LPM 221: Commercial Poultry Production and Hatchery Management (1+1)

REASONS FOR VACCINATION FAILURE

• The recipient is already infected with the virus or is sick or has an immunosuppressive infection.
• Antigenic differences between the vaccine and challenge virus eg influenza.
• Increase in virulence of the challenge virus.
• Break down of the cold-chain during transport e.g. tissue-culture vaccines.
• Improper administration- disinfectant in the syringe.
• The vaccine has been overgrown by an irrelevant virus/bacterium, no antigen-potency testing done