I've been vaccinated 3 times for MMR. Once as a kid, in my 20's when I worked for a hospital and if you were in a certain age group/vaccinated during certain years there was a possibility that the vaccine was ineffective. And again in my 30's when I was going to work for a hospital, again, and they titered me, only to discover that I didn't have an immunity. Got another round of shots. Wound up not staying with the hospital, or they would have titered me again. There'a a possibility that I still don't have an immunity. But considering I no longer work in emergency medicine, I'm not that worried.

Keep your feverish, rashy children to yourselves please.