Chiron, which said it would co-operate fully with the investigation, was instructed to surrender to the US attorney's office for the Southern District of New York, documents and materials that would explain the events leading up to the suspension by the UK's Medicines and Healthcare products Regulatory Agency (MHRA).
Since the ban there has been speculation about the way the problems with Chiron's Liverpool plant emerged. The US justice department is said to be particularly interested in whether or not there was a delay in informing authorities about any flaws in Chiron's manufacturing process.
Chiron's failure to monitor manufacturing practices lead to the vaccine becoming contaminated with a bacteria called Serratia. As a result Chiron could not export the 48 million flu vaccine doses, which accounted for nearly half the expected demand in the US.
As Chiron's production problems illustrate, vaccine-making has the potential to produce more errors than drug manufacture, due to the nature of its production methods. Although Chiron's contribution will be missed the shortfall could almost certainly be met by Aventis Pasteur, part of theSanofi-Aventis Group, which will ship in 22.4 million doses of flu vaccine to the US.
The French drug group has been called in by the US Centre for DiseaseControl and Prevention for the 2004-2005 winter.
High production costs combined with low revenues have driven many drug companies out of the vaccine business, leading to frequent shortages of a variety of vaccines. Doctors ran out of flu shots last year. Since 2001, there have been shortages of vaccines against eight diseases, including tetanus, measles and rubella.
Vaccines are often more costly to produce than drugs because they are made from live viruses, instead of chemicals. Making a vaccine can require hundreds of steps, each subject to stringent sterility guidelines. Yet manufacturers are often unable to sell the vaccines at a price high enough to make a profit.