Comparison 8. Serious adverse events: Guillain‐Barré syndrome ‐ case‐control studies.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 2009 to 2010 A/H1N1 ‐ general population (unadjusted data)	6		Odds Ratio (M‐H, Random, 95% CI)	Subtotals only
1.1 < 7 weeks	6	1528	Odds Ratio (M‐H, Random, 95% CI)	2.22 [1.14, 4.31]
1.2 At any time	6	1656	Odds Ratio (M‐H, Random, 95% CI)	1.69 [0.87, 3.29]
2 2009 to 2010 A/H1N1 ‐ general population (adjusted data)	4		Odds Ratio (Random, 95% CI)	0.83 [0.39, 1.75]
2.1 < 7 weeks	4		Odds Ratio (Random, 95% CI)	0.92 [0.35, 2.40]
2.2 > 6 weeks (i.e. at any time)	3		Odds Ratio (Random, 95% CI)	0.71 [0.22, 2.32]
3 Seasonal influenza vaccination general population (adjusted data)	1		Odds Ratio (Random, 95% CI)	1.38 [0.18, 10.43]