First HIV Vaccine That Helps Prevent Infection Is Announced
In Bangkok earlier today, U.S. Army researchers announced the outcome of their recent Phase 3 HIV vaccine trial, the largest yet in history. The results of the trial, known as RV144, were promising – infection was reduced by 31.2 percent among more than 16,000 Thai volunteers.
Although the vaccine does not guarantee complete immunity, “these new findings represent an important step forward in HIV vaccine research,” said Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases in a press release.
A vaccine that is only slightly helpful could still have a big impact. According to UNAIDS, the Joint United Nations Program on HIV/AIDS, 7,500 people become HIV-positive every day.
Since the new vaccine combines two previously tested vaccines that proved to be ineffective, many scientists were skeptical when RV144 began in October of 2003.
“The Thai study demonstrates why the HIV vaccine field must take a balanced approach to conducting both the basic research needed to discover and design new HIV vaccines and, when appropriate, testing candidate vaccines in people,” said Dr. Margaret I. Johnston, director of NIAID’s Vaccine Research Program in the Division of AIDS.
The surprising results of RV144 have “instilled new hope” in the field of HIV vaccine research, according to the World Health Organization and UNAIDS.
The new vaccine works in a “prime-boost” method. The first vaccine, ALVAC, uses a virus from a bird to transport three HIV genes into the human body to prime the immune system. The second, AIDSVAX, contains an artificially created version of an HIV surface protein that boosts the immune response. ALVAC is made by Sanofi Pasteur, a division of Sanofi-Aventis, and AIDSVAX was originally developed by VaxGen Inc.
There are drawbacks to the new vaccine, however. Researchers say it is likely that many years will pass before the vaccine is available to the public. The study also used HIV strains common in Thailand and may not work against HIV strains found throughout the rest of the world.
Another goal of the study was to examine the effect of the vaccine on preventing infected participants from developing full-blown AIDS. Surprisingly, researchers found that the vaccine had no effect on levels of HIV in the blood for those who did become infected during the course of the trial.
This result suggests that scientists need to reevaluate their criteria for assessing the effectiveness of any given HIV vaccine. “Additional research is needed to better understand how this vaccine regimen reduced the risk of HIV infection,” said Dr. Fauci, “but certainly this is an encouraging advance for the HIV vaccine field.”
Details of the $105 million study will be given at the annual AIDS vaccine conference, held this year in Paris from October 19-22.
For more information, please read the news article on the UNAIDS Web site and the press release from NIAID.
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