Figure 2.

Extended immunization reduced serum neutralizing antibody responses

Pseudo-viruses neutralization curves for SARS-CoV-2 (wild-type) (A), Delta (B) and Omicron (C) strains by mice sera taken 10 days following the last dose of the conventional group or extended RBD vaccination. Comparison of neutralization titers between SARS-CoV-2 (wild-type) and two variant strains for the conventional and extended vaccine serum: the Wilcoxon matched-pairs signed rank test was used for the analysis and two-tailed p values was calculated; mean values were indicated above each column. Points represent individual mice in (A), (B) and (C). Data were presented as mean ± (SEM). Representative data of two independent experiments were shown. ∗p< 0.05, ∗∗p< 0.01. ns represented non-significant.