Prevalence and Incidence of HIV Among Out-of-Treatment Injecting Drug Users, Chicago 1994–1996

Evaluation of HIV vaccines requires high-risk individuals willing to participate in a vaccine trial. We investigated the willingness to participate in HIV vaccine trials of initially HIV-seronegative homosexual men enrolled in an HIV seroincidence cohort study. Of 815 initially HIV-seronegative participants, 569 (69.8%) reported willingness to participate in an HIV vaccine trial. Altruism was the primary reason given for wanting to participate. Fear of HIV infection from the study's immunizations and a vaccine-induced positive HIV test result were the main reasons for not wanting to participate. Of the 34 study subjects who eventually had HIV seroconversion, 29 (85%) had indicated a willingness to participate. In a univariate analysis, factors associated with willingness to participate included HIV seroconversion during followup (odds ratio OR. 2.6; p = .04), low educational level (OR, 1.6; p = .005), low family income (p = .02), and exchanging sex for housing, food, or clothing (OR 6.1; p = .005). Students were less likely to be willing to participate in a trial (OR, 0.7; p = .03), as well as those who reported sex at the first encounter (OR, 0.7; p = .05). In a multivariate analysis, low education level, infection with Condyloma, and exchanging sex for housing, food, or clothing were positively associated with willingness to participate, whereas being a student and reporting sex at first encounter were negatively associated. In general, factors indicative of high-risk of HIV infection were associated with a higher willingness. These data demonstrate that this high-risk homosexual male cohort has a high willingness to participate in HIV vaccine trials.