Article content Itâs 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 âinfodemic,â 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-AstraZenecaâs because they are important to ending the global pandemic.