I usually get mine vaccinated before I get them.....but lost one to a form of Mareks AFTER it was vaccinated and had absolutely no problem with the ones I've gotten that were not vaccinated. From what I read, if you hatch them yourself and raise them yourself you are probably ok....it's when you introduce others to yours that you risk infection. The one that was infected was not raised by me.....I was lucky that she had a form of Mareks that was not easily spread and I caught it early so the rest of mine were ok. It was just strange, she showed no typical symptoms and was 9 months old which is usually too old to get it. .....it's a crap shoot.I don't.