Vaccination timing

Vaccination with live IBDV vaccines

Live vaccines are administered to achieve active immunity. Interference of MDA is the crucial problem in determining a successful live IBDV vaccination schedule.

  • Vaccinating in the presence of high levels of MDA results in vaccine virus neutralisation and no immunity.
  • Waiting until an age when MDA levels have declined to very low levels could result in a pathogenic field virus challenge before vaccination. (See this figure).
  • To assist in determining the optimal vaccination age a formula (Deventer Calculator) based on the MDA titre of young chicks has been developed.
chicken

Interference of MDA is the crucial problem in determining a successful live IBDV vaccination schedule.