Aug. 5 (Bloomberg) -- Combining AIDS prevention techniques including condoms, circumcision and possibly drugs now used for treatment might prevent half of the 7 million to 16 million new infections projected over the next seven years, scientists said.

Preventing risky behavior and the spread of the virus also could save $24 billion in treatment costs by 2015, said Michael Merson, a Duke University Global Health Institute researcher, who led one of six studies published in a special issue of the Lancet journal.

No effective HIV vaccine is available in the near future, and preventive gels called microbicides aimed at protecting women from infection have given disappointing results in recent studies, the researchers said. Experimental approaches, such as using antiviral drugs to prevent infections, may change the strategy to stop the disease, said Thomas Coates, a University of California, Los Angeles AIDS researcher, who wrote one of the studies.

``We may have to think about how to spend HIV prevention dollars if these trials are as effective as we all think they should be,'' he said today in a press conference in Mexico City. About 25,000 researchers, advocates, and policy makers are meeting in Mexico at the biennial International AIDS Conference, where the journal was released.

Even as increased access to drug treatment helped reduce AIDS deaths about 10 percent to 2 million in 2007, about 2.7 million people were infected that year, according to UNAIDS, the office that coordinates the United Nations' response to the disease. About 33 million people are infected with the disease worldwide, the agency said.

Circumcision Efforts

Health officials in Rwanda, Kenya and other African countries are using money from the U.S. government and the Seattle-based Bill & Melinda Gates Foundation to increase rates of circumcision in young men. The surgery can reduce the risk a man will catch HIV through having sex with an infected woman by about 60 percent, studies have shown.

``If the 1990s was about combination therapy, this decade is about combination prevention,'' said Mitchell Warren, executive director of the AIDS Vaccine Advocacy Coalition, a New York-based prevention group. ``It's about adding additional options for people. We need more options from which people can choose.''

While condoms provide effective prevention and their use is increasing, they aren't always available and some people don't want to use them, said Warren, who didn't contribute to the Lancet's articles.

``We need a basket of options that are as comprehensive as the epidemic is complex,'' he said.

More sexually active young people need to be educated to reduce risky behaviors, such as unprotected sex, Coates said in the Lancet. Changing norms in some societies and reducing poverty, which has been linked to HIV infections, also would increase prevention, the authors said.

To contact the reporter on this story: John Lauerman in Boston at jlauerman@bloomberg.net.

Last Updated: August 5, 2008 20:29 EDT