Guillain-Barre Syndrome After COVID-19 Vaccination: A Secondary Analysis of Domestic Safety Data by the Japanese Government.

Purpose The purpose of this study was to figure out the risk of Guillain-Barre syndrome (GBS) after coronavirus disease 2019 (COVID-19) vaccination, which has been reported as a rare adverse reaction. Methods Elucidating the characteristics, we performed a secondary analysis of the cases from February 2020 through January 2022, based on the publicly available spontaneous adverse reaction reports in Japan. Results We identified 115 cases, and all were after messenger RNA (mRNA) vaccination. Of all the cases, 69 (60.0%) were female and 44 (38.2%) were older than 65 years old. Severe GBS was reported by 38 males (median age 61.5 years) and 51 females (median age 55 years). The median interval from vaccination to the onset of symptoms was eight days for males and four days for females. Sequelae were reported in 18 patients (7 males, median age 81 years; 11 females, median age 51 years), 11 of whom were older than 65 years old. The estimated incidence was about 0.0001% (0.000058% for the Pfizer vaccine and about 0.000046% for the Moderna vaccine, respectively). Conclusions Spontaneous reports would have various biases, the incidence of GBS after mRNA vaccination was as low as in other existing vaccination programs, and it is important not to interpret that risk expansively.