An Answer to a Commonly Asked Question: Is Treatment 100% Effective in Preventing HIV Transmission?
The excitement about "treatment as prevention," and the results of Study 052, have led to many patients asking the question (if not in these words, than using others with a less medical slant), "So if I'm on treatment and doing well, just what is the risk of my transmitting HIV to others?"
It's not a question that's easy to answer, because even though none of the study subjects in 052 with an undetectable viral load transmitted HIV (the one case in the treatment group likely did so before virologic suppression), all the patients were counseled about standard prevention strategies, including condoms.
And we all know that nothing is 100% risk free. Not seat belts, football helmets, highway guard rails, parachutes ...
Just take a look at this case report.
And over in Journal Watch AIDS Clinical Care, Chuck Hicks summarizes two studies highly relevant to this question, and concludes:
Although there is no doubt that ART significantly decreases the likelihood of HIV transmission, these data indicate that the risk for HIV transmission is not eliminated by suppressive ART. Shedding of virus in the male genital tract is not uncommon, even in men with consistently undetectable plasma HIV RNA ... Thus, despite the fact that the threshold level of genital-tract HIV necessary for transmission is not known, caution is warranted. Recommending safer sex (and procreation) practices for all HIV-infected patients, even those with suppressed plasma HIV RNA, seems prudent.
That bolded statement really has to be our standard practice ... right?
Paul Sax is Clinical Director of Infectious Diseases at Brigham and Women's Hospital. His blog HIV and ID Observations is part of Journal Watch, where he is Editor-in-Chief of Journal Watch AIDS Clinical Care.