Nationwide seroprevalence of severe fever with thrombocytopenia syndrome virus in South Korea: Regional patterns and public health implications

OBJECTIVES: Severe fever with thrombocytopenia syndrome (SFTS) is a tick-borne viral disease with a high fatality rate and is endemic to East Asia. This study aimed to estimate the seroprevalence of SFTS virus (SFTSV) antibodies in South Korea and analyze regional and demographic variations to guide public health strategies. METHODS: We conducted a cross-sectional study using 12,684 residual serum samples from clinics in 17 administrative regions (July 2019-June 2020) using a double-antigen sandwich enzyme-linked immunosorbent assay. Crude and standardized seroprevalence was calculated, and trends were assessed using generalized additive mixed models. RESULTS: The overall crude seroprevalence was 1.63 % and was higher among older adults, particularly those aged 80-99 years (3.03 %). Jeju (2.99 %) and Gangwon (2.28 %) Provinces had the highest standardized seroprevalence. SFTSV seroprevalence did not differ significantly by sex or urban-rural status but was higher in agricultural regions, suggesting occupational exposure as a risk factor. CONCLUSIONS: This nationwide estimate of SFTSV seroprevalence highlights high-risk groups, particularly older adults. These findings provide a baseline for surveillance and targeted interventions to mitigate SFTS risk and inform public health strategies in East Asia.