If past trends hold, the misery will spread widely over the next six weeks or so, keeping millions of Americans out of school and off the job - including those in nursing homes and hospitals. Some health-care employees will try to work through their illness, putting the most vulnerable at risk.
With tens of thousands of flu-related deaths a year, medical institutions are fighting an uphill battle to persuade workers to get shots.
Some use carrots (win a free iPod!). A few use big sticks (no shot, no job). Penn added "Baby Be Wise - Immunize!," the music video created by an irrepressible nurse and an ER volunteer.
"It's wonderful in my opinion - an engaging and fun way to garner interest on a serious topic while making people feel part of a team," said Gregory A. Poland, director of the Mayo Clinic's vaccine-research group, who saw the video on YouTube.
Nationwide, about 46 percent of health-care workers got flu shots in 2007 - more than in many other countries and an increase over past years, but well below expectations. (HUP's numbers were just a little higher.)
Some doctors say they are too busy or don't think they'll get sick.
Administrative staff might not realize that the hand they sneezed on touched a file that was opened by a nurse who took a cup to a patient, with the virus hitching a ride.
In Philadelphia, all the nursing homes that responded to a survey last year said they vaccinated workers for free, nearly all held educational sessions, and more than a fifth offered incentives to act. Still, just 37 percent of direct-care workers agreed to a shot.
