Dear Editor,

Giant cell arteritis (GCA) is a systemic vasculitis characterized by the disruption of the internal elastic lamina and luminal obstruction [1]. The pathogenesis of GCA is not completely understood but the immune response seems to play a key role in inflammation. In South Korea, there has been a reported case of an 87-year-old woman who presented with bilateral anterior ischemic optic neuropathy from GCA 1 day after receiving the first dose of the Pfizer-BioNTech COVID-19 vaccine (Pfizer Inc) [2].

Here, we present a case of a 77-year-old female patient who developed GCA 17 days after she received her second dose of COVID-19 Pfizer-BioNTech BNT162b2 mRNA vaccine (Pfizer Inc). Written informed consent for publication of the research details and clinical images was obtained from the patient.

The patient was being medicated for type 2 diabetes mellitus and dyslipidemia and had undergone bilateral cataract surgery. After being vaccinated, she presented with decreased visual acuity of left eye, bilateral temple pain, and jaw claudication. Laboratory workup revealed elevated inflammatory markers, with C-reactive protein of 14.7 mg/L and erythrocyte sedimentation rate of 116 mm/hr. Her uncorrected visual acuity (UCVA) was 20 / 50 in the right eye and counting fingers in the left eye. Dilated fundus examination revealed a cherry-red spot and cattle trucking of arterioles in the left eye (Fig. 1A). Optical coherence tomography showed diffuse edema of the inner retina layer of the left eye (Fig. 1B, 1C) The fluorescein angiography exhibited markedly delayed retinal and choroidal prefusion in the left eye (Fig. 1D, 1E) Severe stenosis in the proximal right ophthalmic artery, complete occlusion of the left ophthalmic artery, and multifocal severe stenosis and beading of the left superficial temporal artery were confirmed by transfemoral cerebral angiography (Fig. 1F-1H), while there were no intracranial lesions. The result of left superficial temporal artery biopsy was consistent with GCA (Fig. 1I, 1J). After treatment with intravenous methylprednisolone 1 g daily for 3 days, left UCVA remained hand movements, but other systemic symptoms were resolved. After intravenous steroid pulse therapy, oral prednisolone was started at 60 mg/day and tapered off gradually. Her inflammatory markers also returned to the normal range within a month.

According to the reported literature, approximately 14 cases of GCA occurring after COVID-19 vaccination have been documented worldwide, with symptoms appearing on average 3 days (range, 1-10 days) after vaccination and an average of 6 weeks (range, 3-16 weeks) required for a diagnosis [3]. The adverse events following the first dose of messenger RNA (mRNA) vaccines are primarily driven by innate immune activation and the induction of adaptive immune responses, including memory T- and B-cell formation. The following mechanisms can explain the autoimmune responses after the second dose of mRNA-based vaccine. The second dose of mRNA vaccines is designed to boost the immune response by stimulating the maturation of dendritic cells and eliciting strong T- and B-cell activation. During this process, bystander T-cell activation may occur, potentially triggering autoimmune reactions. The mRNA vaccines are recognized by RNA sensors such as Toll-like receptors (TLR7 and TLR8), leading to the production of type I interferons and proinflammatory cytokines, which could nonspecifically activate autoreactive lymphocytes [4]. Additionally, the presence of vaccine components, such as polyethylene glycol, may induce hypersensitivity and aberrant antigen presentation pathways involving nonclassical antigen-presenting molecules. Furthermore, molecular mimicry between vaccine-induced antibodies and self-antigens could result in cross-reactivity, exacerbating autoimmune inflammation [5].

Although the global pandemic caused by the COVID-19 virus ended, the benefits of vaccination and risks of dysregulation of the immune system after vaccination need to be further researched. Also, it is considered necessary to suspect GCA in cases of retinal artery occlusion or ischemic optic neuropathy occurring after COVID-19 vaccination.