Frequently asked questions with regard to the Avian flu, answered by Intervet International, March 1, 2006

1 March 2006

Update of FAQ of 22-02-2006

Statement to decision taken by the European Commission:

Intervet welcomes the decision of the European Commission of February 22, 2006, to approve the vaccination plans against bird flu of the French and Dutch Governments. Intervet supports this decision. Preventive vaccination of free range poultry, where the risk of contact with wild birds is the highest, can help to control this risk. If embedded in an overall control program, vaccination contributes substantially to controlling bird flu and reducing the circulation of the virus. 
 
1. Why do you have a vaccine for this strain (H5N1) of avian flu? 

Intervet produces H5 vaccines, which are closely enough related to the present H5N1 strain to induce protection. 

2. How long does it take until animals are protected after vaccination? 

Birds have to build up immunity following vaccination. We have indications that the protection starts already 1-2 weeks after vaccination. After 3 weeks you have a measurable 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. 

3. Information on application 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). If you vaccinate with H5N2 you get a different set of antibodies in the vaccinated animals than in the birds infected with H5N1. You can monitor these antibodies with a test.

In principal there are three test methods available:
- On small scale for selective screening a test based on the DIVA principle can be employed. DIVA stands for Differentiating Infected from Vaccinated Animals. It is a serological test which is based on the fact that a different strain is used to vaccinate (H5N2) than the current field strain (H5N1). This test has been used extensively by Italian authorities in the past. 
-  A possible alternative or addition to check whether the virus is circulating at a farm is to leave a number of un-vaccinated birds in the flock (sentinel birds). These birds have to be clearly identified for monitoring purposes. This principle has been successfully used for example in the eradication campaign in Italy and Hong Kong. In addition, this method was employed during re-stocking of Dutch poultry farms after the outbreak in 2003.
-  For large scale monitoring a so-called RT-PCR (reverse transcription-polymerase chain reaction) can be used. It is based on the detection of parts of the genome of the virus. This method has been used for large scale screening in vaccinating countries (Italy and Hong Kong) and in non-vaccinating countries (a.o. the Netherlands).

5. Does the vaccination mask a field infection?

Vaccinated chickens may still become infected. A minority of these chickens may still excrete a limited amount of virus; however the amount of virus is too small to infect other birds. Criticism on efficacy of vaccine is focused on minor excretion and does not take into account that the excretion does not lead to the transmission of the virus. 
In Hong Kong Intervet vaccine has been used extensively on infected farms. On these farms virus transmission was blocked completely as from 18 days after vaccination. Vaccinated birds no longer transmitted the virus and did not turn into carriers (extensive testing on this had been done).
Further information is available on our dedicated website http://www.avian-influenza.com/

6. Who else makes vaccines against avian flu? 

There are other commercial producers, but also governmental or other institutions are producing and working on vaccines. International commercial producers of avian influenza vaccines are Intervet, Merial and Fort Dodge (Wyeth).

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

Infected birds excrete high amounts of virus in faeces, which facilitates further spread. Bird to bird infection mainly occurs by inhaling virus while 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. 

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

 Statement Intervet
To keep birds healthy, they are vaccinated routinely against various diseases. Poultry products from those vaccinated birds are SAFE for consumption. This is also applicable for birds vaccinated with Intervet’s vaccine Nobilis Influenza. The withdrawal period for the vaccine is zero days. (The withdrawal time is the time which passes between the last dose of a medicine given to the animal and the time when it can be slaughtered and its products can be consumed.)
 
 Statement independent third party
The Netherlands Nutrition Center (Voedingscentrum) points out 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 which 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. 

9. Do you make vaccines for avian flu regularly? 

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

10. 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 in that case. This depends on in which stage of the production process we are if the orders are placed and our stock situation. We can only supply if we receive official orders. We can not guarantee immediate supply if demand is growing.

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

In routine situations it takes months if you start from the suitable antigen in stock before you have produced a batch and have run all required quality control tests. Even if you speed up production if necessary, it still takes several weeks.

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

12. Where is your avian flu vaccine made? 

Intervet routinely produces AI vaccines in Mexico and Spain.

13. How are the birds actually vaccinated? 

Birds are vaccinated by injection (subcutaneously or intramuscularly) with an inactivated vaccine (based on H5N2).

14. What does it cost to make a dose?

Cost per dose is a couple of Euro cents. If you look to the costs of a vaccination campaign the price for the vaccine is one of the smallest amounts. A campaign has its price and is labor intensive. 

15. 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.

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 vaccine Nobilis Influenza 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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