Fig.

3. Specific T-cell responses to vaccination with inactivated SARS-CoV-2 vaccine. PBMC from participants were isolated by density gradient centrifugation, and the treated PBMC were restimulated for 24 h with SARS-CoV-2 S defined peptide pool in the presence of Brefeldin A (during the last 8 h). T cells responses (Th1, Th2, Th17 and Treg) and intracellular cytokines (IL-2 and TNF-α) expressions were observed by intracellular staining. Samples were acquired on a flow cytometer and analyzed using FlowJo software. The results were presented as mean ± SEM (standard error of the mean). N = 15, *P < 0.05, **P < 0.01.