I'm on my local health agency's list to get my first dose this week. I've not seen it stated anywhere as a result of scientific observation, but just from others who had strong reaction symptoms with the Pfizer shot, and they thought the strong reaction was happening to people
because they had recovered from COVID prior to getting the vaccination. So that's just a possibility for why it happens; and KaileyT's experience happens not to contradict it.
I'm expecting I could be one of those people, too. Because although I've had great opportunity and success at keeping distance, and no occasion to need to get tested, just because of the way my immune system has worked in the past with other things, I suspect I'm probably one of "the asymptomatic carriers" for COVID, where I caught it and do not even notice.
So maybe getting the vaccine is going to finally make me pay a price for that
by giving me a strong reaction because of the COVID antibodies I had already developed.