The letter from the Health Protection Agency, the official body that oversees public health, has been leaked to The Mail on Sunday, leading to demands to know why the information has not been given to the public before the vaccination of millions of people, including children, begins.
It tells the neurologists that they must be alert for an increase in a brain disorder called Guillain-Barre Syndrome (GBS), which could be triggered by the vaccine.
GBS attacks the lining of the nerves, causing paralysis and inability to breathe, and can be fatal.
