A serological household survey on social determinants of the generalized HIV epidemic in southern Brazil.

This study explores HIV prevalence and its social determinants in the southernmost state in Brazil, where the HIV epidemic has historically been more severe. A population-based serological household survey was conducted in 56 sampled municipalities between 2020 and 2022. Adult residents completed electronic questionnaires and provided blood samples for HIV testing, following Brazilian guidelines. Statistical analysis employed survey-weighted methods and hierarchical robust Poisson regression models to investigate factors associated with HIV prevalence. Quality control measures and sensitivity analyses were included to ensure result robustness. Among 7978 analyzed participants, 81 HIV cases were serologically detected (51 also self-reported), resulting in an estimated overall HIV prevalence of 0.99% (95% CI 0.56-1.75). A generalized HIV epidemic was confirmed in the metropolitan health macro-region of Rio Grande do Sul, where HIV prevalence was 1.64% (95% CI 1.59-1.70). Socioeconomic position was the most important factor associated with HIV prevalence, even after adjustments. Disparities in HIV distribution across regions and subpopulations, combined with rising prevalence trends in other Brazilian states, support implementing a national serology household survey to create evidence-based policies addressing systemic social inequities. The high proportion of unknown HIV cases highlights the need for improved community-based testing strategies.