What if women could take a pill to decrease the chance of infection during sex with an HIV-positive partner?
In fact, such a therapy exists, and in a recent paper, Harvard researchers say it merits a closer look. They do not recommend its widespread use, but rather, assuming that ongoing studies demonstrate its efficacy, argue that it stands to help committed couples in which one partner is infected and the other is not, and who wish to have a child. The approach may prove most useful for couples in which the man is infected and the woman is not; a different method exists to prevent transmission between a woman with HIV and a man who does not have the virus (see below).
"Pre-exposure prophylaxis," or PrEP—in which the uninfected partner takes antiretroviral medications (ARVs) to avoid infection even when she is exposed to the virus—became possible recently with the development of drugs that are more effective and have fewer severe side effects.
The lead author, clinical fellow in medicine Lynn Matthews, is studying the fertility choices of people with HIV in South Africa. Her coauthor and research mentor, David Bangsberg, directs the Center for Global Health at Massachusetts General Hospital and directs a program in Uganda that helps alleviate poverty for people living with HIV.
The notion of prescribing ARVs—specifically, the drug tenofovir—to people who don't have HIV is controversial for a number of reasons, Matthews and Bangsberg acknowledge. First, it is difficult enough to get ARVs to people who do have HIV: in South Africa, it is estimated that just one-third of HIV patients who need ARVs are receiving them. And someone who becomes infected even with PrEP may quickly become resistant to an important category of drugs for treatment.
In addition, PrEP is so new that its efficacy is still being evaluated. And another effective precautionary method does already exist: namely, putting the infected partner on ARVs and waiting for the drugs to bring down the viral load in his body. A recent meta-analysis didn't turn up a single documented case of transmission between couples when the infected partner's viral load was suppressed below 400 viral copies per milliliter of blood.
But PrEP offers added insurance—and it places agency in the hands of women, releasing them from reliance on a partner who may not have adhered to his medication regimen, or who may refuse even to be tested for HIV—or who isn't yet sick enough to qualify for treatment. People with HIV qualify for ARVs only when their immune-cell count drops below a certain level, indicating that the immune system is starting to lose the fight against the virus.
(For couples in which the woman is infected and the man is not, a different solution exists: they can practice artificial insemination at home. Matthews's research will examine people's attitudes about this practice, and social factors that may inhibit its use.)
The authors don't support widespread use of tenofovir in the general population. The approach is not currently in use in the developing world, except as part of research studies; some physicians in the United States are using tenofovir this way as an off-label use, Matthews says. One study of PrEP in Italy achieved a 50 percent pregnancy rate with no transmission between partners or from mother to child. However, in this study, the infected partners were taking ARVs to suppress their viral load.
The authors focus on committed, monogamous couples because, they report, most HIV transmission in sub-Saharan Africa (an estimated 60 percent) occurs—contrary to many stereotypes—within such relationships. They write that, as ARVs have allowed HIV patients to stay healthier and live longer, the patients have stopped seeing the disease as a death sentence, and have become more interested in starting families. At the same time, the development of effective drugs has made mother-to-child transmission almost entirely preventable.
Beyond PrEP, the authors espouse a wider shift to a patient-centered approach, in which doctors consider patients' desires and work out a collaborative treatment plan. In the past, doctors typically advised HIV patients to forgo having children. Many patients ignored this advice; aside from the normal desire to have children with one's spouse, cultural factors influence these decisions: in southern Africa, girls signal their fertility and boost their marriage prospects by getting pregnant at a young age, the authors write. An approach that acknowledges these factors could have the secondary but important benefit of drawing more people into the healthcare system by building trust.
The opinion piece, coauthored with Jared Baeten and Connie Celum of the University of Washington, was published in the journal AIDS on August 24.
