Preexposure prophylaxis may well be the next hope in preventing HIV infections. PrEP, which involves giving anti-HIV drugs like Viread or Truvada to HIV-negative people before they engage in risky sexual behavior to prevent them from becoming infected with the virus, was a hot topic at this year's international AIDS conference; the participants were eager to hear how the process could be effective slowing the spread of HIV. Basically, the concept is similar to women taking daily birth control pills to prevent pregnancy, and there have been several trials in monkeys to show that PrEP might actually work.
When a person becomes exposed to HIV in their genital tract or mouth, the virus has to first attach to the surface of the mouth, vagina, or anus. After it does this, then the virus gets taken up by immune cells and starts to multiply. In the presence of a drug like Truvada, the virus's ability to multiply would be stopped before the virus has a chance to penetrate deeper into the tissues and cause infection in the blood. When HIV enters the blood stream, infection is then established and cannot be prevented. So the concept behind PrEP is to stop the infection before it enters the blood stream.
Right now, there are several PrEP studies under way both in the United States and abroad. Participants in these studies will be divided into two groups. One will take either Viread or Truvada daily, and the other will receive a placebo. Investigators will then follow the study participants over time and see who becomes infected and who does not. PrEP would be successful if less or none of the people taking Viread or Truvada become infected.
Some doctors and scientists are concerned that people in the trial will think that they are 100% protected and let their guard down, possibly engaging in riskier sexual activities. Another concern is how well they will adhere to taking the medication on a daily basis. If one or both of these occur, then PrEP may not work as well.
As was recently reported by the Center's for Disease Control and Prevention, the number of new HIV infections over the past decade has been 40% higher than previously thought. And HIV prevention efforts in this country have largely failed. Currently in the United States, we have approximately 60,000 new infections every year. The vast majority of these occur in African-Americans and gay men. We desperately need new strategies to help us prevent new infections
As many researchers have stated, PrEP would be not just about giving out a pill but also allowing health care professionals to also have an ongoing conversation about sexual behavior. Some of the potential setbacks with PrEP are the cost and the possible side effects from the medications. Right now the cost of Truvada in the United States is about $10,000 a year. While many people and insurers are willing to pay that to save someone's life, they may not be willing to pay that for prevention when a condom would do the same job for a lot less money.
I believe it is now that we have to keep an open mind about new strategies on HIV prevention. Given the recent failures of vaccines and microbicides, PrEP in combination with other prevention technologies, such as condom use and circumcision, are likely to reduce the number of new HIV infections both in the United States and abroad.
Urbina is an HIV specialist and the medical director of HIV education and training at St. Vincent's Comprehensive HIV Center as well as an associate professor of medicine and an associate professor of clinical public health at New York Medical College.
