My two year old brahma flock have not been vaccinated for anything. They were on medicated starter as chicks. When my new babies arrive this week I intend to try a cautionary introduction between one of my two year old hens and the chicks. Yes, I know the dangers! but I will be watching the whole time and I feel that it's worth the risk. This hen "Lilith" has always been a loner, never accepted into my flock and I want to see if she can make a new start as part of the second flock. Both she and the new chicks could benefit. She's a very gentle and quiet soul. Then I got to worrying. Never have I had an illness in the flock *knock on wood* but what if there was something? What if there was an illness that was so slight I never saw signs and symptoms, but caused my adult birds to become carriers? Lilith has had an illness herself, but it was from swallowing broken glass. The chicks are going to be with the adult birds at about 3 weeks anyhow. I'll be moving them to the coop in a seperate space. Am I worrying for nothing? I really want to try this with Lilith.