Emergency vaccination against classical swine fever.

At present, emergency vaccination against classical swine fever is not practised in Western countries. However, stamping out and pre-emptive culling policies are increasingly meeting greater resistance. Consequently, emergency vaccination is a re-emerging subject of debate. There are highly efficacious classical live vaccines that induce early immunity, but their use precludes the serological discrimination of infected and vaccinated pigs. Therefore, E2 subunit DIVA vaccines have been developed that allow this discrimination. However, their efficacy is lower than that of the live vaccines and the companion diagnostic differential test, the E(rns) ELISA, has its limitations. Modern biotechnological methods enabled researchers to develop a variety of candidate vaccines that have been shown to induce immunity in pigs. However, it is not expected that one of them will enter the marketplace in less than five to 10 years. The current vaccines should therefore be used, if emergency vaccination programmes to eradicate classical swine fever are to be implemented in the near future. Two possible scenarios for emergency vaccinations are discussed.