When a person is living with HIV and is on effective treatment, it lowers the level of HIV (the viral load) in the blood. When the levels are extremely low (below 200 copies/ml of blood measured) it is referred to as an undetectable viral load. This is also medically known as virally suppressed.
At this stage, HIV cannot be passed on sexually.
This scientific evidence was gathered from several studies. The studies included thousands of heterosexual and gay couples in which one partner had HIV and the other did not. Over the course of the studies, they found that there was not a single HIV transmission from an HIV-positive partner who had an undetectable viral load.
