Measles cases in the northwestern United States provide an overview of vaccine exemptions

DOSSIER – In this archival photo of January 25, 2019, a sign prohibiting access to children under 12 years of age and unvaccinated adults is held at the entrance of the PeaceHealth Southwest Medical Center in Vancouver , Washington. A measles epidemic has left more than 40 people sick in the northwestern Pacific. A call was made to eliminate a "philosophical" vaccine exemption that pushed 4% of children in the state of Washington to attend school without their usual childhood shots. (AP Photo / Gillian Flaccus, File)