The United States has recorded 4,410 measles cases so far in 2026, an increase of 330 in one week, according to the Centers for Disease Control and Prevention. The agency has counted 451 measles-related hospitalizations nationwide and sent an investigator to Pennsylvania to assist with the country’s largest outbreak.
Pennsylvania had reported 1,222 cases across 42 counties as of Wednesday, including 86 new infections since October 9. The state has recorded 225 hospitalizations and five confirmed deaths associated with measles. Officials are investigating a sixth reported death.
The federal response followed a request from Pennsylvania. State health teams have administered more than 5,900 measles, mumps and rubella vaccine doses at 202 pop-up clinics since the outbreak began in late April. Children and teenagers aged five to 19 account for 42 percent of US cases this year, while adults aged 20 and older make up 41 percent.
National kindergarten vaccination coverage has declined from 95.2 percent in the 2019–2020 school year to 92.4 percent in 2025–2026. The CDC estimates that about 280,000 kindergarten-age children are at risk because of gaps in coverage, underscoring the role of vaccination in limiting further spread.
