Food and Drug Administration

In this Thursday, May 10, 2012 photo, Dr. Lisa Sterman holds up a Truvada pill at her office in San Francisco. Sterman prescribes the drug off-label for about a dozen patients at high risk for developing AIDS. The pill, already used to treat people with HIV, also helps prevent the virus from infecting healthy people. The Food and Drug Administration is expected to decide by June 15 whether the pill’s maker Gilead Sciences should be allowed to formally market the drug for preventive use. (AP Photo/Jeff Chiu) (Jeff Chiu)

This Thursday, May 10, 2012 photo shows a bottle of Truvada at the office of Dr. Lisa Sterman in San Francisco. Sterman prescribes the drug off-label for about a dozen patients at high risk for developing AIDS. The pill, already used to treat people with HIV, also helps prevent the virus from infecting healthy people. The Food and Drug Administration is expected to decide by June 15 whether the pill’s maker Gilead Sciences should be allowed to formally market the drug for preventive use. (AP Photo/Jeff Chiu)

In this Thursday, May 10, 2012 photo, Dr. Lisa Sterman holds up a Truvada pill at her office in San Francisco. Sterman prescribes the drug off-label for about a dozen patients at high risk for developing AIDS. The pill, already used to treat people with HIV, also helps prevent the virus from infecting healthy people. The Food and Drug Administration is expected to decide by June 15 whether the pill’s maker Gilead Sciences should be allowed to formally market the drug for preventive use. (AP Photo/Jeff Chiu)

In this Thursday, May 10, 2012 photo, Dr. Lisa Sterman holds up a Truvada pill at her office in San Francisco. Sterman prescribes the drug off-label for about a dozen patients at high risk for developing AIDS. The pill, already used to treat people with HIV, also helps prevent the virus from infecting healthy people. The Food and Drug Administration is expected to decide by June 15 whether the pillâÃÂÃÂs maker Gilead Sciences should be allowed to formally market the drug for preventive use. (AP Photo/Jeff Chiu)

The U.S. Food and Drug Administration (FDA) Antiviral Drugs Advisory Committee holds a meeting to vote on whether Gilead Sciences' Truvada should be approved as a preventative treatment for people who are at high risk of contracting HIV through sexual intercourse May 10, 2012 in Silver Spring, Maryland. Already approved to treat people infected with HIV, Truvada would be a milestone in the worldwide AIDS epidemic by offering a tablet capable of preventing infection in high-risk individuals.

The U.S. Food and Drug Administration (FDA) Antiviral Drugs Advisory Committee holds a meeting to vote on whether Gilead Sciences' Truvada should be approved as a preventative treatment for people who are at high risk of contracting HIV through sexual intercourse May 10, 2012 in Silver Spring, Maryland. Already approved to treat people infected with HIV, Truvada would be a milestone in the worldwide AIDS epidemic by offering a tablet capable of preventing infection in high-risk individuals.

The U.S. Food and Drug Administration (FDA) Antiviral Drugs Advisory Committee holds a meeting to vote on whether Gilead Sciences' Truvada should be approved as a preventative treatment for people who are at high risk of contracting HIV through sexual intercourse May 10, 2012 in Silver Spring, Maryland. Already approved to treat people infected with HIV, Truvada would be a milestone in the worldwide AIDS epidemic by offering a tablet capable of preventing infection in high-risk individuals.

The U.S. Department of Health and Human Services building which houses the Food and Drug Administration (FDA) in Rockville, MD. (Getty Images)