The Centers for Disease Control and Prevention confirmed six measles-related deaths in the United States this year, marking the worst resurgence of the disease in 35 years.

The update, posted on the agency's website Thursday, doubles the death toll recorded in 2025. Measles cases have exceeded 5,000 for the first time since 1991, with 5,182 confirmed infections reported as of November 5. The vast majority of cases involved individuals who were unvaccinated or whose vaccination status was unknown.

Pennsylvania remains the hardest-hit state, with 1,487 cases and six measles-associated deaths confirmed by state officials this year. Additional fatalities include a child in New York, the state's first known measles death in more than 30 years, and an infant in Wisconsin, the first there since 1990.

The CDC switched its tracking method to National Center for Health Statistics mortality data under Health Secretary Robert F. Kennedy Jr., which accounts for differences between federal and state-reported figures. Nationwide, 11 percent of cases required hospitalization.

The outbreak has prompted concerns that the United States may lose its measles elimination status, declared in 2000, with a Pan American Health Organization review expected soon. Active cases span nearly every state, underscoring gaps in vaccination coverage that have allowed the highly contagious virus to spread.

Two doses of the MMR vaccine provide 97 percent effectiveness against measles. Public health officials continue to emphasize vaccination as the primary defense amid the ongoing surge.