Infections induce activated T cells and antibodies, which within the context of an influenza syndrome, are thought to cross react with axonal antigens and macrophages, resulting in demyelination.This process likely triggers a subsequent Guillain-Barre’ syndrome (GBS).
Presumably, influenza vaccine induces a similar response in susceptible individuals.
Juurlink and colleagues found there to be a 1.45 relative risk, which equals a 1.7-fold adjusted relative risk for contracting GBS, associated with influenza vaccination.
References
P. Haber, et al. Guillain-Barre' Syndrome Following Influenzae Vaccination. JAMA. 2004;292:2478-2481.
Stowe J, et al. Investigation of the temporal association of Guillain-Barré syndrome with influenza vaccine and influenza-like illness using the United Kingdom General Practice Research Database. Am J Epidemiol 2009;169:382-8.
Tam CC, et al. Guillain-Barré syndrome and preceding infection with campylobacter, influenza and Epstein-Barr virus in the general practice research database. PLoS One 2007;2:e344.
