South Carolina public health officials on Monday declared an end to the largest measles outbreak in the U.S. since 1991.
On Sunday, the state marked 42 days with no new cases reported related to the outbreak. Over a six-month period starting last October, 997 people were infected with measles in South Carolina. Most of them were unvaccinated children. At least 21 people were hospitalized with measles complications.
The outbreak was largely contained to the northwest region of the state. It never went statewide, "thanks to timely investigations, identification of those exposed, and people's willingness to stay home," said Dr. Edward Simmer, interim director of the South Carolina Department of Public Health. "In many ways, this was a textbook response to dealing with an outbreak."
The measles virus can lead to serious complications, including pneumonia and brain swelling. At a briefing Monday, Dr. Brannon Traxler of the South Carolina Department of Public Health said while many measles cases were mild, "it was, at times, life- threatening or potentially long lasting for others."
Measles can be fatal. Last year three people — including two school-age children in Texas — died from the disease. While most people recover from measles, it can cause long-lasting complications, including immune amnesia, a phenomenon where the virus wipes out parts of the immune system, leaving kids vulnerable to new infections for several years.
And children infected before the age of 2 are at higher risk of developing a fatal, degenerative neurological condition that typically develops seven to 10 years after a measles infection.
The South Carolina outbreak was centered in Spartanburg County, where the majority of schools had measles vaccination rates below the 95% threshold required to prevent outbreaks. Traxler says the state succeeded in stopping the outbreak, in part, because of an uptick in people getting the vaccine. Measles is one of the most contagious diseases known.
But Traxler says pockets of people who lack immunity — gained either through infection with measles or vaccination — remain in Spartanburg County and throughout the state, "so there is an ongoing risk there."
Dr. Martha Edwards, president of the South Carolina chapter of the American Academy of Pediatrics, says she's heard from pediatricians who have had previously hesitant families come back to request the measles vaccine after seeing the impact of the disease on their community.
"I think that families that experienced measles kind of passed the word around that this was not such an easy illness," she says. "It was really rough, that they were really worried."
While South Carolina's outbreak is over for now, more than 20 other new outbreaks have been reported this year across the U.S., according to the Centers for Disease Control and Prevention. That includes large outbreaks in Texas, Florida and Utah — each with more than 100 confirmed cases of measles.
The resurgence of measles in the U.S. comes as vaccination rates have been falling across the country. Nationwide, 92.5% of kindergartners had received the measles vaccine in the 2024-2025 school year, according to the CDC. In many communities across the country, those figures are much lower, creating the conditions needed for measles outbreaks to spread. Experts say all that's needed is one spark to ignite it.
Last year, the U.S. reported 2,288 cases of measles — the most since the year 2000, when the disease was declared eliminated in the country. That's a technical designation given to countries that have gone a year without a continuous chain of transmission.
That status is now under threat. With 1,792 measles cases confirmed so far this year, according to the CDC, the U.S. is on track to surpass last year's record case count.
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