Eligibility criteria
The eligibility criteria for this study encompassed the following: 1) men (cis or transgender) and transgender women between 18–35 years old; 2) HIV-1 or HIV-2 uninfected at Screening and Enrollment; 3) in general good health at Screening and Enrollment (e.g., medical and medication history, physical exam including a rectal exam); 4) a reported history of consensual RAI at least three times in the past three months and expectation to maintain at least that frequency of RAI during study participation; 5) For individuals who could get pregnant (transgender men with a female reproductive system), a negative pregnancy test at Screening and Enrollment; 6) For individuals who could get pregnant, use of an effective method of contraception for at least 30 days (inclusive) prior to Enrollment, and intention to use an effective method for the duration of study participation; 7) ability and willingness to provide written informed consent in local language; 8) ability and willingness to provide adequate locator information; 9) availability to return for all study visits and willingness to comply with study participation requirements;10) willingness to not take part in other research studies involving drugs, medical devices, genital or rectal products, or vaccines for the duration of study participation [