A lady wears a vaccinated sticker after receiving a COVID-19 vaccine at a vaccination clinic run by Vancouver Coastal Health, in Richmond, B.C., Saturday, April 10, 2021. THE CANADIAN PRESS/Jonathan Hayward

A lady wears a vaccinated sticker after receiving a COVID-19 vaccine at a vaccination clinic run by Vancouver Coastal Health, in Richmond, B.C., Saturday, April 10, 2021. THE CANADIAN PRESS/Jonathan Hayward

Canada may find it challenging to reach herd immunity from COVID-19, experts say

Level of immunity among the population changes with the variants, especially the more transmissible strains

Herd immunity may not be reached in Canada but a return to life similar to that before COVID-19 is possible through immunization, experts say.

Such immunity is achieved when enough people are immune to a virus, either through vaccinations or natural infections or a combination of both.

Prof. Paul Tupper of Simon Fraser University’s mathematics department said herd immunity is unlikely to happen with COVID-19 for a few reasons.

The virus is being transmitted worldwide, which means it is reintroduced in different places across borders and immunity through vaccination and infection doesn’t last permanently. The vaccines don’t seem to be completely effective against some of the new variants, he said.

“So, I think what is more likely to happen is that we end up in a situation like we have with seasonal flu,” Tupper said.

“We have to live with the flu, and I think something similar is going to happen with COVID.”

The level of immunity among the population also changes with the variants, especially the more transmissible strains, he said.

Sarah Otto, a University of British Columbia professor, said the disease’s reproductive rate is hard to pinpoint, which makes it difficult to establish a herd immunity target. Otto is an expert on the mathematical models of pandemic growth and control in the university’s zoology department.

The reproductive rate is the number of additional people infected by a single person with COVID-19, which has also changed because of the variants, she said.

Canada might also fall short of herd immunity because people can still get infected after vaccination, even if they are less likely to develop symptoms, she said.

“We don’t yet know how effective vaccines are at reducing transmission from person to person and that matters a lot,” Otto said.

Vaccinated people are getting fewer infections but those who do can still suffer severe symptoms, she said

“Before the pandemic, we didn’t have working vaccines for coronaviruses, so we don’t know exactly what the outcomes are going to be. It’s very unusual to have a disease with such wildly differing outcomes, with asymptomatic individuals and severely affected long haulers. How are vaccines going to change that mix? We don’t really know why the severe cases are so severe.”

Tupper said public health guidelines will change as more people get vaccinated.

“But the goal of eradicating COVID just does not appear to be realistic.”

Dr. Isaac Bogoch, an infectious disease specialist at the University of Toronto, said vaccines can significantly reduce transmission rates, regardless of whether Canada reaches herd immunity.

“Some communities might have no transmission while other communities, even within the same province, might have some low levels of transmission and it’s all based on vaccine status,” he said.

“But regardless, we will achieve very, very low rates of transmission in our communities because of vaccination.”

Community level immunity is when a virus is not completely eliminated, he said.

“There may be some transmission of COVID-19 but sporadically with small outbreaks or with low levels of transmission, while most people are largely unaffected due to widespread vaccination.”

It had been suggested that herd immunity could be reached when about 70 per cent of the population is vaccinated, but now researchers don’t know what level of protection is required because of the variants.

Otto said there are more questions than answers at this point.

“With every partial answer we get two or three more questions. These are hard and tricky issues and I wish we were less uncertain, but that is the truth of the matter.”

READ MORE: B.C. ‘should be able to’ offer 1st dose of COVID vaccine to kids 12+ by end of June

Hina Alam, The Canadian Press


Like us on Facebook and follow us on Twitter.

Coronavirus

Just Posted

Storm clouds gathered in Mulhurst, Alta., just before noon June 15, 2021. Photo/ Dan Moster.
Areas of County of Wetaskiwin remain under severe thunderstorm watch

Environment Canada has issued a severe thunderstorm watch for areas of the County.

Maskwacis Pride crosswalk (Left to right): Montana First Nation Councillor Reggie Rabbit, Samson Cree Nation Councillor Louise Omeasoo, Samson Cree Nation Councillor Katherine Swampy, Samson Cree Nation Councillor Shannon Buffalo, Samson Cree Nation Chief Vern Saddleback.
Pride in Maskwacis

The 4th inaugural Maskwacis Pride crosswalk painting took place on Saturday June 12th, 2021

The Government of Alberta identified 115 new COVID-19 cases Sunday, bringing the provincial total to 3,089.
(Black Press file photo)
Red Deer COVID cases continue to fall

114 cases in Red Deer, down one from Saturday

Manluk Centre/ Impress
Manluk Centre re-opens to the public

Drop in and registered programs will be available; one-third facility capacity to be followed.

