ACE2 and infection: The second mutation, a leucine to arginine change at position 452 increases the affinity for ACE2 receptor and the third, a threonine to lysine substitution at position 478, is common to the B.1.1.519 lineage, and it has been also predicted to increase RBD/ACE2 binding affinity and enable immune escape [54]. In addition, a proline to arginine substitution is present at position 681 adjacent to the furin cleavage site of the Spike protein that increases the efficiency of its cleavage to mediate viral fusion and initiate infection.