Merck Halts HIV Vaccine Trial: Vaccine is "Ineffective"

By Anastacia Mott Austin

People hoping for a breakthrough in HIV vaccination studies were disappointed this week to hear that Merck is suspending its HIV vaccination trials because the vaccine appears to "be ineffective."

The international study, begun in December of 2004, was co-sponsored by the pharmaceutical company Merck & Co. and the HIV Vaccine Trials Network and funded in part by the National Institutes of Health. Called STEP, the program involved 3000 international volunteers who were HIV-free at the beginning of the study, but considered at high risk for contracting the disease. Most participants were either female sex workers or homosexual men.

Merck was careful to point out that during the trial, the volunteers were heavily counseled about safe sex practices such as using condoms to avoid HIV infection.

In one part of the study, two groups of approximately 700 subjects each were studied separately. In the group receiving the HIV vaccine, 24 out of 741 volunteers became infected with the HIV virus, while 21 out of 762 became infected of the control group not receiving the vaccine.

The vaccine study involved a new method of trying to stop the HIV virus, by using a weakened version of the common cold virus with added proteins of HIV genes, in hopes that the proteins would "warn" the body’s infection-fighting cells to recognize and destroy the HIV virus.

Keith Gottesdiener, the leader of Merck’s vaccine research group, told reporters, "The concept was that if someone getting the vaccine is later exposed to HIV, the immune system would recognize those HIV proteins and go after the virus."

Unfortunately, the current incarnation of the technology failed to protect against HIV.

Added Gottesdiener, "It's very disappointing news. A major effort to develop a vaccine for HIV really did not deliver on the promise."

It is estimated that over 1 million Americans are currently infected with the HIV virus, and HIV continues to be a significant concern in developing countries where access to expensive anti-viral drugs is limited.

Mark Feinberg, Merck’s vice president of medical affairs in the vaccine department, said to the press, "No one really knows when and if we will ever have an effective HIV vaccine because the virus is such a great challenge."