Objective To record clinical findings in all new cases of Guillain–Barré syndrome (GBS) or Fisher syndrome (FS) in UK children in the 2 years following September 2009 and determine the proportion temporally associated with recent infections, pandemic H1N1 (2009) strain influenza vaccination or seasonal influenza vaccination.

Design A prospective UK-wide epidemiological study using the British Paediatric Surveillance Unit system.

Patients Children aged 16 years or less meeting the Brighton Collaboration criteria for GBS or FS.

Results 112 children with GBS (66 boys and 46 girls) and 3 boys with FS were identified in 2 years. All but one recovered sufficiently to go home. The annual UK incidence rate of GBS in patients less than 15 years old was 0.45/100 000, similar to other countries. There was evidence of infection in the 3 months preceding onset in 92/112 GBS and 3/3 FS cases. Of those living in England, 7 cases received pandemic A/H1N1 2009 influenza vaccination before GBS symptom onset (3/7 were within 6 months including 1 within 3 months); 2 children received 2010/2011 seasonal influenza vaccination within 6 months of GBS onset. The numbers vaccinated were not significantly greater than expected by chance.

Conclusions The outcome for childhood GBS and FS after 6 months was better than reported in adults. Most UK GBS and FS cases had infections in the preceding 3 months. When considering the children living in England, there was no significantly increased risk of GBS after pandemic A/H1N1 2009 influenza vaccination or 2010/2011 seasonal influenza vaccination.