Psittimune® APV is recommended for the vaccination of healthy psittacine birds to aid in the prevention of avian polyomavirus infection prior to virus exposure. Young birds are the birds most at risk for this usually fatal disease and should be initially vaccinated at 5 weeks (35 days) of age. To complete primary immunization a second dose must be given at two to three weeks following the initial vaccination. Annual revaccination is recommended. Susceptible breeders should be vaccinated prior to the laying season.