Measles transmission during air travel, United States, December 1, 2008–December 31, 2011

SummaryBackgroundFlight-related measles contact investigations in the United States are coordinated by the Centers for Disease Control and Prevention (CDC). To evaluate the efficiency of CDC's measles protocol, we analyzed data from contact investigations conducted December 2008–December 2011.MethodsCases were defined as travelers diagnosed with measles that were infectious at the time of the flight. Passengers seated within 2 rows of the case-traveler and all babies-in-arms were defined as contacts. Contact information obtained from airlines was distributed to US health departments; reporting of outcomes was requested. We cross-referenced the National Notifiable Diseases Surveillance System and CDC's National Center for Immunization and Respiratory Diseases to identify unreported cases in passenger-contacts and in passengers not identified as contacts.ResultsOur evaluation included 74 case-travelers on 108 flights. Information for 2673 (79%) of 3399 passenger-contacts was provided to health departments; 9 cases of secondary measles were reported. No additional cases were identified.ConclusionOur evaluation provided evidence of measles transmission related to air travel. CDC's protocol efficiently identifies passengers most at risk of exposure and infection for flights into and within the United States.