Risk of GuillainBarré syndrome after exposure to

Authors: Sara Ghaderi Nina Gunnes Inger Johanne Bakken Per Magnus Lill Trogstad Siri Eldevik Håberg

Publish Date: 2015/05/26

Volume: 31, Issue: 1, Pages: 67-72

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Abstract

Vaccinations and infections are possible triggers of GuillainBarré syndrome GBS However studies on GBS after vaccinations during the influenza AH1N1pmd09 pandemic in 2009 show inconsistent results Only few studies have addressed the role of influenza infection We used information from national health databases with information on the total Norwegian population N = 4832211 Cox regression analyses with timevarying covariates and selfcontrolled case series was applied The risk of being hospitalized with GBS during the pandemic period within 42 days after an influenza diagnosis or pandemic vaccination was estimated There were 490 GBS cases during 2009–2012 of which 410 cases occurred after October 1 2009 of which 46 new cases occurred during the peak period of the influenza pandemic An influenza diagnosis was registered for 247  of the population and the vaccination coverage was 3925  The incidence rate ratio of GBS during the pandemic peak relative to other periods was 146 95  confidence interval CI 108–198 The adjusted hazard ratio HR of GBS within 42 days after a diagnosis of pandemic influenza was 489 95  CI 117–2036 After pandemic vaccination the adjusted HR was 111 95  CI 051–243 Our results indicated that there was a significantly increased risk of GBS during the pandemic season and after pandemic influenza infection However vaccination did not increase the risk of GBS The small number of GBS cases in this study warrants caution in the interpretation of the findingsThe study was funded by the Norwegian Institute of Public Health and by the Research Council of Norway The sponsors had no role in design and conduct of the study collection management analysis and interpretation of the data and preparation review or approval of this manuscript

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