Liability of an anti-vaxer

Factual Questions
1

I am assuming that while someone is legally allowed to not vaccinate their kid, they are still liable for that choice. Suppose someone is not vaccinated and comes down with an illness like pertussis, measles, mumps, etc. They then infect someone who was vaccinated but for whatever reason the vaccination did not protect him- either it was ineffective or wore off before the booster or something. OR infected a little baby that was not old enough for the vaccine. What sort of criminal or civil liability would the anti-vax parent face if any?

2

I imagine it would be very difficult to prove beyond reasonable doubt, that the source of the infection was a particular unvaccinated child. After all - the unvaccinated child had to have been infected by someone else.

3

In that case the anti-vax parent would be vindicated. The vaccinated child has received an invasive medical procedure, one that is not risk-free but has been benefit-free.
Interesting that your response in that case would be to sue another parent and not the maker of the faulty vaccine.

4

The OP also cited transmission of infection to a young child not yet eligible for vaccination.

Also, no medical procedure/prophylaxis is 100% effective; vaccines may not “take” in certain individuals (possibly due to an immune problem) which has nothing to do with the vaccine being “faulty”. Individuals who disrupt herd immunity by going unvaccinated are arguably at fault if they cause disease outbreaks (again, hard but potentially not impossible to prove, especially with modern molecular techniques).

I don’t know of any cases where someone has successfully (or for that matter, unsuccessfully) sued another person for harm due to lack of vaccination. That strikes me as a difficult civil case. What I would like to see is a test case where an antivax figure or organization targets a specific population with falsehoods about immunization, a dangerous vaccine-preventable disease breaks out and those harmed sue the propagandizer(s) as a result.

Discussions of liability for failure to vaccinate have a way of bringing out the best in everyone.