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The British Veterinary Association

Statement on the Use of Vaccination as a Control Option for Avian Influenza

http://www.bva.co.uk/policy/issues/AI_vaccination_statement.pdf

Or see below for full text. Extract:

The BVA supports the use of vaccination under the following circumstances:

Extract 2 ".....
  • Wild bird surveillance should be stepped up immediately across the EU to ensure rapid detection of the virus and to assess the real level of infection across Europe
  • Vaccination should be considered as part of the future control of the disease when it is identified in the UK in wild birds or domestic poultry
    therefore:

    ................

     

    Statement on the Use of Vaccination as a Control Option for Avian

    Influenza

    The BVA supports the possible use of vaccination as part of a national control plan for avian

    influenza, but would like to stress that there are many issues that need to be taken into

    account when considering the use of vaccines for disease control. The BVA does not support

    the use of vaccination in domestic poultry before avian influenza is identified in the UK.

    Disease Status

    At present (24/02/06):

    No cases of highly pathogenic avian influenza have been detected in wild birds within the UK.

    To date only one case of H5N1 has been confirmed in ducks and chickens in an animal

    sanctuary in Austria (the first EU case in poultry). One suspected case of highly pathogenic

    avian influenza is also under investigation in domestic poultry premises in the EU (France).

    Migratory waterfowl, believed to be associated with the spread of H5N1 are now travelling

    eastwards, away from the UK

    Statement

    The BVA believes that under the current conditions, it is not yet appropriate to carry out

    preventative vaccination of the UK’s domestic poultry flocks as it may severely compromise

    the ability to recognise and react quickly to any introduction of the virus to our domestic

    poultry.

    The observed, limited transmission between wild birds and poultry within the EU countries to

    date is encouraging and the UK may be able to control this disease by limiting contact

    between wild birds and domestic poultry and through early detection and ‘stamping out’

    (culling of infected or close contact birds).

    It should be recognised however that these control measures may not remain the

    most appropriate option if either:

    o the level and duration of infection in the wild bird population increases

    significantly or

    o the risk of transmission to domestic poultry increases significantly.

    Thus constant surveillance of the disease is necessary and vaccination should always be

    considered as a control option for the future. The UK must be prepared to react immediately

    to any change in risk that will necessitate the use of a vaccine, and we must ensure that the

    UK has the necessary measures in place in order to allow us to respond effectively.

    The BVA recognises that considerable surveillance has taken place in the UK since October

    2005 but we strongly urge Defra to continue to step up surveillance in wild birds. This will

    ensure that highly pathogenic avian influenza is detected at the earliest opportunity to ensure

    that isolation and eradication is immediate. We must also ensure that efforts are made to

    determine the level of infection in wild birds across Europe as this will have an impact on the

    level of risk posed to the UK.

    Defra should now, with urgency, be submitting all necessary vaccination plans to the

    European Commission so that, when it becomes necessary, EU approval for the use of

    vaccination can be sought and acquired quickly.

    24/02/06

    The statement below outlines the pros and cons of vaccination from a veterinary perspective

    and outlines the types of vaccination that are felt to be appropriate and under which

    circumstances. It also reinforces the need to continually monitor the spread of this continually

    changing disease.

    Summary

    • We do not support vaccination of domestic poultry before avian influenza is identified in

    the UK

    • Early detection, isolation and eradication is the best approach to controlling the spread

    of this disease

    • Poultry owners should be making efforts to protect their flocks by preventing contact

    between poultry and wild birds and their droppings by:

    o Increasing biosecurity measures

    o Keeping domestic birds away from lakes and waterways

    o Feeding and watering domestic poultry indoors

    o Preparing to house free-range birds within 24 hours should Government

    demand it.

