INTRODUCTION: It has been suggested that the H1N1 vaccine may be a trigger for 
the onset of narcolepsy-cataplexy, a rare disease whose autoimmune origin is 
suspected.
OBSERVATIONS: We report two patients (a 9-year-old boy and an 18-year-old man) 
with severe narcolepsy-cataplexy, in whom the illness appeared within 3-4 weeks 
after H1N1 vaccination. In both cases, symptoms developed unusually abruptly and 
they presented with severe daytime sleepiness and multiple daily cataplexy 
attacks. Other similar cases have been recently reported associated with 
H1N1 vaccine.
CONCLUSION: Although no formal link can be established, the unusual 
characteristics of the reported cases and the striking temporal relationship 
suggests that narcolepsy may be the result of an autoimmune reaction triggered 
by H1N1 vaccination in susceptible individuals.