Thyroiditis after Coronavirus Disease 2019 (COVID-19) mRNA Vaccine: A Case Series

Thyrotoxicosis with palpitation, and neck tenderness is the most common presentation of thyroiditis. The patients with new onset of thyrotoxicosis should be asked about history of mRNA-vaccine injection for the possible etiology.

mRNA vaccine induced thyroiditis could occur 10-20 days after the first dose or the second dose.

Management is to relieve the symptom of tachycardia with beta-blocker and neck pain with NSAIDS. Glucocorticoid steroid is used with caution or avoided when possible because of the concern about interfere with vaccination induced protective antibody production.

It is unclear whether mRNA vaccine induced thyroiditis is age-related, although all three cases are at middle-age.

While SARS-COV-2 virus infection was reported to cause subacute thyroiditis, the mRNA vaccine for SARS-COV-2 was suspected to induce thyroiditis with thyrotoxicosis.

Case Report
We describe three patients without a history of thyroid disease who presented with symptomatic, biochemical, and radiological evidence of thyroiditis with thyrotoxicosis, 10-20 days after receiving either the Pfizer Bio-NTech or the Moderna COVID-19 mRNA vaccine. All presented with thyrotoxicosis, but with negative thyroid stimulating immunoglobulins for Graves’ disease and no autonomous nodules. Two patients underwent thyroid uptake and scan which confirmed thyroiditis. One patient had significantly increased erythrocyte sedimentation rate (ESR) and Interleukin-6 (IL-6). All had improvement in symptoms with non-steroidal anti-inflammatory drugs (NSAIDs), with one patient eventually requiring steroids for symptom control.

The mRNA vaccine for SARS-COV-2 was associated with thyroiditis and presented with thyrotoxicosis. Elevated proinflammatory markers and cytokines after vaccines may play a major role.

Our case series report highlights a possible relationship between the COVID-19 mRNA vaccine and thyroiditis with thyrotoxicosis, which previously not recognized by health providers.