FIG 5.

Quantification of circulating neutralizing antibodies and AIM⁺ CD4⁺ T cells against SARS-CoV-2 variants Delta and Omicron in participants that received two doses of CoronaVac. (A) Neutralizing antibodies were detected in the plasma of 88 participants 4 weeks after the second dose of CoronaVac, using a pseudotyped virus neutralization test (pVNT). Data are expressed as the reciprocal of the highest dilution preventing 80% of the infection (ID₈₀). Numbers above the bars show the GMT, and the error bars indicate the 95% CI. (B) Neutralizing antibody levels between 52 participants in the 3- to 11-year age group and 36 participants in the 12- to 17-year age group against D614G, Delta, and Omicron variants are shown. (C and D) AIM⁺ CD4⁺ T cells against the variants Delta and Omicron were measured by flow cytometry. (C) Results were obtained from a total of 59 participants. (D) Results shown by age group (29 participants from the 3- to 11-year age group and 30 participants from the 12- to 17-year age group). The numbers in red (decrease) or blue (increase) next to the statistics show the fold change of the response against the variant relative to the WT or D614G strain. (E) The correlations between neutralizing antibody titers and AIM⁺ percentages against the Omicron variant were evaluated. The Pearson correlation coefficient (r) and the P value are indicated in each scatterplot. A one-way ANOVA followed by Dunnett’s multiple-comparison test (A and C) and two-way ANOVA followed by Šídák’s multiple-comparison test (B and D) were performed to assess differences. *, P < 0.05; ***, P < 0.001; n.s., nonsignificant.