Merial anticipates delivering vaccine in regular batches over the summer, which, alongside Defra's existing contract with Intervet, will ensure that sufficient doses are available for vaccination to be rolled out across England and Wales by September.
Under EU law, vaccination is only allowed in a Protection Zone. The Bluetongue vaccination plan sets out how vaccination is being rolled out and the Protection Zone expanded county by county across England, taking into account the availability of vaccine and the level of disease risk.
Environment secretary Hilary Benn said: "Following careful assessment of tenders for Bluetongue vaccine, Defra has decided to order an additional 13 million doses. This will allow us to build on the success of the vaccination roll-out already under way and ensure we keep up momentum as we continue into the summer."
Chief veterinary officer Nigel Gibbens said: "I am pleased with the very high demand for vaccine so far. However, as we progress over the summer, the likelihood of disease re-emergence increases. We urge the industry to remain vigilant, and encourage farmers to place orders with their private vet as soon as possible."
The Merial vaccine will be available in 100ml bottles and is expected to require one 1ml dose in sheep and two 1ml doses in cattle, given four weeks apart.