CONSORT disposition of participants.
Participants were recruited from a variety of sources, including outpatient clinics, universities, community-based locations, online websites, and social networking applications. In addition, participants were also referred to the study from other local research projects, research registries and other health and social service providers. At some sites, prospective participants were pre-screened by phone, using an IRB-approved phone script, to assess presumptive eligibility based on select behavioral and medical eligibility requirements. This includes a review of the prospective participants’ sexual history and engagement in receptive anal sex in their lifetime and within the previous three months. For those deemed presumably eligible when a phone screen was conducted, a screening visit was scheduled. A re- affirmation of all eligibility criteria was obtained and confirmed during a formal screening and enrollment visit, described below.The study was reviewed and approved by Institutional Review Boards (IRB)/Ethics Committees at all participating institutions, including the Health Research Ethics Council, South African Health Products Regulatory Authority, the College of Medicine Research and Ethics Committee, the Johns Hopkins Bloomberg School of Public Health IRB, the Research Institute for Health Sciences Human Experimentation Committee, the Medical Device Control Division/Thai Food and Drug Administration (FDA), the IMPACTA Bioethics Committee, the Peruvian National Institute of Health (Instituto Nacional de Salud), the Peruvian FDA, the Peruvian Ministry of Health, the University of Pittsburgh IRB, the University of California San Francisco IRB, University of Alabama at Birmingham IRB, and the University of Pennsylvania IRB. This study was submitted to clincialtrials.gov on September 14, 2018, assigned number NCT03671239.