My young cousin, a healthy young man of about age 18, recovered fine from COVID, but then a few weeks later developed significant long term chest pains / heart problems he never had before, had to be hospitalized for that for over a week -- not hospitalized due to the flu symptoms themselves, but due to after-effects from it. He says it feels like a truck is parked on his chest, constant pain. His doctors are saying it is COVID related. They say he should be close to a full recovery within about 6 months or so, hope this is true.