Has the risk of getting long covid been overestimated?
Long covid, the experience of lingering symptoms after a covid-19 infection, remains a poorly understood condition, and researchers disagree on how common it is
By Clare Wilson
27 September 2023
Some people continue to experience symptoms long after a covid-19 infection
Jikaboom/iStockphoto/Getty Images
If you are infected with the coronavirus, how likely are you to develop long covid? It is an important question, as the answer could affect individuals’ decisions about taking precautions against the virus, such as whether to wear a mask, and decisions by medical bodies, such as who should be offered booster vaccines.
Unfortunately, our scientific understanding of the condition has remained poor throughout the pandemic. Long covid is generally used as an umbrella term for any kind of lasting symptoms after covid-19 infection, usually ones that have gone on for three months or more. The most common include fatigue, breathlessness and difficulties concentrating, but some doctors say it encompasses over 200 different symptoms.
Now, Tracy Beth Høeg at the University of California, San Francisco, and her colleagues have claimed that the likelihood of this condition has been overestimated. While some studies suggest long covid affects as many as half of all those infected, that is down to their loose definitions of the condition or poor design. The most authoritative studies suggest that only a few per cent of people are affected, says Høeg.
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But critics of this analysis say the researchers have ignored other well-designed studies that support the idea that the virus often has lasting effects. Why is figuring out how common it is to get long covid so difficult?
Part of the problem is we don’t know exactly what causes the condition. Several explanations have been proposed, including that the virus persists in the body or that it causes either immune system overactivity or underactivity – but it is unknown which of these, if any, are correct. Long covid also seems to have similarities with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), another mysterious syndrome of persistent tiredness that may arise after other infections.
