Fl vaccine, worst side effect (GBS) has a rate of less than 1 in 500,000 (<0.0002%)source
How about rabies vaccine... if you need to get it then by not getting it you have a 100% chance of death (rabies is 100% fatal in humans) and the worst side effect (also GBS) has happened so rarely that there is nothing actually linking it to the vaccine, we are talking about a handful of cases ever (less than 20 cases from more than millions of doses given) source
So I will take a sore arm and potentially some hives from the boosters over guranteed death.
We now know that only 1% of vaccine adverse reactions are being reported so we cannot go by the official figures. I personally know someone who got GBS from a vaccines so would also doubt the official figures..