Tinarwo P, et al. - Researchers examined how CD4 count varies at each phase of the HIV disease progression among HIV positive patients due to clinical covariates. Different studies were conducted by the Centre for the AIDS Programme of Research in South Africa in which female patients were initially enrolled in HIV negative cohorts (phase 1). Follow up of seroconverts was done weekly to fortnightly up to 3 months (phase 2: acute infection), monthly visits from 3 to 12 months (phase 3: early infection), quarterly visits thereafter (phase 4: established infection) until antiretroviral therapy initiation (phase 5). They identified 18 out of the 46 CD4 count covariates examined as significant. Compared to entries at higher average CD4 count, faster improvement was noted with low average CD4 counts at acute and early phase entry. During therapy, significantly different patients’ average CD4 counts were induced by all the 18 covariates. During the acute phase, a great variation in the rate of change of CD4 count was noted in response to lactate dehydrogenase. During the early phase, they observed an increase in red blood cells that resulted in the patients’ CD4 counts approaching a common higher level. In response to the red blood cell increase, the already high CD4 counts improved faster than lower ones during therapy. As the monocytes increased, they noted worsening of patients with lower average CD4 counts than those with higher average CD4 counts.