Table 1 Demographic and baseline clinical characteristics of patients in the four groups

Characteristics

Median (interquartile) age (years)

41 (28–57)

49 (27–62)

47 (32–51)

18 (17–34)

0.880

0.331

0.715

0

Age groups (years)

0.25

1.0

0.443

0

 ≤ 18

11 (11%)

2 (4%)

1 (9%)

235 (61%)

··

··

··

··

 19–40

40 (39%)

22 (42%)

2 (18%)

72 (19%)

··

··

··

··

 41–65

39 (38%)

18 (35%)

8 (73%)

58 (15%)

··

··

··

··

 ≥ 66

13 (13%)

10 (19%)

0

19 (5%)

··

··

··

··

Male sex

45 (44%)

37 (71%)

8 (73%)

162 (42%)

0.0012

0.066

0.0495

0.784

Familial cluster

28 (27%)

8 (15%)

0

166 (46%)

0.10

0.10

0.371

0.001

Coexisting conditions

34 (33%)

17 (33%)

6 (55%)

39 (10.2%)

0.935

0.246

0.306

< 0.0001

 Diabetes

14 (14%)

10 (19%)

5 (45%)

10 (3%)

0.36

0.0029

0.039

0

 Hypertension

12 (12%)

3 (6%)

1 (9%)

23 (6%)

0.38

1.0

0.546

0.048

 Cardiovascular disease

8 (8%)

3 (6%)

0

6 (1.6%)

0.90

1.0

1.0

0.003

 Chronic obstructive pulmonary disease

0

1 (2%)

0

0

0.34

··

1.0

··

Number of vaccination doses

< 0.0001

0.001

0.078

< 0.0001

 0

40 (39%)

34 (65%)

11 (100%)

2 (1%)

··

··

··

··

 1

7 (7%)

16 (31%)

0

11 (3%)

··

··

··

··

 2

53 (51%)

2 (4%)

0

346 (90%)

··

··

··

··

 3

1 (1%)

0

0

21 (5%)

··

··

··

··

Fever

36 (35%)

11 (21%)

3 (27%)

96 (25%)

0.21

0.86

1.0

0.038

Highest temperature, °C

0.13

0.86

1.0

0.083

 < 37.3

67 (65%)

41 (79%)

8 (73%)

283 (74%)

··

··

··

··

 37.3–38

17 (17%)

5 (10%)

1 (9%)

48 (12%)

··

··

··

··

 > 38

19 (18%)

6 (11%)

2 (18%)

53 (14%)

··

··

··

··

Cough

26 (25%)

14 (27%)

3 (27%)

240 (63%)

0.82

1.0

1.0

0

Expectoration

16 (16%)

5 (10%)

1 (9%)

112 (29%)

0.31

0.90

1.0

0.005

Myalgia or fatigue

9 (9%)

19 (36%)

4 (36%)

30 (6%)

0.0005

0.098

1.0

0.002

Nasal congestion

7 (7%)

9 (17%)

0

96 (25%)

0.042

1.0

0.31

0

Loss of smell and taste

2 (2%)

5 (10%)

2 (18%)

4 (1%)

0.078

0.046

0.769

0.816

Headache

3 (3%)

3 (6%)

0

7 (2%)

0.67

1.0

1.0

0.763

Dyspnea

0

0

0

3 (0.8%)

··

··

··

1

Severity score

0.706

0.519

0.788

< 0.0001

 4

84 (81%)

40 (77%)

8 (73%)

380 (99%)

··

··

··

··

 5

17 (17%)

10 (19%)

3 (27%)

4 (1%)

··

··

··

··

 9

2 (2%)

2 (4%)

0

··

··

··

··

The incubation period (days)

3 (2–7) (n = 81)

2 (1–3) (n = 48)

4 (2–6) (n = 8)

2 (1–2) (n = 97)

0.31

0.0004

0.815

0

Time from illness onset to first hospital admission (days)

2.5 (0–5.0)

5 (4–5)

3 (2–4)

2 (1–3) (n = 362)

0.003

< 0.0001

0.999

0.840