Furthermore, multivariate Cox regression analysis revealed that a significant decrease in CD8+ T cell count in peripheral blood was independently associated with composite outcome in COVID-19 patients treated with Nirmatrelvir, with an HR of 2.01 (95%CI: 1.03-3.90), adjusted for age, gender, comorbidities, severity at admission and the Nirmatrelvir treatment within or beyond 5 days of symptom onset (Table 4). The gene discussed is CD8A; the disease is COVID-19.