This year I was planning on taking my chickens to the fair, but I have heard there has been a Marek's scare around my area. I know when taking your animals to fair you are taking your chances when it comes to getting diseases, but I wanted to know, can I vaccinate my adult birds against this disease just to be safe? Or does it not work with older chickens? None of our chickens have ever received the vaccination that we know of. We have purchased a few from feed stores and from private breeders but have never even thought about asking if they have vaccinated them.