DENVER — Measles may be spreading undetected in Delta County after a vaccinated child with no known connection to other cases in the state and no history of recent out-of-state travel tested positive for the virus, state health officials said Saturday.
This case — the first for Delta County since a multi-state outbreak of the virus crossed into Colorado last year — suggests there may be more cases of the highly contagious disease going around in the area due to the lack of a clear source of infection, according to a spokesperson with the Colorado Department of Public Health and Environment. Delta County Public Health is investigating the case.
The patient, a child under the age of 5, may have exposed people to measles at the following two locations:
- Delta Health Urgent Care, located at 296 Stafford Lane, on Wednesday, May 27 from 5:30 p.m. - 8:30 p.m.
- Delta Health Emergency Center, located at 1501 3rd St., on Wednesday, May 27 from 6:30 p.m. - 9:30 p.m.
School immunization data from the CDPHE shows the Delta County School District 50J, which covers Delta County, had a 86.5% vaccination rate for the MMR vaccine as of the 2024-25 school year — well below the 95% herd immunity threshold needed to prevent a rise in cases in the community.
While the two-dose series of the MMR vaccine has a 97% efficacy rate against infection, about 3 in every 100 people can still get infected if exposed to the virus for a prolonged period of time, according to the U.S. Centers for Disease Control and Prevention. Vaccinated individuals will usually develop milder symptoms and are less likely to spread it to others, according to state health officials.
What to do if you believe you were exposed
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.
State health officials said those who were potentially exposed in connection with this latest case may develop symptoms through Wednesday, June 17.
Symptoms to watch out for include anything from a fever, a cough, a runny nose, and red, watery eyes that develop into a rash that starts on the face and then spreads to the rest of the body about three to five days after symptoms first start. A person with measles is contagious four days before and four days after the rash appears.
State health official surge people who develop symptoms to call the CDPHE at 720-653-3369 or their local public health agency immediately by phone before trying to seek treatment to avoid other people from becoming potentially infected with the virus. The CDPHE urges people to call an urgent care center or emergency department and explain that you may have been exposed to measles if you do not have a health care provider.
While most people recover within two or three weeks after contracting the virus, unvaccinated people run the risk of complications from the disease, including ear infections, seizures, pneumonia, immune amnesia, brain damage and ultimately, death.
- Denver7 has been closely following confirmed measles cases in Colorado amid a multi-state outbreak in the U.S. that began last year. Explore the map by clicking here or check it out below to see where cases have popped up in 2026:
Measles only spreads from people who show symptoms; it does not spread from people who aren’t feeling sick, state health officials said.
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. If vaccination is not possible, antibody treatment can help in some cases if it’s given within six days of exposure, state health officials said.
“Getting vaccinated is the best way to protect yourself, your family, and your community,” the CDPHE spokesperson said.
People who got vaccinated against measles before 1968 should talk to their health care provider about possibly getting a booster as the vaccine used before that year wasn't as effective.
Colorado well on its way to surpass last year's measles cases
As of Monday, Colorado had reported 23 cases of the virus across 7 counties: Adams (5), Arapahoe (1), Broomfield (4), Delta (1), Lake (6), Saguache (1), and Weld (5), according to statewide data. For context, that's about 64% of all cases the state reported in all of 2025.
The tally is concerning since Colorado had not reached that many number of cases until September of last year. With half a year left to go, it's likely the state will break last year's 36 confirmed measles cases. Up until 2014, Colorado saw between zero and two cases each year.
Across the country, the number of confirmed measles infections so far this year has now surpassed 1,900.
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