for Veterans and the Public
Frequently Asked Questions
Q: I recently heard about someone who got HIV while taking PrEP. What happened? Should I be afraid to take PrEP?
There are a number of reasons why PrEP (pre-exposure prophylaxis) might "fail," meaning it dosen't protect someone from HIV infection. By far, the most common reason why people may become infected with HIV while on PrEP is they do not take the Truvada medication every day, as prescribed. In fact, nearly every one of the PrEP "failures" reported to date has been in people who were not taking Truvada regularly or who had very low levels of the drugs in their bodies (suggesting that they were not taking the medication as prescribed).
But in 2016, we learned about a couple of individuals who became infected with HIV even though they had been taking PrEP for many months and are thought to have taken their Truvada very consistently, every day. It is not completely clear why these people became infected, but it appears that they were infected with HIV viruses that already had a lot of resistance mutations, which made the PrEP medications less effective.
It is important to know that this is a very unusual scenario -- there are few HIV-positive people with highly resistant virus, and the PrEP medications are very effective in preventing infection with the typical non-resistant HIV strains. So, these cases should not stop you from using PrEP. But, it is good to remember that PrEP is not 100% protective against HIV. That's why we recommend you take Truvada every day, and also use condoms, for extra protection.