Growing pockets of undervaccination contribute to the resurgence and spread of infectious diseases, as shown by an ongoing measles outbreak in northwest Texas, USA. Measles is one of the most contagious diseases known to humans, with a basic reproduction number (R0) of 11–18; this means that—in a completely susceptible, unvaccinated population—an individual with measles typically infects an average of 11–18 other people. Therefore, high levels of immunity in a population (approximately 92·0–94·0%) are necessary to prevent onward transmission. Although the state-level vaccination coverage for the two-dose measles, mumps, and rubella (MMR) vaccine among kindergarteners in Texas was estimated at 94·3% during the 2023–2024 school year, substantial geographical variability exists. Such heterogeneity yields pockets of underimmunisation, thus facilitating ongoing transmission—including the spread from Texas into surrounding states. Here, we use publicly available data from the 2025 northwest Texas outbreak to estimate MMR vaccination coverage in the measles-exposed population. This near real-time estimation allows us to better understand not only current gaps in coverage, but also how coverage has progressed in the early stages of the outbreak. In particular, these estimates provide more up-to-date information on MMR vaccination coverage than traditional coverage surveys of school-aged children, as well as insight into populations beyond this age group—a strength that is especially relevant to the northwest Texas outbreak, given that nearly 60·0% of all outbreak-related cases to date have occurred in children aged under 5 and adults aged over 19.
Abstract:
Publication date:
June 15, 2025
Publication type:
Journal Article