OTTAWA -- While Canada’s top immunization experts have signed off on provinces delaying the administration of the second Pfizer and Moderna doses in an effort to begin vaccinating more people with a small supply, Procurement Minister Anita Anand says she’s heard concerns from the manufacturers that may impact future deliveries.

In an interview on CTV’s Question Period airing on Sunday, Anand said that some drug companies have brought up concerns with Canada or other countries not following the recommended usage protocols set out by the vaccine manufactures, as they are based on data from their clinical trials.

“That has not directly impacted our deliveries to date, but it has been a concern that vaccine corporations have raised with us in our discussions,” Anand said. While she would not say whether a company has outright said it would withhold future doses, she said the issue has come up in negotiations.

“It is still a recommendation from the manufacturers that we are hearing at the table” to follow their protocols, she said.

This week, the National Advisory Committee on Immunization (NACI) approved delaying administering second doses of the Pfizer and Moderna vaccines for up to 42 days. The decision was made in the face of rising cases and strained hospitals.

The two vaccines that have been approved in Canada so far – made by PfizerBioNTech and Moderna -- require two separate doses in order to achieve 94-95 per cent immunity for the patient.

These doses are spaced apart. Pfizer’s second dose is intended to be delivered 21 days after the first, while Moderna’s has a 28-day wait in between the doses.

The report from NACI stated that while the ideal is to follow the vaccine manufacturers' recommendations, people can wait longer -- 42 days or so for the second dose -- in order to allow double the number of Canadians to get some partial protection by receiving their first shot faster.

However, contrary to NACI’s recommendations, Quebec public health officials have announced they plan to prolong second doses in that province for up to 90 days between the first and second dose, and Ontario indicated on Friday that given the upcoming temporary Pfizer shortage that province may also extend the timeframe between doses. 

SOME TRIAL PARTICIPANTS HAD DOSE DELAYS

In a separate interview on CTV’s Question Period, NACI chair Dr. Caroline Quach-Thanh said that while Pfizer and Moderna have recommended shorter windows between vaccinations, in phase three trials for both vaccines, candidates received their second dose up to 42 days after the first.

“So the actual vaccine efficacy that are reported in those trials are covering a span from 21 to 42 days. It's impossible to say if people who got their second dose at 42 days are protected better, less, or worse than the ones that got it before,” she said.

She’s suggesting Quebec conduct surveillance to ensure the vaccine remains effective if the second shot is given so late after the first.

“If we had enough doses to vaccinate all the high-risk groups right away with it two doses, we would stick to label. But at one point in time if you have to choose between vaccinating only a small proportion of your population, and let the variant spread very quickly, there’s no health gains here,” she said.

With files from CTV News’ Alexandra Mae Jones, CTV Montreal and CTV Toronto.