SARS-CoV-2 Vaccine–induced Thyroiditis

Safety of Revaccinations and Clinical Follow-up

Seda Hanife Oğuz; Süleyman Nahit Şendur; Burçin Gönül İremli; Alper Gürlek; Tomris Erbas; Uğur Ünlütürk


J Clin Endocrinol Metab. 2022;107(5):e1823-e1834. 

In This Article

Abstract and Introduction


Context: The number of reported cases with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) vaccine–induced subacute thyroiditis (SAT) and Graves' disease (GD) is growing. However, active debate continues about managing such side effects and the safety of repeat or booster doses of the vaccines in such cases.

Objectives: This study aims to present long-term clinical follow-up of SARS-CoV-2 vaccine–induced SAT or GD cases and provide data regarding the safety of revaccinations.

Methods: Patients diagnosed with SARS-CoV-2 vaccine–induced SAT or GD were included. Data regarding the long-term clinical follow-up of SARS-CoV-2 vaccine–induced SAT and GD cases and outcomes of repeat or booster SARS-CoV-2 vaccinations were documented. The literature, including cases of SARS-CoV-2 vaccine–induced SAT or GD, was reviewed.

Results: Fifteen patients with SARS-CoV-2 vaccine–induced SAT and 4 with GD were included. Pfizer/BioNTech COVID-19 vaccine (BNT162b2) was associated with symptoms in a majority of cases with SAT and all with GD. Median time from vaccination to symptom onset was 7 and 11.5 days, respectively, while 7 and 2 patients required medical treatment in SAT and GD groups, respectively. Remission was documented in 10 SAT patients, with a median time to remission of 11.5 weeks. No exacerbation/recurrence of SAT occurred in 7 of 9 patients who received a repeat vaccination dose, while symptoms of SAT worsened following the second vaccination in 2 cases. None of the patients experienced severe side effects that could be associated with revaccinations.

Conclusions: Revaccinations appear to be safe in patients with SARS-CoV-2 vaccine–induced SAT cases, while more evidence is needed regarding SARS-CoV-2 vaccine–induced GD.


The pandemic of the new coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is still ongoing and has affected more than 250 million people, and 5 million were deceased by November 2021. A year after the pandemic began, Phase II/III trials of SARS-CoV-2 vaccinations had been published. Subsequently, COVID-19 immunization programs throughout the globe have started in early 2021, following the emergency use authorization of the vaccines. Inactivated whole virion SARS-CoV-2 vaccines (ie, CoronaVac developed by Sinovac Life Sciences)[1] vaccines using messenger RNA (mRNA) technology and lipid nanoparticle delivery systems (ie, BNT162b2 developed by Pfizer-BioNTech, mRNA-1273 developed by Moderna)[2,3] and vaccines using nonreplicating recombinant adenovirus vector systems (i.e., ChAdOx1 nCoV-19 developed by Oxford-AstraZeneca)[4] are currently available and were all found effective and safe in clinical trials.

It has been hypothesized that SARS-CoV-2 might cause a wide range of autoimmune/autoinflammatory diseases via molecular mimicry, dysregulated immunity in response to COVID-19, or other as-yet-undiscovered pathways.[5] Antibodies against the SARS-CoV-2 spike protein have been shown to cross-react with various human tissue proteins, including thyroid peroxidase.[6] It has been postulated that vaccines against SARS-CoV-2 may also induce autoimmune reactions.[5] mRNA and adenovirus-vectored vaccines encode,[3,4] and the inactivated SARS-CoV-2 vaccines contain[1] the SARS-CoV-2 spike protein, the primary target of neutralizing antibodies generated during natural infection. Therefore, cross-reactivity of the spike protein with thyroid antigens following vaccinations seems possible. Moreover, it has also been proposed that adjuvants found in vaccines might induce autoimmune/inflammatory syndrome in genetically susceptible individuals.[7] Various autoimmune/autoinflammatory events linked to COVID-19 immunization have recently been documented in the literature, corroborating these findings.[8,9] Among all, cases of subacute thyroiditis (SAT)[10–26] have been most commonly encountered in daily practice, and Graves' disease has also been reported.[20,25–34] However, active debate continues among physicians about managing such side effects, particularly the administration and timing of repeated or booster doses of the vaccines in such cases.[35]

Therefore, we present the long-term clinical follow-up of SAT and Graves' disease cases attributable to SARS-CoV-2 vaccinations and the effects of repeat SARS-CoV-2 vaccinations on disease outcomes.