It’s an emotional decision to be anti vax.
No logic or facts you can present will change their minds.
Key life lesson: emotional positions cannot be changed by logic. Wish I’d known that years ago.
Except perhaps factual accounts of children of anti vaxers who became very sick, with for example whooping cough or measles.
Mostly we make decisions based on a gut instinct and then look for evidence to back that up, ignoring or down voting contrary evidence. In fact seeing opposing views can actually reinforce the original opinions.
Changing an opinion routed so deeply is rarely a single moment of revelation and move likely a slow, drop by drop erosion. So just be one of those drops.
You could read Street Epistemology's basics about how to begin discussing it: https://streetepistemology.com/publications/street_epistemol...