Few young women at risk of HIV infection are initiating pre-exposure prophylaxis (PrEP) for HIV prevention in Kenya, thus we propose refining and testing a new model to increase PrEP initiation among young women at high HIV risk that has never been explored: enhanced peer PrEP referral with HIV self-test (HIVST) delivery. We conducted formative research to design of a model that is acceptable to young women and feasible to implement in Kenya. In this study, we will refine this model where young (≥16 to 24 years) female PrEP users refer their peers to PrEP and deliver HIVSTs in a pilot study and then test the refined model in a hybrid effectiveness-implementation trial. We hypothesize that relative to standard informal word-of-month peer PrEP referral (currently ongoing in Kenya), enhanced peer PrEP referral with HIVST delivery will increase PrEP initiation, continuation, and adherence among peers; have high fidelity; and be low cost.

HIV PrEP is highly effective, but uptake remains low among young women in Africa, one of the populations at greatest HIV risk. In Kenya, one of the target groups for HIV incidence reduction is young women (16-24 years), who account for 33% of the total of new HIV infections yet comprise only 10% of the population. Barriers to PrEP initiation for this population are multi-faceted and include institutional (e.g., stigma associated with use) and intra-personal (e.g., lack of PrEP knowledge or self-efficacy) barriers. Thus, innovative PrEP delivery models that can overcome these barriers are needed. The opinion of peers often influences the behaviors and preferences of young women, including those related to health and health care. Most young women who have initiated PrEP in Kenya to date have done so because of informal peer referral, thus peer referral enhanced with training and HIVST delivery has the potential to increase PrEP initiation among members of this population. HIVST is a new technology that has the potential to enhance peer PrEP referral. Much of the emphasis on HIVST to date has been on identifying new individuals living with HIV and facilitating linkage to treatment, but most individuals who self-test will test negative and may be interested in starting prevention services, like PrEP.

We hypothesize that an enhanced peer PrEP referral model with HIVST delivery can increase PrEP initiation among young Kenyan women at HIV risk compared to standard informal peer PrEP referral. We conducted formative qualitative research to inform the design of such a model and propose refining this model in a pilot study with 16 young female PrEP users (i.e., "peer providers" or "index peers") who will be encouraged to referred up to four peer (i.e., "peer clients" or "referred peers"; =64 in total) using the defined implementation strategies (i.e., formalized training on PrEP and HIVST, and HIVST delivery). At one month, we will measure model adoption (e.g., peer referral, PrEP initiation) and feasibility (e.g., peer follow up) using survey data and qualitatively measure model acceptability using focus group discussions (FDGs) with index and referred peers (4-5 FDGs, 3-6 women/FDG).

We will incorporate findings from the pilot into a refined version of the enhanced peer PrEP referral with HIVST delivery model and test this compared to standard peer PrEP referral in hybrid effectiveness-implementation cluster-randomized controlled trial (cRCT). In our cRCT, we will randomize 80 index peers to either: 1) enhanced peer PrEP referral, where they are encouraged to refer 4 peer (i.e., "referred peers") to PrEP using an educational brochure, HIVSTs (2/peer), and a MOH-style referral slip, or 2) standard peer PrEP referral, where they are encouraged to refer 4 peer clients to PrEP using word-of-mouth, as is ongoing in Kenya, and a MOH-style referral slip. All trial outcomes will be measured among referred peers, as reported by index peers, three months later. Effectiveness outcomes will include PrEP initiation [primary], PrEP continuation (any refilling), and recent HIV testing (past 3 months); self-reported PrEP adherence will be assessed among referred peers reached for follow-up. Implementation outcomes will include model acceptability, fidelity, and costs. The results from this cRCT will address one of the greatest challenges to PrEP scale-up today and inform an R01 proposal for a community-randomized trial and budget impact analysis.

