MKI67 and COVID-19: The percentages of proliferating CD4+ (Ki-67+) T cells in COVID-19+ samples showed an increasing trend with N peptide when compared to control, and the proliferating CD4+IFN-γ+ T cells in COVID-19+ samples responded after M-peptide stimulation when compared to control (Figure 2U,Y); notable differences were not observed within each group in IFN-γ-secreting CD4+ T cells or proliferating or IFN-γ-secreting CD8+ T cells following peptide stimulation (Figure 2V–X,Z).