The first step was to send batches of the virus to a handful of vaccine experts like Bucher. As soon as she received her supply of 2009 H1N1, she got to work on creating a “seed stock” of modified viruses that could be used to produce hundreds of millions of vaccine doses. Manufacturers for the most part still make flu vaccines the way they did in World War II: in chicken eggs. Bucher had to transform the viruses, which grow very well in human airways, so that they would grow very well in eggs.

Bucher and her colleagues created a new seed stock using a method more than four decades old, which she has been refining in recent years, as she has helped prepare each year’s seasonal flu vaccine. She and her colleagues drilled tiny holes into the eggs and injected the 2009 H1N1 virus, along with another flu strain that grows well in eggs. The two viruses made copies of themselves in the eggs, and sometimes their genes mixed together, producing hybrids. Bucher’s team harvested the viruses from the eggs and plucked out the best-growing hybrids, reinserting the lines into new eggs. Before long, the team had produced a hybrid that could be used to inoculate people against 2009 H1N1—and could produce 32 times more virus in eggs than the strain Bucher had received in the mail. “We got this thing ready in three weeks,” Bucher told me recently, with the pride of a viral gardener. “It worked beautifully.”

But it was not until October that the first 2009 H1N1 vaccines started trickling into clinics and hospitals. Six to eight months from isolating a new flu virus to putting shots in arms is a typical schedule for a flu vaccine. Unfortunately, the virus didn’t get the memo. Cases of 2009 H1N1 were already skyrocketing in the United States—but the vaccine supply was less than half the projected amount. Many of the people clamoring for the vaccine couldn’t get it.

Bucher’s daughter was one of them. “She had a baby at the end of September, and that meant she was really at risk,” Bucher told me. “My daughter went to a vaccine site on the Upper East Side. The line went for blocks. And then she went home.” Bucher was frustrated to no end that her own daughter couldn’t get the vaccine she had created six months earlier, fewer than 30 miles away.

“I thought, This is really depressing,” says Bucher.

Fortunately, her daughter survived the pandemic, and 2009 H1N1 turned out to be a bullet dodged. In 2012, a CDC-led team of epidemiologists reviewed health records and estimated that only 284,400 people died of H1N1-related complications worldwide in the first 12 months of its wide circulation. “Only 284,400 deaths” may sound like a grotesque downplaying of a huge loss of life, until you consider that the 1918 pandemic killed, according to some estimates, nearly 200 times as many people.