Many people called anti vaxxers are fully vaccinated and have vaccinated their children. Some of these persons saw regression of skills happen with their children or auto immune issues, eczema, allergies, asthma etc. and decided to opt out of one or more vaccine or slow down/space out the vaccine schedule and they are called anti-vaxxers as well.
Its a phrase used to villify, to instill fear and to create the illusion usually in the media that anyone who does not comply with the vaccine schedule is against vaccines.
Most anti-vaxxers started out being very pro vaccines until their child was injured and then they weren’t.
-Submitted Urban Dictionary entry that was rejected by their editors that was submitted by a vaccine reform activist.