Feasibility of chemoprophylaxis studies in high risk HIV-seronegative populations

Administration of antiretroviral medications-recommended to prevent HIV inf ection after occupational exposure-has not been evaluated for safety or eff icacy following nonoccupational exposure. HIV-seronegative persons at incre ased risk for HIV exposure completed a self-administered questionnaire asse ssing their willingness to join studies of this approach. Of 4,572 responde nts, 60% were willing to join a study of a "morning-after" pill; dosing thr ee times a day and mild side effects reduced willingness to 30%. Men who ha ve sex with men (MSM) who reported unprotected anal intercourse in the prio r 6 months were significantly more likely to be willing to join a morning-a fter study than MSM who did not (p = 0.006). MSM favored a preventive HIV v accine over oral chemoprophylaxis; other populations preferred oral chemopr ophylaxis. Interest in studies declined as the hypothetical regimen became more demanding. Studies must emphasize the unknown efficacy of this approac h, given increased interest among MSM at greater risk of exposure.