Fig. 4
Comparison of neutralizing antibody titers against Wild-type, Delta, and Omicron BA.1 strains
Shown are the NAb titers against the original Wild-type strain, the Delta variant, and the Omicron BA.1 variant as determined by the 50% focus reduction neutralization test (FRNT50). The bars indicate geometric mean titers, and I-shaped bars indicate its geometric standard deviations. The dushed horizontal lines indicate the LOD (NT50 titer < 40)
Statistical significance was determined by the GEE model (ns: not significant; *P < 0.05; **P < 0.01; ***P < 0.001)
Abbreviations: GEE, generalized estimating equation; LOD, limits of detection; NT50, m: months, 50% neutralization titer; 2 doses + 2 m, two months following the two doses; 2 doses + 8 m, eight months following the two doses; 95% CI, 95% confidence interval.