The latest on the 2025 Texas outbreak
The measles outbreak in Texas is growing fast, up to 146 cases as of last Friday. The 56 measles cases reported in the last week alone qualify it as a ‘large’ outbreak in the post-elimination era in the US.
Tragically, an unvaccinated child died of measles last week, the first measles death in the US in a decade. This rattled me personally – since I started studying measles during my PhD in 2016, there had been no deaths in the US. And this preventable death should have rattled HHS leadership, but RFK Jr. instead just shared an alarming amount of disinformation:
- He said “it’s not unusual” to have measles outbreaks, downplaying this outbreak’s rapid growth and the concerning reality that outbreaks are increasing in frequency;
- He said most patients in Texas had been hospitalized for quarantine, while Texas health officials refuted this claim: they confirmed the patients were hospitalized “because they were having trouble breathing”;
- RFK Jr. has also long promoted Vitamin A as a measles treatment (Vitamin A deficiency has been shown to correlate with severe disease, particularly in developing nations with high rates of malnutrition). This is something to watch, and could signal real danger if he begins to promote Vitamin A as an alternative to measles vaccination.
This outbreak has primarily affected Gaines County, TX. As of February 28, Gaines County has reported 98 measles cases. The county has poor pediatric vaccination rates, with only 82% MMR coverage in kindergarteners. Cases are much lower in nearby TX counties with higher vaccination status (like Lubbock County, with only 2 cases). Cases are likely to continue to climb in Gaines, with many unvaccinated children and many infectious cases.
Right across the border in Lea County, NM, there have only been 9 cases of measles. Vaccination coverage there is much higher, at 94% of children aged 0-18. It’s possible a large outbreak in New Mexico won’t develop due to this high vaccination coverage.
To better understand this spatially patterned outbreak, I want to discuss a measles outbreak that happened 55 years ago, also in Texas. This cautionary example paints a picture of what may lie in store if vaccine denial continues at its current pace, or worsens.
A 1970 measles outbreak in Texarkana, a city on the Texas/Arkansas border, still resonates today
The live attenuated measles vaccine, a modern medical marvel, had been out for 7 years. It was licensed in 1963. Everyone knew about measles in the US: 42,043 cases were reported in 1970.
In 1970, Texarkana had a population of 50,000 people. The city, bisected by the TX/AR state line, had Bowie County on the Texas side and Miller county on the AR side. While residents of the two sides of Texarkana frequented the same businesses, stores, restaurants, and churches, they had separate public schools and public health departments. These different public health departments and school systems resulted in different vaccination requirements and measles vaccine campaigns on the two sides of the city:
- On the Bowie County (TX) side of Texarkana, there had never been a mass vaccination campaign for measles. An estimated 18.8% of children 1-9 years old received the measles vaccine. There was also no vaccine requirement for children entering school. Estimated total immunity from either vaccination or history of disease in this age group was 57%.
- On the Miller County (AR) side, there was a state immunization requirement for measles vaccine for school children, and large-scale mass vaccination campaigns had been conducted. An estimated 70.5% of children 1-9 years old received a vaccine. The estimated total level of immunity was > 95%.
Amid this split-city context, 633 cases of measles spread through the city from June 1970 – Jan 1971 (See this amazing epi curve from the JAMA paper describing the outbreak)
Without reading ahead, you might surmise that the outbreak did not play out the same way on both sides of the city. In fact, the discrepancy was dramatic: 606 cases (95.7%) occurred on the TX side of the border, and only 27 cases occurred in AR.
This outbreak was a perfect natural experiment for vaccine effectiveness. Children on the TX side of the border were far more likely to contract measles, even though all Texarkana residents had many common exposures. You can see the density of measles cases from this epidemiologic outbreak map.
The outbreak also allowed for a vaccine effectiveness survey as 27 children (4%) had a history of prior vaccination with the live attenuated measles vaccine. The attack rate among previously vaccinated children aged 1-9 years was 4.3/1000 while the attack rate among unvaccinated children was 105.9/1000 – more than 26 times higher. This translated to a vaccine effectiveness of 95.9%.
Philip Landrigan, the study’s author, summarizes the results best: “The major point illustrated by this outbreak is that [the] measles vaccine protected children against measles. The spread of measles in this epidemic did not result from vaccine failure, but from inadequate use of vaccine…The common factor in both areas was, however, that disease spread in unvaccinated children grouped together.”
What does this all mean in 2025?
We won’t see uniform, homogeneous spread of measles across the Southwest (or the US as a whole) because risk is not random. As the Texarkana example showed us, measles outbreaks happen where vaccination coverage is low, and where “unvaccinated children [are] grouped together.” When vaccination campaigns are rolled out, uptake is not homogeneous either, with certain communities less likely to take the vaccine, further reinforcing these patterns.
If vaccine denial and hesitancy continue to rise, aided by an anti-vaccine spokesperson at the highest level of government, state legislatures, in turn, may begin to repeal vaccine requirements for school entry. States already have different policies regarding vaccine exemptions, with all states allowing medical exemptions, but some allowing religious and/or philosophical exemptions as well.
This has already created a patchwork of vaccination coverage rates by state, but the disparities could become much more dramatic if some states remove school requirements altogether. That could lead to more situations like the one in Texarkana, where the laws/policies of the state where you live put you and your family at different levels of risk of contracting vaccine-preventable diseases.
Republican officials have also recently introduced bills to either loosen vaccine requirements or remove them all together:
- A newly introduced bill in AZ would make it easier to get school vaccine exemptions
- Bills in CT, MN, NY, and OR would limit or prohibit any vaccine mandates for adults (many of these are focused on the COVID-19 vaccine)
- An ID bill was introduced to ban mRNA vaccines for 10 years, and similar bills were recently defeated in MT and MS
- WV, which currently only allows medical vaccine exemptions, is advancing a bill to allow religious and philosophical exemptions.
So what can you do?
If you live in one of these states, call your state reps. Let them know that vaccines save lives, and school requirements protect our communities. Continue to monitor local news to keep track of anti-vaccine legislation. Join your school board, PTA, or get activated in your local community to have a voice at meetings where vaccine decisions and policies are discussed.
Know Your Vax 
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