Assessment of the safety of Bacillus Calmette-Guérin vaccine administered orally to badgers (Meles meles).

•Vaccinating badgers against TB is a tool under consideration to reduce the prevalence of bovine TB.•Showing an oral vaccine is safe for badgers and the environment is mandatory for licensing.•A high dose of BCG given orally to badgers was safe with occasional excretion of BCG in the faeces.•BCG was not cultured from tissues and did not transmit to unvaccinated badgers.•The risk of sensitising cattle due to BCG excreted from badgers is expected to prove extremely low.