here's my take on the MMR: i had a booster at 23, and promptly had grand mal seizures.
at the time, i was unaware that vaxes were more than just the virus (stupid, i know). now i know that the MMR has neomycin in it, and that is most likely what caused my reaction as i am allergic to almost all antibiotics.
so my advice to parents is always to at least check the ingredients and see if you have a history of reacting to anything in there. knowing to look for antibiotics helped me remove the IPV, MMR, and varivax from consideration. 3 fewer vaxes she COULD receive if i vax.