The United States is experiencing another sharp rise in measles infections, with new clusters developing almost as rapidly as the surge seen earlier this year in West Texas. Fresh figures released this week by the US Centers for Disease Control and Prevention show an increase of 84 new infections nationwide, the highest weekly total since April, when cases jumped by roughly 100 per week.
While Texas has not reported additional cases since state leaders announced the end of its large outbreak in mid-August, attention has now shifted to South Carolina, where infections are spreading at an alarming rate. Health officials say over 250 individuals have been placed in quarantine after possible exposure, while 16 infected people remain in isolation. According to state epidemiologist Dr. Linda Bell, several residents have been quarantined twice because they did not gain immunity through vaccination or previous infection following their first exposure.
Quarantines Rise As Cases Accelerate
“This outbreak is a clear reminder that measles has a maximum incubation period of 21 days,” Dr. Bell said during a Wednesday briefing. “Having to repeat the quarantine period is a significant disruption for students, workers, and families. Vaccination remains the strongest tool we have to prevent the level of interruption this disease is causing in our communities.”
Dr. Bell added that cases are now increasing more quickly than before. While most residents have complied with public health guidance, she warned that holiday gatherings, increased travel, and lower-than-needed vaccination rates have fueled the uptick. Measles spreads with extreme ease, and even a small number of unvaccinated people can sustain large outbreaks.
State health data show 111 confirmed cases in South Carolina since the outbreak began in October. Of those, at least 105 individuals had never received even one dose of the measles-mumps-rubella (MMR) vaccine. The recommended two-dose MMR series offers approximately 97% protection against infection.
Most cases have been identified in the state’s Upstate region near Greenville. Dozens of new infections have been traced to exposure at a local church, though schools and health care facilities have also been involved in transmission.
“The majority of cases can be linked to specific exposure events,” Bell noted. “However, in areas with low vaccination coverage, every new case creates a ripple effect. The number of potential contacts expands rapidly, which is exactly how this virus spreads so efficiently.” She emphasized that increasing vaccination rates at the same speed as the outbreak grows is the only way to slow transmission.
National Outlook: A Record Year for Measles
South Carolina is not alone. Utah and Arizona continue to battle a long-running outbreak along their shared border. Arizona has reported 176 cases, the second-highest total in the country this year, while Utah has confirmed 115 cases.
The United States has now recorded more than 1,900 measles cases in 2025, making it the worst year since the disease was declared eliminated domestically 25 years ago. Nearly all infections have occurred in people who were not vaccinated.
If the current pace continues into the new year, the U.S. could risk losing its measles elimination status — a milestone Canada already lost last month after sustained outbreaks.
According to the CDC, 47 outbreaks have been documented across the nation in 2025, nearly triple the number seen the previous year. More than 200 individuals have been hospitalized, and tragically, three people — including two young children — have died as a result of the disease.
