Adults in the United States who were vaccinated against measles decades ago may need a new dose depending on when they received the shot and their exposure risk, according to public health experts battling the nation's largest outbreak since the virus was deemed eliminated in 2000.
Up to 10 percent of the 695 confirmed measles cases in the current outbreak occurred in people who received one or two doses of the vaccine, according to the U.S. Centers for Disease Control and Prevention.
The figure illustrates what can happen when a large number of individuals, even those who have been vaccinated, are exposed to the measles. CDC recommends that people who are living in or traveling to outbreak areas should check their vaccination status and consider getting a new dose.