Updated April 8, 2025, at 10:44 a.m.
There are now two cases of measles in Colorado this year. The second case is a child under the age of 1 in Denver who recently traveled.
Health officials said Monday they confirmed the case in an unvaccinated Denver County infant resident. They recently traveled with family to an area of Chihuahua, Mexico, which is experiencing a measles outbreak.
The news was announced in a joint press release from the Colorado Department of Public Health and Environment and the Denver Department of Public Health and Environment.
Health officials urged Coloradans to check their vaccination status and monitor for symptoms like fever, cough, runny nose, red eyes and a rash that usually starts several days after exposure on the face and spreads.
People who were at the Denver Health emergency department on Sunday, April 6 from 10:30 a.m. to 4:30 p.m. may have been exposed, according to the release.
The news comes after a case was reported at the end of March, of a Pueblo adult who had traveled to an area of Mexico where there is an ongoing measles outbreak.
“Infants under 12 months are especially vulnerable to measles because they are typically too young to be vaccinated. This case is a stark reminder that families traveling internationally should delay unnecessary travel or talk to their health care providers about early MMR vaccination for infants, especially when visiting areas with known measles outbreaks,” said Dr. Rachel Herlihy, state epidemiologist and deputy chief medical officer at the Colorado Department of Public Health and Environment.
She expressed gratitude to Denver Health and the Denver Department of Public Health and Environment “for their swift action, expertise, and collaboration in identifying this case and protecting the broader community.”
Babies normally get the routine dose of measles, mumps, and rubella — or MMR vaccine — at 12 to 15 months. Measles is highly contagious and often severe, but it is a preventable disease. Health officials say the MMR vaccine remains the best protection.
Colorado’s vaccination rate for measles is 1 percentage point lower than needed to reach herd immunity, Herlihy said in a press conference when the first case was announced.
“What we call the community immunity or herd immunity threshold for measles is about 95 percent. So statewide we are falling short of that. So that does mean that Colorado is potentially at risk for outbreaks,” said the state epidemiologist, Rachel Herlihy.
As of April 3, 2025, a total of 607 confirmed measles cases were reported nationally, more than other recent years, according to the federal Centers for Disease Control and Prevention. In addition to Colorado, cases have been confirmed in Alaska, California, Florida, Georgia, Kansas, Kentucky, Maryland, Michigan, Minnesota, New Jersey, New Mexico, New York City, New York State, Ohio, Oklahoma, Pennsylvania, Rhode Island, Tennessee, Texas, Vermont, and Washington.
The U.S. has recorded two deaths this year; in 12 percent of the cases, the person was hospitalized.
Editor's note: This story was updated to clarify the age of the Denver resident who tested positive for measles. The resident is under the age of 1.
