MEMO/06/92
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 Decision1 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.
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Decision 2005/744/EC
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.
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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.
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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 caseby-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.
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