Large-Scale Trial Of Merck's Experimental HIV Vaccine To Begin In South Africa

A large-scale trial of Merck's experimental HIV vaccine, called MRKAd5 HIV-1, is set to begin in South Africa, the Wall Street Journal reports (Wall Street Journal, 2/9). The trial -- announced on Thursday and to be conducted by the South African AIDS Vaccine Initiative and the HIV Vaccine Trials Network -- is supported by the National Institute of Allergy and Infectious Diseases. It will involve 3,000 HIV-negative men and women, making it the largest HIV trial to be conducted in Africa to date. The vaccine cannot infect participants with the virus because it contains copies of three HIV genes and not live HIV (NIAID release, 2/8). The trial aims to test whether the vaccine can either prevent HIV transmission or lower levels of HIV in people who contract the virus. The study also likely will provide new information about how the vaccine might work in a heterosexual population; how it might work in women; and whether it would be effective in populations with pre-existing immunity to the viral vector used in the vaccine, I-Net Bridge/Mail and Guardian reports (I-Net Bridge/Mail and Guardian, 2/8). Researchers also are seeking to determine whether the vaccine, which is based on the B strain of the virus, would be effective against the C strain of HIV -- the prevalent strain in South Africa. During the four-year trial -- which will enroll healthy, sexually active people ages 18 to 35 -- some participants will be given the vaccine and some will be given a placebo version. The trial will not enroll pregnant women (BBC News, 2/8). All participants will receive regular counseling on how to reduce their risk of contracting the virus and will be given condoms. Participants also will be provided with access to care and treatment for sexually transmitted infections. In addition, because of recent studies showing that male circumcision can reduce a man's risk of HIV infection, circumcision will be provided for men who request it (SAAVI release, 2/8). The vaccine already has been tested for safety and immune response in Africa, the Americas and Australia. South Africa's Medicines Control Council and the country's Department of Agriculture have approved the trial, and FDA in the U.S. has reviewed it (BBC News, 2/8). The trial will be run by researchers at the Fred Hutchinson Cancer Research Center and the Perinatal HIV Research Unit at the University of Witwatersrand. If this trial is successful, another likely will be launched in three to five years that would involve 10,000 or more participants, according to James Kublin of the Hutchinson Center (King, Seattle Times, 2/8).

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