Canada could be mixing and matching COVID-19 vaccines by the summer: Tam
TORONTO -- Canada’s top doctor believes Canada could be mixing different kinds of COVID-19 vaccines in the next few months, as several provinces have already halted administering first doses of the AstraZeneca vaccine over concerns surrounding rare blood clotting.
In an interview during CTV News Channel’s “Get the Facts on the Vax” special on Wednesday, Canada’s chief public health officer Dr. Theresa Tam was asked whether Canadians who already received a dose of AstraZeneca would be given a second dose of another brand this summer.”
“That's a possibility,” she said. “It will be really helpful, because then it makes subsequent doses easier to administer and predict, given the supply.”
Tam’s comments come as preliminary results from the United Kingdom-based study showed that receiving one dose of Pfizer's COVID-19 vaccine and one dose of AstraZeneca's vaccine is safe, but could result in more frequent mild side-effects.
The early results, published in a research letter in the journal The Lancet on Wednesday, looked at 800 individuals who were given Pfizer and AstraZeneca vaccines and found that there were more frequent minor side-effects – including fever and fatigue – compared to those who received two doses of the same vaccine.
The research did not measure how effective mixing doses is in fighting COVID-19, however.
“Early indications are looking favourable towards use of an mRNA vaccine if you had a first AstraZeneca vaccine,” Tam said. “We'll be providing advice, hopefully hearing from the National Advisory Committee on Immunization shortly.”
This week, several provinces, including Ontario, Alberta, Manitoba, Saskatchewan and Nova Scotia, halted or restricted inoculation with the AstraZeneca vaccine due to a lack of supply and out of an abundance of caution concerning rare cases of blood clotting known as vaccine-induced immune thrombotic thrombocytopenia (VITT).
VITT is estimated to occur in one in every 100,000 to one in every 250,000 people vaccinated with the AstraZeneca vaccine.
Despite the concerns, Tam said the AstraZeneca vaccine is safe and anyone who took it already did the right thing.
“If you’re looking at those effects, overall vaccines are safe and effective and Health Canada has essentially authorized their use, but with millions of vaccines going into arms across the world, you're beginning to see some rare effects,” she said.
Dr. Marla Shapiro, CTV News' health and medical expert, said she wasn’t surprised to hear Tam suggest that Canada could soon be mixing vaccine brands.
“I think that there's a possibility that it will happen, and I think we're expecting to see that the data is going to look good, but given the communication and how lightly we're treading in that, we don't want to take a road without having the science to tell us about the efficacy,” she said.
“It's just speculation at this point.”
With files from CTVNews.ca Writer Alexandra Mae Jones