Vaccination parameter validation can be ambiguous when a herd is initially naturally immmune

Component:User interface
Category:feature request
Priority:as time allows
The validation check of vaccination parameters normally will catch when vaccination is on for a production type but production type vaccination ring targets or triggers are not specified. However, if any units are initially vaccine immune then this circumstance is ignored because the modeler could be examing a scenario where a proportion of the population was vaccinated but no further vaccination will occur. It would be nice to have a warning message for this situation, though it is a valid circumstance it may not be what the modeler intended to model.