Background The number of reports of influenza-vaccine-associated Guillain-B
arre syndrome to the national Vaccine Adverse Event Reporting System increa
sed from 37 in 1992-1993 to 74 in 1993-1994, arousing concern about a possi
ble increase in vaccine-associated risk.
Methods Patients given a diagnosis of the Guillain-Barre syndrome in the 19
92-1993 and 1993-1994 influenza-vaccination seasons were identified in the
hospital-discharge data bases of four states. Vaccination histories were ob
tained by telephone interviews during 1995-1996 and were confirmed by the v
accine providers. Disease with an onset within six weeks after vaccination
was defined as vaccine-associated. Vaccine coverage in the population was m
easured through a random-digit-dialing telephone survey.
Results We interviewed 180 of 273 adults with the Guillain-Barre syndrome;
15 declined to participate, and the remaining 78 could not be contacted. Th
e vaccine providers confirmed influenza vaccination in the six weeks before
the onset of Guillain-Barre syndrome for 19 patients. The relative risk of
the Guillain-Barre syndrome associated with vaccination, adjusted for age,
sex, and vaccine season, was 1.7 (95 percent confidence interval, 1.0 to 2
.8; P=0.04). The adjusted relative risks were 2.0 for the 1992-1993 season
(95 percent confidence interval, 1.0 to 4.3) and 1.5 for the 1993-1994 seas
on (95 percent confidence interval, 0.8 to 2.9). In 9 of the 19 vaccine-ass
ociated cases, the onset was in the second week after vaccination, all betw
een day 9 and day 12.
Conclusions There was no increase in the risk of vaccine-associated Guillai
n-Barre syndrome from 1992-1993 to 1993-1994. For the two seasons combined,
the adjusted relative risk of 1.7 suggests slightly more than one addition
al case of Guillain-Barre syndrome per million persons vaccinated against i
nfluenza. (N Engl J Med 1998;339:1797-802.) (C) 1998, Massachusetts Medical
Society.