Drugmaker Gilead Sciences Inc. says federal health regulators have delayed a decision on whether to approve its drug Truvada as the first pill that prevents HIV infection. Gilead Sciences said Friday that the Food and Drug Administration will take an additional three months to review its drug application, after the Foster City company submitted additional materials to the agency earlier this month. In May, a panel of experts recommended approval of the daily pill Truvada for healthy people who are at high risk of contracting HIV. The group’s vote is nonbinding, but the FDA often follows its advice.