The multi-centered trial, conducted in the United States and the Netherlands and completed in 2003, is described in two papers by the rgp120 HIV Vaccine Study Group, and Peter B. Gilbert and colleagues, which address the vaccine efficacy results and the immunologic responses of the study participants.
The vaccine, produced by VaxGen, was a recombinant construct of the HIV envelope glycoprotein, similar to the type of vaccine used to develop a vaccine for hepatitis B. The vaccine was tested in a double-blind, randomized study of healthy participants who did not use intravenous drugs. The volunteers were men who have sex with men or women at high risk for heterosexual transmission. The vaccine and placebo were given by injection seven times over 30 months and the participants were assessed for risk. At each visit the participants were tested for HIV infection, and for those who were positive, HIV-1 plasma RNA load and CD4 cell counts were monitored on a regular basis for 24 months after the initial diagnosis.
Of the 5,417 volunteers who were enrolled, 368 became infected during the study. The vaccine was found not to be effective in preventing HIV infection; infection rates among those who were given the vaccine and those who were given placebo were 6.7 percent and 7.0 percent, respectively. Of those who became infected during the study, pre-treatment viral loads were similar in the placebo and vaccine groups over their follow-up visits.
During analysis of various subgroups of the study population, a higher, though statistically insignificant, vaccine efficacy was found in th
Contact: Steve Baragona
Infectious Diseases Society of America