摘要：Orally administered preexposure prophylaxis is an innovative and controversial HIV prevention strategy involving the regular use of antiretroviral medications by uninfected individuals. Antiretroviral medications protect against potential HIV infection by reducing susceptibility to the virus. Recent clinical trial results indicate that preexposure prophylaxis can be safe and efficacious for men who have sexual intercourse with men, yet there remain policy considerations surrounding costs, opportunity costs, and ethical issues that must be addressed before broad implementation in the United States. A NUMBER OF BIOMEDICAL interventions now becoming available will move HIV prevention well beyond admonitions to adhere to ABC (abstain, be faithful, and use condoms). Rather than relying exclusively on behavior change, these novel prevention strategies combine medical with behavioral approaches. Preexposure prophylaxis (PrEP), postexposure prophylaxis (PEP), and test and treat or testing with linkage to care (TNT/TLC+) have enormous potential to leverage the power of antiretroviral medications (ARVs) to limit the spread of HIV by reducing an individual's susceptibility to HIV or by reducing community viral load. As we move into the post-ABC world, weighing policy concerns of cost, opportunity costs, and ethical issues of these new biomedical strategies is important. Orally administered PrEP is an innovative and controversial HIV prevention strategy that involves the regular use of existing ARVs to protect uninfected individuals against potential HIV infection. Using antiretroviral agents to decrease the risk of HIV transmission has already been successful in reducing transmission from HIV-positive mothers to their infants, curbing HIV infection through breastfeeding of uninfected infants, and protecting against occupational exposure. 1 The Centers for Disease Control and Prevention (CDC) and the National Institutes of Health (NIH) are supporting randomized clinical trials of PrEP in 13 countries (including the United States) that involve more than 20 000 participants. 2 Results on PrEP use by men who have sexual intercourse with men (MSM) from the Pre-Exposure Prophylaxis Trial Initiative (iPrEx) were released in late 2010. 3 The study results generated a great deal of enthusiasm and optimism because they indicated that HIV incidence was 44% lower in MSM receiving PrEP compared with controls. Participants who took the medication on 90% or more of days had a 79% decrease in HIV incidence. 3 These randomized clinical trial results suggest that PrEP is a promising strategy, but we must temper this promise with a healthy dose of caution. PrEP is an intensive intervention for which cost, feasibility, and behavioral considerations may be as important as clinical efficacy. Thus, we must continue to examine the viability of PrEP as an HIV-prevention strategy, especially considering the development of competing biomedical prevention modalities. The iPrEx results provide strong clinical evidence that PrEP can reduce seroconversion rates in experimental participants. However, the trials have not been designed to address crucial policy issues involved in full-scale implementation. Attendees at the Preparing for PrEP Conference in 2009 rightly called for “proof of deliverability” before PrEP implementation. 4 We would like to add that proof of desirability is equally important and should be considered. Before launching full PrEP implementation, a window of opportunity exists to consider the pragmatic policy issues PrEP presents within the current political and financial context. The interpretation of the PrEP randomized clinical trial results and the desirability of PrEP promotion must be considered from the perspective of costs, associated opportunity costs, and ethical dilemmas created.
