Integrating Sexually Transmitted Infection Testing into Pharmacy-Based HIV Prevention for Adolescent Girls and Young Women in Kenya: Epidemiology, HIV Pre-Exposure Prophylaxis, and Sexual and Reproductive Health Service Delivery

Abstract

Adolescent girls and young women (AGYW) in sub-Saharan Africa experience a substantial burden of sexually transmitted infections (STIs) and HIV. Curable STIs, including chlamydia, gonorrhea, and trichomoniasis, are frequently asymptomatic and may remain undiagnosed in settings where STI services rely primarily on syndromic management. Untreated infections can result in pelvic inflammatory disease, infertility, adverse pregnancy outcomes, and increased susceptibility to HIV acquisition. In Kenya, AGYW frequently obtain contraception and other sexual and reproductive health services from retail pharmacies because pharmacies offer convenient locations, flexible operating hours, privacy, and shorter waiting times than health facilities. Retail pharmacies are also emerging as delivery platforms for HIV pre-exposure prophylaxis (PrEP). Integrating etiologic STI testing into pharmacy-based PrEP delivery could provide AGYW with more comprehensive, person-centered sexual and reproductive healthcare. However, evidence is limited regarding the burden and incidence of STIs among AGYW accessing pharmacies, the relationship between STI testing and PrEP engagement, and AGYW experiences with integrated pharmacy-based STI and HIV prevention services.To address these gaps, this dissertation pursued three objectives: 1) to estimate the prevalence and identify correlates of chlamydia, gonorrhea, and trichomoniasis among AGYW purchasing contraception at retail pharmacies and assess STI treatment and expedited partner therapy outcomes; 2) to estimate STI incidence among AGYW offered pharmacy-based HIV PrEP and examine associations among STI testing, STI diagnosis, and PrEP initiation and continuation; and 3) to characterize AGYW experiences with the co-delivery of STI testing and HIV PrEP at retail pharmacies and identify considerations for implementing integrated services. The three studies were nested within a cluster-randomized trial comparing standard pharmacy-based PrEP delivery with an enhanced nurse-navigator model at 25 retail pharmacies in Kisumu County, Kenya. The parent trial enrolled AGYW aged 15–24 years who were purchasing contraception and willing to discuss HIV PrEP. Participants were offered daily oral PrEP or the dapivirine vaginal ring and followed for 10 months. Testing for chlamydia, gonorrhea, and trichomoniasis using Xpert® nucleic acid amplification assays was implemented at a subset of 11 pharmacies. For the first study, we conducted a cross-sectional analysis of enrollment data to estimate STI prevalence and identify demographic, behavioral, psychosocial, and sexual and reproductive health correlates of infection. Among 701 AGYW offered STI testing, 682 completed chlamydia and gonorrhea testing, of whom 640 also completed trichomoniasis testing. Among participants tested for all three infections, 28.0% had at least one STI. Chlamydia prevalence was 21.4%, gonorrhea prevalence was 5.4%, and trichomoniasis prevalence was 7.5%. Among participants with at least one laboratory-confirmed STI, 76% reported no STI symptoms, demonstrating that reliance on symptom-based screening would have missed most infections. Correlates differed across pathogens. Chlamydia prevalence was nearly twice as high among AGYW reporting intimate partner violence than among those who did not report violence. Gonorrhea prevalence was substantially higher among participants residing in rural than urban areas, and trichomoniasis prevalence was higher among participants reporting recent alcohol use. Among 190 AGYW diagnosed with at least one STI based on available testing results, 90% received treatment. Most treated participants accepted expedited partner therapy, but only 47% of all participants diagnosed with an STI reported that their partners had completed treatment by the one-month visit. These findings demonstrate a high burden of predominantly asymptomatic STIs among AGYW accessing contraception at retail pharmacies and identify opportunities to strengthen partner notification and treatment services. For the second study, we conducted a prospective observational analysis to estimate cumulative STI incidence over 10 months and examine relationships between STI testing and HIV PrEP engagement. The overall analysis included 1,855 AGYW without HIV, of whom 63.1% initiated PrEP by the one-month visit. PrEP initiation did not differ significantly between participants who did and did not complete STI testing at enrollment. Among PrEP initiators, continuation at 10 months was also similar by enrollment STI testing status and by whether participants were diagnosed with an STI at enrollment. Among 180 participants who tested negative for chlamydia, gonorrhea, and trichomoniasis at enrollment and completed testing for all three infections at 10 months, 15.0% acquired at least one incident STI. Cumulative incidence was 13.0% for chlamydia, 3.4% for gonorrhea, and 1.8% for trichomoniasis. More than three-quarters of incident infections were asymptomatic. STI incidence was higher among AGYW who had ever initiated PrEP than among those who had never initiated PrEP, although this finding likely reflects greater underlying sexual risk among AGYW who chose PrEP rather than a causal effect of PrEP use on STI acquisition. STI incidence did not differ between AGYW who continued and discontinued PrEP at 10 months. These findings show that AGYW remain at substantial risk of acquiring STIs after enrollment and support routine repeat STI testing as a component of pharmacy-based HIV prevention services. For the third study, we conducted 10 focus group discussions with 70 AGYW enrolled in the parent trial to explore experiences with and perceptions of integrated STI testing and HIV PrEP delivery. Participants were purposively sampled to represent variation in PrEP acceptance, method choice, continuation, and STI testing experience. Data were analyzed thematically using a combined deductive and inductive approach guided by the Proctor Implementation Outcomes Framework. Thirty-one participants were enrolled at pharmacies offering STI testing, and all accepted testing when offered. Among the 18 participants tested for all three STIs, 22% were diagnosed with at least one infection. Participants described pharmacy-based STI testing as highly acceptable because pharmacies offered privacy, convenience, reduced anticipated stigma, and “one-stop” access to contraception, HIV prevention, and STI services. Testing was viewed as feasible because specimen collection was straightforward, results were returned promptly, and treatment could be obtained through the study. Respectful and supportive pharmacy providers and nurse navigators contributed to satisfaction and patient-centeredness. STI testing also shaped HIV risk perception and PrEP decision-making. Some participants reported that testing encouraged PrEP initiation or continuation and reinforced other preventive behaviors, even when STI results were negative. However, confusion between possible STI symptoms and perceived side effects of the dapivirine vaginal ring occasionally contributed to concerns about continued ring use. Participants recommended affordable or subsidized testing, private service spaces, provider-initiated offers of testing, community education, and communication through text messages and social media. Together, these studies demonstrate that retail pharmacies reach AGYW with substantial unmet STI prevention, diagnostic, and treatment needs. Both prevalent and incident infections were common and predominantly asymptomatic, underscoring the limitations of syndromic management and one-time screening. Although access to PrEP did not eliminate STI risk, STI testing and diagnosis did not appear to discourage PrEP initiation or continuation. Instead, AGYW perceived integrated STI testing and PrEP delivery as acceptable, feasible, confidential, and responsive to their sexual and reproductive health needs. These findings support the integration of routine etiologic STI testing, repeat screening, treatment, partner services, risk-reduction counseling, and HIV PrEP within pharmacy-based service delivery models. Successful implementation will require affordable diagnostics, private testing spaces, trained and supportive providers, reliable systems for returning results and delivering treatment, strengthened partner-management approaches, and coordination with national HIV and STI programs. Expanding integrated services through retail pharmacies could provide a person-centered strategy for improving access to comprehensive sexual and reproductive healthcare among AGYW in Kenya.