The Centers for Disease Control and Prevention is warning Americans traveling abroad to make sure they are up-to-date on their measles vaccines at least six weeks before their trip, in new guidelines announced Wednesday, as the number of cases rise around the world. File photo by James Gathany/Centers for Disease Control and Prevention via Wikimedia Commons

“Traveling for spring break? Make sure you and your family are up-to-date on measles vaccine, especially before international travel,” the CDC wrote in a post on X. “The measles vaccine is safe and effective. Two doses of MMR vaccine are about 97% effective at preventing measles.”

The CDC also added Russia and Malaysia on Wednesday to its map of 46 countries dealing with measles outbreaks.

“Measles spreads rapidly and may become a risk to travelers in places not included on the list,” the agency warned. “CDC recommends all travelers are fully vaccinated against measles when traveling to any international destination.”

The CDC recommends, and school enrollment requires, two doses of the measles, mumps and rubella vaccine by the age of six. For any adults born after 1957, who are not sure if they have had the vaccine, the CDC recommends at least one dose of MMR.

Measles, which can cause rash, high fever, cough, runny nose or red and watery eyes, is highly contagious and is also on the rise in the United States.

On Tuesday, the Chicago Department of Public Health confirmed four new cases of measles at a migrant shelter, bringing the number of cases in the past four days up to five.

The CDPH said it provided measles vaccines for 900 people at the shelter, while trying to determine the immunization status of 700 residents.

“Because some Chicagoans on the whole are unvaccinated, there remains an opportunity for the virus to spread,” CDPH warned in a statement.

According to the CDC, 45 recent measles cases have been detected across 17 states.