Measles - United States, January 4-April 2, 2015

Abstract

Measles is a highly contagious, acute viral illness that can lead to complications such as pneumonia, encephalitis, and death. As a result of high 2-dose measles vaccination coverage in the United States and improved control of measles in the World Health Organization's Region of the Americas, the United States declared measles elimination (defined as interruption of year-round endemic transmission) in 2000. Importations from other countries where measles remains endemic continue to occur, however, which can lead to clusters of measles cases in the United States. To update surveillance data on current measles outbreaks, CDC analyzed cases reported during January 4-April 2, 2015. A total of 159 cases were reported during this period. Over 80% of the cases occurred among persons who were unvaccinated or had unknown vaccination status. Four outbreaks have occurred, with one accounting for 70% of all measles cases this year. The continued risk for importation of measles into the United States and occurrence of measles cases and outbreaks in communities with high proportions of unvaccinated persons highlight the need for sustained, high vaccination coverage across the country.

FIGURE 1

Number of reported measles cases (N = 159), by infection source, state, and county* — United States, January 4–April 2, 2015 Abbreviations: DC = District of Columbia; DE = Delaware; NJ = New Jersey. * Cases were reported from 18 states and the District of Columbia, and from 37 counties.

FIGURE 2

Percentage of U.S. residents with measles who were unvaccinated (n = 68), by reason for not receiving measles vaccine — United States, January 4–April 2, 2015 * Includes persons who were unvaccinated because of their own or a parent’s beliefs. ^† Includes persons ineligible for measles vaccination, generally those aged <12 months and those with medical contradictions. ^§ Includes eligible children aged 16 months–4 years who had not been vaccinated and international travelers aged 6–11 months who were unvaccinated. ^¶ Includes persons who were known to be unvaccinated and the reason was unknown, and those who were born before 1957 and presumed to be immune.