"I think that in the post-pandemic age, after 2009-10, that we" - the public, clinicians, hospitals - "are more aware of influenza," said Neil Fishman, an infectious diseases physician at the Hospital of the University of Pennsylvania.
"Prior to H1N1, people were just more likely to stay home," he said. Now they go to the doctor. Hospitals test for the flu more, too. "There's increased awareness that influenza can be a fatal illness," Fishman said.
Flu varies tremendously from season to season and place to place. It arrived early everywhere this year, often coinciding with several other viruses, and has been described as more severe than usual in some parts of the country, although not locally so far.
Reports of high, even record, volumes at some emergency departments, meanwhile, reflect more than the current flu. More Americans have been seeking care at ERs in recent years for reasons ranging from a lack of insurance that worsened their conditions to an inability to see primary-care doctors during office hours.
"Every year we hit a new high," said Joe Zorc, an attending emergency physician at Children's Hospital of Philadelphia, which has logged several near-record days over the last month.
Patient visits to emergency departments in Southeastern Pennsylvania increased more than 30 percent between 2001 and 2011, according to state Department of Health data.
The number of ERs decreased from 48 to 38 over that same period. Although some expanded, patients are now concentrated in fewer locations.
"We have so downsized health care that we can overwhelm health care," said Michael T. Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota. To reduce costs, hospitals have "cut out any kind of expandable capacity," he said.
"Hospitals have been challenged to meet a very rapidly changing health-care environment," added Curt Schroder, head of the Delaware Valley Healthcare Council, which represents hospitals. He said they were managing fine with the flu.
Economic woes add to the pressure on hospitals, and might help spread disease.
"People are afraid that if they miss work to stay home with their child, they will be out of a job," said Esther K. Chung, a pediatrician in Center City. So sick children may be sent to school, spreading infection.
"I'm hearing that more this year than in previous years," said Chung, who added that the economy also may be forcing some people in her diverse practice to move in with relatives, perhaps creating conditions for virus transmission through closer contact.
City Health Commissioner Donald F. Schwarz last week mentioned yet another factor that could have affected the flu this year: Christmas.
While early flu seasons tend to be bad ones, this time the virus happened to arrive in the Philadelphia region just before many people left work and school for a week or two to celebrate the holidays. And that, Schwarz said, "is terrific for the spread of influenza."
There clearly is more interest in the flu this year, at least now that it's here.
"People got complacent" about immunization after a couple of light flu seasons, said Sue Kressly, a pediatrician in Bucks County. But "since this has been hitting the news and people are getting sick, people have been calling."
Most private physicians must order vaccine from manufacturers months before flu season, based on estimates of demand. Now the need is greater than Kressly can meet. Her Warrington practice has run out of vaccine formulations for ages 3 and up.
"I think people have forgotten a little bit about what the flu can do to a community," said John Russell, director of the family medicine residency program at Abington Memorial Hospital. "It's like going a couple of seasons without snow, and then it snows again and people go, 'My God!' "
Contact Don Sapatkin at 215-854-2617 or firstname.lastname@example.org.