The U.S. is making fast progress in preparations for a bird flu pandemic, including measures to close down schools and quarantine the sick, but vaccine supplies remain inadequate, health officials said Sunday.

"We've got a lot of work to do," said Julie Gerberding, director of the national Centers for Disease Control and Prevention, citing "bottlenecks" in vaccine production and the delivery of health care if there's an outbreak.

"We've got to get more and better anti-viral drugs. And we've got to have every single link in our public health system as strong as it can be so it can detect this problem," she said on CBS' "Face the Nation."

A strain of a bird flu that has killed more than 70 people in Asia since it first appeared two years ago has sparked concerns of a super-flu that could kill millions worldwide. Almost all the victims were in close contact with poultry.

While stressing that chances remain slight, health experts have said it could lead to a global pandemic if the bird flu mutates to start spreading easily among people. The U.S., which has not seen any signs of the strain in birds or people, has only enough doses now for 4.3 million people.

Gerberding said some immediate measures to combat the flu in the U.S. and worldwide would include isolating the sick and their immediate contacts. That might entail closing schools, large meetings or otherwise separating the afflicted from the rest of the community.

But she added: "I don't think any of us are thinking about those kinds of Draconian measures to really completely quarantine a community or even quarantine a country."

President Bush last week signed a bill that gives $3.8 billion to prepare for bird flu and liability protections for flu drug manufacturers. The administration is working under the worst-case scenario that as many as 90 million Americans would become ill and 2 million would die in a pandemic, although it would not predict when or if it will happen.

A Congressional Budget Office report released last month estimated the chances of a flu pandemic were less than one-third of 1 percent annually. But it also said a pandemic would wreak havoc on the U.S. economy should it occur, sickening 30 percent of workers in urban areas.

Health and Human Services Secretary Mike Leavitt, appearing on CNN's "Late Edition," praised the money approved by Congress as a good step that will fund one year of preparedness efforts.

Still, he said the U.S. is not ready, saying additional money is needed to ensure there would be enough vaccine supplies for all Americans within six months of an initial outbreak. State and local governments also need to step up efforts, Leavitt said.

"Don't count on Washington, D.C. to manage your pandemic because it will be about your schools, it will be about your parades. You need a plan," Leavitt said, adding that he will meeting with governors in the coming weeks.

Health officials also advised Americans to take the usual precautions in guarding against the flu, such as washing hands frequently and creating a "family disaster plan" such as a week's supply of food in the house. Travelers abroad should avoid unnecessary risks such as eating undercooked or raw chicken.

"Frankly, we're not as prepared as we need to be," Gerberding said. "We're certainly doing more today than we were even two years ago so we're making fast progress. The steps we're taking now really will save lives and will really help us do more to protect people in the future."