This isn't the first time the top doctor has mentioned mixing and matching vaccines.
People in Canada who got the AstraZeneca vaccine for their first dose will "likely" be able to have a choice for their second dose, according to Dr. Theresa Tam.
The country's top doctor said on May 18 that the National Advisory Committee on Immunization (NACI) is looking at data from a Spanish study about administering the Pfizer vaccine as a second dose when AstraZeneca was used as a first dose.
"It is likely that people in Canada who've received one dose of AstraZeneca will have a choice for their second dose," Tam said. "I think everybody's anxious to make sure people who got the first dose of AstraZeneca does have the ability to get that second dose."
A week before her announcement, both Tam and Justin Trudeau confirmed that Canada is looking at using different vaccines for first and second doses after preliminary data from a U.K. study about mixing and matching vaccines was released.
Tam said the NACI will be providing a recommendation about this to the provinces and territories, but she didn't provide a timeline of when that could happen.