The randomization scheme will be stratified by site and will be generated and maintained by the MTN SDMC. The SDMC will provide two sets of sealed, opaque randomization envelopes to each study site. The two sets are linked by sequential envelope number. One set of envelopes is stored and used in the study clinic. The other set is stored and used in the study pharmacy. The clinic envelopes will contain an assignment to vaginal or oral product. Clinic staff will assign these envelopes in sequential order by envelope number to eligible study participants. Assignment of the clinic randomization envelope is considered the effective act of participant enrollment/randomization. Clinic staff will prepare a written prescription that, among other things, documents the randomization envelope number to which the participant was assigned and the assignment to vaginal or oral product. Prescriptions for these participants will be delivered to pharmacy staff members who will dispense study product according to the information contained in the corresponding pharmacy randomization envelope. The pharmacy envelopes contain coded (blinded) information indicating the specific oral or vaginal product to which participants are assigned.