Here's the study page. https://www.purposestudies.com/purpose1/ and extensive details on clinicaltrials.gov https://clinicaltrials.gov/study/NCT04994509 It's double-blind so the patients do not know if they received the drug or an alternative. The investigators inform the patients of the risk and tell them to do what they would usually do. The participants must meet certain criteria including already being sexually active. The investigators would not tell the participants to be more sexually active, or active with more risky people than they normally would. The prevalence of HIV infection in the area is already fairly high so people are actively at risk already. I believe there was only very limited compensation.