The fact that people infected with HIV who are virally suppressed cannot sexually transmit the virus to others is now accepted in the HIV/Aids community as a result of accumulating evidence since the early 2000s.
In early 2016, the Undetectable=Untransmissable (U=U) slogan was launched by the Prevention Access Campaign to promote the finding. The campaign has been rapidly gathering momentum, having been endorsed by more than 400 organisations from 60 different countries since its launch.
Last month, the US Centres for Disease Control and Prevention (CDC) joined the movement by endorsing the science in a letter released on National Gay Men's HIV/AIDS Awareness Day.
[link url="http://www.thelancet.com/journals/lanhiv/article/PIIS2352-3018(17)30183-2/abstract"]The Lancet HIV material[/link]
[link url="http://www.thelancet.com/journals/lanhiv/article/PIIS2352-3018(17)30183-2/fulltext"]The Lancet HIV article[/link]