Fig. 3.

Comparison of humoral immune responses after the second and third doses. Anti-severe acute respiratory syndrome coronavirus 2 spike protein immunoglobulin G antibody titers are presented at baseline (T1), 4 weeks (T2), and 5 months (T4) after the second dose and baseline (T4), 4 weeks (T5), and 5 months (T7) after the third dose. Error bar depicts median with interquartile range. The dashed line represents the antibody positivity threshold, indicating 0.8 U/mL. At the bottom, the elapsed average time since the first dose (days), the number of participants sampled, and the geometric mean antibody titer at each time point are presented. ***P < 0.001.