Susac syndrome following COVID-19 vaccination: a case-based review

COVID-19 vaccine circulation approval was a turning point for the coronavirus pandemic. The current approved COVID-19 vaccines, including messenger ribonucleic acid (mRNA)-based and adenovirus vector-based vaccines, were shown to significantly reduce the disease mortality and severity, and its adverse reactions are mainly mild ones. However, few cases of autoimmune conditions, both flare-ups and new-onset, were described in association with these vaccines. Susac vasculitis (SaS) is a rare autoimmune disease characterized by the clinical triad of encephalopathy, visual disturbances, and sensorineural hearing loss. Its pathogenesis is still not fully understood but is believed to be related to autoimmune processes, including autoantibodies to anti-endothelial cells and cellular immune processes that lead to microvascular damage and, consequently, micro-occlusions of the cerebral, inner ear, and retinal vessels. It has been previously described following vaccination and, most recently, few cases following coronavirus vaccines. We here describe a case of a previously healthy 49-year-old man diagnosed with SaS 5 days following the first dose of the BNT162b2 COVID-19 vaccine.