The U.S. is grappling with its worst measles resurgence in decades, with cases particularly high in Pennsylvania where over 1,300 cases have been confirmed.
Flu season early rise in England has prompted UK Health Security Agency warnings. Experts urge at-risk groups to get vaccinated before peak transmission.
The CDC is partnering with state epidemiologists to create a standardized definition for measles deaths, ending a period where state health departments made individual determinations.
