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HIV Prevention Knowledge Base

A Collection of Research and Tools to Help You Find What Works in Prevention

Biomedical Interventions: Post-exposure Prophylaxis (PEP)

Link to important additional materials and websites

Antiretroviral Agents Used by HIV-Uninfected Persons for Prevention: Pre- and Postexposure Prophylaxis

Grant, R. M. Clinical Infectious Diseases (2010), Vol. 50 Suppl. 3, pp. S96–101.

The author reviews the range of biomedical prevention therapies from prevention of mother-to-child transmission to pre-exposure prophylaxis (PrEP) and PEP. The author also discusses issues that challenge research on new prophylactic approaches and individual and societal barriers that affect provision and use. PEP is not commonly offered where resources are scarce because questions about treatment efficacy and regimen safety prevail. The author also considers issues that have been raised with respect to PrEP (a daily oral dose of a single ARV or in combination) and microbial (ARV in gel form) prevention approaches for high-risk populations. A concern raised is that prevention options like these confer safety from HIV and may lead individuals to believe that they can engage in risky sexual behavior. Clinical trials currently underway will provide answers to some of these concerns and will help inform decisions by implementers and policymakers in determining what programs are offered in resource-poor locales. The author cautions that community acceptance and support for biomedical approaches like these are critical to adherence and successful outcomes.

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Narrative Review: Antiretroviral Therapy to Prevent the Sexual Transmission of HIV-1

Cohen, M. S., Gay, C., Kashuba, A. D. M., et al. Annals of Internal Medicine (2007), Vol. 146 No. 8, pp. 591–601.

This summary focuses on the findings of prevention studies for PrEP and PEP within the larger literature review covered by the article. The rationale for PEP is based on a series of studies conducted with rhesus and macaque monkeys that provide the critical parameters of treatment—namely, beginning ARVs not later than 72 hours after exposure and continuing with the regimen for 28 days. The limitations of animal studies for PEP reflect shortcomings of studies conducted with humans. Rigorous trials have not been carried out because they require very large samples and are prohibitively expensive or face ethical dilemmas. Therefore, studies use small samples and do not address long-term patient outcomes. In fact, only one study with humans has proven that PEP is effective in preventing HIV. This was a retrospective case control study of medical accidents with sharps (n = 679). An 81 percent reduction in risk was registered when ZDV (or another ARV drug) was administered to workers who were exposed. Protocols and guidelines used worldwide are based on this research and the series of animal studies. The authors discuss a number of potentially harmful consequences if widespread use of ART for prevention is adopted, including increased high risk behaviors on the part of people who believe themselves to be safe, emergence of drug resistance strains, and provision of ARVs to those with low probability for HIV transmission.

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National HIV/AIDS Clinicians’ Consultation Center

University of California, San Francisco. (2010).

This U.S.-based center hosts a PEP hotline for providers seeking clinical guidance related to the treatment occupational exposure to HIV.

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