The United States is facing its worst measles outbreak in more than two decades, with South Carolina's Spartanburg County cluster reaching 920 confirmed cases as of this week, making it the largest single outbreak since the disease was declared eliminated in the country in 2000. The crisis has prompted renewed calls for vaccination and raised serious concerns about whether the nation could lose its measles-free elimination status.
The Centers for Disease Control and Prevention reported 733 confirmed measles cases across 20 states in just the first five weeks of 2026, roughly four times the number the country typically records in an entire year. The Pan American Health Organization issued an epidemiological alert on February 4 citing a 43-fold increase in measles cases in the first three weeks of 2026 compared to the same period in 2025, with 1,031 cases reported across the Americas versus just 23 a year earlier.
Health officials have identified vaccine hesitancy and declining vaccination rates as the primary drivers of the surge. Among confirmed cases with available vaccination data, 78 percent were unvaccinated and 11 percent had unknown vaccination status. More than 700 of the South Carolina cases involved individuals who had not received the recommended two doses of the MMR vaccine.
The outbreak, which began in October 2025, has resulted in at least 18 hospitalizations in South Carolina, though no deaths have been reported. In response to the escalating crisis, MMR vaccinations in Spartanburg County surged 162 percent in January 2026 compared to the previous year, while statewide vaccinations increased by 72 percent. South Carolina has also deployed its Mobile Health Unit to provide free MMR vaccines in affected communities.
A Pan American Health Organization and World Health Organization evaluation team is expected to convene in April 2026 to determine whether the United States will lose its measles elimination status, a designation the country has held since 2000. The potential loss of this status would represent a significant public health setback and could have implications for international travel requirements and disease surveillance efforts. Health authorities have urged all unvaccinated individuals to seek immunization as the outbreak continues to spread across multiple states.
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