DENVER — A fifth person in Weld County has tested positive for measles, state health officials said Tuesday, warning Coloradans could have been exposed to the highly transmissible virus at two health care centers in Larimer County this week.
The latest case was confirmed in an unvaccinated adult who is a close contact of previous cases within the county, according to a Colorado Department of Public Health and Environment spokesperson. The patient — along with three other previous cases reported by the CDPHE over the past several weeks — is not believed to be tied to an ongoing outbreak in Broomfield.
State health official said this latest patient could have exposed people at the UCHealth Primary Care clinic in Johnstown, located at 4846 Larimer Parkway on Monday, April 13, between 3:15 p.m. – 5:20 p.m.; and at the Banner Fort Collins Medical Center Emergency, located at 4700 Lady Moon Drive, between 3:35 p.m. and 6:10 p.m. on that same date.
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 Monday, May 4.
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.
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, 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.
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.
Another bad measles year likely on the horizon for Colorado
As of Tuesday, Colorado has reported cases of the virus in Adams (5), Arapahoe (1), Broomfield (4), Saguache (1), and Weld (5) counties, according to statewide data.
Weld County is now tied with Adams County when it comes to the greatest number of cases so far this year. More concerning, however, is that with this latest Weld County case, the state’s measles tally now stands at 16 — a number that Colorado did not reach until late July last year, which suggests that the state is in for another rough measles year in 2026.
Last year, amid a multi-state outbreak of the virus across the country, Colorado reported 36 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 1,700, which represents about 75% of all measles cases the U.S. reported in all of 2025.
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