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 subj ects was measured. HIV-1-positive individuals (n = 72) were divided into th ree groups on the basis of their CD4+ lymphocyte counts, while the 337 HIV- 1-negative participants were allocated into group four. Haemagglutination i nhibiting (HI) responses varied from 45.8 to 70% in the HIV-1-positive subj ects and were significantly higher in group four (80.7% responses to the H1 N1 strain, 81.6% to the H3N2 strain, and 83% to the B strain). The percenta ge of subjects with HI protective antibody titres (greater than or equal to 1:40) increased significantly after vaccination, especially in HIV-1 uninfe cted subjects. Immunization caused no significant changes in CD4+ counts an d in neither plasma HIV-1 RNA nor proviral DNA levels. Therefore, vaccinati on against influenza may benefit persons infected by HIV-1. (C) 2001 Wiley- Liss, Inc.