The more you read about women and HIV, the more depressing it can get. But there is hope on the horizon—closer than you might expect. While HIV vaccines have garnered most of the attention and funding, a more realistic preventive approach for women is microbicides, "chemical condoms" that sabotage the virus.

While condoms are excellent (at preventing the virus from infecting another person), it’s often difficult for women to negotiate the use of condoms," says Betsy C. Herold, MD, professor of pediatrics and microbiology at Mount Sinai School of Medicine in New York and a leading researcher on the use of microbicides to prevent HIV. "It’s imperative that there be alternative strategies available to women for their own health."

Enter microbicides. The microbicide is a substance that will either kill or reduce the infectivity of the virus. Microbicides could be infused into sponges, formed into time-release suppositories or developed as intravaginal rings that work for weeks or months.

Microbicides come with an added bonus: Many are also effective against other sexually transmitted infections, including herpes, chlamydia and gonorrhea.¹¹

Today, five microbicides are being tested in six late-stage clinical trials involving tens of thousands of women in the United States and developing countries. Some work by disrupting the viral envelope, blocking the virus’s entry into cells or making the vagina itself hostile to the virus, while others disrupt the virus’s life cycle.

The trials are expected to wrap up in 2007 at the earliest, says Dr. Herold, at which time the U.S. Food and Drug Administration will consider their approval.

One reason for their commitment, he says, is the respect and caring shown by the study's health care professionals. "They've formed a strong link," he notes. "We're saying that we don't view you as research subjects; you are participants in a study, and hopefully we'll be able to show that this research is relevant to your own lives."

While microbicides show great promise, safety is a major concern. Studies found that one microbicide thought to protect against HIV— nonoxynol-9—actually increased the risk of transmission, because it irritated the lining of the vagina.

Once one or more microbicides are approved, Dr. Herold predicts that future research will focus on developing combination microbicides, "so we can hit the virus at several different steps." This would also help prevent the virus from becoming drug resistant.

"The concept of vaccines is very exciting, and they are our greatest hope for HIV prevention in the long term, but they have a long way to go in their development," Dr. Herold says. One challenge is that the virus attacks the immune response, yet vaccines rely on a strong immune response to prevent infection—a kind of medical catch-22. Another challenge is that the virus is constantly changing. Developing a vaccine that will work long term is like trying to hit a moving target.

Nonetheless, the National Institutes of Health has initiated or conducted more than 75 clinical trials of more than 35 vaccines. Ten new vaccines entered clinical trials in the past two years and six to eight are expected to begin testing within the next 18 months.¹²

However, despite almost twenty years of research and more than $500 million spent in recent years on vaccine research (compared to about $52 million a year for microbicidal research),¹³ a safe and effective vaccine is not likely to be available for at least another five to 10 years, she predicts. X

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