When data were analyzed by HCV co-infection, it was noted that 1.2% (95%CI, 0.002–0.03) of non HCV co-infected patients had CD4+ values below 350 cells/mm3 in the arc of a year, while the percentage increased to 3.2% with reference to HCV co-infected patients (i.e. patients with HCV antibody positive) (95% CI, 0.01–0.08). Here, CD4 is linked to coinfection.