MEASLES IMMUNITY AMONG COMMUNITY HOSPITAL EMPLOYEES

Objective: To define measles immunity rates among employees at 2 hospitals during a community outbreak in 1990. Design: Cohort survey using enzyme-linked immunosorbant assay (ELISA) and questionnaire. Setting: Two community hospitals. Participants: Seventy-six percent of 2,060 employees. Results: Seven percent (115/1566) of participants lacked ELISA-defined measles immunity. Among employees whose ages were known, 14% (64/467) of those born after 1956 and 5% (50/1086) of those born before 1957 lacked serologic evidence of immunity. Fifty-eight percent of the susceptible persons had substantial patient contact. With ELISA results as the reference for immunity, the predictive value of an undocumented positive history of measles disease or vaccination was 95%; the predictive value of a negative history of both was 52%. Measles developed in 7 employees. Conclusions: A substantial number of hospital employees lacked ELBA-defined measles immunity, including many who had patient contact or who had been born before 1957. Undocumented disease and vaccination histories were not adequate predictors of serologic status. This study supports the recommendations and suggestions of the Immunization Practices Advisory Committee that hospitals should require documented evidence of measles immunity from employees who have patient contact.