The practice of people taking an oral medication to ensure they don't contract HIV if they're later exposed to the virus -- known as HIV pre-exposure prophylaxis or PrEP -- continues to gain acceptance. With PrEP's efficacy firmly established and usage rates steeply rising, the way is being paved for widespread adoption of PrEP as an HIV prevention strategy.
That said, some questions about PrEP linger. For instance, on his "Ask Dr. Joel" Tumblr blog, Joel Gallant, M.D., M.P.H., a renowned HIV physician at Southwest CARE Center in Santa Fe, New Mexico, recently received this question from a reader:
How high is the resistance risk if PrEP is inadvertently started during an acute infection? Are there any studies that have looked at that question?
On July 19, Gallant answered:
I can't give you a number, but it's quite common to develop the M184V (emtricitabine/lamivudine) mutation if PrEP is started during acute infection. The K65R (tenofovir) mutation can also occur, but it's much less common.
Today at the International AIDS Conference in Durban, Bob Grant gave a talk in which he clearly demonstrated that the benefit PrEP in terms of HIV prevention far outweighs the small risk of PrEP-associated resistance. In fact, he ended by saying that if our goal is to avoid resistance, we should be using more PrEP, not less. Infections require treatment, which sometimes leads to resistance. If you prevent infections with PrEP, you ultimately decrease resistance.
Of course, HIV infection appears to be extremely rare among people on PrEP. It wasn't until early 2016 that we saw the first documented case of a person becoming HIV positive despite being fully adherent to a PrEP regimen. However, the concern expressed by the "Ask Dr. Joel" reader focused on a different, uncommon event: people starting PrEP when they were already HIV positive but didn't know it.
Gallant's response suggests that, although people's first-line HIV treatment options could potentially shrink if they were already HIV positive when they began PrEP, those chances are small -- and they shouldn't stop people from beginning PrEP if they feel they might be at risk for HIV in the future.
Joel Gallant, M.D., M.P.H., is the medical director of specialty services at Southwest CARE Center in New Mexico. You can ask him a question directly on his Tumblr page, Ask Dr. Joel.
Myles Helfand is the editorial director of TheBody.com and TheBodyPRO.com. Follow Myles on Twitter: @MylesatTheBody.