(USA TODAY) -- His parents had to stand in line for 4 hours at a flu shot clinic earlier this month, but finally Rhys MacMillan, 7 months old, got his first flu shot.

Now, whether he'll get the second shot he needs as a booster is "iffy," says his mother, Leigh MacMillan of Nashville.

"If vaccine is still available in a month, we'll have it," she says. Her pediatrician, who had none to offer, urged her to find at least one dose for Rhys. "She said one is better than none," MacMillan says. But her older son, Cade, almost 3, and his parents will have to skip a vaccine this year.

Initially, health officials said the shortage would not affect the supply for babies, because Chiron's vaccine, unavailable now because the company's license was suspended, was never intended for children under age 4. Aventis Pasteur's vaccine is licensed for everyone over the age of 6 months. Babies get half an adult dose. Aventis produced 3 million pre-filled syringes in baby doses, but the bulk of the 60 million doses the company is making this year is in multidose vials containing enough vaccine for 10 adults or 20 babies.

Because shots are targeted to anyone in a high-risk group, babies, seniors and those with chronic health conditions are drawing from the same limited supply, says pediatrician Kathy Poehling of Vanderbilt University Medical Center.

Federal health officials have stockpiled 4 million doses of flu vaccine, half of it earmarked for babies or high-risk children, and say those doses will be parceled out to areas of greatest need.

Meanwhile, pediatrician Joseph Bocchini of Shreveport, La., a spokesman for the American Academy of Pediatrics, says doctors are trying to find vaccine for those who need it most, and hoping more will be available later in the season.

Meanwhile, the doctors' prescription:

• Avoid infection. Flu germs live on surfaces, so kids should be taught to wash their hands frequently and avoid putting hands to eyes, nose or mouth. When coughing or sneezing, use tissues. Keep kids away from sick people and keep them home when sick.
• Call the doctor at the first sign of flu -- a sudden high fever, often with chills and muscle aches. Antiviral medications can reduce the severity, but need to be started in the first 48 hours of symptoms.

MacMillan has heard the advice, but "it's really difficult with a 3-year-old in day care."

If Cade or his parents come down with flu, she says, they'll do their best to weather it. "It's more of a worry of juggling all the things you have to juggle in life, keeping all those things in balance," she says. "That's the concern, that little gnawing thing of 'oh, great, what's this going to do to us this winter.' "

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