Several years ago when I was in college, there was a measles outbreak on the campus of a major university in my state. The cause was determined to be either a defective initial/booster vaccine, or those who were never vaccinated for it. There were some sick kids on that campus.
It was so bad, in fact, that the Department of Education issued an edict saying *every* college student in the state had to show proof of a booster vaccine or recent immunization in order to register for the next quarter! Even though I know I was vaccinated because I had to have been to start school, the health department didn't have a record of me getting the vaccine. So, I had to get a red measles shot. Hurt like the devil and my arm swelled up like a spider bite at the injection site. Still, it was preferable to getting the measles at 20.