Special Issue: New Horizons in HIV and Reproductive Health Research: HIV Acquisition and Reproductive Health in Key Populations.

Despite tremendous scientific breakthroughs in the prevention of HIV in the past decade, considerable gaps in knowledge persist regarding biologic vulnerabilities among the key populations who bear the greatest burden of the global HIV pandemic. Key conditions and subgroups with increased susceptibility to HIV include transgender and gender diverse persons and cisgender women-specifically during pregnancy, those who are survivors of sexual violence and female sex workers. Across groups, increased vulnerability to HIV is related to both increased physiologic susceptibility as well as synergistic social vulnerabilities, such as social marginalization and shifts or discordance in power dynamics in sexual and interpersonal relationships-which can both increase exposure to HIV and decrease access to and utilization of HIV prevention modalities (e.g., HIV pre-exposure prophylaxis, post-exposure prophylaxis, and barrier protection). In this review we examine epidemiology, immune system and hormonal regulation, microbiome, and known gaps in science associated with HIV acquisition among these key populations/conditions.