Epidemiological Trends, Transmission Dynamics, and Mortality Patterns of HIV/AIDS in South Korea, 1985-2024: A...

Background: South Korea has documented HIV cases since 1985; however, comprehensive longitudinal analyses integrating incidence, mortality, transmission dynamics, and immunological staging across the full surveillance period remain limited. This study aimed to characterize epidemiological trends from 1985 to 2024 and project future trajectories through 2028. Methods: We analyzed nationally reported aggregate HIV/AIDS surveillance data from the Korea Disease Control and Prevention Agency (KDCA) via KOSIS (1985-2024). Annual HIV incidence, AIDS case notifications, HIV-related mortality, transmission route distributions, CD4+ T-cell counts at diagnosis, and cumulative prevalent cases stratified by sex were examined. Statistical methods included simple and multiple linear regression, Pearson and Spearman correlation, hierarchical regression analysis, and time series forecasting using Holt-Winters exponential smoothing and ARIMA (AutoRegressive Integrated Moving Average) modeling. Missing data in transmission route classification (29.6% non-response in 2024) were addressed through sensitivity analysis and explicit discussion of potential misclassification bias. Results: HIV annual incidence increased significantly from one case in 1985 to a peak of 1081 in 2014 (slope = +39.25 cases/year, R² = 0.912, p < 0.001), followed by a significant decline to 714 cases in 2024 (slope = -38.76 cases/year, R² = 0.879, p < 0.001). A strong positive correlation was observed between HIV and AIDS incidence (Pearson r = 0.627, p = 0.017; Spearman ρ = 0.785, p < 0.001). The AIDS/HIV notification ratio declined significantly from 0.307 in 2011 to 0.196 in 2024 (slope = -0.006/year, R² = 0.421, p = 0.012). The male-to-female notification ratio increased from 0.8:1 in 1987 to 22.0:1 in 2024 (R² = 0.600, p < 0.001). Among reported sexual transmissions, the proportion attributable to MSM increased from 0% in 1985 to 63.7% in 2024 (slope = +1.30%/year, R² = 0.804, p < 0.001). The proportional mortality rate declined significantly from 2.31% in 2011 to 0.93% in 2024 (slope = -0.105%/year, R² = 0.821, p < 0.001). Time series forecasting projected continued decline to approximately 666 new HIV cases and 105 AIDS notifications annually by 2028. Conclusions: The South Korean HIV epidemic has undergone a profound epidemiological transition-from heterosexual-predominant early growth through a 2014 peak toward a declining, MSM-concentrated trajectory-with mortality progressively decoupled from incidence through expanded antiretroviral therapy coverage. Targeted MSM-focused prevention, expansion of PrEP access, and sustained ART scale-up are essential to achieving national HIV elimination targets.