A Rapid Risk Assessment for Measles Outbreaks in North Carolina

BackgroundOn June 24, 2025, the North Carolina Department of Health and Human Services (NCDHHS) announced a measles case from an international traveler which resulted in multiple exposures including attendance at the Greensboro Science Center, which hosts over 621,000 visitors annually. Given declining measles vaccination rates across the US and ongoing national outbreaks, we estimated potential secondary cases that might occur if measles were introduced into different elementary schools in North Carolina. MethodsWe used kindergarten immunization data from NCDHHS (2019-2023) to estimate potential secondary cases using a Susceptible, Exposed, Infected, Recovered, Vaccinated (SEIRV) model. We then estimated the marginal impact of vaccination on outbreak risk. ResultsOnly 47 of North Carolinas 100 counties have the recommended full vaccination rates of at least 95%. We found that over 41,000 out of over 641,000 (6.5%) elementary-aged students have not been fully vaccinated against the measles. Of the 1,474 elementary schools we considered, 142 elementary schools have a greater than 50% probability of at least 10 cases should measles be introduced; 28 schools have probabilities exceeding 80%. LimitationsWe assume that the SEIRV framework adequately captures the dynamics of students within a school with homogeneous mixing. ConclusionsMeasles vaccination coverage in North Carolina has decreased, leaving many children at risk for infection. Many schools have vaccination levels low enough to cause large, sustained outbreaks if a single measles case were introduced. By providing these approximate, order-of-magnitude estimates to public health officials, they can adequately plan for outbreak response and prioritize school and communities at risk for vaccination campaigns.