South Carolina health officials say measles is circulating undetected in the Upstate as Greenville reported an eighth case potentially tied to an outbreak in neighboring Spartanburg. Since September 25, seven cases there have been linked to transmission at Fairforest Elementary and Global Academy, exposing at least 153 unvaccinated children now under a 21-day quarantine. Authorities say it’s unclear how the Greenville patient was infected, underscoring active, unrecognized spread. County school immunization rates—90% in Spartanburg and 92.4% in Greenville—fall short of the 95% threshold, despite the MMR vaccine’s roughly 97% effectiveness.

Prepared by Olivia Bennett and reviewed by editorial team.