title: Chart-confirmed guillain-barre syndrome after 2009 H1N1 influenza vaccination among the Medicare population, 2009-2010.
abstract: Given the increased risk of Guillain-Barré Syndrome (GBS) found with the 1976 swine influenza vaccine, both active surveillance and end-of-season analyses on chart-confirmed cases were performed across multiple US vaccine safety monitoring systems, including the Medicare system, to evaluate the association of GBS after 2009 monovalent H1N1 influenza vaccination. Medically reviewed cases consisted of H1N1-vaccinated Medicare beneficiaries who were hospitalized for GBS. These cases were then classified by using Brighton Collaboration diagnostic criteria. Thirty-one persons had Brighton level 1, 2, or 3 GBS or Fisher Syndrome, with symptom onset 1-119 days after vaccination. Self-controlled risk interval analyses estimated GBS risk within the 6-week period immediately following H1N1 vaccination compared with a later control period, with additional adjustment for seasonality. Our results showed an elevated risk of GBS with 2009 monovalent H1N1 vaccination (incidence rate ratio = 2.41, 95% confidence interval: 1.14, 5.11; attributable risk = 2.84 per million doses administered, 95% confidence interval: 0.21, 5.48). This observed risk was slightly higher than that seen with previous seasonal influenza vaccines; however, additional results that used a stricter case definition (Brighton level 1 or 2) were not statistically significant, and our ability to account for preceding respiratory/gastrointestinal illness was limited. Furthermore, the observed risk was substantially lower than that seen with the 1976 swine influenza vaccine.
authors: Laura L
authors: LL
authors: Polakowski
authors: Sukhminder K
authors: SK
authors: Sandhu
authors: David B
authors: DB
authors: Martin
authors: Robert
authors: R
authors: Ball
authors: Thomas E
authors: TE
authors: Macurdy
authors: Riley L
authors: RL
authors: Franks
authors: Jonathan M
authors: JM
authors: Gibbs
authors: Garner F
authors: GF
authors: Kropp
authors: Armen
authors: A
authors: Avagyan
authors: Jeffrey A
authors: JA
authors: Kelman
authors: Christopher M
authors: CM
authors: Worrall
authors: Guoying
authors: G
authors: Sun
authors: Rebecca E
authors: RE
authors: Kliman
authors: Dale R
authors: DR
authors: Burwen
mesh_terms: D000368:Aged; D005260:Female; D005767:Gastrointestinal Diseases / Q000150:complications*; D020275:Guillain-Barre Syndrome / Q000139:chemically induced* / Q000145:classification / Q000453:epidemiology / Q000209:etiology; D006760:Hospitalization; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000009:adverse effects*; D007251:Influenza, Human / Q000276:immunology / Q000517:prevention & control*; D007345:Insurance Claim Review; D008297:Male; D006278:Medicare / Q000706:statistics & numerical data*; D019846:Miller Fisher Syndrome / Q000139:chemically induced / Q000145:classification / Q000453:epidemiology / Q000209:etiology; D016012:Poisson Distribution; D012140:Respiratory Tract Diseases / Q000150:complications*; D014481:United States / Q000453:epidemiology
chemical_list: D007252:Influenza Vaccines
keywords: Fisher Syndrome; Guillain-Barré Syndrome; human influenza; vaccination