Health authorities in South Carolina have officially concluded a devastating measles outbreak that infected 997 individuals across a six-month period, representing the most extensive single-location outbreak since measles elimination was achieved in the United States.
The epidemic started in October 2025 and primarily affected school-aged children who lacked vaccination protection, state health department officials reported.
Officials documented the final infection on March 15, then observed a 42-day waiting period—double the disease’s longest incubation timeframe—before officially announcing the outbreak’s conclusion.
Federal health experts from the Centers for Disease Control and Prevention collaborated with local officials throughout the emergency response, providing data analysis support.
Among all documented infections, 932 individuals had never received measles vaccination. Spartanburg County experienced over 90% of all cases, while students between ages 5 and 17 represented the hardest-hit group with 639 infections.
The health crisis required approximately $2.1 million in state resources and forced 874 students into quarantine measures spanning 33 educational facilities.
Public health leaders noted that outbreak response efforts sparked significant increases in measles immunizations, with over 81,000 vaccine doses distributed throughout the state—representing a 31% jump from 2025 levels.
This outbreak occurred during escalating national measles activity. The CDC documented 2,288 confirmed infections nationwide in 2025, the highest yearly count since 1991, with 1,792 additional cases recorded through April 23 of this year.
Federal authorities declared measles eliminated from American soil in 2000, indicating the virus no longer maintained continuous domestic transmission.
That elimination designation now faces scrutiny, with the Pan American Health Organisation postponing its review decision until November.
