“Getting involved”: understanding informal practices, challenges and alternatives in assisted partner notification services for HIV in Cape Town, South Africa

South Africa has the world's highest HIV burden. Assisted partner notification (APN) has been shown to improve HIV testing uptake and case finding, yet little is known about its implementation in contexts where gender inequalities, stigma and complex relationship dynamics shape disclosure. This qualitative study explored implementation experiences of APN services among healthcare providers and patients in Cape Town. Between March 2021 and February 2022, we conducted semi-structured interviews, WhatsApp diary studies and fieldwork observations with 34 participants, including 10 healthcare providers, 12 female patients and 12 key informants. Data were analyzed using thematic analysis. Findings revealed significant disconnect between formal APN protocols and clinical practice. Despite official guidelines emphasizing voluntary participation, informal practices termed "getting involved" emerged where providers engaged in unstructured assistance with partner notification. Key challenges included compromised voluntary participation, coercive tactics, communication barriers and concerns about social harm and privacy breaches. In response, providers and patients developed alternative strategies, notably "collusion-testing" and reliance on informal "assistants" from personal support networks. APN processes and safeguards should be more clearly outlined in HIV testing policies, with greater provider training to reduce coercive practices and better integrate community support systems.