Indeed, vitamin D deficiency has been associated with clinical and pre-clinical endpoints in HIV-infected persons: all-cause mortality during untreated [17] and treated [18], [19] HIV infection, lesser CD4 cell gain on antiretroviral therapy [20], [21], AIDS and non-AIDS-defining events [18], [22], [23], insulin resistance [24], type 2 diabetes [25], and atherosclerosis [26]–[28]. Here, CD4 is linked to HIV infectious disease.