Adapt Out COVID is a master protocol to evaluate the safety and efficacy of investigational agents for the treatment of symptomatic non-hospitalized adults with SARS-CoV-2 infection. It includes a Phase II evaluation, with a seamless transition into a larger Phase III evaluation for promising agents. The trial is a randomized, controlled platform that allows agents to be added and dropped during the course of the study for efficient testing of new agents against placebo within the same trial infrastructure. When more than one new agent is being tested concurrently, the same placebo will be used, when feasible. The primary outcome measures in the Phase II evaluation will be duration of symptoms, similar to the outcome used for outpatient influenza studies, detection of SARS-CoV-2 RNA by nasopharyngeal (NP) swab, and safety. Determination of whether a Phase II agent will continue to be evaluation in Phase III will be made after the last participant randomized to that agent or placebo completes their day 28 Phase II visit. If continued, data collected from participants enrolled in Phase II will be included in the Phase III evaluation. The Phase III evaluation is a continuation of the Phase II trial, for those agents that meet criteria for further evaluation and for which sufficient study product is available. Enrollment of those agents advancing to Phase III will continue for a fully powered trial to determine the efficacy of each investigational agent compared to placebo to prevent hospitalization and death in non-hospitalized adults with COVID-19. 1. The ACTG Leadership and Operations Center (LOC). A newly restructured LOC is proposed to provide scientific leadership and fiscal and organizational management of the ACTG. The ACTG Executive Committee (AEC) will serve as the overarching governing body of the network. Transformative Science Groups will oversee the development and execution of the ACTG research agenda, which will be coordinated and prioritized by the Scientific Agenda Steering Committee (SASC). Protocol development, implementation, training and network evaluation will be facilitated by the Network Coordinating Center at Social & Scientific Systems, Inc. The LOC financial management group at Brigham and Women's Hospital (BWH) will oversee resource management and protocol fund distribution at the direction of the AEC. The LOC will assure the engagement of Community in all aspects of the ACTG, and will coordinate communication between all three components of the network. 2. The ACTG Laboratory Center (LC). The ACTG LC will comprise Specialty Laboratories in virology, immunology, pharmacology, mycobacteriology and genomics equipped to perform protocol-specified testing and to advance the state-of-the-art by developing novel assays to address innovative pathogenesis-based questions arising from ACTG clinical trials. The LC will also oversee the quality management of all laboratories performing testing for clinical monitoring a...