South Carolina measles outbreak is largest in U.S. since measles was declared eliminated

South Carolina has reported 789 measles cases since the start of an outbreak in October 2025. Image taken in South Carolina on October 20, 2025. Ken Ruinard/USA Today Network/Imagn Images via CNN Newsource

(CNN) — The fast-growing measles outbreak in South Carolina is now the largest in the United States since the disease was declared eliminated more than two decades ago.

With 789 cases reported as of Tuesday, the South Carolina outbreak surpassed a massive outbreak in Texas, which reached 762 cases before it ended in August last year. Two children died during the outbreak in Texas.

South Carolina, which first reported cases in October, has added more than 600 cases in 2026 alone. At least 18 people – adults and children – have been hospitalized for complications of measles, the state health department said Tuesday, and no deaths have been reported.

There are an additional 557 people in quarantine in South Carolina, meaning they may have been exposed to measles and don’t have immunity to it through vaccination or prior infection. The health department reported exposures at three additional schools Tuesday, on top of existing quarantines among students at 20 others.

Cases in North Carolina and Washington have also been linked to the South Carolina outbreak.

Measles was declared eliminated in the US in 2000, meaning there has not been continuous transmission for more than a year at a time.

Before 2025, there were an average of about 180 measles cases reported each year since elimination, according to U.S. Centers for Disease Control and Prevention data. The U.S. reported more than 2,200 confirmed measles cases in 2025 — significantly more than there have been in any year since 2000.

The CDC said on Friday that there have been 416 confirmed measles cases reported in the U.S. so far in 2026, but its update included data up until Thursday, before South Carolina’s latest numbers came in. At least 14 states have reported a confirmed measles case so far this year, and another large outbreak continues to grow along the Arizona-Utah border.

The spread of measles over the past year has left the U.S. at risk of losing elimination status, which the Pan American Health Organization could decide to revoke when it meets in April.

The CDC previously called measles elimination “a historic public health achievement,” possible in large part because of vaccination. The measles vaccine was licensed in 1963 and the combination measles-mumps-rubella (MMR) vaccine that is most commonly used first became widely available in the US in the 1970s.

Previously, the country’s elimination status was threatened in 2019, amid large outbreaks in New York concentrated in Orthodox Jewish communities in Brooklyn and Rockland County.

Under U.S. Department of Health and Human Services Secretary Robert F. Kennedy Jr., a longtime vaccine skeptic, the federal government’s posture toward measles has changed.

CDC Principal Deputy Director Dr. Ralph Abraham, a former Louisiana surgeon general who ended some vaccine promotion in his state before taking his new post late last year, argued last week that ongoing measles transmission from the Texas outbreak, which started in January 2025, has not been proved.

Nonetheless, Abraham said the loss of measles elimination status would “not really” be significant.

“It’s just the cost of doing business with our borders,” Abraham told reporters in a briefing. “We have these communities that choose to be unvaccinated. That’s their personal freedom.”

Abraham added that “vaccination remains the most effective way to prevent measles” and said the CDC is “here to help,” but they’re willing to listen to alternatives “for treatment and prevention.”

The vast majority of cases in the South Carolina outbreak are among children, nearly all of whom were not fully vaccinated with the recommended two doses of MMR vaccine. Of the 789 cases reported as of Tuesday, more than 700 were not vaccinated or had not received the two recommended MMR doses, the health department said.

State health officials have been encouraging vaccination, including through facilitating mobile health unit vaccination events, to try to contain the outbreak.

In Spartanburg County, the epicenter of the outbreak, 90% of students had required immunizations in the 2024-25 school year, among the lowest vaccination rates in the state, according to state data – with some schools there reporting much lower rates. Public health experts say a 95% vaccination rate is typically needed to keep measles from spreading in a community because the virus is so contagious.

The MMR vaccine is widely available at doctors’ offices, pharmacies and health departments, and is free for many families through the Vaccines for Children program or health insurance, State Epidemiologist Dr. Linda Bell said last week.

“As we continue to watch this daily surge in cases, [the Department of Public Health] strongly encourages those who are not protected to take advantage of the opportunity to get protected against unexpected exposures and illnesses now to help us stop this outbreak and to help us protect our communities,” Bell said.

Meg Tirrell, Deidre McPhillips, Jamie Gumbrecht, CNN