It is clear that reinfections from this coronavirus are the norm, as are those behind the common cold. Unfortunately, this also means that early speculation about single bouts of COVID-19 conferring immunity against future infections is long gone. What’s murkier is how often you can get infected with 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 treat as your immune system gets retrained 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 re-infecting people again and again. But how often can it happen and will it feel milder each time? (National Institute of Allergy and Infectious Diseases) “Your first infection with COVID is probably — not always, but probably — the worst,” said infectious disease expert Dr. Allison McGeer, 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 avoiding the virus altogether, it may come as a surprise that COVID-19 can strike you more than once. Early in the pandemic, some scientists raised hopes around herd immunity — that if enough people caught COVID-19 or were vaccinated against it, collective immunity to the infection would reach a threshold where the virus couldn’t find new ones. human hosts. Unfortunately, this is not easy with a coronavirus. Viruses in this family, first identified in humans in the 1960s, 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 re-infect us regularly,” said Dr. Amesh Adalja, a senior researcher at the Johns Hopkins Center for Health Security in Baltimore. “We’ve all had many bouts of other coronavirus infections, and that’s where this virus has always gone. So reinfections shouldn’t be surprising.” They were rare, however, throughout the early part of the pandemic. SARS-CoV-2 is hitting people again and again at this point, two and a half years later, in part because we give it a chance. “This would happen a lot more often if we weren’t all staying home and keeping our distance,” McGeer said. “It’s not that the virus is doing anything different than it would have done before, but that we’re behaving differently.” Scientists say reinfections were rare in the early years of the pandemic, in part because people largely stayed at home, while more socializing now gives the virus a chance to spread. (Marc-André Turgeon/CBC/Radio-Canada) Throw in increasingly infectious variants that are capable of evading our immune system’s front-line soldiers, and you have a recipe for reinfections on a more regular basis. What is unclear is how often this virus will strike. Four long-studied seasonal human coronaviruses appear capable of re-infecting 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 — more like a steady rollercoaster than a big ebb and flow in any given year. In Canada and many other countries, a seventh wave is now underway, fueled by another sub-variant of Omicron, BA.5, which suppresses the immune system. It occurs in the summer months – well before the typical cold and flu season – and not long after previous waves caused 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. “Will we possibly settle into winter activity? Yes, eventually, but maybe not for another year or two,” he said. “Are you sure we’re going? No.”
Reinfections are usually no worse than the first
What several experts who spoke to CBC News are most certain of is that the next few COVID-19 infections should feel milder than the first. This isn’t 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 reinfections happen with increasing frequency, they’re usually not worse,” said Angela Rasmussen, a virologist at the University of Saskatchewan’s Vaccine and Infectious Diseases Agency in Saskatoon. “And that’s exactly what you’d expect, because that’s how the immune system works.” There are a few ways to train your immune system to fight this virus faster and smarter. One is directly exposed to SARS-CoV-2, which comes with all the possible health consequences of an infection. The other is to get vaccinated, allowing your body to learn about that particular pathogen without facing those risks. (Think of this option as a martial arts lesson, rather than throwing it into a surprise fistfight.) Erin Wilson, a gym teacher and actress in Halifax, has contracted COVID-19 twice — the first time last December and again in July. Both times the virus hit her hard, leading to fatigue, coughing and chest congestion, but she says it felt a little easier the second time around. (Mark Crosby/CBC) If you’ve been vaccinated and get COVID-19, the virus can 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 are going to say, ‘Wow, I’ve seen this guy before; it’s time to go out and start killing these cells that are infected with this,’” he explained. In other words, a well-trained immune system cannot prevent infection, but it can often control it quickly. This means that an attacker who might once have wreaked havoc simply doesn’t get that chance. So far, that’s been the experience for Erin Wilson, a gym teacher and actor in Halifax, who recently contracted COVID-19 again after first contracting it 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—and for several days afterward, she was battling chest congestion, a cough, and fatigue—but she noticed it was a little easier. “The second time it didn’t knock me out as much,” Wilson said.
Not all reinfection will be “benign”.
So, if you’ve already gotten over COVID-19 at least once before, should you throw caution to the wind and catch it again and again? Not exactly. The virus does not treat everyone equally, said Adalja, of Johns Hopkins. “What we’re learning is that not every second or third infection is going to be benign — and that’s especially true when you’re dealing with higher-risk populations.” A study focusing on US veterans — who are mostly older men — found that reinfections in this group appeared to be accompanied by a higher risk of death or hospitalization. The paper, which is not yet peer-reviewed, has made headlines in recent weeks. However, several experts, including Adalja, cautioned against reading too much into his early findings, which may not apply to the general population. But while recurrent infections should feel milder for most healthy people, 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 in the next year or developed some other condition that puts them at higher risk,” Adalja said. “Maybe they become immunocompromised – all of that will play a factor.” A study that focused on US veterans – who are mostly older men – found that reinfections in this group appeared to be accompanied by a higher risk of death or hospitalization. However, several experts cautioned against reading too much into his early findings. (Ben Nelms/CBC) In the elderly or those who are immunocompromised, medical professionals expect to see a range of worse outcomes associated with serious reinfections, said Dr. Sameer Elsayed, a professor at Western University in London, Ont., 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 could include lung damage caused directly by the virus, he said, to issues such as worsening of “long-lasting COVID” symptoms from a previous infection or serious secondary bacterial or fungal infections — particularly in those people who need to be admitted to Intensive Care Unit. “This last example is also similar to asthmatics who may need repeated hospitalizations for something seemingly as simple as a common cold,” Elsayed said. “These repeated infections cause lung damage and may lead to early death depending on their severity, but we don’t see that with otherwise healthy people who keep getting colds year after year.” So, as we all face the possibility of repeated COVID-19 infections in our lifetimes, your personal risk of serious illness could change over time — and the burden of re-infections from this ever-evolving virus won’t be as felt .
