Figure 1.

Patient flow. ^aAmong four reports that were excluded from the study because of missing date of GBS/FS, one report referred to A(H1N1) vaccination. Including this report in a sensitivity SCCS analysis altered the result only marginally. ^bDuplicate reports: Five patients with onset of GBS/FS during the study period were reported twice, each by different participating hospitals. For these patients, the report from the initially treating hospital was included in the analysis. ^cThe “not vaccinated” population contains only reports without A(H1N1) vaccination and without seasonal influenza vaccination in the season 2009/2010. Reports with A(H1N1) and/or seasonal influenza vaccination in 2009/2010 prior to 1 November 2009 were included in the population of “other reports.” ^dOut of these, 362 reports fulfilled the BC case definition (levels 1–3). ^e“Other reports” include one report with A(H1N1) vaccination prior to 1 November 2009, 54 reports with seasonal influenza vaccination prior to 1 November 2009, one report with GBS onset before seasonal influenza vaccination, three reports with unknown month of seasonal influenza vaccination, 20 reports (3.0% of all 676 GBS/FS reports) with unknown vaccination status regarding A(H1N1) and seasonal influenza vaccination, and three reports with unknown vaccination status regarding seasonal influenza vaccination. BC, Brighton Collaboration; FS, Fisher syndrome; GBS, Guillain–Barré syndrome; p.v., post-vaccination