The World Health Organization recently published an official definition for long COVID—when people don't fully recover from COVID and continue to suffer from various symptoms for weeks or months after they're once again negative—and a study now estimates how many long-haulers there actually may be. Nearly 240 million people worldwide have been diagnosed with COVID since the coronavirus started making its way around the globe, and scientists involved in the new research say more than half of those infected will have symptoms up to six months or longer after the initial illness, per a release.
For their study published Wednesday in the JAMA Network Open journal, researchers looked at nearly five dozen reports on data from about 250,000 unvaccinated adults and children who'd received a COVID diagnosis between December 2019 and March 2021. The scientists looked at the subjects' overall health one month after they'd "recovered" from COVID, as well as at two to five months, and then six months and beyond. Researchers found that more than half of the survivors at each of the intervals suffered from at least one lingering symptom, with the most common ones being mobility issues, pulmonary abnormalities, and mental health disorders.
Other longer-term symptoms included cardiovascular and digestive problems, skin conditions, and neurological issues, such as problems concentrating. "These findings confirm what many health care workers and COVID-19 survivors have been claiming— namely, that adverse health effects from COVID-19 can linger," says Penn State College of Medicine's Vernon Chinchilli, a study co-author, per the release. While the scientists say it's not clear why some people develop long COVID—and they concede COVID may not always be the cause, or the sole cause, of these later symptoms—theories circle around everything from reinfection, the virus causing immune systems to go haywire, or a boost in autoantibodies, which attack a person's own tissues or organs.
The researchers hope their findings can help in the creation of treatment and management plans for COVID patients to prevent health care systems from getting overwhelmed. They also advocate for getting vaxxed to avoid getting COVID, long or otherwise, in the first place. "Vaccination is our best ally to prevent getting sick from COVID-19 and to reduce the chance of long-COVID, even in the presence of a breakthrough infection," says study co-author Paddy Ssentongo. Recent research seems to back that up. (Read more long COVID stories.)