A vaccination kit is seen during the setting up of a vaccination clinic in Montreal, on February 1, 2021. THE CANADIAN PRESS/Paul Chiasson

Fear that delayed second COVID-19 vaccine dose could lead to new variants ‘realistic’

Fear that delayed second COVID-19 vaccine dose could lead to new variants ‘realistic’

MONTREAL — Experts say delaying the second dose of some COVID-19 vaccines could lead to the emergence of new variants of the virus — but there’s no sign it has happened yet.

“It’s a theoretical, realistic possibility, but there is no evidence so far,” said Dr. Andre Veillette, a professor at the Universite de Montreal and the director of the Molecular Oncology Research Unit at the Montreal Clinical Research Institute.

Veillette, who is a member of the federal government’s COVID-19 vaccine task force, said there’s a concern that the immunity provided by one dose of the Pfizer-BioNTech and Moderna vaccines “is not as strong as you would get with two doses.”

That weaker immune response, especially in older people whose immune systems don’t respond as well to vaccines, “may favour the selection of variants,” Veillette said in an interview Wednesday.

Quebec has responded to Canada’s COVID-19 vaccine shortage by delaying the second dose of the two-dose vaccines. Public health director Dr. Horacio Arruda has said he believes that giving more people a single shot will save more lives than giving fewer people two doses.

Arruda has said he does not want the delay between shots to exceed 90 days — which would take the province well beyond the period recommended by vaccine manufacturers and the 42-day window recommended by the federal government’s National Advisory Committee on Immunization.

Dr. Caroline Quach, the chair of the committee, said in a recent interview that “there is a theoretical risk that if transmission is occurring at a higher rate in people who are partially vaccinated, or partially protected, with a very low protection, that variants could then develop that are going to be harder for vaccines to tackle.”

The committee judged that wasn’t a problem, because people should have sufficient protection in the first few weeks after they get vaccinated.

But, she added, “we might be wrong.” Without enough vaccine or enough data, the advisory committee is trying to make “the best educated guess.”

While Veillette said there is evidence the protection provided by one dose ofthe AstraZeneca vaccine — which has not yet been approved for use in Canada — lasts for more than three months, it’s a different type of vaccine than those developed by Pfizer and Moderna.

Jorg Fritz, an immunology professor at McGill University, said, “it’s absolutely a possibility” that suboptimal vaccination protocols could lead to increasing variants of COVID-19. He said he’s also worried that variant generation will happen among people who have chronic symptoms from COVID-19, so called “long COVID.”

But Fritz said that his greatest concern around delaying the second shot is that the single dose won’t be effective enough and that people will think the vaccine doesn’t work.

For Veillette, the biggest fear around the emergence of new variants isn’t the vaccine delay but the continuing spread of the virus around the world.

When the virus replicates, there’s a chance it will mutate, he said. While some of those mutations may be harmless — or even make the virus less infectious — some could make it more effective at infecting people.

“The more it is transmitted from one person to another, the more time elapses, the more you will get those mutations and the mutations that are advantageous for the virus,” he said.

That’s why it’s important to ensure that people around the world — and not just those in wealthy countries — are properly vaccinated, he said.

“I think it’s a mistake to think that because Canadians, or Americans or Europeans get well-vaccinated before others that this is going to make this disease go away and it’s going to prevent these people from having infections again,” he said.

This report by The Canadian Press was first published Feb. 3, 2021.

———

This story was produced with the financial assistance of the Facebook and Canadian Press News Fellowship.

