Still going

16 cases are linked to a church, which followed exposures at four schools last week.

A measles outbreak that began in South Carolina at the start of October is showing no signs of slowing as officials on Tuesday reported 27 new cases since Friday. Those cases bring the outbreak total to 111.

The southern state’s outbreak now rivals outbreaks ongoing in Utah and Arizona, which have tallied 115 and 176 cases, respectively. The outbreaks are threatening to cost the country its measles elimination status, which was earned in 2020 after vaccination efforts stopped the virus from spreading continuously. If the current transmission of the virus isn’t halted by January, the virus will have circulated for 12 consecutive months, marking it once again as an endemic disease in the US.

In an update on Tuesday, South Carolina’s health department suggested the spread is far from over. Of the state’s 27 new cases, 16 were linked to exposure at a church, the Way of Truth Church in Inman. And amid the new cases, new exposures were identified at Inman Intermediate School. That’s on top of exposures announced Friday at four other schools in the region, which led to well over 100 students being quarantined.

Currently, 254 unvaccinated and exposed people are in quarantine, including 43 students at Inman Intermediate School.

The quarantine period for measles is 21 days from the exposure, which is the maximum incubation period before the tell-tale rash appears. Measles is highly infectious, with up to 90 percent of unvaccinated or otherwise vulnerable people contracting the virus upon exposure. People infected with measles are infectious from four days before the rash appears to four days after its onset.

The outbreak is occurring in the northern region of South Carolina, with many cases identified in Spartanburg County, which contains Inman, as well as Greenville County. Both counties have low vaccination rates. For the 2024–2025 school year, only 90 percent of Spartanburg students were vaccinated, while Greenville’s vaccination rate was 92.4 percent. Those numbers are well below the 95 percent target needed to halt community transmission.

The two counties’ low vaccination rates are coupled with high rates of religious exemptions. Spartanburg has the state’s highest rate, with 8.2 percent of students exempt from the school vaccination requirement based on religious beliefs. Neighboring Greenville has a religious vaccination exemption rate of 5.3 percent.

Of the 111 outbreak cases, 105 were unvaccinated, three were partially vaccinated, two had an unknown status, and one case was fully vaccinated.

On a national scale, vaccination rates have declined overall amid misinformation spread by anti-vaccine activists, including current Health Secretary Robert F. Kennedy Jr. As such, measles cases are at a 33-year high, with nearly 2,000 cases this year and 46 outbreaks.

Beth is Ars Technica’s Senior Health Reporter. Beth has a Ph.D. in microbiology from the University of North Carolina at Chapel Hill and attended the Science Communication program at the University of California, Santa Cruz. She specializes in covering infectious diseases, public health, and microbes.