Population size, HIV prevalence, and antiretroviral therapy coverage among key populations in sub-Saharan Africa: collation and synthesis of survey data 2010-2023
Authors: Stevens Oliver , Sabin Keith , Anderson Rebecca , Garcia Sonia Arias , Willis Kalai , Rao Amrita , McIntyre Anne F. , Fearon Elizabeth , Grard Emilie , Stuart-Brown Alice , Cowan Frances , Degenhardt Louisa , Stannah James , Zhao Jinkou , Hakim Avi J. , Rucinski Katherine , Sathane Isabel , Boothe Makini , Atuhaire Lydia , Nyasulu Peter S. , Maheu-Giroux Mathieu , Platt Lucy , Rice Brian , Hladik Wolfgang , Baral Stefan , Mahy Mary , Imai-Eaton Jeffrey W. 
Published: July 2022

Background

Key population HIV programmes in sub-Saharan Africa (SSA) require epidemiologic information to ensure equitable and universal access to effective services. We consolidated survey data among female sex workers (FSW), gay men and other men who have sex with men (MSM), people who inject drugs (PWID), and transgender people to estimate key population size, HIV prevalence, and antiretroviral therapy (ART) coverage for countries in mainland SSA.

Methods

Key population size estimates (KPSE), HIV prevalence, and ART coverage data from 39 SSA countries between 2010-2023 were collated from existing databases and verified against source documents. We used Bayesian mixed-effects spatial regression to model urban KPSE as a proportion of the gender/year/area-matched 15-49 years adult population. We modelled subnational key population HIV prevalence and ART coverage with age/gender/year/province-matched total population estimates as predictors.

Findings

We extracted 2065 key population size, 1183 HIV prevalence, and 259 ART coverage data points. Across national urban populations, a median of 1.65% of adult cisgender women were FSW (interquartile range [IQR]=1.35-1.91%), 0.89% of men were MSM (IQR=0.77-0.95%), 0.32% of men injected drugs (IQR=0.31-0.34%), and 0.10% of women were transgender (IQR=0.06-0.12%). HIV prevalence among key populations was, on average, 4 to 6 times higher than matched total population prevalence, and ART coverage was correlated with, but lower than, total population ART coverage with wide heterogeneity in relative ART coverage across studies. Across SSA, key populations were estimated as 1.2% (95% credible interval [CrI]: 0.9, 1.6) of the total population aged 15-49 years but 6.1% (95% CrI: 4.5, 8.2) of people living with HIV.

Interpretation

Key populations in SSA experience higher HIV prevalence and lower ART coverage, underscoring the need for focused prevention and treatment services. In 2024, limited data availability and heterogeneity constrain precise estimates for programming and monitoring trends. Strengthening key population surveys and routine data within national HIV strategic information systems would support more precise estimates.

Funding

UNAIDS, BMGF, NIH

Research in Context

Evidence before this study

Key populations, including female sex workers (FSW), gay men and other men who have sex with men (MSM), people who inject drugs (PWID), and transgender people, are at higher risk of HIV infection, including in sub-Saharan Africa (SSA). Delivering appropriate HIV prevention and treatment services for key populations and monitoring 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 surveys, are a standard component of comprehensive national HIV surveillance.

Several complementary ongoing initiatives consolidate HIV data on key populations to support programme planning and implementation, global advocacy, and research.

These include the Key Population Atlas and Global AIDS Monitoring (Joint United Nations Programme on HIV/AIDS [UNAIDS]), databases maintained by the US Centers for Disease Control and Prevention (CDC) and The Global Fund to Fight AIDS, Tuberculosis and Malaria (The Global Fund), and the Global.HIV initiative (Johns Hopkins University). These include similar data sources, but vary in scope, inclusion criteria, data elements recorded, and linkage to and validation against primary source reports. Incomplete recording of key methodological details limits 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 comprise an appraisal of peer-reviewed literature.

Added value of this study

We consolidated and deduplicated data collected between 2010-2023 from existing key population survey databases maintained by the UNAIDS Key Population Atlas, UNAIDS Global AIDS Monitoring, US CDC, and the Global Fund. We obtained published and grey literature surveillance reports from the Johns Hopkins University Global.HIV repository, additional web-based searches, and engagement with country HIV strategic information teams, and validated each observation of key population size, HIV prevalence, or ART coverage against primary surveillance reports. We used regression to characterise 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 key population HIV data in SSA. We analysed over 3000 observations from 126 KPSE, 217 HIV prevalence, and 62 ART coverage studies. We estimated that across urban populations aged 15-49 years in SSA countries, a median of 1.65% of cisgender women were FSW; 0.89% of men have sex with men; 0.32% of men injected drugs; and 0.10% of women were transgender. This translated to 3.7 million FSW, 1.9 million MSM, 770,000 PWID, and 230,000 transgender women (TGW) in SSA who require comprehensive HIV prevention or treatment services. FSW, MSM, PWID, and TGW together were estimated as 1.2% of the population aged 15-49 years, but comprised 6.1% of people living with HIV. ART coverage among members of key populations living with HIV increased with total population ART coverage, but was lower for all key populations. We identified large gaps in data availability. Of the four key populations and three indicators studied, only Mozambique had data for all twelve indicators. Data were particularly sparse for transgender populations and PWID.

Implications of all the available evidence

Key populations experience higher HIV prevalence and lower ART coverage across all settings in sub-Saharan Africa than the total population. Extrapolated national 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 driven by discriminatory practices and punitive policies against key populations, inconsistency of existing data, and consequent wide uncertainty ranges around estimates limit the ability of existing data to guide granular programmatic planning and target setting for key population services and to monitor trends. More consistent surveillance implementation and improved routine surveillance through HIV prevention and treatment programmes for key populations would support monitoring equitable and equal programme access, as outlined in the Global AIDS Strategy 2021-2026 developed by UNAIDS, its co-sponsors, and other partners to end HIV/AIDS as a public health threat by 2030.