Measles Cases Are Rising in South Carolina as U.S. Weathers Worst Outbreaks in Decades

There have been 1,912 cases of the measles in the U.S. this year, according to the Centers for Disease Control and Prevention. (Brandon Bell/Getty Images)

Key Points

• The U.S. has experienced 1,912 measles cases this year, marking the worst outbreak since 1992.
• Measles, mumps, and rubella vaccination rates have declined in 78% of surveyed U.S. counties since the COVID-19 pandemic.
• Only 10 states achieved the 95% MMR vaccination benchmark in the 2024-2025 school year, down from 20 states in 2019-2020.

For children in the U.S., this year has been the worst in decades for measles outbreaks. It isn’t over yet.

The potentially deadly virus, which a century ago killed a thousand people in the U.S. each year, was mostly eliminated in this country by 2000, thanks to near-universal adoption of the measles, mumps, and rubella vaccine.

Now, as vaccination rates fall, the virus is back. There have been 1,912 cases of the measles in the U.S. this year, according to the Centers for Disease Control and Prevention. That makes this year the worst for measles in the U.S. since 1992, by a long shot. Since 1997, there have only been two other years with more than 400 U.S. cases.

A series of measles outbreaks drew attention this spring, as the virus spread through Texas. While that surge has been extinguished, the nationwide case counts are now climbing again, as a new outbreak hits South Carolina.

There are currently 126 confirmed cases in South Carolina. The CDC says that most of the infections are in a single “under-vaccinated community” in Spartanburg.

In a Friday update, the South Carolina Department of Public Health reported 15 new cases of measles since Tuesday, 13 of which were from household exposures. Many of the cases reported over the past week come from a single church exposure, according to the CDC. There are now 267 people in quarantine and 13 in isolation in the state.

The CDC isn’t currently concerned that the Spartanburg-area’s cases will “develop into a large, long-running outbreak,” a U.S. Department of Health and Human Services spokesperson said Friday.

The CDC estimates that 91.2% of South Carolina kindergartners are vaccinated against measles, slightly below the nationwide average of 92.5%. The CDC has been in contact with state officials, and says that measles vaccine coverage in Spartanburg County is up 35%. Still, the agency says there has been “limited uptake” in the affected under-vaccinated community.

Though the largest outbreaks this year have been in Texas and South Carolina, there also have been more than a hundred cases each in Utah, Arizona, and New Mexico, and at least one case in most U.S. states.

The recommended two-dose series of MMR vaccines is 97% effective at preventing a measles infection, and a single dose is 93% effective. But MMR vaccination rates have been dropping since the Covid-19 pandemic. A June paper in the Journal of the American Medical Association found that MMR vaccination rates had fallen in 78% of surveyed U.S. counties since the pandemic.

Now, more states are falling below the 95% vaccination benchmark that is thought to prevent community transmission. Only 10 states had MMR vaccination rates of more than 95% in the 2024-2025 school year, down from 20 states in the 2019-2020 school year, according to an analysis of CDC data by the health policy group KFF.

The CDC recommends two MMR shots, one at age 12 to 15 months, and one at age 4 to six years. All states require children to have been vaccinated against measles to enter kindergarten, though exemptions are permitted, and some states allow exemptions based on religious or personal beliefs.

Measles vaccination rates have fallen in concert with growing vaccine skepticism, much of it rooted in a retracted and since discredited paper published in the Lancet in 1998, which alleged that the MMR vaccine had caused autism in some patients. Subsequent studies have found no link between the MMR vaccine and autism.

During Robert F. Kennedy Jr’s confirmation hearings following his nomination as HHS secretary in January, Sen. Bill Cassidy (R., La.), asked Kennedy if he would tell parents that the measles and hepatitis B vaccines don’t cause autism.

“That’s kind of a yes or no question,” Cassidy said.

“If the data is there, I will absolutely do that,” Kennedy said.

“The data has been there for a long time,” Cassidy said.

In a statement on Friday, HHS spokesman Andrew Nixon said Kennedy “has been clear that vaccination is the most effective way to prevent measles,” and that “individuals should consult with their healthcare provider on what is best for them.”

The CDC tweaked its guidelines for the shot earlier this year, following a vote of an influential outside advisory committee. The agency now says that young children should be given separate MMR and varicella shots, rather than a combined shot. The change was a minor one; only 15% of children under the age of four had received a combined MMRV shot before the new guidance, according to the CDC.

Corrections & Amplifications: A single dose of the measles, mumps, and rubella vaccine is 93% effective at preventing a measles infection. An earlier version of this article incorrectly said the single dose was 3% effective.

Write to Josh Nathan-Kazis at josh.nathan-kazis@barrons.com