Mumps Outbreak in Orthodox Jewish Communities (2010)

 Despite high immunization coverage, the outbreak affected hundreds of individuals, prompting questions about the effectiveness of mumps-containing immunizations in real-world conditions. Data revealed that 89% of the infected teenagers had received two doses, and another 8% had received one dose, meaning 97% of the cases occurred among individuals who had already been immunized. This raised concerns about primary and secondary vaccine failure where the immune system either does not respond adequately after vaccination or immunity wanes over time. The outbreak highlighted the challenges of relying solely on immunization coverage to prevent transmission, particularly in densely populated communities with close social interaction. It also underscored the need for continuous evaluation of long-term protection, especially for components like mumps, which may not provide lifelong immunity in all individuals despite adherence to current recommendations.