Fig. 1

SARS-CoV-2 spike S1-specific total IgG levels in younger and older adults following mRNA vaccination. A Schematic overview of the vaccination and sampling scheme in which participants received original monovalent (1st to 4th dose) and bivalent (5th dose) mRNA vaccines. SARS-CoV-2 spike S1-specific total IgG concentrations (BAU/mL) following mRNA vaccination were measured in serum by multiplex immunoassay for B older adults (n = 50) up to one month after the fifth vaccination and for C younger (n = 64) and older (n = 50) adults up to approximately one month after the third vaccination. Dotted lines indicate the cut-off for seropositivity. SARS-CoV-2-infected individuals (based on N seropositivity) are indicated with open circles. Differences between groups were assessed using a non-parametric (unpaired) Wilcoxon signed rank test with Bonferroni’s correction for multiple testing. *** P < 0.001; **** P < 0.0001. BAU, binding antibody units; N, nucleoprotein; ns, not significant