That could work
- no insurance coverage for treatment if you are not vaccinated
Insurance companies would love that, but I'm pretty sure it would violate the ACA
- fines for not vaccinating your children
That leaves stupidity as the only reason not to get vaccinated./p>
Stupidity, ignorance, religious preference (which I know a lot of people 'round these parts will lump in with stupidity), lack of access, distrust of the government, distrust of doctors, etc.
Just because you can only think of one reason doesn't mean it's the only reason.
there should be child abuse laws for not giving your child required medical care that kick in.
Look, bud, if you don't like living in a country that promotes and supports individual liberty, you're free to either try and amend the Constitution or expatriate. But don't be a self-righteous, dickhead fundamentalist who demands laws be passed to support your opinion by taking rights and freedoms away from other people. 'Cuz that's fucked.
You could also reverse it, i.e. a tax deduction for vaccination, in case the psychology works better that way.
That's your best bet - provides the right incentive, and is Constitutionally sound. The flat-taxers won't like it, but since when does anyone care what a flat-taxer thinks?