In the early dark days of the pandemic, when vaccines for what was then still sometimes called the new coronavirus were just hope, researchers around the world began to notice a strange phenomenon.
A family member came to the hospital with a loved one who was struggling to breathe or was connected to a ventilator. But instead of getting sick, this man seemed to have somehow escaped the virus.
“Wait a minute. You live in the same house, in the same bed, you do everything together – he’s in the intensive care unit, and you’re not? “Said Dr. Donald Vinn, an infectious disease specialist and medical microbiologist at McGill University Health Center.
“It became very clear that there were people who had been exposed without a serious illness,” Vin recalls, but the “burning question” was whether they simply had no symptoms or had escaped the infection. And if so, how?
The sixth wave brought an explosion of COVID to some communities in Ontario, including Toronto, with many more friends and family members getting sicker than ever during the pandemic.
But for every story of someone who has come out with the virus, there seems to be another person who has been spared despite exposure, or even lives in the same house with many people who have tested positive. If you have bypassed COVID so far, you probably have vaccines, masks and good luck on your side, experts say.
However, there is a very small group of people who seem to have innate immunity to the virus. In fact, there is a precedent for this with other diseases, and Canadian researchers hope that unlocking the mystery of these “COVID resistors” could help develop more effective treatments and vaccines.
For the average person who hasn’t been infected, “it’s probably because you’re doing all the right things for public health,” said Dawn Boudish, a Canadian research chair on aging and immunity and a professor of medicine at McMaster University.
However, there are people there, probably less than one percent of the population, according to Boudish, who are “highly exposed but seronegative” – health workers, for example, who have been in COVID wards without proper masks before vaccines. Unlike individuals who received it and were asymptomatic, this elite group never develops antibodies in their blood against the virus (and scientists can tell if these antibodies are from the disease or the vaccine), having some natural immunity.
Boudish is the co-leader of a large study of COVID in long-term care and suggests that some people may have developed immunity after repeated exposure to other seasonal coronaviruses that cause the common cold.
“When exposed to SARS-CoV-2, they boost that immune response and somehow help protect themselves,” she said. Ninety-nine and nine percent of us, we have to rely on our antibodies to do some of this work, while these other people use what we call T-cells – another part of the immune system – that saw something very like months or years ago, and “take action and clean it up before it can even begin.”
McGill’s Vinh is the Canadian site leading an international investigation into the so-called “COVID resistors”, which began as an attempt to determine why some people get a severe bout of the disease. The team has identified about 700 people worldwide who qualify as exposed, negative tests (polymerase chain reaction (PCR) or rapid tests) and have never developed antibodies.
“We’re looking for the genetic basis for why people are resistant to COVID infection,” Vin said.
“If we can actually understand the molecular basis through which humans are naturally resistant to infections, this first step, when the virus tries to enter our cells, can guide the logical and rational development of therapies,” he added.
If you are still convinced that you are one of this small elite group, Vin and his team are still actively recruiting for their research.
In the UK, a research team has taken this a step forward in a so-called human challenge study, where 36 healthy, young unvaccinated adults were deliberately exposed to the virus. The main goal was to find the infectious dose needed for infection, but they also found that “interestingly, 50% of the volunteers were not infected,” said Dr. Andrew Ketchpool, chief scientist at hVIVO, the company that leads the study, recently published in Nature Medicine, in partnership with Imperial College London and the British government. Although they never expected anyone to become infected at low doses, they are currently studying the immune responses of those who have been infected against those who have not been infected in the hope that this may help find future drugs. , he added in an email.
After two years of “shot in the dark” with treatments, the idea with this kind of work is to start something that’s already happening in humans and move on, Vin said.
“Some people say it’s a bit exaggerated, that’s right, besides what science should be, it should be exaggerated,” he said. “But this is not unproven.”
Hundreds of years ago, when the plague was ravaging Europe, there were cases of people who simply never got it, even though they sometimes lost their whole family to the disease.
One theory is that people who survived the Black Death had a “specific mutation in one of their immune cells that makes them less likely to support the plague-causing bacteria,” says McMaster Boudish. Another famous example is a group of sex workers in Nairobi, Kenya, who have been exposed to HIV many times but have never been infected.
The message to most people who have avoided COVID so far is not to rely on this innate immunity as a hidden superpower, Boudish added. “But I think the inspiring part of finding people like that is that it kind of gives vaccine immunologists a hint of what to look for.”
Her McMaster colleagues, for example, are working on developing an inhaler vaccine that would ideally provide greater immunity against many variants of COVID, instead of vying to develop a specific vaccine each time the virus mutates.
“In a perfect world, our vaccines would do exactly what these people do naturally, rule out this infection before it even starts, and you will never carry it and you will never pass it on,” Boudish said. “And we will all be able to return to our lives in 2019.”
May Warren is a Toronto-based news reporter for Star. Follow her on Twitter: @ maywarren11
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