I used to agree but a few of my 20-29 year old friends have had much worse experiences than expected. One had some neurological side effects, which is rare but happens, that affected his eye movement and made it impossible for him to read or work comfortably.

It wasn't healing and it turned out he had an undetected issue processing folic acid I believe, which has an effect on how your body heals from neurological damage. He's recovering now after 3 months but has to take folic acid and other supplements 5 times a day.

Other friends have had persistent diminished lung capacity for months on end; these are folks who had no co-morbidities and in their 20s.