Big shot names at the annual International AIDS Conference held last week in Vienna, which included philanthropists Bill Gates and Bill Clinton and numerous executive directors of UN health agencies, were treated to a presentation of some exciting new findings: the first ever evidence for biological intervention against HIV-I transmission. The intervention is in the form of a vaginal gel, which contains an anti-HIV drug that reduces the chances of infection by HIV by 39% (a statistically significant reduction). The 2 1/2 year trial consisted of more than 800 women, who were asked to insert the anti-HIV gel, or a placebo, within 12 hours before or after having sex.

This new line of defense against HIV comes at the heels of two other recent major findings of preventative measures against infection. The first is behavioral: school girls and their families receiving small monthly cash payments from researchers had sex later, less often, and with fewer partners. 1 1/2 years after initiation of the payments, girls were less than half as likely to be infected with AIDS. It seems the payments, small as they were, were enough to alleviate the need for girls to have sex in exchange for cash or presents. The second preventative measure found a few years ago was physiological: circumcised men were half as likely to contract HIV. What made that story particularly successful was that many men flocked to hospitals for the procedure because of another motivation: they heard that it made sex better.

The vaginal gel results are exciting because it is the first to unambiguously lay out a medical plan of action for HIV prevention. Prior to this, more than 30 studies of microbicides, vaccines, and drugs had failed, or provided only marginal success. So this is a big step!