Among ventilated individuals, the rate of invasive mechanical ventilation (IMV) was relatively lower in patients with CD4+ T lymphocyte counts < 71/μl when compared to those with CD4+ T lymphocyte counts ≥ 71/μl (75% vs. 90%, Figure 1(e)), which may indicate the worry of ventilator-associated pneumonia for patients with severe lymphocytopenia. This evidence concerns the gene CD4 and ventilator-associated pneumonia.