Phase 2a: Adverse events of XAV-19;Phase 2a: XAV-19 antibody titers;Phase 2b: To evaluate the efficacy of XAV-19 + standard-of-care (Soc) therapy compared with placebo + Soc therapy for treatment of COVID-19 assessed by the proportion of patients who die or develop respiratory failure between baseline and Day 15.

Phase 2a: Adverse events of XAV-19;Phase 2a: XAV-19 antibody titers;Phase 2b: To evaluate the efficacy of XAV-19 + standard-of-care (Soc) therapy compared with placebo + Soc therapy for treatment of COVID-19 assessed by the proportion of patients who die or develop respiratory failure between baseline and Day 15.

Phase 2a: Adverse events of XAV-19;Phase 2a: XAV-19 antibody titers;Phase 2b: Time to weaning of supplemental oxygen.

Phase 2a: Adverse events of XAV-19;Phase 2a: XAV-19 antibody titers;Phase 2b: Time to weaning of supplemental oxygen.