SEATTLE -- Hospitals from Seattle to Everett are taking new measures to try and stop this year's flu outbreak, which some health authorities called one of the worst they've seen.

Micki's Flu Q&A Prevention Flu Shots Treating Flu Protect Kids Chicken Soup? Flu Shots: True Or False? Cold Or Flu? Map: Flu Trends CDC Flu Site Local Flu Shot Info: King County Local Flu Shot Info: Snohomish County Find A Flu Shot Clinic

Some hospitals will begin asking people who are coughing or sneezing to put on surgical masks this week, our news partner, The Herald Of Snohomish County reported.

Patients arriving at Providence Everett Medical Center's emergency department will be handed a letter explaining the request.

The University of Washington Medical Center in Seattle is putting up signs asking anyone with respiratory symptoms, even if they're not patients, to put on masks to prevent the spread of flu viruses, the newspaper reported.

Meanwhile, health officials are asking physicians to give priority for the increasingly scarce flu vaccine to children and adults at high risk for complications.

Federal health officials are considering buying vaccine from other countries and sending more vaccine to states hardest hit by the shortage, including Washington.

Last week, the nation's main flu shot makers said they had sent all of this year's flu shots -- about 80 million doses -- to doctors and clinics.

"We wish manufacturers made more vaccine this year," said Dr. Julie Gerberding, director of the Centers for Disease Control and Prevention. Federal officials are checking to see if there is any extra flu vaccine in Europe that could be used in the United States, she said.

In another development, some experts said this year's flu vaccine may not do as much to protect you against the virus as in past years.

Even in the best of years, the flu shot is not foolproof. Ordinarily it is between 70 percent and 90 percent effective in healthy young adults and somewhat less effective in the elderly.

The last time the vaccine missed the mark was in 1997, when a strain called A-Sydney appeared that was significantly different from the strain included in the flu shot. Doctors are still uncertain about how much good the shot did that season, although the CDC estimates it was 30 percent to 50 percent protective.

Scientists say this year's mismatch does not seem to be as great as it was six years ago, but they cannot say with certainty how well the flu shot will work, or even whether it will.

"With a vaccine with a less optimal match, you have to say it might not work at all," said Dr. Scott Harper, a CDC epidemiologist. "That's very unlikely. Probably it will not be 90 percent effective. But we just have no good sense of how it will work in humans. Biology is messy."