PrEP is pre-exposure prophylaxis—essentially, the idea that, by giving high-risk people HIV drugs before they come into contact with the virus, physicians can prevent them from contracting HIV at all. It has been a much-discussed topic in HIV research for some years, because of its potential to reach high-risk people who are resistant to changing their sexual habits. Now, researchers are effectively leaping with joy, because the results of a PrEP study conducted since 2007 and including some 2,500 men who have sex with men (MSM) in several countries (Brazil, Ecuador, Peru, South Africa, Thailand and the U.S.) have revealed an overwhelmingly positive effect.
The results of the study (called iPrEx, or the Pre-exposure Prophylaxis Initiative) are published in the New England Journal of Medicine. It was conducted by the National Institute of Health's Institute of Allergy and Infectious Diseases. Here's what they found: the overall risk reduction was about 44%, including men who sometimes forgot to take their pill. But break those numbers down by the regularity of the dose, and the numbers become even more astonishing. Men who took the pill 90% of the time (at least nine days out of 10) had a 73% reduced rate of HIV over placebo pills. Yet more overwhelming, men who took the pills every single day, to the point where the Truvada was detectable in their blood, cut their HIV risk by 92%. In HIV research, where results are often frustrating and ambiguous, that is simply an incredible result.
Not surprisingly, the HIV medical and scientific community is cautiously thrilled at the result of the study —but no one is suggesting an end to traditional prevention methods by any stretch of the imagination. "The iPrEx study proves that PrEP provides important additional protection against HIV when offered with other prevention methods such as HIV testing, counseling, condom use, and management of sexually transmitted infections," says study co-chair Robert Grant MD, MPH, of the Gladstone Institute and the University of California, San Francisco. And indeed, participants in the study were given access to a wide array of prevention tools along with the pills, including testing, counseling, treatment, and condoms. Finally, the NIH reports that, "Although there was concern at the launch of the study that the PrEP approach could cause study participants to relax their use of condoms and safe sex practices, this was not the case during the iPrEx study. Rather, participants reported a decrease in the number of sexual partners and increased use of condoms." And it's worth noting that the condoms are a lot cheaper—daily Truvada will run upwards of $5,000 per year.
Curious now about PrEP? Read our PrEP primer and learn more about the science behind the study.