More than 5,000 measles cases have been reported in the United States this year, the highest annual total in 35 years, according to new data from the Centers for Disease Control and Prevention (CDC).

The CDC has confirmed 5,182 cases in 2026 so far, the highest number since 1991. The figure is more than double the 2,289 cases recorded in all of 2025. The vast majority, 4,993 cases, are linked to outbreaks.

Children and teenagers account for nearly 60 per cent of confirmed cases. Children under five make up 18 per cent, while those aged five to 19 account for 41 per cent. Measles was declared eliminated in the United States in 2000, but vaccination coverage among kindergarteners has fallen from 95.2 per cent in the 2019-2020 school year to 92.4 per cent in 2025-2026.

Death toll disputed

The CDC lists four measles deaths in 2026. State health departments have reported more, and the gap has become a public dispute. Pennsylvania, the worst-hit state, reports 1,487 cases and six deaths this year.

Pennsylvania counts a death as "measles-associated" when a person with confirmed measles dies within 30 days of symptoms appearing, unless the death was clearly unrelated. The CDC initially counted two unvaccinated Pennsylvanians who died in August, then removed them after Health Secretary Robert F. Kennedy Jr questioned whether measles caused the deaths. Pennsylvania Governor Josh Shapiro has challenged that decision.

The CDC says it is working with the Council of State and Territorial Epidemiologists to agree a standard definition for a measles death. Health experts warn that falling vaccination rates leave communities vulnerable to a disease that, before the vaccine arrived in 1963, killed an estimated 400 to 500 Americans a year.