Assessing MMR vaccination coverage gaps in US children with digital participatory surveillance

Recent measles outbreaks in the USA have emerged despite the availability of the highly effective measles–mumps–rubella (MMR) vaccine. Current surveillance systems rely primarily on telephone surveys with provider verification or school-entry data, methods prone to incompleteness and systematic exclusion of vulnerable populations. Here, to address these limitations, we used a validated digital participatory surveillance platform to collect parental reports of ≥1-dose MMR vaccination among children under 5 years of age. Applying Small Area Estimation methods to generate granular, county-level coverage estimates nationwide, we found substantial geographic variation, including areas with MMR coverage <60%. Analysis of spatial clustering revealed hotspots of undervaccination overlapping closely with recent measles outbreaks, particularly in Texas and New Mexico—where our model estimates substantially lower vaccine coverage than official data. These findings underscore the urgent need for surveillance systems to include more granular and timely data that accurately identify undervaccinated communities, enabling targeted, timely public health interventions. Digital surveillance at the national scale, coupled with a spatial model that extends the data to a more granular scale, reveals gaps in MMR vaccination coverage that align with recent measles outbreaks.