DOI:10.1093/aje/kwn310 Original Contribution Investigation of the Temporal Association of Guillain-Barre ́ Syndrome With Influenza Vaccine and Influenzalike Illness Using the United Kingdom General Practice Research Database

In 1976, the national swine influenza vaccination program in the United States was suspended because of an increased risk of Guillain-Barre ́ syndrome. Subsequent studies of seasonal influenza vaccine have given conflict-ing results. The authors used the self-controlled case series method to investigate the relation of Guillain-Barré syndrome with influenza vaccine and influenzalike illness using cases recorded in the General Practice Research Database from 1990 to 2005 in the United Kingdom. The relative incidence of Guillain-Barre ́ syndrome within 90 days of vaccination was 0.76 (95 % confidence interval: 0.41, 1.40). In contrast, the relative incidence of Guillain-Barre ́ syndrome within 90 days of an influenzalike illness was 7.35 (95 % confidence interval: 4.36, 12.38), with the greatest relative incidence (16.64, 95 % confidence interval: 9.37, 29.54) within 30 days. The relative incidence was similar (0.89, 95 % confidence interval: 0.42, 1.89) when the analysis was restricted to a subset of validated cases. The authors found no evidence of an increased risk of Guillain-Barre ́ syndrome after seasonal influenza vaccine. The finding of a greatly increased risk after influenzalike illness is consistent with anecdotal reports of a preceding respiratory illness in Guillain-Barre ́ syndrome and has important implications for the risk/benefit assessment that would be carried out should pandemic vaccines be deployed in the future. association; Great Britain; Guillain-Barre ́ syndrome; influenza, human; influenza vaccines; safet