The story of pre-exposure prophylaxis for HIV - using medications to prevent infection - was anything but easy to understand at the Conference on Retroviruses and Opportunistic Infections.
One study presented here showed it worked well, while another suggested it might not work at all.
But like much in HIV research the two bits of work may not be as contradictory as they appear on the surface.
To sort out the similarities and differences, MedPage Today North American Correspondent Michael Smith discussed the trials with Mitch Warren, executive director of the HIV prevention advocacy group AVAC, in this exclusive InFocus report.
IAS: HIV Prevention Studies Spark Robust Debate
The issue is drugs.
Everyone at the 2011 meeting of the International AIDS Society here agrees that there are not enough available antiretrovirals even to treat all those who will certainly die soon without therapy.
But now there is robust and compelling evidence that expanding treatment would not only help individual patients but also could slow - and perhaps halt - the 30-year-old HIV/AIDS pandemic.
A landmark study, formally presented here for the first time, showed that treatment of HIV patients almost completely blocked their ability to transmit the virus.
The obvious implication was that widespread treatment would slow the relentless pace of infection that drives the pandemic - an implication that was not lost on the audience, which gave the investigators a standing ovation.
But the meeting also has heard positive results from studies of another approach - so-called pre-exposure prophylaxis or PrEP, which focuses on people without HIV infection.
“There is a tension” between advocates of the two approaches, according to Julio Montaner, MD, of the B.C. Centre for Excellence in HIV/AIDS in Vancouver.
By Michael Smith, North American Correspondent, MedPage Today