The PrEP SMART study is testing a stepped model of scalable adherence support strategies in South African young women who initiate PrEP using a SMART (sequential multiple assignment randomized trial) design.

Women enrolled in the study will be randomized to standard of care adherence support (brief counseling) and either WhatsApp groups or weekly two-way SMS messages. Two months after PrEP initiation, tenofovir drug levels will be measured to determine if participants have achieved high adherence based on their initial randomization. Women with high adherence (i.e., TFV-DP >/=500 fmol/punch from dried blood spots [DBS]) will continue with the adherence support to which they were initially randomized. Participants with low adherence (i.e., TFV-DP <500 fmol/punch from DBS) will continue initial randomization (WhatsApp or two-way SMS) plus be randomized to more one of two more intensive adherence support interventions - continued monthly visits with adherence and problem-focused counseling at months 3-8 or quarterly visits between months 3-9 with feedback about adherence based on drug levels at months 3 and 6.

Inclusion Criteria:

• Female at birth
• Age 18-25 years
• Per participant report, sexually active, defined as having vaginal or anal intercourse at least once in the month prior to screening
• Literate in one or more of the study languages
• Willing and able to provide informed consent
• Able and willing to provide adequate locator information
• Regular access to a mobile phone with SMS and WhatsApp capacity
• Agrees not to participate in other research studies involving drugs or medical devices for the duration of study participation

Exclusion Criteria:

• Planning to relocate in the next 12 months
• Has a job or other obligations that would require long absences from the area (> 4 weeks at a time) for 12 months
• A reactive or positive HIV test at Enrollment
• Any reported PrEP use within the last 6 months
• Concomitant participation in a clinical trial using investigational agents, including placebo-controlled clinical trials using such agents
• Prior participation in the active arm, or current participation in any arm, of an HIV vaccine trial
• Positive pregnancy test

Data from the PrEP SMART Study will be available at the end of the project by contacting the Principal Investigators.

9 months of follow up

Future work is needed to assess optimal approaches for implementing WhatsApp adherence clubs as an alternative support group model. Although the two-way SMS and WhatsApp support groups involved less participant burden and clinic-based procedures than the counseling interventions, they were still time-intensive for staff monitoring the messages. Future PrEP implementation programs considering these approaches will need to decide what level of messaging and phone-based follow-up is feasible.