Fig. 4: Evaluation of anti-SARS-CoV-2 IgG binding activity in mRNA vaccinee sera (pre- and post-booster).

Each dot represents calculated IgG concentration (BAU/mL or AU/mL) of an individual serum sample against a specific protein antigen. The geometric mean IgG concentrations (avg. BAU/mL or AU/mL) from pre- and post-booster sera are shown on the top of the graph. For statistical analysis, a two-tailed Wilcoxon matched-pairs signed-rank test was performed by comparing antibody concentration of pre- and post-booster sera. Test statistics and P value are summarized in Supplementary Table 2. Source data are provided as a Source Data file. a IgG antibodies specific to SARS-CoV-2 nucleocapsid (N), receptor binding domain (RBD) and spike(S) were measured. N = 18–20 biologically independent pre-booster sera (light blue) and N = 18–20 biologically independent post-booster sera (dark blue). The average IgG concentrations in all post-booster sera differ significantly (P < 0.0001) from the pre-booster sera, except those specific to the nucleocapsid (P = 0.1084). Dashed line represents the limit of quantification for the N protein. LOQ = 11.8. b IgG antibodies specific to SARS-CoV-2 spike proteins of 6 different viruses were measured. N = 17–20 biologically independent pre-booster sera (light blue) and N = 17–20 biologically independent post-booster sera (dark blue). The average IgG concentrations in all post-booster sera differ significantly (P < 0.0001) from the pre-booster sera. BAU: binding antibody units calibrated to WHO international standard. AU arbitrary units.