Seroincidence Study Among Men Who Have Sex With Men and Transgender Women - The ImPrEP Seroincidence Study. A Sub-study of Implementation of HIV Pre-exposure Prophylaxis (PrEP) for Men Who Have Sex With Men and Transgender People: A Demonstration Project in the Context of Combined Prevention in Brazil, Mexico and Peru - the ImPrEP Study

PrEP (pre-exposure prophylaxis) is an effective prevention strategy in which HIV-negative individuals take antiretroviral drugs (tenofovir disoproxil fumarate and emtricitabine - TDF/FTC) to reduce HIV acquisition. Clinical studies have shown that the TDF/FTC combination protects MSM and transgender women against HIV infection. According to the PROUD study, PrEP can decrease the risk of HIV infection among MSM by 86% (90% CI 64-96). The international community recognizes that PrEP can be an additional tool in the framework of a combination prevention package for those most at risk of contracting HIV. Data on HIV incidence among MSM and trans women are largely unknown. In Brazil, Mexico and Peru, data on the incidence of HIV among MSM and trans women are very scarce, limited to small cross-sectional studies.Current methods used to determine HIV-1 incidence have many limitations. These methods include mathematical modeling, retrospective calculations of AIDS case reports, age-based prevalence determinations, and prevalence determinations with multiple rounds of longitudinal surveys to estimate HIV incidence, which require numerous assumptions and inputs and can pose additional challenges in the era of expansion of antiretroviral therapy (ART) and increased survival of HIV-1 infected individuals. On the other hand, prospective longitudinal cohort studies of high-risk individuals can be used to estimate incidence; however, they are often labor-intensive, complex, very expensive, difficult to implement in most countries, and have recruitment biases. Laboratory methods can be unbiased and do not require complicated assumptions and case-by-case weighting. The cross-sectional use of Recent HIV Infection Tests (TRIs) based on biomarkers offers, in principle, accessible, reliable and low risk of bias options for estimating incidence.