AEGiS-15IAC: HIV incidence among AIDSVAX® B/B vaccine trial participants in Montreal, Toronto and Vancouver.

15th International AIDS Conference

Bangkok, Thailand - July 11-16, 2004

HIV incidence among AIDSVAX® B/B vaccine trial participants in Montreal, Toronto and Vancouver.

Int Conf AIDS 2004 Jul 11-16; 15:(abstract no. ThOrC1432)

Lampinen TM, Chan KJ, Logue K, Vincelette J, Hogg RS, Remis RS, Willoughby B, Linnen K, Roy JL, McLean N, Popovic V
BC Centre for Excellence in HIV/AIDS, Vancouver, BC, Canada

OBJECTIVE: To estimate HIV incidence at 36 months among Canadian trial participants in the first phase III HIV preventive vaccine efficacy trial.

METHODS: A randomized, double-blind, placebo-controlled 3-year study to evaluate efficacy of the bivalent rgp120/HIV-1 vaccine (AIDSVAX® B/B) to prevent sexually transmitted HIV-1 infection was completed in Canada in Montreal, Toronto and Vancouver as part of a large trial in North America and Europe. Subjects were men who had sex with men and were vaccinated at 0, 1, 6, 12, 18, 24 and 30 months. At each visit, risk reduction counseling was provided and a questionnaire about risk behaviours in the previous 6 months was administered. Intravenous drug users were excluded from enrollment.

RESULTS: 291 HIV-1 uninfected men who had anal sex with a male partner in the previous year were enrolled from July-October 1999 (105 in Vancouver, 99 in Montreal and 87 in Toronto). Most participants were young (median 37 years), caucasian (93%), and well educated (71% with college education or greater). At the end of the trial, there were 19 seroconverters (10 in Vancouver, 3 in Montreal and 6 in Toronto) yielding an incidence of 2.45 cases per 100 person years (%ppy). Vancouver had the highest incidence (3.65%ppy) while Toronto was slightly less (2.86%ppy) and Montreal the lowest (1.03%ppy). In terms of drop-out, Toronto had the most (25%), with less in Vancouver (14%) and Montreal (5%). Conclusion Our results clearly demonstrate elevated and worrisome rates of HIV infection among participants in the study. Although it is difficult to generalize beyond the study participants, HIV incidence appears much lower in Montreal than in Toronto and Vancouver. These findings may reflect underlying differences in recruitment, sexual behaviours and networks, or the differential impact of HIV prevention strategies in these cities. Further work is needed to explore this issue.

Keywords: AEGIS, Acquired Immunodeficiency Syndrome, AIDS Vaccines, HIV Seropositivity, Incidence, HIV Infections, Risk-Taking, Substance Abuse, Intravenous, HIV-1, Sexual Behavior, Clinical Trials, Phase III, Canada, Europe, North America, AIDSVAX, Humans, Male, epidemiology

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ThOrC1432