Christopher Labos: How to reduce the risk of contracting prolonged COVID

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There is still much that is uncertain about the lingering symptoms we have come to call prolonged COVID. It is still not clear why it happens, how common it is, and how to treat it. but a investigation letterr recently published in the Journal of the American Medical Association provides at least some advice on how we can prevent it.

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Until now, there was ambiguity about whether or not vaccination prevented prolonged COVID. Data from the US Department veterans affairs suggested that persistent symptoms were lower in vaccinated people, but not all of the early data were completely consistent. Part of the problem with studying prolonged COVID is that different groups use different definitions. the US Centers for Disease Control and Prevention. defines it as symptoms that persist for four weeks after infection whereas, the World Health Organization used three months after the start of the COVID infection. Depending on which definition you use, you can get very different estimates of the actual duration of COVID. The risk of prolonged COVID will also differ depending on whether you consider people who were hospitalized for severe infections, people with mild infections, or a combination of the two. When different studies use different methodologies, comparing them becomes an apples to oranges problem.

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The most recent data, from researchers in Milan, provides useful information. The researchers looked at healthcare workers at nine medical centers in Italy and compared the COVID recovery of vaccinated and unvaccinated employees. Workers were being tested for COVID every one to two weeks, so virtually all cases would have been detected. If mild cases went undiagnosed, that would provide a falsely elevated estimate of the risk of prolonged COVID. The researchers also limited their analysis to non-hospitalized COVID patients, again guarding against overestimating the risk of prolonged COVID by mixing milder and more severe cases.

Perhaps unsurprisingly, older patients and those with underlying medical conditions were more likely to have persistent symptoms a month after infection. That said, I have anecdotally seen many younger patients with persistent symptoms, and it is important to remember that lower risk does not mean zero risk.

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Interestingly, the risk of prolonged COVID did not differ significantly by wave, which runs counter to the idea that newer variants are less likely to cause severe illness. What made the biggest difference was vaccination status. Getting two or three doses lowered the odds of developing prolonged COVID by 75 percent and 85 percent, respectively. Receiving a single dose did not. Since the data was largely derived from infections that occurred in 2021, many health care workers had only received two doses at that time.

Intuitively, it seems logical that vaccination would reduce the risk of prolonged COVID, and many of us assumed that would be the case. Vaccination reduces the severity of the disease and also prevents infection. Despite what people say online, multiple studies have shown that vaccination with three doses plays an important role in preventing infections. While the vaccines are less protective against Omicron than the Delta variant, three doses still reduced the chance of infection by 76 percent.

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Many aspects of prolonged COVID still defy simple answers. There is no clear diagnostic test or treatment; people have very different symptoms that may not all be due to the same cause. Symptoms improve over time, but it’s hard to predict who will get better and how long it will take. The only thing we can say with a little more certainty is that vaccination appears to reduce the risk of persistent symptoms. Of course, the best way to avoid prolonged COVID is to not get it in the first place, and vaccinations can help with that, too. You can also make him wear a mask and be careful.

Christopher Labos is a Montreal physician and co-host of the Body of Evidence podcast.