New research offers some hope for the many Americans living with long COVID.
People with mild cases typically see most of their symptoms subside within a year, according to a large-scale study conducted in Israel and published by the British Medical Journal. But some symptoms, like the loss of taste or smell, may persist longer.
The findings are in line with the observations of long COVID experts in the U.S.
"A lot of these patients will naturally get better over time," Dr. Ben Abramoff, director of the Post-Covid Assessment and Recovery Clinic at Penn Medicine, told NBC News. "One of the things we tell our patients is that sometimes the best medicine is time."
Scientists have been searching for answers on long COVID since the early months of the pandemic. The U.S. Centers for Disease Control and Prevention estimates that nearly 1 in 5 American adults who have had COVID-19 suffers from long COVID. The agency defines the condition as symptoms that persist for at least four weeks after an infection.
The list of symptoms associated with long COVID is lengthy, ranging from difficulty breathing, fatigue and a lingering cough to neurological issues like brain fog, depression and changes in smell or taste. It's not totally clear which people are at highest risk of developing long COVID, but some studies pinpoint those with severe COVID-19 illnesses or pre-existing health conditions, as well as unvaccinated people.
The latest study found the most common long COVID symptoms reported two months after infection were loss of taste and smell, breathing difficulties, cognitive challenges, fatigue and subsequent strep throat infections. Other symptoms tended to develop later: hair loss, chest pain, coughing, muscle aches and respiratory disorders.
The researchers found that vaccinated people who experience a breakthrough infection were less likely to develop breathing difficulties than unvaccinated people, but they had a similar risk to developing other long COVID symptoms. People ages 41 to 60 developed the more problems than other ages groups; though shortness of breath was a persistent issue among people over 60.
The children in the study experienced fewer long COVID symptoms than the adults.
"This is a reassuring large population medical record study," Michael Absoud, honorary reader in the Department of Women & Children's Health at King's College London, told STAT. "It confirms that in children, of the small proportion who have prolonged persistent symptoms post SARS-CoV-2 infection, the vast majority show a very good recovery."
The study analyzed the medical records of nearly 2 million people who were tested for COVID-19 in Israel before October 2021. The researchers compared the records of the nearly 300,000 people who tested positive to comparable patients who tested negative. The patients included in the study all had mild COVID-19 infections, defined as necessitating a doctor's visit, but not a hospitalization.
Though the study did not include long COVID cases caused by the omicron variant, doctors have reported that these patients also have been left with linger symptoms.
Abramoff and other long COVID experts urged caution when interpreting the study because it relied solely on medical records and not on feedback from patients themselves. Doctors' notes might not always include every symptom and it is difficult to gauge the severity of symptoms just from these notes, they said.
Though symptoms may be better within a year, it doesn't mean that they have been completely resolved. Some patients have had long COVID for two or more years. Other studies have suggested that brain fog and other neuropsychiatric conditions can persist for two years.
Penn Medicine and other health care systems in the Philadelphia area have opened post-COVID recovery clinics. Current treatment focuses on identifying achievable goals in recovery, depending on symptoms. Patients are often given physical or occupational therapy, mental health counseling and speech therapy.