ABSTRACT
Thyroiditis is an inflammatory process that can be triggered by infection, autoimmune diseases, medications, post-partum, and in very rare instances, vaccine adjuvants. In this case report, we focus on the latter cause of thyroiditis as we discuss a 35-year-old male who developed palpitations, heat intolerance, and night sweats after receiving the first dose of the COVID-19 Pfizer-BioNTech vaccine. Our patient presented with clinical symptoms of hyperthyroidism ten days after receiving the vaccine and he did not have a painful thyroid. Initial laboratory studies showed a suppressed TSH, elevated free triiodothyronine (FT3) and free thyroxine (FT4), elevated erythrocyte sedimentation rate (ESR) and c-reactive protein (CRP) and negative thyroid autoantibodies. Ultrasound showed a heterogenous thyroid with decreased vascularity and Radioactive Iodine Uptake and Scan had less than 5% uptake. Within two months, laboratory tests progressed into the thyroiditis pattern of transient hyperthyroidism followed by hypothyroidism. Based on imaging and laboratory results in conjunction with the clinical progression of our patient, we hypothesize that he developed vaccine-induced thyroiditis. Given the novelty of the COVID-19 vaccine, this hypothesis has yet to be validated by more reports of similar reactions in other patients. Before arriving to this diagnosis, we carefully evaluated for and excluded more common causes of painless thyroiditis including Hashimoto's, Graves' disease, and medication-induced thyroiditis. Interestingly, in recent months there have been reports of two females who developed Graves' disease three days after receiving the Pfizer vaccine (3) and one female who developed Subacute Thyroiditis five days after the same vaccine (16). A possible explanation for this autoimmune reaction is molecular mimicry due to the vaccine's spike glycoprotein having genetic similarities with a human heptapeptide (15). Additionally, this innovative vaccine contains a nanoparticle with polyethylene glycol lipid conjugates that has been reported to cause anaphylaxis and to induce autoimmune responses in susceptible patients (10-14). Although the numbers of CoVID-19 infections, and thus morbidity and mortality from this pandemic, have significantly decreased with vaccination, like with any other vaccine, adverse reactions will occur (17). We believe that as more patients get vaccinated, the data regarding vaccine-induced thyroid disease will increase.