Willingness of injection drug users to participate in an HIV vaccine efficacy trial in Bangkok, Thailand.

We assessed willingness to participate in an HIV recombinant gp120 bivalent subtypes B/E candidate vaccine efficacy trial among 193 injection drug users (IDUs) attending drug treatment clinics in Bangkok, Thailand. IDUs previously enrolled in a prospective cohort study were invited to group sessions describing a potential trial, then completed questionnaires assessing comprehension and willingness to participate. A week later, they completed a follow-up questionnaire that again assessed comprehension and willingness to participate, as well as barriers to and positive motives for participation, with whom (if anyone) they talked about the information, and whether others thought participation was a good, bad, or neutral idea. At baseline, 51% were definitely willing to participate, and at follow-up 54%; only 3% were not willing to participate at either time. Comprehension was high at baseline and improved at follow-up. Participants who viewed altruism, regular HIV tests, and family support for participation as important were more willing to volunteer. Frequency of incarceration and concerns about the length of the trial, possible vaccine-induced accelerated disease progression, and lack of family support were negatively associated with willingness. Overall, IDUs comprehended the information needed to make a fully informed decision about participating in an rgp120 vaccine efficacy trial and expressed a high level of willingness to participate in such a trial.

"Why I am not infected with HIV": implications for long-term HIV risk reduction and HIV vaccine trials.

OBJECTIVE: To describe beliefs about remaining HIV-seronegative in injecting drug users in two high-seroprevalence cities, and to consider implications of these beliefs for ongoing risk reduction efforts and for HIV vaccine efficacy trials. DESIGN: Cross-sectional survey with open- and closed-ended questions. SUBJECTS: 58 HIV-seronegative injecting drug users participating in HIV vaccine preparation cohort studies in New York City, New York, U.S.A., and Bangkok, Thailand. MAJOR FINDINGS: Large majorities of subjects in Bangkok (90%) and in New York (89%) believed their "own efforts" to practice safer injection methods and safer sex were very important in avoiding HIV infection. More Bangkok subjects (30%) believed that they would "probably" become infected with HIV in the future than New York subjects (4%). Three percent of Bangkok subjects and 70% of New York subjects believed "having an immune system strong enough to avoid becoming infected with HIV despite exposure to the virus" was very important in avoiding HIV infection. This belief in New York subjects was associated with having previously engaged in high-risk behaviors (i.e., sharing injection equipment, unprotected sex, or both) with partners known to be HIV-seropositive. CONCLUSIONS: Risk reduction programming for high-HIV-seroprevalence populations and within HIV vaccine trials should address not only specific HIV risk behaviors, but also the complex belief systems about avoiding HIV infection that develop within such groups. The person's "own efforts/self-efficacy" appears to be central in the psychology of risk reduction. Members of some high-risk populations may overestimate greatly the frequency of any possible natural immunity to becoming infected with HIV. Prevention programs for these populations will need to address explicitly the probabilistic nature of HIV transmission.

PIP: Both New York City and Bangkok have experienced rapid, large-scale HIV epidemics among their IV drug using populations. The authors surveyed 58 HIV-seronegative IV drug users (IVDUs) participating in HIV vaccine preparation cohort studies in the two cities to gain insight into their beliefs about remaining HIV-seronegative. The 28 IVDUs in New York City and 30 IVDUs in Bangkok were recruited from ongoing cohort studies of HIV incidence among IVDUs in these cities. The New York cohort subjects were 76% male, 30% White, 27% Black, 43% Latino, and of median age 42 years. The majority had injected both heroin and cocaine. The Bangkok cohort subjects were 94% male, 100% Thai, of mean age 32 years, and almost all had injected heroin only. 89% of the subjects in New York City and 90% in Bangkok believed that their own efforts to practice safer injection methods and safer sex were very important in avoiding HIV infection. However, 4% of New York subjects and 30% of Bangkok subjects thought that they would probably become infected with HIV in the future. 70% of New York subjects and 3% of Bangkok subjects believed that having an immune system strong enough to avoid becoming infected with HIV despite exposure was very important in avoiding HIV infection. This latter belief among New York subjects was associated with having previously engaged in high-risk behaviors with partners known to be HIV-seropositive. Risk reduction programming for such populations and within HIV vaccine trials must take into account the prevailing belief systems about avoiding HIV infection.