Project Summary Our program, “Preventing Infant Infection with Implementation Science in Malawi”, PRI3SM, will conduct 3 clinical studies to address incident maternal HIV infections during pregnancy and breastfeeding and (re)engage pregnant and breastfeeding women with HIV frequently missed by traditional HIV care. Our research projects will be supported by an Administrative Core, an Implementation Science Core and a Data Science and Analytical Core. Our accumulated experience with EMTCT research in Malawi since 2002; established local partnerships; cross disciplinary expertise in clinical research, epidemiology, implementation and behavior science; and our synergistic projects put us in a superb position to impact MTCT by addressing the following aims: Aim 1. (Research Program) Conduct 3 synergistic research projects focused on addressing gaps in the EMTCT cascade that collectively expand HIV treatment and prevention in pregnancy and postpartum to avert maternal and infant infections.Aim 1a. Project 1 (PrEP in Pregnancy) To evaluate maternal and infant safety of PrEP regimens in pregnancy and breastfeeding. Cabotegravir (CAB) injectable PrEP represents a substantial advance over daily oral PrEP7 and could dramatically reduce new maternal infections. But CAB has not been systematically studied in pregnant and lactating women. We will establish a national registry of CAB and TDF/FTC PrEP users who become pregnant alongside a safety cohort of pregnant women receiving PrEP to compare pregnancy and infant outcomes. Aim 1b. Project 2 (Postpartum Prevention Package) To optimize post-partum HIV prevention including PrEP uptake and persistence among at-risk lactating women to prevent primary HIV infection and subsequent infant infection using a novel integrated task-shifting intervention strategy including partner engagement and testing, PrEP, and community outreach. Aim 1c. Project 3 (PAC-Man) To evaluate reach and effectiveness of a novel community-based service model, the “Point-of-care (POC) Active Case-finding & Management” (or PAC-Man) model to identify and test infants missed through routine facility testing and determine effectiveness and measure implementation outcomes including, adoption, implementation, sustainability, and cost per pediatric HIV case identified. AIM 2. (Admin Core) Create a robust administrative structure to implement and integrate research protocols efficiently and effectively, support the Implementation Science and Data Science and Analytical Cores, and nurture existing rich partnerships with the sponsor, Ministry of Health and HIV PEPFAR implementing partners. Aim 3. (Support Cores) To establish robust Implementation Science and Data Science and Analytical Cores to provide support to the study projects, support Ministry of Health program evaluation, and facilitate engagement of early-stage investigators through existing D43 capacity building programs. Broadly, we expect to identify successful implementation strategies with ...