Measles After Vaccination: Less Severe but Still Contagious

Whereas naturally acquired measles results in lifelong immunity, immunity after vaccination may not be permanent. After the introduction of the attenuated measles vaccine in the U.S. in 1966, several outbreaks of measles occurred. As a result, at least two doses of measles vaccine have been recommended since 1989. Although this practice is presumed to result in better protection, few studies have looked at actual protection. To examine this issue, the authors reviewed 232 confirmed cases of measles in people with known vaccination status, reported from January 2000 through December 2015 to the California Department of Public Health. Among these cases, 186 (80%) had never been vaccinated, 20 (9%) had a single dose of vaccine, and 26 (11%) ha…