TLR3 and COVID-19: To this end, PBMCs isolated from COVID-19 patients before receiving their first dose of dexamethasone, were exposed ex vivo to heat-inactivated SARS-CoV-2, heat-inactivated H1N1 Influenza, heat-inactivated S. aureus, the TLR4 ligand LPS, the TLR3 ligand poly I:C, the TLR7 ligand imiquimod, the TLR7/8 ligand R848, or the tissue damage-related cytokine IL-1α in the presence or absence of dexamethasone.