The latest recommendation from the National Advisory Committee on Immunization (NACI) on mixing and matching COVID-19 vaccines has offered some flexibility to Canada’s rollout — but it might come at a cost.
In non-binding guidance released Tuesday, NACI said that the mRNA vaccines from Pfizer-BioNTech and Moderna can be given as a second dose after a person has received a first shot of AstraZeneca. The two mRNA vaccines are also interchangeable if the same product is not readily available for the second dose.
This comes after data from studies in Europe suggest that mixing doses of COVID-19 vaccines is safe and effective.
So far, Saskatchewan and New Brunswick have decided to implement NACI’s guidance to its rollout plan. British Columbia is expected to make an announcement on Thursday. Just prior to NACI’s updated recommendations, Manitoba said it would allow those who got a first dose of AstraZeneca to get an mRNA shot for their second.
As more provinces follow suit, Canada might need to adjust its upcoming vaccine orders from AstraZeneca to avoid any wastage, public health officials and experts say.
“We don’t want to, of course, leave any vaccine doses unused and that has to be minimized,” said Theresa Tam, Canada’s chief public health officer, during a news conference Tuesday.
“We don’t want to be ordering vaccines if we’re not using it,” she added.
Canada has purchased 20 million doses of the AstraZeneca vaccine — enough to vaccinate 10 million Canadians.
As of May 22, more than 2.1 million Canadians had received at least one dose of AstraZeneca and some 6,884 people were fully vaccinated with the two-dose series.
“I am worried about wasting AstraZeneca vaccine doses we have on hand,” said Gerald Evans, chair of the Division of Infectious Diseases at Queen’s University in Kingston, Ont.
“It may now be more challenging to get the second dose of AstraZeneca vaccine into people who remain overly concerned about side effects, despite the fact that VITT, which is quite uncommon, is even less common amongst second dose recipients.”
NACI’s latest advice is driven by the risks of a rare blood-clotting syndrome, known as vaccine-induced thrombotic thrombocytopenia, or VITT linked to the AstraZeneca vaccine.
As of May 12, 2021, the Public Health Agency of Canada (PHAC) had estimated the rate of VITT in Canada to be 1 in 83,000 doses administered. However, as investigations continue, the rate could be as high as 1 in 55,000, PHAC says.
Kerry Bowman, a professor of bioethics and global health at the University of Toronto, said it would be “very ethically problematic” if any of Canada’s vaccine supplies go to waste.
“When you take a look at the global picture, things are not that great and any wastage here would be very ethically problematic from a global perspective.
“And it would also be terrible from an epidemiological point of view in a global context.”
Given that Canada has ordered enough vaccines to cover its entire population twice, an adjustment in its shipments would help divert much-needed vaccines to other countries that lack supplies, said Tania Watts, a professor of immunology at the University of Toronto.
But some AstraZeneca doses can be kept in reserve for the small amount of the population who might have an allergic reaction to the ingredients of the mRNA vaccines, Watts told Global News.
Last week, Health Canada extended the expiry data of nearly 50,000 doses of AstraZeneca vaccine by an extra month to July 1 from May 31.
Several public health experts say they’re confident that Canada’s current batches of AstraZeneca COVID-19 vaccines would still be safe and effective, despite having their expiry date extended by a month.
Meanwhile, NACI has come under fire for sending mixed messages to Canadians by its preferential recommendation of the mRNA vaccines over AstraZeneca and Johnson & Johnson shots.