More than half of young adults with mild COVID-19 who self-isolated at home were still reporting troublesome after-effects six months later, a study from Norway published on Wednesday in Nature Medicine found.

The study included 312 COVID-19 survivors over age 16, with illnesses of varying severity. Overall, at six months, 189 patients, or 61%, reported persistent symptoms. Of the 61 patients between the ages of 16 and 30 who had only been mildly ill, 32 (52%) continued to have symptoms at six months, including loss of taste and smell (28%), fatigue (21%), trouble breathing (13%), impaired cognition (13%) and memory problems (11%).

The researchers said their patients' high rate of persistent fatigue "is striking" and appears higher than what is usually seen after other common viral infections, such as influenza, mononucleosis and dengue. "Considering the millions of young people infected during the ongoing pandemic," they conclude, the findings should prompt "population-wide mass vaccination" and other infection control measures. (https://go.nature.com/3xL7VFF)