How big is your incubation? Marek's only goes for 1000 doses and above?
If it is a small incubator it is likely not necessary but once you grow close to 1000 egg capacity you will need to get the vaccination, handle it properly, and administer in the right way. At first it is advised for a vet to show you to learn the basics and then do yourself from then onwards.
Any toughts
@nedward ?