Colorado declares first measles outbreak of 2026, tied to Broomfield schools

• The state confirmed 36 measles cases in 2025, mostly among unvaccinated patients, after just six cases total over the previous decade.

The latest: The newest case involves a Broomfield Heights middle school student who had contact with one of the two earlier cases, both Broomfield High students.

• All three students were unvaccinated.

Threat level: Officials are scrambling to track exposures, but the lack of a travel link to the first case suggests measles may already be circulating undetected in the area, the Colorado Department of Public Health (CDPHE) said.

• The students may have exposed people at locations in Lafayette, Louisville and Westminster between Feb. 17 and Feb. 26.
• Because measles has an incubation period of up to 21 days, symptoms could appear as late as March 20.

By the numbers: Both Broomfield schools exceed the 95% vaccine threshold typically cited for herd immunity, while Broomfield and Adams counties are around 92%.

• "Measles is a highly contagious, but preventable disease. Getting the measles, mumps, and rubella vaccine is the best way to protect yourself, your family, and your community," CDPHE officials said in a statement.

Zoom in: The schools are ramping up cleaning and requiring unvaccinated students and staff to stay home during the 21-day incubation window.

• Boulder Valley spokesperson Randy Barber said the outbreak designation does not require any extra steps, but the district will continue to follow CDPHE guidance.
• Barber said the district has remote learning protocols in place for students in quarantine.