Infectious diseases specialist Dr. Zain Chagla answers questions about how much protection three doses of a COVID-19 vaccine offer several months out, as well as the status of fourth vaccine doses. #COVID19 #COVID19Vaccine #Canada Watch The National live on YouTube…

Infectious diseases specialist Dr. Zain Chagla answers questions about COVID-19 booster shots and whether they’re necessary at this point in the pandemic. Watch The National live on YouTube Sunday-Friday at 9 p.m. ET Subscribe to The National: Connect with The…