Abstract
Subacute thyroiditis following vaccination is an uncommon presentation of thyrotoxicosis. As the world undertakes its largest immunisation campaign to date in an attempt to protect the population from COVID-19 infections, an increasing number of rare post vaccine side effects are being observed. We report a case of a middle-aged woman who presented with painful thyroid swelling following the second dose of the COVID-19 mRNA vaccine BNT162b2 (Pfizer-BioNTech) with clinical, biochemical and imaging features consistent with destructive thyrotoxicosis. Symptomatic management only was required for the self-limiting episode. Thyroiditis typically has a mild and self-limiting course and thus this observation should not deter people from vaccination, as COVID-19 infection has a far greater morbidity and mortality risk than thyroiditis.