He claims that at the time he was adhering to a daily regiment of Truvada (tenofovir/emtricitabine) as pre-exposure prophylaxis (PrEP).
POZ reports that scientists have come to the conclusion that it’s indeed possible to contract HIV even when adhering to PrEP, when exposed to a strain of the virus that’s resistant to both drugs included in Truvada.
While it’s concerning, experts are suggesting failures like these will be rare.
David Knox, MD is an HIV specialist at the Maple Leaf Medical Clinic and the head author of the case study.
The findings were first presented at the 2016 Conference on Retroviruses and Opportunistic Infections (CROI) in Boston.
The 43-year-old man had sex with men while taking PrEP once a day.
But after 2 years on Truvada, he tested HIV-positive.
Preliminary tests suggest he was acutely infected.
The man tested positive for the p24 antigen, which surfaces within roughly three weeks of HIV infection and disappears several weeks later.
It was then that he tested negative for HIV antibodies, which typically appear two to eight weeks after infection.
According to POZ:
Research suggests that men who have sex with men (MSM) who take Truvada at least four times a week are more than 99 percent protected against HIV. (CDC guidelines advise taking Truvada daily for maximum protection, but the drug apparently has a good amount of dosing “forgiveness.”) Real-world use of Truvada as HIV prevention has suggested it is indeed highly effective. For example, none of the more than 1,400 generally high-risk individuals taking PrEP through the Kaiser Permanente San Francisco PrEP program have contracted HIV to date, despite their very high rate of other sexually transmitted infections, including hepatitis C virus (HCV) in two of them.
All of PrEP’s power to curb HIV notwithstanding, this new case study underlines the fact that in science there is, unfortunately, no 100 percent guarantee.”
Robert M. Grant, MD, MPH, a professor at the University of California, says, “After 32 years of experience with HIV research, I have learned never to say ‘never’… yet I also think that gay men benefit from feeling safer during sex, and I am grateful that PrEP affords that feeling.”
Pharmacy records demonstrate the man did indeed fill his Truvada prescription regularly.
“This person claims he was taking PrEP every day and I believe him,” said Grant.
Tests suggest the man contracted the virus from a single individual, and while his virus was resistant to multiple drugs, he’s continuing HIV treatment and has a fully suppressed viral load.
Research indicates that resistance to tenofovir, the most commonly prescribed ARV in the world, is increasing. What’s rare is a virus that’s resistant to both tenofovir and emtricitabine, as in this particular case report.
According to Richard Harrigan, PhD, director of the lab program at the British Columbia Center for Excellence in HIV/AIDS in Vancouver, Canada, who was one of the researchers on this case study, “I think we would assume that the efficacy of PrEP would be lower if there is exposure to virus which is resistant to either drug, and lowered further if there is exposure to virus resistant to both drugs.”
“This case demonstrates that while PrEP is beneficial, we can’t rely on it to be an infallible magic bullet.”
