TORONTO — Ontario’s top doctor says the province will now allow second doses of Oxford-AstraZeneca COVID-19 vaccine to be administered.
Dr. David Williams, Ontario’s chief medical officer of health, said the second dose administration will begin with those who received their first dose between March 10 and 19.
“Nothing is more important than the health of Ontarians, and for the best protection against COVID-19 it is vital that everyone who received the AstraZeneca vaccine for their first dose receives a second dose of a COVID-19 vaccine,” said Williams.
Shots will begin to the week of May 24, with informed consent. Williams said those who are eligible should contact the provider who administered their first dose to book their appointment.
The announcement immediately applies to those who received their first dose during Ontario’s initial pharmacy rollout at locations in Toronto, Windsor and Kingston.
Williams was joined at Friday’s update by Dr. Dirk Huyer, the co-ordinator of the provincial outbreak response.
For those who received their first dose after March 19, they will be able to get their second shot within the recommended interval of 12 weeks. Williams said more info will be made available soon.
“The province is working with primary care providers and pharmacies to ensure second dose appointments are scheduled in advance of the 12-week interval,” Williams said.
Several provinces have stopped giving the shot because of concerns about rare, fatal blood clots. However, Williams said the health risks posed by the vaccine are low.
He said new data indicated the benefits far outweigh the risk with second doses.
“Data from the UK strongly suggests a much-reduced risk of VITT in second doses of AstraZeneca — one in 600,000,” a release said Friday.
Ontario had paused the use of the vaccine but still had tens of thousands of doses in storage. Huyer said there are 55,000 doses set to expire by May 31.
Nearly one million Ontario residents got the AstraZeneca vaccine as their first shot between March 10 and May 11.
Health authorities were trying to decide whether to resume using the AstraZeneca shot or if a different vaccine should be substituted for second doses.
Ontario said it is still waiting on a recommendation on mixing doses from the National Advisory Committee on Immunization (NACI).
More than 7.5 million doses of a COVID-19 vaccine have been administered in Ontario, with formulations from Pfizer-BioNTech, Moderna, and AstraZeneca.
—With files from The Canadian Press