He says the virus now hit him “like a hurricane.” He was weak and had trouble breathing. The hospital whisked him into the ICU, where nurses donned hazmat-style suits to enter his room.

They inserted a breathing tube, and put another tube down his throat for medicine to deal with pneumonia that developed in his lungs, he said.

Gagging and coughing, Mr. Thibault said he felt scared. His lungs would fill with saliva and nurses would dash in and clear them out, only to have to do it again two hours later.

“The feeling of choking. That was the worst part,” he said. “You feel like you’re asphyxiating, and you’re panicking because you can’t breathe.”

The agony went on for days.