title: Evaluation of the vaccination efficacy against H5N1 in domestic poultry in the Red River Delta in Vietnam.
abstract: The domestic poultry population in Vietnam has been vaccinated against highly pathogenic avian influenza (HPAI) H5N1 since 2005. Since then, outbreaks have continued to occur without a clear understanding of the mechanisms involved. The general objective of this study was to understand the epidemiology of the disease in the context of vaccination and to draw some conclusions about vaccination efficacy in the domestic poultry population of the Red River Delta area. Five cross-sectional surveys to measure the serological and virological prevalence in vaccinated and unvaccinated poultry were performed from the end of 2008 to June 2010. The global seroprevalence was 24% (95% confidence interval 19·9-28·2). Determinants of vaccine immunogenicity were identified separately in chickens and ducks as well as determinants of the seroconversion in unvaccinated birds. The results highlight the difficulties in maintaining good flock immunity in poultry populations using inactivated vaccine in the field with two vaccination rounds per year, and in preventing circulation of virus in co-existing unvaccinated poultry.
authors: Direction Régionale de l'Alimentation, de l'Agriculture et de la Forêt de Languedoc-Roussillon (DRAAF-LR), Maison de l'Agriculture, place Antoine Chaptal, Montpellier Cedex 02, France. stephanie.desvaux@agriculture.gouv.fr
authors: S
authors: S
authors: Desvaux
authors: V
authors: V
authors: Grosbois
authors: T T H
authors: TT
authors: Pham
authors: D T
authors: DT
authors: Dao
authors: T D
authors: TD
authors: Nguyen
authors: S
authors: S
authors: Fenwick
authors: F
authors: F
authors: Roger
authors: T
authors: T
authors: Ellis
authors: M
authors: M
authors: Peyre
mesh_terms: D000818:Animals; D002645:Chickens / Q000821:virology*; D003430:Cross-Sectional Studies; D004196:Disease Outbreaks / Q000662:veterinary; D004372:Ducks / Q000821:virology*; D005777:Geese / Q000821:virology*; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000097:blood; D053124:Influenza A Virus, H5N1 Subtype / Q000276:immunology* / Q000302:isolation & purification; D007252:Influenza Vaccines / Q000627:therapeutic use*; D005585:Influenza in Birds / Q000453:epidemiology / Q000517:prevention & control*; D016133:Polymerase Chain Reaction; D016036:Seroepidemiologic Studies; D014611:Vaccination / Q000662:veterinary; D014744:Vietnam / Q000453:epidemiology
chemical_list: D019267:Hemagglutinin Glycoproteins, Influenza Virus; D007252:Influenza Vaccines