Figure 3

SARS-CoV-2 mRNA vaccine induced memory B cell responses. (a) The frequencies of circulating T follicular helper (cTfh) and circulating T peripheral helper (cTph) cells and naïve and memory B cells of peripheral blood mononuclear cells before (T0) and 1 week (T1), 2 months (T2), and 6 months (T3) after the 2nd dose of the BNT162b2 mRNA vaccine and 2 months after the 3rd dose of the vaccine (B-T2) are shown. (b) IgG⁺ memory B cells specific for the spike receptor-binding domain (RBD) of SARS-CoV-2 wild type and the Omicron variant induced by the BNT162b2 mRNA vaccine were analyzed by flow cytometry. The frequencies of wild-type and Omicron spike RBD-specific IgG⁺ cells among memory B cells at the indicated time points and (c) the association between these frequencies of wild-type and Omicron spike RBD-specific IgG⁺ at B-T2 are shown. Each dot indicates the value for one individual. Significant differences between groups were analyzed by the Friedman test. Correlations were analyzed using Spearman’s correlation analysis. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.