The South Carolina measles outbreak that began in October 2025 has become the largest confirmed measles outbreak in the US since elimination was declared in 2000. Spreading across 32 schools over seven months, the outbreaks led the South Carolina Department of Public Health to institute widespread 21-day quarantines for exposed contacts lacking evidence of measles immunity, along with repeated school closures in some districts. Because chronic school absenteeism is known to depress academic performance and hinder students’ social development, understanding whether this approach actually curtails measles’ spread is critical for both public health and education policy.
In a commentary published in Vaccine, Dr. Nathaniel Hupert, associate professor of population health sciences and medicine, Dr. Ana Bento, assistant professor of infectious disease ecology, and her postdoctoral researcher, Dr. Siyu Chen, from the College of Veterinary Medicine at Cornell University, explained why quarantine alone cannot achieve containment in under-vaccinated communities. They found that the mean vaccination coverage at South Carolina schools with measles outbreaks was 82.5 percent, compared with 91 percent at schools with no outbreak. 41 percent of schools where students were exposed to measles underwent two, and in some cases, three rounds of quarantine. These repeatedly quarantined schools had significantly lower vaccination coverage and larger student populations than schools that were never exposed, or that required only a quarantine. In other words, these high-susceptibility, low vaccine coverage educational settings not only invite exposure but sustain recirculation.
The research team notes that while school-level vaccination coverage can prospectively flag sites at risk of both initial exposure and recurrence, further transmission often continues between households, places of worship, and other community settings in high-susceptibility locations. Maintaining high vaccination coverage across the broader population is therefore not just an infection-control measure in its own right, but a prerequisite for uninterrupted schooling wherever quarantine is used as a standalone response.
The authors argue that quarantine may be better employed as a means to buy time for expanded vaccination efforts, rather than as a containment strategy on its own. Framed this way, quarantine can make more efficient use of constrained public health capacity and may help prevent the rare but potentially devastating sequelae of measles infection, such as severe neurological complications.
Using publicly available data from the outbreak in South Carolina, the research team draws an important lesson for this current era of resurgent measles outbreaks: in communities where vaccination coverage falls below widely accepted herd immunity thresholds, quarantine only delays further transmission within and between schools. Using vaccination coverage data to identify the highest-risk schools before the next exposure event may allow public health officials to deploy existing vaccine resources more effectively to stop the spread of a once-vanquished disease, while protecting students’ critical educational experiences.
- Highlights