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Table 1 Descriptive statistics of the measurements and frequency tables in the study of influenza A virus circulation

From: Assessment of exposure to influenza A viruses in pigs between weaning and market age

Variable

Study 1

Study 2

Median (IQR)

N positive± (%)

Median (IQR)

N positive (%)

H3N2_A*

 1\\

10 (15)

15 (18.5)

40 (40)

66 (88.0)

 2

10 (10)

8 (10.8)

 3

80 (120)

77 (97.4)

5 (0)

0 (0)

 4 (pigs in study)

40 (60)

35 (61.4)

80 (0)

37 (97.3)

 4\

80 (0)

78 (98.7)

H3N2_B*

 1

40 (60)

49 (60.4)

160 (80)

72 (96.0)

 2

40 (20)

51 (68.9)

 3

80 (120)

70 (88.6)

20 (10)

16 (21.9)

 4 (pigs in study)

80 (40)

52 (91.2)

10 (10)

8 (21.0)

 4

20 (70)

38 (48.1)

H3N2_C*

 1

20 (30)

39 (48.1)

80 (120)

61 (81.3)

 2

20 (30)

20 (27.0)

 3

80 (1270)

42 (54.4)

10 (5)

5 (6.8)

 4 (pigs in study)

10 (5)

1 (1.7)

10 (5)

2 (2.5)

 4

10 (5)

2 (5.2)

H3N2_H

 1

40 (140)

60 (74.0)

80 (120)

67 (89.3)

 2

20 (30)

19 (25.6)

 3

80 (120)

63 (79.7)

10 (5)

3 (4.1)

 4 (pigs in study)

20 (10)

12 (21.0)

5 (0)

1 (2.6)

 4

5 (5)

3 (3.8)

H1N2

 1

40 (20)

43 (53.0)

80 (120)

62 (82.6)

 2

20 (30)

22 (29.7)

 3

10 (5)

0 (0)

5 (5)

4 (5.4)

 4 (pigs in study)

10 (5)

1 (1.7)

10 (0)

1 (2.6)

 4

10 (0)

3 (3.8)

H1N1_C§

 1

10 (15)

7 (8.6)

10 (15)

14 (18.6)

 2

5 (0)

0 (0)

 3

5 (0)

3 (3.8)

5 (0)

2 (2.7)

 4 (pigs in study)

5 (0)

0 (0)

5 (5)

1 (2.6)

 4

5 (5)

1 (1.2)

H1N1_P

 1

10 (15)

15 (18.5)

20 (30)

24 (32.0)

 2

20 (10)

15 (20.2)

 3

10 (5)

1 (1.2)

20 (30)

33 (45.2)

 4 (pigs in study)

10 (10)

0 (0)

40 (40)

35 (92.1)

 4

40 (40)

66 (83.5)

H1N1_H

 1

40 (70)

42 (51.8)

20 (30)

22 (29.3)

 2

5 (5)

4 (5.4)

 3

20 (20)

39 (49.3)

80 (140)

54 (73.9)

 4 (pigs in study)

5 (5)

0 (0)

20 (30)

15 (39.4)

 4

40 (60)

45 (56.9)

  1. The two longitudinal studies were performed in nursery pigs, between November 18th, 2013 and January 9th and between April 4th, 2014 and May 29th, 2014, respectively. Fourth measurement was taken at the end of finisher period. Median and interquartile range were used. Any titer < 1:10 was treated, for the purpose of analysis, as 5.
  2. *Different H3N2 variants broadly classified into cluster 4 of H3N2 swine influenza A virus and isolated in Ontario in 2012 and used in the hemagglutination inhibition assay.
  3. H3N2 and H1N1 viruses detected in the study and used as antigens in the hemagglutination inhibition assay.
  4. H1N2 with hemagglutinin of the 2009 pandemic lineage and neuraminidase of the Cluster 4 H3N2 IAV-S.
  5. §H1N1 IAV-S broadly classified as the classical swine H1N1 virus used in hemagglutinin inhibition assay.
  6. H1N1 IAV-S of the 2009 H1N1 pandemic lineage used in the hemagglutination inhibition assay.
  7. \\Number of blood sampling performed: (1) entry to nursery, (2) mid-nursery, (3) end of nursery, (4) end of finisher.
  8. \Sum of pigs in the longitudinal study and pigs selected randomly in the finisher barn.
  9. ±Number of pigs that had a positive titer (≥ 1:40) in each of the measurements.