Avian flu: Will inoculations beat the disease, and why is Britain so opposed?

No specific vaccine has yet been made for the H5N1 strain of bird flu. But a general inoculation, covering the H5 and H7 variants of the virus, has long been available and would be effective against H5N1 in birds.

What is preventive vaccination?

Under plans put forward by the French and Dutch governments, free-range birds with access to pasture would be vaccinated against the flu virus to prevent infection from wild birds and contaminated feed. Mass vaccination of all poultry, including battery hens, is also being considered in the Netherlands.

Who orders a vaccination programme?

Emergency vaccination can only be carried out with the approval of the EU. Ministers from the 25 EU nations will meet today to discuss whether France and the Netherlands - Europe's two largest poultry producers - can proceed with large-scale inoculations.

How many birds would be involved and how much will it cost?

French proposals would involve vaccinating every bird within a designated "buffer zone" around the site of an outbreak. This would be widened to a general vaccination campaign, involving hundreds of millions of birds, under Dutch plans. Britain alone has some 25 million free-range birds. The cost of vaccination in the UK would be around £10m.

How long will it take?

A large-scale vaccination programme presents major logistics problems. The vaccine must be applied to each bird twice within a period of three weeks and then boosted every six months. The EU has voiced doubts that the vaccinations can be administered quickly enough to be effective.

Will it work?

The vaccine will be effective in protecting birds if they are infected with H5N1. But this leads to additional problems - the vaccine does not prevent birds replicating the virus and spreading it to other birds, in particular wild birds which can spread the disease further. It also makes it difficult to differentiate between a bird producing antibodies from a vaccine and a non-vaccinated bird infected with H5N1.

Does Britain differ from other countries in its proposals for use of a vaccine?

Yes. As with the foot-and-mouth disease outbreak in 2001, Britain prefers to use vaccination only as a last resort, while countries such as France and the Netherlands seek to use it earlier and more widely. Vaccination affects export sales by removing the disease-free status of a country.

Is there enough vaccine?

Not necessarily. Unlike the Netherlands, Spain or the US, Britain does not have a bird flu vaccination "bank".

The Government says such a stockpile is unnecessary as only a limited vaccination campaign to "ring fence" outbreaks would be contemplated. But serious questions remain over whether such a limited vaccination could be completed in the short term if Britain's EU partners do not have enough stockpiled vaccine to share.