Swine flu poses "serious health threat" to US, could kill 90k Americans: White House

The report concludes that the 2009-H1N1 flu is unlikely to resemble the deadly flu pandemic of 1918-19, but "the issue is not that the virus is more deadly than other flu strains, but rather that it is likely to infect more people than usual because it is a new strain against which few people have immunity," the White House said.

The advisors estimate that 40 to 60 percent of the U.S. population could contract the virus this fall and winter, compared with the average of 5 to 20 who get the seasonal flu.

"It is not possible to predict how the 2009-H1N1 influenza virus or the upcoming influenza season will play out, but it is best that we plan and prepare for resurgence," Homeland Security Secretary Janet Napolitano said in a prepared statement.

"As the nation prepares for what could be a challenging fall, it is crucial that our public health decisions are informed by the very best scientific and technological information," said John P. Holdren, Assistant to the President for Science and Technology and a co-chair of PCAST.

 "The Department of Health and Human Services, including the Centers for Disease Control and Prevention, National Institutes of Health, and Food and Drug Administration, has already made some important progress on the recommendations found in the PCAST subcommittee report and we plan to adopt others to ensure we are doing everything we can to keep Americans healthy and safe," Health and Human Services Secretary Kathleen Sebelius said.