KRT18 and infection: Conversely, K18-hACE2 mice receiving 7A3 VHH-hFc fusion protein or the 2-in-1 mixture of 7A3 and 8A2 at a dose of 5 mg/kg had 100% survival after lethal B.1.351 infection, with no BW drop within the 2-wk observation period (Fig. 4 B, Left).