Vaccine hesitancy is a significant threat to public health and the anti-vaccination movement has played a significant role in communicable disease outbreaks. This commentary discusses the history and tactics of vaccine denialists and anti-vaccination groups. Anti-vaccination rhetoric is robust on social media platforms, and vaccine hesitancy has proven to impede the uptake of both established and new vaccines. Effective counter-messaging is needed to preemptively discredit vaccine denialists and reduce their influence on vaccine uptake. (PsycInfo Database Record (c) 2023 APA, all rights reserved).