Graves' Disease Following COVID-19 Vaccination.

Autoimmune endocrine diseases have been reported after influenza and the human papillomavirus vaccine, but there is limited data on autoimmune diseases after coronavirus disease 2019 (COVID-19) vaccination. Our report is about a 42-year-old Caucasian male and a 68-year-old Caucasian female who developed Graves' disease after receiving Moderna (Moderna, Inc., Cambridge, Massachusetts, United States) and Johnson & Johnson (Johnson & Johnson, New Brunswick, New Jersey, United States) vaccines, respectively. Both patients had no previous autoimmune thyroiditis and had normal thyroid function but developed hyperthyroidism characterized by suppressed thyroid-stimulating hormone (TSH), elevated free T4 level, and TSH receptor antibodies after vaccination. COVID-19 vaccines, either mRNA-based (Moderna) or non-mRNA-based (Johnson & Johnson), can cause Graves' disease. The clinical manifestations are similar to Graves' disease but without ocular manifestations.