Epidemiologic Analysis of a Postelimination Measles Outbreak in Central Ohio, 2022-2023.

Importance: Postelimination outbreaks threaten nearly a quarter century of measles elimination in the US. Understanding these dynamics is essential for maintaining the nation's measles elimination status. Objective: To examine the demographic characteristics and transmission dynamics of the 2022 to 2023 central Ohio measles outbreak. Design, Setting, and Participants: This cross-sectional study used electronic medical records and publicly available measles reports within an extensive central Ohio primary care network involving inpatient and outpatient settings. Participants included 90 children in Ohio with confirmed measles cases in 2022. Exposure: The exposure of interest was confirmed measles cases in Ohio in 2022. This included 5 internationally imported cases and 85 locally acquired cases. Main Outcomes and Measures: The primary outcome involved documenting and analyzing confirmed measles cases in Ohio in 2022, focusing on demographic characteristics, immunization status, and transmission links in outbreak-related cases. Results: This study analyzed 90 measles cases (47 [52.2%] male participants) in Ohio during 2022. Most participants self-identified as African or American Black (72 [80.0%]), with additional race categories including Asian, Hispanic, multirace (6 [6.7%]), White, and unknown (6 [6.7%]). Most participants were of Somali descent (64 [71.1%]), with additional ethnicity categories including American (16 [17.8%]), Guatemalan, Nepali, and unknown (6 [6.7%]). Participants were predominantly younger than 6 years (86 [95.5%]), unimmunized (89 [98.9%]), and resided in Franklin County, Ohio (83 [92.2%]). Prior to November 20, 2022, all cases occurred among unimmunized children of Somali descent in the Columbus area. Nosocomial superspreading events expanded the outbreak beyond the initially affected community. Conclusions and Relevance: This cross-sectional study of measles cases in Ohio during 2022 found that the outbreak primarily affected unimmunized children of Somali descent, highlighting the necessity for culturally tailored public health strategies to maintain measles elimination in the US. These findings underscore the importance of implementing targeted interventions and enhancing community engagement to increase vaccination rates.