CORONAVIRUS DISEASE 2019 (COVID-19) patients who experience even the mildest illness risk suffering symptoms for months, researchers in France found.

Two-thirds of patients who had a mild-to-moderate case of COVID-19 reported symptoms 60 days after falling ill, when more than a third still felt sick or in a worse condition than when their coronavirus infection began. Prolonged symptoms were more likely among patients aged 40 to 60 years and those who required hospitalization, according to staff at Tours University Hospital, who followed 150 non-critical patients from March to June.

Their study, published Monday in the journal Clinical Microbiology and Infection, adds to evidence that a proportion of the 35 million people known to have been infected with the SARS-CoV-2 virus worldwide will suffer lingering effects weeks to months later. Post–COVID clinics are opening in the pandemic’s wake to cater for an expanding population of so-called long-haulers — survivors left with scarred lungs, chronic heart damage, post-viral fatigue and other persistent, debilitating conditions.

“We were able to assess the evolution of the disease and demonstrate that even the mildest presentation was associated with medium-term symptoms requiring follow up,” Claudia Carvalho-Schneider and colleagues wrote. “Thus, the COVID-19 pandemic will involve a care burden long after its end.”

Two months after developing COVID-19 symptoms, 66% of adult patients reported suffering from at least one of 62 complaints, mainly a loss of smell and taste, shortness of breath, and fatigue, the researchers found. The study sought to identify the risk of longer symptom duration in patients with non-critical COVID-19, since much of the existing international research was based on survivors admitted to intensive care units, they said.

Longer-ranging studies and clinical trials will be critical to elucidate the durability and depth of health consequences attributable to COVID-19 and how these may compare with other serious illnesses, Carlos del Rio, executive associate dean at Emory University School of Medicine, and colleagues wrote in an editorial Monday in the Journal of the American Medical Association that reviewed the coronavirus’s persistent effects. —  Bloomberg