CDC Updates Measles Travel Warning Amid Spread in Airplane

Last week, the U.S. Centers for Disease Control and Prevention (CDC) intensified its warning about the risk of contracting measles while traveling due to an increase in cases among travelers. The CDC has tallied dozens of cases so far this year in travelers who were infectious while flying on airplanes within the U.S. The CDC said most people who bring measles into the United States are unvaccinated U.S. residents who get infected during international travel.

The number includes six cases linked to a Turkish Airlines flight that landed at Denver Internation Airport on May 13, NBC News reported. The Colorado Department of Public Health and Environment said that four of the patients had been on the plane. Two unrelated adults from El Paso County, Colorado, were at Denver International Airport around the same time on May 14. These two adults were exposed at the airport before getting sick. 

The CDC now recommends that all international travelers should be fully vaccinated against measles with the measles-mumps-rubella (MMR) vaccine, according to CDC’s measles vaccination recommendations for international travel. The recommendation includes an early dose for infants 6–11 months old and a total of two doses at least 28 days apart for anyone 12 months old or older without adequate evidence of immunity.

As of May 29, The CDC has confirmed 1,088 measles cases this year in 32 states. (South Dakota reported its first measles case of the year on Monday, marking the 33^rd state to report at least one case in 2025.) Most cases (96%) are in unvaccinated or vaccination status unknown individuals. A majority of cases (67%) are in children and teens aged 19 or younger. The U.S. is nearing the total measles cases reported in 2019, which is 1,274 and the highest number of measles cases since the disease was declared eliminated in the U.S. in 2000.

Meanwhile, new research from Johns Hopkins University, published Monday in the journal JAMA, found that MMR vaccination rates among children have dropped in more than three-quarters of U.S. counties, with an average drop of 2.7% between 2017 and 2024.

The CDC and experts also know measles cases are underreported. For example, CNN’s tally is 1,157 from state health departments. In turn, WastewaterSCAN has developed the first national wastewater monitoring program to detect measles in places where people are infected with the virus. It has the potential to identify possible cases days before an individual shows symptoms or seeks care. CNN reported the tool is available for use in nearly 150 wastewater treatment facilities across 40 states and works like wastewater surveillance used during the COVID-19 pandemic.