Many people recover from the coronavirus on their own, with no complications. But new findings published in the American Thoracic Society’s American Journal of Respiratory and Critical Care Medicine suggest that the virus may persist in a person’s body even after symptoms disappear, according to a press release from the organization.

For the study, researchers collected throat swab samples from 16 patients with COVID-19 who were treated and released from the Treatment Center of PLA General Hospital in Beijing between January 28 and February 9. (The median age of patients was 35.5 years.)

Common symptoms among patients included fever, cough, sore throat and labored breathing.

Prior to discharging the patients, doctors confirmed each individual’s recovery using at least two consecutive polymerase chain reaction (PCR) tests that yielded a negative viral status. (PCR tests detect viral genetic material, according to Live Science.)

Findings showed that half of the patients treated for mild COVID-19 still had the coronavirus in their system for up to eight days after resolution of their symptoms. As a result, researchers advised doctors to treat asymptomatic patients and those recently recovered as carefully as symptomatic patients.

“If you had mild respiratory symptoms from COVID-19 and were staying at home so as not to infect people, extend your quarantine for another two weeks after recovery to ensure that you don’t infect other people,” said Lixin Xie, MD, a professor in the College of Pulmonary and Critical Care Medicine at Chinese PLA General Hospital, the study’s corresponding author.

Researchers stressed that the study was limited by the small number of patients and the fact that all had experienced milder infections and were recovered from COVID-19.

The scientists cautioned that results might be much different for more vulnerable patients, such as the elderly, the immunocompromised and those on immunosuppressive therapies (treatment that lowers the immune system’s activity).

In addition, researchers theorized that in those with more severe cases of infection, the virus might shed for even longer periods of time.

For more on the new coronavirus, click here, and click here for more on testing.