Methods: The New York City Health Department interviewed patients and reviewed clinical, laboratory, and immunization records. Cases were considered part of the outbreak if they met the clinical case definition and had an epidemiologic link to the Orthodox Jewish community of Brooklyn. Exposed persons were identified. Control measures were implemented.
Results: As of May 5, 2016, 238 cases were reported in 4 neighborhoods of Brooklyn; the outbreak surged in summer due to transmission at camps. Median age of cases was 8 years (range 0-68 years); 198 (83%) were aged ≤18 years including 61 (26%) <1 year of age. Among child cases, 55 (28%) were unvaccinated, 28 (14%) were vaccinated but not up-to-date with pertussis containing vaccine, 114 (58%) were up-to-date, and 1 (<1%) had unknown immunization history. Among mothers of infant cases, 54 (89%) had not received Tdap vaccine during pregnancy, 4 (7%) had received vaccine, and 3 (5%) were unknown. Five infant cases were hospitalized; no deaths occurred. Among cases, 215 (90%) received antibiotics treatment, and 201 (84%) were tested by PCR, 52% of which were positive. The median time from medical visit to report to public health was 4 days (range 0-137 days) and improved as the outbreak progressed. Outbreak control measures included alerts to providers, letters to schools and parents of school children, audits of schools and daycares for immunization compliance, exclusion of exposed students not up-to-date with vaccination, patient recall for vaccination, and advertisements in local papers. In total, 935 additional exposed persons were identified; exposures occurred within households and at camp, school, and other congregate settings.
Conclusion: Delays in vaccination among young children and limited Tdap vaccination among pregnant women contributed to the start of the outbreak. The outbreak was propagated by cases among vaccinated adolescents and adults; this highlights concerns around vaccine effectiveness and waning immunity. Delays in reporting to public health, particularly early in the outbreak, further hindered implementation of outbreak control measures.
R. J. Arciuolo,
J. R. Zucker, None
J. B. Rosen, None
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