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The New Frontier of HIV Prevention

At this summer’s International AIDS Conference in Vienna, two South African researchers revealed the results of an HIV prevention clinical trial that could herald a new era of HIV prevention efforts worldwide and raise a host of ethical questions regarding resource allocation, health care costs, and preventative medicine. The trial, CAPRISA 004, was the first completed trial to assess the use of an HIV antiretroviral drug as pre-exposure prophylaxis for HIV transmission. The trial investigated whether the antiretroviral drug tenofovir, in the form of a vaginal gel, could protect HIV-negative women from becoming HIV-positive.

The premise of pre-exposure prophylaxis, generally referred to as PrEP, was developed in part from the success of tenofovir and similar antiretroviral drugs at disrupting the life cycle of the human immunodeficiency virus in HIV-positive individuals. Scientists who have developed pre-exposure prophylaxis trials have hypothesized that if a drug such as tenofovir were in the blood stream or genital tract upon exposure to HIV, the virus might be destroyed before it could infiltrate host cells. Thus, an individual exposed to the virus would be protected from becoming HIV-positive.

After years of disappointing trials of hopeful HIV vaccine and microbicide candidates, the scientific, medical, and advocacy community waited eagerly for the results of CAPRISA 004. The outcome was the most encouraging of any biomedical HIV prevention trial to date: based on a 30-month trial involving over 800 women in South Africa, the researchers found that use of a vaginal tenofovir gel before and after sex decreased these women’s risk of contracting HIV by 39 percent. While this trial alone is insufficient evidence to implement PrEP in clinical settings, it demonstrates proof of concept for this type of preventive therapy.

The results of CAPRISA 004 were met by a standing ovation at the Vienna conference. The success of PrEP in this trial represents remarkable new possibilities for abating the HIV epidemic. One of the most important features of PrEP is that it empowers women who often cannot navigate safe sex practices with their partners to take HIV prevention into their own hands. A woman at risk for contracting HIV could insert the gel before and after sex or take a pill daily (different trials test these different models) without her partner being involved or even knowing.

Though not a contraceptive, it could change sexual practices much like oral contraception has over the last several decades in that PrEP, like oral contraceptives, gives women more control over their bodies and sexual and reproductive health. While CAPRISA 004 tested PrEP in women, other trials are examining it in different populations at risk for contracting HIV, such as men who have sex with men and injection drug users who could equally benefit.

Long before the results of CAPRISA 004 were announced, HIV advocates, scientists, and public health officials from the World Health Organization and U.S. Centers for Disease Control and Prevention have been discussing what implementation of PrEP would look like if it is proven safe and effective. Though these conversations have been under way for more than two years, the results of CAPRISA 004 bring new urgency to them.

It is possible that PrEP could change the landscape of the HIV/AIDS epidemic in a way similar to the development of highly active antiretroviral therapy in 1996, which revolutionized what it meant to live with HIV. Once an almost invariably fatal illness, HIV disease became in many respects a manageable, chronic disease with this combination of antiretroviral drugs, although not all people living with HIV have had access to adequate treatment and millions of people have died as a result.

Similarly, if PrEP really works as an effective and safe technique for preventing the transmission of HIV, it could give many at-risk individuals, such as the women from the CAPRISA 004 trial who, without an intervention like PrEP, have a fifty percent chance of contracting HIV by age 24, significant protection from an incredibly harmful virus and a costly disease. But – again just as with antiretroviral therapy – if the people who most need PrEP do not have access to it, then rather than ushering in a new era effective of HIV prevention efforts, we risk simply exacerbating the injustices and inequalities that are already so painfully apparent in the epidemiology of HIV/AIDS.

To address both the great potential of PrEP and its many possible pitfalls, there are many pressing questions to consider, here and around the world. Perhaps the most urgent is, will the people who need PrEP have access to it? But also, who will pay for it? How will at-risk individuals be identified, counseled, and given PrEP in a safe and effective manner? And how will PrEP be integrated into existing and necessary prevention methods such as behavioral modification?

In the U.S., our current political debates around health care reform, especially with respect to disease prevention and health care costs, suggest that HIV advocates’ push for PrEP implementation will be met with intense criticism and debate. As we have sadly learned from three decades of the HIV/AIDS epidemic, all too often the groups most harmed by HIV and AIDS – including poor women of color, intravenous drug users, and gay men – are simply blamed for their “risky” and “immoral” behaviors rather than equipped with the tools to stop the destruction of the HIV epidemic and the social, political, and economic injustices that contribute to its proliferation.

HIV activists and public health researchers and officials are already deeply involved with addressing these questions. But those dedicated to bioethics must also be involved in this conversation as it relates to distributive justice, health care costs, social determinants of health, and many more ethical issues. The success of the CAPRISA 004 trial suggests that in the next few years we will learn how to slow the spread of HIV in an unprecedented way. We need to ensure that this scientific knowledge is used to implement ethical prevention methods that will effectively quell this deadly epidemic.

Colleen Farrell, a 2010 graduate of Williams College, is a research assistant at The Hastings Center.

Published on: September 22, 2010
Published in: Health and Health Care

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