    • Wild bird surveillance should be stepped up immediately across the EU to ensure rapid

    detection of the virus and to assess the real level of infection across Europe

    • Vaccination should be considered as part of the future control of the disease when it is

    identified in the UK in wild birds or domestic poultry therefore:

    o Defra’s contingency vaccination policy should be finalised immediately

    o The vaccination plans should be submitted to the EU Commission before

    seeking approval to actually start vaccinating

    o A vaccine order should be placed in line with the UK’s contingency plan

    o The contingency vaccination plans should be re-examined daily/weekly

    • Vaccination can be an important additional measure but it does not prevent infection so

    vaccinated birds must be subject to continued monitoring for the virus. Biosecurity

    measures must be maintained in vaccinated birds.

    • We support the vaccination of high risk birds, from zoos or private bird collections,

    which cannot be moved indoors for welfare reasons.

    Supporting comments: The use of vaccination to control the spread of avian

    influenza

    Vaccination is not a solution in itself and should be used in conjunction with other control

    measures, which include heightened biosecurity, movement controls and culling or ‘stamping

    out’ in control zones (3 km and 10 km) around any disease outbreak.

    Biosecurity measures are essential to control an outbreak as avian influenza will still be able

    to spread with or without vaccination. The use of a vaccine would also have to be

    accompanied by increased surveillance and monitoring of the vaccinated birds, in order to

    pick up any superimposed infection within a flock.

    24/02/06

    It is necessary to be able to differentiate vaccinated and infected birds from those that are

    merely vaccinated. Current vaccines allow for such a ‘DIVA’ (differentiating infected from

    vaccinated individuals) strategy to be followed. However, their effectiveness, and the

    possibility of following a ‘DIVA’ strategy will depend on the type of vaccine and the current

    strain of the avian influenza virus circulating. Sentinel (unvaccinated) birds should also be

    used to test for any infection in a vaccinated flock.

    Vaccination can be used in two ways as part of a control strategy:

    • As a preventative measure prior to the detection of the virus

    • Or as an emergency control measure for use once the virus has been detected.

    The UK Government has outlined plans for both applications in their draft vaccination plan,

    which is part of the UK’s transposition of the AI Directive into UK law. The BVA is fully

    supportive of keeping every available disease control option open for the future and endorse

    the consideration of both applications for disease control.

    Vaccine Limitations

    There are limitations with the current vaccines available. They are inactivated and need to

    be injected into each individual bird, and vaccination will probably have to be administered on

    two occasions. This makes vaccination a very expensive exercise in terms of manpower and

    time. It normally takes from 2-5 weeks for the birds to build up the necessary level of

    immunity. Vaccination can also have an effect on the welfare of layers; handling depresses

    egg production and can result in peritonitis (an inflammation of the peritoneum, the

    membrane that lines the wall of the abdomen and covers the abdominal organs) which can

    be fatal.

    The current vaccines also do not protect birds from becoming infected with AI, nor do they

    prevent such vaccinated birds from excreting the virulent virus. However, trials indicate that

    the quantity and duration of such excretion are considerably reduced. Confirmation of the

    presence of virus (with or without overt signs of disease) will trigger the slaughter of infected

    flocks and the establishment of a 3km protection zone and 10 km surveillance zone. It must

    also be stressed that vaccination against one strain of the virus will not protect the UK flocks

    from the introduction of another strain of the virus, which for a rapidly mutating virus is a

    significant factor to consider.

    The advantages of vaccination

    The advantages of vaccination in terms of disease control are that it significantly reduces the

    clinical severity of the disease and the transmission of the virus between birds. Therefore

    vaccination has the ability to reduce the spread of infection in birds, and to reduce the risk to

    those working with poultry. It would also provide some protection for free range flocks that

    cannot be held indoors for a protracted period.

    Vaccination in other EU Member States:

    From the latest information available, France and the Netherlands have recently been given

    permission to begin vaccination programmes.

    Defra update 23/02/06 on the SCoFCAH meeting on vaccination (21 - 22 February)

    At the meeting the Netherlands and France submitted detailed plans which were agreed.

    This is a summary of them.

