Thus, with its pan-CoV fusion and entry inhibitory activity by targeting two sites in S protein, desirable half-life, and promising oral bioavailability, S-20-1 is a potential candidate for further development as a novel therapeutic and prophylactic drug against infection by SARS-CoV-2 and its variants, as well as future emerging and reemerging CoVs. Here, PROS1 is linked to infection.