Definition of anti-vaxxer in English:
 anti-vaxxer
(also anti-vaxer)
nounantɪˈvaksəˌan(t)īˈvaksər
informal A person who is opposed to vaccination, typically a parent who does not wish to vaccinate their child.
 experts say several diseases that are avoidable are making a comeback due to anti-vaxxers who refuse to vaccinate their kids
 Example sentencesExamples
-  Those of us who are scientists are just as appalled by the anti-vaxxers as anyone.
 -  Despite the anti-vaxxers, vaccines are still a pillar of government policy.
 -  Not all outbreaks can be linked to anti-vaxxers, but some definitely have been.
 -  I'm not quite sure if that position is more or less bizarre than simply being an anti-vaxxer.
 -  You call people anti-vax as if it's a dirty word, but I would bet an anti-vaxxer would know more about vaccines than you do.
 -  A decade ago thimerosal was removed from the childhood vaccines that anti-vaxxers claimed were causing autism.
 -  I am a huge fan of science-based medicine with no patience and very little tolerance for the type of anti-vaxxers who -- despite the overwhelming landslide of evidence to the contrary -- still think that the MMR vaccination causes autism.
 -  In the last few years, I have noticed that derision towards anti-vaxxers has grown.
 -  I see you're also an anti-vaxxer and deny anthropogenic global warming.
 -  Does anyone know if antivaxxers also abstain from taking other medicine?
 
Origin
  
Early 21st century: from anti-vax.