File photo
Leduc RCMP request assistance to identify armed robbery suspect

Leduc RCMP are looking for male responsible for an armed robbery at Super Car and RV Wash in Leduc.

People watch a car burn during a riot following game 7 of the NHL Stanley Cup final in downtown Vancouver, B.C., in this June 15, 2011 photo. THE CANADIAN PRESS/Geoff Howe
10 years ago: Where were you during the 2011 Vancouver Stanley Cup Riots?

Smashed-in storefronts, looting, garbage can fires and overturned cars some of the damage remembered today

Tulips bloom in front of the Supreme Court of Canada in Ottawa, Thursday, May 10, 2018. Day two of a full week of scheduled hearings will be heard in Federal Court today on a case involving Indigenous children unnecessarily taken into foster care by what all parties call Canada’s “broken child welfare system.” THE CANADIAN PRESS/Sean Kilpatrick
AFN slams Ottawa for ‘heartless’ legal challenge of First Nations child compensation

2019 decision awarded $40,000 to each Indigenous child removed before 2006

A health-care worker holds up a sign signalling she needs more COVID-19 vaccines at the ‘hockey hub’ mass vaccination facility at the CAA Centre during the COVID-19 pandemic in Brampton, Ont., on Friday, June 4, 2021. This NHL-sized hockey rink is one of CanadaÕs largest vaccination centres. THE CANADIAN PRESS/Nathan Denette
‘Vaxxed to the max’: Feds launch Ask an Expert campaign to encourage COVID shots

Survey shows that confidence in vaccines has risen this spring

Children’s shoes and flowers are shown after being placed outside the Ontario legislature in Toronto on Monday, May 31, 2021. THE CANADIAN PRESS/Frank Gunn
Ontario commits $10 million to investigate burial sites at residential schools

Truth and Reconciliation Commission identified 12 locations of unmarked burial sites in Ontario

Two hundred and fifteen lights are placed on the lawn outside the Residential School in Kamloops, B.C., Saturday, June, 13, 2021. The remains of 215 children were discovered buried near the former Kamloops Indian Residential School earlier this month. THE CANADIAN PRESS/Jonathan Hayward
Days after Kamloops remains discovery, Tk’emlups families gather to unite, move ahead

‘We have to work together because this is going to be setting a precedent for the rest of the country’

In this Saturday, May 29, 2021, file photo, people crowd the Santa Monica Pier in Santa Monica, Calif. California, the first state in America to put in place a coronavirus lockdown, is now turning a page on the pandemic. Most of California’s coronavirus restrictions will disappear Tuesday, June 15, 2021. (AP Photo/Damian Dovarganes, File)
With COVID tamed, it’s a ‘grand reopening’ in California

No more state rules on social distancing, no more limits on capacity, no more mandatory masks

Montreal Canadiens goaltender Carey Price (31) is scored on by Vegas Golden Knights defenseman Alec Martinez, not pictured, during the second period in Game 1 of an NHL hockey Stanley Cup semifinal playoff series Monday, June 14, 2021, in Las Vegas. (AP Photo/John Locher)
Habs fall 4-1 to Vegas Golden Knights in Game 1 of NHL semifinal series

Match was Montreal’s first game outside of Canada in 2021

The Kamloops Indian Residential School is photographed using a drone in Kamloops, B.C., Monday, June, 14, 2021. The remains of 215 children were discovered buried near the former school earlier this month. THE CANADIAN PRESS/Jonathan Hayward
Communities grapple with what to do with former residential and day schools

Some tear them down as a tool to help healing, others repurpose them as tools for moving forward

RCMP Const. Shelby Patton is shown in this undated handout photo. RCMP say that Patton was hit by an allegedly stolen truck that he had pulled over on Saturday morning in Wolseley, east of Regina. THE CANADIAN PRESS/HO, RCMP
Pair charged in Saskatchewan Mountie’s death make first court appearance

Const. Shelby Patton was hit by an allegedly stolen truck that he had pulled over Saturday morning

Most Read