Patients with Hashimoto's thyroiditis present higher immune response to COVID-19 mRNA vaccine compared to normal individuals

Aim: To evaluate the response (titers of anti-COVID-19 antibodies) to COVID-19 mRNA vaccine of patients with Hashimoto's thyroiditis and normal individuals.

Patients and methods: Twenty-four patients with Hashimoto's thyroiditis and 51 normal individuals were studied after the third dose of the vaccine.

Results: Patients with Hashimoto's thyroiditis showed significantly higher immune response after the third dose of the COVID-19 mRNA vaccine compared with normal individuals (p = 0.020). After elimination of the four smokers with Hashimoto's thyroiditis, the immune response between the remaining 20 non-smoking patients compared with the response of the 23 non-smoking normal individuals was not different (p = 0.564). There was a significant positive correlation of the anti-COVID-19 antibodies with BMI (p = 0.029) but not with waist circumference in the patients with Hashimoto's thyroiditis (p = 0.054). Similar correlations were not found in normal individuals. Waist circumference could be considered as representative of visceral adipose tissue. In obese normal individuals (BMI ≥ 30), anti-COVID-19 antibodies were not different from those in lean normal individuals (BMI < 25). In obese patients with Hashimoto's thyroiditis, anti-COVID-19 antibodies were significantly higher compared to those in lean patients (p = 0.013). Median anti-COVID-19 antibody titer in obese patients with Hashimoto's thyroiditis was also significantly higher compared to that in obese normal individuals (p = 0.009).

Conclusions: Patients with Hashimoto's thyroiditis show significantly higher immune response after the third dose of the COVID-19 mRNA vaccine compared with normal individuals. Obese patients with Hashimoto's thyroiditis show additionally a significantly higher immune response compared with lean patients.