Vaccine delays could cause issues with immune response: experts

EDMONTON (CityNews) – Canada’s vaccine supply will slow to a trickle for the coming weeks. That’s forced some second doses to be pushed back, but the initial belief that it must be administered in three or four weeks may not be true.

“Both vaccines have data out, 42 days, and within that poll there was no problem seen in terms of the immune response,” explained Infectious Disease Specialist Lynora Saxinger. “I had actually booked my appointment at the outer time of those available.”

The problem is Monday marks 42 days since Canada’s first vaccinations. For some of those who received the first shot – including some long-term care residents in Quebec – the wait continues for round two. One dose still boosts protections 50 per cent for Pfizer and 80 per cent for Moderna, but below the 95 per cent to doses delivers.

“It’s a bit of a question mark, what would happen if people didn’t get the second dose,” explained Thomas Tenkate, Ryerson School of Occupational and Public Health.

“We think that you might have 50 per cent immunity from the first dose but we don’t know how long that will last.”

How are provinces coping? Alberta is pushing appointments back as far as 42 days. But Quebec is pushing second doses up to 90 days to help secure more initial vaccinations.

“It’s not a crazy thing to do, but it shouldn’t be done out of routine. I think that should only be done as part of a study with careful monitoring of whats going on,” said Saxinger.

There is concern that one dose could also do less to mitigate spread, but the data is still unclear.

“We know that people with symptoms actually do spread the disease much more effectively and that asymptomatic can, but don’t spread as much, mostly because they’re not blowing their noses, and touching door knobs and touching their face,” explained Saxinger.

Ultimately, experts say its important to get the second dose, no matter the time frame. The key then becomes for governments and health agencies to not forget the issues learned during this initial vaccine rollout.

“You need the two doses in essence to train your body to respond to the vaccine, whereas the older type of vaccines just generally require one dose,” explained Tenkate.

“We might learn that for a short period of time, and we put in those systems and structure. But then five years later, nothing has happened, do we really need all of those resources?”