Firstly, we are grateful for sight of two letters on vaccination using BCG, from Dr. Lewis Thomas, whose job description included the licensing of pharmaceutical drugs. Firstly a letter published in the veterinary press late last year, commenting on the vaccination of badgers:
There are a number of remarkable features concerning the proposed joint project that you report recently between the Badger Trust and the NFU (19.12.11) not least the apparent realisation by the Badger Trust that badgers are infected by and suffer from bovine TB.And following the BBC Panorama programme, a letter published recently in the Veterinary Times:
Similar proposals to vaccinate badgers against bovine TB in the field have been made earlier this year by the National Trust and the Gloucestershire Wildlife Trust which the President of BVA, Carl Padgett, has rightly and roundly condemned as “unrealistic at best and spin at worst”.
All parties should realise that a proven vaccine against bovine TB currently does not exist for use in the field either for cattle or for badgers. Although the injectable Badger BCG vaccine (the only vaccine licensed for use in the UK) gives a measure of protection from disease in naïve badgers following experimental challenge with live tubercle bacilli it does not prevent infection or shedding of the organism. And the vaccine has not yet been properly trialled in the field.
A small scale study on 262 animals reported last December by FERA may have shown encouraging serological evidence of vaccine efficacy but this alone cannot be regarded as evidence of protection. Protection can only be assessed by comparison of disease in vaccinated as compared to control animals in a properly controlled field trial. And this does not appear to be part of the protocols proposed by the National Trust, the Gloucestershire Wildlife Trust or the Badger Trust/NFU projects.
Vaccination is therefore currently not a realistic strategy for controlling the disease: moreover prospects for it becoming so are not encouraging. BCG has been in existence for nearly a century and attempts to improve it over the years, particularly recently, have not met with success. But even a potent proven vaccine cannot be expected to be effective in the face of the massive burden of infection that presently exists in parts of the badger population (over 30% infected in some areas). Thus unless and until this massive reservoir of infection is removed by strategic culling of badgers little or no progress will be made in controlling the disease.
There is a major flaw, amongst many, in the letter from your correspondents McGill and others (24.9.12). A proven, effective vaccine either for badgers or cattle does not exist. And the chances of one becoming available are remote. Scientists have been trying without success for over a century to improve on the BCG vaccine. Professor Boyd (chief scientific adviser to DEFRA) and Nigel Gibbens (CVO) writing in the Daily Telegraph recently (letter 22.9.12) are probably right when they say that the Badger BCG vaccine will not protect infected badgers.We have quoted Dr L.H.Thomas, MA, VetMB, PhD, FRCPath, MRCVS before, in this 2009 posting, where he discussed the use of BCG on an untested badger population.
But what we do know for certain is that the vaccine has never been proven or tested properly in the field and that the National Trust, the Gloucestershire Wildlife Trust and the Welsh Government are embarking on a highly speculative and hugely expensive strategy with little or no prospect of success.
And what we also know for certain is that culling of badgers in endemically infected areas, as demonstrated in 5 trials in England and Ireland in the 70’s and 80’s, dramatically reduces the the incidence of bovine TB in cattle. Even the seriously flawed Randomised Badger Culling Trials realised a 23% reduction in bovine TB in associated cattle herds.
Whilst we may have reservations about the effectiveness of the method of culling chosen by DEFRA in the forthcoming trials (see our letter to Vet Record 7.1.12) the choice of strategy is a no brainer – untested vaccine against proven culling strategy. All that has been lacking for the last 30 years, as pointed out by Norman Leslie in his letter to your paper (30.7.12), is the political will to do the right thing. It is to be hoped and expected that Owen Paterson MP, the new secretary state for DEFRA is of sterner stuff.
Perhaps a reason for the Badger Trust to support a PCR screen, and only jab the clean ones?