Part of the vaccine was developed in the Bay Area by a company called Vaxgen, which is now owned by Global Solutions for Infectious Diseases of South San Francisco.
About 16,000 heterosexuals participated in this study. Half were given the vaccine and the rest a placebo. The study found the vaccine cut the risk of HIV infection by more than 31 percent.
It was a two vaccine combination -- one called Alvac, the other Aidsvax owned by Global Solutions for Infectious Diseases of South San Francisco.
Alone they never worked, but together they seem to.
"So you have a prevention of infection, then if it breaks through, you've got a lowering of viral load," said vaccine developer Lance Ignon.
But the strains in Thailand are different from the ones in the U.S.
"Is it going to work in the United States or Europe. Well, not necessarily but we can take exactly the same procedure and put in proteins from the virus that is most common in this country," said UCSF researcher Dr. Jay Levy.
The U.S. Army led the trials. Their researchers and those from the National Institute of Allergy and Infectious diseases sponsored it.
"Thailand has experience doing this. They conducted the first phase three trial of an HIV vaccine or one of the first two with Vaxgen," said Ignon.
But the Vaxgen trials failed in 2003 and this time there is more promising news. Still, some fear the prevention message will be lost.
"Continue using condoms, if people are using syringes to inject drugs, use clean ones, if you are concerned about HIV get tested," said Mark Cloutier from the San Francisco AIDS Foundation.
Diane Jones has been a nurse at San Francisco General Hospital for 27 years. She was there to treat some of the early patients with HIV and AIDS.
"We have the wealth in the world to do this so really fundamentally a question of political will. If we have the political will to do it, I think the science will be able to deliver and I hope we do," said Jones.
The vaccine cut the rate of HIV by 31 percent, but in order to begin distributing a vaccine worldwide, health authorities would like to see it work in 80 percent of the cases.