Safety and neutralization antibody levels of inactivated SARS-CoV-2 vaccine in adult patients with Myasthenia Gravis: a prospective observational cohort study.

BACKGROUND AND OBJECTIVES: Myasthenia gravis (MG) is an autoimmune disease affecting the neuromuscular junction. No cohort study has investigated the efficacy of inactivated vaccines in patients with MG. MATERIALS AND METHODS: This prospective observational cohort study included healthy controls (HCs) and patients with MG with or without immunosuppressive treatment. Vaccination occurred between May and December 2021. Patients with MG were subjected to a clinical scale assessment for disease severity. The neutralization antibodies (Nabs) levels were measured in all participants using the pseudovirus neutralization assay. RESULTS: Twenty-one patients (Female/Male:10/11); age median [interquartile range (IQR)]: 43 [30, 56]) were included in this study. Two patients (2/21) were lost during follow-up after enrollment. No sustained vaccine-related adverse effects occurred in any visit of patients with MG. No exacerbation of MG was observed. Acetylcholine receptor antibody (AChR-Ab) levels showed no statistically significant changes between the first and second visit (median [IQR]: 2.22 [0.99, 2.63] nmol/L vs. 1.54 [1.07, 2.40] nmol/L, p = 0.424). However, levels of AChR-Ab decreased at the third visit (median [IQR]: 2.22 [0.96, 2.70] nmol/L vs. 1.69 [0.70, 1.85] nmol/L, p = 0.011). No statistically significant difference in Nabs levels was found between HCs and patients with MG (median [IQR]: 102.89 [33.13, 293.86] vs. 79.29 [37.50, 141.93], p = 0.147). DISCUSSION: The safety of the SARS-CoV-2 inactivated vaccine was reconfirmed in this study. No significant difference in Nabs level was found between patients with MG and HCs. Nabs levels correlated with AChR-Ab levels before vaccination and ΔAChR-Ab levels.