Figure 1.

IgG and IgA virus-binding activity in sera from individuals after repeated stimulation of the immune system with either natural and/or Gam-COVID-Vac vaccine SARS-CoV-2 antigens. Wu-1 S-protein-specific IgG and IgA levels were measured by ELISA and shown as binding antibody units (IgG) or coefficient of positivity (IgA). Comparisons show the fold change in median values (x5–x9). Statistical significance was determined using the Kruskal–Wallis test (* p < 0.1, ** p < 0.01, *** p < 0.001.