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On April 27, 2026, South Carolina health authorities officially declared the state’s nearly 200-day measles outbreak over. The outbreak infected close to 1,000 people, setting a record for the largest single-state measles outbreak in U.S. history and becoming one of the most significant infectious disease events in recent American history.
According to NBC News, South Carolina health officials formally declared the end of the outbreak after confirming no new cases across multiple consecutive virus transmission cycles. The outbreak began in October 2025, initially with scattered cases in several counties, before rapidly spreading across the state.
Reuters reported that the unprecedented scale of the outbreak was primarily attributed to suboptimal vaccination rates in parts of the state. Measles is a highly contagious disease requiring approximately 95% population vaccination coverage to establish an effective herd immunity barrier. However, measles vaccination rates in some South Carolina communities fell below this threshold.
CNN’s reporting noted that while the outbreak had a severe public health impact, it also unexpectedly drove a significant surge in vaccination rates. During the peak of the outbreak, local health departments launched mass vaccination campaigns, and many previously hesitant parents ultimately chose to vaccinate their children. Research showed that the increase in vaccination rates during the outbreak exceeded the total gains of the previous decade combined.
The New York Times reported that the outbreak placed enormous pressure on South Carolina’s healthcare system. Hundreds of patients required hospitalization, including dozens of children. The outbreak also led to school closures, canceled community events, and a range of other social disruptions, causing significant economic damage to the region.
The U.S. Centers for Disease Control and Prevention (CDC) played a critical role during the outbreak, dispatching expert teams to assist the state government with epidemiological investigations, contact tracing, and vaccination efforts. CDC officials stated that this outbreak once again demonstrated the importance of maintaining high vaccination rates and the critical role of public health infrastructure in responding to infectious disease outbreaks.
Public health experts noted that while South Carolina’s outbreak has ended, the risk of measles across the United States persists. They called on state governments to strengthen vaccination outreach and infrastructure development to prevent similar events from recurring.