To evaluate the efficacy; safety and tolerability of ADG20 <br/ >compared to placebo in the treatment of mild <br/ >or moderate COVID-19 in participants at <br/ >high risk of disease progressionTimepoint: The efficacy of ADG20 will be assessed through Day 29 with endpoints of COVID-19-related hospitalization or all-cause death. <br/ >The safety and tolerability of ADG20 will be assessed through Day 29 based on : <br/ >-The incidence of TEAEs <br/ >-Incidence of solicited injection site reactions through Day 4 <br/ >- Changes from baseline in clinical laboratory tests <br/ >- Changes from baseline in vital signs

To evaluate the efficacy; safety and tolerability of ADG20 <br/ >compared to placebo in the treatment of mild <br/ >or moderate COVID-19 in participants at <br/ >high risk of disease progressionTimepoint: The efficacy of ADG20 will be assessed through Day 29 with endpoints of COVID-19-related hospitalization or all-cause death. <br/ >The safety and tolerability of ADG20 will be assessed through Day 29 based on : <br/ >-The incidence of TEAEs <br/ >-Incidence of solicited injection site reactions through Day 4 <br/ >- Changes from baseline in clinical laboratory tests <br/ >- Changes from baseline in vital signs