Use of vaccination in avian influenza control and eradication.

Vaccination against avian influenza (AI) infections caused by viruses of the H5 and H7 subtypes has been used in several occasions in recent years with the general objective of controlling and in some cases eradicating the disease. To contain AI infections effectively, vaccination should only be used as part of a comprehensive control strategy that also includes biosecurity, quarantine, surveillance, education, and elimination of infected and at-risk poultry. Although properly used, potent AI vaccines can prevent disease and death, increase resistance to infection, reduce virus replication and shedding, and reduce viral transmission, they cannot completely prevent AI virus replication. A wide variety of vaccines against AI has been developed and tested in experimental conditions, but only inactivated whole AI virus vaccines and recombinant H5-AI vaccines have been licensed and widely used in various countries. AI vaccination programmes should be adapted to local conditions to guarantee efficacy and sustainability. In particular, vaccination programmes should be modulated in diverse situations according to the virus strain involved, the characteristics of the poultry producing sector, the capacity of the veterinary infrastructure, and the availability of adequate resources. Based on the eco-epidemiological situation in the affected region/area/compartment and the assessment of the risk of AI introduction, different vaccination strategies could be implemented to control AI: (i) routine vaccination performed in endemic areas; (ii) emergency vaccination in the face of an epidemic; and (iii) preventative vaccination carried out whenever a high risk of virus incursion is identified.