At least 99 new measles cases are being reported in South Carolina amid the state’s outbreak.
This brings the total number of cases in the state to 310. There are currently 200 people in quarantine, according to health officials.
The outbreak has been ongoing as state health officials continue to push for vaccinations. The majority of cases are located around Spartanburg County.
“The number of those in quarantine does not reflect the number actually exposed,” Dr. Linda Bell, the state epidemiologist, said in a press releases. “An increasing number of public exposure sites are being identified with likely hundreds more people exposed who are not aware they should be in quarantine if they are not immune to measles. Previous measles transmission studies have shown that one measles case can result in up to 20 new infections among unvaccinated contacts.”
South Carolina’s department of public health said it sent a statewide health alert on Jan. 7, “advising health care providers and facilities of the importance of heightened awareness for measles and recommended measures for the use of masks and rapid isolation of suspect measles cases to protect people in health care settings from exposures.”
MORE: US measles cases surpass 2,000, highest in 30 years: CDC
The growing outbreak in South Carolina comes as the United States recorded its highest number of measles cases since 1992. Last year saw 2,144 cases, with illnesses reported across almost every single state. Nearly 50 outbreaks occurred last year nationally, compared to 16 in 2024, and just 4 in 2023.
An estimated 93% of the cases last year were in those who were unvaccinated or had unknown status, CDC data shows.
The Centers for Disease Control and Prevention currently recommends that people receive two doses of the MMR vaccine, the first at ages 12 to 15 months and the second between 4 and 6 years old. One dose is 93% effective, and two doses are 97% effective against measles, the CDC says.
However, CDC data shows vaccination rates have been lagging in recent years. During the 2024-2025 school year, 92.5% of kindergartners received the MMR vaccine, according to data. This is lower than the 92.7% seen the previous school year and the 95.2% seen in the 2019-2020 school year, prior to the COVID-19 pandemic.
ABC News’ Mary Kekatos contributed reporting.
