The journal Science has lauded an eye-opening HIV study, known as HPTN 052, as the most important scientific breakthrough of 2011. This clinical trial demonstrated that people infected with HIV are 96 percent less likely to transmit the virus to their partners if they take antiretroviral drugs (ARVs).

The findings end a long-standing debate over whether ARVs could provide a double benefit by treating the virus in individual patients while simultaneously cutting transmission rates. It’s now clear that ARVs can provide treatment as well as prevention when it comes to HIV, researchers agree.

Myron Cohen from the University of North Carolina’s School of Medicine in Chapel Hill, N.C. and an international team of colleagues kicked off the HPTN 052 study in 2007 by enrolling 1,763 heterosexual couples from nine different countries: Brazil, India, Thailand, the United States, Botswana, Kenya, Malawi, South Africa and Zimbabwe. Each participating couple included one partner with an HIV infection.

The researchers administered ARVs to half of those HIV-infected individuals immediately and waited for the other half of the infected participants to develop CD4 counts below 250 – indicative of severe immune damage – before offering treatment. (A CD4 count below 200 indicates AIDS.)

Then, earlier this year, four years […]