Jacob Serebrin, The Canadian Press

Coronavirus

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

Just Posted

Lyn Radford, 2019 Canada Winter Games board chair, was named 2020 Sport Event Volunteer of the Year at the Prestige Awards. (File photo by Advocate staff)
WATCH: Lyn Radford wins award for volunteer efforts

The board chair of the 2019 Canada Winter Games in Red Deer… Continue reading

A candlelight vigil will be held in Red Deer on Thursday to honour the 350-plus people killed in the Easter bombing attack in Sri Lanka. Contributed photo
Candlelight vigil planned for deaths linked to Olymel COVID-19 outbreak

A candlelight vigil is being planned for those who died due to… Continue reading

Red Deer Rebels forward Jaxsen Wiebe battles Calgary Hitmen forward Cael Zimmerman for a loose puck when the two teams squared off in February last season. (Photo by BYRON HACKETT/Advocate Staff)
Calgary Hitmen shutout Red Deer Rebels

Rebels name centre Jayden Grubbe team captain ahead of Friday’s game

Traffic will be delayed on 40th Avenue and 19th Street until the end of February. (Advocate file photo).
Traffic delays expected downtown this weekend

Red Deer drivers will be delayed in the downtown area of the… Continue reading

Bryson, six, and Mara, eight, play with puppies from Dogs With Wings Saturday. (Photo by Sean McIntosh/Advocate staff)
WATCH: Dogs With Wings introduces Red Deer program

A program that trains puppies to be certified service, autism, facility and… Continue reading

Walter Gretzky father of hockey hall-of-famer Wayne Gretzky waves to fans as the Buffalo Sabres play against the Toronto Maple Leafs during third period NHL hockey action in Toronto on Tuesday, January 17, 2017. THE CANADIAN PRESS/Nathan Denette
Funeral for Walter Gretzky to be held Saturday in home town of Brantford, Ont.

The funeral for hockey legend Wayne Gretzky’s father Walter will take place… Continue reading

A sign for the Canadian Security Intelligence Service building is shown in Ottawa on May 14, 2013. A newly released audit report shows that difficulties with the judicial warrant process at Canada's spy agency — an issue that made headlines last summer — stretch back at least nine years. THE CANADIAN PRESS/Sean Kilpatrick
Spy warrant shortcomings stretch back almost a decade, newly released audit shows

OTTAWA — A newly released audit report shows that difficulties with the… Continue reading

In this file photo, a lotto Max ticket is shown in Toronto on Monday Feb. 26, 2018. (By THE CANADIAN PRESS)
No winning ticket for Friday night’s Lotto Max jackpot

TORONTO — No winning ticket was sold for the estimated $29 million… Continue reading

A trial countdown sign marks the days at George Floyd Square, March 4, 2021, in Minneapolis. Ten months after police officers brushed off George Floyd's moans for help on the street outside a south Minneapolis grocery, the square remains a makeshift memorial for Floyd who died at the hand of police making an arrest. The trial of former Minneapolis police officer Derek Chauvin will begin with jury selection on March 8. (AP Photo/Jim Mone)
Officer’s trial could reopen intersection where Floyd died

MINNEAPOLIS — During a group’s recent meeting at the now-vacant Speedway gas… Continue reading

FILE - In this Aug. 30, 2020 file photo Portland Police Chief Chuck Lovell calls for an end to violence in the city during a news conference a day after a demonstrator was shot and killed in downtown Portland. Amid protests following the police killing of George Floyd last year Portland dissolved a special police unit designed to focus on gun violence. Critics say the squad unfairly targeted Black people, but gun violence and homicides have since spiked in Oregon's largest city, and some say disbanding the 35-officer unit was a mistake. (Sean Meagher/The Oregonian via AP, File)
As violence surges, some question Portland axing police unit

PORTLAND, Ore. — Elmer Yarborough got a terrifying call from his sister:… Continue reading

Harley Hay
Harley Hay: Just don’t call it cod liver oil

Many people swear that a daily dose of various vitamins is an… Continue reading

Email editor@auburn-reporter.com
Letter: Preserving green spaces in Red Deer

The Advocate published an article Feb. 11 about Sunnybrook residents concerned about… Continue reading

Former Toronto Argonauts lineman Chris Schultz remembered as a gentle giant

Former Toronto Argonauts lineman Chris Schultz remembered as a gentle giant

Most Read