BROOMFIELD, Colo. — About 80 students and staff are being told to stay home from school as Colorado deals with its first measles outbreak of 2026. The exclusions comes after the Colorado Department of Public Health and Environment identified a third measles case related to two others connected to Broomfield High School.
There's been a total of four measles cases in the state this year, according Dr. Rachel Herlihy, the state's epidemiologist. From 2014-2024, the state saw between zero and two measles cases each year, according to CDPHE's measles webpage. Last year, Colorado recorded a total of 36 cases.
The Colorado Department of Public Health and Environment identified three counties linked to the latest outbreak: Broomfield, Adams and Arapahoe counties.
- Denver7 has been closely following confirmed cases of measles in Colorado since the number of cases exploded last year amid a multi-state outbreak in the U.S. Explore the map below to see where cases have popped up in 2026:
The outbreak is now forcing "around 80 individuals" to be "excluded from school settings," according to Dr. Herlihy. The state's epidemiologist added "that would be across the high school and the middle school, and that's going to be mostly students that are unvaccinated, but also a small number of staff as well."
Measles is a highly contagious viral infection that spreads through the air and can remain airborne for up to two hours.
Read more here about the outbreak, what to do if you think you've been exposed and more.
The two-dose series of the MMR vaccine has a 97% efficacy rate against infection, but about 3 in every 100 people can still get infected if exposed to the virus, according to the U.S. Centers for Disease Control and Prevention (CDC). Vaccinated individuals will usually develop milder symptoms and are less likely to spread it to others, according to state health officials.
On Thursday, Denver7's Veronica Acosta spoke with Jason Vahling, the Director of Public Health and Environment with the City and County of Broomfield.
Vahling said its working with the Boulder Valley School District to contact trace.
"When we became aware of the first case at Broomfield High School, we started our contact tracing and case investigation that involves really looking at the students that are unvaccinated, students and staff, making sure we're identifying them, and then taking the appropriate protocols or measures, which involves excluding them from school until they can show proof of immunity or quarantining when appropriate," Vahling said.
A spokesperson for CDPHE clarified the people who've been excluded from school settings are not under quarantine; some could simply be at high risk for contracting measles.
Anyone who believes they may have been exposed — especially those who have not been vaccinated with the MMR vaccine — should monitor for symptoms for 21 days and avoid public gatherings or high-risk settings, health officials said in a news release.
Symptoms to watch out for include anything from a fever, a cough, a runny nose and red, watery eyes followed by a rash that typically starts on the face and then spreads to the rest of the body.
Unvaccinated people exposed to the virus can get the MMR vaccine 72 hours after exposure (but before symptoms are present) to prevent an infection, according to health officials. Immunoglobulin (IG), if administered within six days of exposure, may also be used in some circumstances, they added.
Denver7 asked both Vahling and Dr. Herlihy if they were working on setting up vaccine clinics in response to the outbreak.
"We are actively having conversations with our local public health partners about clinics, but certainly encourage folks to to seek out vaccination," Dr. Herlihy said.
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