Hospitals could modify patient rules -- for example, requiring them to give less information during a hectic time -- to quicken access to treatment, with government approval.
The declaration, which the White House announced Saturday, allows HHS in some cases to let hospitals relocate emergency rooms offsite to reduce flu-related burdens and to protect noninfected patients.
Administration officials said the declaration was a pre-emptive move designed to make decisions easier when they need to be made. Officials said this was not in response to any single development on an outbreak that has lasted months and has killed more than 1,000 people in the United States.
It was the second of two steps needed to give Sebelius extraordinary powers during a crisis. On April 26, the administration declared swine flu a public health emergency, allowing the shipment of roughly 12 million doses of flu-fighting medications from a federal stockpile to states in case they eventually needed them. At the time, there were 20 confirmed cases in the U.S. of people recovering easily. There was no vaccine against swine flu, but the CDC had taken the initial step necessary for producing one.
"As a nation, we have prepared at all levels of government, and as individuals and communities, taking unprecedented steps to counter the emerging pandemic," Obama wrote in the declaration.
He said the pandemic keeps evolving, the rates of illness are rising rapidly in many areas and there's a potential "to overburden health care resources."
Because of vaccine production delays, the government has backed off initial, optimistic estimates that as many as 120 million doses would be available by mid-October. As of Wednesday, only 11 million doses had been shipped to health departments, doctor's offices and other providers, according to the Centers for Disease Control and Prevention officials said.
The government now hopes to have about 50 million doses of swine flu vaccine out by mid-November and 150 million in December.
The flu virus has to be grown in chicken eggs, and the yield hasn't been as high as was initially hoped, officials explained.
Swine flu is more widespread now than it's ever been. Health authorities say almost 100 children have died from the flu, known as H1N1, and 46 states now have widespread flu activity.
Worldwide, more than 5,000 people have reportedly died from swine flu since it emerged this year and developed into a global epidemic, the World Health Organization said Friday. Since most countries have stopped counting individual swine flu cases, the figure is considered an underestimate.