Vaccinations are among the most cost-effective and widely used public health interventions but have provoked popular resistance, with compulsory vaccination framed as an unwarranted state interference. When the US Food and Drug Administration (FDA) approved a human papillomavirus (HPV) vaccine in 2006, conservative religious groups strongly opposed a mandate, arguing it would condone premarital sex and undermine parental rights. Yet Governor Rick Perry signed an executive order in 2007 making Texas the first state to enact a mandate—later revoked by the state legislature.