Table 1. Effects of shedder vaccination status on contact bird disease symptoms, mortality and FVL for a model also including contact bird sex and shedder DPI, but excluding DPI by vaccination status interaction.
Full results, including models with the interaction, are in S1 Table.
| Contact bird response | Shedder vaccination coefficient (SE)6 | Test statistic7 | p-value |
|---|---|---|---|
| Disease status1 | 8.19 (1.50) | 5.45 | <0.0001 *** |
| Mortality2 | 1.74 (0.20) | 8.76 | <0.0001 *** |
| N tissues with tumours3 | 0.50 (0.13) | 3.71 | <0.0005 *** |
| Vagus nerve enlargement4 | 0.22 (0.23) | 0.94 | 0.35 |
| Brachial nerve enlargement4 | 1.30 (0.26) | 5.01 | <0.0001 *** |
| Sciatic nerve enlargement4 | 1.30 (0.24) | 5.36 | <0.0001 *** |
| FVL5 | 1.98 (0.11) | 18.3 | <0.0001 *** |
1Infected contacts (qPCR) only. Logistic regression. Coefficient = mean log odds ratio for presence of contact disease symptoms when exposed to sham-vaccinated relative to vaccinated shedders.
2Infected contacts (qPCR) only. Cox proportional hazards. Coefficient = log hazard ratio of contact death at a given time point associated with sham-vaccinated relative to vaccinated shedders.
3Diseased contacts (necropsy) only. Poisson GLM. Coefficient = mean difference in number of contact tissues containing tumours with sham-vaccination.
4Diseased contacts (necropsy) only. Ordinal logistic regression. Coefficient = proportional log odds of an increase in contact nerve enlargement ranking with sham-vaccination.
5All contacts. Least square mean difference in contact bird log10(viral load + 1 × 10−5) with sham-vaccinated relative to vaccinated shedders.
6Positive = increase in contacts when exposed to sham-vaccinated relative to vaccinated shedders, except for FVL (>1 = increase with sham-vaccination).
7t statistic for linear regression, z statistic for all other models.
Abbreviations: DPI, days post-infection; FVL, feather viral load; GLM, generalized linear model; qPCR, quantitative polymerase chain reaction; SE, standard error.