Health-care workers wait in line at a UHN COVID-19 vaccine clinic in Toronto on Thursday, January 7, 2021. THE CANADIAN PRESS/Nathan Denette

Health-care workers wait in line at a UHN COVID-19 vaccine clinic in Toronto on Thursday, January 7, 2021. THE CANADIAN PRESS/Nathan Denette

Canadians who have had COVID-19 should still get the vaccine, experts say

Pfizer-BioNTech and Moderna vaccines were found to have a 95 per cent efficacy

Studies have suggested previous COVID-19 infections may result in promising levels of immunity to the virus, leading to questions of whether those who’ve already recovered from the disease still need a vaccine.

And is there urgency to inoculate them, or can they move to the back of the vaccination line?

Experts say a vaccine will likely offer the safest bet for longer-term protection, meaning those with previous infections should still get them. And prior COVID illness shouldn’t determine someone’s place in the queue.

The exact level of immunity acquired from a natural infection is yet to be fully determined, says Dr. Andre Veillette, a professor of medicine at McGill who’s also on Canada’s COVID-19 vaccine task force.

It may be that protection begins to wane quicker in some people, or that those with previous mild infections aren’t as protected as someone who had more severe symptoms, he says. Still others may think they’ve had a COVID-19 infection but can’t be sure if they didn’t get tested at the time.

“I would say the simple rule would be that we vaccinate people who’ve had prior infections, just like everybody else,” Veillette said. “If you had the infection, yes, you may have some protection, but it may not last a long time, and it may not be as good as the vaccine.”

Pfizer-BioNTech and Moderna vaccines were found to have a 95 per cent efficacy in clinical trials in protecting against severe disease.

But there are still questions around whether the vaccines can actually prevent someone from catching the virus and spreading it to others. While Moderna has some data that their product may protect against acquiring the virus, it’s still unclear.

Antibodies from natural infections suggest the same — that they may protect us from getting really sick again, but not from getting the virus a second time.

While there have been some cases of reinfection around the world, immunology expert Steven Kerfoot says the fact we’re not seeing more of those suggests the immune response from initial COVID-19 infections is probably “pretty strong.”

Kerfoot, an associate professor at Western University, says vaccines are designed in a way that should produce an immune response “at least as good or better” than what we get after a natural infection.

“So it may help fill in holes where people may not have developed an immune response effectively to the virus,” Kerfoot said. “If anything, the vaccine could as act as its own booster that would improve your immunity.”

READ MORE: B.C. adjusts COVID-19 vaccine rollout for delivery slowdown

While some studies have suggested antibodies may disappear relatively quickly after COVID-19 infections, others have found a more lingering immune response. An American study published this month showed antibodies present for at least eight months, and possibly longer.

Even studies suggesting an early drop-off of antibody levels aren’t concerning, Kerfoot says. Infections trigger the body to produce other immune cells and memory cells that reduce slowly over years and help fight off future invasions from the same virus.

If the immune response in those with past COVID infection is expected to be lengthy, could there be justification to defer their inoculations, especially if vaccine supply is low?

It will be up to provinces to decide priority in each stage of their rollouts, but Jason Kindrachuk, a virologist with the University of Manitoba, says that will be a tricky decision.

“I don’t think we can use prior infection as an indicator of priority, because we just don’t know what that person’s immune response actually is,” Kindrachuk said. “We don’t know what long-term immunity looks like in those folks.

“The recommendations are going to be that everybody gets vaccinated because that way we know — across vulnerable groups and all ages and different demographics — they’ll all get a robust immune response.”

Veillette adds that many people with previous COVID cases were also in higher-risk settings — either because of their jobs or living environments — that would theoretically put them at risk for reinfection.

And if they were to get the virus again but not show symptoms, they could still pass it on to other people.

“There’s probably a whole spectrum of situations there, and when there’s so many variables it’s better to have a simple rule,” he said. “So I think that’s another reason to vaccinate previously infected people.”

Melissa Couto Zuber, The Canadian Press


Like us on Facebook and follow us on Twitter.

Want to support local journalism during the pandemic? Make a donation here.

