Table 2 IAV antibody presence, antibody level (S/N), viral presence and viral load (Ct) per stable unit for herd IAV vaccination regime, and p values from linear models (Antibody S/N, Virus Ct) and generalized linear models (antibody and virus positive) including herds as explanatory variable

Herds, n

10

5

5

Samples, n

200

100

100

Mating unit

Virus positive, n (%)

4 (2%)

0 (0%)

4 (4%)

Virus Ct., mean*

33.8

–

33.8

Gestation unit

Antibody positive, n (%)

161 (81%)

69 (69%)

92 (92%)

Antibody S/N, mean*

0.26

0.31

0.21

Farrowing unit sows

Antibody positive, n (%)

153 (77%)

58 (58%)

95 (95%)

Antibody S/N, mean*

0.25

0.33

0.20

Virus positive, n (%)

4 (2%)

0 (0%)

4 (4%)

Virus Ct., mean*

33.8

–

33.8

Farrowing unit piglets

Virus positive, n (%)

24 (12%)

12 (12%)

12 (12%)

Virus Ct., mean*

27.8

26.0

29.5