Phase II HIV Vaccine Trials

Preliminary results from the first US National Institutes of Allergy and Infectious Diseases' HIV-1 vaccine trials have suggested that the safety and immunogenicity of the two vaccines tested is acceptable, and that vaccine responses are similar in groups with diverse risk behavior.

296 volunteers, comprising high-risk heterosexuals, men engaging in high-risk sex with men, men having low-risk sex with men, injecting drug users, heterosexual partners of HIV positives and low-risk women/heterosexual men, were enrolled.

The two vaccines tested, Genentech's rgp120 with alum adjuvant and Biocine's rgp120 with MF59 adjuvant, were administered at 0, one, six and 12 or 18 months. The study is still blinded, but a preliminary external analysis has revealed similar antibody and cellular responses among the risk groups. In 88%-96% of individuals the vaccines have elicited neutralizing antibodies, and T-cells specific for HIV can be detected after immunization, suggesting that memory responses are being generated. Five volunteers have acquired HIV-1 infection as a result of high-risk behavior, not as a result of vaccination.