One patient, Giuseppe Vavassori, 65, has developed short-term memory loss and now lives under a mountain of Post-it notes and handwritten reminders, with names and phone numbers, so he can still run his funeral home business. A post-covid MRI showed dot-like lesions on his brain.

Another, Guido Padoa, 61, recovered well enough that he was able to go on vacation this summer. But he sleeps four extra hours per night and sometimes falls asleep suddenly midday, head on the computer keyboard.

Some patients who were self-reliant before contracting the virus remain so weakened that, when they arrive for their follow-up appointments, they’re helped to the waiting room by relatives, or in wheelchairs. Four people so far were too frail to make it through the several hours of testing and were rushed instead to the emergency room. Other times, people show up months later, having been through the worst — oxygen support, intubations — and are, improbably, almost fine. Doctors say one of the virus’s mysteries is how recoveries can be swift for some and brutal for others.