Up to Half of U.S. Population Could Get Swine Flu

Aug. 24, 2009— -- Thirty to 50 percent of the entire U.S. population could be infected with swine flu this fall and winter, according to a report from the President's Council of Advisors on Science and Technology.

As many as 1.8 million people may end up in the hospital, and 30,000 to 90,000 could die, with a concentration among children and young adults, the presidential panel of the nation's leading scientists said today in outlining what it called a plausible scenario. That's more than twice the annual average of deaths typically associated with the seasonal flu, and those occur mainly in people older than 65.

"We're going to have people hospitalized and we will, unfortunately, have more deaths," said Health and Human Services Secretary Kathleen Sebelius.

The report says this swine flu is a "serious threat to our nation and the world." Because it's a new strain of the flu, people do not have a built-in immunity.

Many swine flu experts view the numbers as reasonable.

"This looks like reasonable estimates and consistent with how pandemic viruses act," said Greg Poland of the Mayo Clinic in Rochester, Minn.

"My reaction is that the numbers, although scary, may be quite accurate," said Joan Nichols of the University of Texas, Galveston.

But others are more skeptical, saying these numbers seem to be a worst-case scenario.

"These speculations have no firm scientific basis, only a historical precedent from almost a 100 years ago and epidemiologic data from recent circulating virus patterns," said UCLA's Peter Katona. "Viruses have a mind of their own, and we will have to just see what happens."

Marc Lipsitch of the Harvard School of Public Health emphasized that the numbers are not predictions, but scenarios.

"It is not possible to predict with certainty how many cases or deaths will occur from this flu," he said.

With 20 weeks left to go in the year, the 2008-09 flu season has 17 more pediatric deaths than the previous year, and there have been at least 7,963 hospitalizations and 522 deaths from swine flu. The CDC says 75 percent of the hospitalizations are in those under 49, and 60 percent of the deaths are also in those under age 49.

The numbers, while higher than usual, are still low. But if the virus spreads throughout the population, it could be far more problematic.