‘Practical’ herd immunity for COVID-19 still a possibility, experts say

Jun 23, 2021 | News

Vaccines are integral to achieving a “practical herd immunity” in the fight against COVID-19, according to experts at Simon Fraser University. (Blair Gable/Reuters)

Herd immunity for COVID-19 might be a long shot but hope is not lost, according to two mathematics professors at Simon Fraser University in B.C.

Paul Tupper and Caroline Colijn, co-authors of an article for The Conversion, wanted to counteract previous media reports that suggested herd immunity was completely off the table.

“We don’t think that we’ll get [full herd immunity] for COVID for several reasons,” Tupper told Humber News in an interview. “But there is a practical herd immunity that we think is possible.”

This “practical herd immunity” is dependent on immunizations — either through vaccination or natural infection — and would allow a return to near-normal life, even while COVID-19 is still present to some degree.

“It’s not the absolute thing,” Tupper said. “But we can go back to a much more normal life.”

Pinpointing the exact percentage of immunized people necessary to achieve herd immunity is difficult for a number of reasons. Factors include changing transmissibility rates, new variants of concern, and the shifting availability of vaccines, Tupper said.

“[But] 90 per cent is a good goal that we can attain for our population,” he said.

Meaning, at least 90 per cent of our eligible population must be fully vaccinated for practical herd immunity to be achieved.

But that’s still a long way off, even with accelerated vaccine rollouts. To date, only 25 per cent of eligible Canadians — and 26 per cent of eligible Ontarians — are fully vaccinated.

Still, the best strategy is to stay the course and continue to vaccinate as many people as possible, Tupper said.

“In a sense, we are going to get to herd immunity one way or another,” he said. “And the better way to get it is through vaccination because COVID is not a safe way to get it.”

It will also be important to maintain the immunization level into the future, Tupper added.

“As we learn more about the virus and how it’s changing and how our immunity wanes, whether we’re infected or whether we were vaccinated, will we have to maintain that level of immunity,” he said.