Breakthrough Research
By Linda Villarosa
What if there was a pill that could be taken once a day to prevent the spread of HIV? That idea may not be as Orwellian as it sounds. Scientists are studying that idea, known as pre-exposure prophylaxis or PREP, as well as many other new innovations in HIV/AIDS prevention.
At a special session during the XVI International AIDS Conference called “Prevention: Proven Approaches and New Technologies,” Dr. Helene Gayle, president of the International AIDS Society, hosted a highly-anticipated panel of experts from around the world that took a hard look at the successes, failures and future of HIV prevention. All week, attendees at the XIV International AIDS Conference were buzzing about the newest forms of prevention—PREP, circumcision, microbicides and vaccines. Later in the day, the Global HIV Prevention Working Group, a consortium of respected experts, released a detailed report that examines new approaches to HIV prevention. “The data we are seeing this week highlight the urgent need to accelerate prevention research and expand the number of options available to us,” said Gayle, who is also co-chair of the prevention working group. Prevention has taken center stage at this conference, at least partly due to the attention on the issue from both of the Bills—Clinton and Gates—and the huge sums of money the Bill and Melinda Gates Foundation have funneled toward efforts to stop the spread of the virus. Over the past decade, the Gates’ have donated $1.9 billion to fight AIDS, and their new focus is on developing prevention approaches, including new medications and a vaccine. Attention toward prevention is desperately needed. In 2005, 4.1 million people were newly infected with HIV, and over 40 percent of those new infections in adults occurred in young people ages 15 to 24, the UNAIDS reports. The organization also estimates that HIV/AIDS prevention services reach only an estimated one in 10 of those in need. In the U.S., prevention policy is in near total disarray. Though the federal government vowed to cut the rate of new infections in half by 2005, the number has remained constant—40,000 new cases a year. African Americans represent half of new AIDS infections. One of the key ways to curtail the spread of HIV is through sex education. But that effort has been hampered in the U.S.—and around the world—by American policies that tie funding to the teaching of abstinence only in poor nations and in the U.S. “There is no solid evidence that abstinence only programs have any effect on HIV risk reduction,” says Dr. Judith D. Auerbach, vice president of public policy and program development at amfAR and a member of the prevention working group. “What we know that works is postponing the onset of intercourse, reducing the number of sex partners and increasing condom use. That is very different from saying you should never have sex outside of the context of heterosexual marriage.” Even as experts and philanthropists look beyond traditional methods of prevention toward new technologies, others stress that the only way to prevent the spread of HIV is through a combination approach that includes sex education, counseling and testing. “With all of the advances in prevention technology, we have to be careful to avoid the medicalization of prevention,” said Dr. Cristina Pimenta, executive director of the Brazilian Interdisciplinary AIDS Association, who took part in the prevention panel. “Potentially promising biomedical interventions, such as pre-exposure prophylaxis, circumcision and microbicides are not magic solutions. They should be considered complementary, not as stand-alone interventions.” The gold standard of HIV prevention is a vaccine that would help the body fight off the virus. Second choice: A vaccine that works like antiretroviral medication to suppress the amount of virus circulating in the body and lower the risk of someone who is positive transmitting the virus to a sexual partner. An effective vaccine, however, is a long way off. Several years ago, the only candidate to complete the full course of clinical trials was found to be ineffective. Thirty HIV vaccine candidates are currently being studied, but experts predict that an effective vaccine is at least 10 years away. Says Dr. Helene Gayle: “We know we will have a vaccine someday, but we have stopped predicting whether it’s five years, 10 years, 15 years away.” Take a look at three of the most promising new prevention technologies: Circumcision How it works: The surface of the foreskin of the penis contains cells that are highly susceptible to HIV infection. Removing the foreskin may reduce the risk of acquiring and transmitting HIV during sexual intercourse. What the research says: A trial of over 3,000 South African participants found that men who were circumcised had a 60 percent lower risk of acquiring HIV from their female partners than uncircumcised men. Three more large-scale circumcision trials are underway in Africa with results due in 2007. Pros: Circumcision is a one-time procedure that could offer a life-time benefit. Drawbacks: It must be performed by a trained practitioner, and no matter who does it, it hurts. Circumcision has been shown to reduce female-to-male transmission, but more research is needed to know if it reduces male-to-female transmission which is the more urgent problem. Bottom line: Used with other prevention methods it could lower the risk of HIV transmission. Circumcision, however, would not make a huge difference in the U.S. where most men are already circumcised, though African-American rates are lower. Microbicides How they work: Microbicides are creams, foams, gels or other topical substances that a woman can apply to the vagina or rectum before sex to stop HIV infection. Some also prevent pregnancy. What the research says: There are currently 30 products in development and five are being studied for effectiveness in very large groups of women. Results could be available by 2008. Pros: Microbicides are controlled by women and can be used without her male partner’s knowledge or cooperation. Bottom Line: Getting a product out has been very slow. Even if current studies pinpoint a microbicide that works, it probably wouldn’t hit the market until 2010. Pre-Exposure Prophylaxis (PREP) How it works: Anti-retroviral drugs have prolonged the lives of people living with HIV/AIDS. Some antiretroviral medication is also given to people—mainly health care workers--who have been exposed to HIV after exposure to reduce the risk of transmission of the virus. Now scientists are studying whether an uninfected person can take a once-a-day antiretroviral pill to prevent contracting HIV. What the research says: Studies of monkeys have shown promise. Large-scale PREP trials are underway in Botswana, Peru and Thailand with results expected between 2007 and 2008. Pros: Taking medication to prevent HIV, like you might take the birth control pill, sounds great, especially for individuals involved in high-risk activities like sex workers and injecting drug users. Drawbacks: Medication is expensive and there isn’t enough for everyone who needs it for treatment. Plus, resistance is a problem with all kinds of antiretroviral drugs. Bottom Line: Even if studies show that PREP works, it’s best used in combination with other prevention methods, like condoms. Linda Villarosa is a freelance writer from Brooklyn, N.Y.
Promising Prevention Approaches