HIV Vaccine Regimen Shows Modest Benefits

Study finds trend toward prevention of infection in population with mostly heterosexual risk

TUESDAY, Oct. 20 (HealthDay News) -- A vaccine combination may decrease the risk of HIV infection in a community-based population that has a largely heterosexual risk, according to a study published online Oct. 20 in the New England Journal of Medicine to coincide with the AIDS Vaccine Conference, held from Oct. 19 to 22 in Paris.

Supachai Rerks-Ngarm, M.D., of the Ministry of Public Health in Bangkok, Thailand, and colleagues performed a randomized, community-based, double-blind, placebo-based trial, in which they injected 16,402 healthy men and women with four priming injections of the recombinant canarypox vector vaccine ALVAC-HIV and two booster injections of the recombinant glycoprotein 120 subunit vaccine AIDSVAX B/E. The subjects were between 18 and 30 years of age and primarily at heterosexual risk for HIV infection.

In an intention-to-treat analysis involving all vaccine recipients, the researchers found that the vaccine efficacy was 26.4 percent. In a per-protocol analysis that involved 12,452 vaccine recipients, the vaccine efficacy was 26.2 percent, and there was a vaccine efficacy of 31.2 percent in a modified intention-to-treat analysis involving all 16,402 recipients, except seven who were found to have had HIV-1 infection at baseline. In subjects later diagnosed with HIV-1, vaccination didn't affect degree of viremia or CD4+ T-cell count.

"Although our study provided preliminary evidence that an HIV vaccine regimen has the potential to prevent infection, it did not have the power to address two intriguing considerations: vaccine efficacy may have decreased over the first year after vaccination, and vaccine efficacy may have been greater in persons at lower risk for infection," the authors conclude.

Sanofi Pasteur provided the ALVAC-HIV vaccine for the study, and three of the researchers reported being employees of the company.

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