In a multicenter study of adults with symptoms of an infection of some type, 18.3% of COVID-19 survivors and 16.1% of COVID-negative participants reported persistent symptoms for at least 1 year, with some noting the emergence of new symptoms at 3 to 12 months.
The researchers from the University of California at San Francisco (UCSF) and the Centers for Disease Control and Prevention (CDC) who led the survey study said the findings show that long-COVID symptoms may overlap with those from other infections. The research was published late last week in Morbidity and Mortality Weekly Report.
From December 2020 to March 2023, the team analyzed data from the Innovative Support for Patients with SARS-CoV-2 Infections Registry (INSPIRE) from adults with symptoms of infection tested for COVID-19 who reported the presence or absence of symptoms every 3 months for 1 year at eight healthcare systems.
On each survey, participants recorded symptoms in eight categories: head, eyes, ears, nose, and throat (HEENT); constitutional; pulmonary; musculoskeletal; gastrointestinal; cardiovascular; cognitive; and extreme fatigue.
A total of 1,296 participants completed all surveys through 1 year, including 1,017 with positive COVID-19 tests and 279 who tested negative. About two thirds (67.4%) of participants were women, and 72.0% were White. A much greater proportion of COVID-19 patients had been hospitalized than those who tested negative (5.6% vs 0.4%).
Higher rate of fatigue in non-COVID patients at 1 year
Symptoms of an acute infection included fatigue, runny nose, headache, sore throat, shortness of breath, chest pain, diarrhea, forgetfulness, and difficulty thinking or concentrating.
From enrollment to 3 months, the prevalence of any symptom fell from 98.4% to 48.2% for test–positive participants and from 88.2% to 36.6% for those who tested negative. Symptom prevalence continued to decline through 1 year, affecting 18.3% and 16.1% of test-positive and test-negative participants at 1 year, a nonsignificant difference.
Symptom prevalence at baseline and persistence through 1 year varied by symptom category. At baseline, a higher percentage of COVID-positive participants reported symptoms in each category, except for extreme fatigue, than those who tested negative.
It shows that the burden after COVID may be high, but it might also be high for other non-COVID illnesses. We have a lot to learn about post-illness processes for COVID and other conditions.
The prevalence during the study period ranged from 0.3% for gastrointestinal symptoms to 5.9% for HEENT symptoms among COVID-positive participants and 1.1% for cardiovascular or pulmonary symptoms to 6.8% for extreme fatigue among those who tested negative. The only statistically significant difference at 1 year between the two groups was with extreme fatigue (3.5% positive vs 6.8% negative).
Symptoms not unique to COVID
Both COVID-positive and COVID-negative participants said symptoms in every category emerged or returned at 6, 9, and 12 months, but a greater proportion of test-negative participants reported emerging symptoms—except severe fatigue—at 6 and 12 months.
"Thus, these symptoms are not unique to COVID-19 or to post-COVID conditions," the study authors wrote. "Awareness that symptoms might persist for up to 12 months, and that many symptoms might emerge or reemerge in the year after COVID-like illness, can assist health care providers in understanding the clinical signs and symptoms associated with post–COVID-like conditions."
In a UCSF news release, lead author Juan Carlos Montoy, MD, PhD, said that previous research tended to focus on symptoms at only one or two points in time. "But we were able to describe symptom trajectory with greater clarity and nuance," he said. "It suggests that measurements at a single point in time could underestimate or mischaracterizes the true burden of disease."
The close similarity in symptom prevalence in the two study groups at 1 year was unexpected, Montoy said. "It shows that the burden after COVID may be high, but it might also be high for other non-COVID illnesses," he said. "We have a lot to learn about post-illness processes for COVID and other conditions."