IFNG and COVID-19: IFN-γ spots produced by SARS-CoV-2 antigen-specific T-cells were significantly increased by the stimulations of SARS-CoV-2 specific S1, S2, and N antigen peptides in the COVID-19 group compared to those in the HC group (Fig. 2B, P= 0.0032, 0.0020, 0.0012, respectively).