Symptoms caused by the coronavirus disease 2019 (Covid-19) such as fatigue, trouble breathing and muscle aches persist up to nine months after infection, even in young, healthy people who experience mild illness, a study published Friday by JAMA Network Open found.

Fatigue and loss of sense of taste or smell were the most common persistent symptoms, as each were experienced by 14 percent of patients assessed three to nine months after they first reported symptoms, the data showed.

In addition, roughly 5 percent of patients reported persistent headaches, breathing difficulties or muscle and body aches.

Nearly 14 percent of patients in the study reported three or more persistent symptoms during follow-up visits, according to the researchers.

Although patients who required hospital care for Covid-19 were slightly more likely to report persistent symptoms, those who experienced mild illness did as well, the researchers said.

“Even in relatively young, healthy individuals — and even in those who have a mild case of Covid-19 – symptoms can last for months after infection,” study co-author Dr. Denise J. McCulloch said.

These symptoms “can adversely impact quality of life,” said McCulloch, an infectious disease specialist at the University of Washington in Seattle.

EARLIER STUDIES

Earlier studies have found that up to 75 percent of people infected with the coronavirus experience long-lasting symptoms, with fatigue and weakness being the most common.

These findings highlight that while Covid-19 can cause serious illness in some people, it can also have milder, but enduring effects on others, McCulloch said.

For this study, she and her colleagues evaluated 177 adults who had recovered from the virus after being treated at their clinic between August and November.

Of these study participants, 16 required hospital care for Covid-19, while 161 were either treated as outpatients or were asymptomatic throughout, the researchers said.

Although two-thirds of the patients were symptom-free three to nine months after infection, 16 percent reported one or two persistent symptoms and 14 percent reported three or more, the data showed.

Persistent fatigue and loss of sense of smell were most common, but muscle and body aches, fever, breathing problems, cough, sore throat, diarrhea, sweats and chills were also reported, according to the researchers.

More than 30 percent of the patients in the study said the lingering effects of Covid-19 were still impacting their quality of life months after infection, the researchers said.

In addition, 8 percent of the study participants indicated that their persistent symptoms affected at least one of their daily activities.

Study participants will be monitored for the next two years to track their long-term health, the researchers said.

“Because Covid-19 has only been around for a year, the long-term health consequences are not yet known,” McCulloch said. “However, the fact that people are still experiencing symptoms … months after their illness is definitely concerning.”