If you're a smoker with an O +/- blood type that is in relatively good health, it's no worse than a sore throat and sniffles, IE just a cold. However, hair shedding months after is a thing.

A/B bloodtypes, especially if you're indigenous or sicklecelled, you're fooked, it'll hit you hard.

Either way, if you got over it, don't get the stupid shot, it's designed to kill your ass.