Update on Reported Measles Cases in the U.S.

The Centers for Disease Control and Prevention (CDC) released an official health advisory on June 22, 2011 reporting that the U.S. is experiencing a high number of reported measles cases in 2011, many of which were acquired during international travel.

From January 1 through June 17 this year, 156 confirmed cases of measles were reported to the CDC. Of these cases, 136 were associated with importations from measles-endemic countries or countries where large outbreaks are occurring.

The imported cases involved unvaccinated U.S. residents who recently traveled abroad, unvaccinated visitors to the U.S., and people linked to these imported cases. To date, 12 outbreaks (3 or more linked cases) have occurred, accounting for 47% of the 156 cases. Of the total case-patients, 133 (85%) were unvaccinated or had an undocumented vaccination status.

Of the 139 case-patients who were U.S. residents, 86 (62%) were unvaccinated, 30 (22%) had undocumented vaccination status, 11 (8%) had received 1 dose of measles-mumps-rubella (MMR) vaccine, 11 (8%) had received 2 doses, and 1 (1%) had received 3 (documented) doses.

The increase in measles cases and outbreaks in the U.S. this year underscores the ongoing risk of importations, the need for high measles vaccine coverage, and the importance of prompt and appropriate public health response to measles cases and outbreaks.

For the entire health advisory, please visit the CDC website.