Humanitarian emergencies, regardless of type and cause, have a number of common risk factors for communicable diseases inextricably linked to excess risk of morbidity and mortality which can come from vaccine–preventable diseases (VPDs). The reduction of VPDs is a significant aim of public-health interventions during crises. The WHO Strategic Advisory Group of Experts (SAGE) on Immunization carried out a comprehensive review of evidence on vaccination decision-making processes and considerations in humanitarian emergencies.