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Guillain-Barré Syndrome (GBS)

Questions & Answers

What is Guillain-Barré syndrome (GBS)?


What causes GBS?


Who is at risk for developing GBS?

Anyone can develop GBS; however, it is more common among older adults. The incidence of GBS increases with age, and people older than 50 years are at greatest risk for developing GBS.

How common is GBS, and how common is it among people who have been vaccinated against seasonal influenza?

GBS is rare. Medical events occur regardless of vaccination, and background rates are used to assess vaccine safety by comparing the expected rate of disease or death to the actual or observed rate in any given timeframe. The background rate for GBS in the U.S. is about 80 to 160 cases of GBS each week, regardless of vaccination.

What happened in 1976 with GBS and the swine flu vaccine?


It is important to keep in mind that severe illness and death are associated with influenza, and vaccination is the best way to prevent influenza infection and its complications.

How do public health authorities investigate cases of GBS?

Ensuring the safety of vaccines is a high priority for CDC. Several systems are in place to monitor vaccine safety. One of these systems is the Vaccine Adverse Event Reporting System (VAERS).

CDC and the U.S. Food and Drug Administration (FDA) co-manage VAERS, which serves as an early warning system to collect voluntary reports about possible side effects that people experience following vaccinations. CDC and FDA scientists regularly review all VAERS reports and store the information in a computerized database that is monitored to detect new, unusual, or rare health events that could be possible side effects of vaccines.

In addition to the normal vaccine safety monitoring systems, CDC has proactively put additional monitoring systems in place to ensure safety after licensing. Some of these systems include: actively observing persons in defined geographic areas, collaborating with professional organizations for reports of any adverse events after vaccination, and conducting thorough investigations when severe adverse events occur to determine whether they may have been associated with the vaccine. Through these numerous approaches, we are able to detect any possible risk of GBS that might be associated with the 2012-2013 flu vaccines as early as possible and take appropriate action.


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