Measles Vaccine Uptake During the 2025 Texas Measles Outbreak in a San Antonio Military Medical Center

Abstract Objective To evaluate changes in measles-containing vaccine (MCV) uptake, inclusive of MMR and MMRV, by age group and over time during the 2025 Texas measles outbreak. Methods We conducted a retrospective, single-center, observational study comparing January through August 2024 (pre-outbreak) with the same period in 2025 (outbreak) at a military medical center in San Antonio, TX. The study evaluated MCVs administered and recorded in the electronic health record (EHR) to all patients from 0-18 years enrolled during these periods. The primary outcome was the MCV administration rate (doses per 1,000 child-months). Based on this, we estimated incidence rate ratios (IRR) with 95% confidence intervals (CIs) comparing 2025 vs 2024 overall and by age groups. Results MCV administration increased from 10.82 per 1,000 child-months in 2024 to 13.22 per 1,000 child-months in 2025, across all age groups (IRR 1.22; 95% CI, 1.11–1.34; p<0.001). This increase was driven by early-dose vaccination in infants aged 6-11 months (IRR 21.09; 95% CI, 9.89–44.98) and children aged 24-47 months (IRR 4.73; 95% CI, 2.84–7.87). MCV administration rates did not clearly differ among children 12-23 months (IRR 1.08; 95% CI, 0.94–1.24), 4-5 years (IRR 1.07; 95% CI, 0.93–1.23), or 6-18 years (IRR 0.54; 95% CI, 0.28–1.06). Peak vaccine uptake occurred early in the outbreak and then declined toward baseline. Conclusions At a military medical center in San Antonio, the 2025 Texas measles outbreak was associated with an early transient increase in MCV uptake principally driven by early infant vaccination, and by late summer, the uptake returned toward baseline.