"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 has not been more deadly than the flu strains seen every year during the cold months: many people have only mild illness. Also, close genetic tracking of the new virus as it circled the globe during the past five months so far has shown no sign that it is 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 should suddenly worsen or vaccination plans should fall 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 per cent to half the 300 million Americans could catch what doctors call the "2009 H1N1" flu; the extrapolation said death possibilities ranged from 30,000 to 90,000. In a regular flu season, up to 20 per cent 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 will not speculate, finding a numbers game pointless as it tries to balance getting a largely complacent public to listen to its flu instructions without exaggerating 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.
CBS News medical correspondent Dr. Jennifer Ashton reports that the Obama administration is pushing health officials to see if the immunization program can be accelerated.
Under the current plans, people who get their first shots in mid-October wouldn't actually be fully immunized until around Thanksgiving, after booster shots, reports Ashton. She calls the government's goal of immunizing some 195 million Americans by the end of the year, considering manufacturers' capacity to produce the drugs, "definitely ambitious".
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 during the summer, infecting children at camps during midyear schools in particular. Already clusters of illnesses are being reported at some schools and colleges around the country.