Vaccine anxiety advice?

My 8 year old son just got some annual vaccines today, but he worked himself up over how much it would hurt, to the point that he was scared, crying and jumpy before they even administered the first shot, and he had trouble sitting still through it. I tried using reason, saying that it’s only a pinch and it will be a little sore for awhile, but you’ll be fine just like you were last year, and we need vaccines to help keep our bodies healthy and prevent getting really sick. None of it seemed to help much. He even got a sticker and a sweet treat when we got home for good behavior and listening to the doctor and the MAs.

Does anyone have advice to help my son relax and stay calm when he’s getting vaccines? He was fine afterwards and I told him to give me a big bear hug and I told him he’s too strong and he’s squeezing me like a lemon. That made him giggle and dry his tears a little at least. For context I have ADHD and he has quite a few ADHD symptoms as well, but he doesn’t have significant behavioral problems, so he hasn’t been tested for it yet.