Non-vaccinators should pay an annual penalty. This issue should be treated the same way healthcare coverage is treated. When individuals choose not to buy healthcare coverage, the odds increase that the public will have to pick up the tab for any healthcare costs they incur (e.g. ER visits) which are usually much higher than if they had preventative care. (This accountability principle was upheld by the right-leaning SCOTUS, so let's not devolve this vox into a conversation about Obamacare.) Along those lines, parents who opt-out of child vaccination would be required to pay a hefty annual penalty approximately equal to the healthcare costs they place on the public. It's only fair and responsible.