Outbreak Overview
The measles outbreak that began in South Carolina in October 2025 has surged to 876 confirmed cases as of February 3, 2026, with 700 reported since the start of the year. The spike reflects a national resurgence, as the United States recorded 2,267 cases in 2025—the highest in three decades.
Encephalitis: A Severe Complication
Encephalitis, or brain swelling, is a rare but life‑threatening complication of measles. It typically appears within 30 days of infection and can cause convulsions, deafness, or long‑term intellectual disability. Among children who develop measles‑related encephalitis, the mortality rate ranges from 10 % to 15 %.
- 19 measles‑related hospitalizations reported in South Carolina, including cases of pneumonia (the leading cause of measles death in children).
- Encephalitis occurs in a small fraction of measles cases but carries a high risk of severe outcomes.
Subacute Sclerosing Panencephalitis (SSPE)
SSPE is an even rarer, delayed form of brain inflammation that can emerge years after an initial measles infection. The disease remains dormant before triggering a progressive destruction of brain tissue, typically 7–10 years post‑infection. The estimated incidence is about 2 in 10,000 measles survivors.
In September 2025, Los Angeles County reported a child’s death from SSPE after the child had contracted measles as an infant, before the first MMR dose could be administered.
Vaccination Response
Public health officials have intensified vaccination efforts. In January 2026, South Carolina administered over 7,000 additional MMR doses compared with the same month in 2025—a 72 % increase statewide and a 162 % rise in Spartanburg County, the outbreak’s epicenter.
- MMR vaccine remains the most effective protection against measles and its complications.
- Pregnant women exposed to measles received immune globulin to reduce risks of preterm birth or miscarriage.
Public Health Measures
State law requires measles cases to be reported to the South Carolina Department of Public Health, though hospitalizations and complications are not mandated to be disclosed. Officials continue to monitor the situation, promote vaccination, and provide immune globulin to vulnerable populations.