Colorado has recorded 16 measles cases in 2025. Here’s how public health officials are responding.

DENVER — Colorado has recorded 16 measles cases in 2025, more than double the total number of cases recorded in the previous 10 years.

State public health officials traced 8 of the 16 cases to a May 13 Turkish Airlines flight into Denver. Seven of the 16 patients who contracted the virus were vaccinated against it. According to Dr. Ned Calonge, chief medical officer at the Colorado Department of Public Health and Environment, four individuals were infected during the flight, while another four contracted the virus at Denver International Airport after being in close proximity to the original infected traveler.

Calonge said all 13 of the 15 cases were travel-related. One person in Archuleta County and one in Denver County contracted the virus after being in close contact with infected people.

“We think we're supported by a high vaccination rate, especially in the metro area, where we've done pretty well,” Calonge said. “I think people with measles are less likely to come into contact with someone who's unvaccinated.”

Denver Health has seen an uptick in those seeking the measles vaccine since May.

“Since the first measles case was diagnosed in Colorado in March, we have observed a significant increase in MMR vaccinations at our Public Health Immunization clinic,” said Dr. Bob Belknap, executive director of the Public Health Institute at Denver Health. “To further safeguard our community and prevent a potential outbreak, our Ambulatory Care Services clinics have proactively reached out to families with unvaccinated children, ensuring they receive the necessary immunizations promptly.”

Belknap also said fever and rash are common symptoms, especially in young children. With greater awareness about measles outbreaks nationally and globally, more patients are expressing concerns about measles. To date, Denver Health has had only one patient who tested positive.

 “We have been preparing as a health care system for the possibility of a local outbreak by developing plans to safely test people as outpatients without exposing others and managing patients with measles or measles exposure during labor and post-partum,” he added.

The first dose of the measles vaccine is 93% effective, and the second is 98% effective at preventing the virus, Calonge said. Colorado’s children have a 94% vaccination rate, which Calonge said is still below the 95% needed to achieve herd immunity. 

Colorado has several school districts where vaccination rates are below 90% among school-aged children, Calonge added. School districts in Montrose, Montezuma, Archuleta, Elbert, Hinsdale, Gunnison, Park, Lake, Costilla, Saguache, Lincoln, Baca and Logan counties all have vaccination rates of lower than 90%. Montezuma, Archuleta and Elbert County have school district rates lower than 80%, according to CDPHE data.

Children over 5 years old, adults over 20, pregnant people and those with weakened immune systems are at the greatest risk for a measles infection that could lead to hospitalization. Symptoms typically appear eight to 12 days after being exposed to the virus and can include high fever, cough, runny nose, sore throat and rash.

Health care providers and laboratories are legally required to report suspected or confirmed measles cases to CDPHE. When the state receives a report, public health officials interview the infected person about when symptoms appeared, where the person went while contagious and who they were in contact with during that time period. Interviewers then reach out to known contacts, work with businesses and health care facilities to notify staff and others who may have been exposed and issue public notices when exposures may have occurred in public spaces, such as Denver International Airport.

People who have received the measles vaccination are advised to monitor for symptoms. Those who are not immune may be eligible for post-exposure prophylaxis, such as a measles vaccine or antibodies if their exposure was recent, Calonge said.  In some cases, people without immunity may be asked to quarantine or stay away from high-risk settings like health care facilities or child care centers to prevent further spread.

“We continue to work with providers, letting them know there's more measles in the environment than they're used to and urging them to stock more vaccines,” Calonge said.

Calonge said he is concerned about further outbreaks across the United States, particularly after Health and Human Services Secretary Robert F. Kennedy Jr, a vaccine skeptic, fired all 17 members of a panel that advises the Centers for Disease Control and Prevention on immunizations. Kennedy has hired eight new staff members to replace the previous panel. 

The American Medical Association said it is concerned about Kennedy’s replacements, who lack the same expertise in vaccinations as their predecessors.

“The AMA is deeply concerned to learn that new members have already been selected for the Advisory Committee on Immunization Practices (ACIP) without transparency and proper vetting to ensure they have the expertise necessary to make vaccine recommendations to protect the health of Americans,” the association wrote in a statement. 

“We urge the Administration to reconsider the removal of the 17 ACIP members who have deep expertise in vaccines so physicians can continue to have confidence in ACIP’s recommendations, which have for decades helped them make recommendations to patients about vaccination,” the statement continued.

The United States has had about 1,200 confirmed measles cases in 2025. Texas, Oklahoma and Kansas have the country’s highest rates of infection.

In April, Kennedy endorsed the MMR vaccine as the “most effective way to prevent the spread of measles,” a position that angered many of his supporters. Later that month, he claimed that the MMR vaccine contains “aborted fetus debris,” which is not true.

Calonge said he is also worried about Kennedy’s picks and his history of anti-vaccine rhetoric.

“We’re concerned that those who have replaced them are not experts in evidence or in vaccines, and some of them are even openly anti-vaccine,” Calonge said. “What we really want to watch is how this new group approaches their work and whether or not it meets the standards for evidence review and recommendations.”