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."