The humoral response (haemagglutination inhibiting antibodies) to trivalent split influenza vaccine for the 1993-94 winter season (A/Beijing/32/92(H3N2), A/Singaporel 6/86(H1N1) and B/Panama/45/90) was evaluated in a group of young HIV-seropositive ex-intravenous heroin users and compared with responses measured in HIV-seronegative individuals with a similar history. HIV-negative volunteers showed an overall positive response suggesting that previous heroin use did not influence their humoral response to influenza vaccine, Comparable results were obtained in HIV-positive subjects with CD4+ lymphocyte counts >500 mu l(-1), whereas impaired reactivity was found in HIV-positive volunteers with CD4+ counts <500 mu l(-1). Booster vaccination did not increase antibody levels in any of the groups studied, although the data did not exclude a positive influence of a second vaccine dose on persistence of antibody at 120 days after the first dose, No significant changes were observed in p24 antigenemia levels in HIV-positive individuals after vaccination. Copyright (C) 1997 Elsevier Science Ltd.
