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Thursday, 29 March, 2001, 12:54 GMT 13:54 UK
Q&A: The vaccination issue
Why is Britain considering vaccinating some animals against foot-and-mouth disease?
The European Union has granted Britain permission in "exceptional circumstances" to vaccinate up to 180,000 dairy cattle to create a barrier around the worst-affected areas.
The decision on whether to start vaccinating animals against foot-and-mouth will be made in the next two days, Downing Street said on Thursday.
If such a move did go ahead, said Number 10, it would only be in Cumbria, the worst-affected area.
European governments have resisted vaccination because the test for foot-and-mouth disease cannot tell the difference between a vaccinated and an infected animal. This means that countries that vaccinate lose their disease-free trading status on world markets. This could deny Britain up to £1.3bn a year in exports.
How effective is vaccination? Will vaccinated animals have to be slaughtered?
National Farmers' Union President Ben Gill has warned that a vaccination programme would never be 100% effective.
He said vaccination could only be one of the measures to contain the spread of the disease in hotspots, adding that vaccinated animals would still have to be culled.
Others say this issue is not so clear, arguing that mass vaccination could take the place of the government's programme of mass slaughter, which has seen three-quarters of a million animals, many of them healthy, condemned in a bid to stop the disease spreading.
But it is difficult to see what economic value vaccinated animals would have to farmers.
Under what circumstances could vaccination be used?
The UK, together with other European countries, has large quantities of vaccine for all the main types of the virus. This can be deployed in an emergency, if the epidemic gets out of control.
This would then ease the problem of coping with the large numbers of animals destined for immediate slaughter.
Dairy cattle in Cumbria are being considered for vaccination because they have been kept in barns over winter and have not been exposed to the virus in the same way as sheep. In the next month, the cattle would normally be put out to pasture. Vaccination could therefore protect them from picking up any infection that may be in the fields.
There seems little point in vaccinating the sheep in Cumbria, especially since many of the animals may already be incubating the disease.
EU veterinary officers have already agreed to limited, emergency vaccination in the Netherlands to fight the spread of the virus.
A European Commission study into the costs of vaccination found that it would be cheaper in the long term to slaughter rather than to vaccinate. Until now, most of the EU countries have backed the European Commission, which believes the disadvantages of vaccination far outweigh the benefits.
How does the vaccine work?
It is made by deactivating the live foot-and-mouth virus. The vaccine is harmless but still triggers an animal's immune system to make antibodies against the disease. There are seven varieties or serotypes of foot-and-mouth, and a specific vaccination is required for each one. The virus involved in the UK outbreak is a serotype O virus and was first isolated in northern India in 1990. It is referred to as the Pan-Asian virus.
How effective is the vaccine?
It takes 10 to 14 days to become effective and even then does not offer complete protection. The virus responsible for the current outbreak is highly virulent and, in high enough concentration, could overwhelm the protection offered by the vaccine. And a vaccinated animal which did contract the disease might not show many symptoms but would still pass the disease on.
How easy is it to make?
Bayer AG in Germany says it can make 100,000 doses in 24 hours and a million doses in five days. To make the vaccine, cells are grown in the lab and then infected with the foot-and-mouth virus. Chemicals are used to make the virus inactive. Strict precautions are needed to contain the active virus during the manufacturing process.
Around half a million doses of the vaccine for each serotype are stored in the UK.
Are new vaccines in the pipeline?
Experimental synthetic vaccines are being developed but they are not approved for use. If they were used, it might be possible to tell the difference between vaccinated herds and infected herds, but it is not clear whether they would be any more effective in tackling the disease on a national scale.
US researchers are also working on a test that can tell the difference between an animal that has been exposed to the virus and one that has simply been vaccinated.
19 Mar 01 | UK
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