KIR2DL1, KIR2DL3, KIR3DL1 and KIR3DL2 (Figures 6G, S8C) are inhibitory NK cell receptors and enhanced interactions via these receptors on CD8+ T cells could indicate a more balanced functional regulation of CD8+ T cells in mild COVID-19. Here, KIR2DL1 is linked to COVID-19.