CDC Health Advisory Says This ‘Ongoing Risk’ Leaves Travelers Vulnerable on Public Transport, Planes, Trains, and More

A recent outbreak of measles has caused a leading health authority to update guidance.

The Centers for Disease Control and Prevention (CDC) recently updated its travel advisory and is encouraging international travelers to get vaccinated (or confirm their vaccination status) against the measles virus before heading abroad. 

“Measles is an ongoing risk around the world, and more international travelers are getting infected,” the CDC advisory reads. “Travelers can catch measles in many travel settings including travel hubs like airports and train stations, on public transportation like airplanes and trains, at tourist attractions, and at large, crowded events.”

In response to the ongoing risk, the CDC advises all travelers going to or from an international destination to be fully vaccinated against measles. For travelers who are not yet vaccinated or unable to get vaccinated, the government agency encourages people to consult a medical professional and consider postponing their trip until the risk is assessed. 

The advisory was last reviewed on May 28 by the CDC.

Denver International Airport is one site that health authorities have closely monitored as a source of several recent measles cases. At least four passengers on a recent Turkish Airlines flight reportedly caught measles, according to the Colorado Department of Public Health and Environment. 

“Public health officials are notifying members of the public of additional areas for potential measles exposures, as a result of these confirmed cases,” the Colorado advisory states. “The adults are unrelated, but were at Denver International Airport around the same time on Wednesday, May 14.”

There have been 1,088 confirmed cases of measles in the United States in 2025, according to the CDC. Ninety-six percent of the cases have been unvaccinated or whose status was unknown, and only 12 percent of cases have required hospitalization. According to CBS News, a CDC spokesperson said there have been 62 cases of measles that tie back to international travel thus far in 2025.

The virus spreads through coughing and sneezing, and can remain in the air for up to two hours, the CDC advisory states.