This proposed 3-arm randomized study will compare different pharmacy based approaches that include HIV prevention medication (PrEP and PEP), routine STI testing, and preventive antibiotic (doxycycline) for STIs. The study will assess how well these services can be implemented, how acceptable they are to young women, and whether they are cost-effective.

Global incidence of STIs increased over the past decade, with over one million curable STIs acquired daily. In 2020, the World Health Organization (WHO) estimated 374 million new infections of Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG), Trichomonas vaginalis (TV), and syphilis. Young women in East Africa face high prevalence of curable STIs and HIV,4 and high STI incidence. Studies confirm higher STI prevalence among younger women compared to their male peers, and older women. STIs severely affect mortality and morbidity for cisgender women by causing tubal infertility, chronic pelvic pain, pelvic inflammatory disease, ectopic pregnancy, postpartum endometriosis, adverse neonatal outcomes, and increased susceptibility to HIV. In HIV high-burden settings, cultural, economic, and social marginalization of women contributes to the risk of HIV and STIs,10 in part by making condom use negotiation challenging. Despite high STI burden in these settings, research to address STIs lags behind HIV in young cisgender women.

WHO calls for vastly increasing STI testing and integrating STI interventions to reach priority populations.Sexually transmitted infections (STIs) disproportionately affect cisgender adolescent girls and young women (AGYW) who often experience STI complications, including infertility, chronic pelvic pain, and increased risk for HIV acquisition and peripartum morbidity. In Kenya, HIV and STIs comprise a syndemic with 40% of new HIV infections occurring among AGYW. Yet, research to address STIs lags behind HIV in this priority population and no primary STI prevention tools are currently available to cisgender women beyond condoms. In Kenya, 40% of women access contraception without interfacing with facilities, including at retail pharmacies, and are missed by facility-based HIV services like pre-exposure prophylaxis (PrEP). In the ongoing work among AGYW seeking contraception at 20 pharmacies in Kisumu, Kenya (NCT05467306); all AGYW offered STI testing accepted, 29% had CT or NG, and 70% accepted expedited partner therapy (EPT) and report no social harms. Among AGYW seeking emergency contraception, only 3% previously used HIV post-exposure prophylaxis (PEP), highlighting an opportunity to offer HIV PEP to AGYW via pharmacies. Qualitative data suggest that STI testing motivates health promoting behaviors, even when STI results are negative.

To date, no studies evaluate if serial STI testing promotes PrEP persistence. 'Event-driven' doxycycline PEP (doxy-PEP) for CT, NG, and syphilis found no protective benefit for Kenyan women accessing PrEP at facilities, likely due to low adherence. AGYW more frequently access emergency contraception at pharmacies compared to facilities; thus, 'event-driven' strategies, like HIV PEP ("PEP-in-Pocket") or doxy-PEP, may have higher use in pharmacies. The investigators propose a RCT in Kisumu, Kenya-a region with 11% HIV prevalence-to test co-offering HIV PEP/PrEP and STI testing with and without doxy-PEP in pharmacies and prospectively assess HIV PEP/PrEP use and persistence, and STI incidence among AGYW (n=720) and estimate cost and cost-effectiveness of this strategy. The investigators hypothesize that expanding HIV and STI prevention options to include HIV PEP, STI testing, EPT, and doxy-PEP in pharmacies will be cost-effective and improve HIV and STI outcomes in AGYW, a population disproportionately affected by STIs and HIV. The study is designed to inform pharmacy delivery of biomedical HIV and STI prevention services and provide evidence to inform policy for STI/HIV prevention among AGYW.

Inclusion Criteria:

• Cis-gender female
• Seeking contraception (emergency contraception, oral contraceptive pills, injectables, implants, and condoms) from the retail pharmacy site
• Age ≥ 15 and <25 years old
• Willingness to receive PrEP screening per national guidelines including HIV testing
• Not currently taking PrEP
• Planning to reside in the area for the next 12 months
• Able and willing to provide informed consent for participation

Exclusion Criteria:

• Current participation in other ongoing studies.
• Medical contraindications to PrEP or doxycycline use (e.g., severe allergy to doxycycline, serious hepatic or renal disease).
• Any other condition that, in the investigator's judgment, would make participation unsafe or interfere with study procedures.

Cis-gender female