Vaccine panel says Canada can delay 2nd dose of COVID-19 vaccine

Canada's national panel of vaccine experts says the second COVID-19 vaccine dose can be delayed briefly in order to quickly get first doses to more people.

The National Advisory Committee on Immunization says every effort should be made to follow the 21-day and 28-day dosing schedules recommended for the two vaccines approved in Canada to date.

But as the pandemic heats up, and as vaccine supplies trickle in slowly, the panel also says that delaying the second dose for up to six weeks — instead of three or four — could quickly give more people at least some protection against COVID-19.

Dr. Gaston De Serres is an epidemiologist practitioner with Quebec's National Public Health Institute and sits on the scientific immunization group that recommended the one-dose model to the province's government.

"It will reduce much more the burden in terms of hospitalizations and death by giving one dose to as many people as possible, rather than having half as many people vaccinated with two doses," De Serres said today.

Canada is getting enough vaccine doses to vaccinate the vast majority of Canadians by the fall — but most of those doses won't arrive until later in the spring and summer, and provinces are warning they're going to run out.

Almost 550,000 doses have now arrived in Canada and about 71 per cent of them have been injected. Another 380,000 doses are scheduled to arrive by the end of the week.

Clinical trials for the Pfizer-BioNTech and Moderna vaccines showed the first dose provided some protection against serious illness from COVID-19. But the majority of patients in both trials received a second dose on schedule, leaving very limited data on how long the protection from the first dose lasts.

Alan Bernstein of Canada's COVID-19 vaccine task force said he is opposed to delaying the second dose. 

"It would create a situation where people think they're immune, but they're not," he said. "If we start tampering with those regimes, we really are experimenting on human subjects, and we need to get informed consent."

If provinces change shot schedules, it might also affect the delivery of future doses. Procurement Minister Anita Anand said Tuesday she'll consult with the companies. 

"In our negotiations with the vaccine manufacturers they, of course, are concerned when the recommended doses, based on their clinical trials, are not being followed," Anand said.

Governments are not required to follow the public health recommendations from the National Advisory Committee on Immunization.