Neurologic adverse events following influenza A (H1N1) vaccinations in children.

Background: Since the monovalent pandemic influenza A (H1N1) vaccine was recommended worldwide in October 2009, there has been a shortage of pediatric clinical data for post-vaccine neurologic adverse events (NAE), including Guillain-Barré syndrome. We reviewed pediatric NAE data following H1N1 vaccinations and for patients with peripheral neuropathy, we followed their progress.

Methods: In our single-center study, we retrospectively reviewed 14 cases of children who visited the Division of Pediatric Neurology in the Department of Pediatrics of Chonnam National University Hospital due to NAE following monovalent influenza A (H1N1) vaccination between November 2009 and March 2010.

Results: Clinical diagnoses for major NAE included: polyneuropathy in the extremities (11/14, 78.6%), sensory mononeuropathy with numbness in the left fibula area (1/14, 7.1%), Bell's palsy (1/14, 7.1%) and recent-onset acute headache only (1/14, 7.1%). Therefore, most patients were diagnosed as having peripheral neuropathy (13/14, 92.9%), and two met the Brighton Collaboration Guillain-Barré syndrome definition criteria for level 3 (the lowest level of diagnostic certainty).

Conclusions: Post-vaccine NAE were mainly motor weakness due to polyneuropathy, which had a good prognosis of complete improvement within a few months without sequelae.