With measles outbreaks in Texas and New Mexico, is it time for Colorado to worry?

The ongoing measles outbreak in Texas and New Mexico is edging closer to Colorado, at least geographically.

Four cases — and possibly a fifth — have been reported in the Texas Panhandle county of Dallam, which sits about 35 miles south of Colorado’s southern border, separated by the Oklahoma Panhandle.

This doesn’t mean an outbreak is imminent in Colorado, of course. But state health officials have been getting ready in case one is.

“Right now we are ensuring that we are prepared,” said Dr. Rachel Herlihy, the state epidemiologist with the Colorado Department of Public Health and Environment. “We know that measles cases can occur at any time. But we know the risk is going to be greater when there are large outbreaks occurring in other parts of the country.”

So what should you be doing now and how worried should you be? The Sun talked to Herlihy and to Dr. Michelle Barron, an infectious disease expert at UCHealth. Here are some answers.

What’s going on with this measles outbreak?

At least 155 cases have been reported in Texas and New Mexico — with 146 of those reported in Texas.

The cases in Texas have been concentrated in children, with 40 occurring in kids under the age of 5, and 70 more in kids ages 5 through 17. One child has died, the first measles death in the United States since 2015.

Of the 146 cases in Texas, five have been in people who were inoculated with at least one dose of a measles vaccine. Of the remaining cases, 79 are in people who are unvaccinated and 62 in people with unknown vaccination status.

The outbreak was initially concentrated in an under-vaccinated Mennonite community in West Texas, but it has since spread outward.

Nationwide, a total of 164 cases of measles have been reported so far in 2025, including the Texas and New Mexico outbreaks. Of those infected, 20% have been hospitalized.

“I want people to fully appreciate that this is a huge outbreak, and we have not seen anything like this in a very long time,” Barron said.

Have there been any infections in Colorado?

There have been no measles infections in Colorado from the current outbreak. (At least as of March 4, 2025, when this story was published.)

The last measles case in a Colorado resident was in 2023. The patient was an adolescent who had traveled abroad.

Travel is a common source of exposure, Barron said, and Colorado often sees a case of measles every year or so related to travel. But you have to go all the way back to the mid-1990s to find the last time there was a locally transmitted case of measles in Colorado, Herlihy said.  

Back up, what is measles? Why is it bad?

People often associate measles with its telltale red rash. But the disease can be much more aggressive than that — attacking the brain and the respiratory system.

Barron said the rash is typically flat and not itchy. Another common symptom are white dots in the mouth called Koplik spots.

The disease can also cause ear infection and diarrhea. Worse, the disease can cause pneumonia or swelling of the brain, which is what can lead to hospitalization and death. Severe complications and deaths are most common in children under 5. 

That’s bad enough, but measles also has a superpower: its contagiousness. The measles virus is among the most contagious ever documented, with one infected person able to pass the disease to as many as 18 other people. The virus is airborne and can linger in the air for as long as two hours after being exhaled by an infected person.

What can people do to prevent measles?

As with all viruses, good hygiene is helpful — wash hands thoroughly, avoid touching your face, wear a tight-fitting mask in settings where you think you could be exposed, etc. But because the virus is so contagious, it can be difficult to avoid it if you are susceptible to infection. So the key, Herlihy said, is to make yourself not susceptible.

“We certainly want to make sure that Coloradans that are working on spring break plans are thinking about vaccine plans ahead of time,” she said.

A two-dose series of the MMR vaccine, which also covers the diseases mumps and rubella, is 97% effective at protecting against measles.

The first dose of MMR vaccine is typically given to kids around their first birthday, but it can be given to kids as young as 6 months old if they will be traveling, especially internationally. (Those kids will still need two doses after they turn 1.) The best advice, Barron and Herlihy said, is to talk to your pediatrician for guidance.

I’ve already had measles or a measles vaccine. Do I need a booster?

The measles vaccine has gone through various formulas and dosing schedules over the years, creating an immunization hodgepodge, depending on when you were born (assuming you got your typical childhood vaccines as a kid).

Here’s what the state advises:

• For people born before 1957, you were likely exposed to measles as a kid. Prior infection is believed to create lifelong immunity for most, so no additional vaccination is recommended.
• For people born before 1968, you may have received an ineffective vaccine, especially if you were born from 1963 through 1967. You should receive a booster dose of the MMR vaccine unless you happen to know that the vaccine you received was a live measles vaccine, and not an inactivated measles vaccine. If you’re unsure, the recommendation is to get the booster.
• For people born from 1968 to 1989, you likely received only one dose of MMR. There is no overall recommendation for these folks to get a booster dose, since one dose of MMR is 93% effective. But Barron said people in this group who didn’t get a second dose later in life may want to get a booster, especially if you live or work around young children.

Herlihy and Barron said there is no known harm in getting a booster if you are unsure of your vaccination status. Again, though, talking it through with your doctor is the best policy.

Does Colorado have a high measles vaccination rate?

Colorado is among the states with the lowest measles vaccination rates in the country for school-age children. That has long been true, but the COVID pandemic — both the lack of access to health care that many families experienced during the pandemic, as well as the rising levels of vaccine skepticism — made it worse.

The percentage of kids in kindergarten through 12th grade who were fully vaccinated against measles in Colorado hit its lowest level last year in at least six years. In the 2023-24 school year, 93.7% of students had received a full course of the MMR vaccine.

That may sound like a lot, but it is below the target level for achieving herd immunity. Because measles is so contagious, health experts say 95% vaccination coverage is needed to ensure the disease can’t spread within a community.

While many districts do hit that mark, there are pockets with measles vaccination coverage below 80%. The state’s immunization dashboard has data by district and by school.

Is it time to worry yet?

Barron said she isn’t trying to cause alarm, but she has been losing sleep as she worries about what could come from the growing outbreak in Texas and New Mexico. That’s why she said it is important for people to know their vaccination status.

“I don’t want to scare people, but I think people should truly be aware,” she said.

While measles has crept closest to Colorado’s southeastern border, Herlihy said she doesn’t see any one area or community more at-risk than another. Measles can just as easily be spread by someone on a plane or driving to the mountains for spring break.

“Really, it’s statewide,” she said of the area she’s watching. “It’s really difficult to predict.”