Lack of evidence for claims of farmers in south-eastern Germany regarding adverse reactions ascribed to BTV-8 vaccines

Farmers in south-eastern Germany who claimed adverse reactions due to the application of BTV-8 vaccines during the compulsory vaccination programme in 2008/2009 were invited to participate in an epidemiological study to prove whether there was evidence for a plausible relationship between the immunizations and the reported symptoms. Ten farms were available for on-site visits; all other farmers (N = 120) who had registered to participate in the study were asked to complete a questionnaire and to provide evidence for the claimed adverse reactions. 25 questionnaires were returned. Although a wide range of symptoms were reported, in most cases the documentation of clinical signs, pathological alterations and fatalities was not sufficient to conclude on a causal relationship. Similarly, most of the suspected adverse events evaluated as pharmacovigilance reports had to be categorized as "unclassified due to insufficient information".