The latest update: U=U actually Works!  Undetectable = Un-Transmittable. As of August 2018, according to the Centers of Disease Control and Prevention (CDC), trials have proven people with HIV who take HIV medicine as prescribed who achieve and keep an undetectable viral load have effectively no risk of transmitting HIV to their-negative sexual partners.  About 80% of people in HIV Care were viral suppressed at their last test.  About 2/3 of people in HIV care maintained viral suppression over a year.