BACKGROUND and INTRODUCTION The Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) provides clinical trial sites to the International Maternal Pediatric Adolescent AIDS Clinical Trials Network (IMPAACT). The IMPAACT network is a cooperative group of institutions, investigators, and other collaborators focused on prevention and treatment of HIV infection and its related symptoms and co-infections in infants, children, adolescents and pregnant women. IMPAACT network activities are funded through Grants/Cooperative agreements sponsored by NIAID and co-funded by NICHD. The IMPAACT network and its leadership group, which includes NICHD, are responsible the creation of all their studies, protocols, and clinical trials. The IMPAACT Network goal is to conduct high quality clinical trials and/or protocols that advance the prevention and treatment of HIV and its complications for infants, children, adolescents, and pregnant/postpartum women globally. The IMPAACT research agenda includes four specific aims, which reflect its key areas of work. Those areas are HIV Treatment, HIV Prevention, HIV Cure, and HIV Complications. For each area, a Scientific Committee composed of experts in the specific field, site investigators, community representatives, and representatives of the central network resources, continually reassesses the research priorities in light of emerging science as well as new ideas and opportunities; seeks collaboration with other trials networks and research entities; oversees the formulation and review of study concept plans based on the scientific priorities; and monitors the development and implementation of approved network studies in its specific research area. NICHD collaboration with NIAID sponsored HIV research networks began in 1990, expanding clinical trial availability across NICHD funded clinical trial centers/sites. This collaboration helped make possible clinical trials by the IMPAACT Network to further evaluate antiretroviral therapeutic agents, other therapies targeted at opportunistic infections, and interventions to prevent perinatal HIV transmission. More recently the collaboration has expanded to evaluate potential HIV cure approaches and vaccines. In May 2019 the IMPAACT Network issued a Request for Proposals entitled “Investigations Needed for Future Clinical Trials and Secondary/Exploratory Study Objectives” with a primary purpose to encourage and support investigations that contribute to the knowledge base necessary for future clinical trials within the network’s research agenda. Investigators were invited to submit proposals for funding work that could be completed by 30 October 2020. That work must be 1) associated with secondary or exploratory study objectives specified in selected IMPAACT studies that closed to follow-up within the last five years and for which the primary analyses have been completed or 2) associated with completed non-network studies (with appropriate permissi...