To investigate the association between Guillain-Barré Syndrome (GBS) and influenza vaccination in adults.

There have been isolated cases of GBS after influenza vaccination.

There were 1351 cases of GBS (mean age 55.66±16.33 years, 54.11% men) reported following influenza vaccination between 1990 and 2016. The reporting rate of post-influenza vaccination GBS was approximately 8 cases per 10 million vaccination which is less than the range expected in the general population (0.16-3 cases per 100,000). Of these cases, 1163 (83%) were reported within six weeks after vaccination, with 737 (63.37%) of these reported in the first two weeks. Case-centered Analysis demonstrated that more than 1061 (78.53%) of total GBS cases were reported within the risk period. Of all cases of GBS, only 43 fulfilled the Brighton criteria for levels 1-3: 31 (90%) cases fell within the risk period.

Although we did not observe an increase in the reporting rate of GBS after influenza vaccination as compared to the general population, the unbalanced distribution of cases within the first 6 weeks suggest that some cases are triggered by vaccination. Furthermore, case-centered analysis demonstrated that the majority of GBS cases were reported within the six-week risk period. These results warrant to continue passive and active surveillance and careful evaluation of patients with signs and symptoms of GBS following the influenza vaccination.