Antiretroviral medications used to treat HIV can also be used to prevent it:
Administering antiretroviral medications to HIV-infected pregnant women and their newborns significantly reduces the risk of HIV transmission to infants during pregnancy, labor and delivery, and breastfeeding.2, 3
Treating people with HIV lowers the amount of virus in their body and can dramatically reduce their risk of transmitting HIV to others, underscoring the importance of HIV testing and access to medical care and treatment. In fact, a landmark clinical trial in 2011 showed that people with HIV who began taking anti-HIV medications early (before their immune systems were significantly weakened) experienced a 96 percent reduction in their risk of transmitting HIV to their sexual partners.4
When started promptly after exposure to HIV, antiretroviral medications can reduce the risk of infection.5, 6 For example, a nurse accidentally stuck with a needle that may have been in contact with HIV-infected blood can reduce the risk of infection by completing a four-week course of medications. Partially thanks to PEP, there have been no confirmed cases of occupational HIV transmission to health care workers in the United States since 1999. Non-occupational PEP can also reduce risk of infection if started promptly after exposure to HIV through sexual risk behavior or injection drug use.
With PrEP, HIV-negative individuals take a daily dose of antiretroviral medication to lower their chances of acquiring HIV. Daily PrEP using the drug TDF/FTC has been shown to be safe and effective in reducing the risk of HIV infection among gay and bisexual men and heterosexual men and women when consistently used. Studies have shown that the level of protection is strongly related to the level of adherence to the daily regimen.7, 8, 9 One additional trial of the effectiveness of daily PrEP among heterosexual women is ongoing and may provide additional insight into any factors that may make PrEP more or less effective in that population, and CDC is also working to complete a trial of the effectiveness of daily PrEP in reducing HIV transmission among injection drug users.
In time, PrEP may play an important role in HIV prevention, and work is ongoing to determine how to successfully implement PrEP programs in an efficient and cost-effective manner. Demonstration projects and open-label studies now underway will begin to address some of the critical real-world questions about how to most effectively use PrEP in combination with other proven prevention methods.
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