title: The Guillain-Barré syndrome and the 1992-1993 and 1993-1994 influenza vaccines.
abstract: BACKGROUND
  The number of reports of influenza-vaccine-associated Guillain-Barré syndrome to the national Vaccine Adverse Event Reporting System increased from 37 in 1992-1993 to 74 in 1993-1994, arousing concern about a possible increase in vaccine-associated risk.
  
  
  METHODS
  Patients given a diagnosis of the Guillain-Barré syndrome in the 1992-1993 and 1993-1994 influenza-vaccination seasons were identified in the hospital-discharge data bases of four states. Vaccination histories were obtained by telephone interviews during 1995-1996 and were confirmed by the vaccine providers. Disease with an onset within six weeks after vaccination was defined as vaccine-associated. Vaccine coverage in the population was measured through a random-digit-dialing telephone survey.
  
  
  RESULTS
  We interviewed 180 of 273 adults with the Guillain-Barré syndrome; 15 declined to participate, and the remaining 78 could not be contacted. The vaccine providers confirmed influenza vaccination in the six weeks before the onset of Guillain-Barré syndrome for 19 patients. The relative risk of the Guillain-Barré syndrome associated with vaccination, adjusted for age, sex, and vaccine season, was 1.7 (95 percent confidence interval, 1.0 to 2.8; P=0.04). The adjusted relative risks were 2.0 for the 1992-1993 season (95 percent confidence interval, 1.0 to 4.3) and 1.5 for the 1993-1994 season (95 percent confidence interval, 0.8 to 2.9). In 9 of the 19 vaccine-associated cases, the onset was in the second week after vaccination, all between day 9 and day 12.
  
  
  CONCLUSIONS
  There was no increase in the risk of vaccine-associated Guillain-Barré syndrome from 1992-1993 to 1993-1994. For the two seasons combined, the adjusted relative risk of 1.7 suggests slightly more than one additional case of Guillain-Barré syndrome per million persons vaccinated against influenza.
authors.affiliation: Department of Epidemiology and Preventive Medicine, School of Medicine, University of Maryland, Baltimore 21201, USA.
authors.forename: T
authors.initials: T
authors.lastname: Lasky
authors.forename: G J
authors.initials: GJ
authors.lastname: Terracciano
authors.forename: L
authors.initials: L
authors.lastname: Magder
authors.forename: C L
authors.initials: CL
authors.lastname: Koski
authors.forename: M
authors.initials: M
authors.lastname: Ballesteros
authors.forename: D
authors.initials: D
authors.lastname: Nash
authors.forename: S
authors.initials: S
authors.lastname: Clark
authors.forename: P
authors.initials: P
authors.lastname: Haber
authors.forename: P D
authors.initials: PD
authors.lastname: Stolley
authors.forename: L B
authors.initials: LB
authors.lastname: Schonberger
authors.forename: R T
authors.initials: RT
authors.lastname: Chen
mesh_terms: D000293:Adolescent; D000328:Adult; D016907:Adverse Drug Reaction Reporting Systems; D000368:Aged; D000369:Aged, 80 and over; D003625:Data Collection; D005260:Female; D006801:Humans; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D011129:Polyradiculoneuropathy / Q000453:epidemiology / Q000209:etiology*; D012306:Risk; D014481:United States / Q000453:epidemiology
chemical_list: D007252:Influenza Vaccines