title: No association between influenza A(H1N1)pdm09 vaccination and narcolepsy in South Korea: an ecological study.
abstract: BACKGROUND
  There is concern about a possible association between influenza A(H1N1)pdm09 vaccination and narcolepsy. In this study, we assessed the incidence and incidence rate of narcolepsy in the South Korean population before and after the implementation of an A(H1N1)pdm09 vaccination campaign to see if vaccination led to a change in the occurrence of narcolepsy.
  
  
  METHODS
  We conducted an ecological study, comparing incident cases and incidence rates for newly diagnosed narcolepsy case-patients in South Korea, between July 2006 and June 2011. We used data from the Health Insurance Review Agency and Korea Centers for Disease Control and Prevention, which have limited information on case ascertainment. During vaccination campaign period, South Korea used non-adjuvanted and MF59-adjuvanted A(H1N1)pdm09 vaccines.
  
  
  RESULTS
  Generally, incidence rate was highest in prepandemic period. No trend toward increase in the incidence of narcolepsy after pandemic period was found. Observation of incidence by season did not suggest any time pattern for occurrence of narcolepsy.
  
  
  CONCLUSIONS
  No increase in cases or incidence rate for narcolepsy during the A(H1N1)pdm09 vaccination campaign was found in South Korea. Our data do not support the use of MF59-adjuvanted or non-adjuvanted A(H1N1)pdm09 vaccine as a trigger for narcolepsy on a population level.
authors.affiliation: Division of Vaccine Preventable Disease Control and National Immunization Program, Republic of Korea. choeyj@yahoo.com
authors.forename: Young June
authors.initials: YJ
authors.lastname: Choe
authors.forename: Geun-Ryang
authors.initials: GR
authors.lastname: Bae
authors.forename: Duk-hyoung
authors.initials: DH
authors.lastname: Lee
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D015994:Incidence; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000009:adverse effects* / Q000276:immunology; D007251:Influenza, Human / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D009290:Narcolepsy / Q000139:chemically induced* / Q000453:epidemiology*; D056910:Republic of Korea / Q000453:epidemiology; D014611:Vaccination / Q000009:adverse effects; D055815:Young Adult
chemical_list: D007252:Influenza Vaccines