The record-breaking measles outbreak in South Carolina continues to grow with 89 new cases reported since the last update on Friday.
This brings the total number of cases in the outbreak to 789.
At least 557 people are currently in quarantine across the state, including students from various schools.
This is South Carolina’s largest measles outbreak in over 30 years, a spokesperson for the state’s health department told ABC News.
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There have been at least 416 confirmed measles cases across the United States so far this year, the latest CDC data shows.
CDC data shows that the majority of cases occur among people under 19. About 2% of all measles cases in the U.S. have been hospitalized.
Dr. Kristin Moffitt, an infectious diseases physician at Boston Children’s Hospital, previously told ABC News she is “very alarmed” by the increase in measles cases in the U.S. over the last year or two.
BSIP/Universal Images Group via Getty Images – PHOTO: The measles virus.
“I’m very worried about our current year already,” she told ABC News. “Exceeding 2,000 cases in the last year is indeed alarming [and] … I am worried that even our current year is off to a very concerning start.”
Moffitt said that declining vaccination rates across the U.S. are behind the recent increase in measles cases.
“This is entirely due to declining vaccination rates,” she said. “It’s very clear based on where these outbreaks are occurring.”
The CDC currently recommends that people receive two doses of the MMR vaccine, the first at ages 12 to 15 months and the second between 4 and 6 years old. One dose is 93% effective, and two doses are 97% effective against measles, the CDC says.
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However, federal data shows vaccination rates have been lagging in recent years. During the 2024-2025 school year, 92.5% of kindergartners received the MMR vaccine, according to data. This is lower than the 92.7% seen in the previous school year and the 95.2% seen in the 2019-2020 school year, before the COVID-19 pandemic.
The national trends mirror those see in counties across the U.S. A recent map from ABC News — a collaboration with researchers from Boston Children’s Hospital, Harvard School of Medicine and Icahn School of Medicine at Mt. Sinai that allows people to type in their ZIP code and see the measles risk in their area — found a wide range of risks in areas across the U.S.
Some counties and ZIP codes fell into the “lowest risk,” with 85% or more of children under 5 years old receiving one or more measles vaccine dose to “very high risk,” with fewer than 60% of children under age 5 receiving one or more measles vaccine doses.
ABC News’ Mary Kekatos and Dr. Richard Zhang contributed to this report.
