Abstract
Despite significant progress in global HIV prevention, adolescent girls and young women in sub-Saharan Africa remain disproportionately affected, with high rates of new infections persisting. This study explored the acceptability of subcutaneously administered broadly neutralising antibodies, receiving either one or two doses of VRC07-523LS and/or PGT121, from the perspective of women living without HIV in KwaZulu-Natal, South Africa. This qualitative sub-study explored the motivational, capability, and opportunity factors influencing product acceptability through in-depth interviews with 26 of the 45 participants aged 18-45 years who participated in the CAPRISA 012A Phase 1 trial. Thematic analysis guided by the COM-B Model and Theoretical Framework of Acceptability were used to explore the acceptability of products. Clear communication about potential side effects, study coherence and product attributes such as longer-acting, injectable delivery facilitate high acceptability. External factors including lack of social support and fear of stigma affected decision-making, with intrinsic motivation and self-efficacy beliefs about using the product emerging as critical determinants of product use. While most participants disclosed study participation to partners and family, partner influence varied; participants reported having the product administered based on personal health concerns regardless of partner support. Access to additional sexual and reproductive health services through study participation further enhanced acceptability of study product. The findings underscore the importance of integrating clear messaging on product efficacy, linking potential HIV prevention products to broader healthcare services, and supporting different users to make the decision to use this product. This study provides a novel contribution to understanding the complex dynamics of acceptability and behaviour change, essential for successful implementation and uptake of HIV prevention strategies.