As of Aug. 5, 2025, the U.S. has reported 1356 measles cases, the largest number of cases since elimination was declared in 2000. Most of these cases have occurred in Texas. In response to the growing Texas outbreak, the Centers for Disease Control and Prevention (CDC) issued updated guidelines through the Health Alert Network (HAN) on March 7, 2025, recommending early vaccination (ages 6 to 11 months) for children living in or traveling to affected counties. This analysis by Goodwin Cartwright, et al. (2025) examined whether children in Texas received early measles vaccination following the HAN and assessed shifts in age-related vaccination patterns.

The authors identified infants residing in Texas within Truveta Data who had outpatient encounters at 2 to 4, 4 to 6, and 6 to 11 months of age between 2019 and April 2025 (henceforth referred to as regular care). Truveta Data consists of electronic health records provided by member U.S. healthcare systems that have been deidentified by expert determination in accordance with the HIPAA Privacy Rule. They identified MMR or MMRV vaccines administered between 182 days and 24 months of age. They then conducted 2 analyses. First, for each calendar month, we calculated the proportion of measles vaccinations administered early (between 6 to 11 months of age) among children with regular care. Second, they calculated the proportion of children with regular care who were vaccinated, by age in months (6 to 11 months) from January 2024 to April 2025.

This study included 82,949 children in Texas receiving regular care (40,322 female [48.6%]; 25,085 Hispanic or Latino ethnicity [30.2%]; 3591 Asian [4.3%], 10 379 Black [12.5%], 52,961 White [63.8%] race); 66,749 children (80.5%) received at least 1 measles vaccine before age 2 years. Among children who received their first measles vaccine by 24 months of age, we observed a sharp rise in the proportion receiving early vaccination (ages 6 to 11 months) beginning in February 2025. In March and April, 422 of 2094 first doses (20.1%) were given early. The proportion of early vaccination remained at 0.7% (332 early doses of 48, 453 total) from 2020 through January 2025. During 2019, the proportion of children receiving early vaccination was also higher (153 of 8,781 doses [1.7%]), when a different outbreak prompted similar recommendations, but the March-April 2025 rate was 11.5-fold higher.

From January 2024 to January 2025 (baseline, preoutbreak period), monthly vaccination rates for all age groups were below 2%. In April 2025, rates peaked at 10.0% for 10-month-olds (a 10.4-fold increase from baseline). Six-month-olds also had high rates at 8.7%; a 31.7-fold increase from baseline (0.3%). In April 2025, vaccination rates were lowest among children ages 11 and 8 months.

Reference: Goodwin Cartwright BM, et al. Early MMR Vaccine Adoption During the 2025 Texas Measles Outbreak. JAMA Netw Open. 2025;8;(11):e2543002. doi:10.1001/jamanetworkopen.2025.43002