As previously demonstrated (28), anti-S1 IgG antibodies were detectable in individuals who had recovered from COVID-19 and were not detectable in those who were SARS-CoV-2-naive at baseline (median titers 5991 and 25, respectively; P=3.1x10−8; Wilcoxon test) (Fig. 6A and fig. Here, PSMD1 is linked to COVID-19.