A new research letter published Friday in the journal JAMA Network Open is shedding new light on the condition. Researchers from the University of Washington followed 177 people with laboratory-confirmed SARS-CoV-2 infection for up to nine months — the longest follow-up to date. Notably, this group included 150 outpatients, who had “mild” disease and were not hospitalized.

They found that 30% of respondents reported persistent symptoms. The most common were fatigue and loss of smell or taste. More than 30% of respondents reported worse quality of life compared to before getting sick. And 14 participants (8%) — including 9 people who had not been hospitalized — reported having trouble performing at least one usual activity, such as daily chores.

The researchers wrote that with 57.8 million cases worldwide, “even a small incidence of long-term debility could have enormous health and economic consequences.” There are now more than 110 million cases worldwide, according to the latest data compiled by Johns Hopkins University.