I don’t know if it’s been mentioned, but I’d say the abortion debate answers this question. We’ve established that medical decisions are between patients and their doctors and the government has no right to intervene. Nor can the government force people to undergo medical procedures. If you can’t force people to undergo ultrasounds, you can’t force people to have needles stuck in them.
Plus, people do die from vaccines. The risk is tiny, but in a large population, some do die, and making people buy that particular lottery ticket is not justifiable.
I think the anti-vax crowd has done the country a lot of harm, but we’re talking basic rights here.