The disease usually develops seven to 14 days after exposure, but may take up to 21 days (which is the period of quarantine). Once it develops, it causes high fever and rashes that start on the head and spread downwards. People remain infectious for four days First The rash develops and four days after they appear. Complications can range from ear infections and diarrhea to encephalitis (inflammation of the brain), pneumonia, death in 3 out of 1,000 children, and, in very rare cases, a fatal neurological condition that can develop seven to 10 years after acute infection (subacute sclerosing panencephalitis).
Two doses of the measles, mumps and rubella (MMR) vaccine are considered 97 percent effective against the virus, and this protection is considered lifelong. Ninety-nine percent of the 310 cases in the outbreak in South Carolina are in people who are unvaccinated, partially vaccinated, or have unknown vaccination status (only 2 people were vaccinated).
The Centers for Disease Control and Prevention, which only has data through Jan. 6, has counted three confirmed cases for this year (two in South Carolina and one in North Carolina, linked to the South Carolina outbreak). Since then, South Carolina has reported 26 cases on Tuesday and 99 cases today, for a total of 125. North Carolina also reported three additional cases on Tuesday, again linked to the South Carolina outbreak. Overall, the US number drops to at least 131 on just nine days of the year.
In 2025, the country recorded 2,144 confirmed cases, the highest number of cases seen since 1991. Three people died, including two otherwise healthy children. In 2000, the United States declared measles eliminated, meaning it was no longer circulating consistently within the country. The country’s eradication status is at risk, including the ongoing outbreak in South Carolina.
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