Abstract
BACKGROUND AND OBJECTIVE: The concern surrounding the association between Guillain-Barré syndrome (GBS) and vaccination has increased with the widespread use of COVID-19 vaccines. The aim of this study was to assess the potential association of GBS with mRNA-based or adenovirus-vectored COVID-19 vaccines. METHODS: Reports of GBS associated with mRNA-based or adenovirus-vectored COVID-19 vaccines were extracted from the WHO pharmacovigilance database, exposure data from the Our World in Data website, and the background rates of GBS from published data. For countries contributing to VigiBase and with available data on COVID-19 vaccine exposure, reporting rates were estimated and observed-to-expected (OE) analyses were performed. RESULTS: A total of 2499 cases were included: 1157 (46.3%) cases with adenovirus-vectored COVID-19 vaccines and 1342 (53.7%) with mRNA-based COVID-19 vaccines. The male-to-female sex ratio was 1.09 and the median (IQR) age was 57 (45-66) years. The reporting rates (95% CI) per 100,000 person-years within the 42-day window were 5.57 (5.13-6.03) for adenovirus-vectored COVID-19 vaccines and 1.39 (1.31-1.47) for mRNA-based COVID-19 vaccines, while the background incidence was 1.2-3.1 per 100,000 person-years. For mRNA-based COVID-19 vaccines, the OE ratio was <1 for both time windows in all European countries and slightly elevated for the 21-day window in the USA. For adenovirus-vectored COVID-19 vaccines, the OE ratio was consistently > 2.0 for all countries. Sensitivity analyses minimally altered these results. CONCLUSIONS: These findings suggest both the absence of safety concern for GBS with mRNA-based COVID-19 vaccines and an increased risk with adenovirus-vectored COVID-19 vaccines. Back to top.