Epidemiology: Long COVID in individuals with mild illness assessed

More than half of home-isolated young adults (aged 16–30 years) with mild COVID-19 experienced persistent breathing trouble, loss of taste and smell, fatigue or impaired concentration and memory 6 months after their initial infection in a study of 312 patients in Bergen, Norway, published in Nature Medicine.

Long-term complications following COVID-19 are common in hospitalised patients with severe symptoms, but the burden of so-called ‘long COVID’ in mild to moderately ill patients is not well understood.

To assess the long-term symptoms of individuals with mild COVID, Bjørn Blomberg and colleagues followed up with a group of 312 patients, who made up 82% of the total cases in Bergen during the first pandemic wave in Norway. This group comprised 247 home-isolated and 65 hospitalised individuals with a median age of 46 years, 51% of whom were women. Participants went to a clinic on a bimonthly basis to have their symptoms recorded by interview with a physician. At 6 months, 61% of all patients had persistent symptoms, which were independently associated with the severity of the initial illness. A total of 61 (52%) of home-isolated young adults continued to have symptoms at 6 months, including loss of taste and smell (28%), fatigue (21%), trouble breathing (13%) and impaired cognition (13%) and memory problems (11%).

The authors express their concern that some non-hospitalised young people suffer from potentially severe symptoms for as long as half a year after infection, and note that the high occurrence of persistent fatigue in COVID-19 patients is striking and appears to be higher than that observed after other common infections, such as influenza and Epstein–Barr virus mononucleosis. Considering the millions of young people infected during the ongoing pandemic, the authors argue for comprehensive infection control, population-wide mass vaccination and further investigation into the spectrum of symptoms in milder cases.