Introduction

HIV pre-exposure prophylaxis (PrEP) has become a crucial component of global HIV prevention strategies, particularly for female sex workers (FSWs) and other populations at increased risk for HIV acquisition [1–3]. In 2022, the relative risk of acquiring HIV was nine times higher for sex workers than in the wider adult (aged 15–49 years) population globally [4]. Daily oral tenofovir and co-formulated emtricitabine-tenofovir disoproxil fumarate (FTC/TDF) have been shown to significantly reduce the incidence of HIV [5]. Specifically, studies conducted among heterosexual men and women in Uganda and Kenya demonstrated a 67% reduction in HIV incidence with daily oral tenofovir, and a 75% reduction with co-formulated FTC/TDF [5]. The implementation and adherence to PrEP among FSWs, holds promise in the quest to end the HIV epidemic, particularly in sub-Saharan Africa (SSA), the region most heavily affected by HIV [6–8]. In 2022, sex workers accounted for an estimated 5.2-15% of new HIV infections in SSA [9]. Importantly, FSWs act as a bridge population - up to 15% of HIV infections in the general adult female population are attributable to sex work [3]. In Uganda, FSWs exhibit a high HIV prevalence, ranging from 31% to 52%, and account for 7-11% of new HIV infections [10,11].

Studies across SSA have reported high acceptability of PrEP among FSWs, ranging from 53% to 98% across different regions [12–15]. Surveys in Nigeria, Tanzania, and Uganda reported high willingness to use PrEP among FSWs, with 91% in Nigeria, 98% in Tanzania, and 91% in Uganda expressing interest [12,14,15]. In contrast, a survey in Ghana reported a lower willingness to use PrEP among FSWs, with only 53.9% expressing interest [13].

In Uganda, oral PrEP roll-out among HIV-negative persons at increased risk of HIV acquisition, including FSW, started in July 2017 [16]. While PrEP acceptability among FSWs in Uganda and SSA has been well-documented, data on PrEP use outside demonstration projects remains limited. Most studies on PrEP have focused on initiation, with many conducted within the context of PrEP demonstration projects. These projects aim to introduce PrEP in real-world settings, assess its feasibility and effectiveness, and identify implementation challenges [14,17–19]. However, there is a need for more research on PrEP use among the general FSW population. This study aimed to assess current oral PrEP use and associated factors among FSWs in two Ugandan cities.

Methods

Results

A total of 236 FSW were included in the analysis, with a median age of 27 years (interquartile range [IQR] 23-31) in Mbale and 26 years (IQR 22-30) in Mbarara. Their demographic characteristics were broadly similar between the two cities, except for the average number of clients per week and marital status (Table 1). The median duration in sex work was respectively 38 months in Mbale and 36 months in Mbarara. FSWs in Mbale reported a significantly higher number of clients per week, with a median of 25 compared to 15 in Mbarara. In both cities, over three quarters of the FSW had obtained either primary or secondary level of education, with 85% in Mbale and 82% in Mbarara having attained this level. Marital status significantly differed between the cities, with most FSWs in Mbale identifying as single (61%) and most in Mbarara describing themselves as separated (54%). The main venues for soliciting clients were similar, with streets, lodges, and bars/clubs being the most common in both cities.

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Table 1. Characteristics of FSW enrolled in the survey stratified by city.

https://doi.org/10.1371/journal.pone.0320065.t001

Significant variations were observed among FSWs in Mbale and Mbarara regarding condom use, syphilis and HIV testing, PEP and PrEP awareness and usage (p < 0.001 for all comparisons) (Table 2). Compared to Mbale, FSWs in Mbarara reported higher rates of recent syphilis and HIV testing. Lifetime syphilis testing was significantly higher in Mbarara (90%) than in Mbale (61%), with recent testing (within the past three months) also more common in Mbarara (81%) than in Mbale (26%). Although lifetime HIV testing rates were similar between the two sites (Mbarara: 97%, Mbale: 93%), recent HIV testing was more frequent in Mbarara (82%) than in Mbale (52%).

