There is no vaccine available to prevent the new swine flu. However, there are antiflu drugs that do work once someone is sick.

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 step -- creating what's called seed stock of the virus that manufacturers would use.