On Kris Ehresmann's 2009 calendar, April 23 is marked with two events: "Get haircut. Pandemic begins."

That was the day Ehresmann, head of Minnesota's state vaccine program, learned that the nation's first cases of H1N1 flu had surfaced in California and Texas.

As she headed out the door that day, all she can remember thinking is: "Oh please, let this not be what I think it is."

Now, eight months later she has the answer. The 2009 flu pandemic was not the disaster public health authorities had planned for -- one that, like the 1918 Spanish flu, would kill tens of millions around the world.

But it's been pretty bad, with hundreds of patients hospitalized in Minnesota and a tragic death toll among the state's children. It's also held enough surprises to keep public health experts guessing all the way.

"The virus didn't read the playbook," Ehresmann said in an interview last week.

For now, the H1N1 outbreak is in a lull, but it may return before the winter is out. Looking back on the year, experts say they've learned some lessons from the Great Flu Pandemic of 2009. One: Expect the unexpected. Two: Don't over-promise, especially when it's a vaccine. Three: Worst-case scenario planning pays off.

"When you don't know what's in front of you, you really have an obligation to prepare for the worst," said Patsy Stinchfield, director of infectious disease at Children's Hospitals and Clinics of Minnesota. "And if the worst doesn't happen, we're all thankful."

The virus debuts

In Minnesota, the first case of what was then known as swine flu appeared April 30 at a middle school in Cold Spring. Reporters and disease experts from the Minnesota Department of Health descended on the small town. Two schools and a senior citizens center were closed. Gov. Tim Pawlenty ordered the state plane to ferry the specimen to the federal Centers for Disease Control and Prevention (CDC) in Atlanta for testing.

By the time the outbreak's first wave ended, two months later, experts knew H1N1 wasn't likely to be as bad as the virulent 1918 Spanish flu. But for reasons that are still not entirely clear, it was more dangerous to children, young adults and pregnant women than it was to the elderly.

The CDC rushed to commission a vaccine, hoping it would be ready for fall, when they knew H1N1 would return with a vengeance. But vaccine manufacturing processes are old, slow and unpredictable. Even if everything went right, it would take six months.

In the absence of a vaccine, Ehresmann and her colleagues knew Minnesota needed stopgap measures, and their only tool was to encourage the public to contain the virus itself. The "wash your hands, cover your cough" message became a public health mantra.

Just as expected, the outbreak resumed as soon as school started. By mid-October, school absences were mounting, hundreds of people were landing in the hospital -- and as authorities feared, the state's health care system was taxed to the limits.

Nowhere was the outbreak more dramatic than at Twin Cities' children's hospitals.

"We were ground zero," said Stinchfield at Children's. In all, 328 children were hospitalized there with H1N1, 50 of them in intensive care. So many kids poured into Children's emergency rooms -- a record 400 a day at the peak in October -- that the staff had to convert a day clinic into an overflow ER.

It may not have been the pandemic everyone feared, Stinchfield said, but it was bad enough. "I hope that the words 'just' and 'flu' are not in the same sentence ever again," she said.

Most children recovered within a few days, but many needed chest tubes and ventilators; at least one child was hospitalized for two months, and some were left with permanent brain damage.

Meanwhile, a surprising number of healthy, younger adults were devastated by H1N1, including Krystal Alwin, 28, who now lives in east St. Paul. She got sick on a Friday in October. Because she didn't have health insurance, she waited until Monday to see her doctor. Her clinic immediately called an ambulance -- then asked if she had a living will.

"I felt sicker after hearing that," she said last week.

Alwin was on a ventilator and in a coma for two weeks at United Hospital in St. Paul before she woke up in the intensive care unit. She's recovering now and looking for a job. But she lies awake nights worrying about how she will pay off her $300,000 hospital bill.

"I should never have waited," she said. "If I had [gone] in on Friday I would have been fine."

Vaccine delays

A vaccine might have helped patients like Alwin, too. But unexpected manufacturing problems turned the supply into a trickle and confounded the optimistic promises of federal health officials.

Clinics were flooded with calls from patients seeking vaccine. At day care centers and school events, mothers exchanged tips on where to find it. When Park Nicollet Clinic announced it had a limited supply, its switchboard crashed.

"The pressures to say we've got the vaccine ... made us paint a much more rosy picture than was actually [true]," said Stinchfield. If, instead, federal health officials had warned it wouldn't be widely available until January, they would have looked like heroes when it started arriving in October.

That, Stinchfield said, "was probably the only thing I think people would want to take back and do over." All the experts agree that one of the major lessons learned last year is that it's time to develop a better, faster way to make flu vaccine.

Once it became clear that initially there would be a shortage, Minnesota, in contrast to other states, devised a lottery system to distribute the vaccine to local public health agencies and clinics. Officials started with those who took care of the sickest children and gradually expanded to others as supplies increased.

At the height of the outbreak in October and November, state health officials took heat from many who wanted the vaccine but couldn't get it.

Ehresmann said she has no regrets because the plan worked. Vaccine went to the vulnerable first. There was no outcry here as there was in New York, when Wall Street firms gave shots to employees.

But, Ehresmann says, she would give federal and state public health agencies a grade of "D" in managing public expectations. "We have to talk more about the reality of shortages and what it means," she said.

So how bad was the Great Pandemic of 2009?

Across the country so far there have been some 16 million more cases than in the average seasonal flu season and 13,000 more hospitalizations, said Mike Osterholm, an infectious disease expert at the University of Minnesota. There have been nearly 10,000 deaths, far fewer than in a typical flu season -- but the vast majority were in people younger than 65, he said.

And it's not over until it's over.

"We could have a lot of illness yet to come," he said.

Josephine Marcotty • 612-673-7394 Maura Lerner • 612-673-7384