I saw someone yesterday who was in his 30's with measles, his mother sitting next to him explaining why she didn't get him vaccinated because she thought it would make him sick.
It's unfortunate because there are many people who either can't be vaccinated due to allergies or have other legitimate medical issues such as being too young for the vaccine, that rely upon the herd immunity of the portion of the population that can be vaccinated. Opting out of vaccines puts these people at risk, not to mention the increased risk of child opted out.
There was a Frontline documentary (I think it was them) detailing this risk and it coming to a head in a smaller community where too many people were skipping vaccinations and the herd immunity was significantly diminished. It was a really interesting piece on what could happen if too many people start skipping vaccines.
Yes, it was Frontline. "The Vaccine War".
Even people who get the vaccines rely on herd immunity to some (stochastic) extent. My spouse got a complete vaccine set as a child but the Rubella vaccine didn't quite take; she only discovered that in adulthood while getting a routine pre-natal test. She's been vulnerable to Rubella her whole life without knowing it.