Influenza Vaccine May Protect Against Guillain-Barré Syndrome

Lara C. Pullen, PhD

January 15, 2015

Influenza vaccination reduces the risk for Guillain-Barré syndrome (GBS), a new simulation study suggests.

Steven Hawken, MSc, from the Institute for Clinical Evaluative Sciences in Toronto, Ontario, Canada, and colleagues published the results of their modeling study online January 14 in Emerging Infectious Diseases. The study was designed to evaluate the complex relationship between GBS risk and influenza vaccination and influenza illness. The model focused on individual risk, but the investigators extrapolated the results to include the population health perspective.

Previously published studies have separately evaluated the risk that a patient who receives the seasonal influenza vaccine or contracts influenza will be diagnosed with GBS from influenza. The current study is distinctive because the investigators modeled excess risk for GBS over a wide range of scenarios. The calculated excess risk is therefore sensitive to the estimated combined effect of vaccination, as well as influenza illness.

Dr. Hawken and colleagues found that influenza vaccination reduces individual risk for GBS for most patients under typical conditions (vaccine effectiveness, >60%; influenza incidence rates, >5%).

Exceptions to the rule of protection were predicted in conditions of low vaccine effectiveness and/or low influenza incidence. The authors explain in their article that efficacy of a vaccine will vary by year and region and is dependent on the antigen match between the circulating virus strains and the vaccine.

The model showed a small reduction in absolute risk of GBS with vaccination compared with no vaccination for a hypothetical 45-year-old woman (−0.36/1 million vaccinations; 95% credible interval, −1.22% to 0.28%), as well as for a hypothetical 75-year-old man (−0.42/1 million vaccinations; 95% credible interval, −3.68% to 2.44%).

"[T]he tendency of influenza vaccination to reduce a person’s overall risk of acquiring GBS under many conditions (although the absolute risk differences are extremely small) should strengthen confidence in the safety of influenza vaccination and allow health professionals to better put the risk of GBS in context when communicating risks and benefits to potential vaccinees."

One coauthor has received an investigator-initiated grant from the Canadian Association for Immunization Research and Evaluation, which receives funding from Pfizer.

Emerg Infect Dis. Published online January 14, 2015. Full text

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