Protected? Unprotected? COVID-19 experts warn of definition dangers as N.B. reviews policy

Three months after New Brunswick said it was looking at revising how it defines vaccine protection from COVID-19, the Department of Health says it's still working on it.

Some experts CBC News spoke to are not surprised. They say it's challenging, both scientifically and politically.

They also warn the current approach is misleading, could fuel anti-vaccine sentiment, and could further drive the anticipated surge in COVID activity this fall and winter.

"If we're not doing anything to update everyone's understanding, we're continuing to essentially propagate this mess," said Colin Furness, an infection control epidemiologist and assistant professor with the faculty of information at the University of Toronto.

For months, New Brunswick's rates of hospitalization and death from COVID-19 have been higher for those "protected" from the virus than those "unprotected," according to the province's weekly COVIDWatch reports.

I think while they're dithering, we're actually maximizing health harm.- Colin Furness

Of the 1,640 COVID hospitalizations recorded since Dec. 5, 2021, the rate among the protected was 55.7 per 100,000, compared to 44.3 among the unprotected, as of last week's report.

Of the 451 COVID deaths recorded during the same period, the rate among the protected was 69.4 per 100,000, compared to 49 per 100,000 among the unprotected.

But the province lumps people who have had two vaccines and a booster dose more than six months ago in with those who haven't had a single shot.

It defines "protected" as being boosted or fully vaccinated within the last six months, while "unprotected" refers to being fully vaccinated for more than six months, being partially vaccinated or being unvaccinated.

Although the immunity of someone who received a third dose more than six months ago may have waned, it's still better than someone who hasn't had any vaccination, said Rod Russell, professor of immunology and virology with the faculty of medicine at Memorial University in Newfoundland and Labrador.

The protected definition doesn't include people with protection from a previous infection either, Dr. Yves Léger, acting chief medical officer of health, has said.

"The Department of Health is reviewing those definitions at this time," said spokesperson Abigail McCarthy. "We may have more to share on the topic in the future."

Terminology challenged

Russell contends it's "impossible" to define protected or unprotected vaccination status. "I'm surprised they're even considering continuing using that terminology," he said. 

Russell notes some jurisdictions have even moved away from using the term "fully vaccinated," which commonly referred to two doses, since some people are now on their third booster.

"I don't think you can define … an individual's immune status at this point based on how many shots they've had," said Russell, "because you don't know how well they respond to the vaccine, you don't know how severe their symptoms were [if] they got infected, you don't know how many times they've been infected unless they were testing, and people aren't testing as much as they used to be."

The Public Health Agency of Canada reports the percentage of people who have, in the last six months, "completed the primary series or received a booster dose."

Russell isn't "a fan" of using the six-month timeline either.

It "made sense" a year ago when people seemed to be getting six months protection from infection with previous COVID strains, such as Delta, he said. With the more recent Omicron subvariants BA.4 and BA.5, however, some people have been reinfected as little as six weeks after their last booster, he said.

Creates misconceptions, false sense of security

Continuing to report COVID statistics in New Brunswick's current way, which makes it appear as if those who have been vaccinated are more likely to be hospitalized and die from COVID, could be dangerous, suggested Russell.

It creates misconceptions about vaccines, which he described as "a little infuriating" to see spread on social media, when really it's mostly about high vaccination rates and math.

Vaccinated people far outnumber unvaccinated people, said Russell, and those most likely to be vaccinated and boosted are older because they're more vulnerable to COVID, but also more likely to get severely ill and die.

Within that group will be people who don't mount a good immunity response to the vaccine, but that doesn't mean vaccines aren't working, he stressed.

According to a study published in the Lancet, vaccines have averted nearly 20 million deaths worldwide.

The other potential danger of the province's current definitions of protected and unprotected is they create a false sense of security, said Russell.

"If you think you can't possibly be infected because, you know, you've got this protective status, then you run the risk of infecting others," he said, citing as an example someone deciding not to mask in a long-term care home, only to later discover they were infected.

The risk of exposure is also higher now, noted Russell, with no protective measures, such as masking or distancing, in place, and the dominant strains being the highly transmissible Omicron variants. So while some people didn't get infected before, even if they didn't have a good immune response, because they weren't exposed, he believes more vulnerable people will get sick and die.

Shift in goal

Furness believes the first point of uncertainty in the province redefining protection is that while people maintain "really good protection" against severe illness and death after two doses, effectiveness "wanes down very low" when the measure is symptomatic infection.

"Both measures matter, but they're different," he said.

Similarly, data shows a third dose provides "noticeably better long-lasting protection" against severe illness and death, and protects against infection, but only for a brief period of time before it fades again.

"So I think … part of the problem is, what's the goal of the vaccine now? It used to be to prevent transmission and it's not very effective at doing that unless you continue to get boosted," said Furness.

"So scientifically, logically, we would either say this is a three-dose vaccine, in terms of the jump in improvement performance after a third booster for long term effects."

Or "we could … say that this is a vaccine you need to subscribe to, and you need to have a booster, it looks like about every three months, if you want to maintain maximum protection against infection. That's politically unpalatable," he said.

Furness believes that's why the province is still studying the issue.

"They're not waiting for more data," he said. "I think they're trying to figure out what to do politically that is going to minimize political harm.

"And I don't like that because I think while they're dithering, we're actually maximizing health harm."

That harm, he said, is "everyone's belief that they're fine, that they're 'protected,' in finger quotes, and that we don't need to do anything else."

That has led to "massive" transmission of COVID-19, hospitalizations, an estimated 10 to 15 per cent of the workforce off sick, a labour shortage which is partly driving inflation, and deaths, said Furness.

"So we've got social, health and economic consequences that are horrible."

Furness recommends the province consider adopting the "fully vaccinated" terminology and define it as having three doses, regardless of whether they're monovalent or bivalent vaccines. That would mean focusing on preventing severe illness and death from COVID, he said.

While Furness would like to see the province focus on preventing transmission as well, he contends that would require multiple measures, such as indoor air quality improvements and at least some masking mandates.

"In terms of policy, it's pretty hard to defend compelling frequent boosters when we're not doing anything else to stop transmission, because those boosters on their own, they just won't be effective," he said.