Years ago, when scientists predicted that someday you would be able to take a pill once a day to keep from contracting HIV, that idea sounded more Orwellian than real.

But the future is now.

The results of a large, international clinical trial published online this morning in the New England Journal of Medicine found that a daily dose of an anti-retroviral pill reduced the risk of contracting HIV by 43.8 percent. The study, known as iPrEx, found even higher rates — 72.8 percent effectiveness — in participants who adhered most closely to their daily drug regimen. Pre-exposure prophylaxis, or PrEP, as it's known, includes the use of tenofovir, a medication that is already effective in treating HIV infection.

In the scientific world, these findings signal a major coup. Those in the field say that this is the best news since this summer's breakthrough results of a microbicide gel that proved highly effective for preventing HIV in women. That news electrified both the scientific community and the media last summer — Christmas in July in a 30-year pandemic that has offered up few wins.

This time the big win is for men. "The iPrEx study provides important evidence that PrEP works to reduce HIV infection risk among gay and bisexual men," says Robert Grant, M.D., M.P.H., an associate professor of medicine at the University of California, San Francisco, who chaired the study. "The need for new HIV prevention methods is critical. PrEP, in combination with other prevention methods, such as HIV testing, counseling and consistent condom use, could represent a major step forward for efforts to control the global epidemic.”

The iPrEx study involved 2,499 men who have sex with men — called MSM, in public health circles — and transgender women who have sex with men at 11 sites in Brazil, Ecuador, Peru, South Africa, Thailand and, within the United States, San Francisco and Boston. Between 8 percent and 9 percent of study participants described themselves as black, either from the U.S. or South Africa. Around the world, including in Africa and Asia, gay and bisexual men are often at highest risk.


IPrEx is one of the largest HIV-prevention trials to focus on men who have sex with men, the first HIV-prevention study looking at men in either Africa or Asia, and the first time a method using medication has been shown to prevent infection in MSM. MSM account for nearly half of the people living with HIV in the U.S. and 53 percent of all new infections.

Launched in 2007, the research was sponsored by the National Institute of Allergy and Infectious Diseases through a grant from the David Gladstone Institutes, a nonprofit group in San Francisco. In the study, participants were randomly assigned to receive either a daily anti-retroviral tablet containing tenofovir and emtricitabine (brand name Truvada) or a placebo.

This kind of study, known as double blind, since neither the researchers administering the study nor the participants knew who was receiving medication and who was receiving a placebo, is considered the gold standard of research. In the end, 36 HIV infections occurred among the 1,251 participants who received the anti-retroviral therapy, compared with 64 HIV infections among the 1,248 participants who received the placebo. The study also found this method to be safe.


Fauci and others are careful to temper joy with caution. Forty percent or even 70 percent effectiveness isn't the same as 100 percent. "No single HIV-prevention strategy is going to be effective for everyone," adds Fauci, "and it is important to note that the new findings pertain only to the effectiveness of PrEP among men who have sex with men and cannot at this point be extrapolated to other populations."

The finding holds promise for black Americans, who account for 45 percent of the more than 56,000 new HIV infections that occur in the United States each year — particularly for black MSM, who make up 18 percent of new annual infections. "Black communities need as many weapons in our efforts to fight HIV and AIDS as possible," says Phill Wilson, president and CEO of the Black AIDS Institute. "This study shows that there is a possibility to develop a new weapon. That is extremely important." 

The general concept of PrEP has had its critics. Some worry that PrEP could turn into a party pill, something you take before a night of unprotected fun — especially since it works best in HIV-negative people whose sexual practices place them at high risk of becoming infected.


"I can hear in my head people saying, 'This is just another way to let those irresponsible homosexuals have sex,' " Jeffrey Crowley, director of the White House Office of National AIDS Policy, once remarked during a hearing about PrEP. "We have to be conscious of the political risk."

However, in the iPrEx study, participants, who were provided with HIV-prevention counseling and testing, showed a significant decrease in HIV risk behavior. The reported numbers of partners decreased and condom use increased, whether the subjects were taking the placebo or the anti-retroviral pill.

Access to treatment has also been part of the PrEP debate. Around the world, 33 million people live with HIV/AIDS — more than 1 million in this country — and the majority of those infected don't have access to lifesaving treatment. So is it fair to use desperately needed medication for prevention rather than to save lives — especially when anyone can walk into a drugstore and buy a package of condoms? Also, scientists worry that people could become resistant to the drug. Tenofovir, the researchers noted, is less likely to create resistance than many other anti-retroviral medications.


In the wake of today's research, scientists are already working to figure out how these findings will best translate into real life, for real people.

"It's critical for black people to be engaged as this research unfolds and this strategy is developed. We have to be at the table," Wilson notes.  

Meanwhile, correct and consistent condom use and a reduced number of sexual partners remain the most effective ways for gay and bisexual men — and everyone — to protect against HIV infection. 


Linda Villarosa is the program director of the journalism department at the City College of New York and is contributing to a documentary about HIV/AIDS in black America.

This article originally ran in the newsletter for the Black AIDS Institute.