The nine biological molecules associated with both mild and severe COVID-19 included receptors, namely androgen receptor (AR), nuclear receptor subfamily 3 group C member 1 (NR3C1)/glucocorticoid receptor, NR3C2/mineralocorticoid receptor, toll-like receptor (TLR)7 and TLR9; cytokine/chemokines, namely C-C motif chemokine ligand 5 (CCL5); signaling mediators, namely Janus Kinase 1 (JAK1); and enzymes, namely phosphodiesterase 5A (PDE5A) and cytochrome P450 oxidoreductase (POR). The gene discussed is PDE5A; the disease is COVID-19.