The following passage from the CDC site regarding U=U applies to both heterosexual men and women and to MSM:
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 [antiretroviral therapy] 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.
Regarding PrEP and MSM, the CDC writes:
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.
Regarding PrEP and heterosexual men and women, the CDC writes:
There is evidence for the effectiveness of PrEP when used recently (based on detecting TFV [tenofovir disoproxil fumarate, one of the drugs in Truvada] in plasma), which is estimated to be 88–90% as described below. There is no effectiveness estimate of PrEP when taken daily or consistently among heterosexuals; however, it is likely to be greater than the estimates corresponding to recent use and similar to what has been observed for MSM. The effectiveness of oral daily PrEP is highly dependent on PrEP adherence, with maximum effectiveness when taking PrEP daily and lower effectiveness when not taken consistently.
Regarding PrEP and people who inject drugs (PWID), the CDC writes:
PWID face HIV risks from both injecting and sex behaviors. Studies on the effectiveness of PrEP when taken daily among PWID are limited. However, when taking PrEP consistently, the risk of acquiring HIV is reduced by an estimated 74–84% among PWID. These estimates are based on tenofovir alone and among a subset of PWID taking PrEP consistently, as verified by directly observed therapy or daily diary plus monthly pill count. The effectiveness of two-drug oral therapy has not been assessed among PWID but may be higher. The effectiveness of oral daily PrEP is highly dependent on PrEP adherence, with maximum effectiveness when taking PrEP daily and lower effectiveness when missing doses.
Content Source: https://www.poz.com/article/uu-prep-work-cdc-updates-answers#lid=d5ab18bd98.6d2e545b42
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