Chatham’s top doctor remains confident the more than 2,000 Chatham-Kent residents who got a dose of AstraZeneca vaccine made the right call.
“Some reassurance to people that have received it already: getting the serious side effect of VITT is about four times less likely than getting struck by lightning,” says Medical Officer of Health Dr. David Colby.
VITT, known long-form as vaccine-induced thrombotic thrombocytopenia, entered the vocabulary of many Canadians last week when the Ontario government announced a pause on administering first doses of the AstraZeneca vaccine. The condition results in serious blood clotting which can be fatal if not treated.
But cases of the vaccine side effect are rare. Ontario says the incidence rate is 1/60,000. Colby says there have been no reports of VITT in Chatham-Kent in the 2,400 people who received an AstraZeneca dose.
“England is doing very well in terms of its pandemic control and they predominately used the AstraZeneca vaccine in order to get there,” says Colby.
“The primary factor in putting that pause is that our supplies of mRNA vaccines (Pfizer and Moderna), which are not associated with this rare side effect, are increasing and stabilizing across Ontario,” he says.
Second doses of AstraZeneca are still recommended if no VITT was experienced after the first. The chances of the blood clots drop to 1/1,000,000 with the second dose. They will continue to be administered by pharmacies and health teams so people will be able to get their second dose after the recommended 12 week interval.
The second dose situation continues to evolve though as studies are conducted to see if mixing vaccines provides as strong a result of immunity. Colby is optimistic but won’t commit until the data is in.
“As soon as there is evidence that you can use the first dose with one vaccine and the second dose with another I will heartily endorse that,” he says. “I don’t have any inherent bias toward that in general. I just want to see some evidence that it works well before we start recommending it.”
Alex Kurial, Local Journalism Initiative Reporter, The Independent