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Brussels, 22 February 2006

Questions and Answers: Vaccinating poultry and other birds against Avian Influenza

What are the advantages of vaccinating birds against avian influenza?

Vaccination reduces the risk of birds becoming infected with the avian influenza virus, and lowers the chances of the virus being introduced into a vaccinated holding, as a higher amount of the virus is needed before a vaccinated bird will become infected. Vaccination also reduces the amount of the virus shed in the environment by a bird if it does become infected with avian flu, thereby helping to lower the risk of the disease spreading. A properly vaccinated flock is less likely to have an outbreak of avian influenza than a non-vaccinated flock, and if an outbreak of the disease does occur it is slower to spread and easier to contain and eradicate in a vaccinated flock. Moreover, vaccination reduces the mortality levels of infected birds, making it useful for protecting valuable birds such as zoo birds.

What are the disadvantages?

Vaccination does not provide 100% protection against avian influenza, and vaccinated birds may still become infected with the virus, depending on certain conditions e.g. level of exposure to virus. Moreover, it may mask an outbreak of the disease, thereby delaying detection and increasing the risk of it spreading. If the vaccination is not properly applied, and proper surveillance is not carried out, the avian influenza virus may continue to circulate within a vaccinated flock between not fully immune birds, albeit with a lower mortality rate. Strict surveillance and control measures must be carried out on vaccinated poultry under EU legislation, and these, along with the initial work and costs required to administer the vaccine, can make it cumbersome and prohibitively expensive when carried out on a large scale.

What does the new Avian Influenza Directive 2005/94/EC provide for regarding vaccination?

The new Avian Influenza Directive, adopted by Council in December 2005, allows Member States to carry out not only emergency vaccination (as the old legislation did), but also preventive vaccination against avian flu. Preventive vaccination must be based on a risk assessment carried out by national authorities, and will be subject to rigorous surveillance requirements for vaccinated birds. Although the new Avian Influenza Directive does not have to be implemented by Member States until July 31 2007, it entered into force in February 2005. Therefore, national authorities can already submit vaccination plans to the Commission for approval. In addition, a Commission Decision[1] backed by the Standing Committee on the Food Chain and Animal Health (SCFCAH) in October 2005, allows Member States to vaccinate special categories of birds (e.g. zoo birds) to protect them against avian flu.

What is the difference between emergency vaccination and preventive vaccination?

Emergency vaccination may be used by Member States when there is an outbreak of highly pathogenic avian influenza within or very close to their territory. It is a short term measure to contain an outbreak of avian influenza in poultry or other captive birds or to stop it from spreading from other areas where there is a confirmed outbreak. A risk assessment must show that there is a significant and immediate threat of avian flu spreading to the poultry and birds concerned, from another infected area, before emergency vaccination can be carried out. Preventive vaccination is a longer term measure, which Member States can introduce if they feel certain poultry or captive birds in certain areas would be more at risk from avian influenza should there be an outbreak. Both type of vaccination campaigns are carried out in much the same manner, and are subject to similar surveillance rules and controls.

What must a Member State do prior to carrying out a vaccination campaign against avian influenza?

Before vaccinating any birds against avian influenza, a Member State must submit a detailed vaccination plan, including details on surveillance measures, to the Commission. The Commission then reviews this plan, together with the Standing Committee on Food Safety and Animal Health. It may lay out further conditions, such as movement restrictions on live vaccinated birds, before authorising the vaccination campaign. In the case of emergency vaccination, the Member State may begin implementing the vaccination programme prior to authorisation from the Commission, provided that it issues a general ban on the movement of poultry and their product and other captive birds from the area of vaccination, and shows that vaccination is will not have a negative effect on disease control.

What surveillance and control measures have to be carried out on vaccinated birds?

Member States applying a vaccination plan must carry out intense surveillance on vaccinated poultry and captive birds, in line with the “DIVA” strategy (see below). This is to ensure that any outbreak of avian influenza in the vaccinated birds is detected quickly, despite the fact that symptoms of the disease may be less obvious than in non-vaccinated birds. Different measures can be taken to monitor for the virus in vaccinated flocks. For example, “sentinel” birds (non-vaccinated control birds) may be placed in the flock with the vaccinated birds, so that if the avian influenza virus does enter the vaccinated population, the sentinel birds will show symptoms quickly and more dramatically, warning the owner/authorities of its presence. Regular swabs can also be taken for testing from vaccinated birds to ensure that they have not become infected with the avian flu virus. Movement restrictions are placed on live vaccinated birds and their hatching eggs, and these products cannot be traded or marketed. The meat and products of vaccinated poultry can only be moved or traded if accompanied by a veterinary certificate to show that they have come from a healthy, virus-free bird. Member States using vaccination as a preventive measure must also carry out blood tests that allow the differentiation between vaccinated and infected birds.

What happens if there is an outbreak of highly pathogenic avian influenza in a vaccinated flock?

If there is outbreak of highly pathogenic avian influenza in vaccinated poultry, Member States must apply the same eradication and control measures as are carried out when there is an outbreak in unvaccinated poultry. All poultry on the infected holding must be culled, their meat and products must be destroyed, and thorough cleansing and disinfection must be carried out on the holding. A 3 km radius protection zone and 10 km radius surveillance zone must be set up around the site where the disease was detected, and wider risk areas should be marked out around these zones to act as a buffer between the affected and non-affected part of the Member State. Movement restrictions, bio-security measures and intense monitoring of holdings must be implemented in these restricted areas. (see MEMO/06/79).

