Mumps and the Midwest

My initial reaction to the Midwest Mumps outbreak story was "Hooray for being vaccinated!"  Then I read this:

Mumps, a viral infection, is usually not serious, and there have been no reports of deaths. The most troubling aspect of the epidemic is that many of the patients had been vaccinated. Does this mean that millions of people who thought they were safe actually are not?

So, uh, considering I live in Kansas, I'm feeling a bit worried...

And then the article goes on to suggest that there might be significance that many of the afflicted are young adults (read: college age), rather than children.  Crap.