Beyond reducing procedural risks, our PJP-specific CRA could enable earlier detection and screening of high-risk groups—such as immunocompromised individuals and/or those on immunosuppressive therapy, pediatric patients or HIV+ individuals with borderline but not yet critically low CD4+ cell counts, or those on immunosuppressive therapy—by identifying those lacking a probably protective T-cell immune response to PJ. This evidence concerns the gene CD4 and pneumocystosis.