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Jim Hungerford, General Manager of Intervet
UK
Press release and Q&A's that we have sent out here in the UK about
vaccination.
Our position is that zoo and free range birds should receive preventative
vaccination. Our reasoning is that these are the birds most at risk and
they are solidly protected for 12 months after the two doses of vaccine
- if they are exposed to any virus it will not become established or be
transmitted (as exposure is an unpredictable risk with migrating waterfowl,
we believe vaccination should start now to ensure these birds are protected
as soon as possible). The use of non-vaccinated sentinel birds and antibody
(DIVA) testing provides the appropriate assurance of vaccination, non-exposure
and non-infection. The government proposal of waiting for an outbreak
will require slaughter of the exposed birds (clearly unacceptable in a
zoo situation) and the emergency vaccination and quarantine in the surrounding
zone. If despite this the infection spread, I can't see society accepting
a repeat of the terrible scenes that we saw during the FMD crisis, and
I hate to think what it would do to our agriculture. Also, the proposal
to house free range birds for months in buildings that are only designed
for overnight use poses major animal welfare problems. Finally, emergency
vaccination (with a single dose) is never as good as the full course of
two doses.
To my understanding, there are no 'silent carriers'. When our vaccine
is used as recommended (2 doses 4-6 weeks) apart it prevents transmission
of the disease, even with the high challenges used experimentally. The
reason for this is that the very few birds that do get infected from the
experimental challenge shed extremely small amounts of virus - 10,000
to 100,000 times less - and that these minute amounts of virus are too
small to infect other birds. The infection then dies out - no new birds
get infected, and the few infected birds (which are not clinically sick)
recover and clear themselves of the infection.
I think the differences are between what is measurable (in any field you
can typically find something out of the ordinary if you look with extremely
sensitive techniques), versus what is significant in the real world.
The demonstration of this is what happened in Hong Kong during their outbreak.
Vaccination, as part of a very stringent overall control program, stopped
virus circulation on infected premises from 18 days after the vaccination
started. Importantly, carriers were not found. These findings are reported
in the publication. ( "Vaccination of chickens against H5N1 avian
in?uenza in the face of an outbreak interrupts virus transmission"
Avian Pathology (August 2004) 33(4), 405 /412 )
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?
Intervet's 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 don't 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, Intervet's 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 http://www.avian-influenza.com/
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.
Britain's 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 UK's free range hens (approximately
9 million) and other outdoor birds are vaccinated to help in the fight
to keep avian flu out of the UK's poultry flock.
15. Wouldn't 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 riskof 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.
*(Rimmelzwaan et al_ 168 (1) 176 - American Journal of Pathology; Kuiken
et al Avian H5N1 influenza in cats Science 2004; Brown 168 (1) 6 - American
Journal of Pathology)
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For further press information, please contact:
Cordy Maling or Diana Rhodes.
Blue Zebra PR. Mobile contacts: (CM) 07710 987427 or (DR) 07767 370148
Tel: 01235 833005 Fax: 01235 833006
Email: cordy.maling@bluezebrapr.com or diana.rhodes@bluezebrapr.com
23 February 2006 Poultry vaccination is vital to control avian flu
Britain's first consignment of Nobilis Influenza vaccine - the only vaccine
licensed in the UK to protect birds against the H5N1 avian flu strain
- will arrive mid March. Over two million doses have been ordered by the
Government to be held in reserve as a conservation measure for UK captive
rare and endangered species of birds, such as the Tower of London's iconic
ravens.
Intervet, the world's largest animal vaccine producer, welcomes this week's
European decision to allow specific French and Dutch poultry vaccination.
The company also believes that the UK should follow suit and vaccinate
the country's nine million free range hens and other outdoor birds to
help in the fight to keep avian flu out of Britain's avian flocks. This
precautionary measure would prevent the terrible scenes that followed
the foot & mouth outbreak when over four million animals were destroyed.
"The UK has an excellent standard of animal welfare within the poultry
industry but we believe that bringing free range flocks indoors or leaving
them unvaccinated will compromise the welfare of the birds, as well as
risking the spread of disease. In addition, vaccinating all free range
hens is much more cost effective than the compensation that would follow
if the flocks were slaughtered," says Jim Hungerford, General Manager
of Intervet UK Ltd.
Nobilis Influenza has been successfully used in avian flu control programmes
across the globe. The vaccine is scientifically proven to prevent virus
transmission from bird to bird and protects poultry from the clinical
effects of the disease. It also massively reduces - by more than 100,000
fold - the amount of virus in exposed poultry, dramatically diminishing
the risk of spread to humans and the risk of spread to other poultry.
Intervet has been working with many governments, including the UK government,
to advise on outbreak control and management as well as vaccination strategies
aimed at helping bring the epidemic to a halt. One such recommendation
is for governments to commission a 'vaccine bank', whereby they can pre-order
vaccine which is then held in stock and can be delivered within three
days' notice. France and Japan have already established vaccine banks.
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