PROS1 and COVID-19: Antibodies targeting RBD, S proteins, NP of SARS-CoV-2, SARS-CoV-1 and human coronaviruses (229E, NL63, OC43, HKU1) along with isotypes/subclasses (IgM, IgG, IgG1–4, IgA1–2), binding with FcgR (FcgR2aH, FcgR2aR, FcgR2b, FcgR3aV, FcgR3aF) and C1q, totaling 315 features, were assessed in 14 COVID-19 and 5 non-COVID-19 respiratory samples, and paired plasma.