After safety review, Health Canada says people shouldn't hesitateto get AstraZeneca vaccine

Following reports of rare blood clotting events among some who have received the AstraZenecavaccine, Health Canada officials said today they still believe the product is safe and Canadians should have no qualms about rolling up their sleeves for it when the time comes.

Speaking to reporters at a technical briefing, Dr. Supriya Sharma, Health Canada's chief medical adviser, said there is a "very low risk" that some patients could develop blood clotting with low platelets followingvaccination.

Sharma said that with a third wave of COVID-19 ragingand with the risk ofhospitalization and death still much greaterthan the risk of developing clots followingan AstraZeneca shot the benefits ofthis vaccine clearly outweigh any risks.

"Get whatever vaccine is available to you. It's that simple. The longer you wait to get vaccinated, the longer you're not protected," Sharma said. "We know the risks of getting these side effects from the vaccine are very rare."

WATCH: Health Canada'sDr. Supriya Sharma on theAstraZenecavaccine

Health Canada medical adviser says Canadians should take the first vaccine that's available

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Dr. Supriya Sharma tells reporters the COVID threat is "real" and outweighs rare instances of blood clots reported with the AstraZeneca and Johnson and Johnson/Janssen vaccines.

Pointing to evidence from the U.K., where the AstraZeneca shot has been administered 20 million times, Sharma said the chance of developing these clots is roughly 1 in 250,000.

While there are other numbers circulatingabout the frequency of these clots, Canada is relying on the British data because the U.K. hasa robust safety monitoring system and has administered a lot ofshots, Sharma said.

Meanwhile, Sharma said,the odds of developing a "regular" clot and not this rare, vaccine-inducedthrombocytopenia(VIPIT)in people with low platelets are 1 in 5 for people hospitalized with COVID-19.

The risk of a woman between the ages of 15 and 45 developing any sort of blood clot is 1 in 3,300. If theytake birth control, the odds are1 in 1,600. If a woman is pregnant, the risk is 1 in 300, Sharma said.

"It is difficult to wrap your head around these abstract numbers and relative risks. We understand that," Sharma said. "The risk of regular clots with COVID is much, much higher and it's much, much higher than having this very severe clot."

Health Canada stillhas not definitively associated the AstraZeneca vaccine with these clots. Sharma said only that the shot was "probably" the reason why some people developed this condition.

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We're trying to identify a risk factor that can connect rare blood clots in certain people to a vaccine, says Dr. Ishac Nazy of the McMaster Platelet Immunology Laboratory.

Sharma said the department has updated the product label to warn would-be patients about the risk of developing these clots. Patients who receive the shot will be told to look out for symptomssevere headaches, abdominal pain, leg painor shortness of breath.

Sharma said that ifregulators concludeat any time thatthe risks of theAstraZenecashotoutweighitsbenefits,Health Canada won'thesitate to pull the vaccine'sauthorization.

She said it's not unusual for such very rare side effectsto emerge when a vaccine has been given to suchlarge numbersof people.

One woman in Quebec has developed clots afterreceiving the Covishield product, a biologically identical version of theAstraZenecavaccineproduced by the Serum Institute of India. The woman who isover the age of 55, according toHealth Canada is recovering at home.

Sharma said these rare blood clots can be diagnosed and treated.

Other authorized products widely used in the medical profession canpresent similar rare clotting risks.

Heparin,an anticoagulant (blood thinner)medicationsometimes used in the treatment ofheart attacksandangina, canlead tothrombocytopenia(low platelet count), Sharma said. The possibility of rare side effects doesn't render a product useless, she said.

"Heparin medication, that seems to trigger the same type of reaction. We still have heparinon the market, we still use it for prevention," she said.

In approving the vaccine in late February, Health Canada regulators authorized its usefor all adults 18 and over.

WATCH:Health Canada says people shouldn't hesitate to get AstraZeneca vaccine

Health Canada says people shouldn't hesitate to get AstraZeneca vaccine

3 years ago

Duration 5:43

After its safety review into blood clots, Health Canada's chief medical adviser Dr. Supriya Sharma says people still shouldn't hesitate to get AstraZeneca vaccine, because "you are far more likely to be in the ICU with COVID-19, than you are to have this type of very rare event".

Sharma said Health Canada still believes that the shot can be safely deployed in all adults regardless of age. However, the National Advisory Committee on Immunization (NACI) has recommended that provinces restrict access to adults over the age of 55 for now.

Sharma said NACI is reviewing more real-world data now and could updateits guidelines.

"NACI is looking at it. We've presented ourdata to them. They will provide a recommendation and that may include a change in age they're re-looking at the age," Sharma said.

A recent study from the Cambridge University-based Winton Centre for Risk and Evidence Communication found, after crunching the number of vaccine-related injuries, that the benefits of a AstraZeneca shot easily outweigh the potential risks in virtually every age cohort and among people facing low, medium and high risks ofexposure to COVID-19.

The shothas keptthousandsof people out of hospitaland has pusheddown ICU admissionrates dramatically in the U.K.,the study found.

StatisticianDavid Spiegelhalter, director of the Winton Centre, said the risk of developing a blood clot is "tolerable."

"For most people, when there is virus circulating, the risks of COVID-19 outweigh the minimal risks from the vaccines," Spiegelhalter wrote in his report.

"What else has roughly a one in 100,000 chance for a young adult? We could choose from the risk of dying when under general anaesthesia, or in a skydiving jump, or, on the positive side, winning the Lotto jackpot if you bought 450 tickets, or guessing the last five digits of someone's mobile phone number,"Spiegelhalter wrote.