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

Caitlin N. Dodd*, Silvana A. Romio, Steven Black, Claudia Vellozzi, Nick Andrews, Miriam Sturkenboom, Patrick Zuber, Wei Hua, Jan Bonhoeffer, Jim Buttery, Genevieve Deceuninck, Corinne de Vries, Philippe De Wals, M. Victoria Gutierrez Gimeno, Harald Heijbel, Hayley Hughes, Kwan Hur, Anders Hviid, Jeffrey Kelman, Tehri KilpiS. K. Chuang, Kristine Macartney, Melisa Rett, Vesta Richardson Lopez-Callada, Daniel Salmon, Francisco Gimenez Sanchez, Nuria Sanz, Barbara Silverman, Jann Storsaeter, Umapathi Thirugnanam, Nicoline van der Maas, Katherine Yih, Tao Zhang, Hector Izurieta, Global H1N1 GBS Consortium

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

87 Citations (Scopus)


Background: The global spread of the 2009 novel pandemic influenza A (H1N1) virus led to the accelerated production and distribution of monovalent 2009 Influenza A (H1N1) vaccines (pH1N1). This pandemic provided the opportunity to evaluate the risk of Guillain-Barré syndrome (GBS), which has been an influenza vaccine safety concern since the swine flu pandemic of 1976, using a common protocol among high and middle-income countries. The primary objective of this project was to demonstrate the feasibility and utility of global collaboration in the assessment of vaccine safety, including countries both with and without an established infrastructure for vaccine active safety surveillance. A second objective, included a priori, was to assess the risk of GBS following pH1N1 vaccination. Methods: The primary analysis used the self-controlled case series (SCCS) design to estimate the relative incidence (RI) of GBS in the 42 days following vaccination with pH1N1 vaccine in a pooled analysis across databases and in analysis using a meta-analytic approach. Results: We found a relative incidence of GBS of 2.42 (95% CI 1.58-3.72) in the 42 days following exposure to pH1N1 vaccine in analysis of pooled data and 2.09 (95% CI 1.28-3.42) using the meta-analytic approach. Conclusions: This study demonstrates that international collaboration to evaluate serious outcomes using a common protocol is feasible. The significance and consistency of our findings support a conclusion of an association between 2009 H1N1 vaccination and GBS. Given the rarity of the event the relative incidence found does not provide evidence in contradiction to international recommendations for the continued use of influenza vaccines.

Original languageEnglish
Pages (from-to)4448-4458
Number of pages11
Issue number40
Publication statusPublished - 13 Sept 2013
Externally publishedYes


  • Adjuvant
  • Adverse events following immunization (AEFI)
  • Guillain Barré Syndrome (GBS)
  • International
  • Monovalent H1N1 Vaccine (H1N1)
  • Self-controlled case-series method (SCCS)


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