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

BC Green Party leader and Cowichan Valley MLA Sonia Furstenau introduced a petition to the provincial legislature on Thursday calling for the end of old-growth logging in the province. (File photo)
Cowichan Valley MLA Furstenau introduces old-growth logging petition

BC Green Party calls for the end of old-growth logging as protests in Fairy Creek continue

The city-owned lot at 361 St. Julien St., which has been home to a temporary homeless site for more than a year, will be sold and plans are to build a three-storey mixed-use development there, Peter de Verteuil, Duncan CAO explained at a recent council meeting. (File photo)
New development planned for homeless site in Duncan

Lot on St. Julien Street would see three-storey building

Historian and longtime Citizen columnist T.W. Paterson photographs the historical wreckage of a plane on Mount Benson. Paterson recently won an award from the British Columbia Historical Foundation. (Submitted)
Cowichan’s Tom W. Paterson wins award for historical writing

British Columbia Historical Federation hands Recognition Award to local writer

This electric school bus is the newest addition to the Cowichan Valley School District’s fleet. (Submitted)
Editorial: New electric school bus good place to start

Changing public transit like buses to electric really is important.

CVRD to increase enforcement after audits reveal that curb-side recycling contamination in the district is well above acceptable limits. (File photo)
CVRD reports contamination in recyclables well above acceptable levels

Increased enforcement planned starting this summer

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

The Calgary skyline is seen on Friday, Sept. 15, 2017. THE CANADIAN PRESS/Jeff McIntosh
2 deaths from COVID-19 Delta variant in Alberta, 1 patient was fully immunized

Kerry Williamson with Alberta Health Services says the two patients, a man and a woman likely acquired the virus in the hospital

B.C. Public Safety Minister Mike Farnworth and Attorney General David Eby attend opening of the first government-run B.C. Cannabis Store, Kamloops, Oct. 19, 2018. (B.C. government)
B.C. government to allow home cannabis delivery starting July 15

Added convenience expected to persuade buyers to ‘go legal’

The first suspension bridge is the tallest in Canada, with a second suspension bridge just below it. The two are connected by a trail that’s just over 1 km. (Claire Palmer photo)
PHOTOS: The highest suspension bridges in Canada just opened in B.C.

The Skybridge in Golden allows visitors to take in views standing at 130 and 80 metres

B.C. Premier John Horgan leaves his office for a news conference in the legislature rose garden, June 3, 2020. (B.C. government photo)
B.C. premier roasted for office budget, taxing COVID-19 benefits

Youth addiction law that triggered election hasn’t appeared

BC Ferries’ newest Island Class vessel is experiencing an issue with one of its thrusters off the Algerian coast. Photo courtesy patbaywebcam.com.
BC Ferries newest vessel having mechanical issues in Mediterranean

Island 4 will be repaired in Spain before crossing Atlantic

A vial containing the Moderna COVID-19 vaccine is shown at a vaccination site in Marcq en Baroeul, outside Lille, northern France, Saturday, March 20, 2021. THE CANADIAN PRESS/AP/Michel Spingler
mRNA vaccines ‘preferred’ for all Canadians, including as 2nd dose after AstraZeneca: NACI

New recommendations prioritizes Pfizer, Moderna in almost all cases

Surrey Mayor Doug McCallum speaks at a press conference in August 2019 about provincial government approval of the city’s change to a municipal force, joined by councillors (from left) Mandeep Nagra, Allison Patton and Doug Elford. Members of the National Police Federation claim there is still no transition plan in place although Surrey RCMP’s contract with the city is due to end March 31.(File photo)
Elections BC approves petition application for referendum on Surrey policing transition

Application was filed under Recall and Initiative Act by the widow of a Surrey murder victim

There were 255 babies born in Victoria in May 2021. (Black Press Media file photo)
Pandemic baby boom makes for a busier Vancouver Island Father’s Day

Victoria’s 255 babies born in May up almost 10 per cent over last year

Most Read