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

Introduction Nairobi County has the largest HIV prevention programme for female sex workers (FSW) and men who have sex with men (MSM) in Kenya. Routine monitoring of programme outcomes is critical for tracking progress toward programme targets. Monitoring approaches need to be rapid, affordable, and sufficiently robust to capture programme outcomes while meaningfully involving communities. Methods We conducted a cross-sectional outcome assessment among FSW and MSM (71% reporting sex work) in Nairobi County from April–July 2023 using an expanded polling booth survey (ePBS). The ePBS combined anonymous group-level polling booth survey (PBS) with an individual biobehavioural survey (BBS) to assess behavioural, structural and biological outcomes. Weighted descriptive analyses summarised programme outcomes. Results The target sample size for the study was 769 FSW and 420 MSM. Overall, 759 FSW (response rate 98.6%) and 398 MSM (response rate 94.7%) participated in 64 PBS sessions; 758 FSW completed the BBS, while 398 MSM completed the behavioural component and 396 completed the biological component. Condom use at last sex was reported by 80.8% of FSW with paying clients and by 72.7 and 68.9% of MSM with non-regular partners and paying clients, respectively. Recent peer educator contact was reported by 68.8% of FSW and 65.8% of MSM. Healthcare-related stigma was reported by 8.0% of FSW and 7.5% of MSM, and recent forced sex by 10.7% of FSW and 6.5% of MSM. HIV prevalence was 14.0% among FSW and 18.6% among MSM. Among participants living with HIV, 85.9% of FSW and 80.4% of MSM were virally suppressed. Among those reporting current oral PrEP use, tenofovir was detected in urine among 48.3% of FSW and 52.6% of MSM. Conclusion FSW and MSM in Nairobi remain priority populations for the HIV response. The findings suggest persistent gaps across behavioural, structural and biomedical outcomes that need to be addressed. The ePBS approach offers a practical and scalable method for generating actionable outcome data that can complement routine monitoring systems and support adaptive HIV programming. As countries face increasing pressure to optimise HIV programmes within constrained funding environments, approaches that generate timely and actionable outcome data will become increasingly important.