BACKGROUND: Providers are not required to report individual cases of varicella in New York City (NYC), but varicella outbreaks are reportable. Within the last decade, Orthodox Jewish populations in Brooklyn, NYC have experienced several outbreaks of vaccine preventable diseases. On May 2, 2016, a large medical practice in the Williamsburg neighborhood of Brooklyn notified the NYC Department of Health and Mental Hygiene (DOHMH) of an increase in varicella cases among the Orthodox Jewish community.
METHODS: DOHMH contacted all providers known to serve the Orthodox community in NYC to request that they report cases of varicella to DOHMH. Case investigation included patient interview and medical record review. Children were considered up-to-date (UTD) with varicella vaccination if they were aged 1-3 years with 1 dose and >4 years with 2 doses. Cases were classified using Council of State and Territorial Epidemiologists criteria. The number of varicella vaccine doses administered by age group during the outbreak was determined using the Citywide Immunization Registry (CIR).
RESULTS: The outbreak included 257 varicella cases, of which 99% (254) were Orthodox. Rash onset dates ranged from February 27 through August 5, 2016. Median age of cases was 3 years (range 2 months-33 years), of which 88% (226) were <5 years old. Of the 251 cases for whom vaccination records were available, 73% (182) were unvaccinated, 12% (29) were vaccinated but not UTD, and 16% (40) were vaccinated and UTD. Control measures included meetings with Orthodox community leaders and providers, notifications to providers citywide, and an Epi-X notification. DOHMH required exclusions of non-immune children from schools and child care facilities serving the affected community through the duration of the outbreak. DOHMH also placed advertisements in local papers and disseminated information at a community event with >10,000 attendees. Using the CIR, DOHMH sent 2,852 recall letters and 266 text messages to patients not UTD with vaccination from 9 practices that serve the community. The number of varicella vaccine doses administered to children aged 12 months-<5 years and 5-18 years in these 9 practices during the outbreak was 1784 and 730, respectively, representing a 5.2% and 7.3% increase from the corresponding months in 2015.
CONCLUSIONS: The outbreak was driven by delayed vaccination among young children with little spread beyond the Orthodox Jewish community. DOHMH implemented multiple control measures and identified an apparent increase in vaccine administration in the affected community during the time of the outbreak.