Doctors have been put on alert for cases of a nerve disease following the introduction of a vaccine for swine flu, it has emerged.
Health chiefs said there was an increased risk of developing Guillain-Barre syndrome after a flu-like illness, but stressed there was no evidence linking it to the vaccination.
The syndrome, which affects about 1,500 people a year in the UK, attacks the nervous system and can result in temporary paralysis.
Its exact cause is unclear but many people affected by it have had a viral or bacterial infection a few weeks earlier.
A Health Protection Agency (HPA) spokesman said enhanced surveillance was "routine" when introducing a new vaccine.
More than 13 million people in the UK, including people with asthma, diabetes, heart disease, renal disease or with a compromised immune system, will get the jab from October. It is anticipated the normal seasonal flu vaccine may be given at the same time.
The spokesman said: "Guillain-Barre syndrome has long been identified as a potential adverse event that would require enhanced surveillance following the introduction of a pandemic vaccine, but there is no evidence to suggest there is an increased risk of Guillain-Barre syndrome from this vaccine.
"There is robust evidence that no increased risk of Guillain-Barre syndrome arises from seasonal flu vaccination.
"Establishing enhanced surveillance on Guillain-Barre syndrome has always been part of our pandemic plan because there is an increased risk of this disease after a flu-like illness.
"The HPA is working in collaboration with the Association of British Neurologists Surveillance Unit (BNSU) and the British Paediatric Surveillance Unit (BPSU) who will ask clinicians to report each month whether they have seen any cases of Guillain-Barre syndrome."
