Depending on the state you live in, you can provide a letter, request a form etc stating that you have chosen not to vaccinate your child. I believe that one of the "outs" is to say that it is on religious grounds ie: against your religion. I have a family member that sends her daughter to a private school and she just has to file a statement with them each year. We have decided to home school our kids (for many reasons, we would do this even if vaccinations weren't an issue) so that could be an option for you too. You should definitely check out this site too: