Live vaccines and test results
A question that has come up is regarding the recent use of live vaccines and the impact on test results and interpretation.
A field study conducted by Dr. David Kelton of the Ontario Vet College, as well as studies done by Dr. Rob Tremblay of Boehringer Ingelheim, show that when cows that had been previously vaccinated, or were otherwise seropositive, showed no sign of either viremia or BVD virus in milk and consistently returned test negative results after cows had been boosted with a modified-live viral vaccine. Therefore it is unlikely to have false positive test results on the herd screening (PCR) or individual animals (antigen ELISA), due to the recent use of live vaccine.
Also, as is usually recommended with all BVD testing, positive cow results will be accompanied with a recommendation to retest in 14-21 days using the same or an alternative method.