Nearly half the USA's expected supply of flu vaccine won't be delivered because British health authorities suspended Chiron Corp.'s (CHIR) license to make it.

The announcement came roughly a month before flu season starts, and raises concern about whether there will be enough vaccine to protect children, older Americans and others who are at greatest risk.

Healthy people are being encouraged to not get the vaccine to ensure that there is enough left for the people who need it the most. Doctors are being told to give vaccine first to babies ages 6 months to 23 months; people 65 and older; anyone with chronic health problems, such as heart or lung disease; and pregnant women. Health care workers and people in close contact with anyone in the high-risk groups also should be vaccinated.

Gerberding said Aventis Pasteur, the only other major maker of flu shots, expects to meet its production goal of 54 million doses, and health officials are working to assure that it is evenly distributed.

In an average year, flu kills 36,000 people in the USA and causes more than 200,000 hospitalizations. The season typically runs from November through March.

Officials have said that this is not really a reason to worry.