Basically none of which rises to the point of hospitalization and is gone in a few days.
The risk of hospitalization among even 18-29 year olds is not negligible. Neither is the risk of permanent side effects like diabetes. Those autoimmune conditions can and do strike even perfectly healthy individuals.
It is weird how the vaccine is probably 1000x safer than getting the virus, but young people in particular are happy with the idea that "that won't happen to me, I'm healthy and young" when it comes to the virus, while they're deeply concerned about vaccine side effects that really aren't concerning at all.
(And BTW "robust immune system" doesn't help you if your own immune system turns on you due to the virus).
