Context
SARS-CoV-2 infection and Covid-19 vaccines have been associated with thyroid disorders.
Objective
We analyzed the risk of Thyroid Eye Disease (TED) following Covid-19 vaccination.
Design
Self-controlled case series study.
Setting
Tertiary referral center for TED.
Participants
A total of 98 consecutive patients with newly-developed (N = 92) or reactivated (N = 6) TED occurring between January 1, 2021, and August 31, 2022.
Intervention
Assessment of TED in patients undergoing Covid-19 vaccination.
Main Outcome Measures
Person-days were defined as exposed if TED occurred 1-28 days after vaccination, and unexposed if occurring outside such time-window. Conditional Poisson regression models were fitted to calculate incidence-rate-ratio (IRR), and 95% confidence-intervals (95%CI) of exposed vs unexposed. Sensitivity analyses were conducted considering different exposed periods and effect modification by potential TED risk factors.
Results
Covid-19 vaccines were administered in 81 subjects, 25 (31%) of whom developed TED in exposed, and 56 (69%) in unexposed periods. The IRR for TED was 3.24 (95%CI 2.01-5.20), and 4.70 (95%CI 2.39-9.23) in patients below 50 years of age. Sex, smoking, and radioiodine treatment did not modify the association between TED and vaccination. TED risk was unrelated to the number of vaccine doses, and progressively decreased over time following vaccination (P-trend = 0.03).
Conclusions
The risk of TED was significantly increased after Covid-19 vaccination, especially in subjects below 50 years of age. Possible mechanisms include spike protein interaction with ACE-II receptor, cross-reactivity with thyroid self-proteins, and immune reactions induced by adjuvants. We suggest monitoring of individuals undergoing Covid-19 vaccination, especially if young and at risk for autoimmunity.
