Background: Even though South Korea had eliminated measles in 2006, a localized cluster of measles occurred in a university dormitory in Gyeongsangbuk-do, South Korea, in 2024, involving 22 international students. This study aims to explore measles transmission and to inform future preventive measures. Methods: In a cross-sectional study, 299 international students from two local universities underwent a self-reported questionnaire survey and targeted serological testing by enzyme-linked immunosorbent assay two months after the cluster of measles cases. Statistical analysis used Pearson’s chi-square test, Fisher’s exact test, multivariate logistic regression, and Firth’s penalized logistic regression. Results: The overall seropositivity was 79.6%, and 78.0% among participants aged ≤ 30 years. Among multivariate analyses, nationality was independently associated with seropositivity (aOR up to 8.35 for Chinese students). Conclusions: These findings underscore the immunity gaps among international students, with seropositivity remaining below the 95% threshold required for herd immunity. Targeted serological screening and catch-up vaccination may help to improve immunity in mobile populations.
Qin et al. (Sat,) studied this question.