What We Know

Measuring the Potential Impact of Combination HIV Prevention in Sub-Saharan Africa

Khademi, A., Anand, S., and Potts, D., Medicine (September 2015), 94(37): e1453, doi: 10.1097/MD.0000000000001453.

The authors of this article reported on an HIV transmission model developed to assess the impacts of universal access to treatment, combined with scale-up of HIV education. The authors defined universal access to treatment as coverage of at least 80 percent of the population needing treatment, and considered HIV education inclusive of adherence to partner reduction and condom use. The analysis reported in this article focused on South Africa and examined the impact of two interventions on prevalence, incidence, and HIV-related deaths over 15 years. Findings showed that implementing the interventions in combination had a significantly larger impact (74% decrease in incidence over 15 years) than the sum of the impacts of implementing the two interventions individually (43% for universal access to treatment and 8% for scale-up of HIV education). Based on this model, the authors concluded that comprehensive combination HIV prevention could have a larger effect than disparate separate prevention interventions.  They recommended that policymakers planning combination prevention programs in sub-Saharan Africa prioritize achieving rapid universal access to treatment and improving condom use.

Combination HIV Prevention: Tailoring and Coordinating Biomedical, Behavioural and Structural Strategies to Reduce New HIV Infections, A UNAIDS Discussion Paper

Joint United Nations Programme on HIV/AIDS (UNAIDS). (2010).

This discussion paper outlines the advantages of implementing a combination prevention approach by using the synergies of behavioral, biomedical, and structural interventions. While there have been notable declines in HIV prevalence and incidence linked to behavioral changes in the population, improving these trends will require support for larger and more effective prevention programs. The paper defines combination prevention and outlines necessary steps for planning and implementing a coherent, evidence-informed, and rights-based approach. For planning, the paper highlights using an inclusive, transparent, evidence-informed process; identifying modes of transmission, geographic patterns, and populations; and developing a national plan for combination prevention. Implementation requires understanding and addressing political and capacity barriers and simutaneously working on coordination, quality, and efficiency.Finally, effective implementation requires investments in monitoring and evaluation. Combination prevention is an attempt to address not just the individual causes of vulnerability, but also the underlying social, cultural, legal, and structural causes. This approach requires identification of local solutions and development of coordinated, synergistic, and evidence-based responses; these must be both strategic and sustainable if they are to reach the goal of zero new infections found in many national HIV strategic plans.

Combination Implementation for HIV Prevention: Moving from Clinical Trial Evidence to Population-Level Effects

Chang, L.W., Serwadda, D., Quinn, T.C. et al. The Lancet Infectious Diseases (January 2013), 13(1): 65–76, doi: 10.1016/S1473-3099(12)70273-6. 

The authors of this review article argued that in addition to combination prevention, “combination implementation” is needed to realize substantial reduction in HIV incidence. They defined combination implementation as practical, specific use of evidence-informed approaches to support high, ongoing uptake and quality of HIV prevention interventions. The review outlined how cross-cutting strategies like task shifting, structural interventions, and demand creation can work with a range of specific interventions, including HIV testing and counseling, behavior change and condom promotion, linkage and retention in care, and voluntary medical male circumcision, among others. The article included a brief section examining the implications for key populations. The authors acknowledged that there is limited evidence on many of the individual interventions and strategies, and on the impact of implementing them in combination. However, they maintained that there is sufficient evidence to guide early interventions, and argued for rigorous implementation science and operational research to assess the impact and inform future combination prevention activities. They recommended using mixed methods for such assessments, and monitoring for potential synergistic or antagonistic effects; and cautioned that programs would need to be flexible to adapt to the findings of the assessments. They also noted that evaluation, implementation, and scale-up of combination prevention will require substantial investment. 

Combination Prevention: A Deeper Understanding of Effective HIV Prevention

Hankins, C. A., & de Zalduondo, B. O. AIDS (2010), Vol. 24 (suppl 4), pp. S70–S80.

This paper provided an overview of combination prevention programs and described how to design and implement them to match each country’s unique social and epidemiological context. The authors underscored HIV prevention as a mainstay in the HIV response, and vital to keeping the epidemic at bay. They gave a historical perspective of HIV prevention and described how the field evolved into its current focus on combination prevention programs. Planning combination prevention programs begins with the “know your epidemic, know your response” motto devised by the Joint United Nations Programme on HIV/AIDS. Knowing your epidemic entails asking where the next 1,000 infections will come from instead of focusing on past prevalence rates. Knowing your response focuses on designing strategies by comparing predicted new infections to the current activities being implemented, to perform a gap analysis. The results of the gap analysis can help programmers develop a tailored approach appropriate for the social, cultural, and epidemiological context of a country, region, district, and/or community. The authors added that the evidence base for combination prevention programs is weak; investing in impact research and implementation science is vital to continue to refine and improve programs. They concluded by stating that long-term strategies, tailored to the immediate causes of vulnerability and underlying risk of populations, are necessary to curb the rate of the epidemic's growth.

Investigating Combination HIV Prevention: Isolated Interventions or Complex System

Brown, G., Reeders, D., Dowsett, G.W., et al. Journal of the International AIDS Society (December 2014), 18: 20499, doi: 10.7448/IAS.18.1.20499. 

