CD4 and COVID-19: Three factors were found to be independently associated with progression to severe COVID-19 (Table 5) during 14 days of hospitalization after admission, and these factors are as follows: (a) age 65 years or older (HR = 8.456; 95% CI: 2.706–26.426; p < 0.001); (b) creatine kinase (CK) ≥ 180 U/L (HR = 3.667; 95% CI: 1.253–10.733; p = 0.018); and (c) CD4+ T-cell counts <300 cells/μL (HR = 4.695; 95% CI: 1.483–14.856; p = 0.009).