However, studies to assess the safety of early discontinuation of prophylaxis for pneumocystosis before the CD4 counts increase to ≧200 cells/μL have not been performed until recently when D'Egidio and colleagues followed 19 HIV-infected patients with sustained HIV RNA levels < 50 copies/ml and a median of CD4 count of 120 cells/μL who discontinued secondary prophylaxis without relapse after an observation duration of 13.7 months [11]. This evidence concerns the gene CD4 and pneumocystosis.