The world’s most brilliant anti-AIDS vaccine applicant has proved insufficient. In place of defending volunteers from the fatal virus, the vaccine in fact finished up infecting numerous participants in its extensive clinical experiment on human beings.

The vaccine also failed to lessen the HIV quantity in the blood of those who got the infection, which was the second key objective of the study.

US pharmaceutical giant Merck has now stopped the V520 vaccine test known as STEP. The decision came as a major blow to worldwide expectations of building up a HIV vaccine, which could cut out the spread of this fatal disease.

Earlier tests of the vaccine on animals and slighter tests on humans had revealed hopeful results. This led Merck to start large scale human trials in US, Australia, Latin America and the Caribbean in 2004.

More than 3,000 high risk uninfected volunteers between 18 and 45 years were recruited and three dosages of the vaccine were interjected over six months. The concluding consequence of the vaccine's effectiveness was anticipated by the end of 2008. But early examination of 1,500 volunteers by the independent Data Safety Monitoring Board, handling the test, reasoned out that the vaccine was failing terribly.

In 13 months, 24 cases of infection were reported out of the 741 people who got at least one dosage of the vaccine. That compared with 21 infections out of 762 people who received injections of a dummy vaccine. The research to discover an anti-AIDS vaccine has involved more than 20 clinical trials with tests for more than 30 vaccine candidates still under way.

Merck Research Lab’s president Peter Kim said, “We share in the disappointment of the research and HIV communities today.”