 The study aims to evaluate the effectiveness of a mobile phone-based intervention, interactive transition support for adolescents living with HIV using social media, in TSA, in improving retention in care and viral suppression among adolescents living with peronately acquired HIV as they transition from pediatric to adult care in South Africa. The intervention uses encrypted, closed group chats delivered via WhatsApp to develop peer support and improve communication between adolescents, their caregivers, and healthcare providers. The study will randomly assign 80 South African adolescents living with peronately acquired HIV, who are aware of their HIV status, and aged between 15, and 19 years to receive either the intervention or standard of care. The primary outcome is acceptability of the intervention, while secondary outcomes include retention in care and viral suppression, peer support, self-esteem, depression, stigma, sexual education, connection to healthcare providers, and transition readiness. Enrollment began on April 15, 2021, and a total of 78 out of expected 80 participants have been enrolled as of December 31, 2021. If successful, the intervention will be evaluated in a fully-powered randomized controlled trial with a larger number of adolescents from urban and rural populations to further evaluate its generalizability. This article was authored by Brian Cisinoni, Mohundran Arkery, Thope Kyle Sabaya, and others. We are article.tv, links in the description below.