Measles Outbreak in South Carolina: Update on Complications

Children affected by measles during the ongoing outbreak in South Carolina have unfortunately developed a serious complication known as encephalitis, which is the swelling of the brain. This update was shared by state epidemiologist Linda Bell on Wednesday.

The outbreak began back in October with just a few cases. However, as of February 3, the number of infections has surged to 876, with around 700 of those reported since the start of the year. This sudden increase signals that the United States might face another challenging year regarding measles, especially after reaching over 2,267 cases—the highest in three decades—in 2025. This rise is largely attributed to falling vaccination rates nationwide.

Encephalitis is a rare yet severe complication of measles, which can result in convulsions and may lead to hearing loss or cognitive disabilities in affected children. Typically, this complication manifests within 30 days following an initial measles infection, either through direct viral infection in the brain or due to an immune response causing inflammation. Alarmingly, among children who develop measles encephalitis, between 10 to 15 percent may not survive.

Currently, it’s uncertain how many children in South Carolina have experienced this severe complication. State law mandates reporting measles cases to the South Carolina Department of Public Health; however, details regarding hospitalizations and complications aren’t required to be disclosed.

“We don’t provide details on individual outcomes, but encephalitis is certainly a recognized complication of measles,” Bell mentioned during a media briefing. “Whenever there’s brain inflammation, it can lead to long-term issues such as developmental delays, which can have irreversible effects.”

As of now, the department is tracking 19 hospitalizations related to measles in the state, which includes some cases of pneumonia—this condition affects about one in 20 children with measles and is a significant cause of mortality in these cases.

Additionally, Bell noted that some pregnant women who were exposed to the virus have required immune globulin, a solution that offers temporary protection against measles to those not vaccinated. Exposure to measles during pregnancy can lead to preterm birth or even miscarriage.

A rare condition known as subacute sclerosing panencephalitis (SSPE) can emerge years after a measles infection. In September, the death of a school-aged child due to SSPE was reported by the Los Angeles County Department of Public Health. This child had been infected with measles as an infant before being eligible for the vaccine, which is typically recommended between 12 and 15 months of age.

SSPE occurs after the initial measles infection, where the virus remains silent in the brain and ultimately triggers a damaging inflammatory response that destroys brain tissue over time. This condition often surfaces seven to ten years after the person seems to have recovered from measles. Estimates suggest that about two out of every 10,000 people who contract measles eventually develop SSPE.

The measles, mumps, and rubella (MMR) vaccine is the most effective method to prevent measles and its serious complications.

This January, over 7,000 additional doses of the MMR vaccine were administered across South Carolina compared to January 2025, marking a 72 percent increase. Specifically, in Spartanburg County—where the outbreak is concentrated—there was a remarkable 162 percent rise, with more than 1,000 additional doses given. January has been noted as the most successful month for measles vaccinations during this outbreak, according to Bell.