Is there a correlation between MOGAD and SARS-CoV-2 infection?

Background: MOG-Abs distinguish a group of inflammatory disorders which can be preceded by specific or non-specific infections. Few single cases have been reported in association with SARS-CoV-2 infection, but a specific study on the correlation between COVID-19 and MOG-associated disorder (MOGAD) has not been performed, yet. Aim of this study is to determine the impact of the pandemic on this condition. Methods: We analysed SARS-CoV-2 serology in newly diagnosed MOG-Abs patients (August 1st 2020-May 31st 2021). MOG-Ab seronegative age and time-matched subjects were used as controls. SARS-CoV-2 IgG were analysed using an anti-SARS-CoV-2 FDA-approved ELISA assay (Euroimmun, Luebeck, Germany) and confirmed with a trimeric anti-SARS-CoV-2 S1/S2 IgG immunochemiluminescent test (DiaSorin), concomitantly assaying anti-Receptor Binding Domain (RBD) of spike protein (Beckman) IgG and anti-RBD total Ig (Roche). We then compared the number of cases referred in the last 3 years. Results: SARS-CoV-2 IgG were more common (12/30, 40%) in MOGAD than in controls (6/30, 20%), although the difference was not significant (p=0.16; OR=2.67, 95% CI 0.85-9.17). The most common clinical presentations of MOGAD SARS-CoV-2 seropositive cases included optic neuritis (n=6) and myelitis (n=3). The number of diagnosed cases increased in the last 3 years, in particular, when including cases referred before the COVID-19 pandemic, in the initial phase of the first wave and in the late phase of the second wave (n=9, rate 10.6% in 2019; n=13, rate 12.3% in 2020; n=and 15, rate 14.7% in 2021). Conclusion: Our findings provide preliminary data on SARS-CoV-2 as a potential trigger of MOGAD.