LOS ANGELES, July 20 (Xinhua) -- A new study of U.S. researchers has found that nearly one in four COVID-19 sufferers had long COVID, symptoms that last 12 weeks or longer.

The study, led by researchers of the University of Southern California (USC), recruited about 8,000 respondents from across the country to answer biweekly questions about their overall health and COVID-19 status from March 2020 to March 2021.

After accounting for preexisting symptoms, about 23 percent of the participants reported that they had experienced new-onset symptoms during infection which lasted for more than 12 weeks, according to the study, published in Scientific Reports.

In addition, the researchers found that people had significantly higher odds of experiencing long COVID if they were obese, experienced hair loss, experienced headache, or experienced a sore throat, at the time of infection.

"Long COVID is a major public health concern. Twenty-three percent is a very high prevalence, and it may translate to millions of people," said first author Qiao Wu, a doctoral candidate at the USC Leonard Davis School of Gerontology.

"More knowledge on its prevalence, persistent symptoms and risk factors may help health care professionals allocate resources and services to help long haulers get back to normal lives," Wu said.