By this point in the pandemic, you’ve likely had COVID-19 at least once. Maybe twice. Maybe even three times, as some unfortunate Canadians have experiencedas this virus evolves to become more adept at infecting us.
It is clear that re-infections with this coronavirus are the norm, much like those behind the common cold. Unfortunately, this also means that early speculation about one-off bouts of COVID-19 offering immunity against future infections is long gone.
What’s less clear is how often you can contract SARS-CoV-2, and whether future infections will always be milder than the first, as the virus finds its way into our bodies again and again.
Reassuringly, scientists say that for most healthy adults — including those with additional protection from vaccination — COVID-19 infections should become easier to deal with as your immune system gets retrained on how to deal with that particular one. pathogen.
Transmission electron micrograph of SARS-CoV-2 isolated from a patient. Scientists say the virus is capable of infecting people again and again. But how often can it happen and will it feel lighter each time? (National Institute of Allergy and Infectious Diseases)
“Your first infection with COVID will probably — not invariably, but probably — be the worst,” said infectious disease specialist Dr. Alison McGeer, a professor at the University of Toronto’s Dalla Lana School of Public Health.
“And then as you get more and more exposed to it, you get better and better protections.”
Coronaviruses strike repeatedly
After months or even years of completely avoiding the virus, you may be surprised that COVID-19 can strike you more than once.
At the start of the pandemic, some scientists expressed hopes for herd immunity—that if enough people contract or are vaccinated against COVID-19, herd immunity against infection will reach a threshold where the virus cannot find new human hosts.
Unfortunately, this is not easy with the coronavirus.
First identified in humans in the 1960s, viruses from this family have likely plagued us repeatedly for centuries. SARS-CoV-2 is the newest kid on the block.
“Four of these other family members cause about 30 percent of our common colds, and they reinfect us routinely,” said Dr. Amesh Adalya, a senior scientist at the Johns Hopkins Center for Health Security in Baltimore.
“We’ve all had multiple bouts of other coronavirus infections, and this virus has always targeted that. So re-infections are not something to be surprised by.”
However, they were rare during the early part of the pandemic. SARS-CoV-2 has been hitting people again and again at this point, for two and a half years, partly because we give it a chance.
“This would happen a lot more often if we weren’t all at home and keeping our distance,” McGeer said. “It’s not that the virus is doing anything different from what a virus would have done before; and that we behave differently.’
Scientists say reinfections were rare in the early years of the pandemic, in part because people largely stayed home, while more socializing now gives the virus a chance to spread. (Marc-André Turgeon/CBC/Radio-Canada)
Layer in increasingly infectious variants that are able to evade our immune system’s front-line soldiers, and you have a recipe for more regular reinfections. What is not clear is how often this virus will strike.
Four long-studied seasonal human coronaviruses appear to be able to re-infect humans every 12 months, according to research published in Nature Medicine which involved scientists following a group of healthy adults for more than 35 years.
But unlike this seasonal pattern, SARS-CoV-2 remains erratic — a constant roller coaster rather than one big spike and drop in a given year.
A seventh wave is now underway in Canada and many other countries, fueled by yet another immunity-evading Omicron subvariant, BA.5. This occurs during the summer months—well 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 not yet sure what path this virus will take in the long term.
“Are we likely to adjust to winter activity? Yes, eventually, but maybe not for another year or two,” she said. “Are we sure we will? No.”
Repeat infections are usually no worse than the first
What several experts who spoke to CBC News are more certain about is that subsequent COVID-19 infections should feel milder than the first. It’s not necessarily a walk in the park, but at least not as rough as your body’s first encounter with this virus.
“From all the literature I’ve seen, when re-infections happen with increasing frequency, they’re usually not worse,” said Angela Rasmussen, a virologist at 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 several ways to train your immune system to fight this virus faster and smarter. A person is directly exposed to SARS-CoV-2, which comes with all the potential health consequences of infection.
The other is to get vaccinated, which allows your body to learn about that particular pathogen without facing those risks. (Consider this option as a martial arts lesson instead of throwing it out in a surprise fistfight.)
Erin Wilson, a gym teacher and actor in Halifax, has contracted 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 she felt a little better the second time around. (Mark Crosby/CBC)
If you’re vaccinated and get COVID-19, the virus can still get past your immune system’s first line of defense — your neutralizing antibodies — and get into your cells, Rasmussen said.
“Immediately, your memory T cells from your vaccination will say, ‘Wow, I’ve seen this person before; it’s time to go out and start killing those cells that are infected with it,” she explained.
In other words, a well-trained immune system cannot prevent infection, but it can often quickly control it. This means that an invader that once might have wreaked havoc just doesn’t have that chance.
So far, that’s been the experience of Erin Wilson, a gym teacher and actor in Halifax who recently contracted COVID-19 again after contracting it for the first time last December. (She is also vaccinated.)
The first round left her exhausted and in bed for days, “totally incapacitated.” Her next bout wasn’t pleasant—a few days later she was still struggling with chest congestion, coughing, and fatigue—but she noticed it was a little easier.
“It didn’t knock me out as much the second time,” Wilson said.
Not every reinfection will be “benign”
So if you’ve already been through COVID-19 at least once before, should you throw caution to the wind and catch it again and again? Not exactly.
The virus doesn’t treat everyone the same, Johns Hopkins’ Adalya stressed. “What we’re learning is that not every second infection or third infection is going to be benign — and that’s going to be especially true when you’re dealing with higher-risk populations.”
One study focused on American veterans — who were mostly older men — found that re-infections in this group appeared to come with a higher risk of death or hospitalization.
The paper, which has not yet been peer-reviewed, has made headlines in recent weeks. But several experts, including Adalya, cautioned against reading too much into the early findings, which may not apply to the general population.
However, while re-infections should feel milder for most healthy individuals, he said it’s important to keep in mind the changing risk factors for severe disease.
“Maybe there’s someone who gained a lot of weight and became obese, or developed diabetes later on, or developed some other condition that puts them at higher risk,” Adalya said. “Maybe they become immunocompromised — all of that will play a factor.”
One study focusing on US veterans — who are mostly older men — found that re-infections in this group appeared to come with a higher risk of death or hospitalization. But several experts cautioned against reading too much into the early findings. (Ben Nelms/CBC)
In the elderly or in people who are immunosuppressed, health professionals expect to see a range of worse outcomes associated with severe reinfections, said Dr. Samir Elsayed, a professor at Western University in London, Ontario, and a consultant in infectious diseases. , internal medicine and medical microbiology at the London Health Sciences Center and St. Joseph’s Health Care London.
This can include lung damage directly caused by the virus, he said, to problems such as worsening symptoms of “prolonged COVID” from a previous infection or serious secondary infections from bacteria or fungi — especially in those individuals who need intensive care unit admission.
“The latter example is also similar to asthmatics who may need multiple hospitalizations for what appears to be as simple as a common cold,” Elsayed said. “These recurrent infections cause lung damage and can potentially lead to premature death depending on their severity, but we don’t see this in otherwise healthy people who keep getting common colds year after year.”
So, because we all face the possibility of re-infections with COVID-19 throughout our lives, your personal risk of serious illness may change over time — and the burden of re-infections from this ever-evolving virus will not be felt equally.
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