Ya know if the “Government(at ALL Levels)” hadn’t have LIED to the American People for DECADES then CRACKPOTS like the “anti-Vaccine” crowd would not have ANY Credibility! A lot of the stuff that the “Government” has said are/were HARMLESS have been proven as PURE Lies!
It's largely a leftist movement; the Prius driving granola crowd are the anti-vax base. But there's pockets of it across all groups and ideologies, much like anti-Semitism, another ancient fear borne out of myth and superstition.