This article considers merits and drawbacks of "undetectable = untransmissible" (U = U) messaging in the global HIV response. First, viral suppression might be achieved with effective treatment, but not everyone living with HIV has access to such intervention and care. Second, although U = U can help individuals living with HIV, this messaging might stigmatize those for whom interventions have not achieved viral suppression. Third, although biomedical advances have attempted to address infectiousness, syndemic drivers that predispose individuals to HIV acquisition are not well accounted for by U = U messaging.To claim one AMA PRA Category 1 Credit TM for the CME activity associated with this article, you must do the following: (1) read this article in its entirety, (2) answer at least 80 percent of the quiz questions correctly, and (3) complete an evaluation. The quiz, evaluation, and form for claiming AMA PRA Category 1 Credit TM are available through the AMA Ed Hub TM .