Praxis, which makes vaccines, said last week that one or more companies had expressed interest in acquiring it.

Each new strain can be cultivated in hens' eggs to make vaccines.

"You couldn't have been the only guy using monkeys, or even monkey blood, to make vaccines in 1940."

Scientists have tried to make such vaccines for decades, without success.

At the same time, however, prices aren't high enough to persuade drug companies to make existing vaccines and find new ones.

But in the past, few of the major pharmaceutical companies have been interested in making vaccines for the government.

The government cannot force companies to make vaccines, however.

He acknowledged that the administration had failed to persuade more manufacturers to make vaccines in recent years.

A number of drug makers had stopped making vaccines rather than face costly litigation.

That is one reason the drug companies until now have been reluctant to make vaccines for the Pentagon.