Avian influenza: post-vaccination surveillance key for safe movement of birds

EFSA was asked to give a comprehensive overview of effective surveillance options and risk reduction measures for avian influenza. Our scientists assessed these measures and evaluated whether the available surveillance strategies could demonstrate freedom from the disease thereby enabling the safe movement of poultry and related products.  

Our experts looked specifically at surveillance strategies for emergency and preventive vaccination scenarios, setting out the target species A subdivision of the genus, a species is a group of closely related and similar-looking organisms; for example, in the case of Homo sapiens (humans), the second part of the name (sapiens) represents the species. of poultry (layer chicken, turkey or duck), the number of animals to be tested, the diagnostic method, and the sampling period.  

In the case of emergency vaccination for highly pathogenic avian influenza (HPAI), our scientists concluded that surveillance schemes for the early detection of new outbreaks should consider the poultry type and flock size to be effective. If vaccination is preventive, to prove the absence of the disease monthly virological testing of up to 15 dead birds is recommended to safeguard the movement of poultry and related products. Also, both vaccinated and unvaccinated flocks should be subjected to passive surveillance The reporting and investigation of increased mortality, other signs of serious disease or significantly reduced production rates with an undetermined cause in a targeted animal population. 

Experts from the EU reference laboratory and EFSA worked closely to recommend the most appropriate diagnostic tests for surveillance according to vaccine type, vaccination strategy (i.e. emergency or preventive), and the scope of the surveillance. More sensitive methods should be used when the amount of virus in the blood is likely to be low due to vaccination.  

“Vaccination is an important tool in the fight against avian influenza and is recommended as part of an integrated disease control approach. Nonetheless, there is a need to follow up with a strategic surveillance scheme and implement measures to reduce the risk of virus transmission” said Frank Verdonck, head of EFSA’s Biological Hazards and Animal Health and Welfare Unit. “Maintaining a high level of biosecurity remains essential, even when vaccination is used. Raising awareness among farm owners and practitioners can help to ensure that any changes in poultry production or increased mortality are promptly reported and acted upon”, he continued.  

In a previous opinion, published in October 2023, EFSA gave its scientific advice on available HPAI vaccines for poultry and suitable vaccination programmes. EFSA’s advice will help inform decisions by risk managers at a European and national level on effective surveillance strategies to implement in vaccinated areas and on farms, both for the early detection of HPAI outbreaks and to demonstrate freedom from the disease.