A U.S. biotechnology company says it could have a vaccine to prevent AIDS in less than three years if tests around the world show it works and is safe. Officials of the California firm VaxGen say they believe that tests will show their vaccine to be effective in preventing transmission of the AIDS virus HIV.
Thousands of volunteers at high risk for the virus are being inoculated with the vaccine in two separate trials worldwide to see if it keeps them from acquiring the disease. One is testing the vaccine in 5,400 heterosexual and homosexual men and women in North America and Europe. The other is experimenting with a group of 2,500 injection drug users in Thailand.
An AIDS vaccine is considered the best hope for curtailing the pandemic, even if it does not work in everyone who receives it because blocking some transmission would prevent many new cases.
If the VaxGen vaccine shows significant efficacy, company president Donald Francis says his firm will be ready to begin production of the drug by early 2005. "The computer models show that if you have a 30 percent effective vaccine, you ultimately can drive the epidemic into the ground generation after generation," he explained. "Our desire obviously is to have a 100 percent effective vaccine."
Mr. Francis says the VaxGen vaccine worked well in chimpanzees and in small, preliminary human studies of safety and efficacy. He expects the results from the current, much bigger human experiments to be available early next year.
The vaccine works like every other vaccine. It introduces parts of the disease molecules into the body to stimulate the immune system to produce antibodies. The antibodies thus enlisted into service then are available to block the complete disease organism from attaching to healthy cells. VaxGen says its vaccine is safe because only a molecule on the surface of the virus is used in it to attract antibodies, not the deadly parts of the virus.
"Antibodies protect against viral infection," Mr. Francis continued. "That's what vaccines are based on. That has been the foundation. I'm talking about preventing infection in the first place. If you have the right antibodies, you will not get infected with HIV or any other viral disease. The question is, can you make those right antibodies? That's our hope with the vaccine."
The experimental vaccine comes in two formulations: one for the HIV subtype found in North America and Europe, the other for one that infects Thailand. Should the test results be strong, the company plans to market the various formulations with production help from a South Korean vaccine manufacturer. The challenge will be to develop a version for Africa, which has several subtypes of the AIDS virus.
Dozens of AIDS vaccines are in various stages of development and testing, but the VaxGen product is the furthest along. Thai and U.S. health officials announced at the Barcelona conference Monday they are awaiting approval of their governments to begin testing it in combination with a second experimental vaccine later this year in Thailand.
The second compound is made by the Swiss company Aventis Pasteur. Rather than stimulating antibodies, it evokes a response from warrior white blood cells. It would be used for the initial inoculation with a later boost from the VaxGen product.
The tests are designed to determine if this dual approach is better than using just antibodies alone.