The authors of this commentary drew on a scoping study of 496 published articles on combination prevention to identify gaps and inform future research to meet the ambitious 90-90-90 targets set in 2014 by the Joint United Nations Programme on HIV/AIDS (UNAIDS). They defined combination prevention as evidence-informed, simultaneous use of behavioral, biomedical, and structural HIV prevention strategies that are both synergistic and adaptable. The scoping study found that HIV prevention evaluation centered on three main themes: individual behavior change; isolated interventions; and limited implementation experience that allowed for adaptation. The authors noted that research on HIV prevention interventions generally looked at one intervention at a time, with little attention to the context, and that simply adding interventions missed opportunities to assess synergies that may accompany more strategic packaging. They said that gaps remained in evidence to inform strategic configuring of combination prevention; and urged recognition of combination prevention as a complex system whose interactions can amplify or multiply effects. Systems science approaches could offer analytic tools to assess these dynamics. The authors noted that partnerships are also vital to addressing the political and policy challenges of understanding these complex dynamics and using the evidence generated. Realizing the synergies needed to meet UNAIDS' bold agenda will require investment in systems approaches, partnerships, and openness to applying evidence to inform programs. 

Economics of Antiretroviral Treatment vs. Circumcision for HIV Prevention

Bärnighausen, T., Bloom, D., and Humair, S. Proceedings of the National Academy of Sciences (December 2012), 109(52): 21271–21276.

This article reported on a model developed and applied in South Africa to compare the health effects and costs of scaling up treatment as prevention (TasP), expanded antiretroviral therapy (ART), and medical male circumcision (MMC) to prevent new HIV infections and avert deaths. The researchers defined TasP (initiating ART at CD4 cell count >350/μL) and ART (initiating ART at CD4 <350/μL) according to the World Health Organization definitions, and included optimistic assumptions about the programmatic effectiveness of TasP. The model showed that high ART coverage plus high MMC coverage provided roughly the same reduction in new HIV infections as TasP and cost some USD$5 billion less from 2009 to 2020. MMC was more cost-effective than ART in averting new infections, and similar in cost per death averted. TasP was significantly less cost-effective than either MMC or ART. In this model, which included recurrent costs but not start-up costs, the most cost-effective approach for reducing HIV mortality was to scale up MMC and ART together. The authors concluded that although TasP has been heralded as a “game changer,” continuing to scale up MMC and ART could have the same impact at significantly lower cost.

Laws Prohibiting Over-the-Counter Syringe Sales to Injection Drug Users: Relations to Population Density, HIV Prevalence, and HIV Incidence

Friedman, S. R., Perlis, T., & Des Jarlais, D. C. American Journal of Public Health (May 2000), 91(5): 791–3.

Some states in the U.S. have antidrug policies that permit the sale of syringes only to those with a prescription. Some researchers argue that such restrictions increase the extent to which people who inject drugs (PWID) share syringes and perhaps other drug paraphernalia. This cross-sectional analysis compared HIV prevalence and incidence among PWID in the 96 largest metropolitan areas in the U.S., based on whether syringes were available over the counter (OTC). The average HIV prevalence among PWID in areas allowing OTC sales of syringes was 7 percent, compared to 14 percent in those with anti-OTC laws, a statistically significant difference. The difference in estimated average HIV incidence among PWID was even greater: 61 percent in anti-OTC areas versus 17 percent in the other areas. Furthermore, there was no difference in the percentage of PWID in each area, indicating that anti-OTC policies may have no effect on drug use. While these results may have be due to other factors, this study supported the hypothesis that an association exists between anti-OTC policies and increased HIV prevalence.

Can HIV-1 Contaminated Syringes be Disinfected? Implications for Transmission among Injection Drug Users

Abdala, N., Gleghorn, A., Carney, J. M., et al. Journal of Acquired Immune Deficiency Syndromes (2001), 28(5), pp. 487–94.

In the absence of support for needle substitution programs in the United States, harm reduction programs encouraged people who inject drugs (PWID) to disinfect their syringes with bleach. Several population-based studies in the 1990s cast doubt on the effectiveness of bleach in decontaminating used syringes among PWID. This study recreated real-life situations among PWID in the United States, including common injection practices, using 2-mL syringes. Based on other studies indicating that PWID did not always follow the strict bleaching protocol, the study used multiple rinsing permutations (water only, diluted bleach, full-strength bleach; rinsing one, two, or three times; storing syringes for up to 48 days at room temperature) to assess whether these practices could remove HIV from a used syringe. While even one rinse of water could reduce the presence of HIV, increasing the number of rinses and adding bleach to the rinsing procedure furthered the decreases in amount of HIV recovered. The authors recommended encouraging needle rinsing, preferably with bleach, as part of harm reduction interventions.

Do Needle Syringe Programs Reduce HIV infection Among Injecting Drug Users: A Comprehensive Review of the International Evidence

Wodak, A., & Cooney, A. Substance Use and Misuse (February 2006), 41(6-7): 777–813.

Using commonly accepted criteria for evaluation of public health interventions, the authors reviewed evidence from 45 studies to find strong evidence that needle and syringe programs (NSPs) are effective, safe, and cost-effective. The evidence in favor of NSPs as an HIV prevention intervention is overwhelming, they said, but the availability of sterile needles and syringes from pharmacies is a common confounder in studies looking at NSP implementation and HIV prevention. Moreover, although the benefits of NSPs are proven, they are insufficient on their own to prevent HIV among people who inject drugs. The authors made recommendations for future action and also provided a useful glossary of terms.

A Review of the Efficacy and Effectiveness of Harm Reduction Strategies for Alcohol, Tobacco and Illicit Drugs

Ritter, A., and Cameron, J. Drug and Alcohol Review (November 2006), 25(6): 611–24.

This review of over 650 articles on harm reduction strategies found that most strategies concerned illicit drugs. The review found compelling evidence to show that needle substitution programs and outreach are useful and cost-effective, but findings to support noninjecting routes of administration, supervised injecting facilities, and naloxone distribution are only beginning to emerge. The existing evidence on brief interventions, HIV testing, and education is not conclusive, the authors said. The review also evaluated harm reduction as a policy approach and found that despite difficulties interpreting data, the evidence supports harm reduction as a driver of policy, rather than simply the basis of individual interventions.


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