ABSTRACT In the United States (US), HIV prevalence among transgender women (TW) is high (~14%). Yet, uptake of HIV pre-exposure prophylaxis (PrEP) among TW is low (5-20% of US TW report ever using PrEP) and adherence is often poor. This is in large part because TW were poorly represented in PrEP trials, leading to data quality issues, and gaps in knowledge about TW's experiences with PrEP. Our previous studies and other literature found that TW are unwilling to use biomedical HIV prevention strategies unless they have been tested for safety, tolerability, and efficacy with TW. HIV vaccines are a promising alternative or companion to PrEP, since vaccines would not require long-term, near-perfect adherence to a daily or bi-monthly product. However, it is currently impossible to evaluate HIV vaccine candidates for safety, tolerability, and efficacy among TW, since TW represent <2% of HIV vaccine trials participants. This dearth of data on TW is likely to limit, or preclude, the uptake of a future approved HIV vaccine in the population that may benefit the most from it. Further, given TW's sensitivity to data quantity/quality, it is likely that the lack of early trials data about them impedes their willingness to enroll in other HIV vaccine trials phases. Thus, to increase TW's participation across all phases of HIV vaccine trials, we must first focus on increasing their recruitment and enrollment in Phase 1 trials. Recruiting and enrolling more TW in Phase 1 will generate more meaningful safety data on this population, which can be used to promote TW's participation in subsequent phases. Unfortunately, TW face multiple social and structural barriers to HIV vaccine trials participation, including stigma, discrimination, and transphobia (among others), all of which require large sociocultural changes to address. However, our formative work found a lack of tailored communication is also a critical, and more proximal, barrier to HIV vaccine trials engagement. For example, current efforts do not provide sufficient information on topics of concern to TW, nor do they offer information in a way that resonates with them. To intervene on this, we propose “VaxCom” a digital health communication tool to facilitate recruitment and enrollment of TW in Phase 1 HIV vaccine trials. We hypothesize VaxCom will improve recruitment and enrollment of TW into Phase 1 HIV vaccine trials by supporting discussions between recruitment and enrollment (R&E) specialists and TW regarding HIV vaccine questions/concerns, Phase 1 trials participation, and by providing relevant associated information to TW in a meaningful and tailored way. To develop VaxCom, we will first elicit TW's and R&E specialists' information needs and preferences for VaxCom. We will then incorporate them into an initial prototype of VaxCom that we further develop/refine alongside TW and R&E specialists through an iterative participatory design process. The resulting prototype will be evaluated for feasibility, acceptability, usability, and potential for success via simulated recruitment and enrollment sessions. The final product of this R21 will be an alpha prototype of VaxCom, which will be ready for pilot-testing in a future, R34-funded RCT.

NARRATIVE Evidence shows transgender women (TW) will only use biomedical HIV prevention strategies that have been rigorously assessed for safety, tolerability, and efficacy in this population, however, TW's participation in HIV vaccine trials is exceedingly low (<2% of trials participants), which will likely preclude their uptake of future vaccines. In response, the proposed R21 will develop and test a tailored digital health communication tool titled “VaxCom” to increase recruitment and enrollment of TW in Phase 1 vaccine trials by cuing discussions on TW's unique HIV vaccine questions/concerns, Phase 1 trials participation, and by presenting the associated information on these topics in a way that is targeted and meaningful to TW. Increasing TW's participation in Phase 1 HIV vaccine trials has the potential to generate meaningful TW-specific safety data, which can be leveraged to improve their participation in subsequent HIV vaccine trials phases.