Promising AIDS Vaccine Stopped

TRENTON, NJ -- Merck & Co said Friday that it has stopped the development of a promising experimental AIDS vaccine after it failed a large international test and that the company has ended enrollment and vaccination of volunteers in the study, which was partly funded by the National Institutes of Health.

Officials at the company said 24 of 741 volunteers who got the vaccine later became infected with HIV, compared to 21 of 762 participants in a comparison group who only received a dummy shots.

"It's very disappointing news," said Keith Gottesdiener, head of Merck's clinical infectious disease and vaccine research group. "A major effort to develop a vaccine for HIV really did not deliver on the promise."

Michael Zwick, an HIV researcher at Scripps Research Institute, said it's too soon to know if other vaccines using the same strategy would also fail, AP reports.

"It's par for the course in the HIV field," he said of the Merck result.

The volunteers in the experiment were mostly from high risk groups for contracting the virus, mainly homosexual men and female sex workers, but none of the participants had HIV at the beginning of the test. According to Merck & Co, they were all repeatedly counseled on how to reduce their risk of HIV infections, including use of condoms.

The National Institutes of Health said in a statement that the vaccine neither prevented HIV infection, nor did it limit severity of the disease in those who become infected with HIV as a result of their own behaviors that exposed them to the virus.