Towleroad is reporting that a gay man has tested positive for HIV even though he has been adhering to the prescribed dosage of the drug PrEP (preexposure prophylaxis).
According to the article the unnamed patient was taking Truvada for PrEP during seroconversion, however his strain of HIV was resistant to the regimen. In particular, the drugs tenofovir and emtricitabine which comprise Truvada.
POZ Magazine reports:
Researchers have for the first time documented a case of an individual contracting HIV, a multi-drug resistant strain, while apparently adhering well to the daily regimen of Truvada (tenofovir/emtricitabine) as pre-exposure prophylaxis (PrEP). The 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. […]
Evidence suggests that the individual in question, a 43-year-old man who has sex with men, adhered well to PrEP over the long-term. Nevertheless, 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. […]
Pharmacy records indicated that the man in the case study had consistently filled his Truvada prescription on schedule. Dried blood-spot testing on a sample taken 16 days after he tested positive for HIV indicated that he had adhered well to Truvada during the previous one to two months, a period that overlapped with the estimated time when he contracted the virus.
The man has since been able to lower his viral load, according to the article, by taking other HIV medications.
PrEP has come under some ridicule for being a drug which allows people to have promiscuous sex without having to worry about HIV infection. Although its supporters say it’s an added form of safety for people who are more at risk of getting HIV; sex industry workers, or a negative testing spouse who is in a relationship with someone who is positive.
Doctor Richard Harrigan director of the lab program at the British Columbia Center for Excellence in HIV/AIDS in Vancouver, Canada, is directly involved with the case but told POZ that it’s not time for hysteria.
“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.” Harrigan added, “This case demonstrates that while PrEP is beneficial, we can’t rely on it to be an infallible magic bullet.”