Randomized, Double‐Blind, Placebo‐Controlled Efficacy Trial of a Bivalent Recombinant Glycoprotein 120 HIV‐1 Vaccine among Injection Drug Users in Bangkok, Thailand

In Thailand phase 1/2 trials of monovalent subtype B and bivalent subtype B/E (CRF01_AE) recombinant glycoprotein 120 human immunodeficiency virus type 1 (HIV-1) vaccines were successfully conducted from 1995 to 1998 prompting the first HIV-1 vaccine efficacy trial in Asia. This randomized double-blind placebo-controlled efficacy trial of AIDSVAX B/E (VaxGen) which included 36-months of follow-up was conducted among injection drug users (IDUs) in Bangkok Thailand. The primary end point was HIV-1 infection; secondary end points included plasma HIV-1 load CD4 cell count onset of acquired immunodeficiency syndrome-defining conditions and initiation of antiretroviral therapy. A total of 2546 IDUs were enrolled between March 1999 and August 2000; the median age was 26 years and 93.4% were men. The overall HIV-1 incidence was 3.4 infections/100 person-years (95% confidence interval [CI] 3.0-3.9 infections/100 person-years) and the cumulative incidence was 8.4%. There were no differences between the vaccine and placebo arms. HIV-1 subtype E (83 vaccine and 81 placebo recipients) accounted for 77% of infections. Vaccine efficacy was estimated at 0.1% (95% CI -30.8% to 23.8%; P = .99 log-rank test). No statistically significant effects of the vaccine on secondary end points were observed. Despite the successful completion of this efficacy trial the vaccine did not prevent HIV-1 infection or delay HIV-1 disease progression. (authors)