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DEC. 20, 2007 - An experimental HIV vaccine, meant to protect against the deadly disease which destroys the body's defenses, appears to have done the opposite. Trial subjects given the vaccine appear even more susceptible to contracting HIV/AIDS than those receiving a placebo.

The results were announced at a special open meeting of the HIV Vaccine Trials Network in Seattle, Wash., and reported in the Journal of the American Medical Association.

Human Immunodeficiency Virus (HIV) is a retrovirus that causes Autoimmune Deficiency Syndrome (AIDS). The virus has proven especially difficult to fight because of its unique method of spreading, infecting the very cells that guard the human body from disease.

Disappointing Results

The experimental virus, which was developed by Merck, produced components of the HIV virus within the subjects in an effort to train the body to recognize and fight the virus.

However, researchers announced that 24 cases of HIV infection were found among those volunteers who took the vaccine. Out of those receiving a placebo, only 21 cases of HIV infection were found.

A total of 741 participants were given the vaccine. 762 received the placebo.

Vaccine Does Not Cause HIV

Researchers agree that that the vaccine did not cause the infections. However, Merck acknowledged the possibility that the vaccine may have made those taking it more susceptible to HIV infection.

"The data from this trial are remarkably complex," said Dr. Keith Gottesdiener, vice presiden of vaccine and infectious disease clinical research for Merck Research Laboratories.

"We are analyzing the data to try to determine if the results are due to immune responses induced by the vaccine, differences in study populations, or some other biological phenomenon we don't yet understand, or simply due to chance." One thing that seems certain: A working vaccine against HIV is a long way away.

Researchers are worried that the failed vaccine will scare off potential trial participants from future studies Forbes magazine reports. This would further set back efforts to stop the disease.

Merck has notified study participants as to whether they received the ineffective virus or a placebo.

The study was co-sponsored by Merck & Co., Inc.; the National Institute of Allergy and Infectious Diseases (NIAID), part of the U.S. National Institutes of Health; and the HIV Vaccine Trials Network (HVTN), which is funded by NIAID.

Sources:

Stephenson, Joan. "HIV Vaccine Concerns?" Journal of the American Medical Association. Vol. 298, Number 23, Dec. 19, 2007.

HIV Vaccine Trials Network. www.hvtn.org. Accessed Dec. 19, 2007.

"Fallout from failed vaccine could dampen research." Forbes. www.forbes.com. Published Nov. 12, 2007. Accessed Dec. 19, 2007.

"Data from STEP Study Presented..." Merck press release. Nov. 7, 2007. Accessed Dec. 19, 2007.

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