In November 2010, the National Institutes of Health (NIH) announced the results of the iPrEx trial, a large research study examining whether a pill containing drugs used to treat HIV can also help prevent HIV infection -- an approach called pre-exposure prophylaxis, or PrEP. These findings represent a major advance in HIV prevention research, providing the first evidence that PrEP, when combined with other prevention strategies, can reduce HIV risk among men who have sex with men (MSM) (see Key Findings box).
The iPrEx results have immediate implications for the U.S., because tenofovir-emtricitabine pills are already FDA-approved and available with a prescription for the treatment of HIV infection. As the agency responsible for protecting public health, CDC is taking steps to promote the safe and effective use of PrEP in the United States.
Efficacy: The trial found that a once-daily pill containing tenofovir plus emtricitabine (brand name Truvada®) provided an average of 44 percent protection to men who have sex with men and transgender women who have sex with men who also received comprehensive prevention services which included monthly HIV testing, condom provision, counseling, and management of other sexually transmitted infections.
Consistent use of PrEP: The level of protection varied widely depending on how consistently participants used PrEP. Among those whose data (based on self-reports, bottles dispensed, and pill counts) indicates use on 90 percent or more days, HIV risk was reduced by 73 percent, while among those whose adherence by the same measure was less than 90 percent, HIV risk was reduced by only 21 percent.
Risk behavior: Risk behavior among participants declined overall during the trial both in terms of decreases in the number of sexual partners and increases in condom use, likely as a result of the intensive risk reduction counseling provided as part of the trial.
HIV among MSM in the U.S.: The HIV epidemic among MSM in the U.S. is severe, and additional risk reduction strategies for this population are urgently needed. MSM represent more than half of new HIV infections and nearly half of all people living with HIV in the U.S., and the rate of new HIV diagnoses among MSM is more than 44 times that of other men. Moreover, data suggest that HIV infections have been steadily increasing in this group since the mid-1990s.
Implications of findings for other PrEP trials: While we don't yet know if PrEP will work for preventing HIV transmission in other populations, these findings among MSM give us hope that this approach might also prove effective among heterosexuals at high-risk for HIV and injection drug users. CDC, NIH, and other institutions are conducting trials around the world to determine the safety and effectiveness of PrEP for these populations; those results are expected within the next few years. The iPrEx results may also be the first step toward other effective and potentially more feasible options for PrEP, as other regimens and dosing strategies are also being evaluated.
CDC next steps: CDC is pursuing two primary goals in the wake of the iPrEx trial findings: developing guidance on the safe and effective use of PrEP and determining how to most effectively use PrEP in combination with other prevention strategies to reduce new infections in the U.S. The following pages describe these goals in greater detail, and discuss key remaining questions about PrEP as an HIV prevention tool.
CDC is currently leading national efforts to develop formal U.S. Public Health Service guidelines on PrEP among MSM.
However, given the commercial availability of Truvada® and the possibility of immediate interest in PrEP among some high risk gay and bisexual men and their physicians, CDC has already provided initial cautions on PrEP use (see below), as well as interim guidance for physicians electing to provide PrEP for HIV prevention among high risk MSM (see box).
For MSM at high risk for HIV infection, PrEP may represent a much-needed additional prevention tool. However, PrEP should be used only in combination with other HIV prevention strategies, requires strict adherence, and is an intensive approach that won't be right for everyone.
Anyone considering using PrEP should know:
CDC recently published interim guidance for physicians to help inform clinical practice as formal U.S. Public Health Service guidelines are being developed.
|CDC Interim Guidance on HIV Pre-Exposure Prophylaxis for Men Who Have Sex With Men|
Before Initiating PrEP
Other recommended actions
Beginning PrEP Medication Regimen
Follow-Up While PrEP Medication Is Being Taken
On Discontinuing PrEP (at Patient Request, for Safety Concerns, or If HIV Infection Is Acquired)
Abbreviations: STI = sexually transmitted infection; TDF = tenofovir disoproxil fumarate; FTC = emtricitabine.
Source: "Interim Guidance: Pre-exposure prophylaxis for the prevention of HIV infection in men who have sex with men," CDC Morbidity and Mortality Weekly Report, January 28, 2011.
CDC is the lead federal agency in developing U.S. Public Health Service guidelines, in collaboration with other federal health agencies. The guidelines will be based on a full review of trial data and other research, and will incorporate input from providers, HIV prevention partners, and affected communities. The guidelines will help ensure both physicians and MSM have accurate information to guide decisions about the use of PrEP.
Topics to be addressed in the guidelines will include:
The iPrEx trial findings offer a new tool to help combat HIV among MSM, one of the hardest hit populations in the U.S. and many areas of the world.
We will have to carefully consider how to most effectively use this tool in combination with other prevention strategies to reduce the continuing toll of HIV and AIDS. There are a significant number of HIV-positive individuals in the U.S. and around the world who do not have access to antiretroviral drugs to treat their infection, and we know that treatment not only benefits infected individuals, but can also reduce transmission of HIV to others. But, we also know that treatment alone will not end the epidemic. With 2.7 million people becoming infected annually worldwide, including approximately 56,000 in the U.S., we must capitalize on every available prevention tool.
Ultimately, the impact of PrEP on the U.S. HIV epidemic will depend on difficult decisions and many things that remain unknown, including the feasibility, cost, and impact of this strategy in real-world settings.
Available data suggest that PrEP, used strategically and effectively among MSM, could have a positive impact on the U.S. epidemic and be cost-effective, but only if certain conditions are met, including:
CDC will be implementing a range of activities to promote the effective and strategic use of PrEP in the U.S. In addition to developing public health guidelines, CDC will:
CDC has also identified other activities that could help address remaining research questions and is currently exploring all avenues to identify resources to support them. Key among these is the need for demonstration projects in clinics serving MSM to assess feasibility, acceptability, and the impact of PrEP in real-world settings. It will also be critical for public and private sector partners to begin to collectively address the significant financial barriers that may place PrEP out of reach for many MSM at highest risk for HIV infection.
Given the urgency of addressing the HIV epidemic among gay and bisexual men in this nation, CDC is working to maximize the impact of this important new intervention in combination with all available HIV prevention strategies.
For more information on PrEP and HIV prevention, please visit www.cdc.gov/hiv/prep.