Colorado health officials have confirmed two new measles cases, reigniting concerns about the disease’s quiet resurgence — even among the vaccinated.
The Colorado Department of Public Health and Environment (CDPHE) said one case involves a child under five years old from El Paso County. The child was vaccinated, officials confirmed, but had recently traveled with family to Ontario, Canada, where a measles outbreak is currently unfolding.
The second case? An adult from Arapahoe County who passed through Denver International Airport on Tuesday, May 13 — overlapping with a known exposure period from an out-of-state traveler. That individual is now being monitored after developing symptoms consistent with measles.
A Growing Pattern
These are not isolated events. They’re part of a slow but visible uptick in measles activity across the country.
While the U.S. eliminated endemic measles transmission in 2000, travelers remain a key vulnerability — and these new Colorado cases underline that.
“Travel is the most common way measles re-enters the U.S.,” a CDPHE spokesperson said. “And airports, especially large international hubs like DIA, are high-risk zones for exposure.”
Yes, Even the Vaccinated
The El Paso County case is notable because the child was vaccinated — sparking questions about how that’s possible.
Health officials were quick to clarify: the measles-mumps-rubella (MMR) vaccine is very effective, but not 100%.
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About 93% of people who receive one dose are protected
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Two doses boost that protection to 97%
Breakthrough infections are rare, but they can happen — especially if the immune system is still developing, as in very young children. The fact that the child had traveled to an outbreak zone increased the likelihood of exposure.
Measles by the Numbers
Here’s a quick look at measles symptoms, spread, and impact — especially for those unfamiliar with the disease that many thought had vanished:
| Key Facts About Measles | |
|---|---|
| Transmission | Airborne (coughing/sneezing); can linger in the air for hours |
| Contagious Before Symptoms? | Yes — up to 4 days before rash |
| Incubation Period | 7–21 days after exposure |
| Initial Symptoms | High fever, cough, runny nose, red eyes |
| Later Symptoms | Rash (usually starts on face, spreads), white spots inside mouth |
| Complications | Ear infections, pneumonia, brain swelling, death (rare but possible) |
According to the CDC, measles can be deadly, especially in children under five and those with weakened immune systems.
DIA Exposure Triggers Broad Alert
The adult patient in Arapahoe County reportedly passed through Denver International Airport during the May 13 exposure window. CDPHE is working with local and federal health authorities to identify potential contacts.
Passengers and workers who were in Concourse A and baggage claim during that time are being advised to monitor symptoms and contact their healthcare provider if they become ill — particularly if they haven’t been vaccinated.
A Reminder to Check Your Status
Health officials are once again emphasizing the importance of the MMR vaccine, not just for kids, but for adults who may not know their vaccination history.
“If you’re unsure whether you received two doses of MMR, talk to your doctor,” said Dr. Brian Erstad, a pediatric infectious disease specialist in Colorado Springs. “In many cases, it’s safe to get vaccinated again rather than take the risk.”
He also noted that people born before 1957 are generally presumed immune, as they were likely exposed before widespread vaccination began.
What’s Next?
For now, both Colorado cases appear to be contained — but the concern remains. The CDPHE says it will continue to monitor for additional infections and urges the public to stay alert, especially those planning international travel.
And while no outbreak has been declared in Colorado, health officials stress that vaccination coverage is the state’s best line of defense.
As Dr. Erstad puts it: “It’s not just about protecting yourself — it’s about protecting your entire community.”
