Measles immunity in employees of a multihospital healthcare provider

To assess the potential for nosocomial measles transmission by measuring seropositivity among healthcare workers in Utah.

Blood specimens were collected for measurement of measles IgG antibody by enzyme immunoassay (EIA). Individuals with undetectable or equivocal antibody levels were considered at risk for infection. Employees were grouped according to the decade of their birth, and analyses of serological findings were done by the Mantel-Haenszel chi-square test for trend.

The study was performed in a healthcare organization comprised of six urban and 10 rural hospitals.

Employees (n = 5825) were tested regardless of age, history of disease, or immunization.

There were 599 employees (10.3%) who were nonimmune. A trend showing age-related differences in immunity was not noted among employees born prior to 1957 (4.7% nonimmune). However, for employees born after that time, there was a significant age-associated increase in the percentage of susceptible individuals (P = 0.00001). The rate of susceptibility was 8.1% for individuals born between 1957 and 1959, 16.3% for individuals born during the 1960s, and 33.7% for those born in the 1970s.

We concluded that employees born after 1960 represent a material risk for transmission of measles in the hospital setting. Despite the low percentage of susceptibility among those born before 1957, the 144 susceptible individuals in this group also are at risk for measles transmission. Thus, during periods of increased measles prevalence, we would recommend screening all healthcare workers regardless of age and vaccinating those who are susceptible.