T-cell restrictions of SARS-CoV-2 epitopes. Identification of the T cells responding to each identified epitope was performed via intracellular cytokine staining on expanded CSTs, with percentages of TNF-a⁺/IFN-γ⁺ populations depicted. Intracellular cytokine staining demonstrated a predominant CD4-mediated response to membrane peptides 37-38 (A), membrane peptides 44-45 (B), nucleocapsid peptide 65 (C), and spike proteins 15-16 (D), and a predominant CD8-mediated response to nucleocapsid peptide 81 (E). SEB, staphylococcal enterotoxin β.