Trends in HIV testing and seroprevalence among key populations at public health centers in South Korea, 2011–2023: A nationwide analysis

Background Public health centers (PHCs) in South Korea provide free and anonymous HIV testing and serve as an essential component of the national testing infrastructure, particularly for populations underserved by conventional healthcare settings. Identifying temporal shifts in testing behavior and positivity is vital to inform targeted prevention and diagnostic strategies. Methods We analyzed HIV testing data from 260 PHCs nationwide between 2011 and 2023. Temporal trends in the number of tests, testing purposes, and HIV seroprevalence were assessed. Multivariable logistic regression was used to identify independent predictors of HIV positivity, and temporal changes were evaluated using the Mann–Kendall trend test. Results Over the 13-year study period, approximately 4.7 million HIV screening tests were completed at PHCs. Annual testing volume declined by nearly 75% during the COVID-19 pandemic but rebounded to 255,051 tests by 2023. Although fewer than 5% of national HIV tests were performed in PHCs, they identified 28.3% of newly diagnosed HIV infections in 2023. In that year, the overall HIV seroprevalence at PHCs was 0.165%, with elevated positivity among foreign nationals (0.677%), men (0.430%), individuals in their 20s (0.251%), and those undergoing anonymous (1.148%) or named (0.711%) client-initiated testing. Multivariable logistic regression revealed that male sex (adjusted odds ratio [aOR] = 9.48), foreign nationality (aOR = 6.22), voluntary testing (aOR = 7.67), and residence in metropolitan areas (aOR = 2.50) were significant independent predictors of HIV positivity ( p  < 0.001 for all). Trend analysis demonstrated significant increases in testing among individuals aged 30–39 years (Kendall’s tau = 0.821, p  < 0.001) and in antenatal care screening (Kendall’s tau = 0.897, p  < 0.001), reflecting expanded maternal health services and changing demographic patterns in test uptake. Conclusions Despite accounting for a small proportion of national HIV testing, PHCs consistently contributed a disproportionately large proportion of new diagnoses—especially among high-risk groups, such as men, foreign nationals, young adults, urban residents, and individuals, who actively seek confidential testing. Strengthening PHC-based services and expanding outreach tailored to these populations will be essential for enhancing early diagnosis and achieving national HIV prevention goals.