He noted that in terms of running their operation, the executives should consider that they might be among the stricken and should consider equipping workers with handheld remote devices for work outside the office as well as purchasing Tamiflu anti-flu medication.

The United States, he said, has only eight million doses of medication specifically designed to fight the current bird flu virus threat, clinically known as H5MI, and it requires two doses per person.

Once the flu arrives, Mr. Thompson advised, the attack would ebb and flow, lasting 12-to-15 months.

He said the nation is hampered because it uses an "arcane" method to produce vaccine, a process involving inoculation of chicken eggs. As health secretary, he said he asked for a $2.5 billion appropriation to improve vaccine production methods. However, even with the cash in hand, it would still take five years to get adequate production levels.

Mr. Thompson also said the nation needs a strong public health system equipped to deal with bio-terrorism, which "if we don't have, your businesses will be hurt."

After the Sept. 11 terror attacks, Mr. Thompson observed that "it was clear we had let public health wither on the vine" and the nation learned its limitations in dealing with threats like anthrax spores, smallpox and SARS from Asia.

Although $15 billion has been appropriated to meet these threats, and progress has been made, Mr. Thompson said "a lot needs to be done," particularly in the area of food shipment inspection, noting that less than 5 percent of the food that comes in from Asia is inspected.

"We are at war. We must remain vigilant...We must not be lulled," he warned.