- Per participant report, using an effective method of contraception at enrollment, and intending to continue the use of an effective method for the duration of study participation. Effective methods for MTN-028 include: hormonal methods (except contraceptive IVRs), intrauterine device (IUD) inserted at least 28 days prior to enrollment, engages in sex exclusively with women, sterilized (self or partner), and/or sexually abstinent for the past 90 days