A November 23 report out of the New England Journal of Medicine (NEJM) is showing significant, though nothing close to absolute, protection from HIV transmission through the daily use of Truvada, a single pill combining two drugs, tenofovir (TDF) and emtricitabine (FTC), that is currently used in the treatment of existing HIV infections.
Approximately 2,500 gay and bisexual men, as well as transgender women at high risk for infection, in the US, Brazil, Ecuador, Peru, South Africa, and Thailand, participated in a study by the Pre-exposure Prophylaxis Initiative (iPrEX).
NEJM reports that HIV infections in the half of the group taking Truvada were 43.8 percent lower than among those taking a placebo. Over a median period of 1.2 years, 100 of those on the placebo became infected versus 64 of those on the treatment. The study also found that infection rates were lower among those on Truvada who were consistent in taking their medication every day.
One factor that is likely to temper reactions to the study, however, is that the 43.8 percent improvement has a wide confidence interval. Expected improvements could be as great as 63 percent or as little as 15 percent.
In the US, the two participating trial sites were the San Francisco Department of Public Health and Fenway Health in Boston.
“We had reached a plateau in preventing the transmission of HIV,” said Dr. Kenneth Mayer, Fenway’s medical research director, who was a principal investigator in the trials and co-wrote the NEJM article. “For more than 15 years, the rate of new infections in the US has been stuck at about 56 thousand per year; globally, there are more than 2.5 million new HIV infections per year. There has been no downward movement in this number; which has meant that we desperately needed a new approach. Today’s announcement marks a tremendous step forward — it’s now possible that within the next few years, we can significantly reduce the number of new infections.”
“This study demonstrating partial effectiveness of pre-exposure prophylaxis gives us great hope that effective biomedical interventions are possible,” said Marjorie J. Hill, PhD, chief executive officer of Gay Men’s Health Crisis (GMHC). “Meanwhile, we know that by far the most effective prevention technologies remain condoms and lubricant, and clean needles.”
The Truvada trials employed a number of key risk reduction strategies, including intensive safer sex counseling, frequent HIV testing, condom availability, and treatment of sexually transmitted diseases.
Project Inform, a group that works to empower people living with HIV and AIDS, urged government agencies to “waste no time in assessing the ability of Pre-Exposure Prophylaxis to slow the HIV/AIDS epidemic.” However, it “strongly” urged negative gay and bisexual men not to attempt a pre-exposure course of treatment on their own by securing Truvada from friends who are positive. The group also noted the many unanswered questions about the “real-world delivery” of such a prevention approach, highlighting in particular the risk that a costly drug intervention could widen already yawning gaps between affluent societies and those struggling to contain HIV epidemics in their midst.
Earlier this year, a study among heterosexual women in South Africa found that a 1 percent tenofovir gel reduced HIV transmission 39 percent when compared to a control group taking an inactive placebo gel. That trial, too, emphasized the importance of consistent condom use.
The iPrEx study was sponsored by the US National Institutes of Health through a grant to the Gladstone Institutes, a non-profit independent research organization affiliated with the University of California at San Francisco. The Bill & Melinda Gates Foundation provided additional support.
The federal Centers for Disease Control and Prevention recently announced findings from a 21-city study that showed that nearly one in five gay and bisexual men are infected with HIV, with half of them unaware of their status.