|a11=Vaccination of pullets several weeks before they come into lay. Vaccination protects the flock from a reduction in egg production and prevents vertical transmission of the virus to chicks by providing the chicks with a sufficient level of maternal derived antibodies. There are live and attenuated vaccinations available which can be administered in drinking water or as an eye drop, the latter being more effective. | |a11=Vaccination of pullets several weeks before they come into lay. Vaccination protects the flock from a reduction in egg production and prevents vertical transmission of the virus to chicks by providing the chicks with a sufficient level of maternal derived antibodies. There are live and attenuated vaccinations available which can be administered in drinking water or as an eye drop, the latter being more effective. |