But it's the first real success after a frustrating string of failures with other products that promised to give women the means to protect themselves against getting HIV from a male sex partner.
"The study, while not conclusive, provides a glimmer of hope to millions of women at risk for HIV, especially young women in Africa," study leader Salim S. Abdool Karim, PhD, MBChB, director of South Africa's AIDS research center, says in a news release.
Karim and colleagues enrolled more than 3,000 sexually active women from the U.S., Malawi, South Africa, Zambia, and Zimbabwe. Some of the women used the PRO 2000 product, which blocks the cellular doorway HIV uses to enter cells.
Other women used the BufferGel product, which was not effective. The two active gels were compared to no gel or to a placebo gel.
Importantly, there were no significant safety issues with the gel. There were 36 HIV infections among women using PRO 2000 -- fewer than the 54 HIV infections among BufferGel users, the 51 HIV infections among placebo users, and 53 HIV infections among women using no gel.
Although condom use was high, women who used the gel reported less condom use by their partners. That's troubling. It's a signal that overconfidence in protective gels might reduce use of a much more reliable means of preventing HIV transmission.
The NIH-sponsored trial did not prove PRO 2000 effective. That will be up to a larger, U.K.-sponsored trial involving nearly 9,400 women in Africa. That study should be finished by the end of the summer.
Karim reported the findings at this week's annual Conference on Retroviruses and Opportunistic Infections in Montreal.