A person is undetectable if they are HIV-positive and take their medications regularly so the virus is suppressed in their body. In fact, it’s so suppressed that tests would not even detect the virus in a sample of their blood.
Science has confirmed that when a person living with HIV is undetectable, they’re not only healthier, they also cannot pass HIV to anyone else. Or, Undetectable = Untransmittable (U=U).
A person will stay undetectable as long as they take their medication as prescribed.
Being undetectable doesn’t mean a person is cured of HIV, but it is an effective HIV prevention option.
Some people living with HIV do not have undetectable viral loads. They can also prevent transmission by using condoms with their partner, or their partner using PrEP.