Flu season is bad enough, but this year a contamination problem at the English factory where nearly 50 percent of U.S. flu vaccine is produced will limit availability of the shots. Here's what's behind the shortage—and what your family can do about it.

Who should get the shot this year?
Priority will go to young children (6 to 23 months), the elderly, pregnant women, health-care workers and people who suffer from chronic illness. More than 35,000 people, mostly 65 and older, die of the flu each year.

Should healthy adults be worried if they can't find vaccine?
No. Healthy adults rarely get seriously ill from flu.

Can we stretch the existing supply by using smaller doses?
Not this year. Although even half-doses of some kinds of vaccine can be effective, experts will not have time to test the effectiveness of partial doses of flu vaccine for the coming season.

Can't another company make up the difference?
Again, not this season. It takes months to produce the vaccines that target flu strains, which differ every year.

Are there alternatives?
FluMist, an inhalant, is equally effective but costs more than an injected vaccine. In response to this years shortage, health-care providers have lowered the price to $22 to $30 versus $10 to $20 for a standard flu shot. In addition, the mist is approved only for healthy people aged 5 to 49.

How do you avoid catching flu?
Use common sense. Wash your hands and avoid contact with people who are sick People who feel ill should stay home and cover their mouths and noses when coughing or sneezing.

Is there any risk to the flu shot?
A sore arm. Since the shot does not contain live virus, it cannot cause the flu. Some people also worry that thimerosal, a mercury-containing preservative in some flu shots, can cause autism, but U.S. regulatory agencies and other scientists have ruled out thimerosal as a health risk.