ABSTRACT
Introduction: Anti-NMDAR encephalitis is an autoimmune neurological disease characterized by the presence in the cerebrospinal fluid (CSF) of antibodies targeting the GluN1 subunit of the N-methyl D-aspartate receptors (NMDAR) in the brain. This study assessed the putative link between anti-NMDAR encephalitis and COVID-19 vaccination. Material and methods: All Individual Case Safety Reports (ICSRs) of anti-NMDAR encephalitis with Tozinameran (Comirnaty®) vaccine and registered in the World Health Organization global database (VigiBase®) up to December 31, 2021, were analyzed. A description and a disproportionality analysis were conducted, using the MedDRA reaction term "Anti-NMDA receptor encephalitis". The reported odds ratio (ROR) and its 95% 2-sided confidence interval have been calculated to compare the proportion of anti-NMDAR encephalitis reports with the suspected vaccine and the proportion of reports of the same adverse drug reaction with all other suspected drugs in the database during the same period. Results: Among the 662 168 ICSRs associated with the suspected vaccine, 3 were anti-NMDAR encephalitis. One of the patients was male (15 years old) and two were female (26 and 69 years old). All cases were serious and required hospitalization. One of those three patients died. The time to onset of anti-NMDAR encephalitis after vaccination was variable and differed between patients (from 2 to 98 days). ROR was significant [2, 95% CI (1.2;2.8)]. Discussion/Conclusion: Several cases of anti-NMDAR encephalitis have been described in the literature after vaccination. This study found a signal between the occurrence of anti-NMDAR encephalitis and Tozinameran. There are currently no available data regarding the potential implication of the vaccines against COVID-19 in the onset of autoimmune encephalitis. The exhaustive recording of anti-NMDAR encephalitis occurring after vaccines is necessary.