Growing U.S. measles outbreaks trigger school quarantines
A surge of measles in the United States is forcing hundreds of unvaccinated children to stay home from school for at least three weeks. In South Carolina’s upstate, 153 students have been quarantined after exposure to the virus, with authorities reporting active transmission. In Minnesota, 118 students in the Minneapolis–St. Paul area are under quarantine as exposure to measles has led health officials to take precautionary measures while cases rise.
The quarantines mean a disruption in learning that could stretch into early February, as parents monitor fever, rash and other symptoms that can indicate active infection. Health officials say the goal is to interrupt transmission chains and protect vulnerable populations, including those who cannot be vaccinated for medical reasons.
What’s driving the current outbreaks
Public health officials describe the situation as ongoing and unrecognized in parts of the community. In Greenville County, South Carolina, a new measles case was diagnosed with no known link to earlier cases, illustrating how the virus can circulate quietly before being detected. Dr. Linda Bell, the state epidemiologist, noted that the case underscores active community transmission and the need for rapid containment measures.
The outbreaks in South Carolina involve two schools: an elementary school and a charter school that serves students from kindergarten through 12th grade. Unvaccinated children exposed to the virus are excluded from school for three weeks—the maximum window in which measles exposure can lead to symptoms.
Vaccination gaps and herd immunity concerns
Vaccination rates help determine how quickly measles can spread. NBC News data show Spartanburg County’s MMR vaccination rate at about 90% for the 2024–25 school year, while Greenville County’s rate is just over 90%. Health experts say the 95% threshold is typically needed to achieve herd immunity and prevent outbreaks, meaning even small gaps can spark localized transmission.
Across the country, officials are watching a broader trend: childhood vaccination rates have fallen in many counties since 2019. An NBC News investigation documented notable declines in vaccination coverage, raising concerns that measles, once declared eliminated in the U.S., could rebound in pockets of the population.
Quarantine as a tool amid rising cases
In Minnesota, the 118 quarantined students form part of a developing cluster that health authorities continue to monitor closely. Michael Osterholm, a respected infectious disease expert, warned that such quarantines may become more common as measles transmission persists in some communities. He emphasized the need for vigilance and consistent public health messaging.
Officials remind families that handwashing, vaccination, and staying home when sick are essential practices to reduce transmission. The current outbreaks in the western U.S. and the Midwest highlight how quickly a disease with a long history of elimination can re-emerge when vaccination coverage dips.
What families should watch for
Measles symptoms can start with fever, cough and runny nose, followed by red eyes and a distinctive rash. White spots inside the mouth can also appear. If symptoms arise, families should contact healthcare providers promptly and limit contact with others to prevent further spread.
Looking ahead
As the U.S. faces multiple measles exposures across states, public health officials stress the importance of vaccination as the most effective defense. The pace and scope of outbreaks will depend on vaccination uptake, timely detection, and community adherence to quarantine guidance when cases are identified. If the current trend continues into January, there could be renewed scrutiny of measles elimination status in the United States.
Public health departments continue to investigate exposures, provide guidance to schools and communities, and encourage parents to ensure their children are up to date with MMR vaccination. The goal remains clear: protect children and communities while preventing further spread of this highly contagious disease.
