Nabi Biopharmaceuticals' experimental StaphVAX vaccine is entering its second clinical trial after the first round of tests showed the vaccine, which aims to reduce the risk of Staphylococcus aureus infection, was effective for about 10 months in patients with end-stage renal disease. The company had hoped the vaccine would protect patients for 12 months, and the Food and Drug Administration (FDA) requested that a new trial with an attainable goal be conducted before a decision on approval is made. The new trial will involve 3,300 patients on hemodialysis at 200 sites in the United States. StaphVAX could receive FDA approval as early as 2006.