Professor David King, Government Chief Scientist
Miriam O'Reilly (Q) - I asked Professor King if cattle, which are soon to be turned out on to spring pasture, were vaccinated could they still carry the disease?
Professor King (Prof K) - "I'm very glad you've asked me that question because I think that there is an enormous amount of misunderstanding on this very issue. The cattle that are vaccinated with this high-potency vaccine that is available... would be able to face a very severe challenge of foot and mouth virus and therefore would not pick up the disease. They would develop antibodies which would stop the virus going into their bodies and virus would not go into their milk. The virus is carried but only in the region of the throat of the animal and the rate of infection of other animals from an animal which is carrying it in this way is very, very low indeed. There are one or two reported cases around the world and there's been a very long history of foot and mouth disease - one or two cases only where disease has been shown to have been spread from such carriers.
Q: If they can carry disease in their throats does that mean that they could breathe it out?
Prof K -Yes, but what I am really going to stress here is that because of the anti-body development in the body of the cow the virus can never build up to a significant enough level to amount to a significant challenge to another animal and so the possibility of passing the disease on to another animal is extremely low.
Q: Science is never an absolute so can you say to farmers that there are no risks at all with passing the virus from vaccinated animals?
Prof K -You have phrased your question absolutely correctly - science sometimes does deal with absolutes but when we're dealing with complex phenomena of this kind we're dealing with statistics and what I've just said to you is as accurate a statement as I an make. I was in other words a betting person I would say that from the vaccinated cattle, if we vaccinated all the living cattle in Cumbrian barns today, from those vaccinated cattle would bet that we would not spread the disease at all.
Q: Why then do you think the NFU and many farmers who have contacted this programme are against vaccination?
Prof K - Well let me say that in the last three days I have spent a considerable amount of time talking to members of the farmers union, talking to farmers and talking to vets and I've received a lot of extremely useful information from people who work in the field with these animals and they, I hope, have received useful information from us. I think there has been, as always happens in situations of this kind, an awful lot of misunderstanding about the science of the disease and the question that you asked me about the carrier state, and the way scientists use the phrase carrier state, is perhaps the most confusing of all.
Q: Would animals have to be vaccinated continually over that 6-month period, or would one vaccination do it?
Prof K - This high-potency vaccine being held at Pirbright would only need to be administered once to a herd and only once and within three to four days the antibodies would have developed in the animal and we would say keep the cattle in barns, if they are already in barns, for a week after the vaccination and when they're let out then the animals exposed to virus would not become diseased. Now your question is should this be repeated and it is true that the antibody level in the animals dies off with time and, so roughly six months later a booster vaccine would be needed if vaccination was still required. But let me stress that the way the epidemic is going and the way it is now under control, my belief is that in sixth months time there would be no need to re-vaccinate these animals because we would be getting rid of the disease. Q: And finally, Professor, one last question. Business leaders are saying that this epidemic could cost the country £40 billion if it's still around in July - are we going to be in the same situation in July, do you know?
Prof K - We're not going to be in the same situation in July - let me be uncharacteristically dogmatic about that. I think that when we say that the epidemic is coming under control, we have a high degree of confidence in that. Surveillance and culling must continue at the present level but if we do that then I'm really quite confident that come the summer this epidemic will be stuttering along but at a very slow rate.