A recent study funded by the National Institutes of Health has identified symptoms that are the most distinctive to long COVID, which should eventually allow researchers to treat the symptoms that can devastate people's lives for months or years after a COVID-19 infection. The symptoms include fatigue, especially after exercise, brain fog, dizziness, gastrointestinal symptoms, heart palpitations, issues with sexual desire or capacity, loss of smell or taste, thirst, chronic cough, chest pain, and abnormal movements. Each self-reported symptom is given a score and someone with a score of 12 or more “is a person who very likely has long COVID,” according to Dr. Leora Horwitz. More than 20% of people who've had COVID score high enough six months after their infection to meet this working definition of long COVID, although one-third of them no longer meet the criteria at nine months.
It's not yet clear from this study whether people with long COVID can be classified into different groups according to their symptoms, Horwitz said, though other research has tried to do that. Long COVID has a long potential list of causes, including tiny blood clots affecting organ function, lingering virus or viral particles, and dysautonomia, where activities that happen without thought, like maintaining heart rate and blood pressure, are thrown out of whack.
More than 20% of people who've had COVID score high enough six months after their infection to meet this working definition of long COVID, although one-third of them no longer meet the criteria at nine months. Reinfection and severity of infection were also linked to a higher incidence of long COVID, according to the study. Vaccination clearly reduces the risk for long COVID, said Horwitz.
The survey of nearly 10,000 Americans found long COVID is more common among people infected before the emergence of the omicron variant in late 2021 and among those who had not been vaccinated. Researchers now plan to connect the survey responses with biological data, such as blood samples and scans, to delve into the causes of these symptoms. Although the process seems slow, it is essential to precisely define long COVID before researchers can pursue treatments, said Andrea Foulkes, the study's other lead author. If they don't have a way to distinguish people with long COVID from those without, they won't be able to tell if a treatment is making a difference.