Covid vaccine induced subacute thyroiditis

ABSTRACT

Effects of Covid19 vaccine (authorized by the Food and Drug Administration and manufactured by Pfizer-BioNTech, Moderna) on thyroid are still not reported. We present two cases of healthy middle aged south Asian patients who developed hyperthyroidism symptoms and confirmed as subacute thyroiditis (SAR) following the administration of COVID 19 (mRNA) vaccines within 2-6 weeks. Interestingly, both of them received PfizerBioNTech vaccine CASE 1 A 35 year-old male with Past Medical History (PMH) of seasonal allergies with palpitations and neck pain 10 days after receiving first dose of Pfizer-BioNTech vaccine. Initial labs after 2 weeks of vaccination showed biochemical hyperthyroidism. Repeat labs trended down. DOSE -1 03/26/21, DOSE -2 04/18/21 TEST DATE 04/13/21 TSH (0.450- 4.50uIU/mL) - 0.07uIU/mL , Free T 4 (0.82-1.77ng/dL4) - 3.04ng/dl, TotalT3 (71 - 180ng/dl) - 200ng/dl, TPO(Thyroid Peroxidase) - negative, TSI(Thyroid Stimulating immunog lobulin) - negative, Thyroid Ultrasound - No nodules 04/22/21 TSH - 0.012uIU/mL, Free T 4 - 2.11ng/dl, TotalT3-198ng/dl CASE 2 A 41 year old female with unremarkable PMH was referred by Primary care physician(PCP) for evaluation of secondary amenorrhea and infertility. She did receive her second dose of PfizerBioNTech vaccine 4 weeks prior. Initial work up confirmed biochemical hyperthyroidism. Repeat tests 4 weeks later trended down with clinial improvement of symptoms. DOSE -1 12/2020, DOSE -2 01/2021 TEST DATE 02/21 TSH-0.019uIU/mL, Free T4 - 2.52ng/dl, TotalT3-233ng/dl 03/21 TSH- 0.006uIU/mL, Free T4 -3.06ng/dl TotalT3- 257ng/dl . TPO -negative, TSI - negative, Thyroid Ultrasou nd - No nodules, Technetium-99m pertechnetate uptake scan - decreased radio tracer uptake in both the lobes of the thyroid gland. 04/21 TSH - 0.020uIU/mL, Free T 4 - 1.51ng/dl, TotalT3-102ng/dl The mechanism of SAR induced by mRNA covid19 vaccine still remains unclear Some unique characteristics seen in this case study -Incidence - in young and middle age group, both male and female got affected -Ethniciity - both are of South Asian ethnicity -Never had COVID infection in the past -Seen with both the first dose and second dose of vaccination The cross recognition between the coronavirus spike protein targeted with the mRNA vaccine and healthy thyroid cell antigen exists as evidenced by this case. Hence association of COVID vaccination with SAT should be considered as a significant addition to literature.