This analysis revealed that interactions between monocytes and NK cells in severe COVID-19 were predicted to upregulate genes involved in NK cell cytotoxicity [GZMB (48), PRF1 (49), LGALS1 (50), TNFSF10 (51)], proliferation [MCM6 (52), KNTC1 (53)], apoptosis [ANXA2 (54), ANXA5 (54), BAX (55), FAS (56), CASP1 (57), PML (58)], cellular adhesion [STMN1 (59), VCAN (35)], and migration [CX3CR1 (60)]. Here, PRF1 is linked to COVID-19.