Over the ensuing months, cabinet officials got behind the idea. Most of them had governed through the Sept. 11 terror attacks, so events considered unlikely but highly-impactful had a certain resonance.

“There was a realization that it’s no longer fantastical to raise scenarios about planes falling from the sky, or anthrax arriving in the mail,” said Tom Bossert, who worked in the Bush White House and went on to serve as Homeland Security secretary in the Trump administration. “It was not a novel. It was the world we were living.”

According to Bossert, who is now an ABC News consultant, Bush did not just insist on preparation for a pandemic. He was obsessed with it.

“He was completely taken by the reality that that was going to happen,” Bossert said.