This study looks at the safety and effectiveness of different drugs in treating COVID-19 in people who have been hospitalized with the infection and who have acute respiratory failure. Participants in the study will be treated with either a study drug plus current standard of care (SOC), or with placebo plus current SOC. Substudy H1: Aviptadil for Severely Ill Inpatients With COVID-19 (NCT06729606) Substudy H2: Remdesivir for Severely Ill Inpatients With COVID-19 (NCT06729593)

This is a master protocol to evaluate the safety and efficacy of investigational agents aimed at improving outcomes for patients with acute respiratory failure related to COVID-19. Trials within this protocol will be adaptive, randomized, blinded and initially placebo-controlled. Participants will receive standard of care (SOC) treatment as part of the protocol. If an investigational agent shows superiority over placebo, SOC for the study of future investigational agents may be modified accordingly. The international trials within this protocol will be conducted in up to several hundred clinical sites. Participating sites are affiliated with networks funded by the United States National Institutes of Health (NIH) and the US Department of Veterans Affairs. The protocol is for a Phase 3 platform study that allows investigational agents to be added and dropped during the course of the study. This allows for efficient testing of new agents against control within the same trial infrastructure. When more than one agent is being tested concurrently, participants may be randomly allocated across agents (as well as between the agent and its placebo) so the same control group can be shared, when feasible. In some situations, a factorial design may be used to study multiple agents. Participants will be followed for 90 days following randomization for the primary endpoint and most secondary endpoints. Selected secondary endpoints will be measured at 180 days. This study is planned to provide 80% power to detect an odds ratio of 1.5 for improvement in recovery status at Day 90 for an investigational agent versus placebo with use of the ordinal outcome. The planned sample size is 640 participants (320 per group) for each investigational agent/placebo. Sample size may be re-estimated before enrollment is complete based on an assessment of whether the pooled proportions of the outcome are still consistent with adequate power for the hypothesized difference measured by the odds ratio. Randomization will be stratified by study site pharmacy and by receipt of invasive mechanical ventilation, or ECMO (extracorporeal membrane oxygenation) at enrollment. Other agent-specific stratification factors may be considered. Investigational agents suitable for testing in the inpatient setting will be prioritized based on in vitro data, preclinical data, Phase 1 pharmacokinetic and safety data, and clinical data from completed and ongoing trials. In some cases, a vanguard cohort/initial pilot phase may be incorporated into the trial. An independent Data and Safety Monitoring Board (DSMB) will review interim safety and efficacy data at least monthly. Pre-specified guidelines will be established to recommend early stopping of the trial for evidence of harm or substantial efficacy. The DSMB may recommend discontinuation of an investigational agent if the risks are judged to outweigh the benefits.