PROS1 and COVID-19: Using the strategy previously described and published [1] and summarized in Fig. 1a, we generated a cell-based secreted gp96-Ig vaccine (gp96-Ig-S) for COVID-19 by co-transfecting AD100 cells with plasmids encoding gp96-Ig and full-length protein S and selecting transfected cells with G418 and L-histidinol.