‘Very little excuse’ to continue to use Astrazeneca in Canada, specialist says
The odd blood clotting disorder linked with Oxford-astrazeneca’s COVID-19 vaccine is a different kind of clotting problem, one that requires more extensive care, can’t be predicted and is “really kinda bad,” says a Toronto infectious diseases specialist. The case fatality rate ranges between 25 and 40 per cent.
For those reasons and more, Dr. Andrew Morris believes it’s time to halt Astrazeneca’s shots in Canada, except for people aged 40 or older living in hotspots with a high amount of disease activity and a high risk of infection, and only then if people face a two- to three-week delay in getting a Pfizer-biontech or Moderna shot — MRNA vaccines that haven’t been associated with the same blood clot “safety signal.”
There is “essentially no scenario” outside of the hardest-hit regions where it is beneficial to give Astrazeneca rather than wait for an alternative, Morris, a member of Ontario’s COVID-19 science advisory table, said in an interview. While stressing that he wasn’t speaking on behalf of the table, “there is very little excuse for us to be continuing to give Astrazeneca to Canadians” because the estimated risk of a clotting disorder is too high, Morris said.
It’s the latest shot to the controversy-plagued vaccine. Alberta is moving to stop using Astrazeneca for first doses, The Globe and Mail reported Tuesday. “Because we have so much MRNA vaccine, these are the vaccines that we are recommending for people to book their first dose with,” unless they can’t take an MRNA vaccine for health reasons or prefer the Astrazeneca shot, Dr. Kirstin Klein, a local medical officer of health for northern Alberta told the Globe.
Provincial medical officers of health across the country are reviewing the use of Astrazeneca. The European Union, meanwhile, has opted not to renew its Astrazeneca contracts, which expire in June. In Norway, an expert panel is urging both Astrazeneca and Johnson & Johnson vaccines be ditched over the blood clot scare.
According to Health Canada, the current estimated rate of VITT in Canada is approximately one case per 100,000 persons vaccinated with the Astrazeneca vaccine.
Ontario’s COVID science table, in a brief published Friday, said the risk, based on published estimates, could be as much as one in 26,000, or as little as one in 127,000.
Morris’ best estimate is that one in 40,000 doses will lead to VITT, and that VITT frequently results in complications, with about one in five leading to death and many more cases of severe illness. Given the risk, Astrazeneca only makes sense for those at high risk of COVID, he said. “But why give them AZ, when we can give them an MRNA vax?”
Twelve cases of VITT — vaccine-induced thrombotic thrombocytopenia — have been reported in Canada, including three deaths. “To me, the most important issue is, we were aware of this a month ago — we probably didn’t appreciate the frequency as much a month ago, although we suspected it,” Morris said.
With two million combined doses of Pfizer and Moderna arriving weekly through May, and 2.4 million combined doses per week scheduled for June, Canada will soon be “swimming in vaccine,” Morris said. “I think that the regulators should say very clearly that, if there are no options for an MRNA vaccine and the incidence of cases is X number, then only in that situation should Astrazeneca be used.”
Some worry this messaging will only make people more confused and concerned. But others agree with Morris. “I’ve done the numbers, too,” University of Toronto epidemiologist David Fisman said on Twitter. “AZ was a useful tool, but our knowledge and understanding, and our supply of other vaccines, has changed. VITT is devastating. We need to move on.”