Measles in Colorado in 2026: check your family's MMR

Measles was declared eliminated from the United States in 2000, but it keeps coming back with travel and pockets of low vaccination. As of its October 15 update, the Colorado Department of Public Health and Environment had confirmed 26 measles cases in the state in 2026, with exposure sites posted in several counties over the year.

Measles is one of the most contagious diseases we know. Most people who aren't immune and are exposed will catch it. Here is how to make sure your family is protected.

Who needs an MMR shot

• Children: two doses, the first at 12 to 15 months and the second at 4 to 6 years.
• Adults with no record of immunity: at least one dose. College students, health care workers and international travelers should have two.
• Adults born before 1957: most are considered immune because they had measles as children.
• Babies 6 to 11 months who are traveling internationally, or to a U.S. area where measles is spreading: one early dose before the trip, then the usual two doses after the first birthday.

Two doses are about 97% effective at preventing measles. One dose is about 93% effective.

How to check your records

If you aren't sure whether you or your kids are up to date, Colorado's immunization registry (CIIS) has a public portal where you can look up records for your family. Military families who have moved through several duty stations often have records spread across systems, so it's worth a look before holiday travel. A blood test can also check immunity if records are lost.

Symptoms to know

Symptoms start 7 to 21 days after exposure: a high fever, cough, runny nose and red, watery eyes, followed a few days later by a rash that starts on the face and spreads down the body. People with measles can spread it from four days before the rash appears until four days after.

If you might have been exposed

The state posts exposure locations on its measles page. If you were at one of them during the listed times and you develop symptoms, call first. Phone your doctor, an urgent care or an emergency department, and tell them you may have been exposed to measles. That lets them see you without exposing other patients, including babies too young to be vaccinated.

Sources: Colorado Department of Public Health and Environment. Measles information (updated October 15, 2026). cdphe.colorado.gov. Centers for Disease Control and Prevention. Measles vaccination. cdc.gov.