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Table 4 IVE by age and strain overall and for admissions targeted for influenza vaccination

From: Influenza epidemiology and influenza vaccine effectiveness during the 2015–2016 season: results from the Global Influenza Hospital Surveillance Network

Population Strain Age Influenza-positive Influenza-negative Crude IVE Adjusted IVEa
Total Vaccinated Total Vaccinated Percent (95% CI) P interaction Percent (95% CI) P interaction
Overall Any Any 2269 246 6702 1250 47.0 (38.6, 54.2)   16.3 (0.4, 29.7)  
  <  65 y 1897 100 4814 354 29.9 (11.9, 44.2) 0.90 11.9 (−12.9, 31.3) 0.70
  ≥ 65 y 372 146 1888 896 28.5 (10.2, 43.0)   13.4 (−12.7, 33.5)  
A(H1N1)pdm09 Any 1327 110 6702 1250 60.6 (51.6, 67.9)   36.0 (18.0, 50.1)  
  <  65 y 1153 37 4814 354 58.2 (41.0, 70.4) 0.0054 44.8 (19.2, 62.3) 0.69
  ≥ 65 y 174 73 1888 896 20.0 (−9.6, 41.6)   5.7 (−36.4, 34.8)  
A(H3N2) Any 224 22 6702 1250 52.5 (25.9, 69.6)   16.1 (− 35.9, 48.2)  
  <  65 y 148 6 4814 354 46.8 (−21.4, 76.7) 0.26 40.2 (−39.5, 74.4) 0.44
  ≥ 65 y 76 16 1888 896 70.5 (48.2, 83.2)   6.8 (−73.3, 49.9)  
A not subtyped Any 153 16 6702 1250 49.1 (14.2, 69.8)   49.5 (5.5, 73.0)  
  <  65 y 128 8 4814 354 16.0 (− 73.2, 59.3) 0.40 −3.7 (− 127.9, 52.8) 0.12
  ≥ 65 y 25 8 1888 896 47.9 (−21.4, 77.6)   67.6 (19.4, 87.0)  
B/Yamagata Any 41 6 6702 1250 25.2 (−78.2, 68.6)   −96.9 (− 406.0, 23.4)  
  <  65 y 33 4 4814 354 −73.8 (− 397.2, 39.3) 0.11 0.59
  ≥ 65 y 8 2 1888 896 63.1 (−83.5, 92.6)   
B/Victoria Any 511 83 6702 1250 15.4 (−7.9, 33.7)   −49.3 (−99.5, −11.7)  
  <  65 y 426 39 4814 354 −27.0 (−79.6, 10.2) 0.82 −32.9 (−94.0, 9.0) 0.29
  ≥ 65 y 85 44 1888 896 −18.8 (−83.6, 23.1)   −1.8 (−67.2, 38.0)  
B not subtyped Any 29 11 6702 1250 − 166.5 (− 466.0, −25.5)   −322.2 (− 948.5, −70.0)  
  <  65 y 22 7 4814 354 − 488.0 (− 1354.1, − 137.7) 0.14 0.65
  ≥ 65 y 7 4 1888 896 −47.6 (− 561.7, 67.1)   
Individuals targeted for influenza vaccination Any Any 1106 189 3554 1065 51.8 (42.7, 59.5)   16.2 (−3.6, 32.2)  
  <  65 y 734 43 1666 169 44.9 (22.0, 61.1) 0.21 5.3 (−39.4, 35.6) 0.30
  ≥ 65 y 372 146 1888 896 28.5 (10.2, 43.0)   13.4 (−12.7, 33.5)  
A(H1N1)pdm09 Any 646 93 3554 1065 60.7 (50.4, 68.9)   23.0 (−3.3, 42.6)  
  <  65 y 472 20 1666 169 60.8 (36.8, 75.7) 0.011 20.9 (−36.0, 54.0) 0.54
  ≥ 65 y 174 73 1888 896 20.0 (−9.6, 41.6)   5.7 (−36.4, 34.8)  
A(H3N2) Any 137 19 3554 1065 62.4 (38.5, 77.0)   −9.1 (−88.4, 36.8)  
  <  65 y 61 3 1666 169 54.2 (−48.0, 85.8) 0.52 −2.5 (− 263.0, 71.1) 0.10
  ≥ 65 y 76 16 1888 896 70.5 (48.2, 83.2)   6.8 (−73.3, 49.9)  
A not subtyped Any 71 12 3554 1065 52.5 (11.2, 74.6)   61.7 (21.6, 81.3)  
  <  65 y 46 4 1666 169 15.6 (−138.2, 70.1) 0.49 25.7 (− 129.6, 76.0) 0.50
  ≥ 65 y 25 8 1888 896 47.9 (−21.4, 77.6)   67.6 (19.4, 87.0)  
B/Yamagata Any 26 5 3554 1065 44.4 (−48.0, 79.1)   −104.3 (− 508.0, 31.4)  
  <  65 y 18 3 1666 169 −77.2 (− 518.6, 49.3) 0.13 − 115.4 (− 747.1, 45.2) 0.94
  ≥ 65 y 8 2 1888 896 63.1 (−83.5, 92.6)   
B/Victoria Any 215 55 3554 1065 19.7 (−10.1, 41.4)   −25.6 (−86.3, 15.4)  
  <  65 y 130 11 1666 169 18.1 (−55.0, 56.7) 0.33 −17.3 (−144.8, 43.8) 0.71
  ≥ 65 y 85 44 1888 896 −18.8 (− 83.6, 23.1)   −1.8 (−67.2, 38.0)  
B not subtyped Any 17 7 3554 1065 −63.6 (−331.1, 37.9)   
  <  65 y 10 3 1666 169 − 279.6 (− 1385.0, 3.0) 0.37
  ≥ 65 y 7 4 1888 896 −47.6 (−561.7, 67.1)   
  1. Abbreviations: CI 95% CI, IVE influenza vaccine effectiveness
  2. aAdjust for age, sex, number of chronic conditions, time from onset of symptoms to swab, epidemiological week at admission, and site