My experience of observing folks being vaccinated is reactions are as varied as there are folks. Just the other day, one very mature lady emerged from the sports hall (The local leisure centre is being utilised), beaming that she felt fabulous, was thrilled to have been vaccinated and that she would not be having any reaction to it. If mind over matter can make things happen for her, she'll be perfect.
A while later, another lady emerged, having clearly not listened to what she was having (in terms of vaccine specific), to have a near melt-down on realisation (reading her card) that she had had the AZ vaccine. She declared it as totally rubbish, meaning it wouldn't work, she'd catch COVID and likely die. Her poor husband was shepherding her away, attempting to calm her down.
No I'm not suggesting either of those scenario were daft, or anything else, and I am not, in any way suggesting that Master Price was feigning his symptoms (tricky to feign a high temperature), but bottom line is until vaccinated nobody knows exactly how they will feel about the process, the variant given or any after effects. It seems to be quite an emotional process, even for those who don't expect it to be.
Interestingly, chatting with one of the medics who had been doing Care Homes for a while, they found that in many instances, the younger staff had more pronounces side-effect, post-vaccine, than the ladies and gents under their care, probably because their systems were well set to interrogate the vaccine.
This is one massive learning process for everyone.