My first two chickens died of mareks disease. After the first one died we got a friend for her who we still have (who was mareks vaccinated). It was only when the second of the original chickens died that we knew we were definately dealing with marek's disease. I bought two more mareks vaccinated birds to keep the remaining one company. Some months on all seems fine but the other day I read that the marek's vaccine doesn't stop them getting mareks it only stops the tumours developing,is this true? Are my vaccinated hens in danger of becoming sick as a result of the mareks they have undoubtedly been exposed to?