IFNB1 and severe acute respiratory syndrome: While the efficacy of IFN-λs against SARS-CoV replication, when used alone or in combination with IFN-β, has been consistently observed in our studies, additional in vitro and animal studies are warranted to determine the mechanism(s) of protection and whether type I and type III IFNs exert a redundant, complementary, or synergistic role in the host defense against SARS-CoV infection.