It is estimated that key populations, including men who have sex with men (MSM), sex workers, people who inject drugs (PWID), transgender persons, and people in prison and other closed settings and their sexual partners, account for more than half of the world’s estimated human immunodeficiency virus (HIV) infections.¹ Individuals from key populations often lack adequate access to HIV prevention and treatment services. This subsequently results in higher rates of undiagnosed HIV, leading to higher rates of morbidity and mortality in these individuals.² Key population groups accessing HIV treatment services also often experience difficulties related to viral suppression and retention into care because of issues around stigma, violence and discrimination, which impede access to health services.³

Epidemiological data on the global incidence and prevalence of HIV infection are attributed significantly to the estimates of incidence among key and vulnerable populations.⁴ The exact magnitude of this problem remains unclear because of historical lack of routine data on key population individuals. Moreover, there is growing evidence to suggest an overlapping network between key populations and the general population, indicating that HIV among key populations is not isolated, and therefore requires an urgent response in line with the existing preventive and treatment approaches within the HIV cascade.⁵ Research, globally, shows that key populations are disproportionality affected by HIV/AIDS (acquired immune deficiency syndrome) when compared to the general population.⁶ Furthermore, there are also reports of multiple sexual partners with low condom usage in most regions around the world.⁷ This subsequently results in higher rates of other sexually transmitted infections (STIs), which precipitate a long-term continuance of such infections.

There have been multiple programmatic calls to refocus prevention, treatment and care initiatives so as to comprehensively target individuals from key population groups through biomedical and preventive interventions to achieve HIV epidemic control.⁸ The foundational impediments to HIV epidemic control among key populations are accurate data on the size of these populations, their location, profile of risk behaviours per region and country, and the exact ratio of key population versus general population HIV incidence and prevalence. To achieve the Joint United Nations Programme on HIV/AIDS (UNAIDS) 95-95-95 fast-track targets, the health system must address issues related to the prevention, treatment, and care of the unique needs of key populations.⁹ Addressing the needs of key populations requires intensified programming, targeted resources allocation, and contextually relevant and responsive interventions that address and counteract the systematic marginalisation and discrimination often experienced by key populations.

The UNAIDS 95-95-95 targets on HIV/AIDS provide a road map for directing interventions to facilitate the implementation of fast-track interventions to achieve HIV epidemic control, so that HIV/AIDS is no longer a public health threat by 2030. While several interventions have been instituted with specific focus on impact strategies to halt the spread of new infections, many regions are yet to achieve the UNAIDS 95-95-95 targets. Targeted interventions for key population groups remain a key driver to facilitating realisation of epidemic control for HIV infection. The purpose of this review is thus to consolidate evidence on the fast-track interventions towards achieving HIV epidemic control among key populations. For the purpose of this review, HIV epidemic control refers to interventions or strategies to facilitate realisation of the UNAIDS 95-95-95 targets towards eliminating HIV/AIDS as a major public health threat. The UNAIDS 95-95-95 targets aim to facilitate epidemic control through fast-track interventions that call for 95% of individuals to know their HIV status through HIV testing, 95% of people to be initiated and retained on HIV treatment, and 95% to be virologically suppressed while on antiretrovirals.¹⁰

This rapid systematic scoping review maps evidence of fast-track interventions to achieve HIV/AIDS epidemic control among key population groups. The methodological framework by Arksey and O’Malley¹¹ was used to guide the review. The following steps were subsequently followed when carrying out the review: (1) identification of the review question, (2) identification of relevant studies, (3) selection of relevant studies, (4) charting of the data and (5) collating, summarising, and reporting the findings.

The initial search yielded 265 articles and no further searches were conducted thereafter. Figure 2 illustrates the search and selection process. A total of 19 articles were eventually included for this review. Appendix Table 1-A1 provides an overview of the articles and the key findings using the following headings: author, title, research objectives, country and/or region and year of publication, research methods, key findings and recommendations. Most articles included in this review were primary studies (n = 17), while others involved the review of existing literature and policies (n = 1) and routinely collected data (n = 1). Of the 19 articles included, 12 employed quantitative methods (n = 12),^{12,13,14,15,16,17,18,19,20,21,22,23} 5 used qualitative approaches (n = 5)^{24,25,26,27,28}; only one study (n = 1)²⁹ employed mixed methods approaches while yet another study comprised a review of literature and policy documents collectively (n = 1).³⁰ Most studies (n = 6) were conducted in the United States of America,^{12,13,17,22,26,28} while others were conducted in China (n = 5),^{14,15,16,21,23} Kenya (n = 2),^18,24 South Africa (n = 1),²⁰ Mozambique (n = 1),²⁹ Nigeria (n = 1),²⁵ Botswana (n = 1)²⁷ and New Guinea (n = 1).¹⁹ The remaining studies were unaccounted for in terms of country and region, as these were document reviews conducted on regional policies and research. Since the main aim of this review was mapping of evidence related to fast-track interventions to achieve HIV/AIDS epidemic control among key populations, quality appraisal of articles reviewed was not conducted.

