Sexual risk behaviour of the first cohort undergoing screening for enrollment into Phase I/II HIV vaccine trials in South Africa.

We assessed risk behaviour in a heterosexual cohort undergoing prescreening for the first Phase I/II HIV vaccine trials in Soweto. We developed a survey and collected self-reported data from HIV-negative potential volunteers. Of 488 participants, most were single and approximately half were from households with incomes below the poverty level. Males reported higher rates of heavy alcohol use (P < 0.001), marijuana use (P < 0.001) and other recreational drug use (P < 0.01). Males reported more sex partners than females in the previous six months (P < 0.001), as well as more casual/anonymous partners (P < 0.001) and one-night stands (P < 0.001). Multivariate analyses revealed substance use and male gender predicted higher risk behaviours, including <100% condom use with known/suspected HIV-positive partners, having casual/anonymous partners and having more than two partners. For this population, male volunteers may need increased risk-reduction counselling during Phase I/II trials and additional recruitment methods may be necessary to identify high-risk female volunteers for Phase III efficacy trials.

Anticipated changes in sexual risk behaviour following vaccination with a low-efficacy HIV vaccine: survey results from a South African township.

We assessed the potential for anticipated changes in sexual risk-taking behaviour following hypothetical administration of a low-efficacy preventive HIV vaccine. We developed a survey and collected self-reported data from 158 HIV-negative volunteers in a cohort undergoing prescreening for Phase I/II HIV vaccine trials in Soweto. Overall, 22% reported they might use condoms less frequently; 9% reported that they might increase their frequency of sex with casual/anonymous partners; and 55% reported their sexual partners might want to use condoms less frequently knowing they were vaccinated. Multivariate analyses revealed that anticipated decrease in condom use was predicted by poor comprehension and by young age. Individuals may increase their risk-taking behaviour knowing that a vaccine would provide only incomplete protection against HIV transmission. In HIV vaccine trials and future vaccination programmes, education and risk-reduction counselling will be needed for vaccinated individuals and their partners, and mass media education campaigns may be necessary.