WASHINGTON — Call it a triple win for fighting the AIDS epidemic: Treating people with HIV early keeps them healthy, cuts their chances of infecting others, and now research shows it’s also a good financial investment.

The International AIDS Conference closed Friday with the message that getting treatment to more of the world’s 34 million people with HIV is key to curbing the epidemic, short of a vaccine and cure that are still years away.

‘‘It is unacceptable’’ that scientifically proven treatment and prevention tools are not reaching people who need them most, Dr. Francoise Barre-Sinoussi, a Nobel laureate, co-discoverer of the AIDS virus, and new president of the International AIDS Society, told the meeting’s closing session.

Former president Bill Clinton, whose foundation funds HIV work, also addressed the group.

‘‘All of you have created the possibility that we could have an AIDS-free generation,’’ he said. ‘‘We just have to keep pushing the rocks up the hill.’’

Spreading treatment will be hugely expensive up-front, but Harvard researchers said Friday that the investment would actually save hard-hit South Africa money over five years, as savings from treating AIDS-related illnesses exceed the medications’ price.