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CDC Statement on Results of iPrEx Trial Examining Pre-Exposure Prophylaxis (PrEP) for HIV Prevention Among Men Who Have Sex With Men

November 23, 2010


Today the National Institutes of Health (NIH) announced results of the international iPrEx trial examining whether drugs used to treat HIV can also help prevent HIV infection.  This approach is called pre-exposure prophylaxis, or PrEP; trial findings showed that a once-daily pill containing tenofovir plus emtricitabine (brand name Truvada?) was safe and provided an average of 44 percent (95% CI 15 to 63%) additional protection against HIV infection to men who have sex with men (MSM) and transgendered women who have sex with men, who also received a comprehensive package of prevention services. These services included use of condoms, monthly HIV testing, counseling, and management of other sexually transmitted infections.  The level of protection shown varied widely depending on how consistently participants used PrEP.  Among those whose data (based on self-reports, bottles dispensed, and pill counts) indicate use on 90 percent or more days, HIV risk was reduced by roughly 73 percent (95% CI 41 to 88%), while among those whose adherence by the same measure was less than 90 percent, HIV risk was reduced by only about 21 percent (95% CI, from a 52% reduction to a 31% increase).

Statement From Dr. Kevin Fenton, M.D., Director, CDC National Center for HIV/AIDS, Viral Hepatitis, STD & TB Prevention

"These results represent a major advance in HIV prevention research. For the first time, we have evidence that a daily pill used to treat HIV is partially effective for preventing HIV among gay and bisexual men at high risk for infection, when combined with other prevention strategies. Given the heavy burden of HIV among gay and bisexual men, a new tool with potential additive benefit is exciting and welcome news.

"These findings add to a growing body of knowledge regarding the use of treatment drugs for HIV prevention and provide hope that PrEP may also prove effective for other hard hit groups of people around the world.  CDC, NIH, and other institutions are conducting ongoing trials to determine the safety and effectiveness of PrEP for injection drug users and heterosexuals at high risk, and 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 are also being evaluated.  Given the continued severity of the HIV epidemic, safe and effective new approaches are urgently needed for all populations at risk.

"Today's results are exciting, but it is not time for anyone to stop using condoms or stop following proven prevention methods. Today's trial results show that PrEP is partially effective and does not protect against other sexually transmitted infections such as syphilis, gonorrhea, and chlamydia.  It cannot be seen as the first line of defense against HIV.  PrEP requires careful adherence, and is an intensive approach that won't be right for everyone.  As this study shows, taking a daily pill is not as simple as it sounds.  In this trial, PrEP was also only shown to be effective among gay and bisexual men and when provided with condoms and other prevention tools.

"The impact of PrEP in the United States will depend on how effectively we utilize it in combination with all available treatment and prevention strategies to reduce the human and economic toll of HIV. The hard work begins now, and many critical questions must be answered for people in the United States and around the world.  These include feasibility, cost, and impact in non-trial settings.  Success will also depend on whether we can identify ways to achieve the high levels of drug adherence needed for maximum protection and prevent increases in risky behavior that could offset the benefit of PrEP.  

"In the coming months, CDC, in collaboration with other federal health agencies and stakeholders, will be fully reviewing the data and developing detailed public health guidelines on the safe and effective use of PrEP.  We urge individuals to wait for those guidelines.  However, because the drug is currently approved in the United States for other uses and is commercially available in the United States with a prescription, we are issuing a number of immediate cautions to physicians and gay and bisexual men."

Immediate CDC Cautions for MSM Considering PrEP as an HIV Prevention Strategy

To ensure men who have sex with men (MSM) and their healthcare providers have accurate information on PrEP, CDC will publish interim guidance for healthcare providers in the coming weeks in the Morbidity and Mortality Weekly Report, followed by formal U.S. Public Health Service guidelines.

While those guidelines are being developed, CDC provides the following immediate cautions:

  • PrEP has only been shown to reduce HIV infection among men who have sex with men. There are no data regarding its benefit among heterosexuals or injection drug users.
  • The only drug evaluated in this study was Truvada and therefore, it is the only medication, at this time, that should be considered in the context of PrEP.  Providers and patients should also be aware that HIV prevention is not currently a labeled indication of the use of this medication.
  • PrEP should only be used among individuals who have been confirmed to be HIV-negative.  Initial and regular HIV testing are critical for anyone considering using PrEP.  All individuals considering PrEP must also be evaluated for other health conditions that may impact PrEP use.
  • PrEP should never be seen as the first line of defense against HIV.  It has only been found to be partially effective when provided in combination with regular HIV testing, condoms, and other proven prevention methods. PrEP does not protect against other sexually transmitted infections.  Men who have sex with men should continue to:

    • Use condoms consistently and correctly
    • Get tested to know their HIV status and that of their partner(s)
    • Get tested -- and treated if needed -- for other sexually transmitted infections that can facilitate HIV transmission, such as syphilis and gonorrhea
    • Get information and support to reduce drug use and risky sexual behavior
    • Reduce their number of sexual partners
  • Taking PrEP daily is critical.  This study found that PrEP provided a high level of protection only to those who took the pills regularly; protection was very low among those who did not rigorously adhere to the daily regimen.
  • PrEP must be obtained from and used in close collaboration with health care providers to ensure regular HIV testing, risk reduction and adherence counseling, and careful safety monitoring.

CDC will be working with its partners on many additional steps to promote safe and appropriate use of PrEP and determine how to maximize the impact of PrEP in the United States. For the international health community, WHO and UNAIDS will lead international efforts to develop guidance on implementation.  For more information on next steps in the United States, see Fact Sheet: Pre-Exposure Prophylaxis (PrEP) for HIV Prevention.

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This article was provided by U.S. Centers for Disease Control and Prevention. Visit the CDC's website to find out more about their activities, publications and services.
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