In January 2025, a measles outbreak broke out on the western edge of Texas and soon spread to New Mexico and other states. The overall outbreak would become the largest seen in the country since 2000, when measles was declared eliminated from the US. In Texas, it was the largest outbreak recorded since 1992. And in New Mexico, it was the first measles outbreak seen in the state since 1996.
But the direction of measles cases in the two states diverged. Texas declared an end to the outbreak within its borders on August 18, with 762 cases. In New Mexico, officials declared the outbreak, which began in February, ended on September 26, with a total of 99 cases.
One of the key differences was that in New Mexico, the rapid spread of the highly contagious virus led to a huge increase in measles vaccinations among children and adults, according to a new study. Overall, measles, mumps and rubella (MMR) vaccine shots statewide from January to September increased by 55 percent compared to the same period in 2024.
The study, published in the Centers for Disease Control and Prevention’s Morbidity and Mortality Weekly Report, made the increase in shots even more stark. Over the full year, the number of MMR doses given to children (defined as those under the age of 18) increased by 18 percent compared with 2024 — from 27,988 in 2024 to 32,890 in 2025. Doses among adults (aged 18 and older) increased by a whopping 291 percent – from 5,748 to 22,500 in 2024. 2025.
The increase in vaccinations did not appear to be an unrelated fluke. Within two weeks of the outbreak being declared, the number of vaccine doses administered in all regions of the state began exceeding the number administered during the previous year, health officials said. And in some areas, when the first measles cases were identified, officials saw vaccinations increase as much as 78 and 83 percent week-over-week.
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