Boosters will get quick approval, says Health Canada chief medical adviser

Canada's chief medical adviser says her department is constantly receiving and reviewing any data on vaccines and COVID-19 variants and will be ready to quickly authorize needed boosters when they're available.

But Dr. Supriya Sharma said the three vaccines authorized in Canada so far offer excellent protection and, along with public health measures, can help slow the spread of the virus and potentially help stop it from mutating even further.

"We knew this was going to happen, that we would have variants," she said, in an interview with The Canadian Press.

Coronaviruses don't mutate as quickly as the flu, but do change as they spread among people and the more they spread, the more they change. To that end, Sharma said the slower the spread, the fewer variants we will see.

"So a virus is not going to mutate as much when it can't replicate," she said.

There are three variants of concern now identified in Canada, including B.1.1.7, first identified in the United Kingdom, B. 1.351, identified in South Africa, and P. 1, identified in Brazil.

Canada's authorized vaccines, Pfizer-BioNTech, Moderna and Oxford-AstraZeneca, all appear to have very good results against B.1.1.7, which is the most common variant so far found in Canada.

Chief Public Health Officer Dr. Theresa Tam said Wednesday 1,324 cases of B.1.1.7, 103 B. 1.351 and 3 of P. 1 have been identified across Canada.

In Israel, where more than half the population has received at least one dose of the Pfizer-BioNTech vaccine, studies have shown significant reductions in the spread of the virus, as well as hospitalizations and deaths. The B.1.1.7 variant is dominant in Israel, making up more than 80 per cent of the cases there now.

The B. 1.351 variant is a bit more concerning for vaccines. South Africa stopped using AstraZeneca altogether after lab tests suggested it wouldn't be very effective against mild illness for B. 1.351, which is dominant in that country.

That decision has contributed to growing concerns that AstraZeneca's vaccine is less desirable but Sharma said the details aren't that simple.

"Now, if you look at severe disease, or more severe cases, it actually looked like it was still quite protective," she said.

"But in a country where that is your dominant circulating stream, and in a country where they had potentially had access to another vaccine shortly, they made the decision that maybe they weren't going to go ahead with that," she said.

If B. 1.351 becomes a dominant strain here, and the vaccines don't show effectiveness against it, they'll be pulled, she said.

"We wouldn't leave a vaccine on the market, if we think that it wouldn't be effective for the overall population," she said.

All three vaccine makers have to keep updating Health Canada with any information they have about how their injections are handling new variants.

Most are also already working on boosters to address limitations their original vaccines may have.

When those boosters are ready, Health Canada won't need very long to review them, said Sharma.

"We're working with our international regulatory partners, to come together with aligned guidance, to provide to companies to give them some guidance on what type of evidence we would need to see for an updated vaccine," she said.

Health Canada worked with both the U.S. Food and Drug Administration and the European Medicines Agency to establish similar guidelines for what companies had to do to get their COVID-19 vaccines approved the first time.

Canada's authorizations were independent but were completed alongside the U.S. and Europe.

Any boosters would be handled in a similar way to how Health Canada manages the flu vaccine each year, which is adjusted annually to account for the changes in flu strains that are dominant.

Smaller-scale clinical trials and lab tests, that can be completed and reviewed much more quickly, are likely.

"They still need to demonstrate that the vaccine that comes out is still safe, effective and high quality," she said.

This report by The Canadian Press was first published March 4, 2021.