Fig. 1

Prime-boost vaccination elicited RBD-specific CD4⁺T and CD8⁺T cells. A Experimental design for AIM. B Representative flow cytometry plots for RBD-specific CD4 (left) and CD8⁺T cell (right) after stimulation of PBMCs with RBD protein, gated on CD3⁺CD4⁺T cells. The scatter in the frame represented the frequency of AIM⁺CD4 and CD8⁺T. C Proportions of AIM⁺CD4 (left) and CD8⁺T (right). responder (resp) cut-off is 0.84 (AIM⁺CD4) and 0.80 (AIM⁺CD8) (dotted line). *: P < 0.05, **: P < 0.01, ***: P < 0.001, ns: no significance. Significant difference was calculated by Kruskal–Wallis’s test