PROS1 and infection: Three B.1.1.7 S protein mutations are of particular concern: a two-amino-acid deletion at position 69–70 of the NTD; N501Y; and P681H, proximal to the furin cleavage site.45 Mutation P681H is a known region of importance for infection and transmission.28,46 The ∆H69/∆V70 deletion results in increased infectivity and evasion of the immune response.20 Beta variant known as multiple B.1.351 sublineages, includes nine mutations in S protein.