Measles among adults, United States, 1985-1995

Abstract

Objective: To report the incidence and characteristics of adult measles cases in the United States and address the adequacy of current vaccination policies to eliminate measles transmission.

Methods: Confirmed measles cases reported to the Centers for Disease Control and Prevention (CDC) from 1985 through 1995 were reviewed. Demographic data, exposure setting, and vaccination status of cases were analyzed and incidence rates calculated based on U.S. census data.

Main outcome measures: Age-specific incidence rates of measles and exposure setting.

Results: Of the 75,204 reported measles cases of known age, 16,006 (21.3%) occurred in adults (persons > 19 years of age). The incidence in persons < 19 years of age (7.8/100,000) was 9.6 times that of all adults. Of 11,520 adult measles cases for whom vaccination status was reported, 8,055 (69.9%) indicated no prior receipt of measles vaccine. Exposure setting was unknown for the majority of adult measles cases (8,475, 52.9%); most frequently reported were college or school (2840, 17.7%), home (1443, 9.0%), or a medical setting (1286, 8.0%). International travel was associated with 289 (1.8%) adult cases. From 1993 to 1995, incidence rates in all age groups were at record low levels, with adults contributing 29.5% (467/1584) of reported cases.

Conclusion: Although adults accounted for a steadily increasing proportion of measles cases during the study period, incidence rates in all age groups have decreased. Most adults who had measles were susceptible because of lack of vaccination rather than vaccine failure. This analysis supports current strategies to ensure the immunity of school/college-aged populations, and health care workers.