Speaking at the eighteenth International AIDS Conference in Vienna, Austria, this week, Bill & Melinda Gates Foundation co-chair Bill Gates and former U.S. President Bill Clinton urged AIDS activists to get the most out of every dollar given to fight HIV/AIDS, saying donors cannot be expected to give more in these tough economic times unless the money is carefully spent, Reuters reports.

Addressing twenty thousand AIDS scientists, health workers, and activists at the conference, Gates and Clinton said efficiency savings are vital in delivering HIV/AIDS prevention services and treatment in the countries hardest hit and at highest risk. During his speech, Gates outlined several key opportunities for AIDS investments to be more cost-effective and have greater impact, including rapid scale up of cost-effective prevention tools, better use of data to make prevention decisions, reductions in the cost of delivering treatment, and greater investments in vaccines and other breakthrough tools. "We have to be honest with ourselves. We can't keep spending AIDS resources in exactly the same way we do today," said Gates. "As we continue to advocate for more funding, we also need to make sure we're getting the most benefit from each dollar of AIDS funding and every ounce of effort."

Gates presented new modeling projections developed for the Gates Foundation by researchers at Imperial College London that illustrate the dramatic impact smart AIDS investments could have by 2031. For instance, in rural Zimbabwe, where more than 700,000 new infections are projected to occur over the next two decades, scaling up existing prevention tools appropriate for generalized epidemics and introducing an effective vaccine, pre-exposure prophylaxis, and microbicides could cut new infections by up to 90 percent annually.

Although new HIV infections are on the decline, with the number of annual new infections down some 17 percent from 2001 to 2008, the pace of decline is not fast enough to have a significant impact on the course of the epidemic. Indeed, for every two people with HIV who gain access to treatment, another five people become newly infected.

In response to the U.S. government's decision to reduce AIDS funding in the wake of the global recession, hundreds of protestors marched through the conference on its opening day. Addressing the protesters, Clinton said activists need to recognize President Obama as their friend and seek to work with him, not against him. "You have two options here: You can demonstrate and call the president names, or we can go get some more votes in Congress to get some more money," Clinton said. "The world is awash in troubles. It is easy to rail at a government and say...give us more money. But we also have to change the way we do what we do. If we're going to make this case, [donor governments] have to believe that we are doing our job faster, better, and cheaper. Then we have the moral standing to go ask people to give us more money."