Pre-Exposure Prophylaxis (PrEP)
What is PrEP?PrEP is short for Pre-Exposure Prophylaxis. It is a new HIV prevention method in which people who do not have HIV take a daily pill to reduce their risk of becoming infected. When used consistently, 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 PrEP is safe and effective in reducing HIV infection among injection drug users, but those results are not yet available.
Based on studies to date, in July 2012 the U.S. Food and Drug Administration approved the combination medication tenofovir disoproxil fumarate plus emtricitabine (TDF/FTC) for use as PrEP among sexually active adults at risk for HIV infection.
For some individuals at high risk for HIV infection, PrEP may represent a much-needed additional prevention method, but it will not be right for everyone and is not intended to be used in isolation, but rather in combination with other methods to reduce the risk of getting HIV infection. If it is delivered effectively and targeted to those at highest risk, PrEP may play a role in helping to reduce the significant continuing toll of new HIV infections in the United States. CDC is currently working with partners to ensure safe and effective PrEP use and begin to address key questions about acceptability, access, adherence, behavioral risks, and patient outcomes in community settings.
PrEP RESEARCHIn November 2010, the National Institutes of Health (NIH) announced the results of the iPrEx clinical trial, a large, multi-country research study examining PrEP among MSM. The study found that daily oral use of TDF/FTC provided an average of 44% additional protection to MSM who also received a comprehensive package of prevention services that included monthly HIV testing, condom provision, and management of other sexually transmitted infections. The level of protection varied widely depending on how consistently participants used PrEP, with significantly greater levels of protection among those who adhered well to the daily regimen. Among MSM with detectable levels of the medication in their blood, the risk of HIV acquisition was reduced by more than 90 percent.
In July 2011, a CDC study called TDF2, along with a separate trial by the University of Washington (Partners PrEP), 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:
- TDF2, conducted in partnership with the Botswana Ministry of Health, found that once-daily TDF/FTC reduced the risk of acquiring HIV infection by 62 percent overall in the study population of uninfected heterosexual men and women. Blood level data showed that participants who became infected had far less drug in their blood, compared with matched participants who remained uninfected suggesting that medication adherence is associated with the efficacy of PrEP in preventing HIV infection.
- Partners PrEP found that two separate antiretroviral regimens – tenofovir alone and TDF/FTC in combination – when provided to uninfected persons whose partners have HIV infection (serodiscordant couples) significantly reduced HIV aquisition (by 62 percent and 73 percent, respectively). Participants in the tenofovir- only group with detectable levels of the medication experienced an 86 percent reduction in risk for HIV infection; in the TDF/FTC group, the presence of medication in the blood was associated with a 90 percent reduction in risk. CDC co-managed two of the nine sites for this study.
Additional CDC Publications
- Press Release: CDC Trial and Another Major Study Find PrEP Can Reduce Risk of HIV Infection among Heterosexuals
- Media Statement: CDC issues interim guidance to health care providers on the use of pre-exposure prophylaxis (PrEP) as an HIV prevention strategy among men who have sex with men
- CDC Interim PrEP Guidance Graphic
- MMWR: Interim Guidance: Pre-Exposure Prophylaxis for the Prevention of HIV Infection in Men Who Have Sex with Men
- Media Statement: CDC statement on the results of the National Institutes of Health’s iPrEx trial, examining Pre-Exposure Prophylaxis (PrEP) for HIV prevention among men who have sex with men
- Media Summary: Preliminary Results from First Safety Study of Daily Tenofovir for HIV Prevention Among MSM Find No Significant Concerns
- Related Materials: Fact Sheet: CDC U.S. Extended PrEP Safety Trial Quick Facts on Trial Design