“We have seen many cases in which people take a long, long time to recover,” said Alessandro Venturi, the director of the San Matteo hospital in the Lombardy town of Pavia, adding that the discomfort often seems to last even longer for people with lighter symptoms. “It’s not the sickness that lasts for 60 days, it is the convalescence,” he said. “It’s a very long convalescence.”…

Studies also point to kidney, heart, liver and neurological damage, often from secondary infections, and no one knows what the long-term prospects are for those patients.

But even some of the infected who have avoided pneumonia describe a maddeningly persistent and unpredictable illness, with unexpected symptoms. Bones feel broken. The senses dull. Stomachs are constantly upset. There are good days and then bad days without apparent rhyme nor reason.

The afflicted find the simplest tasks taxing. Testing is still mostly reserved for the hospitalized, and so people suffering less severe but stubborn symptoms are trailed by doubt about whether they have the virus.