Should lambing extend over a period of more than six weeks, the duration of transferred colostral protection in the later-born lambs may be shortened. These lambs should be given their first dose of Covexin 8 from eight weeks of age.
In any animal population there may be a small number of individuals which fail to respond fully to vaccination. Successful vaccination depends upon correct storage and administration of the vaccine together with the animal's ability to respond. This can be influenced by such factors as genetic constitution, intercurrent infection, age, the presence of maternally-derived antibodies, nutritional status, concurrent drug therapy and stress.