Long COVID can persist for at least a year after the acute illness has passed, or appear months later, according to the most comprehensive look yet at how symptoms play out over a year.
The multicenter study, a collaboration between UC San Francisco, the Centers for Disease Control and Prevention (CDC) and seven other sites, expands knowledge of post-COVID-19 conditions, describing trends in more detail than previous research and highlighting significant impacts the epidemic has had on the U.S. health care system.
The study appears Aug. 10, 2023, in Morbidity and Mortality Weekly Report (MMWR), a publication of the CDC.
For about 16% of the COVID-positive people in the study, symptoms lasted for at least a year; but for others, they came and went. The study assessed symptoms every three months, enabling researchers to differentiate between symptoms that improve and those that emerge months after the initial infection.
“It was common for symptoms to resolve then re-emerge months later,” said lead author Juan Carlos Montoy, MD, PhD, an associate professor within UCSF’s Department of Emergency Medicine. “A lot of prior research has focused on symptoms at one or two points in time, but we were able to describe symptom trajectory with greater clarity and nuance. It suggests that measurements at a single point in time could underestimate or mischaracterizes the true burden of disease.”