Clinical features of narcolepsy in children vaccinated with AS03 adjuvanted pandemic A/H1N1 2009 influenza vaccine in England

Dev Med Child Neurol. 2014 Nov;56(11):1117-23. doi: 10.1111/dmcn.12522. Epub 2014 Jul 10.


Aim: The aim of this study was to investigate whether children in England with narcolepsy who received the ASO3 adjuvanted pandemic A/H1N1 2009 influenza vaccine (Pandemrix) differed clinically from unvaccinated patients.

Method: A retrospective review was conducted in children with narcolepsy diagnosed by sleep centres and paediatric neurologists in 16 English hospitals. The inclusion criteria were patient age 4 to 18 years, onset of narcolepsy after January 2008, and diagnosis by the time of the key data-gathering visit in 2011. Clinical data came from hospital notes and general practitioner questionnaires. An expert panel validated the diagnoses.

Results: Seventy-five patients with narcolepsy were identified (43 males, 32 females; mean age at onset 10y 4mo, range 3-18y). Of these patients, 11 received the Pandemrix vaccine before narcolepsy onset. On first presentation, there were more frequent reports of cataplexy, among other features, in vaccinated than in unvaccinated patients (82% vs 55%), but only excessive weight gain (55% vs 20%) was significantly more frequent (p=0.03). Facial hypotonia (p=0.03) and tongue protrusion (p=0.01) were eventually seen more frequently in vaccinated children. When considering patients diagnosed within a year of onset, vaccinated children were not diagnosed more rapidly than unvaccinated children.

Interpretation: Some symptoms and signs of narcolepsy were more frequently reported in Pandemrix-vaccinated patients. There was no evidence of the more rapid diagnosis in vaccinated patients that has been reported in Finland and Sweden.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Child
  • Child, Preschool
  • England / epidemiology
  • Facial Muscles
  • Female
  • Humans
  • Influenza Vaccines / administration & dosage*
  • Influenza Vaccines / adverse effects*
  • Male
  • Medical Records
  • Muscle Hypotonia / etiology
  • Narcolepsy / epidemiology*
  • Narcolepsy / virology*
  • Retrospective Studies
  • Surveys and Questionnaires
  • Tongue / physiopathology
  • Vaccination / adverse effects*


  • Influenza Vaccines
  • pandemrix