A new federal study identifies the 12 symptoms that most clearly characterize long-term COVID, but fails to explain why about 10% of individuals who experience even mild COVID-19 infection have health problems lasting months or can even last for years.
The National Institutes of Health RECOVER program analyzed nearly 10,000 participants and identified the 12 most commonly reported conditions of the approximately 200 previously recognized symptoms of long-term COVID. The 12 conditions range from brain fog and palpitations to sexual impotence and digestive disorders.
Despite these findings, scientists still don’t know what causes long-term COVID, why it only affects some people, or even how to treat and diagnose it.
The team behind the study said that while the research is inconclusive, it provides scientists with a “common language” to start working on treatments.
“Now that we can identify people with long-term COVID, we can begin more in-depth studies to understand the biological mechanisms involved,” study co-author Andrea Foulkes, a professor at Harvard Medical School, said in a press release. “One of the big conclusions from this study is the heterogeneity of long COVID: long COVID is not just one syndrome; it is a syndrome of syndromes.”
The 12 main symptoms identified in the study were:
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Loss of smell or taste
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Post-exertional malaise
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Chronic cough
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Brain fog
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Thirst
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Palpitations
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Chestpain
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Fatigue
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Dizziness
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Gastrointestinal problems
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Problems with sexual desire or ability
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Abnormal movements, such as tremors, unintentional movements, or stiffness
But those aren’t the only symptoms that define long-term COVID, the researchers said. Patients can have any of those symptoms, or many — or others not on the list — and suffer long-term consequences from the coronavirus.
“Sometimes I hear people say, ‘Oh, everybody’s a little tired,'” said Dr. Leora Horwitz, co-principal investigator for the RECOVER Clinical Science Core at NYU Langone Health, in the release. “No, there’s something different about people who have had COVID for a long time, and that’s important to know.”
The new research, published Thursday in the Journal of the American Medical Association, involved more than 8,600 adults who had COVID-19 at various stages of the pandemic, compared with 1,100 who were not infected.
The team identified 37 common symptoms that persisted after six months in COVID-19 patients compared to those not infected by the virus. Of that number, the 12 in the study were the most reported. About 20% of people who had COVID met the criteria after six months to suffer from long-term COVID – also known as Post-Acute Sequelae or SARS-CoV-2 infection or PASC.
“Americans living with COVID for a long time want to understand what is happening to their bodies,” said Dr. Rachel L. Levine, assistant secretary of health, in the release.
More than 100 million Americans are infected with SARS-CoV-2, the virus that causes COVID-19. The study found that persistent health problems were reported more frequently in individuals infected before the emergence of the omicron variant in December 2021. The rate of long-term COVID was also higher among the unvaccinated and those who experienced re-infection.
It is encouraging that the risk of long-term COVID appears to be declining. The most recent data from the US Census Bureau’s “Household Pulse Survey”, conducted via a monthly online questionnaire since April 2020, indicated that as of May 8, 10% of adults previously infected with COVID-19 had long-term COVID symptoms reported, up from 18.9% in June of the previous year.
According to the new research, this share drops to about 6% after six months.
“This study is an important step toward defining a long COVID beyond each individual symptom,” Horwitz said. “This approach – which may evolve over time – will serve as the basis for scientific discoveries and treatment designs.”
Reach Aidin Waziri: avaziri@sfchronicle.com