FIG. 4. Longitudinal analysis of A, wild-type (WT) SpikĀ­e-receptor binding domain (S-RBD) IgG, B, WT surrogate virus neutralization test (sVNT) results, and C, Omicron BA.1 sVNT by vaccine type. Geometric means (GM) are shown with center lines and stated above each column. Limits of detection and quantification (LOD and LOQ) and cut-offs were drawn as grey lines. Data from participants receiving intradermal vaccination were shown as darkened squares beginning at their initial intradermal dose. Data from the same participant were analyzed longitudinally by paired t test after natural logarithmic transformation, and the P values are denoted by asterisks (*, P<0.05; **, P<0.01; ns, not significant).