South Carolina Measles Outbreak Shows Signs of Slowing, But Elimination Status at Risk

The United States is witnessing a significant public health development as the largest measles outbreak in over three decades shows promising signs of abating. What began as a handful of cases in South Carolina last October has grown into a national concern, with the Centers for Disease Control and Prevention (CDC) confirming 1,281 measles cases across the country as of March 5. This already exceeds half of the total documented cases for all of 2025, which numbered 2,283. The outbreak's epicenter in Spartanburg County, South Carolina, has driven much of this surge, but recent data indicates a substantial decline in new infections.

Outbreak Trajectory and Current Status

For several weeks, South Carolina has experienced a consistent downward trend in new measles infections. The state is now reporting approximately 10 new cases per week, a dramatic decrease from the peak in mid-January when around 200 new cases were being reported weekly. According to data from the CDC, the South Carolina outbreak represents the largest measles outbreak in the US in more than 30 years. The total number of cases in the state is nearing 1,000, with the vast majority occurring in children under 18 years old.

Linda Bell, South Carolina's state epidemiologist, expressed cautious optimism during a March 4 press briefing. "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 stated. "We are very hopeful that the downward trend continues, but we have to be vigilant about the risk that we can see another surge." Bell noted that with schools going on spring break in March and April, there is potential for increased exposures as families travel and visit tourist attractions.

Threat to US Measles Elimination Status

The United States declared measles eliminated in 2000, a status achieved when there has been no ongoing transmission within the country for longer than a year. Even with cases in South Carolina abating, the nation now faces a serious risk of losing this hard-won public health achievement. The CDC has identified 12 measles outbreaks in the US this year, including significant clusters in Arizona, Texas, and Utah alongside the South Carolina situation.

More than 93 percent of the cases in South Carolina have occurred in people who were unvaccinated against measles. The outbreak has been fueled by low vaccination rates in schools, with social events around the winter holidays contributing to a surge of cases in January. Churches have also been identified as major sources of exposure, according to epidemiological investigations led by Bell and her team.

Public Health Response and Vaccination Uptick

The outbreak has prompted a significant increase in vaccination with the measles, mumps, and rubella (MMR) vaccine across South Carolina. According to the South Carolina Department of Public Health, Spartanburg County experienced a 133 percent increase in measles vaccination in February 2025 compared to the same period last year, representing approximately 900 additional doses administered. Statewide, an additional 7,000 doses of measles vaccinations were given in February, marking a 70 percent increase from the same time last year.

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, creating a diagnostic lag that contributes to the virus's spread. Measles can cause severe complications, including pneumonia and brain swelling, both of which have been documented in South Carolina cases.

Looking Forward: Cautious Optimism with Continued Vigilance

Early modeling of the outbreak suggested that South Carolina's measles situation could continue for six months or longer. However, the current downward trend indicates it may end sooner than initially predicted. Bell emphasized that while the decrease in new cases is encouraging, public health officials must remain prepared for potential resurgences, particularly with upcoming seasonal travel periods.

The national implications of this outbreak extend beyond South Carolina's borders. With measles cases appearing in multiple states and the total national count already surpassing half of last year's total in just over two months, the United States faces a critical juncture in maintaining its measles elimination status. Continued vaccination efforts, public awareness campaigns, and rapid response to new cases will be essential to preventing future outbreaks and protecting this important public health achievement.