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Table 1 Characteristics of Japanese subjects in the primary analysis

From: Influenza vaccination effectiveness for people aged under 65 years in Japan, 2013/2014 season: application of a doubly robust method to a large-scale, real-world dataset

Characteristics by age group

Vaccinee

Non-vaccinee

P Value a

1–64 years

 N

145,784

223,641

 

 Age (median [interquartile range])

14 [7, 39]

22 [10, 43]

< 0.001

 Female

64,914 (44.5%)

98,589 (44.1%)

0.008 *

 Vaccination in the 2012/2013 season

91,541 (62.8%)

20,050 (9.0%)

< 0.001 *

 Insured persons (vs dependents) b

45,859 (31.5%)

79,394 (35.5%)

< 0.001 *

 Number of children aged 0 to 15 years in a family (median [interquartile range]) c

1 [0, 1]

1 [0, 1]

< 0.001

Before influenza season

 Number of outpatient visits

  During office hours (median [range])

2 [0–118]

1 [0–112]

< 0.001

  Outside office hours (median [range])

0 [0–57]

0 [0–61]

< 0.001

 Emergency hospitalization

151 (0.1%)

348 (0.2%)

< 0.001 *

 High-risk condition

34,792 (23.9%)

43,735 (19.6%)

< 0.001 *

During influenza season

 Preceding onset of influenza in family members

27,817 (19.1%)

38,620 (17.3%)

< 0.001 *

1–4 years

 N

23,534

24,101

 

 Age (median [interquartile range])

3 [2, 4]

2 [2, 3]

< 0.001

 Female

11,387 (48.4%)

11,809 (49.0%)

0.184 *

 Vaccination in the 2012/2013 season

14,561 (61.9%)

2620 (10.9%)

< 0.001 *

 Insured persons (vs dependents) b

 Number of children aged 0 to 15 years in a family (median [interquartile range]) c

1 [1, 1]

1 [1, 1]

0.005

Before influenza season

 Number of outpatient visits

  During office hours (median [range])

5 [0–92]

4 [0–65]

< 0.001

  Outside office hours (median [range])

0 [0–19]

0 [0–16]

< 0.001

 Emergency hospitalization

15 (0.1%)

25 (0.1%)

0.155 *

 High-risk condition

7335 (31.2%)

7451 (30.9%)

0.552 *

During influenza season

 Preceding onset of influenza in family members

5095 (21.6%)

5452 (22.6%)

0.011 *

5–12 years

 N

43,535

50,247

 

 Age (median [interquartile range])

8 [6, 10]

9 [7, 11]

< 0.001

 Female

21,215 (48.7%)

24,227 (48.2%)

0.116 *

 Vaccination in the 2012/2013 season

33,310 (76.5%)

6118 (12.2%)

< 0.001 *

 Insured persons (vs dependents) b

 Number of children aged 0 to 15 years in a family (median [interquartile range]) c

1 [1, 2]

1 [1, 2]

< 0.001

Before influenza season

 Number of outpatient visits

  During office hours (median [range])

3 [0–85]

2 [0–73]

< 0.001

  Outside office hours (median [range])

0 [0–22]

0 [0–53]

< 0.001

 Emergency hospitalization

24 (0.1%)

25 (0.05%)

0.776 *

 High-risk condition

10,193 (23.4%)

9589 (19.1%)

< 0.001 *

During influenza season

 Preceding onset of influenza in family members

10,424 (23.9%)

13,024 (25.9%)

< 0.001 *

13–19 years

 N

18,123

31,993

 

 Age (median [interquartile range])

14 [13, 15]

15 [14, 16]

< 0.001

 Female

8811 (48.6%)

15,536 (48.6%)

0.904 *

 Vaccination in the 2012/2013 season

11,162 (61.6%)

4862 (15.2%)

< 0.001 *

 Insured persons (vs dependents) b

158 (0.9%)

327 (1.0%)

0.107 *

 Number of children aged 0 to 15 years in a family (median [interquartile range]) c

1 [0, 1]

1 [0, 1]

< 0.001

Before influenza season

 Number of outpatient visits

  During office hours (median [range])

1 [0–74]

1 [0–61]

< 0.001

  Outside office hours (median [range])

0 [0–20]

0 [0–21]

< 0.001

 Emergency hospitalization

15 (0.1%)

47 (0.1%)

0.066 *

 High-risk condition

2219 (12.2%)

3044 (9.5%)

< 0.001 *

During influenza season

 Preceding onset of influenza in family members

3479 (19.2%)

6094 (19.0%)

0.688 *

20–64 years

 N

60,591

117,019

 

 Age (median [interquartile range])

42 [35, 50]

42 [34, 50]

< 0.001

 Female

23,501 (38.8%)

47,013 (40.2%)

< 0.001 *

 Vaccination in the 2012/2013 season

32,508 (53.7%)

6168 (5.3%)

< 0.001 *

 Insured persons (vs dependents) b

45,701 (75.4%)

78,797 (67.3%)

< 0.001 *

 Number of children aged 0 to 15 years in a family (median [interquartile range]) c

0 [0, 2]

0 [0, 1]

< 0.001

Before influenza season

 Number of outpatient visits

  During office hours (median [range])

1 [0–118]

1 [0–112]

< 0.001

  Outside office hours (median [range])

0 [0–57]

0 [0–76]

< 0.001

 Emergency hospitalization

96 (0.2%)

250 (0.2%)

0.013 *

 High-risk condition

15,044 (24.8%)

23,525 (20.1%)

< 0.001 *

During influenza season

 Preceding onset of influenza in family members

8819 (14.6%)

13,929 (11.9%)

< 0.001 *

  1. Subjects were stratified by age-group and vaccination status in the 2013/2014 influenza season
  2. aThe χ2 test was used for categorical variables (*) and the Mann-Whitney test for continuous variables (†) between vaccinees and non-vaccinees in the 2013/2014 influenza season
  3. bAll children aged under 18 years were treated as dependents
  4. cNumber of other dependents aged 0 to 15 years covered by the same insurance number