We have known about Truvada for a while. Now, an influential advisory panel of the Food and Drug Administration has endorsed the drug shown to prevent HIV infection in healthy people. It recommended approval of the pill for people at risk of contracting the virus. A final decision is expected next month, but if FDA does approve, it won't be without a degree of controversy. We're joined by Dr. Kenneth Mayer, medical research director at Fenway Health in Boston and a professor at Harvard Medical School.