Data: The Washington Post; Map: Jacque Schrag/Axios
Most Colorado counties don't meet the herd immunity threshold for measles, with vaccination rates for kindergarteners below the 95% mark, per new data collected and analyzed by the Washington Post.
Why it matters: The state's measles cases are rising to historic levels, leaving local communities vulnerable to a virus public health officials say is preventable.
By the numbers: Colorado recorded 36 cases in 2025, according to state health department data, including in large counties like Denver, Arapahoe and El Paso.
Stunning stat: Only seven of Colorado's 64 counties meet the herd immunity threshold, data shows.
The big picture: Colorado isn't an outlier. The battle against infectious diseases like the flu and measles has taken a hit with sinking vaccination rates for children in many parts of the U.S.
The decline has set the U.S. up to lose its coveted elimination status for the first time in decades.
What's next: Federal health policy is shifting.
The Trump administration this week overhauled the childhood vaccination schedule by cutting recommended shots to 11, though the recommended list still includes a measles shot for kids.