CDC Issues Alert on Emerging Measles Threat

March 20, 2024

The CDC issued an alert this week to clinicians and public health officials following an increase in measles cases in the U.S. and around the world.

The health alert included a call to action to ensure infants 6 months and older receive their first shot against measles, mumps, and rubella (MMR) if they will be traveling internationally. Last month, the Philadelphia Department of Public Health announced the end of a measles outbreak following reports of cases during December and January.

“To prevent measles infection and reduce the risk of community transmission from importation, all U.S. residents traveling internationally, regardless of destination, should be current on their MMR vaccinations,” the CDC health alert noted.

Here’s what you need to know:

• Background:  There have been 58 cases reported during 2024 in the U.S., which is on par with the total number of cases for all of last year. About 93 percent were linked to international travel.
  • Most cases reported in 2024 have been among children aged 12 months and older who had not received the MMR vaccine.
• Very viral:  The risk for unvaccinated individuals is high. One person infected with measles can infect nine out of 10 unvaccinated individuals with whom they come in close contact.
• Vaccination rates:  The U.S. has seen a slight decrease in vaccination rates for MMR from 95.2 percent during the 2019–2020 school year to 93.1 percent in the 2022–2023 school year.
• The recommendations:  Children who are not traveling internationally should receive their first dose of MMR between 12–15 months old and their second dose at 4–6 years.
  • Infants traveling internationally between 6–11 months should receive one dose of MMR vaccine before departure, and two more doses of MMR vaccine—the first should be administered when the child is age 12–15 months and the second at least 28 days later.
• Key insight:  A 2 percent drop in vaccination rates from 95 percent to 93 percent means an additional 250,000 kindergartners who don’t have protection against MMR, the health alert noted.

“Given currently high population immunity against measles in most U.S. communities, the risk of widescale spread is low. However, pockets of low coverage leave some communities at higher risk for outbreaks,” the health alert noted.

The health alert includes recommendations for health departments and providers. Review the latest recommendations online.