LB16. The Role of Adults in the Measles Outbreak in New York State Outside of New York City, 2018–2019

BACKGROUND: The United States is experiencing the largest measles outbreak since elimination was declared in 2000, with the majority of cases in NYS reported in undervaccinated communities. The objective of this evaluation was to describe adult measles cases in the NYS measles outbreak outside of New York City (NYC). METHODS: We included all confirmed cases aged ≥18 years in NYS residents (excluding NYC) during October 1, 2018–July 25, 2019 that met the CSTE measles case definition. We defined measles cases attributable to adults as the sum of measles cases among adults and children who contracted disease directly from adults. RESULTS: Among 371 confirmed measles cases, the median age was 5.5 years (range: 1 day to 64 years); 79 (21%) were in adults, 4 (5%) of whom were born before 1957 (3 unvaccinated and 1 with unknown vaccine status). Among the 75 cases born during or after 1957, 65 (87%) were unvaccinated or had unknown vaccine status, while 3 had one dose and 7 had 2 doses of measles vaccine. Notably, 5 of 11 internationally imported measles cases were adults, and all were unvaccinated or had unknown vaccine status. During the first month of the outbreak, 26 of the 51 (51%) cases were attributable to adults; of the 26, 15 (58%) were in adults and 11 (42%) were in children who acquired infection from adults (Figure 3). CONCLUSION: The majority of measles cases occurred in unvaccinated children emphasizing the importance of ongoing and focused efforts on pediatric vaccination. However, measles cases in unvaccinated adults played an important role in both importations and disease transmission early in the outbreak. These data strongly support current recommendations of 1 dose of measles, mumps, rubella vaccine (MMR) for most adults and 2 doses of MMR for adults traveling internationally and at high-risk such as those in outbreak areas, as determined by local/state public health. [Image: see text] [Image: see text] [Image: see text] DISCLOSURES: Kirsten St. George, MAppSc, PhD, Akonni Biosystems (Other Financial or Material Support), ThermoFisher (Grant/Research Support), Zeptometrix (Other Financial or Material Support, royalty generating collaborative agreement). .