Picture: REUTERS/DADO RUVIC
Picture: REUTERS/DADO RUVIC

If you asked Canadians if they wanted the AstraZeneca vaccine, a lot would say no. And it wouldn’t be because they were vaccine hesitant. It would be because AstraZeneca, the pharmaceutical company producing the low-cost vaccine developed by Oxford University, has repeatedly mishandled the delicate process of proving the safety and efficacy of shots destined to be put into a billion arms. 

The latest setback came last week when Canada’s national advisory committee on immunisation unexpectedly recommended that AstraZeneca not be given to people under 55 until there is more information about its possible link to a tiny handful of potentially fatal blood clot cases in Europe that seem to strike younger people. Barely 10 days earlier Health Canada had said it was aware of the blood clot issue, but that the benefits of the AstraZeneca vaccine outweighed any risks and that it should be given to people 18 and up.

On the surface it was a confusing reversal. And it came after earlier worries that the vaccine wasn’t proven safe for people over 65 because AstraZeneca’s phase 3 trials included only a small percentage of older test subjects.

AstraZeneca’s research came into question again on March 22, when it said a preliminary analysis of two doses on 32,449 adults in the US, Peru and Chile showed it had a 79% effectiveness rate. That was immediately challenged by the US National Institute of Allergy and Infectious Diseases, which accused AstraZeneca of using data from February to reach its conclusion, and that more recent numbers indicated an efficacy of between 69% and 74%.

It wasn’t a huge discrepancy. AstraZeneca subsequently incorporated the newer data and said its final result showed a 76% efficacy. But the damage to the company’s reputation was done. 

Is AstraZeneca safe or not? And what of Canadians who’ve already received it? Are they at risk of a scary side effect known as vaccine-induced prothrombotic immune thrombocytopenia? 

The answer is that AstraZeneca is safe. Other countries besides Canada have paused its use for younger adults while the blood clots are investigated, but the threat remains minuscule. The fact that the national advisory committee on immunisation is erring on the side of precaution should be reassuring to anyone who has received the vaccine, or is offered it. /Toronto, March 31

Globe & Mail

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