Risk of Guillain-Barré Syndrome Following COVID-19 Vaccines: A Nationwide Self-controlled Case Series Study.

Of 58 530 770 people aged 12 years or older, 88.8% received at least one Covid-19 vaccine dose, and 2 229 were hospitalized for GBS during the study period. Patients had a median age of 57 years and were 60% males. The relative incidence of GBS between 1-42 days was 2.5 (95%CI, 1.8 to 3.6) for the first dose of ChAdOx1-S and 2.4 (95%CI, 1.2 to 5.0) for the unique dose of Ad26.COV2.S vaccine. We estimated 6.5 attributable GBS cases per million persons having received a first dose of ChAdOx1-S and 5.7 cases per million for the Ad26.COV2.S vaccine. Except for the 12-49 years age group after the second dose of the mRNA-1273 vaccine (RI; 2.6 [95%CI, 1.2 to 5.5]), none of the relative incidence estimates were found significantly increased for the mRNA vaccines, DISCUSSION: In summary, we found increased risks of Guillain-Barré syndrome following the first administration of ChAdOx1-S and Ad26.COV2.S vaccines. In this comprehensive assessment at the French population level, there was no statistically significant increase in risk of Guillain-Barré syndrome after the administration of mRNA vaccines. This is reassuring in the context of the ongoing and future use of mRNA-based booster vaccination.