PROS1 and viral infectious disease: Preliminary phase 1 trial results showed no severe adverse events and the triggering of multiple immune responses against SARS-CoV-2 antigens: a CD8+ cytotoxic T-cell response to the viral S protein that is necessary for long-lasting cross-reactive immunity, an increase in plasmablast cell numbers and an upregulation of the mucosal homing receptor, an increase in proinflammatory Th1 cytokines responsible for orchestrating the immune response to viral infection, and an IgA response in serum and/or nasal swab samples in 100% of the two-dose subjects [88,89].