Fig. 1: Analysis of the antibody response profile at the time of first vaccination (T0), second vaccination (T1), and 3 weeks after the boost (T2) in naïve and previously infected (P.I.) recipients.

Median values with the interquartile range are displayed. The horizontal dot lines indicate the cutoff value to discriminate positive and negative samples for each assay, according to the manufacturer’s instructions. a IgG for the SARS-CoV-2 nucleocapsid protein N (sample sizes: T0 n = 48, T1 n = 50, T2 n = 49 for naïve, T0 and T1 n = 51, T2 n = 49 for P.I.); b IgM for the spike glycoprotein (sample sizes: T0 n = 48, T1 n = 50, T2 n = 49 for naïve, T0 and T1 n = 51, T2 n = 49 for P.I.); c IgA for the spike glycoprotein (sample sizes: T0 n = 49, T1 n = 50, T2 n = 49 for naïve, T0 and T1 n = 51, T2 n = 49 for P.I.); d IgG for the receptor-binding domain (RBD) of the spike (sample sizes: T0 n = 48, T1 n = 50, T2 n = 49 for naïve, T0 and T1 n = 51, T2 n = 49 for P.I); e pseudoviruses neutralization assay, expressed as infectious dose (ID50) (sample sizes: T0 n = 48, T1 n = 50, T2 n = 49 for naïve, T0 and T1 n = 51, T2 n = 50 for P.I.). P values were calculated using the nonparametric two-tailed Wilcoxon matched-pairs signed-rank test for within-group comparisons (bars on top) and the nonparametric Kruskal–Wallis test for between-groups comparisons (bars on bottom). Differences were considered significant if p < 0.05.