Broadly speaking, the articles reviewed suggest that recommendations to achieve HIV epidemic control among key populations are centred on stand-alone biomedical and behavioural interventions and combination approaches, incorporating both medical and psychosocial approaches. Based on the articles reviewed, most studies reported on interventions directed towards MSM (n = 11).^{12,13,16,17,18,20,23,25,26,28} The remaining studies reported on recommendations and interventions directed towards female sex workers (n = 7),^{14,15,19,24,27,29,30} and drug users (n = 1).²¹ It was interesting to note that there were no studies reporting on the transgender population.

The aim of this scoping review was to map evidence of existing fast-track interventions to achieve HIV epidemic control among key populations. The findings of this review suggest that the effective interventions for HIV epidemic control were stand-alone behavioural preventive interventions, stand-alone biomedical preventive strategies and combination prevention approaches. Furthermore, the findings of this review imply that effective activities to achieve HIV epidemic control among key populations should be centred around preventive activities.

In the MSM population, it was found that key interventions to facilitate HIV epidemic control using behaviour modification encompassed education and health promotions approaches around the use of HIV preventive methods such as condoms, water-based lubricants and promoting HIV testing. Research on the epidemiology of HIV infection among MSM advocates that prevention strategies be formulated to prevent escalating incidences of HIV infection among this key population sub-group.^31,32 The findings of an early meta-analytic review of behaviour interventions to prevent HIV risk behaviours among MSM suggested that interventions be based on sexual risk reduction and incorporate theoretical models to include elements of interpersonal skills training, with delivery spanning multiple sessions and different delivery modalities.³³

Johnson et al.³⁴ also found that behavioural interventions to reduce risk of infection were effective interventions for HIV prevention among MSM. Typically, these strategies include reduction of unprotected sex through individualised counselling on protection against HIV and other STIs, and provision of behavioural support through peer education, relationship support, and discussions on the attitudes and beliefs around HIV preventive methods.³⁴ On the other hand, Lorimer et al.³⁵ found that group and community-level behavioural interventions for MSM are effective; however, expanding the scope of routine data indicators is required for monitoring the impact of specific behavioural interventions that are effective among MSM. Alluding to behavioural interventions to facilitate HIV prevention among MSM, Safren et al.³⁶ state that such interventions must also address the mental and psychosocial challenges that are faced by MSM, as these have an influence on sexual health behaviours that often exacerbate the risk for HIV infection.

Other behaviour modification strategies of epidemic control addressed issues of treatment compliance in men who were already HIV positive. Human immunodeficiency virus treatment as an HIV preventive strategy is another intervention that has been recommended, as supported by the universal test and treat strategy; provision of treatment adherence support was found to be an effective intervention in this regard. Study findings show that the use of innovative modalities incorporating social media and e-health approaches yields positive results in terms of fostering and maintaining adherence support, particularly among MSM youth. Hergenrather et al.³⁷ further postulate that behavioural interventions for HIV prevention among MSM should incorporate the needs of the diverse, well-educated and web-based millennial generation, and differentiate between adolescents and young adults.

For female sex workers, previous research studies show that behavioural interventions are effective in reducing HIV infection and incidences of other STIs. In this regard, social support as an intervention was found to positively correlate with the adoption of HIV prevention approaches such as condom use; more specifically, social support in the form of informational and emotional support was associated with HIV prevention. Female sex workers, co-workers and partners were instrumental in this regard. The application of cognitive behavioural theories in the promotion of condom usage and uptake yielded positive outcomes in terms of HIV risk reduction. These findings have also been shown to have similar implications for HIV reduction among people injecting drugs.^38,39,40 While behavioural interventions have been found to be effective in promoting HIV preventive behaviours such as condom use and HIV testing,⁴¹ maximising effectiveness requires sustainability which necessitates ongoing investment from government and related funding agencies.⁴²

