Ultra-cold storage and slowing transmission: Your COVID-19 vaccine questions answered
Physician and infectious disease expert Dr. Barry Pakes answers listener questions about coronavirus vaccines
Amid reports that the federal government's top health agency could soon approve a COVID-19 vaccine, the start of a return to normalcy may feel within reach for many Canadians, a Toronto physician says.
While pandemic-related restrictions will likely remain in place for many more months, there is reason for optimism, said Dr. Barry Pakes, a physician and assistant professor at the University of Toronto's Dalla Lana School of Public Health.
"I do think we're going to get a lot closer to the new normal, or a reasonable normal for many of us, within the next three to six months," he told Cross Country Checkup host Ian Hanomansing.
Prime Minister Justin Trudeau announced Monday that Canada would receive 249,000 doses of Pfizer/BioNTech's two-dose COVID-19 vaccine candidate by the end of December. The first doses should arrive next week, pending regulatory approval, he said.
The announcement comes one day after BioNTech chief business and chief commercial officer Sean Marett told CBC News that the first deliveries for their product could be shipped to Canada within 24 hours of government approval.
Health Canada is expected to approve Pfizer/BioNTech's mRNA-based COVID-19 vaccine in the coming days.
Still, many Canadians have questions about the vaccine's rollout and safety.
As part of Checkup's regular Ask Me Anything series, Pakes took calls and answered listeners' questions about COVID-19 vaccine candidates.
Will a COVID-19 vaccine stop virus transmission?
Calling from Lindsay, Ont., Jennifer Parsons asked if the vaccines currently being tested will prevent immunized people who are exposed to COVID-19 from spreading the illness.
Pakes explained that the vaccine candidates are designed to develop an immune response to the spike proteins of the coronavirus.
"What that does is help the body fight off the virus once it's already in your system and it prevents the virus from multiplying as much," he said.
That immune response will in turn help prevent illness — and, hopefully, serious illness and death. And because it slows the virus' ability to multiply in the body, someone carrying the virus will be less likely to spread it, Pakes added.
But a vaccine will not "kill" the virus if it enters your body, he said.
"It's not as if you inhale it, and because you've taken that vaccine, it's dead on contact."
Can COVID-19 vaccines spread infection?
Bonnie McBride in Montreal questioned whether a COVID-19 vaccine would cause immunized people to be infectious.
"It's a good question because some vaccines that we do have are live vaccines, like for varicella or chickenpox, for example ... but even those are not the actual infectious vaccine themselves," Pakes said.
"So while they can in theory be spread, that doesn't really happen in practice."
Why do some COVID-19 vaccines need to be kept cold?
Certain vaccines, including the much-discussed Pfizer and Moderna products, must be stored at ultra-cold temperatures and Andre Laberge in Meritville, Ont., wanted to understand why.
"Is it susceptible to spoil very quickly once it's removed from the freezer?" he asked Pakes.
The Pfizer and Moderna vaccines are both based on mRNA technology, which Pakes says is a "very fickle molecule."
"So it is something that will denature … very easily once it's at room temperature, or even at the temperature we normally keep vaccines at, which is two to eight degrees," he explained.
The risk of ruining the vaccine doses is what makes transporting the vaccines so tricky.
"Given how valuable these are for all Canadians as individuals and all of our population in order to start opening up again, that's why [the] logistics [are] so complex and why we're taking such great care to make sure that everything is really in place," he said.
What additional information should we expect?
Pakes says that while Health Canada will have access to detailed data and reports from Phase 3 clinical trials, infectious disease doctors like himself are largely working from publicly-available information.
"All we've got is really what we're seeing in the media," he said. "We're not seeing a lot more than that."
While Phase 3 trial data suggests the vaccines are safe, the true level of protection the vaccine provides will not be obvious until the vaccine is rolled out on a larger scale and additional data is gathered.
"What that's called is a Phase 4 trial, which is really just when it gets out in the population [and] we keep good track of who's got the vaccine, of illnesses in those people and in the community, and [watch] how the disease dynamic changes," he said.
While much is still unknown, he says the available data looks positive.
"Even if in practice the protection is half of what it's reported to be, I think we're still in a situation where these are game-changing vaccines."
Written by Jason Vermes. Produced by Steve Howard.
