Fig. 1: Comparison of neutralizing activity among I-I-δ, I-I-ο, M-M-ο, and I-I-I groups.

a Neutralizing response against WT SARS-CoV-2 and VOCs, including Delta and Omicron variants. The numbers in magenta indicated the geometric mean titers (GMTs), and fold change in GMT for the virus compared with the strain with lower neutralizing titer. b Comparison of NAb titers based on the monoclonal antibodies 13G2 and 08B3 among I-I-δ, I-I-ο, M-M-ο, and I-I-I groups. c–h Correlation of NAbs against the WT and the Delta and Omicron variants and levels of the monoclonal antibody 13G2 among I-I-δ, I-I-ο, M-M-ο and I-I-I groups. Significance was measured using the Mann–Whitney tests. *P < 0.05, **P < 0.01, ***P < 0.001. I-I-δ, Delta infection after two-dose inactivated vaccine (n = 34); I-I-o, Omicron infection after two-dose inactivated vaccine (n = 22); M-M-o, Omicron infection after two-dose mRNA vaccination (n = 9); I-I-I, three-dose inactivated vaccine (n = 40).