Abstract
BACKGROUND: Sustaining measles elimination in the post-elimination era presents increasing challenges due to global resurgence and waning vaccine-induced immunity. We aimed to evaluate epidemiological trends, vaccination strategies, and population immunity associated with achieving and maintaining measles elimination in Taiwan. METHODS: We conducted a comprehensive analysis of national surveillance data from 1991 to 2024, including case notifications, viral genotypes, vaccination coverage rates, and surveillance performance indicators. Three population-based seroprevalence surveys conducted between 2002 and 2020 were reviewed to assess age-specific immunity. Descriptive analyses were performed to characterize long-term epidemiological and immunological trends. RESULTS: From 1993 to 2024, the annual number of measles cases remained consistently below 50, except in 2019. Vaccination coverage for both MMR1 and MMR2 has exceeded 95% since 1998, with MMR1 coverage remaining above 97% between 2009 and 2024. Genotyping evidence confirms the interruption of endemic transmission since 2006; furthermore, as of 2024, no continuous chains of transmission lasting longer than 12 months have been recorded. National seroprevalence surveys monitoring measles-specific IgG antibodies revealed declining antibody levels among adolescents and young adults, with seropositivity as low as 36.7% in specific cohorts. Despite this, transmission following importations has remained limited, with minimal secondary spread. CONCLUSIONS: Taiwan has successfully sustained measles elimination through high vaccination coverage, robust surveillance, and targeted interventions. Although serological evidence indicates waning immunity, epidemiological data suggest preserved population-level protection, likely mediated by immunological memory. Targeted booster strategies for high-risk groups may be more appropriate than universal additional dosing in post-elimination settings.