A man has become the first person reported to have been infected by HIV despite adhering to the daily regimen of Truvada (tenofovir/emtricitabine) as pre-exposure prophylaxis (PrEP).
PrEP can be 99% effective in stopping the transmission of HIV, according to scientific studies; though this case of seroconversion shows that the drug is indeed not 100% effective.
As reported by POZ, the PrEP-using individual contracted a multi-drug resistant strain of HIV, so that scientists concluded that “it is indeed possible for individuals who are adherent to PrEP to contract HIV when they are exposed to a virus that is resistant to both drugs included in Truvada.”
An earlier study noted that while PrEP may be effective, many do not practice safer sex when in use of the medicine. Particularly, study participants were less likely to use condoms and many of them contracted at least one STI over the 2.5 year duration of the study. Thirty percent of the men in the same study contracted an STI within six months of starting PrEP, and another 50 percent contracted one within a year of starting the medication.
The individual involved – a 43-year-old man who has sex with men – adhered to PrEP over the long-term. However, after 24 months on Truvada, he tested positive for HIV. Initial tests indicated that he was acutely/very recently infected. He tested positive for the p24 antigen, which appears within about three weeks of HIV infection and disappears a few weeks afterward; and at that time he tested negative for HIV antibodies, which typically appear two to eight weeks after infection.
Interviewed by POZ, Richard Harrigan, PhD, director of the lab program at the British Columbia Center for Excellence in HIV/AIDS in Vancouver, Canada, said: “I certainly don’t think that this is a situation which calls for panic. It is an example that demonstrates that PrEP can sometimes be ineffective in the face of drug resistant virus, in the same way that treatment itself can sometimes be ineffective in the face of drug resistant virus. This case demonstrates that while PrEP is beneficial, we can’t rely on it to be an infallible magic bullet.”
Since his diagnoses, the man in the case has successfully suppressed his viral load via alternate HIV medications [Tivicay (dolutegravir), Prezcobix (darunavir/cobicistat), and Edurant (rilpivirine)].