In an important follow-up study deposited in July 2020, where Wettstein et al. produced SARS-CoV-2 S-protein pseudoparticles and performed in vitro infection of Caco2 cells in the presence of chromatographically fractioned bronchoalveolar lavage samples they found that the highest inhibition of infection occurred in the fraction containing A1AT (229). Here, PROS1 is linked to infection.