    The Netherlands proposed to immediately vaccinate all backyard flocks and free range laying

    hens over seven weeks old (up to 8 million birds). This was due to their view of the high level

    of risk across their territory with a very concentrated poultry population, extensive aquatic

    area and being a cross roads for several main migratory routes for wild birds and the

    impracticality of housing;

    24/02/06

    France proposed to vaccinate from March just geese and ducks over 3-4 weeks old (around

    900,000 birds) in three Departments on the Atlantic coast (that is not including the area

    where there has been an outbreak) which they assessed as high risk for similar reasons

    around migratory routes, high density and aquatic areas.

    France and Denmark also circulated plans to vaccinate zoo birds (following plans already

    submitted by the Netherlands, Belgium and Portugal) and Sweden also announced its

    intention to do so.

    BVA supports the use of vaccination under the following circumstances:

    • Vaccinating high risk birds, from zoos or private bird collections, which

    cannot be moved indoors for welfare reasons.

    • Where there is a high risk of spread of the highly pathogenic avian influenza virus

    to the UK.

    • Preventative vaccination in high risk areas where it is felt impossible to

    maintain adequate separation of domestic flocks from a high density of wild birds

    suspected of carrying AI, (based on a risk assessment).

    • Emergency vaccination as a disease control option where other control

    methods have failed to contain the further spread of infection, or for high risk

    groups in the near vicinity as detailed above if preventative vaccination has not

    already been considered

    • If the level of culling as a control method reaches such a level as to be

    unjustifiable on ethical or welfare grounds, as has now been declared in the

    Asian context by the WHO, OIE and FAO.

    • If the disease becomes endemic in the UK and persists at high levels in the wild

    bird population.

    • Where the welfare of birds is considered to be severely compromised; for

    example, free range flocks that are required to be housed indoors for long periods.

    Vaccination would allow the birds to be returned outdoors and they should be

    constantly monitored (use of sentinel birds).

    Vaccination of zoo birds:

    The collective term ‘zoo birds’ is used to include rare and endangered species housed in

    zoological and private collections. The justification for the vaccination of zoo birds and private

    collections is a separate issue to the vaccination of domestic flocks and BVA, BVZS (British

    Veterinary Zoological Association) and BIAZA (The British and Irish Association of Zoos and

    Aquariums) believe that in order to preserve biodiversity such collections should be

    vaccinated. Many species cannot be held indoors or adequately separated from wild birds

    without severe consequences to their welfare.

    Any use of vaccine in this scenario would not be to control a disease outbreak but as a

    conservation measure for rare and endangered species. Contingency planning of this sort is

    consistent with both UK and EU policy. Given that current information indicates that some

    larger zoo birds may require a second vaccination three weeks after the first and that the

    maximum protective effect may take up to 5 weeks, this means it could take up to 8 weeks to

    protect a zoo bird using vaccination. Consequently, the BVA, BVZS and BIAZA believe that

    Defra should now be seeking EU agreement to our vaccinating high risk birds from zoos and

    private collections.

    Decision-making on the birds to vaccinate and methods of monitoring should be made on a

    case by case basis taking into account welfare and physical practicalities as well as previous

    data available about the use of such vaccines in zoo birds; consultations between zoo

    veterinary professionals and Defra should inform decision-making in this area. Vaccination of

    individual zoo birds should take into account the following areas:

    - The concept of epidemiological units

    - Bird eligibility

    - Vaccine logistics

    - Implementation of vaccination

    - Surveillance and testing – along with the use of a ‘DIVA’ strategy

    Vaccination of non-domesticated species is not without risk to the birds as they are not used

    to being handled and to be done safely it will take time. The birds will have to be caught at

    least twice for the first and second injection which is considered to be a very stressful

    experience for many species.

    Vaccination has produced lethal effects in some zoo birds and we do not know how many of

    the species will react to the vaccine. Therefore veterinary zoological experts should be

    consulted on the use of vaccine for the different species kept.