A news report was out today on the main CNN homepage about measles cases in the U.S. being at the highest level in more than a decade.
If this had been a few days earlier I would have considered using it as a exam question: 'Rewrite this article as if you had some basic understanding of herd immunity.'
There will always be some fraction of the population that cannot be immunized. However if a sufficient proportion of the rest are vaccinated those who cannot be vaccinated (who probably have more serious problems to worry about) are protected. So, not getting children vaccinated is not just a (probably misguided) attempt by parents to reduce their child's overall risk - it is also a selfish act that should be labeled as such.
(Of course I'd probably feel totally different if I actually had children myself. But I don't. I have a dog though and he's vaccinated.)