ODP518 Three Cases of Autoimmune Thyrotoxicosis after the BNT162b2 mRNA Covid-19 Vaccine
Authors: Cheung Kitty Kit-Ting , Cheung Lorena Tsui Fun , Chow Francis Chun Chung 
Published: November 2022

Abstract

Background
Various vaccines have been produced around the world in the battle against coronavirus disease 2019 (COVID-19) in the past year. Clinical trials and approvals of these vaccines were expedited at an unprecedented speed, with some of them approved under emergency use. Since March 2021, government coordinated vaccination program using two types of vaccines against COVID-19 were being undertaken in Hong Kong. BNT162b2 mRNA COVID-19 vaccine under the name of BioNTech was one. While it is a promising measure to control COVID-19, the new mRNA vaccine technology does cast some doubts, particularly its safety. In addition to the commonly reported injection site reactions and systemic upsets, less reported reactions after this new vaccine requires more clarifications. Here, we report 3 cases of autoimmune thyrotoxicosis all happened soon after the vaccination.

Clinical Cases: Case1
A 40-year-old man with family history of thyroid cancer (mother had thyroid cancer with operation done) developed palpitations 17 days after receiving the first dose of BioNtech vaccine. Investigations confirms Graves’ thyrotoxicosis as evidenced by elevated fT4 and suppressed sTSH with positive thyroid stimulating immunoglobulin (TSI) and a diffuse vascular goiter on ultrasound (USG) thyroid. He was started on a course of anti-thyroid drug and had been advised to defer the second dose of vaccine until clinically stable.

Case2
A 44-year old lady without personal/family history of thyroid disease developed progress neck swelling and palpitation with tremor 3 days after receiving the first dose of BioNtech vaccine. Investigations confirmed Graves’ thyrotoxicosis with elevated fT4 and suppressed sTSH with positive TSI, anti-TPO, and anti-ATG. USG thyroid showed diffuse vascular goiter. She was treated with a course of anti-thyroid drug and had been advised to defer the second dose of vaccine until stabilization of thyroid function.

Case3
A 56-year-old man with positive family history of thyrotoxicosis (elder brother with history of thyrotoxicosis treated with radioactive iodine) developed progressive weight loss, increased appetite, insomnia, palpitation, and tremor around 7 days after the first dose of BioNtech vaccine. Patient only presented to an Endocrinologist for further workup 63 days after the first dose (42 days after second dose of BioNtech). Biochemically he had high fT4, suppressed sTSH, with positive anti-ATG, anti-TPO and TSI. USG thyroid revealed a small diffuse goiter. He was treated with a course of anti-thyroid drug with regular follow-up and monitoring.

Conclusion
This is the first case-series in Hong Kong demonstrating the possible triggering of Graves’ thyrotoxicosis after BioNTech vaccination. TSI and USG thyroid are invaluable tools to confirm the autoimmunity nature of the disease. Further studies are needed to clarify the prevalence, mechanisms, preventions, and treatments of this vaccine complication.
Presentation: No date and time listed