US health officials have changed their advice to international travellers about measles, saying that Americans should be vaccinated against the virus no matter where they’re going. US residents are recommended to get measles-mumps-rubella shots, anyway. However, the Centers for Disease Control and Prevention (CDC) previously emphasised the importance of vaccination for travellers going to countries with outbreaks. Also read | US measles cases surpass 700 with outbreaks in 6 states

Things to know about measles outbreak in the US

Last week, the CDC updated its guidance to call for vaccinations for travellers going to all other countries. This change reflects the growing concern about measles transmission during travel, as highlighted by a recent Colorado outbreak stemming from an international flight. As of May 29, 2025, a total of 1,088 confirmed measles cases were reported, according to the CDC.

Ashley Darcy-Mahoney, a researcher at George Washington University’s nursing school, called the update significant. She noted that an outbreak in Colorado last month stemmed from an international flight that landed in Denver. The CDC travel notice change reflects a recognition that people are being exposed to measles not just in countries where it’s spreading but also in airplanes and during travel.

“We’re seeing a shift from localised outbreaks to transmission in transit,” and the CDC seems to be responding to that, Darcy-Mahoney said. The travel notice advises two doses for all Americans ages 1 and older. An early dose is advised for traveling infants ages 6 months to 11 months. The U.S. has seen more than 1,000 measles cases so far this year.

Measles is caused by a highly contagious virus that’s airborne and spreads easily when an infected person breathes, sneezes or coughs. It is preventable through vaccines, and has been considered eliminated from the US since 2000. Cases and outbreaks in the US are frequently traced to someone who caught the disease abroad. 

The CDC says more than twice as many measles have come from outside of the US compared to May of last year, and most of those are in unvaccinated Americans returning home. In 2019, the US saw 1,274 cases and almost lost its status of having eliminated measles.

What are the symptoms of measles?

Measles first infects the respiratory tract, then spreads throughout the body, causing a high fever, runny nose, cough, red, watery eyes and a rash. The rash generally appears three to five days after the first symptoms, beginning as flat red spots on the face and then spreading downward to the neck, trunk, arms, legs and feet.

When the rash appears, the fever may spike over 104 degrees Fahrenheit, according to the CDC. Most kids will recover from measles, but infection can lead to dangerous complications such as pneumonia, blindness, brain swelling and death.

How can you treat measles?

There’s no specific treatment for measles, so doctors generally try to alleviate symptoms, prevent complications and keep patients comfortable.

What do you need to know about the MMR vaccine?

The best way to avoid measles is to get the measles, mumps and rubella vaccine. The first shot is recommended for children between 12 and 15 months old and the second between 4 and 6 years old. Getting another MMR shot as an adult is harmless if there are concerns about waning immunity, the CDC says. People who have documentation of receiving a live measles vaccine in the 1960s don’t need to be revaccinated, but people who were immunized before 1968 with an ineffective vaccine made from “killed” virus should be revaccinated with at least one dose, the agency said.

People who have documentation that they had measles are immune, and those born before 1957 generally don’t need the shots because so many children got measles back then that they have “presumptive immunity.”

Note to readers: This article is for informational purposes only and not a substitute for professional medical advice. Always seek the advice of your doctor with any questions about a medical condition.