Key population size, HIV prevalence, and ART coverage in sub-Saharan Africa: systematic collation and synthesis of survey data

Background HIV programmes in sub-Saharan Africa (SSA) require information about HIV among key populations to ensure equitable and equal access to HIV prevention and treatment. Surveillance has been conducted among female sex workers (FSW), men who have sex with men (MSM), people who inject drugs (PWID), and transgender populations, but is not systematically included in national HIV estimates. We consolidated existing KP surveys to create national-level estimates of key population size, HIV prevalence, and ART coverage for mainland SSA. Methods Key population size estimates (KPSE), HIV prevalence, and ART coverage data from 38 countries from 2010-2021 were collated from existing databases, deduplicated, and verified against primary sources. We used Bayesian mixed-effects regression to spatially smooth KPSE, and regressed subnational key population HIV prevalence and ART coverage against age/sex/year/province-matched total population estimates. Findings We extracted 1449 unique KPSE datapoints, 1181 HIV prevalence datapoints, and 242 ART coverage datapoints. Countries had data for a median of five of the twelve population/outcome stratifications. Across countries, a median of 1.44% of urban women were FSW (interquartile range [IQR] 0.83-1.89%); 0.60% of urban men were MSM; and 0.16% of urban adults injected drugs (IQR 0.14-0.24%). HIV prevalence in all key populations was higher than matched total population prevalence. ART coverage was correlated with, but lower than, total population ART coverage. Across SSA, key populations were estimated as 1.1% (95%CI 0.7-1.9%) of the population but 5.1% (95%CI 3.2-10.3%) of all PLHIV aged 15-49 years. Interpretation Key populations in sub-Saharan experience disproportionate HIV burden and somewhat lower ART coverage, underscoring need for focused prevention and treatment services. However, large heterogeneity and incomplete data availability limit precise estimates for programming and monitoring trends. Future efforts should focus on integrating and strengthening key population surveys and routine data within national HIV strategic information systems. Funding UNAIDS Evidence before this study Key populations (KPs), including female sex workers (FSW), men who have sex with men (MSM), people who inject drugs (PWID), and transgender women (TGW), are disproportionately vulnerable to HIV in sub-Saharan Africa (SSA). Delivering appropriate HIV prevention and treatment programming for these populations, and monitoring attainment of an equitable HIV response, requires robust information on key population size, HIV prevalence, the treatment cascade, and new HIV infections. For this reason, key population surveys including population size estimation and bio-behavioural survey are a standard component of a comprehensive national HIV surveillance portfolio, Several organisations have initiatives to consolidate HIV data about key populations for global monitoring, programme planning, and research purposes. These include the Joint United Nations Programme on HIV/AIDS (UNAIDS) Key Population Atlas, UNAIDS Global AIDS Monitoring submissions, the US Centers for Disease Control and Prevention (CDC), the Global Fund Against TB, AIDS, and Malaria (GFTAM), and the Johns Hopkins University Global.HIV initiative. Existing initiatives include much overlap of data, but vary in scope, inclusion and exclusion criteria, data elements recorded, and linkage to and validation against primary source data sets and reports. Omission or incomplete recording of key methodological details inhibits appraisal and formal evidence synthesis, and therefore utility of data for strategic planning. Many other research studies have systematically reviewed, analysed, and extrapolated key population survey data in sub-Saharan Africa in single countries or across multiple countries. These studies have tended to focus on specific outcomes or population groups of interest and primarily reviewed peer-reviewed literature. Added value of this study We consolidated and deduplicated data from 2010-2021 from existing key population surveillance databases maintained by the UNAIDS Key Population Atlas, UNAIDS Global AIDS Monitoring (GAM), the US CDC, GFTAM. We used the Johns Hopkins University Global.HIV repository of surveillance reports and additional web-based searches, and engagement with in-country HIV strategic information teams to source primary sources in the peer-reviewed and grey literature, and validated each observation of KP population size, HIV prevalence, or ART coverage against primary surveillance reports. Using regression, we characterised the relationship between key population and total population HIV indicators and extrapolated key population size estimates (KPSE), HIV prevalence, and ART coverage data to national-level estimates for all countries in mainland SSA. This exercise was the most comprehensive effort to date to consolidate KP HIV data in SSA. We analysed 90 KPSE, 159 HIV prevalence, and 72 ART coverage studies. We estimated that across SSA countries, a median of 1.44% of urban women were FSW; 0.60% of urban men have sex with men; and 0.16% of urban adults injected drugs. Though FSW, MSM, and PWID combined were estimated as only 1.1% of the population they comprised 5.1% of all people living with HIV aged 15-49 years. KP ART coverage increased consistently with total population ART coverage, but lagged behind at high population coverage levels. We identified large gaps in data availability. Of the four KPs and three indicators studied, only Kenya and Mozambique had data for all twelve indicators. Data were particularly sparse for PWID in Southern Africa. Implications of all the available evidence Consolidated data show that key populations, including FSW, MSM, PWID, and TGW, experience disproportionate vulnerability to HIV and lower ART coverage across all settings in sub-Saharan Africa. This evidence along with synthesised extrapolated estimates provide a foundation for planning appropriate key population focused services for HIV prevention and treatment in all settings, including those with no or limited data. However, large data availability gaps, large heterogeneity, and inconsistency of existing data, and associated wide uncertainty ranges in resulting estimates limits the ability of existing data to guide granular programmatic planning and target setting for KP services or robustly monitor trends. New strategies and more consistent surveillance implementation are required credibly to monitor equitable and equal access to HIV prevention and treatment programmes outlined in the Global AIDS Strategy 2021-2026 in order to end HIV/AIDS as a public health threat by 2030. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This research was supported by UNAIDS and the MRC Centre for Global Infectious Disease Analysis (reference MR/R015600/1), jointly funded by the UK Medical Research Council (MRC) and the UK Foreign, Commonwealth & Development Office (FCDO), under the MRC/FCDO Concordat agreement and is also part of the EDCTP2 programme supported by the European Union. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Source data were publicly available and included as supplementary file in submission I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes All survey data produced in the present work are contained in the supplementary materials All remaining data are available upon reasonable request to the authors