A major measles outbreak in South Carolina is showing signs of slowing, with new weekly cases dropping to around 10 from a peak of 200 in mid-January. However, it remains the largest U.S. outbreak in over 30 years, with low vaccination rates and holiday gatherings having fueled its spread, primarily among unvaccinated children.
The ongoing national case count now risks the United States losing its measles elimination status. Health officials are cautiously optimistic but warn that spring break travel could lead to another surge in infections.
The outbreak has spurred a significant increase in MMR vaccinations both in the epicenter of Spartanburg County and across the state.
Main Topics: The South Carolina measles outbreak's current status and trends; the national context and risk to measles elimination status; causes and characteristics of the outbreak; public health response and vaccination efforts.
A large measles outbreak in South Carolina is finally showing signs of slowing down as the total number of cases in the state nears 1,000.
For several weeks now, the state has experienced a downward trend in new infections, with approximately 10 cases being reported per week. At its peak in mid-January, the state was reporting around 200 new cases a week.
The South Carolina outbreak is the largest measles outbreak in the US in more than 30 years, according to data from the Centers for Disease Control and Prevention. The CDC has confirmed 1,281 measles cases across the country this year, as of March 5. That is already more than half of the documented cases in 2025, which totaled 2,283.
Measles was declared eliminated in the US in 2000, a status attained when there has been no ongoing transmission within the country for longer than a year. Even with cases in South Carolina abating, the US is now at risk of losing its measles elimination status. According to the CDC, there have been 12 outbreaks in the US this year, including ones in Arizona, Texas, and Utah.
Linda Bell, South Carolina’s state epidemiologist, is encouraged by the decrease in new cases in her state, though she notes that with schools going on spring break in March and April, there is a potential for more exposures as families travel and visit tourist attractions.
“We remain concerned and must be mindful of the fact that we can see cases increase again from the low number that we're seeing now,” she said in a March 4 press briefing. “We are very hopeful that the downward trend continues, but we have to be vigilant about the risk that we can see another surge.”
The outbreak began with just a handful of cases in October and has centered in Spartanburg County. Low vaccination rates in schools helped spread the virus, with social events around the winter holidays fueling a surge of cases in January. Churches have also been a major source of exposure, according to Bell.
Measles symptoms, which include high fever, cough, runny nose, and watery eyes, typically don’t appear until one to two weeks after exposure. The characteristic measles rash takes another several days to develop, which contributes to a lag in diagnosing the infection. Measles can cause severe complications, such as pneumonia and brain swelling, both of which have been documented in South Carolina. More than 93 percent of the cases in South Carolina have occurred in people who were unvaccinated. The vast majority of infections have been in children under 18.
Bell said that modeling from earlier in the outbreak showed that South Carolina’s outbreak could go on for six months or longer. Now, it may end sooner than predicted.
The outbreak has prompted an uptick in vaccination with the measles, mumps, and rubella (MMR) vaccine in Spartanburg County and across the state. Compared to February 2025, there was a 133 percent increase in measles vaccination in Spartanburg County, representing roughly 900 additional doses given, according to the South Carolina Department of Public Health. An additional 7,000 doses of measles vaccinations were administered statewide in February, a 70 percent increase from the same time last year.
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