Characterizing measles healthcare facility exposures-December 2023-September 2025-New York City

When people develop measles (cases), healthcare facility exposures are common and result in many potentially exposed people requiring resource-intensive control measures. We summarized exposures and transmission among people exposed to measles (contacts) in healthcare settings in New York City (NYC).

NYC Health Department's surveillance data of NYC contacts exposed to measles cases in any NYC healthcare facility during December 2023-September 2025 was analyzed as a retrospective descriptive study. Characteristics summarized included measles transmission, immunity status, post-exposure prophylaxis (PEP) administration, facility setting, and time of measles exposure.

Of 2,122 healthcare contacts to 28 cases, no secondary cases occurred. 1,285 (60.6%) were vaccinated or had other evidence of immunity, 618 (29.1%) were adults with unknown immunity, 124 (5.8%) were not immune and received PEP, and 95 (4.5%) were not immune and did not receive PEP. Most contacts were exposed in emergency departments and/or hospital inpatient settings (1,406; 66.3%). Among 1,028 contacts with known time of exposure (48.4% of all contacts), 785 (76.4%) overlapped with the case in the healthcare facility, 146 (14.2%) arrived within 1 hour and 97 (9.4%) arrived 1-2 hours after the case left or was isolated.

Most contacts exposed to measles in NYC healthcare facilities had presumptive immunity or were adults with unknown immunity. No transmission occurred among 2,122 exposed contacts, including non-immune contacts. Given no secondary transmission and resource-intensive control measures, relying solely on time-based measles exposure definitions may be overly broad. Incorporating strategies like facility air exchange data might better assess transmission risk.