Influenza vaccination of HIV-1-positive and hiv-1-negative former intravenous drug users

The immunogenicity of an anti‐influenza vaccine was assessed in 409 former intravenous drug user volunteers and its effect on the levels of HIV‐1 RNA, proviral DNA and on CD4+ lymphocyte counts in a subset HIV‐1‐positive subjects was measured. HIV‐1‐positive individuals (n = 72) were divided into three groups on the basis of their CD4+ lymphocyte counts, while the 337 HIV‐1‐negative participants were allocated into group four. Haemagglutination inhibiting (HI) responses varied from 45.8 to 70% in the HIV‐1‐positive subjects and were significantly higher in group four (80.7% responses to the H1N1 strain, 81.6% to the H3N2 strain, and 83% to the B strain). The percentage of subjects with HI protective antibody titres (≥ 1:40) increased significantly after vaccination, especially in HIV‐1 uninfected subjects. Immunization caused no significant changes in CD4+ counts and in neither plasma HIV‐1 RNA nor proviral DNA levels. Therefore, vaccination against influenza may benefit persons infected by HIV‐1. J. Med. Virol. 65:644–648, 2001. © 2001 Wiley‐Liss, Inc.