At least 124 new measles cases have been reported in South Carolina since last Friday, health officials said.

This brings the total number of cases in the outbreak to 434. There are currently over 400 people in quarantine.

South Carolina has been facing a measles outbreak since early October, with the majority of cases in Spartanburg County, which borders North Carolina.

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Over the last few days, health departments in Georgia, Oregon and Virginia reported their states' first measles cases of 2026.

It comes as the United States recorded its highest number of measles cases since 1992. Last year, the U.S. saw 2,144 cases, with illnesses reported in 44 states.

Nearly 50 outbreaks occurred last year nationally, compared to 16 in 2024, and just four in 2023, CDC data shows. Almost 90% of cases were associated with outbreaks.

At least three deaths were recorded in 2025, including two among unvaccinated school-aged children in Texas and one among an unvaccinated adult in New Mexico, marking the first U.S. deaths from measles in a decade.

The CDC 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.

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In 2025, 93% of cases occurred among those who were unvaccinated or whose vaccination status was unknown. The remaining 3% were among people who received one dose and 4% among those who received the recommended two doses.

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 in the previous school year and the 95.2% seen in the 2019-2020 school year, before the COVID-19 pandemic.

ABC News' Youri Benadjaoud contributed to this report.