US records 4,410 measles cases as outbreak grows

What the report says

The US Centers for Disease Control and Prevention said measles cases in the country have climbed to 4,410 in 2026, up by 330 in one week, alongside 451 hospitalisations nationwide. Al Jazeera reported that children and teenagers account for the largest share of cases, while adults also represent a substantial portion of infections.

The CDC has also sent an investigator to Pennsylvania, where officials are dealing with the country’s largest outbreak. According to the Pennsylvania health department, the state has recorded 1,222 cases across 42 counties, with dozens of new infections added in the latest weekly update. State officials have reported 225 hospitalisations and five confirmed measles-associated deaths, and are still examining a sixth reported death.

Al Jazeera said Pennsylvania has expanded vaccination efforts in affected communities, including pop-up clinics that have delivered thousands of MMR doses since the outbreak began in late April. The federal deployment follows a request for assistance from the state, known as an Epi-Aid.

The broader context is a national decline in measles vaccination among US kindergarteners, which public health officials say leaves more children vulnerable to infection. New York has also responded to rising regional cases by declaring a statewide disaster emergency to make vaccination and testing easier to provide.