Pre-Exposure Prophylaxis (PrEP)

What is PrEP?

PrEP is short for PreExposure Prophylaxis and may be part of comprehensive HIV prevention services in which HIV negative people who are at high risk, take antiretroviral medication daily to try to lower their chances of becoming infected with HIV if they are exposed to it. To date, PrEP has been shown to be effective in men who have sex with men (MSM) and heterosexual men and women. A CDC study is also underway to evaluate whether it is safe and effective in reducing HIV infection among injection drug users, but those results are not yet available.

Updates

Press Release: CDC Trial and Another Major Study Find PrEP Can Reduce Risk of HIV Infection among Heterosexuals Added on July 13, 2011
Fact Sheet: TDF2 Study of Pre-Exposure Prophylaxis (PrEP) Among Heterosexual Men and Women in Botswana: Key Facts Added on July 13, 2011
Dear Colleague Letter: FEM-PrEP Clinical Trial examining Pre-Exposure Prophylaxis (PrEP) for HIV prevention among heterosexual women Added on April 15, 2011

In November 2010, the National Institutes of Health (NIH) announced the results of the iPrEx clinical trial, a large, multi-country research study examining PrEP. The study found that daily oral use of tenofovir plus emtricitabine (TDF/FTC, brand name Truvada) provided an average of 44% additional protection to men who have sex with men (MSM) who also received a comprehensive package of prevention services that included monthly HIV testing, condom provision, and management of other sexually transmitted infections.

In July 2011, a new CDC study called the TDF2 study, along with a separate trial by the University of Washington, provided evidence that a daily oral dose of antiretroviral drugs used to treat HIV infection can reduce HIV acquisition among uninfected individuals exposed to the virus through heterosexual sex:

The TDF2 study, conducted in partnership with the Botswana Ministry of Health, found that once-daily TDF/FTC reduced the risk of acquiring HIV infection by roughly 63 percent overall in the study population of uninfected heterosexual men and women.

CDC researchers also conducted a separate analysis to better understand the level of effectiveness among trial participants believed to be taking their study medications. This analysis excludes any HIV infections that occurred more than 30 days after a participant's last reported drug dose, because those individuals could not have been taking study pills at the time of infection. These results indicate that TDF/FTC reduced the risk of HIV infection by 78 percent.
The University of Washington study, called Partners PrEP, found that two separate antiretroviral regimens – tenofovir and TDF/FTC – significantly reduced HIV transmission among serodiscordant couples, in which one partner is infected with HIV and the other is not (by 62 percent and 73 percent, respectively). CDC co-managed two of the nine sites for this study.

CDC is leading national efforts to develop formal Public Health Service guidelines for PrEP. Until those more detailed guidelines are available, CDC has already developed interim guidance for physicians electing to provide PrEP for HIV prevention among MSM (see graphic and other materials below). CDC will also be developing interim guidance for physicians on PrEP use among heterosexuals; CDC urges that physicians await CDC guidance before using PrEP for heterosexuals.

If providers have heterosexual patients for whom they believe the initiation of PrEP is urgent, CDC recommends following the cautions and procedures previously published for PrEP use in MSM. However, because pregnant and breastfeeding women were excluded from participation in PrEP trials, further evaluation of available data will be needed before any recommendations can be made regarding the use of PrEP for women during conception, pregnancy, or breastfeeding.