Coronavirusvaccines

Get local stories you won't find anywhere else right to your inbox.
Sign up here

Just Posted

The campground will be inside Quesnel, where the public works building used to be. (City of Quesnel Riverfront Plan)
Quesnel municipal campground project receives $500K in provincial funding

$20 million in funding was given to shovel-ready tourism projects across the province

A timing board was set up so skiers could record their own times. Savannah Robinson, who competes in biathlon as well, got a chance to test her skiing power. She came in second in the 20km classic race. (Cassidy Dankochik Photo - Quesnel Cariboo Observer)
Cariboo Ski Touring Club ‘So-Lo-Ppet’ results

The Quesnel cross-country skiing group was forced to change because of COVID

Members of the Quesnel RCMP Detachment wore their best pink shirts to support anti-bullying efforts. (Back row – Constable Sean Terry, Sergeant Rirchard Weseen, Constable Bob Kalman, Constable Alyssa MacNeil Middle – Constable Doug Erickson, Patti Thompson, Cindy Osip, Constable Cody Brown Front – Dana Bouchard, Staff Sergeant Darren Dodge, Kellie Hipkin) (Karen Powell Photo - Quesnel Cariboo Observer)
Quesnel RCMP goes pink in effort to stop bullying

Officers and staff from the detatchment participated in Pink Shirt Day

FILE – A COVID-19 vaccine being prepared. (Olivia Sullivan/Sound Publishing)
B.C. seniors 80 years and older to get COVID vaccine details over next 2 weeks: Henry

Province is expanding vaccine workforce as officials ramp up age-based rollout

Jacob Bowden competes at the 2020 Provincial High School Rodeo in Quesnel. The Quesnel student was named to the provincial (Karen Powell Photo - Quesnel Cariboo Observer)
Jacob Bowden named to high school Cinch team

The Quesnel grade eight student was named to the team in 2020 as well

Dr. Bonnie Henry talk about the next steps in B.C.'s COVID-19 Immunization Plan during a press conference at Legislature in Victoria, B.C., on Friday, January 22, 2021. THE CANADIAN PRESS/Chad Hipolito
456 new COVID-19 cases in B.C., 2 deaths

Since January 2020, 78,278 have tested positive for the novel coronavirus in B.C.

NDP leader Jagmeet Singh holds a press conference on Parliament Hill in Ottawa on Wednesday, Feb. 24, 2021. THE CANADIAN PRESS/Sean Kilpatrick
NDP will not trigger election as long as pandemic continues: Singh

‘“We will vote to keep the government going’

“Support your city” reads a piece of graffiti outside the Ministry of Finance office. (Jane Skrypnek/News Staff)
Slew of anti-bylaw graffiti ‘unacceptable’ says Victoria mayor, police

Downtown businesses, bylaw office and Ministry of Finance vandalized Wednesday morning

A health-care worker prepares a dose of the Pfizer-BioNTech COVID-19 vaccine at a UHN COVID-19 vaccine clinic in Toronto on Thursday, January 7, 2021. (THE CANADIAN PRESS/Nathan Denette)
Vaccinating essential workers before seniors in B.C. could save lives: experts

A new study says the switch could also save up to $230 million in provincial health-care costs

The late Michael Gregory, 57, is accused of sexually exploiting six junior high students between 1999 and 2005. (Pixabay)
Former Alberta teacher accused of sexually assaulting students found dead in B.C.

Mounties say Michael Gregory’s death has been deemed ‘non-suspicious’

According to a new poll, a majority of Canadians want to see illicit drugs decriminalized. (THE ASSOCIATED PRESS)
Majority of Canadians think it’s high time to decriminalize illicit drugs: poll

More than two-times the B.C. residents know someone who died from an overdose compared to rest of Canada

Photograph By @KAYLAXANDERSON
VIDEO: Lynx grabs lunch in Kamloops

A lynx surprises a group of ducks and picks one off for lunch

(Black Press Media file photo)
B.C. residents can reserve provincial camp sites starting March 8

B.C. residents get priority access to camping reservations in province

Most Read