The study targeted a significant population, aiming for 769 FSW and 420 MSM. Ultimately, 759 FSW (with a response rate of 98.6%) and 398 MSM (with a response rate of 94.7%) participated in the 64 and 35 planned PBS sessions, respectively. For the BBS component, 758 FSW and 398 MSM completed the behavioral survey, while 396 MSM completed the biological component, indicating high engagement across the study components. The findings reveal that HIV prevalence remains a significant concern, standing at 14.0% among FSW and 18.6% among MSM. However, the overall prevalence rates underscore the ongoing need for intensified prevention efforts within these communities.

Behavioral outcomes presented a mixed picture of knowledge and practice. A high percentage of participants reported having knowledge regarding the increased risk of HIV transmission when engaging in unprotected sex, with 87.3% of FSW and 87.9% of MSM possessing this knowledge. Furthermore, contact with a peer educator in the previous three months was reported by 68.8% of FSW and 65.8% of MSM. Yet, significant gaps persist in consistent prevention practices. Condom use at last sex with a paying client was reported by 80.8% of FSW and 68.9% of MSM. However, nearly half of FSW (47.9%) reported having sex with a paying client without a condom in the previous three months, and 56.1% of MSM reported similar unprotected sex with a sexual partner. A major structural barrier identified was the limited availability of prevention commodities; 39.8% of FSW and 49.1% of MSM reported wanting to use a condom in the previous month but being unable to do so because they were unavailable at the time and place needed. Similarly, 53.5% of MSM cited the unavailability of lubricants as a barrier.

The structural outcomes of the assessment painted a complex picture of the social determinants of health affecting FSW and MSM. While stigma and discrimination from health service providers were reported by a small minority (8.0% of FSW and 7.5% of MSM), stigma originating from family or community members was much more prevalent, reported by 25.6% of FSW and 24.1% of MSM. Violence and police harassment also posed serious threats; 19.3% of FSW and 8.3% of MSM reported being arrested or physically assaulted by police or city askaris in the previous three months while engaging in sex work or due to their status. Furthermore, 10.7% of FSW and 6.5% of MSM reported experiencing physically forced sex within the last three months. Despite these high rates of violence and discrimination, the study noted that approximately half to three-fifths of participants who experienced such incidents reported receiving support from the program, suggesting that while services exist, they may not be universally accessible or adequately utilized in crisis situations.

Biomedical and laboratory-based outcomes provided crucial insights into the utilization and effectiveness of medical interventions. Nearly all participants reported ever having an HIV test (96.9% of FSW and 93.0% of MSM), demonstrating high historical engagement with the healthcare system. However, the rate of testing within the previous three months was lower, at 61.7% for FSW and 57.1% for MSM, which is below national recommendations for quarterly testing. Regarding oral PrEP, self-reported use was 28.3% among FSW and 21.1% among MSM. More critically, the study employed a validated urine tenofovir assay to objectively measure adherence. Of those reporting current oral PrEP use, tenofovir was detected in urine in 48.3% of FSW and 52.6% of MSM. This objective metric revealed a significant discrepancy between self-reported adherence and actual drug detection, suggesting challenges with consistent use or adherence among those prescribed PrEP, which is a critical finding for optimizing biomedical interventions.

The ePBS methodology itself proved highly valuable in capturing this nuanced data. The use of weighting procedures was essential to account for the unequal probability of selection across different locations, ensuring the estimates accurately reflected the underlying FSW and MSM populations. The combination of the anonymous group-level PBS and the individual-level BBS allowed researchers to gather both broad programmatic trends and specific biological data, providing actionable intelligence that complements routine monitoring systems. The ability to incorporate community members into the entire knowledge generation and utilization cycle—from tool design to interpreting findings—is highlighted as a key strength of the ePBS approach, shifting monitoring from mere performance reporting to active service improvement.

The findings collectively underscore that FSW and MSM in Nairobi face multifaceted vulnerabilities that require integrated and differentiated responses. The structural barriers, such as the unavailability of essential prevention commodities like condoms and lubricants, are not merely individual behavioral issues but systemic failures in supply chain and resource allocation. Addressing these gaps requires more than just increasing awareness; it necessitates robust, reliable access to prevention tools and a comprehensive service delivery model that includes mental health support and protection against violence.

Looking forward, the study identifies several limitations, notably the cross-sectional nature of the data, which precludes causal inference, and the reliance on self-reported data for sensitive topics. Furthermore, the focus on physical solicitation locations may underrepresent the experiences of individuals who primarily use virtual platforms, a demographic that requires specific attention in future research to ensure comprehensive coverage. However, the ePBS framework itself offers a scalable and practical model for generating timely data in constrained funding environments. By integrating behavioral, structural, and biological outcomes, this approach provides the evidence base necessary for adaptive HIV programming, allowing health authorities to move beyond general service delivery metrics toward targeted interventions that address the specific, complex needs of key populations in Nairobi.

Subject of Research: Assessment of HIV prevention and treatment outcomes among key populations in Nairobi, Kenya, using an expanded polling booth survey.

Article Title: Expanded polling booth surveys monitor HIV programme outcomes among female sex workers and men who have sex with men in Nairobi, Kenya

Article References: Bhattacharjee, P., Isac, S., Kimani, J., Emmanuel, F., Kabuti, R., Kinyua, A., Ndukuyu, V. N., Musyoki, H., Kiplagat, A., Arimi, P., Shaw, S. Y., Gandhi, M., Blanchard, J., Becker, M. L., & McClarty, L. M. (2026). Expanded polling booth surveys monitor HIV programme outcomes among female sex workers and men who have sex with men in Nairobi, Kenya. Frontiers in Public Health, 14, Article 1969489. https://doi.org/10.3389/fpubh.2026.1969489

Image Credits: AI Generated

DOI: 10.3389/fpubh.2026.1969489

Keywords: HIV, Key Populations, Nairobi, Public Health, Polling Booth Survey, PrEP, Behavioral Health, Structural Violence, Expanded, polling, booth, surveys