A method for preparing a vaccine composition to be implemented in a locally administered treatment for avian viral disease, includes at least the step of: a) extemporaneously mixing a vaccine, including at least one live virus selected from a virus belonging to one or more strains of the avian disease, with an adjuvant diluent (DA), characterized in that the adjuvant diluent is a continuous aqueous phase oil-in-water emulsion or oil-in-water microemulsion.
