Risk of Guillain-Barré Syndrome Following H1N1 Influenza Vaccination in Quebec

Abstract

UILLAIN-BARRÉ SYNDROME (GBS) is a peripheral neuropathy with acute onset and is characterized, in its typical presentation, by rapidly developing motor weakness and areflexia. 1,2 The disease is thought to be autoimmune and triggered by a stimulus of external origin. 1,2 In 1976-1977, an unusually high rate of GBS was identified in the United States following the administration of inactivated "swine" influenza A(H1N1) vaccines. 3 In 2003, the Institute of Medicine (IOM) concluded that the evidence favored acceptance of a causal relationship between the 1976 swine influenza vaccines and GBS in adults. 4 Studies of seasonal influenza vaccines administered in subsequent years have found small or no increased risk. 5 In mice, different influenza vaccines can induce antiganglioside antibodies that are associated with the development of GBS in humans. 6 Extrapolation of results of animal studies to humans, however, is

International collaboration to assess the risk of Guillain Barré Syndrome following Influenza A (H1N1) 2009 monovalent vaccines

“…This risk is consistent with the level of risk reported by others. Estimates from single-country studies ranged from 1.05 to 4.70, the majority of which reported statistically significant increased risk [23][24][25][26][27][28][29][30][31][32]. Estimates were lower in studies of adjuvanted vaccines (1.05-3.04) [25,31] than in non-adjuvanted vaccines (1.57-4.70) [26][27][28][29][30]32].…”

Risk of Guillain-Barré syndrome after exposure to pandemic influenza A(H1N1)pdm09 vaccination or infection: a Norwegian population-based cohort study

“…A Canadian study showed a small but significant increase in the number of GBS cases after mass influenza vaccination in Quebec [21] and a study from Germany on the Pandemrix vaccine reported a statistically significant association between GBS and vaccination in a 5-42 days risk window [6]. Unlike other studies, an American study by Vellozzi et al [22] suggested a protective effect of influenza A (H1N1) vaccination.…”

“…Previous studies on GBS following the 2009 pandemic were mainly based on case-centre designs (collaborations between various health centres) [3], records collected from selected hospitals [6,20,21], or a case-control design [14]. These studies are therefore prone to biases from selection of participants, the methods of collecting information and recall bias.…”

“…These studies are therefore prone to biases from selection of participants, the methods of collecting information and recall bias. Many studies have been limited to a few counties or states [21,22]. Risk of Guillain-Barré syndrome after exposure to pandemic influenza A(H1N1)pdm09 vaccination… 69…”

“…While some studies show a lack of association between GBS following influenza A (H1N1) vaccination [3,8,9,14,20], an increased risk of GBS following pandemic vaccination has been reported in other studies [5,6,21,22]. Many of these studies, however, did not address influenza infection as a risk factor for GBS.…”