Abstract
Globally, HIV vaccine clinical trials are conducted in the quest for an effective preventive vaccine. Volunteers' participation is vital to the success of these trials. However, disclosing involvement in a vaccine trial may have significant consequences, potentially affecting key aspects such as recruitment, retention, and overall engagement. This study aimed to explore the experiences of disclosure and non-disclosure of participation in a Phase IIb HIV Vaccine Trial among female sex workers in Dar es Salaam, Tanzania, and used a descriptive qualitative design. Fifteen in-depth interviews and four focus group discussions were conducted among volunteers who were participating in the HIV vaccine trial. Data analysis was done manually using the framework method. Three themes emerged: reasons for disclosure, reasons for non-disclosure, and consequences of disclosure. Reasons for disclosure were grouped into two categories: intended disclosure and unintended disclosure. Intended disclosure occurred to seek support for trial participation and to share information within trusted relationships. Unintended disclosure arose from circumstances related to trial participation. Reasons for non-disclosure had two categories: perceived lack of understanding about trial participation and concerns about inadequate support. Consequences of disclosure encompassed three categories: uncertainty about the vaccine's side effects, the perception of volunteers being infected with HIV, and disapproval of the vaccine trial. The findings reveal that volunteers experienced a complex interplay between disclosure and non-disclosure of their participation in the PrEPVacc trial. The key themes - reasons for disclosure, non-disclosure, and consequences of disclosure - underscore the importance of understanding the personal and social factors influencing these decisions. These insights highlight the need for enhanced community education and support mechanisms to address concerns, mitigate misconceptions, and improve participation in HIV vaccine trials. Trial Registration: This study was conducted as part of a multicenter phase IIb three-arm, two-stage HIV prophylactic vaccine trial with Registration Number NCT04066881, accessible at https://clinicaltrials.gov/study/NCT04066881.