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South Carolina health officials announced Monday (April 27) that the United States’ largest measles outbreak in decades has officially ended. The South Carolina Department of Public Health reported that nearly 1,000 people were infected over about six months, with the last new case confirmed on March 17. Officials explained that no new cases have been recorded in more than 42 days, which covers two full measles incubation periods, and marks a complete halt in transmission.
According to the South Carolina Department of Public Health, the outbreak began on October 2, 2025, and was mainly linked to private schools with low vaccination rates. Of the 997 confirmed cases, 639 were children aged five to seventeen, and 264 were under six years old. The vast majority of those infected—932—were unvaccinated, while 20 were partially vaccinated and 26 were fully vaccinated. At least 21 people were hospitalized during the outbreak, but there were no reported deaths. State health officials stated, “There currently are no people in quarantine or isolation. If no new cases are reported, the last day of the outbreak will be April 26.” A 42-day period without new cases is required to officially declare the end of a measles outbreak as it signals a broken transmission chain.
The South Carolina outbreak surpassed previous records, becoming the largest in the United States since measles was declared eliminated in the country over 20 years ago, as reported by the University of Nebraska Medical Center’s Global Center for Health Security. Experts have linked the surge in cases to declining vaccination rates among school-aged children, which dropped from 95% in 2019 to 92% in 2023, according to the Center for Infectious Disease Research & Policy (CIDRAP).
Nationwide, there have been 1,362 confirmed measles cases so far this year, with 94% linked to localized outbreaks. While South Carolina’s outbreak has ended, Utah now has the most active outbreak in the country, with 583 cases and 47 hospitalizations reported as of last week.
Health experts continue to warn about the importance of maintaining high vaccination rates to prevent future outbreaks. Public health agencies are working to boost immunization campaigns and monitor for new cases across the country.