Baker noted there was an additional incentive to immunize children, because "children, especially the youngest ones, are such effective spreaders of the flu." By vaccinating children, the spread of flu to unimmunized parents, grandparents and other adults may be minimized.
But Baker noted that it would require widespread immunization for that to happen.
"If you only immunize half the population, you may not see an effect," she said.
One positive sign for Baker and other physicians was an earlier delivery of vaccines this year, with some arriving in August.
"Because we got the vaccine so early, there'll be more time to actually get this done."
Baker said that vaccinations were set to begin Monday, but were delayed a week because of Hurricane Ike.
Manufacturers were also prepared to get vaccines out sooner.
Birke said that Novartis received approval from the Food and Drug Administration to manufacture more of the vaccine at a plant in Rosia, Italy, "to further support our ability to deliver more vaccine earlier in the season."
Organizers also emphasized that people older than 65 should be vaccinated. Despite this recommendation in the past, roughly 70 percent of seniors get immunized each year.
"'Get your flu shot' is still an important message for older Americans," said Kerry Weems, acting administrator of the Centers for Medicare and Medicaid Services.
"Getting these shots costs nothing for people on Medicare," he said. "Free should be cheap enough."
With the increased numbers of people recommended to get the flu shot, higher numbers of immunizations are expected, though last year's vaccine did not protect against influenza as well as it had in the past.
As in years past, strains were chosen in February, based on data about the spread of flu in the Southern Hemisphere and expectations for which strains will predominate in the Northern Hemisphere in the forthcoming season.
"There's a certain amount of science and a certain amount of art to it," said Stephen Morse, an epidemiologist from Columbia University's Mailman School of Public Health, in an interview with ABC News last week.
Dr. Dan Jernigan, deputy director of the CDC's influenza division, said that the virus has matched well in 16 of the last 20 flu seasons.
But last year, two of the three strains of influenza did not match well, so the vaccine only matched the strains going around by 44 percent, as opposed to typical goals of 70 percent to 90 percent.
As a result, all three of the flu strains whose components are included in this year's vaccine are new.
But even fears of a less effective vaccine shouldn't discourage people from getting immunized, said Baker.
"We're not saying it wasn't a good vaccine, we're saying it doesn't match the way it should. We had 44 percent protection ultimately. If you don't get a flu shot, you get none."
"Even though it was a poor match, it's all relative of what you think poor is. Would I like it to be 90 percent? Sure, but I wouldn't like it to be 0 percent."
For his part, Schaffner invokes the French philosopher Voltaire who saw perfection as the enemy of the good.
"We may not have the perfect vaccine, but we have a darn good one," he said. "Partial protection is better than no protection at all."