According to preliminary data, the rate of Guillain-Barré Syndrome (GBS) after reciept of 2009 H1N1 vaccine is consistent with seasonal influenza vaccine - 1.92 cases per million people. This rate represents a slight increase from the incidence rate of GBS in the general population, which is 1.22 cases per million. This means that the incidence of GBS for vaccinated people is only about 1 additonal case per million people. The rate of GBS for 2009 H1N1 vaccine is also much lower than the rate of GBS seen during the 1976 swine flu vaccine campaign. According to the report, between October 1, 2009 and May 10, 2010, there were 27 documented cases of GBS within 42 days of vaccination, however direct causality was not established.
While surveillance for adverse events after 2009 H1N1 vaccine will continue, these findings continue to show evidence that the vaccine is safe. The 2009 H1N1 virus strain will be included in this year's seasonal influenza vaccine, which is now recommended "universally" for everyone over six months of age.