A new modelling study warns that repealing Florida’s school measles vaccination mandate could trigger the largest measles epidemic in the United States in nearly 50 years. The University of Maryland-led study, published in the Proceedings of the National Academy of Sciences on 28 September 2026, modelled the effects of dropping the MMR requirement for schoolchildren.

The model used data from the 2025 Gaines County, Texas outbreak along with Florida demographics, MMR coverage rates and mixing patterns. Researchers found that without the mandate, falling vaccination coverage would create the conditions for a major outbreak.

Health officials and paediatricians have already voiced concern about rising measles cases in Florida and across the country. The findings add scientific weight to the debate over vaccine mandates, which has intensified as some states move to loosen school immunisation requirements. Public health experts said the study underscores how quickly measles can return when community protection falls below safe thresholds.