WASHINGTON — In the event of a flu pandemic or a bioterrorism attack, drugs in the future could arrive via door-to-door postal carriers or from the fire station down the street, Health and Human Services Secretary Mike Leavitt said Tuesday.

Leavitt, in an interview with Associated Press reporters and editors, said it's clear the current system of delivering medicines is inadequate in case of a major emergency, and he suggested possible options for the future.

Three pandemics have occurred in the past century, and Leavitt said it was "in some ways an absolute certainty" that a flu pandemic would occur again. "If it happens anywhere, there is risk everywhere," he said.

The government is particularly concerned about bird flu, which since 2004 has sickened 109 people, 55 of whom have died, because people lack immunity to the virus.

Leavitt said the government was looking to stockpile 20 million doses of a bird flu vaccine and another 20 million doses of Tamiflu, an antiviral medication to treat the disease.

The vaccine, in human clinical trials, has created an immune response in those who have taken it, he said. Still to be determined, he said, is how much is necessary to produce a sufficient response.

Leavitt said the government's goal is to have the medicine delivered within 12 hours of a decision.

"We're finding that the distribution systems are not adequate to put medicines in the hands of people fast enough, so we're beginning to look at alternative ways to speed that up," Leavitt said.

"We're looking at having more points of distribution, for example. We're experimenting with having the Postal Service be able to deliver them, because they walk those routes every day."

He said other possibilities included using firehouses as distribution points.

Leavitt said that it would take four to six months to mass produce a vaccine for the avian flu, and that capacity is insufficient to produce both a vaccine for regular flu as well as avian flu. He said officials are trying to determine how to ratchet up production.

Leavitt said he had no intelligence to indicate a pandemic was certain, but the gravity of the threat required that it be treated seriously.

"These are world-changing events when they occur. I believe that we are at a greater risk of a pandemic than we've been for decades," said Leavitt, who has had three recent Oval Office meetings with President Bush to discuss the threat.

Leavitt said the administration was working to develop a domestic surveillance system in hospital emergency rooms that would give public health officials an early warning in the event that the avian flu or any another health threat were to strike.