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

Walnut Grove Secondary hosted a Terry Fox run on school grounds on June 4, 2021 in support of the Canadian icon’s foundation. Students ran a course on campus where they stopped at six stations to compete in a variety of challenges. (WGSS/Special to Langley Advance Times)
PHOTOS: Terry Fox run challenge amounts to $27,000 raised by Walnut Grove students

Local teacher pledged $25 donation for every student victory during student-teacher challenge

(Special to Langley Advance Times)
TRAFFIC: Crash on 200th Street in Langley

Emergency crews are on scene

Last year, strata president Rob Parker and his fellow owners were facing huge increases. This year, rates are down somewhat and owners are breathing a little easier. (Langley Advance Times files)
Strata insurance costs retreat after devastating spike in 2020

Many condos and townhouse complexes are getting a break after record hikes

Principal Chris Wejr and vice principal Mark Touzeau of Shortreed Elementary got all dressed up for their students in a tacky tourist greeting on Friday morning. (Michelle Greer/Special to The Star)
VIDEO: Tropical tacky tourists vacation at Shortreed Elementary

Staff dressed up on Friday morning and greeted students with grass skirts, sunglasses, and smiles

Otter Co-op. (Aldergrove Star files)
Co-op Community Spaces rebuilding community connections

Co-op is providing $1 million in funding for local projects as COVID-19 reopening gets underway

The border crossing on Highway 11 in Abbotsford heading south (file)
VIDEO: Western premiers call for clarity, timelines on international travel, reopening rules

Trudeau has called Thursday meeting, premiers say they expect to leave that meeting with a plan

The Abbotsford International Airshow is back for 2021 with the ‘SkyDrive’ concept.
Abbotsford International Airshow returns for 2021 with ‘SkyDrive’

New format features a drive-in movie type experience, show set for Aug. 6 to 8

People line up to get their COVID-19 vaccine at a vaccination centre, Thursday, June 10, 2021 in Montreal. THE CANADIAN PRESS/Ryan Remiorz
Vaccines, low COVID case counts increase Father’s Day hope, but risk is still there

Expert says people will have to do their own risk calculus before popping in on Papa

B.C. Premier John Horgan listens as Finance Minister Selina Robinson presents the province’s latest budget, April 20, 2021. The budget projects $19 billion in deficits over three years. (Hansard TV)
B.C. government budget balloons, beyond COVID-19 response

Provincial payroll up 104,000 positions, $10 billion since 2017

Cannabis bought in British Columbia (Ashley Wadhwani/Black Press Media)
Is it time to start thinking about greener ways to package cannabis?

Packaging suppliers are still figuring eco-friendly and affordable packaging options that fit the mandates of Cannabis Regulations

Ocean debris is shown on Long Beach in Tofino, B.C. on April, 18, 2012. THE CANADIAN PRESS/Jonathan Hayward
Shoreline cleanup finds COVID-related trash increased during height of the pandemic

Great Canadian Shoreline Cleanup reports litter from single-use food packaging nearly doubled

Doctor David Vallejo and his fiancee Doctor Mavelin Bonilla hold photos of themselves working, as they kiss at their home in Quito, Ecuador, Wednesday, June 9, 2021. Doctor Vallejo and Doctor Bonilla suspended their wedding in order to tend to COVID-19 patients and in the process Vallejo got sick himself with the disease, ending up in an ICU for several days. (AP Photo/Dolores Ochoa)
Love, sacrifice and surviving COVID-19: one couple’s story

COVID hits Ecuadorian doctors who delayed wedding to treat sick

Cover of the 32-page Surrey First Peoples Guide for Newcomers, created and compiled by Jeska Slater.
New ‘Surrey First Peoples Guide for Newcomers’ seeks to ‘uplift and amplify’ voices

32-page guide launched Tuesday by Surrey Local Immigration Partnership (LIP)

West Coast Duty Free president Gary Holowaychuk stands next to empty shelves inside his store on Tuesday (June 15). (Aaron Hinks photo)
Revenue down 97% at Surrey duty free as owner waits for U.S. border to reopen

Products approaching best before dates had to be donated, others destroyed

Most Read