Questions about this year's flu vaccine shortage?

Here are some quick answers:

Q. Why is there a shortage?

A. Only two companies Chiron Corp. and Aventis Pasteur were making flu shots for the United States this year. British officials Tuesday suspended Chiron's license over concerns about manufacturing standards at the plant.

Q: Had any of the Chiron vaccine been distributed?

A: No, according to the company, so there is no need for a recall.

Q: What is the remaining supply of flu shots?

A: Nearly 55.4 million doses made by Aventis.

Q. Can't Aventis or some other company just make more?

A. No. Vaccine production takes several months at best, starting with growing the vaccine strain of the virus in chicken eggs and ending with vials of vaccine that must pass federal safety tests. Aventis can't make more until after November.

Q. What about diluting the vaccine to get more shots per dose?

A. Officials are discussing that, but it isn't known whether that would be safe or effective. A small National Institutes of Health study several years ago suggested that getting two doses out of each original shot could provide enough protection for healthy people.

Q: What is a flu shot, and how does it work?

A: A flu shot is an inactivated vaccine (containing killed virus) that is given with a needle, usually in the arm. It causes antibodies to develop in the body, and these antibodies provide protection against the flu.

Q. Who should get shots this year?

A. Children 6-23 months old, people 65 and older, people with underlying or chronic medical problems, pregnant women, nursing home residents, health-care workers who care for people at high risk of flu complications, child-care workers who take care of children under age 2, and children who take aspirin.

Q. What if I want the vaccine and I'm not in this group?

A. Officials are asking healthy people not to seek shots this year, so enough shots are available for those who need them most.

Q. How about that inhaled flu vaccine? Will it be available and is it safe?

A. About 1.1 million doses of MedImmune Inc.'s FluMist will be available for healthy 5-49-year-olds and health-care workers. It's made from live but weakened flu virus.

Q. Why can't the government take control and give vaccine to those who need it most?

A. Experts say the government doesn't have that authority, because vaccine has already been sold to private groups that run flu shot clinics. Trying to seize vaccine likely would set off lawsuits that could delay anyone getting the vaccine in time for the flu season.

Q. What about cities or states that bought vaccine only or mostly from Chiron?

A. Federal officials are working with Aventis to spread shipments to parts of the country most in need.

Q. How bad will the shortage be?

A. Between 90 million and 120 million Americans are at high risk of complications from the flu or have close contact with people who are.

Q: What is the risk?

A: Flu complications kill about 36,000 people in the United States each year, and put more than 200,000 in the hospital.

Q: Is this the first time that federal health officials have recommended prioritizing flu shots?

A: No. During the 2000-01 flu season, two of the nation's then-four flu shot makers had problems meeting manufacturing standards.

Sources: The Associated Press, Knight Ridder Newspapers, the Centers for Disease Control and Prevention