Sexual risk factors associated with volunteering for HIV vaccine research in South Africa

There are few data on how the risk profiles of individuals who volunteer for HIV vaccine research compare to the general population from which participants are recruited. This study contrasts demographic and sexual risk behaviours among volunteers in an HIV vaccine preparedness cohort with data from a cross-sectional community survey conducted in the same peri-urban community during the same time period. For the HIV vaccine preparedness cohort, structured questionnaires were administered to 140 HIV-negative individuals aged between 16 and 40 years. A questionnaire with identical measures was self-administered in a cross-sectional community survey of 583 randomly selected individuals within the same age range. Compared to the local community sample, individuals who volunteered for the HIV vaccine preparedness cohort were younger (adjusted odds ratio = 0.48; 95% CI = 0.28-0.82), more likely to have had a sexually transmitted disease (adjusted odds ratio = 1.75; 95% CI = 1.03-2.99) and less likely to use condoms (adjusted odds ratio = 0.51; 95% CI = 0.3-0.86). Cohort participants were also more likely to perceive themselves and their partners to be at risk of HIV infection, though these associations did not persist in multivariate analysis. These findings suggest that volunteers for vaccine-related research may be at greater risk of HIV infection than the general population from which they are recruited.