Ten percent to 20% of Americans get the flu every year. It kills 36,000 Americans a year and sends 200,000 to the hospital.

Although the vaccine supply should be ample this year, with 71 million to 97 million doses, the Centers for Disease Control and Prevention expects some shots to be delayed.

The flu vaccine supply has become a major public health concern. The USA lost nearly half its expected supplies last year after the Food and Drug Administration banned distribution of flu shots from vaccine maker Chiron Corp., whose license was suspended by British regulators because of contamination problems at its plant in England.

The nation's expected flu supply was cut from 100 million doses to 61 million last fall, which caused widespread shortages and long lines at flu clinics.

Chiron announced last month that the Food and Drug Administration has found its British facility "generally acceptable." Although the company expects to produce 18 million to 26 million doses for this flu season, it won't start shipping until the end of September or early October, spokeswoman Alison Marquiss says.

High-Risk Patients

The CDC is not asking doctors to ration the FluMist nasal spray, which uses a live virus instead of the inactivated virus used in flu shots. The sprays can be used by healthy people ages 5 to 49, except for pregnant women.

Julie Gerberding, director of the CDC, urged doctors to delay until Oct. 24 giving flu shots to people at lower risk. That should give high-risk patients the chance to be inoculated first, she said during a briefing at the National Press Club in Washington.

In addition to hurricane survivors, who are more likely to get sick if they have been living in close contact with many other people, doctors should give priority to health workers, people over 65, people with chronic diseases, children ages 6 months to 23 months and people who live with or care for babies under 6 months.

This schedule is designed to allow enough time to protect people who have the most to lose from flu infections, Gerberding says. But it is also meant to allow organizations to schedule vaccine clinics. Health officials say the flu season typically peaks from late December to March.

Kills 36,000 Americans a Year

Managing vaccine supplies is a challenge every year, says Tracy Lieu, an associate professor at Harvard Medical School and member of the CDC's Advisory Committee on Immunization Practices. Last year's warnings about shortages led millions of healthy adults to skip vaccination, and 4.5 million doses went unsold.

"Physicians and nurses feel we send mixed messages -- and we do," Lieu says. "We say, 'Everyone come get your flu shot,' then, 'Wait, there are no flu shots.'"

Ten percent to 20% of Americans get the flu every year, Henry Bernstein, a member of the American Academy of Pediatrics' committee on infectious disease, said at the conference. It kills 36,000 Americans a year and sends 200,000 to the hospital.