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-------- Original Message --------
Subject: H5N1: Appeal to Veterinary Profession
Date: Thu, 02 Mar 2006 13:26:05 -0800
From: "Stephen M. Apatow" <>

IDIN Communication: International Veterinary Public Health Consortium
Subject: Pandemic Influenza: Contingency Planning discussion

Dear Colleagues:

Discussion associated with depopulation of the zoo animals in Sweden has been met with horror by members of the veterinary profession across the globe.  Once again:

Depopulation of all the birds at a zoo, if one positive confirmation of a pathogen is isolated in migratory birds, demonstrates the level of insanity that exists even on the veterinary public health level.  Depopulation estimates of 1.5 - 2.0 billion birds demonstrates the same logic applied during the 2001 UK FMD outbreak, except this containment strategy has not worked, despite aggressive efforts to mediate contingency planning during the last three years.

Destruction may work when dealing with an early outbreak of an exotic disease.  However after three years of utilizing this WHO-FAO approach, H5N1 has spread from part of one continent to three continents.  MADNESS!  It's time for a better approach. --  Depopulation of Zoo Animals, God forbid,  David Halvorsen (former President, American Association of Avian Pathologists (1993Ė94) , Diplomate, ACPV, College Of Veterinary Medicine, University of Minnesota).

We must establish the correct policy directive before this challenge escalates.

Two requests:

1.  Review a veterinary statement regarding the 2001 UK FMD disgrace, by Willem Schaftenaar DVM, Rotterdam Zoo and Chairman of the Committee of Zoo Veterinarians of the Royal Dutch Veterinary Association. Rotterdam, March 21, 2001:

2.  Review:   Ellis TM et al. Vaccination of chickens against H5N1 avian influenza in the face of an outbreak interrupts virus transmission. Avian Pathology, 2004, 33(4):405Ė412.


Vaccination of chickens with a commercially available killed H5N2 vaccine was being evaluated as an additional tool to enhanced biosecurity measures and intensive surveillance for control of highly pathogenic avian influenza subtype H5N1 disease in Hong Kong in 2002. In December 2002 to January 2003, there were outbreaks of H5N1 disease in waterfowl in two recreational parks, wild water birds, several poultry markets and five chicken farms. In addition to quarantine, depopulation of the affected sheds and increased biosecurity, vaccination of the unaffected sheds and surrounding unvaccinated farms was undertaken on three farms. In at least two farms, infection spread to the recently vaccinated sheds with low rates of H5N1 mortality in sheds when the chickens were between 9 and 18 days post-vaccination. However, after 18 days post-vaccination no more deaths from H5N1 avian influenza occurred and intensive monitoring by virus culture on these farms showed no evidence of asymptomatic shedding of the virus. This provides evidence that H5 vaccine can interrupt virus transmission in a field setting.

Full Paper: PDF

The following dialogue might also be of interest.


Humanitarian Resource Institute
Stephen M. Apatow
President, Director of Research and Development, Humanitarian University Consortium Graduate Studies Center for Medicine, Veterinary Medicine and Law

Tel: (203) 668-0282

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March 2 2006 from Jim Hungerford, General Manager of Intervet UK

Revised:  1 March 2006

Poultry vaccination is vital to control avian flu

As the UK government takes precautionary measures and places an order for over 2 million doses of Nobilis Influenza, the only vaccine licensed in the UK to protect birds against the H5N1 avian flu strain, Intervet UK sets out the argument for vaccines.   General Manager of Intervet UK, Jim Hungerford, answers some of the topical questions.

1. Why do you have a vaccine for the H5N2 strain of avian flu when it is the H5N1 strain that is causing the problem?

Intervet produces a H5N2 vaccine, which is closely related to the present H5N1 strain so that it induces protection, but also allows differentiation of vaccinated versus infected birds.

2. How quickly will the birds be protected after vaccination?

Birds have to build up immunity following vaccination. We have indications that the protection starts 1-2 weeks post vaccination. After 3 weeks, there is significant protection that peaks at approximately 5 weeks after vaccination. The duration of protection is increased to one year by re-vaccinating 4-6 weeks after the first vaccination.

The first injection will provide protection against clinical disease from at least 2 weeks onwards and reduce excretion of virus dramatically.   As a result, it will reduce the spread of disease and, for the few birds that do get infected the amount of virus produced will be drastically reduced.

3. Are there any vaccination methods other than injection?

The vaccines currently used are inactivated vaccines, which means that the virus is inactivated (not live) and in order to get a good immune response the vaccine has to be injected.  Intervet is investigating the possibilities for mass application, which could be for example spray or water application. However, this does require developing a new type of vaccine, e.g. by applying biotech methods. Research projects are in an early stage and it will take time before such a product can be registered and then brought to the market.

4. How can vaccinated animals be differentiated from infected animals?

Intervetís vaccine is based on a different strain (H5N2) than the current field strain (H5N1).  Because the vaccine is based on a H5 strain it fully protects against all H5 viruses. If you vaccinate with H5N2 you get extra antibodies in the vaccinated animals (against the N2) that you donít get if birds get infected with H5N1. You can monitor these antibodies with a number of standard methods.

