CD4 and HIV infectious disease: In univariate analysis, factors significantly associated with insufficient vaccine response (anti-S < 840 AU/mL) included HIV infection with an absolute CD4 count < 200 cells/mcL (6% vs 0%), active malignancy (12% vs 3%), prior nonresponse to hepatitis B (HBV) vaccination (38% vs 18%), and darbepoietin dose > 60 μg/week (29% vs 10%) (Table 3).