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The United States is currently experiencing its worst year for measles cases since 1991, according to data from the U.S. The milestone marks a generational setback in controlling the highly contagious viral disease, which was declared eliminated nationwide in 2000 after a lack of continuous spread for over a year.
Nationwide, the CDC has reported 2,318 measles cases so far this year. The total surpasses any annual count recorded since a major nationwide epidemic between 1989 and 1991, which resulted in 55,365 cases across three years, including 9,643 cases in 1991 alone.
“Halfway into 2026 the U.S. is experiencing the worst year for measles since 1991. We are witnessing an avoidable crisis that disproportionally hurts children,” Dr. Andrew Racine, president of the American Academy of Pediatrics, said in a statement. “These thousands of cases represent real people in communities across the country, including babies hospitalized with pneumonia.”
Vaccination Rates and Demographic Impact
The resurgence aligns with declining national vaccination rates, which have fallen below the 95% threshold required to prevent widespread community outbreaks. Data from the CDC show that during the 2024-25 school year, 92.5% of kindergartners received the measles vaccine, down from 95.2% during the 2019-20 school year. More than half of U.S. states recorded drops in kindergarten vaccination coverage compared to the prior year.
California continues to maintain an overall kindergarten vaccination rate above the target threshold at 96.1% for the 2024-25 school year. However, several local jurisdictions fall short of the goal. Southern California counties San Diego and San Bernardino report vaccination rates of 93.7%, while Kern County reports 89.3%. Other counties below the 95% threshold include Calaveras, Del Norte, El Dorado, Glenn, Humboldt, Nevada, Santa Cruz, Shasta, Sierra, Sutter, and Tuolumne.
Demographically, the CDC reports that 93% of this year’s measles cases occurred among individuals who were unvaccinated or whose vaccination status was unknown. Children under the age of 5 account for 20% of infections, while individuals aged 5 to 19 represent 49% of cases. More than 150 patients have required hospitalization nationwide.
Several localized outbreaks have driven transmission in California this year, including a three-person family cluster in Riverside County, a nine-person outbreak among a church group in Shasta County, and additional spread spanning Sacramento and Placer counties.
Federal Context and Public Health Debate
Kennedy has maintained that he is not anti-vaccine.
Critics, including lawmakers and medical organizations, argue that skeptical messaging from federal figures undermines public health efforts. Rep. Linda T. Sanchez told Kennedy during a House committee hearing that anti-vaccine rhetoric correlates directly with surges in preventable illnesses. Concurrently, the American Academy of Pediatrics has criticized federal leadership for characterizing measles as benign and for disseminating misleading information regarding the MMR vaccine.
“Today, I want to remind parents that measles is not just a rash,” Racine said. “The virus can interrupt the immune system’s memory, leaving a previously healthy child significantly more likely to get sick from any type of infection.”
Health officials warn that if current transmission trends persist, the United States will officially lose its measles elimination status, following Canada, which lost its status the previous year. According to the World Health Organization, Mexico currently ranks among the top ten countries globally experiencing measles outbreaks.
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