DRUG REACTIONS Risk of Guillain-Barre syndrome small after flu vaccine

Results from a US study showed that there was no increased risk of influenza virus vaccine-associated Guillain-Barre syndrome from 1992-1993 to 1993-1994. However, a small risk of developing influenza virus vaccine-associated Guillain-Barre syndrome was seen in both of these time periods.

The number of reports of Guillain-Barre syndrome reported to the US National Vaccine Adverse Event Reporting System increased from 37 in the 1992-1993 influenza vaccination season to 74 in the 1993-1994 season. This increase aroused concern about a possible increase in vaccine-associated risk. In the study, 273 adult patients (62% men; mean age 54 years) diagnosed with Guillain-Barre syndrome during these 2 seasons were identified from hospital discharge data in 4 US states.

Of these 273 patients, 180 (66%) were interviewed. Influenza virus vaccination in the 6 weeks prior to the development of Guillain-Barre syndrome was confirmed in 191180 patients. The relative risk (RR), adjusted for age, gender and vaccine season, for developing Guillain-Barre syndrome was 1.7 (95% CI 1-2.8), equating to just over 1 additional case of Guillain-Barre syndrome per million vaccinations. The RRs (adjusted for age and gender) for the 1992-1993 and 1993-1994 seasons were 2 and 1.5, respectively.

The researchers say that the results of their study suggest that the increase in reports of Guillain-Barre syndrome in the 1993-1994 season was not due to an increase in influenza virus vaccine-specific risk, but probably to an increase in vaccine coverage and in the baseline incidence of the syndrome. Lasky T, TerracciaDo GJ, Magder 1.., Koski CL, Ballesteros M, et al. The Guillain-Bam syndrome and the 1992-1993 and 1993-1994 influenza vaccines. New England Journal of Medicine 339: 1797-1802, 17 Dec 1998 I007302O<

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