"Everything we've seen in the U.S. and everything we've seen around the world suggests we won't see that kind of number if the virus doesn't change," Dr. Thomas Frieden, head of the Centers for Disease Control and Prevention, said in a C-SPAN interview taped Wednesday.

While the swine flu seems quite easy to catch, it so far hasn't been more deadly than the flu strains seen every fall and winter - many people have only mild illness. And close genetic tracking of the new virus as it circled the globe over the last five months so far has shown no sign that it's mutating to become more virulent.

Still, the CDC has been preparing for a worst-case flu season as a precaution - in July working from an estimate slightly more grim than one that made headlines this week - to make sure that if the virus suddenly worsened or vaccination plans fell through, health authorities would know how to react.

On Monday the White House released a report from a group of presidential advisers that included a scenario where anywhere from 30 percent to half of the population could catch what doctors call the "2009 H1N1" flu, and death possibilities ranged from 30,000 to 90,000. In a regular flu season, up to 20 percent of the population is infected and 36,000 die.

"We don't think that's the most likely scenario," CDC flu specialist Dr. Anne Schuchat said of the presidential advisers' high-end tally.

What's really expected this year? CDC won't speculate, finding a numbers game pointless as it tries to balance getting a largely complacent public to listen to its flu instructions without hyping the threat.

Along with how the virus itself continues to act, the ultimate toll depends on such things as vaccinations beginning as planned - currently set for mid-October - and whether the people who need them most get them. CDC also is working to help hospitals keep the not-so-sick from crowding emergency rooms and to properly target anti-flu drugs to the most vulnerable.

What is likely: A busy flu season that starts earlier than usual, Schuchat told The Associated Press. This new H1N1 strain never went away over the summer, infecting children at summer camps in particular. Already clusters of illnesses are being reported at some schools and colleges around the country,

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