"I have the vaccine in my body": perceptions of female sex workers after enrolling in a phase IIb HIV vaccine and pre-exposure prophylaxis trial in urban Tanzania.

BACKGROUND: HIV continues to be a significant global public health problem in low and middle-income countries. Efforts to search for an effective and affordable preventative HIV vaccine are on-going. We investigated the understanding of perceived risk for acquiring HIV and the experience of female sex workers (FSW) in Tanzania, before and after enrolling in an HIV vaccine and Pre-Exposure Prophylaxis Trial. METHODS: This was a descriptive qualitative study design nested in a multicentre Phase IIb three-arm, two-stage HIV prophylactic vaccine trial with a second randomization to compare two pre-exposure prophylaxes (PrEPVacc trial) regimens. We present findings from Dar es Salaam site in Tanzania. Fifteen in-depth interviews and four focus group discussions were conducted among FSW who participated in the HIV vaccine and Pre-Exposure Prophylaxis Trial between 2021 and 2023. Data analysis was done manually using the Framework and thematic content analysis approaches. RESULTS: Two themes emerged from the findings: `Apparent risk' of acquiring HIV infection before enrolling in the HIV vaccine trial and `Balancing perceived risk' of acquiring HIV infection and preventive measures after enrolling in the HIV Vaccine and Pre-Exposure Prophylaxis Trial. Before enrolling in the trial, the participants perceived themselves at high risk of acquiring HIV infection. They reported inconsistent condom use in multiple relationships with clients whose HIV status was unknown. After enrolling in the trial, the participants reported improved knowledge of HIV prevention, particularly the use of pre-exposure prophylaxis and compliance with preventive measures. However, some participants perceived that the experimental vaccine was an established HIV preventive measure. In addition, condomless sex was still practiced, mainly to get higher payments from the clients. CONCLUSION AND RECOMMENDATIONS: The knowledge gained on HIV preventive measures by FSW after participation in the trial was valued. However, continued engagement in risky sexual practices and poor compliance with HIV preventive measures highlights the need for continued risk-reduction interventions while searching for an effective HIV vaccine.