Washington health officials have warned that a massive measles outbreak in South Carolina made its way to their state through five separate introductions during a two‑week period in January, according to a study released this week in NEJM Evidence. The five importations resulted in 26 confirmed cases among Washington residents before public health teams contained the spread.
Since the United States declared measles eliminated in 2000, most infections have been linked to travelers returning from countries where the disease remains common, or to unvaccinated Americans who bring the virus back from abroad. However, declining vaccination coverage across the country has turned domestic travel into a more significant threat than overseas trips.
The South Carolina outbreak began on October 2, 2025, and was officially declared over on April 26, 2026. State officials recorded 997 cases, making it the largest measles flare‑up in the nation since the disease was declared eliminated, until it was later overtaken by an ongoing outbreak in Pennsylvania.