I haven't gotten the flu since I was a kid (30+ years), I hardly ever get sick, unless I get the flu shot.
In 2000, I got the flu shot, sicker than a dog for a week right after.
In January of this year, I got a pertussis booster before going to Canada at the suggestion of my employer. The doctor talked me into a flu shot. 2 weeks later I slept in my hotel room for 36 hours straight with sweats/chills alternating about every hour. This is when I think I may have had CoVID.
Anecdotal, I know. My wife and children always get the shot, I am back to never again... I recommend it for everyone but myself.