COVID-19 vaccine-associated subacute thyroiditis: an unusual suspect for de Quervain's thyroiditis

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.