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Table 2. Condom use, STI/HIV testing behaviours, and PrEP use stratified by city.

https://doi.org/10.1371/journal.pone.0320065.t002

Awareness and use of PrEP remained low in both cities; however, these percentages were higher in Mbarara with 67% awareness, 23% ever using PrEP, and 17% currently using it compared to Mbale with only 33%, 9%, and no current users respectively. Also, PEP awareness and use were lower in Mbale (awareness: 45%, use: 8%) compared to Mbarara (awareness: 66%, use: 15%).

After adjusting for age, marital status, clients per week, and condom use frequency in multivariate analysis, residing in Mbarara (adjusted prevalence ratio [aPR] 2.33; 95% confidence interval (CI) 1.19–3.97; p = 0.01) and attaining secondary education (aPR 2.50; 95% CI: 1.14–5.45; p = 0.02), or tertiary education (aPR 3.12; 95% CI: 1.09–8.96; p = 0.03) were associated with current PrEP use (Table 3).

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Table 3. Factors associated with PrEP use among FSW.

https://doi.org/10.1371/journal.pone.0320065.t003

Discussion

This cross-sectional study investigated current oral PrEP use among FSWs in two Ugandan cities. Less than half (42.3%) of the FSWs reported being aware of oral PrEP, with only 9.7% reporting current use. However, awareness and use significantly varied by location. Notably, FSWs who had attained secondary or tertiary education were 2.5-3 times more likely to report current use, consistent with previous studies conducted in SSA [26–28]. These studies have consistently shown a positive correlation between education level and PrEP usage, highlighting the need for implementation research on strategies to promote PrEP use among FSWs with lower education levels.

Our finding that FSWs in Mbarara were twice as likely to be aware of PrEP and report current use compared to those in Mbale highlights limited awareness and uptake in certain Ugandan urban locations. This disparity may be attributed to Mbarara’s high adult HIV prevalence (14.4% vs 5.4% in Mbale) [10], which has likely fueled ongoing HIV-focused research and increased community-level awareness of HIV prevention [29,30]. Furthermore, the presence of a PrEP demonstration project targeting women at increased risk of HIV acquisition in Mbarara may also contribute to the observed difference [30]. Targeted educational campaigns to FSWs regarding the benefit and availability of oral PrEP services are still needed.

Regional variations in PrEP usage have been observed among FSWs in East Africa. While our finding of low current PrEP use (9.7%) is comparable to a Kenyan study (24%) [26], a recent Tanzanian study reported notably higher use (97%) [27]. These disparities likely stem from contextual differences in service organization, provider characteristics, and recipient factors. Existing literature cites various barriers to non-oral PrEP use among FSWs, including limited access, lack of awareness, negative perceptions, stigma, and pill burden [26,31,32]. Despite these insights, targeted interventions are still necessary to improve PrEP uptake and usage.

This cross-sectional study, conducted prior to the first COVID-19 lockdown in Uganda, provides a snapshot of PrEP use among FSWs in Mbale and Mbarara. However, the findings may not capture trends in PrEP use over time. Additionally, self-reported PrEP use may be subject to social desirability bias. Moreover, the study’s sample was limited to two cities and may not be generalizable to all FSW communities in Uganda. Furthermore, peer referrals, a non-random sampling strategy was used to enroll study respondents. Despite these limitations, the results highlight the need for targeted educational campaigns and implementation studies to increase PrEP uptake among FSWs, particularly in areas with low awareness and usage beyond demonstration projects.

Conclusions

The low PrEP usage in this FSW cohort underscores the need for implementation studies that evaluate strategies to improve uptake, particularly among those with lower levels of education.

Supporting information

Acknowledgments

Richard Muhindo is a Fogarty UCGHI GloCal Fellow supported by the Fogarty International Center of the National Institutes of Health (NIH) and the University of California Global Health Institute (UCGHI). We extend our sincere gratitude to the leadership of the cities of Mbale and Mbarara for their support and facilitation of the data collection process. Additionally, we acknowledge the contributions of Collins Twesigye and Jonan Mweteise, who served as research assistants.