PROJECT SUMMARY Impressive progress has been made towards the ambitious goal of eliminating mother to child transmission (EMTCT) globally. In efficient EMTCT programs with high rates of ART uptake, an increasing proportion of new infant infections stem from incident maternal infections; in sub-Saharan Africa nearly one third of infant transmissions are linked to HIV infections that are acquired during pregnancy or breastfeeding. Driven by physiological shifts and behavioral changes, including resumption of condomless intercourse, the postpartum period is a particularly high-risk period for HIV acquisition. In Malawi, one-third of all new pediatric HIV infections are attributed to women who acquired HIV infection while breastfeeding. Improved postpartum HIV prevention is needed to prevent pediatric infections. One promising HIV prevention opportunity is HIV pre- exposure prophylaxis (PrEP). Taken as prescribed, daily oral PrEP effectively prevents HIV and is safe during breastfeeding. Unfortunately, uptake of and adequate adherence to PrEP among postpartum women in sub- Saharan Africa, including in Malawi, has been poor. Newer long-acting PrEP formulations, including injectable PrEP, is a promising and potentially paradigm shifting advance for HIV prevention, offering more discrete and convenient dosing. However, to maximize the prevention potential of PrEP (oral, injectable, or other), programs must address shortfalls across the prevention cascade –increasing rates of postpartum HIV testing, reducing barriers to PrEP initiation, and improving retention in PrEP care by tracing defaulters. This study will test an intervention that mobilizes an integrated, task-shifting strategy to improve effective PrEP use among postpartum women in Malawi. Leveraging maternal attendance at early infant vaccination visits, the integrated intervention deploys effective strategies to increase HIV testing, promote partner engagement, enhance access to oral or injectable PrEP, and retain women in PrEP care. The intervention uses task-shifting to integrate HIV testing and PrEP services into infant vaccination visits, and builds on the highly-effective community-facility linkage model “peers”, expanding tracing to include PrEP defaulters. In Aim 1, investigators evaluate the effectiveness the integrated “postpartum prevention package” intervention, examining primary outcome of PrEP persistence at 12 months among breastfeeding women. Secondary outcomes include PrEP uptake, PrEP adherence, and seroconversions. Aim 2 focuses on implementation outcomes, examining fidelity to and acceptability of the integrated intervention among postpartum women, a subset of their male partners, clinic providers, and policymakers. In Aim 3 investigators conduct a cost-effectiveness analysis using effectiveness outcomes and prospectively collected costs, modelling cost per new PrEP initiation and per person retained on PrEP. A budget impact analysis identifies drivers of cost, informing Minis...