Clearly, the ACE I/D polymorphism showed a significant relationship with the severity of COVID-19 (Figure 3 and Table 4, D vs. I: OR = 1.64, 95% CI = 1.01–2.66; DD vs. II: OR = 4.62, 95% CI = 2.57–8.30; DI vs. II: OR = 3.07, 95% CI = 1.75–5.38; dominant model: OR = 3.74, 95% CI = 2.15–6.50; and recessive model: OR = 1.28, 95% CI = 0.46–3.51). The gene discussed is ACE; the disease is COVID-19.