You (proverbial you) invade my health by walking about with measles. I think it's well within any group, even government, to mandate vaccinations that have been PROVEN to be effective. Privacy takes a back seat to health.
EDIT: And I love how this gets downvoted. Likely by people who vastly misunderstand mechanism of disease. Also likely the same people who show no courtesy to others when they are sick, and continue to frequent stores and social establishments, coughing and hacking with zero thought about it.