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Breakthrough Infection of Man Taking PrEP

April 5, 2016

David Knox, M.D. reported at CROI 2016 in Boston on the first well-described case of a gay man taking daily Truvada for PrEP becoming infected with HIV despite high adherence. It should be noted that this is the first documented case in the tens of thousands who've taken PrEP in the United States since Truvada's approval for this indication in July 2016, and that there were unique circumstances that could have influenced this transmission of HIV.

The man, who shared his story in POZ on March 3, 2016 had been taking Truvada since the spring of 2013. He reported high adherence, and Knox reported that blood tests indicated that the man had high levels of Truvada present at the time of the HIV transmission. The virus with which the man became infected was moderately to highly resistant to three classes of drugs, including both of the drugs contained in Truvada. Sensitivity to tenofovir was modestly reduced, but sensitivity to emtricitabine was significantly reduced, leaving him particularly vulnerable to infection.

Unfortunately, the virus with which the man became infected was also substantially resistant to the integrase inhibitor class and to non-nucleoside reverse transcriptase inhibitors. Fortunately, his doctors have been able to get his virus suppressed on an unusual combination of HIV drugs, though the breadth and degree of resistance does mean that the man has a vastly reduced number of drugs left to which he could switch if the combination he's currently on stops working.

Project Inform has published a list of considerations (link here to the other piece) for what this case means practically for those seeking or taking Truvada for PrEP, and those who serve or treat them medically. In short, however, we should not be surprised that a medication as potent as Truvada is (at least for protection from anal sex) does have vulnerabilities and is not full proof.


David C Knox, et al. "HIV-1 Infection With Multiclass Resistance Despite Preexposure Prophylaxis (PrEP)". CROI 2016, Boston. Abstract 169aLB.

This article was provided by Project Inform. It is a part of the publication The 23rd Conference on Retroviruses and Opportunistic Infections. Visit Project Inform's website to find out more about their activities, publications and services.

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