“Undetectable Equals Untransmittable,” or U=U

This means that people living with HIV who achieve and maintain an undetectable viral load — the amount of virus in their blood — by taking antiretroviral therapy (ART) as prescribed do not sexually transmit HIV to others.

The U.S. Centers for Disease Control and Prevention estimates this strategy is 100% effective against the sexual transmission of HIV.

This public health message has the power to reduce stigma, protect the health of people living with HIV and prevent sexual transmission of HIV to others.All published studies point to undetectable viral load as being the most effective method to date of preventing sexual HIV transmission.

The efficacy of treatment as prevention was first verified on a large scale by the NIH-funded HPTN 052 clinical trial, which showed that no linked HIV transmissions occurred among sero-different heterosexual couples when the partner living with HIV had a durably suppressed viral load.

Subsequently, the PARTNER 1 and 2 and Opposites Attract studies confirmed these findings and extended them to male-male couples. As described by authors of the current study, the independent non-profit organization Prevention Access Campaign launched the U=U slogan in 2016 to promote awareness of these scientific findings.

Importantly, U=U refers only to the prevention of sexually transmitted HIV; condoms are still needed to prevent the transmission of other sexually transmitted infections.