Guillain-Barré syndrome after influenza vaccination in the United States, a report from the CDC/FDA vaccine adverse event reporting system (1990-2009).

Objectives: To determine the rate of Guillain–Barre syndrome (GBS) after administration of influenza vaccine in the United States and to provide further information about the characteristics and temporal profile of these incidents. Methods: Data were acquired from the Vaccine Adverse Event Reporting System, supplemented by data from the Center for Biologics and Research under the Freedom of Information Act between 1990 and 2009. Results: There were 802 cases (mean age, 54.72 ± 18.4 years) of GBS reported after influenza vaccination in the United States between 1990 and 2009. Among the 802 vaccinated patients with available data, 624 (77.8%) developed GBS within 6 weeks and 78 (9.7%) after 6 weeks, whereas these data were unavailable for the remaining 100 patients (13%). The reporting rate of post–influenza vaccine GBS was within the range expected in the general population or approximately 0.46 cases per million vaccinations. A non-Gaussian distribution of GBS within the first 6 weeks post-vaccination was noted, given that the peak incidence occurred in the second week. Conclusions: The incidence of post–influenza vaccine GBS is similar to the incidence of idiopathic GBS in the general population. Although the nonnormal distribution of post-vaccination GBS suggests that some cases may be triggered by vaccination, the greater risk of complications from influenza virus infections makes vaccination the first-line strategy for infection prevention and support the current guidelines on vaccination.