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.