Silent thyroiditis following vaccination against COVID-19: report of two cases

PURPOSE: It is well established that thyroiditis and other thyroid disorders can be induced by COVID-19 infection, but there is limited information about the autoimmune/inflammatory syndrome induced by adjuvants (ASIA) after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination. We report two cases of thyrotoxicosis following SARS-CoV-2 vaccine. METHODS AND RESULTS: Two young health care peoples (wife and husband) received a first dose of SARS-CoV-2 vaccine, and few weeks later developed clinical manifestations of thyroid hyperactivity, with increased thyroid hormone levels on thyroid function tests, suppressed thyroid-stimulating hormone and negative antithyroid antibodies, despite being healthy before vaccination. They were diagnosed at the 4th week after first dose of SARS-Cov-2 vaccine as silent thyroiditis and followed without treatment, since their symptoms were not severe. At the 6th week, the patients became wholly asymptomatic and their thyroid function returned to normal. CONCLUSIONS: Thyrotoxicosis can occur after SARS-CoV-2 vaccination probably related to silent thyroiditis.