The fact that more than 50 percent of adults with HIV/AIDS in sub-Saharan Africa are women demonstrates the urgent need for female-initiated methods of HIV prevention. But newly published research reports a set-back to efforts to formulate a vaginal gel to prevent transmission of the virus. The candidate gel, formulated with the HIV entry inhibitor cellulose sulfate, was found ineffective at preventing transmission and may have increased the risk of HIV infection.

At three sites in Africa and two in India, lead author Dr. Lut Van Damme and colleagues assessed HIV acquisition in 1,398 high-risk women who were randomized to use either the gel (case subjects) or a placebo (controls) one hour before intercourse for one year.

Interim analysis suggested the gel more than doubled infection risk (hazard ratio: 2.23; p=0.02), though no significant difference between case and control results was noted in the final analysis (hazard ratio: 1.61; p=0.13). The gel had no apparent effect on chlamydia or gonorrhea infection. The evidence of increased risk led the study's monitoring committee to shut down the trial prematurely.

"Despite the disappointing outcome of this study and recently halted vaccine trials, as well as the lack of a protective effect in other recently completed HIV prevention trials, the search for HIV prevention methods that can be initiated by women must continue to help stem the tide of infection in highly vulnerable populations," the authors concluded.

The full report, "Lack of Effectiveness of Cellulose Sulfate Gel for the Prevention of Vaginal HIV Transmission," was published in the New England Journal of Medicine (2008;359(5):463-472).

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