President Bush (search) gave vaccine makers a pep talk Friday about ramping up production to counter the threat of bird flu.

Amid fears a pandemic could kill millions, the president sat down with the chiefs of six manufacturing companies — as well as federal health officials.

Afterward, Health and Human Services Secretary Michael Leavitt (search) told reporters that more vaccine capacity is urgently needed. Right now, just one U.S. manufacter is ready to mass produce a vaccine that's shown promise.

But Leavitt said greater vaccine capacity's needed even if bird flu weren't such a threat.