I'm probably gonna get called an antivaxxer again (getting my booster next week) but I do have some questions about how these reports of side effects are actually collected... this is pretty much anecdotal but myself and almost all of my colleagues had some kind of side effect (mostly sore arm + mild-moderate flu like symptoms) but everyone just kind of accepted it and went about their business, nobody really thought about reporting these effects as they were already more or less predicted. There is a (VAERS-like) system for reporting side effects in place here in The Netherlands, but if nobody reports feeling under the weather for a day or two, the appearance may be that there are far fewer cases of mild-moderate side effects than is actually the case.
In Finland we also have a website where you can report side effects, but yeah, there really isn't any push or directions from any officials to report the side effects.
Along with having a sore arm for three days I got irregular heartbeats for a bit over one week and couldn't raise my left leg for the next day, but I only bothered to fill up the side effect form like 3-4 weeks after the shot as me being a lazy bastard just thought "nah, maybe later, maybe never".
This was from the first Pfizer shot. Haven't had the second shot yet.
I imagine there are lots of people who just can't be bothered to report anything.
And also I'm sure some don't want to report anything for some sort of denial reasons. Like, when I took the shot, there was this young woman, maybe 18-20, or a bit younger, who really was struggling against passing out because his father* was there claiming that there has been no problems with the vaccines for young people and told her to disregard whatever was happening. She was really struggling and even told she's losing her vision. Gladly a doctor/nurse eventually noticed it and she got help. I almost interfered too because it was so clear that she's about to faint soon. When we got the shot and had to wait for 15 minutes before leaving we were told we should raise our hand if we feel anything weird in our bodies, but there she was, fighting back while his father trying to psyche her to dismiss her problems. It's either that he didn't want to admit something can happen after taking the shot or didn't want her daughter to look weak, or both. Anyway, I wouldn't be surprised if people like that father there wouldn't want to report any side effects.
*I assume it was her father because of the age difference