Benjamin Young, MD, PhD
Jun 14, 2013
It is well established that antiretroviral treatment (ART) can prevent HIV/AIDS-related morbidity and mortality in HIV-infected individuals. Published in 2011, the landmark HPTN 052 study confirmed that ART (and an undetectable plasma viral load) can virtually eliminate the risk for transmission of HIV to sexual partners.[1] These and other advances in our understanding of how the use of ART can work to prevent new HIV infection are changing the lexicon of HIV medicine.
The notion of treatment as prevention (TasP) is now firmly established in language of World Health Organization and US Department of Health and Human Services treatment guidelines as components of counseling and testing of serodiscordant couples. Indeed, expansion of access to treatment and earlier initiation of treatment can even be viewed not only as a strategy to reduce the burden of HIV disease, but also as a way to reduce new HIV infections in some resource-limited settings,[2] although much additional research and debate is needed to ascertain the feasibility and challenges of scaling up this approach worldwide at the level of communities or nations.
Giving medications to HIV-uninfected individuals to reduce risk for infection dates to the earliest days of ART, when postexposure prophylaxis strategies were introduced. Several recent reports, including the iPrEx study,[3] demonstrated the feasibility of preexposure prophylaxis (PrEP), or the use of ART to prevent HIV infection before exposure in at-risk individuals. Together, these data led to approval by the US Food and Drug Administration of oral tenofovir/emtricitabine for PrEP and the release of interim guidance on PrEP by the Centers for Disease Control and Prevention.[4]
However, enthusiasm for PrEP has been tempered by appreciation of the critical role of adherence to PrEP. Two large studies -- FEM-PrEP and VOICE -- were halted early because of lack of efficacy, at least in part driven by suboptimal adherence to medication.[5] Many other investigations continue into strategies to address these limitations, such as alternative dosing strategies and newer medications with long half-lives.
Appreciating the rapid pace of investigations into these issues, in 2012 the International Association of Providers of AIDS Care (IAPAC) convened an international summit in London to review the scientific literature and to bring together global thought leaders for the purpose of generating discussion and clarifying areas of consensus and controversy.
The Consensus Statement of the summit, published in the current issue of the Journal of the International Association of Providers of AIDS Care, summarizes of the state of the science from the perspective of a diverse panel of experts representing healthcare providers, researchers, policy-makers, pharmaceutical companies, governmental and nongovernmental agencies, and advocacy groups.[6]
The advisory committee concluded that the current evidence for TasP's effectiveness justifies ART use in persons who wish to start treatment early. However, the committee noted that additional research is needed to evaluate the effectiveness and cost-effectiveness of TasP, particularly at the national level, and that effective deployment of TasP requires efforts to scale up HIV testing and improving the cascade of engagement in HIV care.
In addition, the advisory committee acknowledged the considerable challenges for the implementation of successful PrEP programs, including financial constraints, the need to identify and reach at-risk populations, and the importance of training a cadre of healthcare providers in this new discipline. Nevertheless, the committee agreed that the current evidence on the effectiveness and safety of daily oral PrEP supports its use in high-risk groups. The committee also recommended that PrEP be part of a comprehensive risk-reduction package and that safety monitoring and adherence counseling are required.
In short, antiretroviral treatment is prevention. For persons already infected with HIV, ART prevents disease progression and death; for those recently exposed to HIV and for those at risk for HIV infection, postexposure prophylaxis and PrEP can prevent the establishment of infection. At its best, ART can reduce the burden of the HIV/AIDS epidemic and perhaps portend the beginning of an AIDS-free generation. There will be tremendous additional challenges in finding the political will to accomplish this goal and in defining an optimal way forward.
I look forward to seeing how much further the community has traveled down this pathway when we reconvene at the second International Summit on Controlling the HIV Epidemic with Antiretrovirals, in London, in September 2013.
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