Challenges and issues of early life vaccination in animals and humans.

This overview considers the major issues related to successful neonatal vaccination of domestic animals. A major factor is the balance between the essential protection provided by maternally derived immunity and the potential inhibitory effects of this immunity on generation of the neonatal vaccinal immune response. The design of vaccine programs should also take into account the predicted life expectancy and husbandry of the animal species concerned. Relatively short-lived production animals or wildlife species may have different vaccination requirements from long-lived companion animals. The purpose of vaccination also differs depending upon the animals concerned, and may range from the establishment of protective immunity in the individual animal or herd, through to programs designed to eliminate an infectious agent from a specific geographical area.