Canada's chief public health officer and deputy chief public health officer Dr. Theresa Tam and Dr. Howard Njoo both said Tuesday that despite recommendations allowing for those who received a first dose of the AstraZeneca COVID-19 vaccine to get a Pfizer or Moderna shot for their second, it is still advised to get the same type of vaccine as their first and the goal overall is not to waste doses. She said they would monitor the uptake of AstraZeneca following the announcement about mixing doses and make a determination from there on what to do with the surplus.