Don’t be fooled: PrEP failures imply nothing about U = U

published on February 22, 2017 by Bob Leahy, in Positive Lite

Bob Leahy and the myth that because PrEP very occasionally has failed, the reliability of a sustained undetectable viral load as an effective prevention strategy for people living with HIV needs questioning

The HIV world was jumping, if not jittery, last week, with a third case of HIV pre-exposure prophylaxis (PrEP) failure reported, this time, at CROI 2017. Notable was that it did not involve drug–resistance, the cause of the previous two widely reported PrEP failures, including one occurring in Toronto. In fact the reason for PrEP failure in this latest case, a 50-year old gay man from the Netherlands, a heavy drug user who was extremely sexually active - and there may be some clues there - remains a question for scientific debate.

Want to know more? The case is particularly complicated. For a full review of the circumstances go here .

Inevitably the suggestion has been raised on Facebook and elsewhere that PrEP failures point to the unreliability of undetectable viral load as a prevention method. In fact I have heard colleagues who work is gay men’s sexual health tell me that PrEP failures are why you cannot say Undetectable = Untransmittable. a message which even the International AIDS Society and many others, including CATIE, support.

Frankly that’s a fallacious argument that needs to be shot down.

Simply put PrEP and treatment as prevention (TasP) are two entirely different animals. Comparisons between the differing results of the two make no sense.

One more time . . PrEP is a regime for people who are HIV-negative. Nobody has ever said PrEP is 100% safe – in fact Gilead, the manufacturers of Truvada, recommend it be used in combination with condom use. “Nevertheless PrEP appears to be nearly 100% effective if taken consistently so that there are high drug levels in the body at the time of exposure to HIV” says aidsmap.

In contrast, the use of ART to maintain an undetectable viral load in people living with HIV works to reduce levels of virus in the blood to such low levels that the virus cannot be transmitted sexually. There have been no transmissions in carefully monitored studies involving individuals engaged in condomless sex with discordant partners.

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BC Centre for Excellence in HIV/AIDS

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Don’t be fooled: PrEP failures imply nothing about U = U

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