Whole-Genome Sequencing of Measles Virus from 2025 Outbreak, Texas, USA

In 2025, Texas experienced its largest measles outbreak since elimination in 2000, with 762 confirmed cases, more than half occurring in Gaines County. Researchers sequenced 368 measles virus genomes from 491 samples and identified expansion of a closely related genotype D8 lineage within broader strain diversity in North America. Among 359 individuals with available vaccination data, 204 persons (56.8%) were unvaccinated and 139 persons (38.7%) had unknown vaccination status. Phylogenetic analysis revealed that Texas virus genomes formed a closely related strain with a median of 3 differences in individual nucleotides. The study demonstrates that whole-genome sequencing can strengthen measles surveillance and improve outbreak investigations.