HIV Treatment as Prevention
People who are living with HIV should take medicine to treat HIV as soon as possible. HIV medicine is called anti-retroviral therapy, or ART. If taken as directed, HIV medicine reduces the amount of HIV (viral load) in the body to a very low level, which keeps the immune system working and prevents illness. This is called viral suppression—defined as having less than 200 copies/ml of blood. HIV medicine can even make the viral load so low that a test can’t detect it. This is called an undetectable viral load.*
Getting and keeping an undetectable viral load is the best thing people living with HIV can do to stay healthy. Another benefit of reducing the amount of virus in the body is that it helps prevent transmission to others through sex or needle sharing, and from mother to child during pregnancy, birth, and breastfeeding. This is sometimes referred to as “treatment as prevention.” There is strong evidence about treatment as prevention for some of the ways HIV can be transmitted, and more research is needed for other ways.
People living with HIV who take HIV medicine as directed and get and keep an undetectable viral load have effectively no risk of transmitting HIV to their HIV-negative sexual partners.
Transmission from pregnancy, labor, and delivery
If a woman living with HIV can take HIV medicine as directed throughout pregnancy, labor, and delivery and give HIV medicine to her baby for 4-6 weeks after delivery, the risk of transmitting HIV can be 1% or less.
Transmission from sharing needles or other injection drug use equipment
We don’t know whether getting and keeping an undetectable viral load prevents HIV transmission through sharing needles or other injection drug equipment. While we do not yet know if or how much being undetectable prevents some ways that HIV is transmitted, it is reasonable to assume that being on treatment and getting undetectable provides some risk reduction.
Transmission from breastfeeding
We don’t know if a woman living with HIV who has an undetectable viral load can transmit HIV to her baby through breastfeeding. While we do not yet know if or how much being undetectable prevents some ways that HIV is transmitted, it is reasonable to assume that being on treatment and getting undetectable provides some risk reduction.
* From this point forward, undetectable will refer to either viral suppression or an undetectable viral load.
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- Page last reviewed: October 17, 2017
- Page last updated: October 17, 2017
- Content source: Division of HIV/AIDS Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention