Texas measles outbreak could be halved with 5% vaccination increase, study finds
UT Austin researchers model three vaccination scenarios, showing how small changes in MMR uptake could dramatically affect cases and hospitalizations in Texas
A Texas measles outbreak could have been roughly half as severe if MMR vaccination rates had been five percentage points higher, according to a letter in JAMA by researchers from the University of Texas at Austin. The study modeled the 2025 Texas outbreak across three vaccination scenarios—current uptake, five percent higher, and five percent lower—to estimate how changes in immunization would alter cases and hospitalizations. The first case in the simulated outbreak appeared January 20, 2025, in Gaines County, and the model ran through June 10, 2025. In real life, the Texas outbreak sickened 762 people and led to 99 hospitalizations, including the deaths of two young girls.
Gaines County was the epicenter, with vaccination coverage lower than the state average. Texas kindergarten vaccination rates had declined to 94.3 percent, down from 98.5 percent in 2013. In Gaines County specifically, coverage was about 82 percent. Under current vaccination levels, the model estimated about 400 infections and roughly 80 hospitalizations in Gaines County alone. A scenario with five percent fewer vaccinated would bring about 500 cases and about 100 hospitalizations in the county, while a five percent increase would drop cases to about 200 and hospitalizations to about 40. Across Texas, the study projected that six counties would have infection rates above 12 cases per 1,000 people under current rates; with five percent higher vaccination, the model suggested no county would exceed that threshold.
For the broader state, the researchers noted that the total numbers were not reported. The letter in JAMA describes a computer model of Texas that simulated the three vaccination-rate scenarios and tracked how outbreaks might unfold. In all three runs, the first measles case was detected in Gaines County, mirroring the recent outbreak, and the simulations extended through early June 2025.
The research team warned that improving MMR vaccination coverage is essential to prevent large-scale outbreaks, especially in regions where immunization has slipped. They highlighted the ongoing challenges of maintaining community immunity amid vaccine hesitancy and disruptions to routine vaccination programs.
The study appears as policy discussions around measles vaccines intensify. Proposals from Robert F. Kennedy Jr.’s team have called for tweaking U.S. measles vaccination recommendations. Nationally, about 92.5 percent of kindergarteners are reported vaccinated against measles, down from a peak of roughly 95.2 percent in 2019-2020. The CDC still recommends 95 percent vaccination for herd immunity. The new analysis used three scenarios to illustrate how modest changes in uptake could alter outcomes for a major outbreak.
Citing historical context, the piece notes that measles once affected millions in the United States annually, with tens of thousands hospitalized and hundreds of deaths, before vaccination programs reduced incidence. While the United States achieved measles elimination status in 2000, outbreaks have re-emerged in pockets where vaccination has declined, including in parts of Texas this year. The year’s Texas outbreak had 1,491 reported measles cases—the most since elimination—highlighting the ongoing risk posed by gaps in immunization.
Measles is among the most contagious diseases. An unvaccinated person infected with measles can readily transmit the virus to a large portion of susceptible people, with estimates suggesting that a single case can infect about nine of every ten unvaccinated individuals contacted. Early symptoms commonly include fever, cough, runny nose, and red eyes, followed by a distinctive reddish-brown rash within days. The virus is especially dangerous for older adults, young children, and pregnant women, and complications can include pneumonia, encephalitis, and hospitalization. The CDC notes that among unvaccinated children who are infected, hospitalization occurs in roughly one in five, and serious complications, though less common, can be severe.
Public health officials stress the importance of maintaining routine vaccination programs even amid hesitancy. The Texas experience has underscored how local disparities—such as lower coverage in smaller counties with specific communities—can amplify risk and drive outbreaks, even as national vaccination rates trend downward.