The reason badgers have been culled in the UK is because they can harbour tuberculosis, which they then pass on to cattle… which, being in the human food chain or providing dairy products to it, have to be culled if they’re found to have TB infections. At which point you sort of wonder, well, why can’t we just vaccinate cattle like we do ourselves? And the answer is that we can… but we can’t then tell the difference between a vaccinated animal and one which actually has the disease — and the vaccine is only about 70% effective in cattle.
Clearly, it would be better if we could vaccinate cattle, so a mixed group of scientists from the UK and India have come up with a solution. The vaccine is pretty effective, and we can’t ever hope for 100% accuracy (due to variation between individuals and other random chance events), so we can’t improve that and prevent the need to test at all. So somehow, they figured, we’ve got to make the tests work.
So they went ahead and tried (so far only in guinea pigs, as a proof of concept) creating a new vaccine which omits certain surface proteins from the usual vaccine. These surface proteins are used in the test for active tuberculosis infection — so in theory, with them deleted, a vaccinated cow would no longer give a false positive. Cows vaccinated with this alternative vaccine would only test positive if they were actually infected with the real tuberculosis bacterium, allowing just those cows to be culled.
It’s especially good-sounding since some studies have suggested that culling badgers prompts living badgers to increase their range… increasing their transmission of tuberculosis to cattle. It would be much better if we could just make cows largely immune to TB, and leave badgers alone.
It’s still being tested and certainly isn’t going to save any badgers this year or next, and I imagine it will also need to be tested for both efficacy and safety in cows (does it still protect 70% of the herd, or is it less due to the omitted surface proteins? does it impact the health of the cattle in any negative ways? and probably, yes, does it make any difference to humans who consume the meat or dairy products?) but it’s a clever way of thinking round the problem, and a hopeful step.