Measles is one of the world’s most contagious diseases.
The U.S. Centers for Disease Control (CDC) has updated its travel advice following an increase in measles cases in the United States. Contrary to some media reports, the CDC has not issued a blanket warning to Americans not to fly if they are not vaccinated against measles.
The warning includes an advisory that travelers could be more susceptible to measles, which is highly contagious: “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. Infected travelers can bring the disease back to their home communities where it can spread rapidly among people who are not immune.”
However, the warning continues that the CDC recommends travelers be fully vaccinated against measles before traveling to any international destination, noting that measles cases are rising in countries worldwide. The agency notes that international travelers are at risk of contracting measles while abroad if they have not been fully vaccinated at least two weeks prior to departure, or have been rendered immune by having measles in the past. It is rare for US adults born after 1957 to have had measles.
Once a common childhood disease even in advanced economies, the World Health Organization (WHO) declared measles eradicated in the United States in 2000, and most measles cases before the early 2025 outbreaks were linked to international travel, but an increase in measles outbreaks since 2019 has put that status in jeopardy.
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The CDC issues a four-tiered threat advisory for specific conditions, and currently rates Global Measles at Level 1: Practice Usual Precautions. The advisory level has not changed with the Global Measles page’s latest update.
Measles is one of the world’s most contagious diseases, spread through coughing or sneezing. The virus that causes measles can live in the air or on surfaces for up to two hours after the infected person leaves the area. Measles is marked by a red, bumpy rash, high fever, cough, runny nose, or red watery eyes. Measles infections can be severe at any age and can lead to serious complications that can be permanently disabling or fatal.
The measles-mumps-rubella vaccine (MMR) should be administered to adults at least 28 days apart, and unvaccinated adults intending international travel should contact their physician for advice at least six weeks prior to travel, to give the vaccine enough time to reach full effectiveness. The CDC notes that some people, including pregnant women, a weakened immune system, some circulatory disorders, have had tuberculosis, have had other vaccines in the past four weeks, or a number of other reasons, should not get the MMR vaccine immediately. The CDC strongly encourages people who are unable or unwilling to get a full course of the MMR vaccine to speak with their doctor and consider postponing their trip.
The CDC notes that a full course of the MMR vaccine is 97% effective against measles.
In its latest update, the CDC also dropped its list of countries with the highest measles risk, now only saying that measles is “an ongoing risk around the world, and more international travelers are getting infected.”
Travelers who suspect they have contracted measles should immediately isolate themselves and call their medical provider for further instructions. They should also inform their medical provider if they have recently traveled internationally or to an area in the US that has experienced a measles outbreak.
Two hundred and eight measles cases and two deaths were reported in West Texas and parts of New Mexico in March 2025. The deaths, both in Texas, were the first U.S. measles deaths in more than a decade.
