Nearly all of the first 6 million doses of swine flu vaccine are the FluMist nasal spray vaccine. By mid-October, the government plans to deliver some 45 million doses -- including more traditional flu shots -- apportioned to states based on population.
Swine Flu Outbreak: Get the Facts
Get the latest swine flu facts and information from WebMD, the CDC and other
public health agencies.
"We have a vaccine and it is likely to be effective after a single dose for those over 10, and it is going to be rolling into doctors' offices and clinics," Frieden said at a news conference.
Because the FluMist vaccine cannot be given to pregnant women, kids under age 2, or to those with underlying health problems, the first vaccine doses will go to health care workers and to people caring for or living with infants under 6 months of age.
As flu shots arrive, priority vaccinations will go to pregnant women and to school-age kids. Different states are emphasizing different kinds of programs. Frieden said school-based vaccination programs are especially important.
"We know many kids get sick from flu, and not only is that a problem for them, but they end up spreading flu widely in the community," Frieden said. "So if you protect kids, you probably end up protecting the community as well."
Although the vaccine is right on schedule, it's arriving at least two weeks after the flu pandemic. As of Sept. 19, H1N1 swine flu was widespread in 26 states. Doctors in nine of the 10 U.S. surveillance regions reported elevated rates of flu-like illness -- and virtually all proven cases of flu have been swine flu.
Will it be too late for people to get vaccinated? No, Frieden said. There's no way to tell whether there will be new waves of pandemic flu. And even if 10% of the population gets the flu -- as happened in New York City last spring -- that means 90% of the population remains vulnerable until vaccinated.
Swine Flu Vaccine Distribution 'Bumpy' at First
The CDC is working to ensure equitable vaccine delivery across the nation. But Frieden said some states are better prepared than others to start vaccinating their residents once the federal government delivers the swine flu vaccine to them.