Single vaccination provides limited protection to ducks and geese against H5N1 high pathogenicity avian influenza virus

Since 2002, high pathogenicity avian influenza (HPAI) has spread from Asia to Europe and into Africa, causing the largest epizootic of HPAI of the last 50 yr, including infecting domestic and wild waterfowl. Our study was conducted to investigate whether a single vaccination of 7-day-old domestic ducks and geese with inactivated oil emulsion vaccines resulted in protection against HPAI virus challenge at 30 days of age. In ducks, some but not all vaccines decreased oropharyngeal and cloacal viral shedding for different periods postchallenge when compared with the sham group. In geese, decreased morbidity signs and mortality were noted but limited to some vaccines. Best protection was seen with a vaccine homologous to HPAI challenge virus. Limited decreases in oropharyngeal and cloacal viral shedding and mixed results were attained when looking at seroconversion. Our results indicate a single dose of oil-emulsified vaccine optimized for chickens did not provide adequate protection for ducks and geese against HPAI virus, and, at a minimum, additional research is needed to formulate waterfowl-specific vaccines.