4-month gap between COVID-19 vaccine shots could be reduced, some AZ doses may go to waste

Ontario health officials say they are hopeful the current four-month interval between COVID-19 vaccine doses will be reduced as vaccine supply increases and more people get their first shots.

Provincial medical officer of health Dr. David Williams said the decision to increase the interval of the vaccines from the manufacturer recommended three or four weeks to four months was made to ensure “maximum benefit in the shortest time, with everybody getting one dose.”

That goal has been largely achieved with almost 60 per cent of the province’s population vaccinated with the first dose, he said.

“As we go forward … and we get lots of vaccine supply, we’re not going to leave it in fridges,” said Dr. Williams. “If we feel that we can go on to second doses with people, we certainly will — we won’t wait for the four months. We would like to do it sooner if we can.”

Dr. Williams added that along with supply, the decision will be influenced by how quickly all age groups are vaccinated with their first dose. The province expanded vaccine eligibility to all those 18 and over, starting Tuesday.

He also said that future second dose appointments that have already been booked are not set in stone. The province’s Covax booking system is flexible and appointments can be adjusted as per supply.

Ontario’s associate medical officer of health Dr. Barbara Yaffe added that she does not foresee the gap becoming “really short,” especially for the AstraZeneca vaccine.

“We want to make sure that people have enough of an immune response to the first shot,” she said. “With AstraZeneca usually, if you wait a little longer you get a better response to a booster, but we may not need to wait the full four months.”

Concerns have also been raised regarding the wastage of AstraZeneca doses being held in stock that are set to expire soon.

On the 300+ thousand doses of the AstraZeneca vaccine destined for Ontarian’s, sitting on ice at the moment, Ont’s Minister of Health says most second doses aren’t scheduled until late June. Saying “we have time” to make a decision. Some doses expire at the end of May. https://t.co/DQwEKLGNOK

— Adrian Ghobrial (@CityAdrian) May 17, 2021

Dr. Williams said that while a 12-week gap between shots is best for the AstraZeneca vaccine, he is also not willing to wait and give expired vaccines “at all under any means to anyone in Ontario.”

“That would be totally wrong,” he said. “If we can’t use it all, that is what we have to face.”

However, he added that the government is going to try and see if those vaccines can still be utilized before expiration “in a safe way, efficaciously … and with the proper protocols in place.”

He said that currently, not many people have reached the 12-week mark after the first shot and said that getting a second dose too soon will mean less than maximum benefits.

“But some may say ‘that’s fine with me’ … so we’re looking at how we might do that,” he said.

Another factor playing into the issue is where the vaccine is located. Dr. Williams said it is best not to move it around too much in order to avoid compromising the “cold chain” — the protocols in place to keep the vaccine at a sufficiently low temperature.

“It’s not just a matter of [having it], it’s a matter of where is it located and can we utilize it in a way, first that is effective, second it’s safe — the quality is maintained — and that the people receiving it fully understand if they’re getting it before 12 weeks — what does that mean? and how important is that to that person.”

He concluded that informed consent is vital and that safety and quality are the “top priority.”

“We’ll try to do what we can and utilize [the doses in stock], but expiration dates are expiration dates and you have to hold to that rule and you can’t utilize it past that date,” he said.