Guillain-Barre syndrome and H1N1 (2009) pandemic influenza vaccination using an AS03 adjuvanted vaccine in the United Kingdom: Self-controlled case series

In 1976 a swine influenza vaccine was associated with an increased risk of Guillain-Barre syndrome (GBS). Although subsequent studies did not find an increased risk of CBS following seasonal influenza vaccine, there was concern that the monovalent H1N1 vaccines developed against the swine influenza pandemic of 2009 might increase the risk of GBS. In the UK a split-virion AS03 oil-in-water adjuvanted vaccine (Pandemrix (TM)) was predominantly used. To determine whether the risk of CBS increased after Pandemrix administration, we sought CBS cases during the period of vaccine use from neurologists and a patient support group, and following the vaccination period from hospital episode statistics (HES) in England. We obtained cases' vaccination histories and illness onset dates from general practitioners. We determined the relative incidence of CBS in the 6 weeks after vaccination using the self-controlled case series method on the cases identified in HES. We included 327 CBS cases, of whom 37 received pandemic vaccine in the study period, nine of whom developed GBS within 6 weeks of vaccination (relative incidence 1.05 [95% confidence interval (CI) 0.37 to 2.24]). We found no evidence of an increased risk of CBS in the 6 weeks following pandemic influenza vaccination. (C) 2011 Elsevier Ltd. All rights reserved.