Measles Cases Top 5,000 in U.S. for First Time in 35 Years as Death Toll Rises

The CDC confirmed 5,182 measles infections Friday, the highest annual U.S. total since 1991, with cases reported in 45 states and Washington, D.C. The surge has killed at least eight people, and 96% of cases were among unvaccinated individuals or those with unknown vaccination status, according to federal data.

The discrepancy has become a point of contention, with Pennsylvania confirming six deaths, including one announced Wednesday involving an unvaccinated resident of Jefferson County. New York reported its first measles death in more than three decades on Monday, a child in Lewis County, and Wisconsin reported the death of an infant days later.

State health officials have confirmed eight measles-associated deaths this year, a figure that exceeds the four deaths the CDC has recognized nationwide.

The CDC has not disclosed where its four recognized deaths occurred, a departure from standard reporting practices. The agency is working with an outside group of epidemiologists to establish criteria for classifying measles fatalities, according to federal officials. Pennsylvania’s initial deaths triggered a public dispute between Health and Human Services Secretary Robert F. Kennedy Jr. and Democratic Gov. Josh Shapiro after Kennedy questioned whether the deaths were caused by the virus.

Pennsylvania remains the hardest-hit state, with 1,467 cases recorded since April across 45 counties, according to state records. The outbreak has disproportionately affected undervaccinated Amish and Mennonite communities, and state health officials have intensified vaccination efforts in those areas. Pennsylvania administered more than 100,000 doses of the measles, mumps and rubella vaccine in September and October, according to state data.

New York Gov. Kathy Hochul has issued a state of emergency to expedite vaccine distribution and testing. Federal health officials have allocated $100 million to states for vaccination and contact tracing, though Pennsylvania received a single CDC staffer for data analysis and outbreak forecasting, according to state officials.

The national case count includes 2,132 infections among adults 20 and older, 2,104 among children and teens ages 5 to 19, and 908 among children under 5, according to federal data. At least 562 patients, roughly 11% of all cases, have required hospitalization. Cases have been reported in 45 states and Washington, D.C.; only Arkansas, Hawaii, Mississippi and Nevada have not confirmed an infection.

The surge threatens the United States’ measles elimination status, which the country has held since 2000. The Pan American Health Organization will review transmission data next week to determine whether the designation should be revoked. A country loses elimination status if a single strain of the virus circulates continuously for 12 months. Utah’s outbreak, which has infected more than 700 people, has been circulating since June 2025, likely meeting that threshold.

Measles is among the most contagious viruses known, infecting up to 90% of unvaccinated people exposed to an infected person, according to the CDC. The agency reports that one to three children out of every 1,000 infected will die from complications. Two doses of the MMR vaccine are 97% effective at preventing the disease.

Kennedy, who has a history of vaccine skepticism and founded an anti-vaccine organization, has expressed doubt about the MMR shot and promoted unproven treatments. He and President Donald Trump have pursued policy changes affecting vaccine regulation, including an August executive order proposing to split the combined MMR immunization into three separate shots, a change that would be costly and time-consuming for manufacturers Merck & Co. and GSK Plc.

The current outbreak has accelerated as vaccination rates have declined, weakening the herd immunity that typically suppresses transmission and protects individuals who cannot be immunized for medical reasons, according to public health officials.