The most important thing that the COVID vaccines do is prevent deaths and severe illness from COVID-19. The next most important thing they do is prevent many cases of milder illness—a job they’re not perfect at, but it’s still far better to be vaccinated than not. But what about long COVID, the still-mysterious long-term symptoms that can follow some coronavirus infections?
One of the reasons it’s hard to get a straight answer on this question is because long COVID itself is hard to define and has been hard to study. Symptoms of long COVID overlap with those of other conditions, including what used to be called chronic fatigue syndrome. It’s hard to study what you can’t define.
Chronic fatigue, now better known as myalgic encephalomyelitis, is also thought to be triggered by viral infections, at least some of the time. And if you have this condition or know anyone who does, you’ll be familiar with the frustrations that come with medical professionals being unsure of how to diagnose it and what treatments might work best. And this, in turn, is in part the result of the difficulty in studying it. It’s an endless cycle of “more research is needed.”
Fortunately, many researchers are taking long COVID seriously, but it will still be a while before we get solid answers to any of our questions about it, including how to prevent it.
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Logically, you can’t get long COVID unless you’ve had COVID. All of the COVID vaccines were authorized because they are effective at preventing serious COVID infections, so if you’ve been vaccinated, you’ve automatically lowered your chances of getting long COVID by lowering your chances of getting COVID at all.
The CDC agrees with this logic, stating on its page about long COVID that, “The best way to prevent post-COVID conditions [their name for long COVID] is by getting vaccinated against COVID-19 as soon as you can.”
Another area of current research is what happens when people get COVID despite being vaccinated. These cases, called breakthrough cases, are relatively uncommon, but they’re not unheard-of.
Breakthrough cases seem to be more mild than cases in unvaccinated people. Vaccinated people who get COVID are less likely have severe disease, to spend time in the hospital, or to die of their infection. A recent study by nonprofit Fair Health found that people with more severe symptoms are more likely to get long COVID than people with very mild symptoms.
Another recent study, published in the Lancet, found that people who were fully vaccinated were less likely to experience long-term symptoms. Specifically:
We found that the odds of having symptoms for 28 days or more after post-vaccination infection were approximately halved by having two vaccine doses. This result suggests that the risk of long COVID is reduced in individuals who have received double vaccination, when additionally considering the already documented reduced risk of infection overall.
I would never trust the results of a single study to tell us everything we need to know, since later studies could reveal more information that earlier ones missed. But so far, the evidence is pointing in the direction of vaccines reducing your chances of getting long COVID both by preventing COVID in general and possibly also by reducing the chances that regular COVID could progress to the l