Abstract
Aims/hypothesisDuring the A/H1N1 2009 (A/California/04/2009) pandemic, mass vaccination with a squalene-containing vaccine, Pandemrix®, was performed in Sweden and Finland. The vaccination was found to cause narcolepsy in children and young adults with the HLA-DQ 6.2 haplotype. The aim of this study was to investigate if exposure to Pandemrix® similarly increased the risk of islet autoimmunity or type 1 diabetes.MethodsIn The Environmental Determinants of Diabetes in the Young (TEDDY) study, children are followed prospectively for the development of islet autoimmunity and type 1 diabetes. In October 2009, when the mass vaccination began, 3401 children at risk for islet autoimmunity and type 1 diabetes were followed in Sweden and Finland. Vaccinations were recorded and autoantibodies against insulin, GAD65 and insulinoma-associated protein 2 were ascertained quarterly before the age of 4 years and semi-annually thereafter.ResultsBy 5 August 2010, 2413 of the 3401 (71%) children observed as at risk for an islet autoantibody or type 1 diabetes on 1 October 2009 had been vaccinated with Pandemrix®. By 31 July 2016, 232 children had at least one islet autoantibody before 10 years of age, 148 had multiple islet autoantibodies and 96 had developed type 1 diabetes. The risk of islet autoimmunity was not increased among vaccinated children. The HR (95% CI) for the appearance of at least one islet autoantibody was 0.75 (0.55, 1.03), at least two autoantibodies was 0.85 (0.57, 1.26) and type 1 diabetes was 0.67 (0.42, 1.07). In Finland, but not in Sweden, vaccinated children had a lower risk of islet autoimmunity (0.47 [0.29, 0.75]), multiple autoantibodies (0.50 [0.28, 0.90]) and type 1 diabetes (0.38 [0.20, 0.72]) compared with those who did not receive Pandemrix®. The analyses were adjusted for confounding factors.Conclusions/interpretationChildren with an increased genetic risk for type 1 diabetes who received the Pandemrix® vaccine during the A/H1N1 2009 pandemic had no increased risk of islet autoimmunity, multiple islet autoantibodies or type 1 diabetes. In Finland, the vaccine was associated with a reduced risk of islet autoimmunity and type 1 diabetes.
Highlights
Clinical diagnosis of type 1 diabetes is preceded by an autoimmune destructive process against the pancreatic islet beta cells; a prodromal period that may last a few months or several years
Of the 3401 children considered at risk for type 1 diabetes as of 1 October 2009, 2413 (70.9%) were vaccinated with Pandemrix®
We investigated whether risk of islet autoimmunity and type 1 diabetes is increased in children who have been vaccinated with the squalene (ASO3)containing H1N1 flu vaccine (Pandemrix®)
Summary
Clinical diagnosis of type 1 diabetes is preceded by an autoimmune destructive process against the pancreatic islet beta cells; a prodromal period that may last a few months or several years. The risk of developing autoimmunity in genetically susceptible children is widely considered to be increased by perinatal or early childhood environmental exposures [1]. In The Environmental Determinants of Diabetes in the Young (TEDDY) study, we have the opportunity to analyse triggers in relation to seroconversion to islet autoimmunity as a first primary endpoint, as over 70% of children with multiple islet autoantibodies develop type 1 diabetes over a 10-year period [4]. It has been speculated that vaccinations early in life may alter the immune response to infections, leading to a disturbed capacity to distinguish between self and non-self and thereby increasing the risk of autoimmune reactions. Previous studies do not support the notion that type 1 diabetes can be triggered by vaccinations [5, 6]
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