Allergic reactions to vaccines of any type are somewhat normal, if rare. Usually those don't relate to the vaccination agent itself but accompanying chemicals that trigger your immune system (after all, the immune system won't launch an attack if you got stabbed with a needle) to go into attack mode. When you have an allergy to vaccines, this attack mode goes into overdrive and causes a widespread release of cytokines and other immune system agents. In some cases the reaction can be driven by the vaccination agent itself but from what I recall that is exceedingly rare.