Have avian influenza preventive vaccination campaigns been carried out previously in the EU?

Following a major outbreak of highly pathogenic avian influenza (but not H5N1) in Italy in 1999-2000, a targeted preventive vaccination campaign using the DIVA strategy (see below) was developed and applied. This vaccination programme has been carried out on turkeys, laying hens and poultry in certain high risk areas in the Po Valley region in Italy. The campaign has been broadly successful in dealing with certain strains of avian flu, and in containing low pathogenic avian flu viruses to prevent them from mutating into highly pathogenic strains. Special vaccination programmes were implemented to protect birds in zoos and approved centres in the Netherlands, Belgium and Germany since the major avian influenza outbreak in these countries in 2003. Other Member States have recently started applying vaccination campaigns for zoo birds in response to the heightened risk of the H5N1 avian influenza virus spreading to birds in the EU.

What is the DIVA strategy?

DIVA stands for Differentiating between Infected and Vaccinated Animals. It is a specific vaccination strategy which has been developed and applied in Italy since 2000, in regions where low pathogenic avian influenza viruses frequently occur. DIVA consists of clear measures to distinguish between vaccinated birds and those with avian influenza, who may on initial examination, be indistinguishable in terms of antibodies. The DIVA strategy requires the use of appropriate vaccines and specific discriminatory tests which enable the differentiation to be made between vaccinated and diseased birds. Such a strategy is important for detecting any outbreak of the virus in vaccinated birds, and also for trade purposes as it enables restrictions on vaccinated poultry meat to be lifted once the flocks could be clearly shown to be free of infection. The DIVA strategy has been accepted internationally as a good way to monitor and provide assurances on the health of vaccinated poultry and their products.

Why, when there is a higher risk of avian influenza, are all poultry not vaccinated in the EU?

The use of preventive vaccination requires the adoption of particular surveillance and controls to prevent the possible persistence of disease in an endemic form in a poultry population. These surveillance and controls would not be possible in case of generalised vaccination of the billions of poultry that are kept for farming purposes in the EU. Moreover, the application of the vaccination, which can require up to 3 vaccine shots per bird for it to be effective, is extremely onerous when it comes to huge bird populations.

Does the EU provide any funding for vaccination?

For emergency vaccination, the EU can provide up to 100% co-funding from the EU Veterinary Fund to cover the costs of the vaccines and their application. There is no EU funding for preventive vaccination.

Are meat and eggs from vaccinated birds safe to eat?

Yes. Firstly, before any products from vaccinated poultry can be placed on the market, the birds must be carefully tested to ensure that they are not infected with avian influenza or carrying any virus. Under EU animal health and food safety legislation, only products from healthy animals may be marketed. Moreover, antibodies created by the vaccination in live birds are inactivated at slaughter. Therefore, there is no difference in the safety of products from healthy vaccinated birds and other healthy poultry. Both the International Organisation for Animal Health (OIE) and the European Food Safety Authority (EFSA) have stated that meat and products from vaccinated poultry is safe to eat.

Are there any health threats for people working with vaccinated birds?

There is no health risk to people working or in close contact with healthy, vaccinated birds. The only risk lies in the possibility of an outbreak of H5N1 in a vaccinated flock going undetected. For this reason, strict surveillance and testing for the virus must be carried out on any birds vaccinated, and national authorities must inform poultry owners that the clinical signs of avian influenza may not be as obvious in a vaccinated flock, and therefore extra-vigilance and proper hygiene measures should be carried out.

What implications does vaccination have for EU exports?

Vaccinated poultry are subject to specific controls to ensure that they are not infected with the avian influenza virus, before their meat and products can be traded either within or from the EU. Fresh meat, meat products and table eggs from vaccinated poultry can be traded once accompanied by a veterinary certificate verifying that they have come from healthy, virus-free poultry. Vaccinated live poultry and birds, and their hatching eggs, cannot be traded within or from the EU, except under very limited circumstances. These measures are in line with the World Animal Health Organisation (OIE) recommendations. As movement restrictions are placed on live birds and hatching eggs in vaccinated zones, third country trading partners can apply a regionalised approach to EU exports of poultry and eggs.

What are implications does vaccination in third countries have for EU imports from these countries?

In terms of EU imports from third countries, live birds and hatching eggs from countries which have vaccinated against highly pathogenic avian influenza are banned. As a general rule, fresh poultry meat is not authorised either from countries which have carried out vaccination programmes against highly pathogenic avian influenza in the previous 12 months. However, the overarching principle applied by the EU is that the third countries have animal health and food safety standards equal or equivalent to EU standards. In line with this principle, special rules permitting imports of fresh poultry meat from a vaccination country might be adopted on a case-by-case basis.

This is on the condition that the third country in question can demonstrate that the animal health rules applied in its territory in relation to vaccination are equivalent to those applied by the EU. No third country where vaccination is applied has, to date, sought to export poultry or poultry products to the EU.

[1] Decision 2005/744/EC

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