I got an arm infection near the injection site of one vaccine that was so bad that there was briefly discussion of possibly needing to amputate it if the third round of antibiotics didn't clear it up. When the primary abscess at the injection site ruptured, I collected over a pint of bloodypusieyuck in the first couple of hours. Fortunately, it began resolving shortly thereafter, but it definitely made me more wary of vaccinations.

That being said, I still got vaccinated for COVID and some other things after that. Because I am capable of taking a deep breath, rationalizing the actual proven risk odds and then deal with my very real anxiety and do the thing I know has the highest chance of being the best course of action (at least sometimes).

Though, I do always ask they do it in my non-dominate arm now, just in case.