HIV molecular network in Mexico City (2021-2022): Understanding transmission dynamics through the role of newly diagnosed cases.

Objective: We aimed to infer and describe Mexico City's HIV genetic transmission network from 2021 through 2022 by characterizing its members based on time since HIV acquisition, as well as sociodemographic, clinical, and behavioural characteristics. Additionally, we assessed clustering potential according to time since HIV acquisition.

Methods: Individuals with a recent HIV diagnosis at the largest HIV clinic in Mexico City were invited to participate, completing self-administered questionnaires on sociodemographic, clinical, and behavioural characteristics. Blood samples were collected for analysis of the HIV pol gene using next-generation sequencing. The stage of infection at diagnosis was determined using an algorithm that includes antibody avidity tests. Genetic transmission network analysis used the Seguro HIV-TRACE tool.

Results: Of 6703 participants, 561 (8.4%) were identified as people newly living with HIV (PNLH). Transmission network analysis identified 896 clusters; 30.2% had at least one PNLH. Among all individuals, 43.5% formed clusters, with 11.8% being PNLH. PNLH added to a cluster showed higher odds for higher education, engaging in commercial sex, use of dating apps, annual HIV screening, and engaging in high-risk sexual practices (p < 0.05). Clusters with PNLH exhibited greater growth rates than those without PNLH (p < 0.05).

Conclusions: The presence of PNLH in clusters was associated with a higher growth rate. Tailored prevention strategies are crucial, including using dating apps for risk communication, promoting PrEP use, and safe sexual practices in sex venues, and enhancing harm reduction related to drug use. PNLH could be key candidates for interventions aimed at breaking transmission chains, including contact tracing.