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EU safety agency gives nod to bird flu vaccination

Vaccination programs of poultry with approved drugs and procedures could be used to prevent outbreaks of avian influenza, the EU’s food safety assessment agency said yesterday.

Vaccination programs of poultry with approved drugs and procedures could be used to prevent outbreaks of avian influenza, the EU’s food safety assessment agency said yesterday. Mass vaccination is seen as one way of calming consumers’ fears about the safety of the bloc’s poultry flock. Consumption of poultry and poultry products plunged by as much as 70% in some countries at the start of last year due to outbreaks in member states.

However scientists and regulators differ about mass vaccination, as some fear that its use in domestic poultry may hinder detection of the deadly H5N1 strain of the disease. The scientific opinion by the European Food Safety Agency (EFSA) could help resolve the differences of opinion among the bloc’s member states about whether to allow poultry processors to vaccinate their flocks. “The use of EU authorized vaccines per se is recommended because is safe and has no negative effect on poultry products for consumers,” EFSA stated.

The EU authorized vaccines for poultry such as chickens and ducks meet the relevant quality standards. However more study is needed before an opinion could be made about the use of vaccination for other poultry, EFSA stated. According to the EFSA monitoring strategies combined with the use of sentinel birds in order to detect possible transmission after vaccination, must be employed to allow the detection of a possibly circulating field strain.

Last year the European Centre for Disease Prevention and Control warned that vaccination programs that are widely but imperfectly instituted in poultry, like those in China and Indonesia, may impede detection of human cases. Mass vaccination can also serve to disguise the presence of any H5N1 that manages to survive in inoculated flocks, and thus pose a great danger, others have argued. So far the European Commission and member countries have resisted calls for mass vaccination of the domestic poultry stock.

Limited vaccinations have been done in areas where bird flu outbreaks have occurred. While no human case of the H5N1 virus has occurred in the EU, scientists worldwide have been worried that H5N1, which can pass from poultry to humans, may mutate so that it can be transmitted from human to human and start a influenza pandemic. At least three countries - China, Indonesia and Viet Nam - are undertaking large-scale poultry vaccination programs against H5N1, alongside with the mass culling of millions of birds.

“If poultry immunization is efficient and well monitored it could reduce the population burden of H5N1 in poultry and hence the risk for humans,” the CDPC stated. “Equally however if it leads to the silent circulation of H5N1 in poultry it could actually increase the threat to humans in those countries and the risk of co-infection with other influenzas… Falling numbers of reported human cases in countries practicing large scale poultry immunization may therefore be misleading.” Outbreaks of highly pathogenic avian influenza (HPAI) viruses in domestic poultry have been increasing since the late 1990s and have affected poultry in Europe as elsewhere.

The continuing fight against the spread of avian influenza throughout Europe has focused on preventing the spread of the disease to domestic flocks from wild birds. Previous outbreaks have occurred in domestic poultry in France, Sweden, Germany and Denmark. Cases of avian influenza H5N1 have occurred in wild birds in thirteen member states of the EU to date - Greece, Italy, Slovenia, Hungary, Austria, Germany, France, Slovakia, Sweden, Poland, Denmark, Czech Republic and more recently, the UK. In March last year the European Commission approved limited vaccination of bird flocks in certain areas of the Netherlands and France.

Vaccination ended 1 April 2006. Sentinel birds, which are unvaccinated control birds, were used as part of the monitoring for avian influenza. The Commission and member states also backed allowing Germany to go ahead with field research into a vaccination program. The German authorities are carrying out on three commercial farms in North Rhine Westphalia over the two-year trial period. The vaccination will be carried out for research purposes only, as part of a major field study to determine the effects and results of vaccinating against avian influenza, the Commission stated. None of the poultry used in the research, nor their meat and eggs, will be put on the market. (