This could prove to be a bigger deal than anyone realized over this past summer weekend. Much bigger.

On Saturday in the city of light, scientists announced that their trial AIDS vaccine actually triggered an immune response in humans and also prevented infection in monkeys.

The test results so far are encouraging and perhaps even exciting. But the team warned there are no guarantees it will work during the next experimental phase, testing it on 2,600 women in southern Africa to see if it prevents HIV infection.

“This,” said study leader Dan Barouch of Harvard Medical School, “is only the fifth HIV vaccine concept that will be tested for efficacy in humans in the 35-plus-year history of the global HIV epidemic.”

The World Health Organization estimates 37 million people around the world currently live with HIV/AIDS. About 1.8 million new infections are diagnosed each year with an ensuing million deaths. About 85 million people have been diagnosed since the virus was first identified in the early 1980s. And some 35 million people have already died.

In separate research, the experimental vaccine provided total infection protection to two-thirds of monkeys injected with an HIV-like virus.

Francois Venter of South Africa’s University of the Witwatersrand Reproductive Health and HIV Institute said:

I cannot emphasise how badly we need to have a vaccine…to get rid of HIV in the next generation altogether.

The research team tested the new drug on 393 healthy, HIV-free adults, 18 to 50 years old, in South Africa, Thailand, the United States and east Africa. They received four injections each of seven random samples, including a placebo, over 48 months.

As reported by AFP, the study used so-called ‘mosaic’ vaccine combinations, which combine pieces of different HIV virus types to elicit an immune response. Researchers found the vaccine “induced robust (high levels of) immune responses in humans.”

“Although these data are promising,” Barouch added, “we need to remain cautious.” Hopes were dashed in 2009 when previous research, since abandoned, reduced the risk of HIV infection in a group of 16,000 Thai volunteers by barely 31 percent.

The latest research study results were just published in The Lancet medical journal and come just ahead of the International Aids Conference scheduled for Amsterdam July 23 to 27.