"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."
