Table 4. Relative incidence estimates for the association between infections, influenza A(H1N1)pdm09 vaccination, seasonal influenza vaccination and Guillain-Barré syndrome.
DK | FI | FR | NL | NO | SE | UK | Pooled | |||||||||
RI | 95% CI | RI | 95% CI | RI | 95% CI | RI | 95% CI | RI | 95% CI | RI | 95% CI | RI | 95% CI | RI | 95% CI | |
Covariates | ||||||||||||||||
ILI | NA | NA | NA | 10.5 | 3.0–36.3 | 30.6 | 8.6–108 | NA | 1.8 | 0.2–16.0 | 10.4 | 2.6–41.1 | ||||
URTI | NA | NA | NA | 13.0 | 4.3–39.2 | 17.7 | 6.2–34.7 | NA | 2.2 | 0.4–10.6 | 8.51 | 3.0–24.0 | ||||
GI | NA | NA | NA | 11.6 | 2.8–49.4 | 53.31 | 6.56–433 | NA | 2.3 | 0.2–22.6 | 11.9 | 2.5–55.6 | ||||
Seasonal influenza vaccination | NA | NA | NA | 1.2 | 0.4–4.0 | 5.5 | 1.6–18.9 | NA | 6.0 | 1.8–19.7 | 3.9 | 1.8–8.3 | ||||
Any influenza A(H1N1)pdm09 vaccination | ||||||||||||||||
Unadjusted | 7.7 | 1.1–54.4 | 1.6 | 0.5–5.4 | 6.4 | 1.0–40.4 | 2.7 | 1.3–5.9 | 3.9 | 1.6–9.3 | 4.8 | 2.1–11.1 | 3.3 | 0.3–36.5 | 3.5 | 2.2–5.5 |
Adjusted for calendar month | 3.9 | 0.5–32.2 | 1.6 | 0.5–5.4 | 2.9 | 0.4–19.6 | 1.4 | 0.6–3.4 | 1.9 | 0.7–5.2 | 2.7 | 1.0–7.8 | 2.3 | 0.2–27.7 | 2.0 | 1.2–3.1 |
Adjustment effect any influenza A(H1N1)pdm09 vaccination in NL, NO, UK | ||||||||||||||||
Adjusted for calendar month only | 1.4 | 0.6–3.4 | 1.9 | 0.7–5.2 | 2.3 | 0.2–27.7 | 1.7 | 0.8–3.4 | ||||||||
Fully adjusted (month, ILI/URTI, GI) | 1.2 | 0.5–3.3 | 1.5 | 0.5–4.6 | 1.5 | 0.1–23.1 | 1.4 | 0.7–2.8 | ||||||||
Sensitivity analysis on influenza A(H1N1)pdm09 vaccination for contra-indication | ||||||||||||||||
Pseudolikelihood | ||||||||||||||||
1st dose | 3.6 | 0.4–29.5 | 3.2 | 0.7–14.6 | 0.6 | 0.1–6.7 | 1.3 | 0.4–4.0 | 1.6 | 0.6–4.3 | 2.4 | 0.8–6.9 | 4.8 | 0.3–83.9 | 1.9 | 1.1–3.2 |
2nd dose | NA | NA | 2.2 | 0.2–26.3 | 1.2 | 0.4–3.4 | NA | NA | NA | 1.3 | 0.5–3.4 | |||||
Vaccinated cases only | NE | 2.6 | 0.2–32.5 | NE | 1.2 | 0.2–8.3 | 1.6 | 0.3–7.9 | 2.5 | 0.4–16.0 | NE | 1.8 | 0.7–4.7 |
Abbreviations: NA: not available or not valid; NE = Not estimable due to small numbers or absence RI: relative incidence; ILI: influenza like illness; URTI: upper respiratory tract infection, GI: gastrointestinal Infection, UK: United Kingdom; NL: Netherlands; FR: France; SE: Sweden; FI: Finland, NO: Norway, DK: Denmark.