anti-vaxxer
noun /ˌænti ˈvæksə(r)/
/ˌænti ˈvæksər/, /ˌæntaɪ ˈvæksər/
(informal)- a person who is opposed to vaccination, especially a parent who does not wish to vaccinate their child because they believe it could be harmful
- The outbreak of measles has been blamed on anti-vaxxers who refuse to vaccinate their kids.