Observed versus expected^* analysis for Guillain–Barré syndrome cases reported in the UK according to Brighton Collaboration Diagnostic Level¹⁷

Age group (years)	Report source	Rate per 100 000 person years
		Observed [95%CI]			Expected16
		Level 1–3	Level 1–4	Level 1–5
All ages	Global	0.13 [0.04; 0.34]	0.30 [0.14; 0.57]	0.34 [0.16; 0.62]	1.22
	UK	0.23 [0.03; 0.82]	0.68 [0.25; 1.48]	0.68 [0.25; 1.48]
0–14	Global	0.00 [0.00; 0.19	0.19 [0.04; 0.55]	0.25 [0.07; 0.64]	0.42
	UK	0.00 [0.00; 0.64]	0.42 [0.05; 1.53]	0.42 [0.05; 1.53]
15–24	Global	0.39 [0.11; 1.00]	0.58 [0.21; 1.27]	0.58 [0.21; 1.27]	1.08
	UK	0.50 [0.06; 1.81]	1.00 [0.27; 2.56]	1.00 [0.27; 2.56]

Diagnostic level 1–3: meets the criteria of Guillain–Barré syndrome (GBS).

Diagnostic level 1–4: includes cases with insufficient evidence to meet the criteria of GBS.

Diagnostic level 1–5: all reported cases including those where a diagnosis of GBS can be reasonably excluded.

^*The expected number of adverse events after vaccination was calculated using the following formula: number of expected events (Ne) equals the age-specific background incidence rate (Inc) multiplied by the number of doses of vaccine administered (Nd) (calculated for each age group from the age distribution of all spontaneous reports received until the data lock point where the age was known) multiplied by the pre-determined risk period (Risk period) (Ne = Inc × Nd × Risk period).