Results from a multicountry clinical trial, sponsored by the National Institute for Allergy and Infectious Diseases (NIAID), show that HIV-positive people who take combination antiretroviral therapy (ART) can reduce the risk of transmitting the virus to their HIV-negative partners by 96 percent, U.S. researchers announced on Thursday “[i]n what is being hailed as a breakthrough in HIV prevention,” the Los Angeles Times reports (Maugh, 5/13).

The randomized controlled trial, run by the HIV Prevention Trials Network and named HPTN 052, was meant to run another four years, but an interim analysis by an independent monitoring group prompted NIAID to halt the trial and release the results, ScienceInsider writes. The study, conducted since 2005 at 13 sites in nine countries, recruited 1,763 couples, 97 percent of whom were heterosexual, in which one partner was HIV-positive at enrollment. None of the HIV-positive partners had taken ART, and their CD4 cell counts, a measure of the immune system’s health, were between 350 to 550. “Half the participants received immediate treatment, and the other half did not start [therapy] until their CD4 count dropped to 250 or they developed an AIDS-related symptom, according to ScienceInsider (Cohen, 5/12).

Analysis “identified 39 new cases of HIV among the previously uninfected partners. In 28 of these cases, genetic analysis confirmed that one partner had infected the other. Of these 28 infections, 27 – or 96 percent – occurred among couples in which the HIV-infected partner did not start antiretroviral therapy immediately,” HealthDay/U.S. News reports (Reinberg, 5/12). The couples were all counseled on safe sex practices, given free condoms and provided treatment for sexually transmitted infections, BBC News adds (Gallagher, 5/12).

“This new finding convincingly demonstrates that treating the infected individual – and doing so sooner rather than later – can have a major impact on reducing HIV transmission,” NIAID Director Anthony Fauci said in a statement (5/12).

The New York Times notes that though the trial was “relatively large,” there are limitations to interpreting the results for other populations, like men who have sex with men, because nearly all “of the couples in the trial, who lived in Botswana, Brazil, India, Kenya, Malawi, South Africa, Thailand, the United States and Zimbabwe, were heterosexual” (McNeil, 5/12).

Treating HIV-positive participants early also improved other health outcomes, the Los Angeles Times reports, noting that the results showed 17 cases of disseminated tuberculosis (TB) among those whose treatment was deferred compared with three cases among the treatment group (5/13). According to Bloomberg News, researchers will continue to monitor study participants to determine whether treatment benefits persist (Cortez/Bennett, 5/13).

Treatment As Prevention

“Until now, antiretroviral therapy was known to improve the health of people infected with human immunodeficiency virus, but this is the first study to show a solid impact on preventing transmission to an HIV-negative partner,” Agence France-Presse reports (Sheridan, 5/12).

Though the preliminary results “are likely to end, or at least diminish, a bitter feud within the AIDS world over how much funding should go to treatment versus prevention,” funding “will be a major obstacle,” the Wall Street Journal writes. With more than five million HIV-positive people on treatment at the end of 2009, and another 10 million in need of the drugs based on international treatment guidelines, UNAIDS has estimated a treatment funding shortfall of more than $7.5 billion, the Wall Street Journal notes (Schoofs/McKay, 5/12).

Observational studies have shown a benefit to early HIV treatment, leading UNAIDS last year to adopt “as its goal” a “test and treat” policy that “encourages doctors to start people on treatment as soon as they test positive for HIV,” the New York Times states. Still, “[f]or lack of money, clinics in Africa are turning away patients who are not just infected but close to death. And in some American states where money provided by the Ryan White Care Act has run out, poor uninsured people are on waiting lists,” the newspaper adds (5/12).

UNAIDS Executive Director Michel Sidibe said, “This breakthrough is a serious game changer and will drive the prevention revolution forward. It makes HIV treatment a new priority prevention option,” adding, “Now we need to make sure that couples have the option to choose treatment for prevention and have access to it,” according to Reuters (Steenhuysen, 5/12). Sidibe said “he hopes the new results will compel pharmaceutical companies to lower the price of ARVs as the demand for the drugs expands,” that “new partnerships will form to advocate for increased funding and that the findings will be prominently discussed next month at the United Nations High Level Meeting on AIDS in New York City,” ScienceInsider reports (5/12).