Fig. 1

SARS-CoV-2 specific antibodies in COVID-19 severe cases and non-severe cases. Serum samples from severe cases (n = 48) and non-severe cases (n = 71) were compared for SARS-CoV-2 S specific antibody isotypes: IgG, IgA, and IgM (a), different anti-S IgG subtypes (IgG1, IgG2, IgG3, and IgG4) (b), IgG titers targeting S, RBD, RBM, NTD, and CTD (c), IgA and IgM response targeting RBD, NTD, and CTD (d). The OD₄₅₀ values were normalized by subtracting OD₆₅₀ values. The antibody titers were the dilution fold that reached half-maximal binding with corresponding antigens, and the values were calculated by Graphpad Prism 9. Mann–Whitney U test was used to compare differences between the two groups. Significances were marked as follows: P < 0.05 (*), P < 0.01(**), P < 0.001 (***), and P < 0.0001 (****), respectively. Abbreviations: S: Spike; RBD: Receptor Binding Domain; NTD: N-terminal Domain; CTD: C-terminal Domain