The acting head of the Centers for Disease Control and Prevention says the government is still deciding whether to order that a swine flu vaccine be produced.
Dr. Richard Besser says it's not an easy decision, because vaccine manufacture takes a long time and would interrupt ongoing work to create next winter's regular flu shot.
But if a vaccine eventually is ordered, the CDC already has taken a key preliminary stepcreating what's called seed stock of the virus that manufacturers would use.