Nova Scotia

Herd immunity alone may not protect you from COVID-19, say experts

Two experts in vaccines and immunology are urging Nova Scotians to get vaccinated against COVID-19 as soon as possible because herd immunity alone may not be enough to protect those who aren't immunized.

'It's going to be months before we have a new normal,' says Dr. Scott Halperin

Dr. Scott Halperin is the director of the Canadian Centre for Vaccinology. (Brooklyn Currie/CBC)

More than 325,000 people, roughly three in 10 Nova Scotians, have received at least one dose of COVID-19 vaccine.

But two experts say that is not enough to have an effect on the spread of the virus across the province.

"We need to get up closer to 50 to 60 per cent before we can really see that," said Dr. Scott Halperin, the director of the Canadian Centre for Vaccinology in Halifax. "We're well on our way to that.

"Hopefully, we'll start seeing that effect soon."

Part of the problem, according to Halperin, is that few people were infected during the first two waves of the pandemic. As a result, Nova Scotians have had to rely on vaccines for protection. 

He said had the third wave arrived after more people had their jabs, we might have been spared community spread in the Halifax area.

"If that could have been held off for another three or four weeks we might have gotten to the point where we wouldn't have seen this surge," he said.

'The vaccine should do just fine'

This surge is being driven primarily by the variant strain first detected in the U.K., but Halperin said the three vaccines currently available in Nova Scotia offer enough protection against it.

"The vaccine should do just fine," said Halperin. "What the future holds? That's what we don't know."

Halperin said the race is on to protect enough people before the virus mutates to the point where current vaccines provide so little protection that new vaccines have to be created to deal with the new strains.

Dr. Rodney Russell is an immunology and virology professor at Memorial University of Newfoundland. (Memorial University of Newfoundland)

Meanwhile, Dr. Rodney Russell, an immunology and virology professor at Memorial University of Newfoundland, has a warning for those who think they don't need to be vaccinated because herd immunity will protect them against COVID-19.

"It's very, very important for people to realize that we may not be able to rely on herd immunity," he said. "If you want immunity, you have to get the vaccine yourself because I think the virus will find the unvaccinated people and keep spreading in them."

It's also unclear how many people will need to be vaccinated to create herd immunity or community protection, but Russell said the current thinking is that it will take at least 75 per cent of the population.

"Seventy-five per cent should give us enough immunity that we won't have massive outbreaks and explosions in cases like we see now in Halifax, like we saw in Newfoundland back in February," said Russell.

"If three-quarters of the population are vaccinated, then three out of four times that the virus tries to spread it gets blocked," he said. "So then you won't have outbreaks and that means we can have a normal life."

Disagreement on vaccinating children

But the two experts disagree when it comes to the importance of vaccinating children as part of the plan to protect all Nova Scotians.

Russell isn't concerned because children "for the most part ... haven't gotten that sick from this virus." 

"Usually if your symptoms aren't too bad, you're not spreading too bad either," he said.

Halperin takes a different view, suggesting the province will need to vaccinate as many people as possible, regardless of their age.

"Until we get down into children, 25 or so per cent of our population is staying fully susceptible, and while they may not have the most severe disease they may provide a sufficient susceptible pool to keep the virus circulating," he said.

Halperin said if the Nova Scotia government is able to remain on track to immunize at least 75 per cent of its population by the end of June, Nova Scotians should see a return to more normal activities.

"I think the new normal will be towards the fall, mid-fall, maybe," he said. "I think we have to hang in there."


With files from Information Morning


To encourage thoughtful and respectful conversations, first and last names will appear with each submission to CBC/Radio-Canada's online communities (except in children and youth-oriented communities). Pseudonyms will no longer be permitted.

By submitting a comment, you accept that CBC has the right to reproduce and publish that comment in whole or in part, in any manner CBC chooses. Please note that CBC does not endorse the opinions expressed in comments. Comments on this story are moderated according to our Submission Guidelines. Comments are welcome while open. We reserve the right to close comments at any time.

Become a CBC Member

Join the conversation  Create account

Already have an account?