I bought 6 vaccinated chicks from a hatchery in March. I bought an UNvaccinated chick to add to the frock a couple days later. A couple months later, I bought an UNvaccinated pullet. One of my vaccinated chicks started showing signs of Marek's in June. We didn't think it was Marek's bc she had been vaccinated. We actually took her to the avian vet a few times and since she wasn't getting better, we recently had her put down. The vet did a free necropsy and confirmed Marek's. Either the hatchery missed her when vaccinating, or she's one of the unlucky 5% that still get infected after being vaccinated. Or maybe the vaccine only covers certain strains of Marek's?? Anyway, now it's safe to say my other 7 birds are carriers, although they haven't shown any signs...yet. Now, my question is: If I add a vaccinated bird to my flock, will she be safe since she is vaccinated even though my other birds are carriers? That's what a vaccine is for, right?