuss the rare cases.

“Until that process is complete, we are recommending a pause in the use of this vaccine out of an abundance of caution,” Dr. Anne Schuchat, Principal Deputy Director of the CDC and Dr. Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research said in a joint statement.

Federal distributors of the shot will cease administering it and other providers, including states, are expected to follow suit.

Dr. Paul Offit is a member of the FDA vaccine advisory committee and says the clots didn’t come up in trials because it is such a rare event.

“If you look at the way that J&J did their trial, it was roughly a 44,000 person trial, if an event is occurring in one and a million people you are unlikely to see that,” says Offit. “It should be reassuring to people that we are always looking to make sure that there isn’t even a very, very rare side effect.”

More than 6.8 million doses of the Johnson & Johnson vaccine have been administered in the U.S to date.

With files from the Canadian and Associated Press