Ontario likely to mix 1st and 2nd vaccine doses amid lack of AstraZeneca supply

Ontario will likely mix and match COVID-19 vaccine doses in light of uncertain future supply of all the shots approved for use in Canada.

Health Minister Christine Elliott says it's likely that recipients of the Oxford-AstraZeneca vaccine may receive a different shot for their second dose.

The province is waiting for the results from a U.K. study on mixing different vaccines and on advice from a federal immunization panel.

Quebec has also said that it plans to mix vaccines due to supply shortages, substituting the Pfizer-BioNTech vaccine for the Moderna vaccines in order to quickly give booster shots to long-term care residents.

It's unclear when more Oxford-AstraZeneca shots will arrive but Ontario is expecting millions of Pfizer-BioNTech shots in the coming weeks.

Biologist and science communicator Samantha Yammine says some Canadians who have already received the Oxford-AstraZeneca shot may be comforted to know they have the option of a different dose.

She says the pandemic has given rise to an "infodemic," with a flood of advice about areas like the low risk of blood clots from viral-vector shots compared with mRNA vaccines.

Even with more mRNA vaccines on the way, Yammine says Canada should be careful about dismissing shots like Oxford-AstraZeneca's because they are important to ending the global pandemic.

The National Advisory Committee on Immunization sparked controversy when it recommended that Canadians who aren't at high risk from COVID-19 may want to wait until a dose of Pfizer-BioNtech or Moderna is available, calling them the "preferred" vaccines.

The comments were met with harsh criticism from public health officials and members of the public, and the chair of the committee said last week that the recommendation was not "retrospective" and that those who got the AstraZeneca vaccine did the right thing to protect themselves and their families.