CD40LG and infection: Potential exploratory outcome measures may include: changes from baseline (day 1) in laboratory measures, specific biomarkers of infection, serology, inflammation (eg, D-dimer, lipocalin, cytokines, IgM/IgG sero-conversion, and neutralization assays), and viral load in outpatients with mild to moderate COVID-19 in the presence and absence of KB109.<h4>Randomisation</h4>All patients deemed eligible for the studies will be randomized in a 1:1 ratio to KB109 in addition to SSC or SSC alone group using an interactive response technology system.