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Table 3 Proportion of influenza B infections by age group and healthcare setting (Victoria vs Yamagata lineages)*, Italy 2004/2005–2016/2017

From: Co-circulation of the two influenza B lineages during 13 consecutive influenza surveillance seasons in Italy, 2004–2017

Variables

B/Victoria (N = 1267)

B/Yamagata (N = 1097)

RRcrude

(95% CI)

RRadj

(95% CI)

p-value**

n. (%)

n. (%)

Median age (IQR)

7 (9)

13 (41)

    

< 0.001***

Age group (years)

 0–4

302 (23.8)

190 (17.3)

1.91

(1.53–2.39)

2.13

(1.70–2.67)

< 0.001

 5–14

655 (51.7)

380 (34.7)

1.97

(1.59–2.45)

2.27

(1.82–2.84)

< 0.001

 15–44

198 (15.7)

214 (19.5)

1.50

(1.19–1.90)

1.67

(1.31–2.12)

< 0.001

 45–64

54 (4.2)

190 (17.3)

0.69

(0.50–0.95)

0.72

(0.52–0.99)

0.047

  > 64

58 (4.6)

123 (11.2)

Ref

–

Ref

–

–

Healthcare settings

 Community

927 (76.6)

810 (77.8)

Ref

–

Ref

–

–

 Hospitals

283 (23.4)

231 (22.2)

1.03

(0.94–1.13)

1.24

(1.15–1.35)

< 0.001

  1. *Crude and adjusted (adj) relative risk (RR) estimated using the univariable and multivariable log-binomial regression model with age bracket of > 64 as a reference class;
  2. CI: confidence interval
  3. **p-value of the multivariable binomial negative model;
  4. ***p-value of the U Mann-Whitney test; p-values of < 0.05 were considered statistically significant
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BMC Infectious Diseases

ISSN: 1471-2334

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