Over the next few months, officials in two U.S. cities and several other countries will begin testing whether a popular AIDS drug can protect healthy people against HIV infection.If the tests are successful, they could lead to the first AIDS prevention pill, potentially giving millions of people a way to have sex and avoid infection.The researchers have to resolve many issues first, from questions of cost to concerns about encouraging unsafe sex. But for now, officials are crossing their fingers as the drug studies get under way.
