As someone whose family keeps cows:
DEFRA are less concerned with eradicating TB in cattle than protecting beef exports. There has been a vaccine for bovine TB for years. But it is not compatible with the skin test which is a prerequisite for exporting beef to most countries (the current test doesn't work on vaccinated cattle). They are in the process of developing a new test, which is taking years and will then need to be incorporated into international trading standards, which isn't going to be quick either.
All of which is just masking the root cause of TB's prevalence anyway, which is effectively 'battery' farming cows. Who would have thought that cramming a maximum number of animals into a minimum sized space would result in an airborne disease spreading through them? These places are basically like Victorian workhouses or WW1 trenches, which were notorious for being hotbeds of tuberculosis in humans.
If you're a farmer though, that's how you need to keep animals if you want to be competitive in the market. Unless you're lucky enough to have inherited a large amount of land and decide to use it to prioritise the health of your animals over maximising profits.
Maybe a techno-fix will sustain this for a while but ultimately it's too meshed in with the inertia of capitalist economics and demand for low cost animal products for the problem to be properly solved.
Shooting badgers has been used to kick the can down the road and avoid sincerely tackling the problem of bovine TB, while also throwing a toy to those in the rural community and humouring them by allowing them to hunt something. A shrewd move for a career politician but does nothing to look out for animals, farmers, vets, the public, the environment or the economy.