CD19 and viral pneumonia: As part of this analysis, we confirmed that the duration of oxygen treatment in the form of HFNO (p < 0.001), age over 60 years (p < 0.001), Ne/Ly values of >6 (p < 0.001), selected lymphocyte subtypes—CD4+ < 0.2 × 109/L (p = 0.035), CD8+ < 0.2 × 109/L (p < 0.001), and CD19+ < 0.1 × 109/L (p < 0.001)—as well as selected biochemical inflammatory markers—IL-6 > 50 ng/L (p < 0.001) and lactate > 3 mmol/L (p < 0.001)—are significant risk factors associated with the death of patients from viral pneumonia in hospitals.