Grant: Pr.Gr.- PA: Sex/Gend. in Health Res.- Sex/gender sci. health equity pri. Comm.

While biological sex is often assigned at birth on the basis of reproductive functions, gender is often more complex, developing over time and includes on social and cultural variables. While sex and gender often correlate (male/men, female/women) in "cis" individuals, "trans" individuals have a gender that is discordant with their biological sex. Transgender (TG) people in Africa have not been widely incorporated into public health responses to control sexually and blood borne transmitted infections (STBBI), despite evidence of their increased marginalization and increased STBBI risk in many African contexts. HIV prevalence is consistently higher in transgender women (TGW) compared to cisgender men who have sex with men (cis-MSM), despite shared risk pathways. We have worked in Nairobi, Kenya for the past several decades, including on multidisciplinary studies of STBBI risk in sexual and gender minorities who sell sex. On the basis of our STBBI prevention and treatment program catering to >1,500 TG people, and in collaboration with the TG community, we propose to unravel factors that increase STBBI risk in TG people. These range from high level (or "structural") factors such as stigma, socioeconomic, and legal factors, exposure to violence, substance use and mental health challenges, "individual" exposures such as condomless sex and engagement in sex work, and access to STBBI prevention and treatment programs, and "biological" factors such the microbiota and immune responses. Understanding each of these layers of STBBI risk in TG people in Nairobi is an important step toward improving the health of an underserved population through tailored, community-centred interventions.