COVID-19 vaccines working despite infections among 'protected,' says virologist

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More than three quarters of the new PCR-confirmed cases of COVID-19 reported in New Brunswick on Tuesday were among people who had received their booster shot or were fully vaccinated for less than six months. (Ryan Remiorz/The Canadian Press - image credit)
More than three quarters of the new PCR-confirmed cases of COVID-19 reported in New Brunswick on Tuesday were among people who had received their booster shot or were fully vaccinated for less than six months. (Ryan Remiorz/The Canadian Press - image credit)

A virology expert says COVID-19 vaccines are doing their job, despite the fact that vaccinated people are contracting the virus.

Of the 1,988 New Brunswickers who tested positive for COVID through PCR lab tests between April 17 and April 23, 76.4 per cent were "protected," figures released by the province Tuesday show.

The province defines protected as boosted or fully vaccinated less than six months.

Rodney Russell, a professor of virology and immunology at Memorial University of Newfoundland, says vaccines are working like they're supposed to.

"They're not keeping you from getting infected very well. But the fact that your body saw the vaccine before you got infected meant that your infection wasn't going to be as bad as it would have been if you hadn't been vaccinated," he said.

"And even now, if you get infected and then reinfected, basically, the more times your body sees the vaccine and or the virus, the more immunity you're building up inside your body. And theoretically, and I think practically, the better you'll deal with that every time."

Government of New Brunswick
Government of New Brunswick

The vaccination status of the six latest COVID-related deaths and 87 people currently hospitalized because of the virus is not provided on the province's new COVIDWatch web page.

But of the 236 deaths recorded since Dec. 5, 52.1 per cent were protected and 47.9 per cent were unprotected, which the province defines as fully vaccinated more than six months, partially vaccinated, or unvaccinated.

Of the 908 people hospitalized during the same period, 46.8 per cent were protected and 53.2 per cent were unprotected.

Among the ICU cases alone, 34.8 per cent were protected and 65.2 per cent were unprotected.

A total of 51.9 per cent of eligible New Brunswickers have now received their COVID-19 booster dose, up from 51.8 per cent a week ago, 87.8 per cent have received two doses, unchanged, and 93.1 per cent have received their first dose, also unchanged.

The province started offering second booster doses last week to New Brunswickers aged 50 or older, if at least five months have passed since their last dose.

The rollout of second boosters for nursing home residents started this week and plans for other long-term care residents are in the works, the Department of Social Development says.

Best antibody response

People who are vaccinated and then contract the virus have "the best of both worlds" in terms of antibody response, said Russell.

That's because the vaccines only contain the outer spike protein of the virus, he said, so the antibody response is directed at that.

"Once you get infection, then you'll actually have antibodies and T-cell responses against many other parts of the virus. So you'll have a broader reaction.

"Now, that doesn't mean you'll have a better immune response against the virus than you would against a vaccine, because there's a lot more variability in your response against the virus than there is against the vaccine," noted Russell. But they will complement each other.

Memorial University of Newfoundland
Memorial University of Newfoundland

In addition to a person's vaccination status, the likelihood of catching COVID-19 a second time also depends, in part, on how much virus is in the community and the time of year, said Russell.

"There's no doubt that this, you know, is one of those seasonal viruses, and it should go down in prevalence a little bit now as spring comes," he said.

How long ago people were last infected is also a factor, Russell said.

Scientists originally believed there was 90-day period after infection when a person would be immune to the virus, he said.

But once the Omicron variant emerged, that dropped to about 60 days.

It's very rare. But there's no doubt that if you've been infected, three months later, you could get infected again. - Rodney Russell, virologist and immunologist

"Now we're even seeing, you know, rare cases where people are getting reinfection as little as … 30 to 40 days after they've been infected," said Russell.

"It's very rare. But there's no doubt that if you've been infected, three months later, you could get infected again."

The number of new COVID-19 cases across the province dropped to 3,964, according to Tuesday's report, from 5,645 the previous week.

That includes the 1,988 PCR-confirmed cases, as well as 1,976 people who self-reported testing positive on rapid tests.

Based on the PCR tests alone, there are now 3,134 active cases across the province.

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