What if you could use a product -- and not a condom -- to prevent getting infected with HIV? What may seem like a fantasy is now edging closer to reality.

This week at the XVIII World AIDS Conference in Vienna the exciting South African CAPRISA study showed that using a microbicide gel containing an anti-retroviral (ARV) drug before and after sex can prevent HIV in women at least 39% of the time. Many believe this good news is a major step in the notion of "treatment as prevention."

"[The CAPRISA study] folds into an even grander dream which is PreExposure Prophylaxis (PrEP), an oral pill that an HIV-uninfected person takes to prevent infection," said Science magazine reporter Jon Cohen in an interview on Tuesday. "It's a hugely promising approach because this says if [the microbicide] works, then [PrEP] has a highly likelihood of working. And if PrEP works, then we have a whole new way to look at treatment as prevention."

Giving those who are not infected with a disease medicine to prevent it is not a new concept. This is how malaria is prevented. But around HIV specifically, the science hasn't yet proven that it's an effective or practical form of prevention-though the success of the microbicide research is raising expectations. Over the six-day conference in Vienna a number of panels discussed PrEP. Despite plenty of hope, no definitive answers emerged in response to the questions surrounding its use.

Researchers have looked at PrEP as a way to stop the spread of HIV since 2004. Most PrEP strategies ask people to take medication, specifically tenofovir or tenofovir-emtricitabine, on an ongoing basis. These AIDS drugs are only taken once per day and have the least side effects. In fact, tenofovir was used in the CAPRISA study. PrEP shouldn't be confused with PEP, Post-exposure Prophylaxis, where someone who thinks they have been recently exposed to HIV takes ARVs after exposure to decrease their risk of acquiring the virus.


PrEP, if successful, would benefit all at-risk populations, but is especially promising for women who bear the weight of the epidemic the world over. PrEP, like microbicides, addresses an urgent need for a female-controlled HIV prevention method for women. Because of poverty, threat of violence, or cultural issues, women have few ways to protect themselves.

"Protection from transmission would not have to be negotiated with partners who are reluctant or unwilling to use a condom," says Dr. Mabel Bianco, about PrEP. She is the coordinator of the International AIDS Women's Caucus. "The choice would be in the hands of women. This has the potential to vastly impact the pandemic."

Currently scientists are conducting more than a dozen trials in high-risk populations around the world, including in Botswana, Brazil, Ecuador, Kenya, Malawi, Peru, South Africa, Tanzania, Thailand, Uganda, the United States and Zimbabwe. The U.S.-based Centers for Disease Control (CDC) is sponsoring PrEP trials in Thailand in IV drug users, and in the United States with MSM populations.

As with anything experimental, there are some concerns around PrEP including the side effects of taking an ongoing drug, possible drug resistance and lowered effectiveness if people miss a dose. Experts also worry that PrEP for HIV may encourage risky behavior in individuals taking it. Yet, access to the drug itself has triggered the biggest controversy around PrEP. If there is already limited access to funds for treatment of HIV and AIDS -- as activists have been insisting loudly all week -- will those not infected take life-saving drugs away from those who are living with HIV and need it to survive?

"That's a valid concern," notes Jim Pickett, of the AIDS Foundation of Chicago and chair of International Rectal Microbicide Advocates. "If [PrEP] is proven to be effective how do we square that in a setting where people who are HIV positive don't have full access to treatment? Who do you decide gets the tenofovir? These are questions we are trying to ask ourselves in the field right now."

Jon Cohen, on the other hand, thinks that even talking about money at this early stage is "illogical."

"The argument that prevention somehow competes with treatment funding is kind of the oldest silliest argument in the field," he says. "I understand why people are worried. They want more money for treatment. Yet I don't think that argument makes sense."

He urges patience. "We have to see what the clinical trials show, if it works and how it works under what conditions," Cohen says. "Then let's worry about the money. I hope we have that problem. It would be a terrific problem to have."

As PrEP research continues to move forward, Dr. Bianco keeping the focus squarely on those methods that have actually been shown to work. "If we can continue to improve both the effectiveness of the microbicides and promote both male and female condoms, this could mean in five years women may actually have choices," she says.