Fig. 2: Temporal dynamics of anti-SARS-CoV-2 T cell immunity in vaccinated participants.

SARS-CoV-2 S-reactive CD4⁺ and CD8⁺ T cells after in vitro stimulation with SARS-CoV-2 S-I and S-II peptide pools and nucleoprotein peptide pool. a, Representative dot plots from four vaccinated individuals, 28 days after the second dose of the vaccine, showing the percentage of double-positive cells expressing HLA-DR and CD38 out of CD4⁺ T cells (top) and CD8⁺ T cells (bottom). Individuals who were previously infected to SARS-CoV-2 or uninfected are indicated by blue or purple shades, respectively. b, The percentage of double-positive cells, spike-reactive and nucleocapsid-reactive out of CD4⁺ T cells (top) and CD8⁺ T cells (bottom) over time post-vaccination. Individuals who were previously infected to SARS-CoV-2 or uninfected are indicated by blue or purple dots, respectively. Each dot represents a single individual. Significance was assessed by one-way ANOVA corrected for multiple comparisons using Dunnett’s method. Vaccination time points were compared with baseline. Stimulation values were subtracted from the respective non-stimulation condition. The bars represent the distribution of variables with quartiles and outliers. The horizontal bars indicate mean values. TP 0: n = 30; TP 1: n = 34; TP 2: n = 27; TP 3: n = 27; TP 4: n = 24). Non-stim, non-stimulated PBMCs; nucleocapsid, PBMCs stimulated with the SARS-CoV-2 nucleocapsid protein pool derived from the ancestral lineage A virus, WA1, USA; spike, PBMCs stimulated with the SARS-CoV-2 spike protein pool derived from the ancestral strain lineage A, WA1, USA; spike (P.1), PBMCs stimulated with the SARS-CoV-2 spike protein pool derived from the P.1 variant. ****P < 0.0001, ***P < 0.001 and **P < 0.01.