COVID’s aftereffects may reverberate for more than three years, often causing lingering pulmonary and gastrointestinal symptoms, according to a large study of US veterans.

Although the risks for heart attack, blood clots, muscle weakness and a slew of other health problems abate over time, many patients remain in worse shape, especially those who’ve been hospitalized, researchers at the Washington University School of Medicine in St. Louis and the Veterans Affairs St. Louis Health Care system said.

“We are used to thinking about infections as acute events with health effects that manifest around the time of infection,” epidemiologist Ziyad al-Aly, the study’s senior author, said in an email. “The data shows that COVID can cause health effects even three years later.”