At this time of the pandemic, you are likely to have had COVID-19 at least once. Maybe twice. Maybe even three times, as some unfortunate Canadians have experiencedall the while this virus evolved to be increasingly skilled at infecting us.
It is clear that reinfections for this coronavirus are the norm, as is the case with those behind the common cold. Unfortunately, this also means that early speculation about occasional attacks of COVID-19 that offers immunity to future infections has long since come out the window.
What’s more blurry is how often you can get infected with SARS-CoV-2 and whether future infections will always be milder than the first ones, as the virus finds its way into our bodies over and over again.
Calmly, scientists say that for most healthy adults, including those with additional protection against vaccination, COVID-19 infections should be easier to treat as your immune system grows. get repeated training on how to handle this particular pathogen.
A transmission electron micrograph of SARS-CoV-2, isolated from a patient. Scientists say the virus is capable of reinfecting humans over and over again. But how often can it happen, and will it feel softer and softer? (National Institute of Allergies and Infectious Diseases)
“Your first infection with COVID will probably be, not invariably, but probably the worst,” said Dr. Allison McGeer, an infectious disease specialist who is a professor at the Dalla Lana School of Public Health at the University of Toronto.
“And then, as you expose yourself more and more, you get better and better protections.”
Coronaviruses attack repeatedly
After months or even years of completely avoiding the virus, you may be surprised that COVID-19 can affect you more than once.
In the early days of the pandemic, some scientists spread hopes around herd immunity: if enough people were caught or vaccinated against COVID-19, collective immunity to infection would reach a threshold where the virus could not. find new human guests.
Unfortunately, this is not easy with a coronavirus.
First identified in humans in the 1960s, viruses in this family have probably been hitting us repeatedly for centuries. SARS-CoV-2 is just the newest kid on the block.
“Four of these other family members cause about 30 percent of our common colds, and they routinely reinfect us,” said Dr. Amesh Adalja, a senior researcher at the Johns Hopkins Center for Health Security in Baltimore.
“We’ve all had several attacks of other coronavirus infections, and this is where this virus was always headed. So reinfections are not something to be surprised about.”
However, they were rare during the first part of the pandemic. SARS-CoV-2 is hitting people over and over again right now, two and a half years from here, in part because we give it a try.
“This would have been happening a lot more often if we hadn’t all been home and keeping our distance,” McGeer said. “It’s not that the virus is doing anything different than it would have done before; it’s that we’re behaving differently.”
Scientists say reinfections were rare during the early years of the pandemic, in part because people stayed home in large part, while more socializing is now giving the virus a chance to spread. (Marc-André Turgeon / CBC / Radio-Canada)
Layer increasingly contagious variants that are able to dodge frontline soldiers from our immune systems, and you’ll have a recipe for reinfections on a more regular basis. What is not clear is how often this virus will be affected.
Four long-lived seasonal human coronaviruses appear to be able to reinfect people every 12 months, according to research published in Nature Medicine which implied that scientists followed a group of healthy adults for more than 35 years.
But unlike this seasonal pattern, SARS-CoV-2 remains erratic: more of a constant roller coaster than of a large rise and fall in a given year.
In Canada and many other countries, a seventh wave is occurring, fueled by another evasive immune Omicron subvariant, BA.5. It is happening in the summer months, long before the typical cold and flu season, and not long after previous waves driven by other members of the Omicron family tree.
McGeer, like many close observers of COVID, is still unsure of which path this virus will take in the long run.
“Are we probably settling into winter activity? Yes, over time, but maybe not for another year or two,” he said. “Are you sure we’ll?”
Reinfections are usually no worse than the first
What several experts who spoke to CBC News are more confident about is that later COVID-19 infections should feel milder than early ones. That doesn’t necessarily mean a walk in the park, but at least not as hard as your body’s first encounter with this virus.
“For all the literature I’ve seen, when reinfections occur with increasing frequency, they don’t usually get worse,” said Angela Rasmussen, a virologist with the University of Saskatchewan’s Vaccine and Infectious Diseases Organization in Saskatoon. “And that’s exactly what you’d expect, because that’s how the immune system works.”
There are a couple of ways to train your immune system to fight this virus faster and smarter. One is directly exposed to SARS-CoV-2, which carries all the potential health consequences of an infection.
The other is to get vaccinated, allowing your body to know this particular pathogen without facing these risks. (Consider this option a martial arts lesson, rather than eliminating it in a surprise punch.)
Erin Wilson, a fitness teacher and actor in Halifax, has taken COVID-19 twice – the first time last December and again in July. Both times the virus hit her hard, causing fatigue, coughing and chest congestion, but she says the second time was a little easier. (Mark Crosby / CBC)
If you are vaccinated and take COVID-19, the virus could still pass through the first line of defense of your immune system, your neutralizing antibodies, and be introduced into your cells, Rasmussen said.
“Immediately, your vaccination memory T cells will say,‘ Wow, I’ve seen this guy before; it’s time to go out and start killing those cells that are infected with it, ”he explained.
In other words, a well-trained immune system cannot prevent infection, but it can often control it quickly. This means that an invader who could have wreaked havoc at some point simply does not have this opportunity.
So far, this has been the experience of Erin Wilson, a fitness teacher and actor in Halifax, who recently took COVID-19 again after first getting infected last December. (She is also vaccinated.)
The first lap left her exhausted and in bed for days, “completely incapacitated.” His next fight was not pleasant, and several days later, he was still struggling with chest congestion, cough, and fatigue, but he realized it was a little easier.
“The second time it didn’t knock me out so much,” Wilson said.
Not all reinfections will be “benign”
So, if you have already passed COVID-19 at least once before, should you throw caution to the wind and catch it over and over again? Not exactly.
The virus does not treat everyone equally, Johns Hopkins’ Adalja stressed. “What we’re learning is that not every second or third infection will be benign, and that will be especially true when it comes to higher-risk populations.”
A study focused on U.S. veterans -who are mostly older men- found that reinfections in this group appeared to have a higher risk of death or hospitalization.
The document, which has not yet been peer-reviewed, has been headlines in recent weeks. But several experts, including Adalja, warned not to read too much about his first findings, which may not apply to the general population.
However, while recurrent infections should be milder for most healthy people, he said it is important to consider changing risk factors for serious illness.
“Maybe there is someone who gained a lot of weight and became obese, or developed diabetes in the next time, or developed some other condition that put them at greater risk,” Adalja said. “Maybe they become immunocompromised; all of that will play an important factor.”
A study focused on American veterans, who are mostly older men, found that reinfections in this group appeared to have a higher risk of death or hospitalization. But several experts warned not to read too much of his early findings. (Ben Nelms / CBC)
In the elderly or in immunosuppressed individuals, medical professionals expect to see a number of poorer outcomes linked to severe reinfections, said Dr. Sameer Elsayed, a professor at Western University in London, Ontario, and a consultant in infectious, internal diseases. medicine and medical microbiology at the London Health Sciences Center and St. Joseph’s Health Care London.
This could include lung damage caused directly by the virus, he said, to issues such as worsening symptoms of “long COVID” from a previous infection or serious secondary infections by bacteria or fungi, especially in those people who require admission to a intensive care unit.
“The latter example is also similar to asthmatics who may require repeated hospitalizations for something that seems as simple as a common cold,” Elsayed said. “These repeated infections cause lung damage and can cause premature death depending on their severity, but we don’t see that with healthy people who continue to suffer from common colds year after year.”
Thus, as we all face the possibility of recurrent COVID-19 infections throughout our lives, your personal risk of serious illness could change over time, and the burden of reinfections for this constantly evolving virus does not. it will feel the same.