I5 Swine ‘flu vaccination – the good news and the bad news

Abstract

Background Guillain-Barre syndrome (GBS) can be associated with ‘swine ‘flu’ vaccination, so in 2009 surveillance for GBS and Fisher syndrome (FS) was established via the British Paediatric Surveillance Unit (BPSU) before UK immunisation against pandemic H1N1 influenza commenced. Then in 2010 there were reports from Scandinavia of an association between narcolepsy and Pandemrix (a monovalent pandemic strain ‘flu vaccine containing the oil-in-water adjuvant AS03). To investigate this in the UK it was necessary to identify retrospectively children who had been diagnosed with narcolepsy from before the 2009 pandemic: the BPSU system was not suitable for this. Results BPSU GBS study : 112 children with GBS (66 boys and 46 girls) and 3 boys with FS were identified between September 2009 and September 2011 inclusive. There was an infection in the 3 months preceding onset in 92/112 GBS and 3/3 FS cases. In England, 7 had received pandemic A/H1N1 seasonal influenza vaccine before GBS onset (3/7 within 6 months, including 1 within 3 months). The number of GBS cases who had been vaccinated was no greater than expected by chance. Narcolepsy study : 16 sleep centres and paediatric neurology centres in England identified 75 cases aged 4–18 years with narcolepsy onset after January 1 st 2008. Eleven were vaccinated before onset; seven within 6 months. The odds ratio for vaccination at any time prior to onset in cases diagnosed by July 2011 was 14·4 (95% confidence intervals 4·3 to 48·5) and 16·2 (3·1 to 84·5) for vaccination within 6 months of onset. The relative incidence in a self-controlled case series analysis with onset from October 2008 to December 2010 was 9·9 (2·1 to 47·9). The attributable risk was between 1 in 57 500 and 1 in 52 000 doses. Conclusion The BPSU GBS study found no increased risk of GBS in those children living in England after pandemic A/H1N1 2009 influenza vaccine or 2010/2011 seasonal influenza vaccine. In contrast, the narcolepsy study indicated that there was a causal association between vaccination with AS03 adjuvanted pandemic A/H1N1 vaccine and narcolepsy, confirming reports from Finland and Sweden.