The panel also said those first vaccinated should include parents and other caregivers of infants; non-elderly adults who have high-risk medical conditions; and young adults ages 19 to 24.
The Advisory Committee on Immunization Practices voted to set vaccination priorities for those groups Wednesday during a meeting in Atlanta. The panel's recommendations are usually adopted by federal health officials.
The recommendations are designed to address potential limits in vaccine availability this fall if there is heavy demand and limited supplies.
The government estimates that about 120 million swine flu vaccine doses will be available to the public by late October. Roughly 160 million people are in the priority groups considered most vulnerable to infection or most at risk for severe disease.
Although the number recommended to get doses exceeds the projected supply, health officials don't think everyone will run out and get vaccinated. Traditionally, less than half of the people recommended to get seasonalget them. Only about 15 percent of pregnant women get seasonal flu vaccinations.
If there is ample vaccine, vaccinations also would be recommended for all non-elderly adults, the panel also voted. And if there's still plenty of vaccine, the swine flu shots and spray doses should be offered to people 65 and older. Fewer illnesses have been reported in the elderly, who appear to have higher levels of immunity to the virus, health experts say.
However, the elderly should be pushed to get shots against seasonal flu, which is a significant health risk to older adults.
Panel members say they hope swine flu vaccinations will be opened up quickly. "The only sin is vaccine left in the refrigerator," said Dr. William Schaffner, a Vanderbilt University flu expert, in a comment to the panel.
The panel also said if vaccine is scarce, the government could require that a much tighter group be at the front of the vaccination line, numbering about 40 million. That would include pregnant women and household contacts of small children, just like in the general priority recommendation. But the others would be children ages 6 months through 4 years, children with chronic medical conditions and only health care and emergency services workers who have direct contact with patients.
It's a worst-case scenario that officials aren't expecting, but they wanted to have a plan for it just in case, said officials with the U.S. Centers for Disease Control and Prevention, the federal agency that reviews the panel's recommendations.
The range of recommendations reflects how hard it is to plan for swine flu, officials said. Some health officials have compared the exercise to predicting a hurricane. The storm — or virus — is itself unpredictable; it could grow more dangerous or suddenly weaken. The availability of lifesaving supplies or vaccine can also affect survival.
"It's better to prepare and have the storm fizzle than to be sitting there with no way off the island when the tsunami rolls in," said Kristine Sheedy, a CDC communications specialist.
Variables with the swine flu virus can range from whether it mutates into a form that is more deadly, spreads more efficiently, or is better at fighting off current.
Variables with the vaccine include potential production problems. Production of the vaccine will be a prodigious feat: The government has already purchased 195 million doses for the coming fall and winter, which far eclipses the 125 million or so doses generally produced for seasonal flu vaccine.
Four vaccine manufacturers are wrapping up seasonal flu vaccine production and have begun production of swine flu vaccine. But another company, Sanofi Pasteur, has been more delayed and may not finish seasonal vaccine production until September, a company spokeswoman said. Sanofi is among the largest producers of flu vaccine, so those delays could have a significant ripple effect.
Packaging, distribution and other steps can take a month or more. For those reasons, the government's best guess at the moment is 40 million doses will be available in September and 120 million by around mid-October.
Health officials are pushing for the work to done quickly. There are also clinical trials taking place over the next few months to check the vaccine's safety and effectiveness, but it's possible the government will begin a public vaccination campaign before that work is complete, said Dr. Anne Schuchat, who oversees the CDC's flu vaccination programs.
Why the rush? Vaccines work when given to a patient before they're exposed to the vaccine-targeting virus, and cases may explode not long after kids get back in school, CDC officials said.
Another reason for not waiting for testing data: Health officials are thinking of the swine flu vaccine as a variation of seasonal flu vaccine, which comes out annually and does not undergo the kind of safety and effectiveness testing that new drugs and other new vaccines do.
First identified in April, swine flu has likely infected more than 1 million Americans, thebelieves, with many of those suffering mild cases never reported. There have been 302 deaths and nearly 44,000 laboratory-identified cases, according to CDC numbers released last week.
It's not clear whether the virus in its current form is much worse than seasonal flu in terms of overall threat to the U.S. population, but it is causing more severe illness in some younger adults and children. It has a dangerous genetic characteristic that allows it to infect the lower lungs, whereas seasonal flu tends to infect the upper respiratory tract, CDC officials said.