The holiday-period surge pushes South Carolina toward one of the worst state-level measles outbreaks in recent memory, as federal data show 2025 was the nation’s worst year for measles since 1991 and health experts warn the U.S. is on the verge of losing its decades-long status of having eliminated local measles transmission.
South Carolina’s measles outbreak grew to 310 confirmed cases on Friday after state health officials reported 99 new cases over three days, with the virus spreading beyond Spartanburg County to families in North Carolina and Ohio who traveled to the outbreak area during the holidays.
As of Friday, 200 people were in quarantine and nine in isolation, according to state health department data. The surge pushes South Carolina toward one of the worst state-level measles outbreaks in recent memory, as federal data show 2025 was the nation’s worst year for measles since 1991 and health experts warn the U.S. is on the verge of losing its status of having eliminated local measles transmission.
Quarantine Understates True Exposure, Health Official Says
Dr. Linda Bell, who leads the South Carolina health department’s outbreak response, said the quarantine figures do not capture the full scale of exposure.
“The number of those in quarantine does not reflect the number actually exposed,” Bell said. “An increasing number of public exposure sites are being identified with likely hundreds more people exposed who are not aware they should be in quarantine if they are not immune to measles.”
State health officials said the holiday-period spike had been expected, driven by travel, family gatherings and low vaccination rates in the northwestern part of the state. Since the outbreak began in October, Bell has warned that the virus was spreading undetected in the area. Hundreds of school children have been quarantined from school, some more than once.
Two Active Hot Spots, a Worsening National Picture
South Carolina is one of two active measles hot spots in the United States. A separate outbreak on the Arizona-Utah border has resulted in 337 cases since August.
The Centers for Disease Control and Prevention confirmed 2,144 measles cases across 44 states in 2025, the nation’s worst year for measles spread since 1991.
As the one-year anniversary of a Texas-New Mexico-Oklahoma outbreak approaches — which sickened at least 900 people and killed three — health experts say the vaccine-preventable virus is on the verge of making a lasting comeback in the country. At that point, the U.S. would lose its status of having eliminated local measles transmission, as Canada did in November. International health experts say the same strain is spreading across the Americas.