5. Does the vaccination mask field infection?

No.  Vaccinated chickens may rarely still become infected. A minority of these few chickens may still excrete a very limited amount of virus.  However, the amount of virus is too small to infect other birds.   The excretion is so limited that it does not lead to the transmission of the virus.

In Hong Kong, Intervetís vaccine has been used extensively on infected farms.  On these farms virus transmission was blocked completely from 18 days after vaccination.  Vaccinated birds no longer transmitted the virus and did not turn into carriers.

Further information is available on our dedicated website

6. How is avian flu transmitted from bird to bird and from birds to humans?

Infected birds excrete high amounts of virus in their droppings, which facilitates further spread. Bird to bird infection mainly occurs by inhaling the virus whilst breathing.   From poultry house to poultry house the virus is transmitted mainly by contact with contaminated equipment and/or movement of birds and people.   People can be become sick when they are exposed to a large amount of virus caused by intensive contact with infected birds.

7. Is it safe to eat birds vaccinated with inactivated AI vaccine?

Yes, it is perfectly safe.   To keep birds healthy, all of our commercial British poultry are vaccinated routinely against various diseases, so of course poultry products from those vaccinated birds are safe for consumption. This is the same for birds vaccinated with Nobilis Influenza.  The withdrawal period for the vaccine is zero days. (The withdrawal period is the time which passes between the last dose of a medicine given to the animal and the time when it can be used for human consumption).

Therefore, it is both safe and effective for poultry to be vaccinated and safe for people to eat birds that have been vaccinated.  There is also no risk associated with eating eggs from vaccinated hens.  It is important to emphasise that avian flu cannot be passed on by eating poultry or eggs.

Statement from an independent third party

The Netherlands Nutrition Centre (Voedingscentrum) states that eating prepared chicken meat and eggs is safe even when avian flu is prevalent. This also applies when it comes from chickens which have been vaccinated against avian influenza. The virus can only infect people who have intensive contact with sick or dead birds.

Moreover, the Government will make every effort to ensure the virus is not present in chickens and eggs that are sold. This will not only protect the consumer but will also prevent the spread of the disease. In the hypothetical event that infected chicken meat or eggs would be sold the virus will not survive cooking.

8. Do you make vaccines for avian flu regularly?

Yes, we produce vaccines on a regular basis to protect birds against Avian Influenza caused by different strains occurring more frequently such as H9, H5, H7.

9. How much vaccine do you have available? How quickly can you supply? Is it enough for the countries affected now?

We produce the vaccine in question on a regular basis. We have sufficient stock to support our regular sales. In case of a sudden substantial increase in demand we still can increase our production. However, delivery can vary from a few weeks to some months. This depends on the stage of the production process, orders that have been placed and our current stock situation. We can only supply if we receive official orders. We cannot guarantee immediate supply if demand is growing.

Britainís first shipment of Nobilis Influenza vaccine will arrive by mid March.

10. How long does it take to make new batches of vaccines?

It normally takes months to start from the suitable antigen in stock before you have produced a batch and you then have to run all required quality control tests. Even if you speed up production as much as possible, it will still take several weeks to get a batch produced ready for tests.

Testing of the vaccine has to be done according to European Regulations on antigen and final product. In case of an emergency, testing of the final product can (partially) be waived with approval of the UK authority, and if so the product may become available earlier.

11. Where is your avian flu vaccine made? Intervet routinely produces AI vaccines in Spain and Mexico.

12. How are the birds actually vaccinated?

Birds are vaccinated by injection under the skin or into the muscle.

13. How much does it cost to vaccinate?

The vaccine costs around three pence per dose, which equates to six pence per bird, as they need two doses.  There are also associated labour costs for administering the vaccine.

14. What is your recommendation regarding vaccination?

Intervet is recommending that the UKís free range hens (approximately 9 million) and other outdoor birds are vaccinated to help in the fight to keep avian flu out of the UKís poultry flock.

15. Wouldnít it be cheaper just to move the free range hens indoors?

While this is a good theoretical solution, we believe that it would be impossible to achieve in reality without serious welfare implications.  Some free range farmers will not have the facilities to do this and hens that are not used to being kept in close proximity have a tendency to fight.  A pro-active vaccination policy will also help avoid the need for millions of birds to be destroyed should an outbreak occur.

16. Germany has reported a suspected case of a cat infected with bird flu  strain H5N1. Can cats be vaccinated against bird flu? Do you have a suitable vaccine?

During the 2003 to 2004 outbreak of avian influenza A (H5N1) virus in Asia, fatal infection in domestic cats was reported. Studies at independent institutes* have also shown that domestic cats are at risk of disease or death  from the H5N1 virus and therefore it has been advised that cats in infected
areas should be kept away from contact with wild birds or domestic poultry.  As Avian Influenza has not been found in the UK we do not recommend that  owners of domestic cats take any new precautions.

Intervet does not currently have a vaccine available to protect cats against the H5N1 virus, however preliminary studies have suggested that it may be possible to develop a suitable vaccine for use in this species.

The Intervet Nobilis influenza vaccine developed to protect birds is not designed (and not licensed) for use in cats, which are more sensitive to the
adjuvant used.