Table 7.
Mixed effects linear regression of haemagglutination inhibition titre with ≥40 (threshold) for immunogen H1N1pdm09 in individual pigs
| HAIT titre (IU/ml) in individual pig for immunogen H1N1pdm09 | |||||
|---|---|---|---|---|---|
| Predictors | Coefficients | SE | P values | 95% CI | |
| Year | |||||
| 2009 | Reference | ||||
| 2010 | −218.58 | 145.79 | 0.134 | −504.33 | 67.16 |
| 2011 | 148.50 | 142.12 | 0.296 | −130.05 | 427.06 |
| 2012 | 262.59 | 141.63 | 0.064 | −14.99 | 540.18 |
| 2013 | −37.03 | 141.79 | 0.794 | −314.94 | 240.87 |
| 2014 | −74.02 | 142.61 | 0.604 | −353.53 | 205.48 |
| 2015 | −102.30 | 143.03 | 0.474 | −382.63 | 178.03 |
| 2016 | −49.26 | 143.26 | 0.731 | −330.04 | 231.53 |
| 2017 | 40.84 | 147.15 | 0.781 | −247.56 | 329.24 |
| Production | |||||
| Fattening | Reference | ||||
| Sow | 128.81 | 57.59 | 0.025 | 15.93 | 241.69 |
| Heterologous reactions | |||||
| 1 antigen subtype | Reference | ||||
| 2 antigen subtypes | 410.97 | 23.12 | <0.001 | 365.65 | 456.29 |
| 3 antigen subtypes | 1302.97 | 53.09 | <0.001 | 1198.93 | 1407.02 |
| 4 antigen subtypes | 74.66 | 657.03 | 0.91 | −1213.09 | 1362.41 |
| Proportion positive | 574.54 | 142.96 | <0.001 | 294.35 | 854.73 |
| Constant | −449.92 | 199.23 | 0.024 | −840.41 | −59.43 |
Sampling of 8,200 pigs' sera came from 3,626 positive herd tests. Norwegian serosurveillance data between 2009 and 2017.
Categorical predictors: Production. Ordinal predictors: Year & Heterologous reactions (number of antigens). Continuous predictors: Proportion pigs positive.