Measles Outbreak among Members of the Orthodox Jewish Community —Brooklyn, New York, March-June 2013

Background: On March 13, 2013, an intentionally unvaccinated 17 year-old returned to New York City (NYC) from London while infectious with measles. This importation led to the largest outbreak of measles in the U.S. since elimination.

Methods: The outbreak period was March 13 to June 30, 2013. Suspected case investigations included patient interview, medical record review, and immunization record ascertainment. Measles IgM, IgG, and Polymerase Chain Reaction (PCR) were performed. Cases were residents of NYC and classified according to the CSTE clinical case definition. Exposed contacts were identified and control measures were conducted.

Results: Fifty-eight cases were confirmed with 6 generations of spread in two Brooklyn neighborhoods; all cases were among the Orthodox Jewish community. No cases had documentation of measles vaccination at the time of exposure. The outbreak began in Borough Park where the median age of cases (n=28) was 10 years (range 0-32yrs), and 89% of cases were part of three extended families of vaccine refusers. The outbreak spread to Williamsburg where the median age of cases (n=30) was 19 months (range 0-32yrs), and the primary reason for lack of vaccination was delay (47%). All cases met the case definition; 83% were confirmed by positive measles IgM or PCR and 17% by epidemiologic linkage. Complications included pediatric pneumonia and hospitalization of two pregnant women; one had a miscarriage and one delivered a baby with congenital measles. Over 3,500 contacts were identified. Control measures included administration of immunoglobulin or MMR post-exposure prophylaxis and home isolation of non-immune contacts. Expanded vaccination recommendations included an additional MMR dose for children 6 through 11 months of age and early administration of the second routine dose of MMR.

Conclusion: Importations of measles lead to continued risks of outbreaks in the U.S. and threaten elimination. This outbreak was propagated by a few extended families of vaccine refusers and children with vaccine delays in densely populated neighborhoods. The insular nature of the affected community and high population-level immunization coverage prevented spread outside the community. High vaccination coverage within the Orthodox Jewish community likely limited the scope of the outbreak.