Introduction:Following the H1N1 influenza epidemic of 2009/2010, we noted an increase in the number of children presenting with narcolepsy.  This has been examined nationally with a link to H1N1 vaccine identified¹.  We compared patients who had received H1N1 vaccination to those patients who had no significant vaccine exposure.

Methods:We prospectively collected data on referrals with narcolepsy received between December 2009 and December 2012, in addition to retrospective review of all cases from January 2006 to December 2009. We examined data for symptom complex experienced, investigation results, vaccine exposure, and if positive, time lag from vaccination to symptom onset.

Results:48 patients were diagnosed with narcolepsy, 43 had a history of H1N1 vaccination prior to symptom onset.Average age of symptom onset was 10.2 years, with a lag from vaccine to symptom onset of 0.3 years in those who had received vaccination.Average age of symptom onset in unvaccinated patients was 8.25 years. Incidence of cataplexy was 3 in 4 for vaccinated patients, versus 4 in 5 unvaccinated patients.Where results are available to date, 32/33 had positive HLA typing for DQB1:0602 in vaccine related patients, and 4/5 unvaccinated patients were positive.

Conclusion:There is an increased incidence of narcolepsy related to H1N1 vaccination, likely to have an immune aetiology.Vaccinated and unvaccinated groups present as homogenous in terms of symptoms experienced and investigation results.