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Can Vaccinations Increase Or Decrease Risk for Type 1 Diabetes?

Flu shot, Pandemrix®, might reduce diabetes risk in children, study found.

Type 1 diabetes results from autoimmune destruction of pancreatic islet β-cells. Although the cause is unknown, genetic and environmental factors are believed to be involved.

Polymorphisms of class II HLA genes encoding DQ and DR, by far, is the strongest predictor of type 1 diabetes risk. Vaccinations are among the environmental factors that have been studied. It has been suspected that childhood vaccinations may alter the immune system, thereby increasing the risk of autoimmune reactions. However, previous studies have not found any evidence to support the association between vaccination and an increased risk of type 1 diabetes.

During the influenza A H1N1 pandemic in 2009, mass vaccination with Pandemrix®, a vaccine containing the squalene-based adjuvant ASO3, was done for children and adults in Sweden and Finland. A few months after the vaccination, the incidence of new narcolepsy diagnoses increased in both countries, especially in children and young adults. The mechanism of this effects is not fully understood, but it seems that Pandemrix® could contribute to the induction of orexin-specific autoimmunity. As such, researchers hypothesized that this vaccine may not only induce autoimmunity to orexin-producing cells but also to islet autoantigens. A recent observational study, the Environmental Determinants of Diabetes in the Young (TEDDY), was done to investigate whether the risk of islet autoimmunity and type 1 diabetes is increased in children who have been vaccinated with Pandemrix®.

A population of 8,676 children was recruited for this study (4,318 children from the United State or Germany, 4,358 children from Sweden or Finland); however, only 3,401 children were still considered at risk for developing type 1 diabetes by October 1, 2009. All children were followed up for outcomes starting from October 1, 2009. Of the 3,401 children, 2,413 children (70.9%) were vaccinated with Pandemrix®. During the first 4 years, all children were examined every three month. Thereafter, children who still at risk for islet autoimmunity were being followed biannually until the age of 15 years old. Children who developed one or several islet autoantibodies were still being monitored every 3 months after 4 years of age.

As of July 2016, 232 children had developed islet autoantibodies (135 in Sweden and 97 in Finland), 148 children had developed multiple islet autoantibodies (81 in Sweden and 67 in Finland) and 96 had developed type 1 diabetes (47 in Sweden and 49 in Finland). Most of outcome data were collected from the Swedish and Finnish children groups because of the heterogeneity and low numbers in the German population and different types of vaccines that were used for the H1N1 vaccination program in the US population. Data from the study did not support the proposed hypothesis and any connection between Pandemrix® and the risk of type 1 diabetes. The risk of any islet autoantibody, multiple islet autoantibodies or type 1 diabetes was not increased among the vaccinated children; (HR 0.76 [95% CI 0.57, 1.02]), (HR 0.92 [95% CI 0.63, 1.35]), and (HR 0.68 [95% CI 0.43, 1.06]), respectively. Data also suggested that the risk of type 1 diabetes in Finland was actually lower in children who vaccinated against H1N1 than in children who were not vaccinated. It is unclear as to why there was no increased risk among the vaccinated population even though the incidence of type 1 diabetes was higher in Finnish children than in Swedish children. After adjusting for seasonal flu vaccination, during and after pregnancy, the associations remained unchanged between the risk of type 1 diabetes and the vaccinated children. This finding could indicate that Pandemrix® might reduce the risk of type 1 diabetes in higher risk populations.

Practice Pearls:

  • This study did not find any increased risk of islet autoimmunity, multiple islet autoantibodies or type 1 diabetes in children who were given the Pandemrix® flu vaccination
  • Pandemrix® might reduce the risk of type 1 diabetes by unknown mechanism.
  • Additional studies are needed to further explore the effects of influenza vaccinations.

References:

Helena L, Kristian L. Maria L. Michael H. Ake L. William H. Jin-Xiong S. Olli S. Jorma T. Anette-G. Z. Beena A. Jeffrey K. Marian R. Heikki H. Pandemrix® vaccination is not associated with increased risk of islet autoimmunity or type 1 diabetes in the TEDDY study children. Diabetologia. 2017 October 9.

Kay Lynn Tran, Doctor of Pharmacy Candidate: Class of 2018; LECOM College of Pharmacy