The leaked letter refers to the use of a similar swine flu vaccine in the United States in 1976 when:
More people died from the vaccination than from swine flu.
500 cases of a brain disorder called Guillain-Barre Syndrome (GBS) were detected.
The H1N1 vaccine may have increased the risk of contracting GBS by eight times.
The 1975 vaccine was withdrawn after just ten weeks when the link with GBS became clear.
The US Government was forced to pay out millions of dollars to those affected. Read more: