Patients newly diagnosed with HIV at the time of critical illness were older (mean age 49 [SD 11] versus 43 [SD 9] years; p = 0.001) and more likely to be male (78% versus 57%; p = 0.008) and had lower median CD4 counts (40 [IQR 10–78] versus 175 [IQR 53–338]; p < 0.001) and higher median PVL (395000 [IQR 110000–750000] versus 8200 [IQR 0–130000], p < 0.001) compared with those known to have HIV infection at ICU admission. This evidence concerns the gene CD4 and HIV infectious disease.