A complicated list of who should get [swine] flu vaccine in the fall is now set. When the vaccine starts arriving in September, first in line will be pregnant women; the caretakers of infants; children and young adults; older people with chronic illness; and health-care workers. That's the advice of a 15-member committee of experts, which met all day Wednesday at the Centers for Disease Control and Prevention in Atlanta to advise the federal government on vaccine policy. The priority list names targeted groups and suggests the order in which they should be vaccinated. The results of this meeting will kick planning into high gear," said Pascale Wortley of the CDC's Immunization Services Division. "This is a watershed moment." All that's missing is the vaccine, knowledge of how well it works and the nitty-gritty details of how to deliver it to people's arms and noses. The vaccine will come in two forms: the traditional flu shot and a "live" vaccine squirted into the nose that contains a weakened version of the new virus. Some of the vaccine will be stored in multi-dose vials containing thimerosal, an antibacterial additive that contains mercury. But there will also be single-dose syringes without thimerosal, a substance that some assert is harmful to children. Among the many unanswered questions is whether two doses will be necessary to provide full protection, how close in time two shots can be given and how big the dose will be. Vaccination programs may start before the answers are known.