Table 4.

Influenza A(H1N1)-vaccinated cases (BC levels 1–3): unadjusted SCCS analyses stratified for age, sex, preceding infection, and BC level

Factor	Influenza A(H1N1)-vaccinated cases in risk period (days 5–42)	Influenza A(H1N1)-vaccinated cases in control period (days 43–150)	Unadjusted RI [95%CI]
Age group
<10 years	1	0	NA*
10–60 years	7	5	3.98 [1.24, 12.8]
>60 years	10	6	4.74 [1.69, 13.3]
Sex
Male	12	8	4.26 [1.72, 10.6]
Female	6	3	5.68 [1.39, 23.3]
Any infection†
Yes	8	5	4.55 [1.46, 14.2]
No	10	6	4.74 [1.69, 13.3]
Gastrointestinal and/or respiratory infection†
Yes	7	4	4.97 [1.42, 17.4]
No	11	7	4.47 [1.70, 11.7]
Gastrointestinal infection†
Yes	4	3	3.78 [0.83, 17.4]
No	14	8	4.97 [2.05, 12.0]
Respiratory infection†
Yes	4	1	11.4 [1.22, 106]
No	14	10	3.98 [1.74, 9.09]
BC level‡
BC level 1	7	4	3.55 [1.38, 9.15]
BC level 2	11	7	7.58 [1.96, 29.3]

BC, Brighton Collaboration; NA, not applicable; RI, relative incidence; SCCS, self-controlled case series.

^*Not evaluable as there were no cases in the control period.

^†Within 3 weeks prior to onset of GBS/FS.

^‡No influenza A(H1N1)-vaccinated case was classified in BC level 3.