American Journal of Epidemiology — GBS study

Title: Guillain-Barré Syndrome, Influenzalike Illnesses, and Influenza Vaccination During Seasons With and Without Circulating A/H1N1 Viruses

http://aje.oxfordjournals.org/content/174/3/326.full

Excerpt from Discussion: “The present study had the unique advantage of starting long before the A/H1N1 pandemic was announced and in the absence of any alert, and it combined both exhaustive recruitment of cases in the study centers and a case-control analysis. In addition, to our knowledge, it is the sole study on this topic using clinical data where GBS cases have been confirmed. A significantly higher occurrence of GBS was observed during influenza virus circulating periods in 2008–2009 and 2009–2010 than during comparative noncirculating periods. Whether these differences could be attributable to vaccination as opposed to the viral infection itself was studied with the case-control analysis. It also found that subjects with a recent history of influenza or influenzalike symptoms showed higher odds of GBS but that vaccination itself was not associated with significantly elevated odds ratios, regardless of whether the vaccine was seasonal or A/H1N1 vaccine.”