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Volume 21, Number 2—February 2015
Research

Simulation Study of the Effect of Influenza and Influenza Vaccination on Risk of Acquiring Guillain-Barré Syndrome

Steven Hawken, Jeffrey C. Kwong, Shelley L. Deeks, Natasha S. Crowcroft, Allison McGeer, Robin Ducharme, Michael A. Campitelli, Doug Coyle, and Kumanan WilsonComments to Author 
Author affiliations: Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada (S. Hawken, J.C. Kwong, R. Ducharme, M.A. Campitelli, K. Wilson); Ottawa Hospital Research Institute, Ottawa, Ontario, Canada (S. Hawken, R. Ducharme, K. Wilson); University of Ottawa, Ottawa (S. Hawken, D. Coyle, K. Wilson); Public Health Ontario, Toronto (J.C. Kwong, S.L. Deeks, N.S. Crowcroft); Dalla Lana School of Public Health, University of Toronto, Toronto (J.C. Kwong, S.L. Deeks, N.S. Crowcroft, A.J. McGeer); University of Toronto, Toronto (J.C. Kwong, N.S. Crowcroft, A.J. McGeer)

Main Article

Table 2

Excess risk for GBS per million influenza vaccinations overall and for males and females separately by various influenza incidence rates in a simulated study*

Age, y, sex ∆GBS risk (95% CrI), % ΔGBS risk <0, by influenza incidence rate†
2% 5% 10% 15% 20%
45
Both 0.49 (−0.03 to 1.35), 3.5(+) 0.12 (−0.55 to 0.93), 35.7(±) −0.48 (−1.63 to 0.37), 87.1(−) −1.08 (−2.79 to −0.07), 98.2(−) −1.69 (−3.99 to −0.43), 99.7(−)
F 0.37 (−0.02 to 1.01), 3.5(+) 0.09 (−0.41 to 0.70), 35.6(±) −0.36 (−1.22 to 0.28),‡ 87.0(−) −0.82 (−2.09 to −0.05), 98.2(−) −1.28 (−2.98 to −0.33), 99.7(−)
M
0.66 (−0.05 to 1.79), 3.5(+)
0.16 (−0.74 to 1.24), 35.6(±)
−0.65 (−2.16 to 0.50), 87.1(−)
−1.46 (−3.69 to −0.09), 98.1(−)
−2.28 (−5.27 to −0.59), 99.7(−)
75
Both 0.90 (0.19 to 2.71), 2.2(+) 0.43 (−0.79 to 2.20), 22.6(+) −0.31 (−2.58 to 1.74), 64.7(±) −1.07 (−4.55 to 1.51), 82.6(−) −1.84 (−6.60 to 1.38), 89.3(−)
F 0.69 (0.02 to 2.18), 2.3(+) 0.32 (−0.61 to 1.77), 22.6(+) −0.23 (−2.06 to 1.37), 64.7(±) −0.80 (−3.67 to 1.16), 82.5(−) −1.39 (−5.33 to 1.05), 89.3(−)
M 1.23 (0.02 to 3.90), 2.3(+) 0.58 (−1.09 to 3.15), 22.6(+) −0.42 (−3.68 to 2.44),‡ 64.8(±) −1.44 (−6.54 to 2.09), 82.6(−) −2.48 (−9.47 to 1.89), 89.2(−)

*Assuming vaccine effectiveness of 61% for 45-year-old persons and 50% for 75-year-old persons. Assuming semi-additive effect whereby those vaccinated and who experience influenza illness experience the sum of the 2 relative risks (RR) (i.e., influenza illness RR = 15.81 + 1.52 = 17.33). A total of 1,000,000 simulations were conducted for each scenario. GBS, Guillain-Barré syndrome. Explanations for superscript symbols: (+) <25% of estimates have ∆GBS <0 (favors vaccination increasing GBS risk); (±) 25%–75% of estimates have ∆GBS <0 (neutral); (−) >75% of estimates have ∆GBS <0 (favors vaccination decreasing GBS risk).
†Absolute risk difference between vaccinated and unvaccinated persons. Negative values for ∆ GBS indicate net reduction in no. of GBS cases in vaccinated vs. unvaccinated persons. The % of ∆GBS <0 is the percentage of simulation results where the absolute risk difference for vaccinated vs. unvaccinated was <0 (i.e., protective).
‡Base-case analyses.

Main Article

Page created: January 20, 2015
Page updated: January 20, 2015
Page reviewed: January 20, 2015
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