The EU"s top drug regulators will fast-track approval for the swine flu vaccine. Countries such as Britain, Greece, France and Sweden may begin using it within weeks so people can be vaccinated before winter. Dr. Keiji Fukuda, the WHO"s flu chief is concerned about potential dangers whereas Leonard Marcus, Harvard University public health expert said not having a vaccine if the virus gets worse could have high consequences. Many experts agree that extensive testing is not required as the only new ingredient will be the swine flu virus.