If all goes well this year, the nation's supply of annual flu vaccine should be the largest on record, so health authorities say they'll urge that more Americans - especially young children and health care workers - get flu shots next fall.
Authorities say they also want 90 percent of Americans 65 and older to receive annual flu shots by 2010, up from 65 percent today. And there may be a recommendation next month that the nation move toward universal flu vaccination.
Unlike a bird flu pandemic, which remains just a possibility, "there will be influenza annually - real, traditional seasonal influenza that on average kills 36,000 Americans each year and results in 200,000 hospitalizations," Dr. William Schaffner of the National Foundation for Infectious Diseases said at a gathering of flu experts yesterday.
"And vaccination remains the single most effective preventive measure," he said.
The United States got off relatively easily during the 2005-2006 flu season, which was milder and less disruptive than the previous two seasons, according to the U.S. Centers for Disease Control and Prevention.
Even so, many shot-seekers had difficulty finding vaccine during the fall - the result of an unusually large response to the flu shot campaign. Supplies became more plentiful during the winter, but by that time many people had given up the search.
In Maryland, "it looks like this flu season was relatively mild," said Greg Reed, program manager for the Maryland Center for Immunization, part of the state Department of Health and Mental Hygiene.
The seasonal flu is not a reportable disease, so there are no comprehensive counts. But a network of "sentinel" physicians does send viral samples to the state for laboratory testing each year, and that provides a rough indicator of year-to-year trends.
Reed said there have been 854 laboratory-confirmed flu cases since October, down from 2,395 during the same period last year.
In recent years about 80 million doses of annual flu vaccine have been produced for the U.S. market. The number fell to about 60 million in 2004 when one vaccine maker, Chiron Corp., was forced to shut down because of a production problem.
That led to widespread shortages, long lines and forgone immunizations during the autumn, at the peak of annual demand.
Flu experts who spoke yesterday at the National Press Club in Washington said if there are no manufacturing glitches, there should be at least 100 million doses, and perhaps 120 million, this year.
"It's a bumper crop, more influenza vaccine than has ever been produced in the U.S. before," said Dr. Ray Strikas of the National Vaccine Program Office, part of the U.S. Department of Health and Human Services. "We've begun to talk about how to promote vaccine, rather than how to ration vaccine."
One reason for the brighter outlook is a $7.2 billion investment of federal money in vaccine development and production, driven in part by fears of an avian flu pandemic and by post-Sept. 11 concern about bioterrorism.
Vaccine production may get a boost this year from the possible addition of a new manufacturer to the four licensed by the Food and Drug Administration. The newcomer, a GlaxoSmithKline subsidiary, could produce 15 million to 20 million additional doses.
More encouragement comes the CDC's Advisory Committee on Immunization Practices.
In February, the committee recognized the key role of children in spreading the flu. It recommended expansion of priority vaccination to include children 6 months through 5 years, instead of just 6 months to 2 years. Those younger than 6 months are considered too young for the vaccine.
Next month, the ACIP will consider recommending two doses of flu vaccine for children ages 6 months to 9 years, instead of one, and the panel might propose a move toward universal flu vaccination, according to the CDC.
Health authorities are already urging more health care workers to get flu shots.
"With vaccination there is less chance of health care workers both contracting and transferring [flu] to susceptible patients," said Dr. Ardis D. Hoven, a member of the board of trustees at the American Medical Association. "Yet only 40 percent of health care workers get immunized."
Still more stimulus for vaccine makers and care providers could come from Medicare's decision to increase reimbursement for flu shots from $8 to $18 per dose.
Increased vaccine production would reverse the trend of recent years, in which vaccine makers have left the flu vaccine market because of low and inconsistent demand and skimpy profits.
"I think the manufacturers believe that the market for influenza vaccine is going to grow, that we are going to do a better job of immunizing people in the target groups," Schaffner said.
Increased supplies should help ease the frustration many people have had trying to get flu shots. But some supply-and-demand problems still need to be addressed, officials said.
Public demand for flu vaccine typically peaks in October, while production and shipment are not complete until January. Not surprisingly, not everyone who seeks a shot in the fall can find one. "One of the things we're hoping to do is extend the vaccination season beyond November," said Christine Layton of RTI International, a nonprofit research firm that has studied vaccine issues.
The 2005-2006 flu season didn't peak until March, and the previous season peaked in February. "The benefits from flu vaccine remain, even when you're vaccinated in January and beyond," Hoven said.