Transmission of measles virus in healthcare settings during a communitywide outbreak

Abstract

Objective: To describe the epidemiology of measles in medical settings and to evaluate the implementation and effectiveness of the 1989 Advisory Committee on Immunization Practices (ACIP) guidelines for measles immunization in healthcare workers (HCWs).

Design: Confirmed cases of measles reported in Clark County, Washington, from March 14 to June 2, 1996, were analyzed for characteristics of cases occurring in medical settings. A questionnaire was used to assess employee immunization (95% response rate).

Setting and participants: Reported measles cases and HCWs at community hospitals, primary-care medical facilities, a health-maintenance organization, and a multispecialty group practice.

Results: Of 31 cases of measles, 8 (26%) occurred in HCWs, and 5 (16%) occurred in patients or visitors to medical facilities. Cases of measles occurred in HCWs who were not required to have proof of measles immunity as defined by the 1989 ACIP guidelines. The relative risk of measles in HCWs compared to Clark County adults was 18.6 (95% confidence interval, 7.4-45.8; P<.001). A survey of medical facilities revealed that 47% had an employee measles immunization policy; only 21% met ACIP recommendations and enforced their policies.

Conclusions: HCWs were at higher risk of measles than the adult population. Transmission of measles in medical settings was related to both deficiencies in, and lack of implementation of, the ACIP guidelines.