The nation's supply of flu vaccine could face a shortage after a company in San Francisco announced it found tainted doses in its factory.
Chiron Corporation said Thursday it will hold up shipment of about 50 million shots while it investigates what went wrong and determines whether the vaccine is safe to use. That's about half the supply U.S health officials had hoped to have on hand this year.
U.S. health officials say some people may not get flu shots when they want this year, but that they are hopeful Chiron's production problems are only temporary. Demand typically peaks in October and November.
The head of the federal Centers for Disease Control and Prevention in Atlanta, Dr. Julie Gerberding, says health officials do not expect a major delay.
The CDC says flu kills 36,000 people in an average year and hospitalizes another 114,000, primarily the elderly.
Last year's flu season got off to an unusually early and harsh start, which raised fears and caused demand for vaccines to outstrip supply for the first time.