The agency warns of rising in-transit infection risk as U.S. cases hit their highest level since 2019.
The Centers for Disease Control and Prevention (CDC) has issued a major update to its measles vaccination guidance, urging all Americans traveling internationally—regardless of destination—to get vaccinated amid a resurgence of the disease in the United States and abroad.
“All international travelers should be fully vaccinated against measles with the measles-mumps-rubella (MMR) vaccine,” the CDC said in a May 28 update. The agency recommends two doses for everyone aged 12 months or older, spaced at least 28 days apart, and a single early dose for infants aged 6 to 11 months who will be traveling.
“Most people who bring measles into the United States are unvaccinated U.S. residents who get infected during international travel,” the agency stated.
The new travel alert marks a significant shift from previous CDC guidance, which prioritized vaccination only for those heading to outbreak-prone regions. Experts say the expanded recommendation reflects a growing risk of infection in transit—especially on airplanes and in airports.
“We’re seeing a shift from localized outbreaks to transmission in transit,” said Ashley Darcy-Mahoney, a professor at George Washington University’s nursing school.
That risk was recently illustrated in Colorado, where state health officials linked six confirmed measles cases to a single infected passenger aboard a Turkish Airlines flight that landed at Denver International Airport on May 13. Among the infected are three Colorado residents who were on the flight, including a vaccinated adult from Arapahoe County, and two unrelated unvaccinated adults from El Paso County who were at the airport the following day and likely exposed to the virus there. A fourth case from the flight involved an out-of-state passenger.
All six individuals are recovering at home, but the outbreak prompted public health alerts and raised concerns about airborne exposure at the Denver airport. Health officials say both El Paso County residents were at the airport around the same time on May 14 and may have contracted measles through the shared airspace.
“Getting vaccinated is the best way to protect yourself, your family, and your community,” the Colorado Department of Public Health and Environment said in a June 1 statement. “Measles is highly contagious and can lead to serious health problems—but it is a vaccine-preventable disease.”
By Tom Ozimek
