ACTA ENDOCRINOLOGICA (BUC)

Context. Subacute thyroiditis, a manifestation of Autoimmune/inflammatory syndrome induced by adjuvants that may develop after vaccination. Objective. The aim of this study is to determine the importance of vaccination against COVID-19 in the etiology of subacute thyroiditis. Design. This case reports/series is an observational, descriptive research design. Subjects and Methods. Five of the thirty patients who applied to our clinic with subacute thyroiditis in the last 6 months had a history of inactivated and mRNA vaccines in the last four weeks, after exclusion of infection and comorbidities. We present three cases of mRNAbased vaccination and two cases of inactive SARS-CoV-2 vaccination that met ASIA criteria. Results. Our findings suggest that subacute thyroiditis may be a complication of vaccination against COVID-19. Conclusion. Vaccine administration may led to autoimmune manifestation induction as well as autoantibody production. Adjuvant-induced autoimmune/inflammatory syndrome, an abnormal autoimmune response as a result of exposure to an adjuvant such as vaccine, appears likely in our cases.