Skip to main content

Table 2 Results of the univariate analysis for the vaccine exposure variables levels (IRR = incidence rate ratio)

From: A relevant long-term impact of the circulation of a potentially contaminated vaccine on the distribution of scrapie in Italy. Results from a retrospective cohort study

  Exposure level Total no. of flocks No. of positive flocks Incidence IRR
    (new cases per 1000 farms) (95%CI)
Categorization of the number of vets or retailers who had bought the vaccine 1 (0-1vet or retailer) 71 216 47 0.66 Referent
2 (>1 vet or retailer) 7247 10 1.4 2.1 (1.1-4.1)
Categorization of the number of farms that had bought the vaccine 1 (0–4 farms) 49 849 25 0.50 (*) Referent
  2 (5–10 farms) 20 821 17 0.82 (*) 1.6 (0.88-3.0)
  3 (>10 farms) 7793 15 1.9 (*) 3.8 (2.0-7.3)
Herd size (median for each province)   78 463 57   1.005
      (1.001-1.01)
  1. Both exposure variables related to the vaccine [(1) categorization of the number of veterinarians or retailers who had purchased the vaccine and (2) categorization of the number of farms that had bought the vaccine] show a significant association with disease levels. The categorization of the number of farms that had bought the vaccine shows a statistically significant upward trend in risk. The median farm size for each province resulted as not having a health impact on the disease risk.
  2. (*) Test for trend: χ2 = 2.92, P value = 0.003.