A Pill a Day Reduces Risk for HIV Infection

A Pill a Day Reduces Risk for HIV Infection

San Francisco - A new HIV prevention strategy that has the potential to slow the global HIV epidemic has been proven effective in a new research trial. The iPrEx Study showed that HIV negative people who were given a daily HIV treatment drug had 44% fewer HIV infections than those who received a placebo. The study, reported in the New England Journal of Medicine, is the first evidence that this new HIV prevention method, called pre-exposure prophylaxis or PrEP, reduces HIV infection risk in men who have sex with men and transgender women who are at high risk for HIV infection. The drug used in the trial is known as Truvada®, a commonly used HIV treatment pill that is a combination of emtricitabine and tenofovir.

The HIV Research Section of the San Francisco Department of Public Health (SFDPH) enrolled 140 participants into this groundbreaking study, which was known locally as Prepare.

Worldwide, a total of 2,499 individuals participated in the six-country study. All study participants received a comprehensive package of prevention services designed to reduce their risk of HIV infection throughout the trial, including HIV testing, intensive safer sex counseling, condoms, and testing and treatment for sexually transmitted infections. Half of the study participants also received the PrEP pill, while the other half received a placebo.

In all, 64 HIV infections occurred among the 1,248 study participants who received the placebo pill, while 36 HIV infections occurred among the 1,251 participants who received Truvada®. The average reduction in HIV infection risk of 44% includes all study participants - even those who did not take the daily pill consistently. All studies have some uncertainty -- based on evidence from this study, the likely range for the overall protective effect of Truvada® is between 15% and 63%.

The iPrEx study found that PrEP offered more protection to those who reported taking the pill more consistently. Pill use in the study was measured through pill counts, bottle counts, and participants' self-reports. Among those who took the drug on 50% or more of days, risk of HIV infection fell by 50% (95% CI 18-70%); among those who used the pill on 90% or more of days, the PrEP pill reduced infection risk by 73% (95% CI 41-88%).

In addition to pill-taking measures that rely on self-reports, iPrEx also measured levels of Truvada® in the blood of study participants. These tests corroborated that participants who were protected against HIV infection were likely taking the study drug more regularly. Among a subset of 77 study participants who were given Truvada®, detectable levels of the drug were found in the blood of 51% (22 of 43) of those who remained HIV uninfected, but in only 9% (3 of 34) of participants who became HIV infected. Low or absent drug levels underlie all of the infections that occurred among those who received active PrEP.

"iPrEx 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," said iPrEx Protocol Chair Robert Grant, MD, MPH of the Gladstone Institutes and the University of California at San Francisco. "As with other prevention methods, the greatest protection comes with consistent use. I hope this finding inspires a renewed commitment from communities, industry, and government to stop the spread of HIV." "These study results are an historic step forward in developing effective prevention strategies for men who have sex with men and transgender women, populations that are heavily impacted by the HIV/AIDS epidemic worldwide," said Susan Buchbinder, MD, Director of the HIV Research Section. "The study could not have been completed successfully without the collaboration of our community partners, and the commitment of study participants here in San Francisco, and on 4 continents. We look forward to continuing to work with them all as we move forward to better understand how and for whom PrEP might be implemented."