Figure 4.

Phase 2 quantitative variables of global immunogenicity by study groups and days.

Panel A: anti-RBD IgG antibody titers. Panel B: Inhibition of RBD-ACE-2 binding. Panel C: Neutralizing antibody titers. The study groups are represented by colors, red for RBD 25 µg, blue for RBD 50 µg and gray for placebo. The boxes and horizontal bars indicate interquartile range (IQR) and the median, respectively. The whisker's end points are the maximum and minimum values below or above the median ± 1•5 times the IQR. Points represent possible outliers. The braces contain the results of the Mann Whitney U multiple comparison tests with Bonferroni correction. For the viral neutralization variable, Student's t tests were used to compare geometric means. Only p values for significant differences are shown. The bottom row shows the scatter graphs and the line adjusted by least squares by study group (red for RBD 25 µg, blue for RBD 50 µg) of the values corresponding to day 56. In each case, Pearson's correlation coefficient and the associated p-value are included. RBD: receptor binding domain. ACE-2: angiotensin-converting enzyme. AU/mL: arbitrary units per mL. Nab: Neutralizing antibody titers.