Since stand-alone behavioural interventions are shown to be an effective strategy for HIV epidemic control among key populations, especially MSM, female sex workers and PWID, it is essential that these intervention strategies be tailored to individual needs, while also addressing the structural and systemic issues that hinder access to health service, taking cognisance of the multiple influences of access to health service at all levels in society. Since the findings of the review also suggest that stand-alone biomedical HIV preventive interventions such as Pre-exposure Prophylaxis (PrEP), non-Occupational Post Exposure Prophylaxis (Npep), condom usage and voluntary medical male circumcision are also effective approaches to achieving HIV epidemic control among MSM, female sex workers and PWID, maintaining the uptake of these services is crucial for sustained epidemic control. Research of these biomedical HIV prevention approaches has shown that understanding and addressing the contextual driver and barriers is important for maximum uptake. In the context of key population individuals, sustained uptake is also dependent on an understanding of the unique health needs of individuals who form part of key populations. Research studies on access to health services for key populations have also advocated for policy changes to facilitate inclusion of the unique needs of these individuals. Moreover, this has prompted the need for education and training of health professionals, both preservice and in-service.

In terms of biomedical HIV preventive strategies, it was found that facilitating different modelling approaches to scale up PrEP yielded tangible outcomes in terms of a reduction in new rates of infection among MSM. Early initiation of antiretroviral therapy (ART) was found to be a predictor for viral suppression in order to halt the further spread of infection. Similarly, the findings of a mathematical model of biomedical interventions for HIV prevention among MSM, in China, suggested that PrEP test and treatment, and their combinations are cost-effective and operative approaches to HIV prevention among MSM in the context of China’s HIV response strategy.⁴³ Similar studies conducted in other low-income settings also provide evidence of the effectiveness of combined PrEP and early ART initiation as preventive approaches to facilitating HIV prevention among MSM. While evidence on the aforementioned notion of combined prevention is compelling,^31,44 there is a need for interventions to be instituted to address the contextual social and structural issues that hinder uptake, and the accessibility of combined biomedical HIV preventive methods. Creating an awareness of the specific contextual psychosocial structural and systemic factors that affect MSM thus becomes imperative, and should therefore be the entry point for the creation of relevant interventions.^45,46,47 Present literature in this regard relates to issues of stigma, discrimination, racism, individual perceptual factors, community norms, values, religion, societal practices and other social injustices.^{45,47,48,49,50,51} These are key barriers hindering the uptake of these combined biomedical approaches and thus have implications for broader public health.

Facilitating the availability of nPEP was also found to be an effective strategy for HIV prevention among MSM. An early study on nPEP as a bio-behavioural HIV prevention intervention suggested that while nPEP appeared to be feasible and safe when used at community level in groups, successful integration of this strategy into existing comprehensive HIV prevention programmes was unclear.⁵² On the other hand, observational data recommends the adoption of nPEP to reduce the likelihood of HIV infection following potential exposure.⁵³ The maximum benefits of this strategy are, however, challenged by poor uptake related to acceptability and a lack of knowledge regarding this strategy, particularly among same gender loving men and the MSM population.^53,54,55

Provision of PrEP as a biomedical preventive strategy was also effective among female sex workers. Observational data has also demonstrated the effectiveness of PrEP for HIV prevention, more particularly, for key populations such as female sex workers who are at greater risk of HIV infection.^56,57 Similar to the MSM population, understanding the contextual drivers and barriers to uptake thus becomes essential for the yield of maximum benefits of this preventive approach. In this regard, understanding issues of acceptability and other psychosocial factors that are barriers to accessibility and uptake of PrEP, is vital especially among female sex workers.^58,59,60 The provision of voluntary medical male circumcision was found to be an effective biomedical preventive strategy for reducing the incidence of HIV infection among female sex workers. This finding has significant implications for public health in terms of the creation of a demand for voluntary medical male circumcision, and further concurs with previous findings on the effectiveness of medical circumcision as a biomedical HIV prevention strategy.^61,62,63

Specific interventions for HIV epidemic control for PWID are centred on biomedical preventive interventions promoting harm reduction through the provision of safe opioid substitution therapy, and facilitating the availability of needle and syringes for drug users. The needle and syringe programme reduces the chances of person-to-person spread of HIV infection by preventing drug needle sharing. This also simultaneously prevents the spread of other communicable diseases. Other studies have shown that behavioural intervention with combined harm reduction and biomedical approaches such as the provision of PrEP for PWID, are more effective for HIV prevention.^64,65,66 Success of this intervention is, however, challenged by the multiplicity of factors that hinder continued access to PrEP among PWID.⁶⁷ These factors also relate to stigma and structural issues related to legislation around PWID, particularly in low-to-middle income settings such as sub-Saharan Africa.⁶⁸ Contextual interventions for HIV prevention among PWID should therefore include targeted interventions addressing systemic and structural issues, so that tangible outputs may be attained and sustained for existing interventions.⁶⁹

