This may reflect a healthy selection of people for those vaccinated and that our risk estimates for neurological and autoimmune outcomes may be underestimates. Comparisons Pancreatic cancer with previous studies and findings Most available data on the safety of A (H1N1) pandemic vaccines��with Pandemrix being the most commonly used vaccine in the European Union (estimated use in some 30 million)��are based on reports of spontaneous adverse drug events to national regulatory agencies. Such data have been generally reassuring during and after the pandemic period. However, an increased risk of narcolepsy in children and adolescents, with increased relative risks ranging from fourfold to ninefold, have been recently reported from authorities in Sweden and Finland,17 18 19 leading to regulatory action by the European drug regulatory body, the European Medicines Agency, in July 2011 to restrict the use of Pandemrix vaccinations.

25 Regarding other outcomes, some pertinent conclusions can be drawn from published studies on the safety of influenza vaccinations in general. Although previous studies have produced conflicting results on an association between Guillain-Barr�� syndrome and influenza vaccination,8 9 10 26 two larger studies reported no positive association.27 28 In our study we found no association between vaccination with an adjuvanted H1N1 vaccine and Guillain-Barr�� syndrome. Our findings are consistent with a Chinese study of a non-adjuvanted pandemic vaccine14 and add to that study because we were able to estimate hazard ratios and our study population was not restricted to previously healthy people.

Although a large number of studies have examined the association between various types of vaccinations and type 1 diabetes,29 30 31 32 none has shown an association.33 To our knowledge no studies have been carried out on influenza vaccinations (for example, using squalene adjuvanted vaccines) and risk of type 1 diabetes. In our study we found no association between H1N1 vaccination and type 1 diabetes in AV-951 the age group where most cases of the disease occur (those born in 1990 and later). The excess risk for paraesthesia may constitute a local symptom (for example, pain, redness, swelling, tingling) at the injection site from the H1N1 vaccination. The excess risk of paraesthesia was only of borderline significance (95% confidence interval 1.00 to 1.23) and absent in patients undergoing vaccination in the late phase. We cannot explain the small increase in risk for Bell��s palsy seen in this study. Potential causes include viral infection and pregnancy, neither of which could be dealt with using the data in our analyses. The absolute risk of Bell��s palsy was low, 6.4 cases per 100000 vaccinated population.