Is ‘natural’ immunity enough for a COVID passport?
Recent studies suggest immunity gained through a previous infection can provide formidable protection against Delta
As Ontario and New Brunswick become the latest provinces to require proofof-vaccination for entry to select settings, making life less comfortable for the unvaccinated, some are asking: Should exceptions be made for those who have already had COVID-19?
Alberta Premier Jason Kenney has “asked our folks” to work on a system similar to Israel’s green pass scheme, which recognizes the recovered as having immunity against SARS-CoV-2, “because I do acknowledge — we acknowledge — the science of the strong level of protection through antibodies acquired from prior infection,” Kenny said during a recent live Facebook Q &A.
With a record number of COVID patients in hospital, Alberta simply can’t wait to “onboard” proof of antibodies to its proof-of-vaccination program, Kenney said. The logistics, for now, would be unworkable, the premier said. He also noted that recent studies suggest the strongest level of protection is a hybrid, one-two punch — infection, plus vaccination that gives one “COVID superpowers.”
However, “if we can come up with a practical system that incorporates (the previously infected) I’m very open to doing so, on expert advice,” Kenney said.
Canadian country music star and COVID-recovered Paul Brandt triggered robust debate soon after with a long Facebook post arguing that people who have had a prior infection should be recognized as sufficiently immune and worthy of “the blessing” of a COVID restriction exemption. “Currently, the fact that I am COVIDrecovered and unrecognized in the system only serves to push me into the marginalized ‘unvaccinated’ category,” said Brandt. He said he wasn’t against vaccines and encouraged the unvaccinated to strongly consider getting vaccinated. “Trust me, COVID19 is not fun.” But “why aren’t people who are COVID-recovered being included in the conversation?” University of Saskatchewan virologist Angela Rasmussen reached out to Brandt via social media, and later participated in a Zoom call with the singer and his wife. Rasmussen described how variable immunity from an infection can be, and how one dose of a vaccine can reliably give people previously infected high levels of neutralizing antibodies. “She has convinced me,” Brandt told CBC radio’s The Homestretch this week. “I think it’s very important for us to have these hard conversations.”
Discussions around “natural” immunity, however, have been taboo. Officials worry it could lead to some willfully choosing to get the infection over a COVID-19 vaccine, risking serious consequences, like hospitalization, long COVID, or death, and that it muddies the pro-vaccine messaging.
However, recent studies also suggest immunity gained through a previous infection can provide formidable protection against SARS-CoV-2 — those who have been previously infected and then vaccinated may be the best protected of all. Some COVID-recovered ask whether it’s fair they risk being shut out of non-essential businesses, or terminated from their jobs, unless they agree to be vaccinated.
The issue is complicated, and worthy of discussion, said Matthew Miller, an associate professor in the Michael G. DeGroote Institute for Infectious Diseases at McMaster University in Hamilton.
“There are some important practical considerations, in additional to medical/scientific ones,” Miller said in an email.
First, it’s harder to document and confirm a previous infection than to track vaccination. Early in the pandemic, when testing centres were overwhelmed, many people were diagnosed with “COVID-19” based on symptoms only. But other viruses can cause similar symptoms, meaning “there is a considerable risk that someone who was misdiagnosed would remain vulnerable to infection while assuming they are immune,” Miller said.
Even if only lab-confirmed prior infections were considered, “problems linger,” Miller said. As testing capacity increased, testing was offered to anyone who wanted one, even if they had no symptoms. But studies have shown that those who have asymptomatic, or mild infections mount a considerably less robust immune response than those who had symptoms, Miller said, “and also less robust than those who have received a full vaccine series.”
With no clear safety signals associated with inoculating the previously infected that he’s aware of, Miller said it seems prudent to require the same proof-of-vaccination for the COVID recovered from a policy standpoint.
Delta further complicates the picture, said Rodney Russell, professor of virology and immunology at Memorial University of Newfoundland. People infected very early in the pandemic would have made responses to the earlier, weaker variants. “So, do we know they can handle more recent variants months, or potentially years, after their original infection?”
Still, two recent studies suggest immunity from a previous infection confers longer-lasting and stronger protection against SARSCoV-2. A large study of tens of thousands of Israelis, a preprint that hasn’t yet been peer reviewed, found that people who never had COVID and received two doses of the Pfizer shots were six to 13 times more likely to contract Delta than those who were previously infected with COVID.
However, in another analysis from the same study, the COVID-recovered who remained unvaccinated were twice as likely to be re-infected as the COVID-recovered who received a single dose of the Pfizer-BioNTech vaccine. Others have shown that people with a previous SARS-CoV-2 infection “mount unusually potent immune responses to COVID19 vaccines,” virologist Shane Crotty wrote in Science magazine, which may explain why they are also more likely to experience side effects like fever and fatigue.
A study out of Rockefeller University published in Nature, meanwhile, found that memory B cells that can linger for decades and unleash potent antibodies every time the body is re-exposed to SARS-CoV-2 outperformed memory B cells produced by mRNA vaccines.
With natural infection, the immune system sees the whole virus, not just the spike protein that’s generated from the vaccines. But natural infection “can also kill you,” Rockefeller’s Michel C. Nussenzweig told the university’s magazine.
The messaging, therefore, has been that everyone should get vaccinated, regardless of previous infection, and no one should intentionally attempt to get infected.
“Back before we even knew we’d have vaccines so soon, many countries and groups who were strongly opposed to lockdowns and public health measures were using the argument that the quickest way to establish herd immunity and get back to normal would be let the virus run wild — a reckless approach that would have resulted in far more deaths than we have already seen,” Russell, of Memorial University, wrote in an email.
“Having said that, personally I feel immunity is immunity, and immunity from natural infection contributes to herd immunity in the same way that vaccine-induced immunity contributes to herd immunity. But I DEFINITELY don’t think anyone, anywhere should have ‘ripped off the Band-Aid’ to quickly establish herd immunity.”
Still, the anti-vaccine community has embraced the idea of natural immunity, arguing that the value of natural immunity has been ignored. “The argument is, ‘See, they don’t really care about the science, all they care about is their vaccine agenda.’ It’s really kind of a stealth way to critique vaccine policy,” said University of Alberta health policy expert Timothy Caulfield.
The more explicit claim is that natural immunity is better, he said. “Natural immunity has become an antivaxxer talking point.”
Still, the anti-vaccine community has embraced the idea of natural immunity, arguing that the value of natural immunity has been ignored.
“The argument is, ‘See, they don’t really care about the science, all they care about is their vaccine agenda.’ It’s really kind of a stealth way to critique vaccine policy,” said University of Alberta health policy expert Timothy Caulfield