But since getting sick with the coronavirus in March, Mr. Long, 54, has fallen into a distressing new cycle — one that so far has landed him in the hospital seven times.

Periodically since his initial five-day hospitalization, his lungs begin filling again; he starts coughing uncontrollably and runs a low fever. Roughly 18 days later, he spews up greenish-yellow fluid, signaling yet another bout of pneumonia.

Soon, his oxygen levels drop and his heart rate accelerates to compensate, sending him to a hospital near his home in Clarkston, Mich., for several days, sometimes in intensive care.

“This will never go away,” he said, describing his worst fear. “This will be my going-forward for the foreseeable future.”