Subacute thyroiditis after SARS-CoV-2 BNT162b2 vaccine in a multiple myeloma patient.

Viral infections emerge in the pathogenesis of subacute thyroiditis. Aside from this, subacute thyroiditis following vaccines utilizing inactivated viruses has been shown on rare occasions. Due to the COVID-19 pandemic, several vaccines have been developed all over the world; mass and unprecedented vaccination has thus been initiated. However, it is known that cases such as subacute thyroiditis have been reported, albeit rarely, after administration of COVID-19 vaccines. In this case report, we present a 59-year-old patient with multiple myeloma developing subacute thyroiditis following BNT162b2 vaccine. Patient had swelling in the neck, and his symptoms were controlled with non-steroidal anti-inflammatory drugs. Subacute thyroiditis following administration of the COVID-19 vaccine is rare; however, it is likely an under-reported condition that is difficult to detect. Clinicians should stay informed and have increased awareness of post-COVID-19 vaccine subacute thyroiditis.