Colorado health officials remain optimistic about state’s measles preparedness despite new case in Denver

Colorado reported a new case of measles Wednesday, the fourth one confirmed in the state this year.

But the state’s top doctor earlier in the week expressed optimism about the overall measles situation in Colorado, noting that all the cases so far appear to have fizzled out, vaccinations are increasing and health care providers are more alert to the possibility of seeing an infection.

The new case was identified in Denver. The person is described as a “household contact” of an earlier Denver case, one in a baby who had recently traveled with family to Mexico. In the new case, the infected person had been in quarantine during their infectious period.

As a result, the Denver Department of Public Health and Environment said it does not believe there was any risk of exposure to the general public from the new infection.

The two Denver cases add to one from Pueblo and another from Archuleta County in southwestern Colorado so far in 2025.

No ongoing outbreaks

In an interview Tuesday, Dr. Ned Calonge, the chief medical officer at the Colorado Department of Public Health and Environment, said the cases in Pueblo and in Archuleta County are beyond the incubation period where officials would worry they could turn into sustained outbreaks.

“I’m going to knock on wood,” he said.

The infection in Archuleta County did technically create an outbreak — the county health department announced last week that measles cases diagnosed out of state have been linked back to the Archuleta case. Wolf Creek ski area is among the places where people may have been exposed in the incident.

But the Archuleta case does not appear to have led to any additional infections in Colorado, and the new Denver case is the only known instance of the virus spreading between Coloradans within the state.

Urging earlier notification

Calonge said the state has worked with hospitals, health clinics and labs to identify and report suspected measles cases faster.

It took nine days in Pueblo between when the infected person was seen at a clinic and when the positive measles test result was reported to the state. The interval was smaller in Archuleta County. But in both cases, by the time health officials told the public about the cases and began contact tracing, enough time had elapsed that any newly infected people could have already been spreading the virus to others.

Calonge said the state has issued several alerts to medical providers and labs, telling them to be on the lookout for measles and reminding them they are required to report suspected cases immediately.

“We have the attention of the provider community, and we’re hoping that the delays won’t occur any more,” Calonge said.

Collaboration with local, federal agencies

Calonge said CDPHE is working closely with local public health agencies to prepare for potential measles cases — something he described as a legacy of the state’s response to COVID-19.

While things are relatively calm here, measles outbreaks continue to rage nationwide, especially in states near Colorado. More than 800 infections have been reported this year in the United States, including more than 600 in Texas. New Mexico is up to 65 confirmed cases, while Kansas has identified 37 cases, mostly in the southwestern part of the state.

Calonge said collaboration with the federal Centers for Disease Control and Prevention has also been good.

How well the CDC will be able to contribute to states’ efforts has been a concern among public health advocates nationwide, following cuts to funding as well as other dramatic changes ushered in when Robert F. Kennedy Jr., a prominent critic of the measles vaccine, took over the U.S. Department of Health and Human Services.

During a meeting last week, a senior CDC scientist said the agency believes measles cases have been underreported and that recent funding cuts have hurt the response.

Calonge said Colorado has seen no problems.

“We’ve been very well supported by the CDC,” he said.

Increasing vaccinations

Meanwhile, vaccinations against measles appear to be rising.

As of last week, the state had seen a 45% year-over-year increase in the number of doses of MMR vaccine given to infants. (One dose of MMR vaccine is typically given at 12 months of age, with a second dose given around age 5.)

Adults have also been seeking out vaccination, Calonge said. Two doses of MMR are considered 97% effective at preventing measles infection, and older adults who were exposed to measles as a child are considered to have lifelong immunity.

But some adults may have received a less effective vaccine in their youth, while others may have received only one dose. This has led some adults nationwide to get a booster shot, and Colorado appears to be seeing the trend as well.

Calonge said Colorado has seen a 126% year-over-year increase in the number of doses of MMR vaccine given to adults in 2025.

Despite the uptick, Calonge said MMR vaccine supplies remain plentiful. People considering vaccination or with questions should talk to their doctor, he said.

Getting vaccinated is considered the most effective step you can take to prevent measles infection. And, while Colorado does have pockets with lower-than-average vaccination rates, he said the state in general has high levels of immunity.

For that reason, he said potential measles outbreaks here are not like what the state was facing at the beginning of the COVID pandemic. Large numbers of people are not projected to get sick all at once. Hospital capacity is not expected to be strained.

“We’re already starting with a much higher level of immunity in most communities,” he said. “So the susceptible populations are much smaller.”