Kelly LaDue thought she was done with COVID-19 in the fall of 2020 after being tormented by the virus for a miserable couple of weeks.
"And then I started with really bad heart-racing with any exertion. It was weird," says LaDue, 54, of Ontario, N.Y. "Walking up the stairs, I'd have to sit down and rest. And I was short of breath. I had to rest after everything I did."