COVID-19 patients are at least four times more likely to develop chronic fatigue than someone who has not had the virus, a new federal study published Wednesday suggests.

Researchers from the Centers for Disease Control and Prevention (CDC) looked at electronic health records from the University of Washington of more than 4,500 patients with confirmed COVID-19 between February 2020 and February 2021.

They were followed for a median of 11.4 months and their health data was compared with the data of more than 9,000 non-COVID-19 patients with similar characteristics.

Fatigue developed in 9% of the COVID patients, the team found. Among COVID-19 patients, the rate of new cases of fatigue was 10.2 per 100 person-years and the rate of new cases of chronic fatigue was 1.8 per 100 person-years.