Rapid Growth of Outbreak and Updated Case Numbers
A measles outbreak centered in Spartanburg County has continued to expand, with South Carolina health officials confirming 558 infections as of Friday, marking the largest active measles cluster in the United States. The outbreak has accelerated sharply in January, with 124 new infections reported in the three days preceding the latest update and 248 cases added in just the past week.
According to state data, 531 people are under quarantine orders and 85 are in isolation, with some restrictions extending through mid-February. Children and adolescents account for most infections: 134 cases involve children under age five, 372 involve individuals ages 5 to 17, and 39 cases are in adults. Thirteen cases have no recorded age data.
Vaccination information released by health officials shows that most confirmed cases occurred in unvaccinated individuals. Of the total, 483 patients had no measles vaccination, 6 had received only one of the recommended two MMR doses, 13 were vaccinated, and vaccination status was unknown for 56 individuals.
Public Exposure Sites and School Disruptions
Local officials have identified multiple public exposure locations across Spartanburg. Exposure windows were confirmed at a Walmart on Cedar Springs Road, the Wash Depot on South Pine Street, and Bintime Spartanburg on Blackstock Road. Officials emphasized that exposure risk was limited to the specified timeframes.
Schools across the county have also been heavily affected. As of January 16, quarantine orders had been issued for students at Holly Springs-Motlow Elementary, Campobello Graming School, Crestview Elementary, Libertas Academy, Fairforest Elementary, Berry Shoals Elementary, Oakland Elementary, Mabry Middle School, and Landrum High School. A combined total of more than 180 students remain at home under quarantine protocols following on-campus exposures.
Experts Cite Clusters of Low Vaccination Rates
Public health specialists involved in the response attribute the size and speed of the outbreak to declining vaccination coverage and an increase in nonmedical exemptions. Although countywide student vaccination coverage is estimated at around 90%, officials stress that this remains below the 95% threshold widely regarded as necessary to disrupt measles transmission.
New research published in JAMA highlights a sharp rise in vaccine exemption rates in the region, increasing from approximately 3% in 2020 to 8% during the 2024–2025 school year. State officials identified isolated schools with coverage far below county averages, including one reporting vaccination rates of just 20%.
National vaccination trends have shown similar patterns. Study co-author and physician-scientist Dr. Nathan Lo noted that even small clusters of under-vaccinated individuals are sufficient for measles to spread. “It doesn’t take much for a sustained outbreak once the virus enters a pocket of low immunity,” he said.
Cases Confirmed in North Carolina Following Cross-Border Spread
The outbreak has now expanded beyond South Carolina. Public health authorities in Buncombe County, North Carolina, announced two new cases involving unvaccinated siblings attending Asheville-Pisgah Christian School. North Carolina has now reported seven cases, six of which are linked to the South Carolina outbreak. Around 100 students and staff have been placed under quarantine due to the exposure.
County officials expressed concern about broader vaccination gaps, noting that Asheville-Pisgah Christian School has a measles immunization rate of only 41%. Across Buncombe County’s elementary schools, estimated coverage stands around 90%, with roughly 87% of students attending schools that fall short of the recommended 95% target.
National Attention and Ongoing Response Measures
Health experts assisting the outbreak response warn that containment remains challenging. Dr. Helmut Albrecht, an infectious disease physician working with Prisma Health and the University of South Carolina School of Medicine, said the outbreak is likely to grow further without improved population immunity. Measles is considered one of the most contagious viral diseases, with each case capable of causing widespread transmission in poorly immunized settings.
The outbreak has drawn national attention due to concerns that similar conditions exist in other regions with rising exemption rates. Experts caution that communities with weakening vaccination coverage may be vulnerable to comparable outbreaks in future seasons.
Public Information and Resources
Health officials remind residents that measles symptoms can take up to three weeks to develop following exposure. Individuals who suspect infection are encouraged to contact a healthcare provider before arriving for evaluation to prevent additional exposures in clinics and waiting rooms.
Prisma Health has launched a public hotline to answer questions regarding measles and the MMR vaccine, while the North Carolina Department of Health and Human Services has released a school-level vaccination lookup tool for residents seeking local immunization data.
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