Thyrotoxicosis in patients with a history of Graves’ disease after SARS-CoV-2 vaccination (adenovirus vector vaccine): Two case reports

BACKGROUND: Vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) which were approved for emergency use have been administered on a large scale globally to contain the pandemic coronavirus disease 2019 (COVID-19) and to save lives. Vaccine safety is one of the issues under surveillance and a possible correlation between vaccines and thyroid function has been reported. However, reports of the impact of coronavirus vaccines on those with Graves’ disease (GD) are rare. CASE SUMMARY: This paper presents two patients with underlying GD in remission, both developed thyrotoxicosis and one developed thyroid storm following the adenovirus-vectored vaccine (Oxford-AstraZeneca, United Kingdom). The objective of this article is to raise awareness regarding a possible association between COVID-19 vaccination and the onset of thyroid dysfunction in patients with underlying GD in remission. CONCLUSION: Receiving either the mRNA or an adenovirus-vectored vaccine for SARS-CoV-2 could be safe under effective treatment. Vaccine induced thyroid dysfunction has been reported, but the pathophysiology still not well understood. Further investigation is required to evaluate the possible predisposing factors for developing thyrotoxicosis especially in patients with underlying GD. However, early awareness of thyroid dysfunction following vaccination could avoid a life-threatening event.