Fig 5.

Immune response in study groups. Scatter plots display the median values and 95% confidence interval (CI; red line and bar) of serum IgM antibodies (A) and serum IgA antibodies (B). The participants are divided into six groups based on SARS‐CoV‐2 infection and/or vaccination: (i) unvaccinated naïve individuals (n = 88); (ii) unvaccinated convalescent individuals (n = 87); (iii) vaccinated naïve individuals (third dose; n = 11); (iv) vaccinated naïve individuals (third dose; n = 103); (v) vaccinated convalescent individuals (second dose; n = 104); and (vi) vaccinated convalescent individuals (third dose; n = 107). P < 0.05 was considered statistically significant by Kruskal–Wallis test followed by multiple comparisons with Dunn’s correction. The horizontal line represents the threshold for assay positivity (200 AU/mL for IgM and 100 AU/mL for IgA).