An important update to official CDC guidelines:
For HIV-positive MSM, taking ART regularly greatly reduces the risk of HIV transmission to a negative partner. For persons who achieve and maintain viral suppression, there is effectively no risk of transmitting HIV to their HIV-negative sexual partner.
This translates to an effectiveness estimate of 100% for taking ART regularly as prescribed and achieving and maintaining viral suppression. Effectiveness is lower, and there is a risk of transmitting HIV, when persons do not take ART as prescribed or stop taking ART, if viral suppression is not achieved, or if viral suppression is not maintained.
When taking PrEP daily or consistently (at least 4 times per week), the risk of acquiring HIV is reduced by about 99% among MSM. While daily use is recommended in the U.S., taking PrEP consistently (at least 4 times per week) appears to provide similar levels of protection among MSM. The effectiveness of oral PrEP is highly dependent on PrEP adherence.
When taking oral PrEP daily or consistently, HIV acquisition is extremely rare and has not been observed in any of the studies described below. In clinical practice, a few cases of new HIV infections have been confirmed while HIV-negative individuals were on PrEP with verified adherence.
Activist Peter Staley reacts:
Huge victory, folks. The CDC finally updated its page on risk levels of getting HIV, using stats that reflect what the science and the real world are telling us. Having an undetectable viral load (U=U) is considered 100% protective (untransmittable).
PrEP use among gay & bi men is 99% effective. These changes finally remove the confusion between most of our prevention ad campaigns and the CDC’s website (where they had been using older, more conservative estimates).