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Table 1 Characteristics of cases of pandemic influenza reported in the initiation period (week 18 to week 41, 2009) and acceleration period (week 42 to week 46, 2009)

From: The first wave of pandemic influenza (H1N1) 2009 in Germany: From initiation to acceleration

 

Number of cases with information

Initiation period (%)a

Acceleration period (%)a

Total

53,968

23,789 (44.1)

30,179 (55.9)

Age groups

53,930

23,783

30,147

   Median [quartiles]

 

19 [16,26]#

15 [10,26]#

   0-4 years

2,076

516 (2.2)

1,560 (5.2)

   5-14 years

16,989

3,794 (16.0)

13,195 (43.8)

   15-24 years

20,295

12,854 (54.0)

7,441 (24.7)

   25-59 years

13,975

6,398 (26.9)

7,577 (25.1)

   ≥ 60 years

595

221 (0.9)

374 (1.2)

Origin of infection

53,757

23,714

30,043

   Autochthonous cases

37,573

9,235 (38.9)

28,338 (94.3)

Risk factors

39,748

17,579

22,169

   All cases

 

820 (4.7)*

1,539 (6.9)*

Autochthonous cases

27,486

411/6,868 (6.0)**

1,458/20,618 (7.1)**

Imported cases

12,140

405/10,644 (3.8)**

77/1,476 (5.2)**

   Risk factors

   

Chronic diseases

   

Respiratory disease

1,080

372 (2.1)

708 (3.2)

Cardio-vascular disease

264

107 (0.6)

157 (0.7)

Diabetes

173

63 (0.4)

110 (0.5)

Obesity§

159

71 (0.4)

88 (0.4)

Immunosuppression

112

40 (0.2)

72 (0.3)

Other chronic diseases

458

127 (0.7)

331 (1.5)

Pregnancy

113

40 (0.2)

73 (0.3)

Age groups

39,748

17,533

22,043

0-4 years

1,474

17/367 (4.6)

53/1.107 (4.8)

5-14 years

12,351

101/2,831 (3.6)

571/9,520 (6.0)

15-24 years

15,107

314/9,510 (3.3)

291/5,597 (5.2)

25-59 years

10,368

350/4,711 (7.4)

560/5,657 (9.9)

≥ 60 years

429

38/157 (24.2)

63/272 (23.2)

Symptoms

53,968

23,789

30,179

   ILI

 

2,318 (9.7)

2,924 (9.7)

Diagnosis

   

   Time interval between onset of symptoms and diagnosis

7.253

3 days [2, 5]#

2 days [1,4]#

Antiviral treatment initiated

35,160

15,941

19,219

   All cases

 

4,671 (29.3)

4.491 (24.7)

Cases with underlying chronic disease

2,092

319/743 (42.9)

598/1,278 (46.8)

Cases without risk factors

33,139

4,352/15,198 (28.6)

3,893/17,941 (21.7)

Pregnancy

88

6/34 (17.6)

13/54 (24.1)

   Time interval between symptom onset and start of therapy

 

2 days [1,3]#

1 day [1,2]#

Pneumonia

40,729

18,090

22,639

   All cases with pneumonia

275

93 (0.5)

182 (0.8)

Antiviral treatment initiated

219

33/77 (42.9)

56/142 (39.4)

   Cases with underlying chronic disease

76

19/764 (2.5)

57/1,410 (4.0)

   Cases without risk factors

176

66/16,303 (0.4)

110/20,192 (0.5)

   Pregnancy

99

1/37 (2.7)

1/62(1.6)

Hospitalisation

52,485

23,665

28,820

   All cases hospitalised

2,084

1,117 (4.7)*

967 (3.4)*

Age (years)

 

19 [16,26]#

15 [11,26]#

   Cases with risk factors

2,342

102/814 (12.5)

182/1,528 (11.9)

Age (years)

 

23 [16,41] #

17 [11, 39] #

   Cases without risk factors

37,187

618/16,711 (3.7)*

597/20.476 (2.9)*

Age (years)

 

19 [16,25]#

15 [10,25]#

  1. # Lower/upper quartile
  2. § Obesity requiring treatment or body mass index > 30
  3. a The percentages in brackets refer to the number of cases with available information regarding the variable. In each cell the number printed in bold is used as denominators in a cell. If another denominator is used, it is given in the table.
  4. * Comparison initiation versus acceleration period: p < 0.001
  5. ** Comparison initiation versus acceleration period: p < 0.01