In a prospective study assessing the prevalence of serum myelin oligodendrocyte glycoprotein antibody (MOG-Ab) and aquaporin-4 antibody (AQP4-Ab) among 35 patients with clinical optic neuritis and confirmed COVID-19, it was found that serum MOG-Ab and AQP4-Ab were detected in 28.6% (10/35) and 5.7% (2/35) optic neuritis cases after COVID-19 (29). Here, AQP4 is linked to COVID-19.