The deadly outbreak in Pennsylvania is its largest in more than three decades, and confirmed cases in New York are up

The New York governor, Kathy Hochul, declared a state of emergency on Monday in response to a dramatic spike in measles cases in the state.

Hochul’s administration said the emergency declaration was in response to a “growing number of measles cases across rural areas of New York and neighboring states”, including Pennsylvania, which has been grappling with a deadly outbreak that is its largest in more than three decades.