Feasibility and suitability of targeting young gay men for HIV vaccine efficacy trials.

We evaluated factors affecting the feasibility of including young high-risk HIV-negative gay and bisexual men in preventive HIV vaccine trials using data from the U.S. Centers for Disease Control and Prevention Collaborative HIV Seroincidence Study. Of 2189 men enrolled in this study, 17% were <25 years of age. HIV seroincidence was 4.2/100 person-years (95% confidence interval [CI], 2.6-7.0) in young men compared with 2.0/100 person-years (95% CI, 1.4-2.6) for older men. Compared with men 25 and older, young men were more likely to report several high-risk behaviors, to perceive themselves to be at risk for HIV infection, and to report that their risk behavior might be increased by participation in an HIV vaccine trial. The majority of both young men (69%) and older men (74%) expressed willingness in participate in HIV vaccine trials. Young men were less likely to answer questions about vaccine concepts correctly and were more likely to be lost to follow-up. Young gay and bisexual men are important candidates for future HIV vaccine trials, but they may need targeted approaches to recruitment, retention, education about trial concepts prior to enrollment, and behavioral interventions during the trial.