Table 4 Correlates of clinical severity among participants with influenza A, influenza B, and respiratory syncytial virus infection in Macha Zambia

Age, years

 Per year increase

1.00 (0.98–1.01)

–

1.00 (0.91–1.09)

–

0.98 (0.93–1.04)

–

 0–5 months

3 (43%)

Ref

–

0 (0%)

Ref^a

–

8 (80%)

Ref

–

 6–11 months

2 (33%)

0.78 (0.19–3.21)

–

0 (0%)

–

9 (82%)

1.02 (0.67–1.55)

–

 1–4

17 (49%)

1.13 (0.45–2.85)

–

2 (17%)

–

15 (68%)

0.85 (0.56–1.30)

–

 5–15

4 (29%)

0.67 (0.20–2.19)

–

2 (17%)

1.42 (0.23–8.70)

–

0 (0%)

N/A

–

 16–50

2 (22%)

0.52 (0.12–2.30)

–

1 (25%)

2.12 (0.25–18.05)

–

0 (0%)

N/A

–

 51+ 

4 (50%)

1.17 (0.39–3.51)

–

0

N/A

–

1 (100%)

N/A

–

Gender

 Male

19 (46%)

Ref

Ref

0 (0%)

Ref

Ref

17 (63%)

Ref

Ref

 Female

13 (34%)

0.74 (0.43–1.28)

0.67 (0.39–1.16)

5 (23%)

N/A

N/A

16 (70%)

1.10 (0.74–1.64)

1.00 (0.72–1.40)

Current smoker or smoker in the household (n,%)

 No

27 (43%)

Ref

Ref

3 (10%)

Ref

Ref

28 (70%)

Ref

Ref

 Yes

5 (31%)

0.73 (0.33–1.59)

0.72 (0.33–1.58)

2 (100%)

N/A

N/A

5 (50%)

0.71 (0.37–1.37)

0.96 (0.60–1.55)

Underweight (n,%)

 No

21 (32%)

Ref

Ref

5 (17%)

Ref

Ref

29 (63%)

Ref

Ref

 Yes

10 (77%)

2.38 (1.50–3.78)

2.49 (1.57–3.93)

0 (0%)

N/A

N/A

3 (100%)

N/A

N/A

HIV-infected (n,%)

 No

30 (39%)

Ref

Ref

5 (15%)

Ref

Ref

33 (66%)

Ref

Ref

 Yes

2 (67%)

1.69 (0.72–3.94)

1.82 (0.55–6.05)

0 (0%)

N/A

N/A

0 (0%)

N/A

N/A

History of tuberculosis (n,%)

 No

31 (40%)

Ref

Ref

5 (15%)

Ref

Ref

33 (66%)

Ref

Ref

 Yes

1 (100%)

N/A

N/A

0 (0%)

N/A

N/A

0 (0%)

N/A

N/A

Anemia (n,%)

 No

31 (40%)

Ref

Ref

5 (15%)

Ref

Ref

31 (65%)

Ref

Ref

 Yes

1 (50%)

1.24 (0.30–5.10)

1.00 (0.20–4.95)

0 (0%)

N/A

N/A

2 (100%)

N/A

N/A

Objective fever (n,%)

 No

22 (39%)

Ref

Ref

3 (15%)

Ref

Ref

28 (65%)

Ref

Ref

 Yes

10 (43%)

1.11 (0.63–1.95)

1.14 (0.66–1.98)

2 (15%)

1.03 (0.20–5.33)

0.95 (0.17–5.30)

5 (71%)

1.10 (0.65–1.84)

1.18 (0.79–1.76)

Diarrhea (n,%)

 No

28 (44%)

Ref

Ref

2 (8%)

Ref

Ref

29 (67%)

Ref

Ref

 Yes

4 (27%)

0.60 (0.25–1.45)

0.54 (0.22–1.31)

3 (38%)

4.69 (0.94–23.27)

4.65 (0.88–24.42)

4 (57%)

0.85 (0.43–1.66)

0.69 (0.34–1.40)

Duration of ILI symptoms at presentation, days

 Per day increase

1.05 (0.89–1.23)

1.05 (0.91–1.22)

0.81 (0.48–1.39)

0.76 (0.42–1.36)

1.06 (0.93–1.21)

1.07 (0.93–1.23)

 1–2

5 (38%)

Ref

Ref

2 (25%)

Ref

Ref

4 (50%)

Ref

Ref

 3–5

24 (42%)

1.09 (0.52–2.32)

1.27 (0.60–2.71)

3 (15%)

0.60 (0.12–2.94)

0.41 (0.07–2.52)

23 (68%)

1.35 (0.65–2.81)

1.31 (0.68–2.54)

 6+ 

3 (33%)

0.87 (0.27–2.74)

0.44 (0.06–3.21)

0 (0%)

N/A

N/A

6 (75%)

1.50 (0.67–3.34)

1.64 (0.77–3.48)