Back to

-----Original Message-----

From: xxxxx (VEROD)

Sent: xxxx

To: xxxxx

Subject: Avian Influenza


Dear xxxx

Provision of requested information

Thank you for your request for information about Avian Influenza which we received on 24 March 2006. Your request has been considered under the Freedom of Information Act 2000.

Information requested for disclosure:

(a) Please would you supply a list of the references which led the Minister and his officials to assert that "It has been a frequently recognised feature of the use of vaccine in the field that vaccinated birds can continue to allow spread of the virus, whilst not showing typical clinical signs."

The following are key references regarding the above. This is not an exhaustive list. This is because the process of establishing this feature has involved many sources available to Defra. Some examples of this would be;

* conference and international meeting presentations

* submissions by the vaccine companies themselves

* international collaborative efforts

* known challenge studies

* the EU avian influenza reference laboratory

* the Veterinary Medicines Directorate

* discussions at EU and international level

* lessons learned by countries that have used vaccination

as a control measure

* summaries undertaken by the FAO and EFSA (references available)

* commercially confidential unpublished material

* internal company reports

* internet and website sources

* review by the Defra Scientific Advisory Committee and

other government scientists


Note : vaccine manufacturers make no claim that their vaccines would completely stop excretion of the virus on a challenge, only that that shedding from vaccinates is reduced.


Capua, I., Terregino, C., Cattoli,G., Toffan,A. (2004b). Increased resistance of vaccinated turkeys to experimental infection with an H7N3 low-pathogenicity avian influenza virus.Avian Pathol. 33(2),158-163.


Swayne D.E . (2003). Vaccines for list A poultry diseases; emphasis on avian influenza. Dev. Biol. ( Basel ), 114 , 201-212.


Swayne D.E. & Suarez D.L. (2000). Highly pathogenic avian influenza. Rev. sci. tech. Off. Int. Epiz ., 19 , 463-482.

van der Goot, J.A., Koch, G., de Jong M.C.M. & van Boven M. (2005) Quantification of the effect of transmission of avian influenza (H7N7) in chickens. Proc. Nat. Acad. Sci. 102, 18141-18146.


Ellis, T.M., Leung, C.Y.H.C., Chow, M.K.W., Bissett, L.A., Wong, W., Guan,Y. & Peiris, J.S.M. (2004). Vaccination of chickens against H5N1 avian influenza in the face of an outbreak interrupts virus transmission  Avian  pathology 33, 405-412.

liu, M., Wood, J.M., Ellis, T., Krauss, S., Seiler, P. et al., (2003). Preparation of a standardized, efficacious, agricultural H5N3 vaccine by reverse genetics. Virology 314, 580-590.

Swayne, D.E., Lee, C-W., & Spackman, E. (2006). Inactivated North American and European H5N2 avian influenza virus vaccines protect chickens from Asian H5N1 high pathogenicity avian influenza virus. Avian Pathology in press.

The people undertaking the work are listed in the references. Scientific journals maintain an anonymous peer review system.

Some of these publications refer to field work, but specifically the following is of significance:

Vaccination against HPNAI of H5N2 subtype was used in Mexico following outbreaks in 1994-1995, and against H7N3 subtype in Pakistan (Garcia et al 1998; Lee et al 2004, Naeem, 1998) following outbreaks in 1995. In Mexico, the HPNAI virus appears to have been eradicated, but LPNAI virus of H5N2 has continued to circulate, despite the use of over 3 billion doses of virus in the last 10 years. In Pakistan highly pathogenic AI viruses genetically close to the original highly pathogenic AI virus were still being isolated in 2004 (Naeem & Siddique 2006).

Garcia A., Johnson H., Kumar Srivastava D., Jayawardene D.A., Wehr D.R. & Webster R.G. (1998). Efficacy of inactivated H5N2 influenza vaccines against lethal A/chicken/Queretaro/19/95 infection. Avian Dis., 42, 248-256.

Naeem K. (1998). The avian influenza H7N3 outbreak in South Central Asia. Proceedings of the Fourth International Symposium on Avian Influenza, Athens, Georgia, USA. Swayne D.E. & Slemons R.D., eds. U.S. Animal Health Association, 31-35.

Lee, C.W., Senne, D.A., Suarez, D.L., (2004). Effect of vaccine use in  the evolution of Mexican lineage H5N2 avian influenza virus. J.Virol. 78(15), 8372-8381.

Naeem, K. and N. Siddique. Use of strategic vaccination for the control of avian influenza in Pakistan. Proceedings of the OIE/FAO International Conference on Avian Influenza. Schudel A., Lombard M. (eds) Developments in Biology vol 124 Basel Karger pp 145-150. 2006.

(b) Who undertook the research to support the publication of the material supporting this statement, and who conducted the peer reviews on this research prior to publication of the material?

The researchers and their affiliations are indicated on the papers referenced. Journals do not generally make the names of their referees public and this information can only be obtained from the publishers.

The information supplied to you continues to be protected by the Copyright, Designs and Patents Act 1988. You are free to use it for your own purposes, including any non-commercial research you are doing and for the purposes of news reporting. Any other re-use, for example commercial publication, would require the permission of the copyright holder.

Most documents supplied by Defra will have been produced by government officials and will be Crown Copyright. You can find details on the arrangements for re-using Crown copyright on OPSI (Office of Public Sector Information) at:

Information you receive which is not subject to Crown Copyright continues to be protected by the copyright of the person, or organisation, from which the information originated. You must ensure that you gain their permission before reproducing any third party (non Crown Copyright) information.  In keeping with the spirit and effect of the Freedom of Information Act 2000/Environmental Information Regulations 2004, all information is assumed to be releasable to the public unless exempt. The information you requested may now be published on our website together with any related information that will provide a key to its wider context.

If you have any queries about this letter, please contact me. I also attach an annexe giving contact details should you be unhappy with the services you have received.