The US Attorney in New York has subpoenaed information from Chiron, the major flu vaccine supplier for the US, on the unexpected shutdown of a plant in Great Britain. British regulators closed the Liverpool plant last week, freezing shipment of 48 million expected flu shots. The US Centers for Disease Control and Prevention says it's taking every step to get an equitable distribution of available vaccine. The medicine is being sent straight to pediatricians, nursing homes and other places that care for the youngest, oldest and sickest people - those who need it most. But only a fraction of the 22-and-a-half million doses made by Aventis Pasteur can be diverted to areas with the biggest shortages, meaning many high-risk patients will be left out. The FDA is hoping to acquire one-and-a-half million doses from Canada.