For me it’s not the needle. I have no trouble with vaccinations. But as soon as I lose blood in a medical way (losing blood from injuries isn’t a problem), no matter how little, I get flop sweat and start to get nauseous. The problem is purely psychological and talking to the nurse absolutely helps. I have to lie down though. I’m fairly sure it comes from a traumatic experience when I was a kid. An inexperienced nurse had to poke the needle into my arm several times and had to fill many tubes for whatever reason. She then sent me to the waiting room and didn’t apply any pressure to the plaster. So I sat in the waiting room and blood just ran down my arm like there’s no tomorrow. I almost passed out.