Background: Guillain-Barré syndrome (GBS) has been reported to be potentially related to Covid-19 vaccines.
Objectives: We aimed to quantify the population risk of GBS following Covid-19 vaccination according to the type of vaccine.
Methods: During the study period from December 27, 2020 to May 20, 2022, 130 million doses of four vaccines (BNT162b2:107 million, mRNA-1273: 23, ChAdOx1: 7.7, and Ad26.COV2.S: 1.0) were administered in France to people aged 12 years or older. Using comprehensive nationwide hospital discharge and vaccine databases, we analysed all 2 229 individuals admitted for a GBS in the period. We estimated the relative incidence of GBS in the 1 to 42 days after vaccination compared to baseline periods using a self-controlled case series design. We then derived the number of excess cases attributable to the vaccination. Analyses were adjusted for seasonality and stratified by age group, gender, and for the presence of SARS-CoV-2 or common acute infections within 42 days of GBS.
Results: The overall study population had a median age of 57 years and comprised 60% male patients. The median length of stay at hospital was 12 days and 16% of patients were admitted to an intensive care unit. The relative incidence (RI) of GBS between days 1 to 42 compared to the control period was 2.5 (95%CI, 1.8 to 3.6) for the first dose of ChAdOx1 and 2.4 (95%CI, 1.2 to 5.0) for the unique dose of Ad26.COV2.S vaccine. We found a trend toward a raised incidence of GBS between days 15 to 28 after the first dose of mRNA-1273 (RI, 2.0 [95%CI, 0.98 to 3.9]) and BNT162b2 (RI, 1.4 [95%CI, 0.98 to 1.9]) vaccines. There was no significant increase after the second or third doses of the mRNA-based vaccines. The fraction of GBS cases attributable to the vaccination was estimated at 61% (95%CI, 44 to 72) for ChAdOx1 vaccine and 59% (95%CI, 15 to 80) for Ad26.COV2.S vaccine. This translates to 6.5 excess GBS cases per million persons having received a first dose of ChAdOx1 vaccine and 5.7 excess events per million persons receiving the Ad26.COV2.S vaccine.
Conclusions: In summary, we found increased risks of GBS following the administration of ChAdOx1 and Ad26.COV2.S vaccines and no real evidence of risk after the mRNA vaccines. The absolute risk attributable to the vaccination, assuming a causal effect, was in the order of 6 cases per million persons. Owing to the current use of mRNA-based booster vaccination, our results are reassuring regarding the ongoing risk of vaccine-associated GBS.
