Model confirms mixed badger culling and vaccination reduces bovine TB

Bovine tuberculosis (TB) is a costly disease shared by cattle and badgers (Meles meles) in Britain and Ireland, and reducing infection in cattle has long required some form of badger management. Faced with this problem, researchers compared a real-world field trial with predictions from an existing simulation model. The field trial used a selective approach: badgers that tested positive were culled, while those that tested negative were vaccinated, a strategy known as TVR. The original simulation model had been used to predict the likely effects of such a trial in Northern Ireland. Graham Smith and colleagues set out to see how well that model matched reality. By directly comparing field results from the TVR study with the model’s forecasts, the team aimed to test whether the model could be trusted to guide policy choices about TB control. This work addresses a practical management question: can a model built before a trial reliably forecast what happens when selective culling and vaccination are combined in the field?

The comparison focused on how the model handled a key behavioral uncertainty: social perturbation, the idea that culling disrupts badger social structure in ways that might change disease spread. Initial model runs showed results depended strongly on whether such perturbation occurred after culling. The actual field study, however, showed no evidence of social perturbation in the badger population following the TVR intervention. In response, the researchers re-ran the simulation with the initial conditions matching the TVR study and explicitly assumed no social perturbation. Under those conditions the model predicted outcomes similar to those observed in the field: comparable numbers of badgers caught, similar numbers testing positive, and a substantial decline in TB prevalence. These parallel results between model and field data serve to validate the model’s assumptions and its ability to reproduce key trial outcomes under the no-perturbation scenario.

Validating the simulation model matters because it demonstrates the utility of predictive modelling for this disease system and for planning interventions. With a model that reproduces field outcomes, managers can better anticipate the consequences of different strategies and weigh trade-offs before acting. The study’s findings are particularly timely as the UK government shifts away from widespread badger culling in England toward greater use of vaccination. The combined approach used in the TVR trial — culling test-positive animals and vaccinating test-negative ones — appears from both field data and the validated model to be a more robust method of disease management than vaccination alone. In short, the match between model and trial gives policymakers a firmer evidence base when choosing how to control bovine TB at the cattle–badger interface.