Inclusion Criteria:

For peer providers (qualitative data, pilot):

• Age ≥16 to 24 years*
• Female
• Have been on PrEP for a minimum of three months
• Good adherence to PrEP (i.e., self-report take PrEP all the time)
• Willing to disclose PrEP use to their peers
• Able to identify up to 4 peers at risk of HIV infection
• Willing to participate in training with study counselors on PrEP referral and HIVST use
• Willing to refer peers to PrEP and deliver HIVSTs
• Able and willing to provide written informed consent
• Per the discretion of the site investigator, no clear risks of social harm or inability otherwise to reasonably conduct HIVST at home in the context of PrEP delivery

For peer providers (cRCT):

• Age ≥16 to 24 years*
• Female
• Must have refilled or initiated PrEP (i.e., been dispensed PrEP)
• Not currently enrolled in an HIV study
• Able to identify up to 4 peers with recent self-reported behaviors associated with risk of HIV acquisition
• Willing to participate in training with study counselors on PrEP referral and HIVST use
• Willing to refer peers to PrEP and deliver HIVSTs
• Able and willing to provide written informed consent
• Willing to provide contact information for follow-up
• Willing to engage in all research activities including completion of questionnaires
• Per the discretion of the site investigator, no clear risks of social harm or inability otherwise to reasonably conduct HIVST at home in the context of PrEP delivery

For peer clients (pilot, RCT):

• Age ≥16 to 24 years*

• Female

• Referred by peer (i.e., a PrEP users) to initiate PrEP

• Able and willing to provide informed consent

  • NOTE: We will only enroll young women ≥16 to 17 years into the study if they are emancipated minors and thus able to legally provide consent for participation in research. Kenyan law acknowledges women ages 14 to 17 who have become pregnant as emancipated minors. The PHRD site/UW collaboration has successfully enrolled emancipated minors into a number of prior studies, including PrEP clinical trials. In addition, Kenya's national policy guidelines explicitly permit PrEP use in this age group.

Exclusion Criteria:

For peer providers (qualitative data, pilot):

• Age ≥16 or >24 years
• Male
• Have not used PrEP for a minimum of three months
• Not willing to disclose PrEP use to their peers
• Not able to identify up to 4 peers at risk of HIV infection
• Not willing to participate in training with study counselors on PrEP referral and HIVST use
• Not willing to refer peers to PrEP and deliver HIVSTs
• Not able and willing to provide written informed consent

For peer providers (cRCT):

• Age ≥16 or >24 years
• Male
• Have not used PrEP
• Currently enrolled in an HIV study
• Not able to identify up to 4 peers at risk of HIV infection
• Illiterate
• Not willing to participate in training with study counselors on PrEP referral and HIVST use
• Not willing to refer peers to PrEP and deliver HIVSTs
• Not able and willing to provide written informed consent

For peer clients (pilot, cRCT):

• Age ≥16 or >24 years
• Male
• Not referred by peer (i.e., a PrEP users) to initiate PrEP
• Not able and willing to provide written informed consent

All data (deidentified) used for primary, secondary, and other outcomes reported in the main manuscript along with a data dictionary.

September 2025 (around the time of publication). No end date.

Anyone who wishes to access the data.

Of the 395 participants we have information about, only 211 were directly enrolled in the study and provided demographic information. These enrolled participants include index peers (k) and the subset of referred peers (n) we were able to enroll and follow-up, corresponding to those who completed the study in each population group.

Adverse event data was collected for index peers at both baseline and the month 3 follow-up visit, and for referred peers at the month 3 visit (so only collected among referred peers who enrolled and completed follow-up). During data collection and study follow-up, participants were asked to report if they've had any of these events and whether they are or are not study related.

Adverse events (AEs) include any forms of verbal (e.g., yelling, fighting), physical (e.g., hitting), emotional (e.g., depression) or economic (e.g., job loss) abuse attributable to the study. While serious adverse events (SAEs) include hospitalization (for any condition, including those outside the study) or death.

Limitations included relying on index peers to report outcomes for referred peers in our primary analysis; low enrollment and follow-up among referred peers; relying on self-report for HIV testing and PrEP outcomes; and the relatively short follow-up period for all study participants (one month for pilot and three months for cRCT).