Figure 3. Cellular immune responses to SARS-CoV-2 in vaccinated 2-year convalescents detected by ELISpot.
A, Cross-sectional T cell responses to the Wild type (WT) overlapping peptide pools encompassing the S1, S2, N, and M proteins, which were detected using IFN-γ ELISpot assay in vaccinated 2-year convalescents (2Y-Vac, n=51) and vaccinated healthy controls without prior infection (HC-Vac, n=35). B-C, The magnitude of T cell responses in HC-Vac (blue, n=35) and 2Y-Vac (red, n=51) groups. Freshly isolated PBMCs (B) and cultured PBMCs (C) after 9 days ofin vitro expansion were stimulated with one of four peptide pools (S1, S2, M, and N). D-E, Comparison of the magnitude of T cell responses in Asym-Mild (Asymptomatic and Mild, pink, n=25) and Mod-Sev (Moderate and Severe, dark green, n=26) convalescents for ex vivo (D) andin vitro experiments (E). F, The proportion of positive T cell responses in 2Y-Vac and HC-Vac individuals found in nil (0 response, white), one (1 response, pink), two (2 response, red), three (3 response, orange), or four (4 response, reseda) peptide pools. Each dot reflects an individual donor. The solid lines represent the mean ± SEM. Statistical significance was performed with a Mann-Whitney U-test (B-E). * p < 0.05, ** p < 0.01, *** p < 0.001.