Ontario begins giving second doses of AstraZeneca vaccine Monday

Ontario began administering the second dose of the AstraZeneca COVID-19 vaccine Monday.

Anyone who received their first AstraZaneca shot between March 10 and 19 is now eligible for a second one.

The second doses for this group come two weeks earlier than recommended — around the 10 week mark rather than 12 weeks, which is considered the optimal interval to ensure the best immune response.

The dose schedule was moved up in an effort to make use of the 55,000 AstraZeneca shots in stock that are set to expire on May 31.

Infectious disease specialist Dr. Isaac Bogoch explains that administering the shot slightly earlier will make very little difference to the efficacy of the shot.

“Let’s just out it this way — it would be very unlikely for someone who has been fully vaccinated [with two doses], regardless if it’s been at 10 weeks or 12 weeks to land themselves in hospital,” he said.

Ontario also has 250,000 more AstraZeneca doses to continue administering second shots in June and another shipment may arrive in late June as well.