Sir Liam Donaldson, the Chief Medical Officer, estimated that 19,000 people would die from the virus under the "worst case scenario", a significant drop from the figure of 65,000 given in July.
He said the revised estimations, calculated by Government scientists, were "assumptions and not predictions".
They are based on one in three people across Britain becoming infected, and do not take into account what impact the swine flu vaccine, due next month, will have.
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