Comparison of the effects of acute influenza infection and Influenza vaccination on HIV viral load and CD4 cell counts.

Abstract

Influenza vaccination is recommended for HIV-infected patients, although the efficacy is not clear. Prior studies have yielded differing results with regard to the effects of influenza vaccination on HIV viral load and CD4 cell counts. The effects of acute influenza on HIV viral replication and CD4 cell counts have not been well described. We sought to assess the effect of influenza infection and vaccination on HIV viral load and CD4 cell counts. All cases of influenza occurring in HIV-infected individuals over 3 years at a large county hospital were reviewed. For the year 1997-1998, data on all HIV clinic patients who were vaccinated for influenza were recorded prospectively. In order to assess the effects of influenza infection (Group I) and vaccination (Group II) on HIV viral load and CD4 cell counts, values from before and after influenza infection or vaccination were compared to each other and to a matched control group not vaccinated and without influenza infection (Group III). Forty-three cases of influenza were diagnosed. Pre- and post-influenza viral load in Group I was not significantly different: 3.34 versus 3.49 log copies/ml (P=0.36). Viral load was unchanged in 22 of 37 patients, increased in ten patients and decreased in five patients. Similarly, pre- and post-vaccination viral load in Group II was not significantly different: 3.52 versus 3.66 log copies/ml (P=0.12). Thirty-four of 47 patients who received influenza vaccine had no significant change in viral load-viral load increased in ten patients and decreased in three patients. No significant CD4 cell count changes were noted following influenza infection or vaccination. In contrast, Group III patients experienced a small decline in viral load from 4.23 to 3.39 log copies/ml, P<0.05, while there was a trend towards an increase in CD4 cell counts (P=0.06). Following influenza infection or vaccination, most patients did not have a significant increase in HIV viral load or decrease in CD4 cell count.