Combination HIV prevention strategies for HIV epidemic control entailed the use of both behavioural and biomedical approaches, and were found to be specifically effective among MSM and female sex workers. For MSM, the studies reviewed showed that men who had been exposed to combined preventive approaches were more likely to consistently practise safe sexual intercourse by using water-based lubricants, condoms and testing regularly for HIV. For female sex workers, study findings showed that combination approaches, rooted in the provision of social support systems for sex workers, yield effective results in terms of compliance with the HIV preventive strategies such as consistent condom use and HIV testing. Specific strategies, such as the promotion of self-efficacy and HIV self-testing, were found to be acceptable and effective methods of facilitating HIV prevention, thereby resulting in epidemic control. Moreover, self-efficacy was found to be a predictor of consistent condom use among female sex workers for both stable and casual partners. There was also evidence to suggest that combination approaches targeted at female sex workers address structural issues related to legislation and health policy to prevent poor health-seeking behaviours. Specific interventions in this regard were related to the creation of sex worker-friendly facilities and cooperation between sex workers and government authorities in the design of policies for health service delivery to address the health needs of sex workers.

Broadly speaking, research advocates for combined approaches to HIV prevention among key populations.^43,70,71,72 The effectiveness of combined approaches, taking on individualised and community-based approaches encompassing behaviour and psychosocial elements, is also widely cited and suggested.^73,74,75 The concept of individualised approaches brings to light the notion of person-centred holistic and comprehensive care,⁷⁶ while the community-based approach acknowledges the role of community values, norms and attributes and how they shape health behaviour.⁷⁷ Collectively, the aforementioned issues may account for the core social determinants of health that influence health behaviour and, ultimately, health-seeking practices. This should thus be the foundation of all interventions instituted with the aim of achieving HIV epidemic control among key populations. Combined biomedical and behavioural approaches necessitate comprehensive and integrated approaches ensuring adoption and maintenance of HIV preventive methods to facilitate HIV epidemic control. This necessitates skilled health professionals to integrate multiple behavioural, psychosocial and biomedical theories and practices in the process of providing care within the recommended policy frameworks. Training of health professionals on the multiple realities of the health system and diverse health needs of individuals, especially key populations, thus becomes a crucial strategy that is required from a clinical practice perspective, health policy perspective, and from health science education perspective.

The review conducted presents major implications for clinical practice in relation to HIV epidemic control in high HIV burden regions such as South Africa, as it has provided information on the targeted and effective interventions for HIV epidemic control among key populations. The findings are based on the synthesis of evidence that is provided by the mainly primary data which demonstrates interventions and their outcomes in terms of HIV epidemic control. While the findings of the review are instrumental in guiding policy and practice interventions, certain key gaps in interventions and research are noted in this area.

It is interesting to note that, based on this review, there were no effective interventions found which targeted the transgender population. Moreover, gaps exist in the number of targeted interventions directed towards the treatment, care and retention cascade of the HIV response strategy. Other gaps as highlighted by the review related to specific effective interventions for adolescent and young adult key population groups. Interventions and related research are therefore necessary in this area. On the basis of the review results, a summary of recommendations for health policy, practice, education and research is proposed next and may be applied in high burden HIV settings like South Africa.

While this review provides evidence that has important public health and policy implications related to effective strategies for HIV epidemic control, especially for high burden HIV settings like South Africa, it is not without limitations. These relate to the nature of this systematic scoping review which was rapid in nature, with a focus on studies that had documented outcomes of effective interventions that were measured quantitatively, qualitatively and through modelling approaches. This review was also further limited by the fact that only three scholarly databases were consulted, and articles chosen were from 2014 onward, with only English articles being selected. While the findings of the review provide evidence to inform practice, findings are limited because of the aforementioned limitations. Nonetheless, the findings highlight important interventions to be considered and point to possible gaps to be addressed by policy, practice and research in the quest to achieve HIV epidemic control among key populations. The findings and related implications are additionally important for high HIV burden settings like South Africa, where the HIV response strategy is committed to achieving HIV epidemic control with a special focus on key populations.

The findings of this review revealed that the key effective strategies for achieving HIV epidemic control among key populations centre on stand-alone, behavioural and biomedical interventions, and combination prevention approaches. In this regard, the findings imply that achieving HIV epidemic control among key populations should centre on prevention strategies. The findings do, however, show gaps in research and effective interventions targeting transgender individuals and people injecting drugs. The review further highlights the lack of effective interventions related to the treatment and care cascade. Lastly, the findings of this review also suggest that achieving HIV epidemic control among key populations is reliant on combined strategies that simultaneously address the structural, systemic and psychosocial barriers hindering access to healthcare.