CD4 and infection: As a surrogate of SARS-CoV-2 antigen after infection, we used peptides covering the immunodominant sequence domains of the SARS-CoV-2 Spike (Peptivator peptide pool [Miltenyi]) to stimulate CD14-depleted PBMCs and measure IFNγ+ and CD107a+ frequencies in both CD4+ and CD8+ primary T cells.