WASHINGTON  - The first-ever daily pill to help prevent against HIV was approved Monday by US regulators for use in uninfected adults who are at risk for getting the virus that causes AIDS. Truvada, made by Gilead Sciences in California, has been on the market since 2004 and was approved by the Food and Drug Administration for a new use as a tool to help ward off HIV in otherwise healthy people. The pill as pre-exposure prophylaxis (PrEP) has been hailed by some AIDS experts as a potent new tool against human immunodeficiency virus, but some health care providers are concerned it could encourage risky behaviour. In addition, the regimen is estimated to cost around $14,000 per year, making it out of reach of many. "Truvada alone should not be used to prevent HIV infection," said Debra Birnkrant, director of the division of antiviral products at the FDA. "Truvada as PrEP represents another effective, evidence-based approach that can be added to other prevention methods to help reduce the spread of HIV."