Endocrine Abstracts

Since the emergence of the Covid-19 pandemic in 2019, a massive vaccination campaign has been undertaken around the world, and SARS-CoV-2 vaccines-induced thyroid diseases became more frequently described in the literature. Subacute thyroiditis is reported in 52 patients, mean age 45.5±1.8 years, mainly in women (n = 39), after the first (62%) or the second (38%) dose of mRNA (60%), inactivated whole-virus (25%) and adenoviral-vectored (13.5%) vaccines. The mean time to onset is 9.0±0.8 days, and the most frequent symptom is neck pain (97%). Thyrotoxicosis is confirmed by increased free T4 (30.0±2.8 pmol/l), free T3 (34.3±10.8 pmol/l) concentrations, with high ESR (53±3 mm/hour) and CRP (105±14 mg/l), heterogeneous thyroid gland with hypoechoic areas and decreased blood flow, decreased uptake on thyroid scan, and in rare patients on post-surgical pathology (n = 1) or on cytology after FNA (n = 5). Patients were initially given NSAIDs (52%) and/or oral glucocorticoids (48%), 10% patients are followed without treatment. In most patients, thyroid function returns to normal and subacute thyroiditis does not relapse. Graves’ disease is more frequent in women (n = 22) than in men (n = 10), mean age 46.2±2.6 years. Hyperthyroidism is reported as new onset, recurrent or exacerbation of well controlled disease, after the first (62%) or the second dose (34%) of mRNA (72%) or adenoviral-vectored (28%) vaccines. Mean time to thyrotoxicosis onset is 15.1±2.6 days and patients present palpitations (53%), weight-loss (34%), tremor (22%). Thyrotoxicosis is confirmed by increased free T4 (43.3±4.0 pmol/l), free T3 (39.0±20.1 pmol/l) concentrations, with positive anti-TSH-receptor or thyroid stimulating immunoglobulins, markedly increased uptake of the radiotracer activity and increased vascularity of normal sized or enlarged thyroid gland. Patients are treated with beta-adrenergic blockers (32%), antithyroid drugs (89%), and 11% have no treatment. The discussed underlying pathogenic mechanisms of SARS-CoV-2 vaccine-induced thyroid diseases are molecular mimicry (SARS-CoV-2 proteins sharing a genetic homology with a large heptapeptide human protein) or autoimmune/inflammatory syndrome induced by adjuvants (ASIA), usually occurring in genetically susceptible individuals. The benefits of SARS-CoV-2 vaccination far weight the potential vaccine-induced side effects, but clinicians should be aware of possible thyroid adverse-effects, and can advise patients to seek medical assistance when experiencing anterior neck pain, fever or palpitations after SARS-CoV-2 vaccination. Further studies are warranted to clarify the clinical features, predisposing factors, management, and to investigate the etiopathogenesis of SARS-CoV-2 vaccines-induced thyroid diseases.