HIV Vaccine Trial Cancelled

Author: Madeline Ellis

For nearly a quarter of a century, U.S. government health officials have been trying to develop an effective HIV vaccine. In a 1984 news conference, top officials said they were optimistic that they would have a marketable vaccine within three years, but that time has long since come and gone. The latest setback came just days ago when plans for a large-scale trial of a promising vaccine were cancelled in favor of a smaller, more focused study. The decision was made by Dr. Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID), who said that until smaller studies could determine whether the vaccine could significantly lower the amount of HIV in the blood of those who could become infected "a large trial is not justified."

The vaccine, aptly named PAVE—Partnership for AIDS Vaccine Evaluation—after the consortium of federal agencies and federally financed organizations involved in developing and evaluating experimental HIV vaccines, is among a new class of drugs and similar to a Merck vaccine that failed last year. The trial was to have begun enrolling 8,500 volunteers last October, but was postponed after the Merck vaccine not only failed its two main objectives, but was thought to have increased the risk of becoming infected. The coming trial had been planned to include 2,400 male volunteers and would have cost about $63 million.

Dr. Fauci said his decision came after meeting with scientists to try to understand why the Merck vaccine failed. He said not enough is yet known about which immune reactions are the most important in preventing the infection and that more studies of the interaction between the immune system and HIV are needed in order to design effective prevention. He said it would be better to go "one step at a time," doing smaller, more focused testing and following that lead should one get results. "Show me that the vaccine works by lowering the amount of HIV in the blood, and then we will move to a larger trial that will document the link with a particular immune response."

Dr. Alan Bernstein, executive director of the Global HIV Vaccine Enterprise, said that his organization supports Dr. Fauci's decision, according to The New York Times. Dr. Bernstein said there is an "urgent need for a diversity of new approaches to HIV vaccine design." He notes that recent laboratory advances that allow scientists to look at hundreds of genes simultaneously "offer immense promise in helping us understand how to design new HIV vaccine candidates that can achieve long-lasting immune protection."

About 33 million people in the world are infected with the AIDS virus, and 2.5 million new infections occur each year. Since it was first identified in the 1980s, AIDS has killed 25 million people. The NIAID says "an HIV vaccine continues to be our best hope for ending the HIV pandemic" but while approximately 30 vaccines are currently being tested, none have even come close to preventing the infection.