PROS1 and COVID-19: The printed S protein variants were selected containing mutations from the COVID-19 virus mutation tracker database 21 (Figure S2) and literature 22, 23, and included 2 variants with mutations in the S protein's subunit 1 (S1) and subunit 2 (S2) domains, 7 variants with mutations in S1, and 63 variants with mutations in the RBD 21.