Abstract:

Subacute thyroiditis (SAT) is a self-limiting inflammatory disease. This study aimed to describe the characteristics of coronavirus disease 2019 (COVID-19) vaccine-associated subacute thyroiditis cases. Forty-five patients diagnosed before the pandemic period and 19 patients diagnosed with SAT within three months after the COVID-19 vaccine were included in this retrospective study. Demographic, clinical characteristics, laboratory parameters, and ultrasonography findings of the patients were recorded. In addition, the type of vaccines they received, the time until SAT appeared after vaccination, the treatment given, and the response to treatment were evaluated. The demographics, clinical characteristics, laboratory parameters, and treatments they received were similar between the SAT group (Group-1) (n=19) associated with the COVID-19 vaccine and the SAT group (n=45) (Group-2) detected before the pandemic. Only serum C-reactive protein and mean erythrocyte sedimentation rate were higher in Group-2 than in Group-1 (p <0.05). During follow-up, euthyroid cases were detected in 15/19 (78.9%) and 15/45 (33.3%) in Group-1 and Group-2, respectively (p<0.05). There was no difference in relapse rates. SAT was observed in 7 patients after the inactive COVID-19 vaccine and 12 patients after the mRNA COVID-19 vaccine. The median time to symptom onset after vaccination was 11 (4-45) days. As COVID-19 vaccination rates increased during the pandemic, vaccine-related SAT cases became more common. This study showed that COVID-19 vaccine-associated cases have diagnostic features and clinical courses similar to classical SAT.

Keywords: