Vaccine News Worse Than Thought

More disappointing news about Merck's recently halted HIV vaccine study.

The vaccine is made from a common cold virus with three synthetic HIV genes tucked inside. It's designed to stimulate the immune system to kill any HIV-infected cells encountered in the future.

However, the researchers found that volunteers with pre-existing immunity to this particular cold virus were much more likely to get infected with HIV if they got the AIDS vaccine than if they got the dummy shot. Some 3,000 people, mostly homosexual men and female sex workers, had volunteered to get the experimental vaccine or dummy shots. All were warned to protect themselves from AIDS exposure.

At the time the study was halted in September, Merck said said 24 of 741 volunteers who got the vaccine in one segment of testing later developed HIV; 21 of 762 participants who got dummy shots also were infected. New data released Wednesday showed that to date, 49 of 914 vaccinated men became infected with HIV, compared with 33 of the 922 men who got dummy shots. Only one woman and a small number of heterosexual men were infected.

Obviously, getting volunteers for future vaccine studies could be much more difficult.