South Carolina Measles Outbreak Slows, But CDC Warns of Potential Underreporting

State health officials say no new cases reported in a week, but CDC modeling raises concerns about undetected infections.

Apr. 9, 2026 at 4:09am

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A ghostly, translucent X-ray image showing the intricate internal structure of a measles virus particle, conveying the clinical and scientific nature of the outbreak.As public health experts warn of potential underreporting, an X-ray view reveals the microscopic structure of the measles virus behind South Carolina's outbreak.Spartanburg Today

For the first time since South Carolina's record-breaking measles outbreak began last fall, the state has gone a full week without health officials learning of any new cases. However, a recent CDC report warns that there are likely some undocumented cases of measles in the affected region, raising the risk of continued spread.

Why it matters

The South Carolina measles outbreak has been the largest in the U.S. in decades, with nearly 1,000 documented cases. While the slowdown in new infections is encouraging, public health experts remain concerned about the potential for undetected transmission, especially as spring break travel approaches. Accurately tracking and containing measles outbreaks is crucial to protect vulnerable populations and prevent the disease from spreading more widely.

The details

The last day of the South Carolina measles outbreak would be April 26 if no more cases are reported, according to state epidemiologist Dr. Linda Bell. However, a recent CDC risk assessment warned that there are likely some undocumented measles cases in the affected region, raising concerns about ongoing transmission. The CDC's outbreak modeling has consistently indicated that a larger, prolonged outbreak lasting at least six months is the most likely scenario. While the rate of new cases has declined, the CDC cited 'inconsistent' or 'sub-optimal' compliance with isolation and quarantine, as well as low to moderate vaccination rates among unvaccinated residents in the outbreak area.

  • The South Carolina measles outbreak was first identified in early October 2025 with five known cases.
  • As of early March 2026, the state had 997 documented measles cases.
  • The last day of the outbreak would be April 26, 2026 if no more cases are reported.
  • South Carolina has gone a full week as of April 8, 2026 without any new measles cases reported.

The players

Dr. Linda Bell

South Carolina's state epidemiologist, who is leading the state's outbreak response.

Scott Thorpe

Executive director of the Southern Alliance for Public Health Leadership, who expressed concerns about potential underreporting of measles cases.

Dr. Robin LaCroix

A pediatric infectious disease specialist with Prisma Health, one of the major health systems treating measles cases in the outbreak area, who also raised concerns about underreporting.

Centers for Disease Control and Prevention (CDC)

The federal agency that has produced outbreak modeling assessments for the South Carolina measles outbreak, warning about the likelihood of some undetected cases.

Global Academy of South Carolina

A public charter school in Spartanburg where some of the earliest known outbreak cases and exposures occurred, with only 21% of students up-to-date on vaccinations.

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What they’re saying

“I think it's very unlikely we're at zero. One of the really challenging, frustrating things about measles is that there absolutely can be cases we don't catch, mild cases in particular.”

— Scott Thorpe, Executive director, Southern Alliance for Public Health Leadership

“I think that we have captured only a fraction of the people who have become infected with measles because if you were not ill enough to seek medical care, you are never captured in the numbers that are reported.”

— Dr. Robin LaCroix, Pediatric infectious disease specialist, Prisma Health

The takeaway

This outbreak highlights the ongoing challenges of accurately tracking and containing highly contagious diseases like measles, even as case numbers appear to decline. Public health experts warn that undetected transmission could fuel a resurgence, underscoring the importance of robust surveillance, high vaccination rates, and consistent compliance with isolation measures to protect vulnerable populations.